Programs & Examples On #Vertica

Vertica is a column-based database that runs on clusters of Linux servers. The Vertica Analytics Platform was part of HP Software's Big Data Platform called HP Haven and moved to Micro Focus. It is also available as a SaaS based solution called Vertica OnDemand. See the "hp-haven" tag for more related questions.

Highlight Anchor Links when user manually scrolls?

You can use Jquery's on method and listen for the scroll event.

strange error in my Animation Drawable

Looks like whatever is in your Animation Drawable definition is too much memory to decode and sequence. The idea is that it loads up all the items and make them in an array and swaps them in and out of the scene according to the timing specified for each frame.

If this all can't fit into memory, it's probably better to either do this on your own with some sort of handler or better yet just encode a movie with the specified frames at the corresponding images and play the animation through a video codec.

Uncaught Invariant Violation: Too many re-renders. React limits the number of renders to prevent an infinite loop

I also have the same problem, and the solution is I didn't bind the event in my onClick. so when it renders for the first time and the data is more, which ends up calling the state setter again, which triggers React to call your function again and so on.

export default function Component(props) {

function clickEvent (event, variable){

return (
            onClick={e => clickEvent(e, 10)} // or you can call like this:onClick={() => clickEvent(10)} 

Flutter: RenderBox was not laid out

You can add some code like this

   shrinkWrap: true,

Center content vertically on Vuetify

For me, align="center" was enough to center FOO vertically:

<v-row align="center">

Flutter - The method was called on null

You should declare your method first in void initState(), so when the first time pages has been loaded, it will init your method first, hope it can help

Flutter : Vertically center column

You control how a row or column aligns its children using the mainAxisAlignment and crossAxisAlignment properties. For a row, the main axis runs horizontally and the cross axis runs vertically. For a column, the main axis runs vertically and the cross axis runs horizontally.


Flutter: Setting the height of the AppBar

You can use PreferredSize:

class MyApp extends StatelessWidget {
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Example',
      home: Scaffold(
        appBar: PreferredSize(
          preferredSize: Size.fromHeight(50.0), // here the desired height
          child: AppBar(
            // ...
        body: // ...

How do I center text vertically and horizontally in Flutter?

maybe u want to provide the same width and height for 2 container

            width: size.width * 0.30, height: size.height * 0.4,
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(6)
            child: Center(
              child: Text(categoryName, textAlign:, style: TextStyle(
                fontWeight: FontWeight.bold,
                fontSize: 17,
                color: Colors.white,

Failed linking file resources

If anyone reading this has the same problem, this happened to me recently, and it was due to having the xml header written twice by mistake:

<?xml version="1.0" encoding="utf-8"?>
<?xml version="1.0" encoding="utf-8"?> <!-- Remove this one -->
<shape xmlns:android="">
     <solid android:color="@color/mug_blue"/>
     <corners android:radius="@dimen/featured_radius" />

The error I was getting was completely unrelated to this file so it was a tough one to find. Just make sure all your new xml files don't have some kind of mistake like this (as it doesn't show up as an error). EDIT It seems like it shows up as an error now, make sure to check your error logs.

How to Set/Update State of StatefulWidget from other StatefulWidget in Flutter?

I would like to extend Mohamed Elrashid answer, in case you require to pass a variable from the child widget to the parent widget

On child widget:

class ChildWidget extends StatefulWidget {
  final Function() notifyParent;
  ChildWidget({Key key, @required this.notifyParent}) : super(key: key);

On parent widget

void refresh(dynamic childValue) {
  setState(() {
    _parentVariable = childValue;

On parent widget: pass the function above to the child widget

new ChildWidget( notifyParent: refresh ); 

On child widget: call the parent function with any variable from the the child widget


No provider for HttpClient

Add HttpModule and HttpClientModule in both imports and providers in app.module.ts solved the issue. imports -> import {HttpModule} from "@angular/http"; import {HttpClientModule} from "@angular/common/http";

How to create a stacked bar chart for my DataFrame using seaborn?

You could use pandas plot as @Bharath suggest:

import seaborn as sns
df.set_index('App').T.plot(kind='bar', stacked=True)


enter image description here


from matplotlib.colors import ListedColormap df.set_index('App')\ .reindex_axis(df.set_index('App').sum().sort_values().index, axis=1)\ .T.plot(kind='bar', stacked=True, colormap=ListedColormap(sns.color_palette("GnBu", 10)), figsize=(12,6))

Updated Pandas 0.21.0+ reindex_axis is deprecated, use reindex

from matplotlib.colors import ListedColormap

  .reindex(df.set_index('App').sum().sort_values().index, axis=1)\
  .T.plot(kind='bar', stacked=True,
          colormap=ListedColormap(sns.color_palette("GnBu", 10)), 


enter image description here

Bootstrap 4 - Inline List?


Remove a list’s bullets and apply some light margin with a combination of two classes, .list-inline and .list-inline-item.

<ul class="list-inline">
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">FB</a></li>
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">G+</a></li>
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">T</a></li>

Constraint Layout Vertical Align Center


Flutter - Wrap text on overflow, like insert ellipsis or fade

One way to fix an overflow of a Text Widget within a row if for example a chat message can be one really long line. You can create a Container and a BoxConstraint with a maxWidth in it.

              constraints: BoxConstraints(maxWidth: 200),
                child: Text(
                  (chatName == null) ? " ": chatName,
                  style: TextStyle(
                      fontWeight: FontWeight.w400,
                      color: Colors.black87,
                      fontSize: 17.0),

Failed to load AppCompat ActionBar with unknown error in android studio

June 2018 Issue fixed by using a different appcompact version. Use these codes onto your project dependencies...

In build.gradle(Module: app) add this dependency

implementation ''

Happy Coding... :)

Error: the entity type requires a primary key

Removed and added back in the table using Scaffold-DbContext and the error went away

Bootstrap 4 Center Vertical and Horizontal Alignment

This is working in IE 11 with Bootstrap 4.3. While the other answers were not working in IE11 in my case.

 <div class="row mx-auto justify-content-center align-items-center flex-column ">
    <div class="col-6">Something </div>

Vertical Align Center in Bootstrap 4

<div class="row">
  <div class="col-md-6">
     <img src="/assets/images/ebook2.png" alt="" class="img-fluid">
  <div class="col-md-6 my-auto">
     <p>Some text.</p>

This line is where the magic happens <div class="col-md-6 my-auto">, the my-auto will center the content of the column. This works great with situations like the code sample above where you might have a variable sized image and need to have the text in the column to the right line up with it.

VSCode: How to Split Editor Vertically

By default, editor groups are laid out in vertical columns (e.g. when you split an editor to open it to the side). You can easily arrange editor groups in any layout you like, both vertically and horizontally:

To support flexible layouts, you can create empty editor groups. By default, closing the last editor of an editor group will also close the group itself, but you can change this behavior with the new setting workbench.editor.closeEmptyGroups: false:

enter image description here

There are a predefined set of editor layouts in the new View > Editor Layout menu:

enter image description here

Editors that open to the side (for example by clicking the editor toolbar Split Editor action) will by default open to the right hand side of the active editor. If you prefer to open editors below the active one, configure the new setting workbench.editor.openSideBySideDirection: down.

There are many keyboard commands for adjusting the editor layout with the keyboard alone, but if you prefer to use the mouse, drag and drop is a fast way to split the editor into any direction:

enter image description here

Keyboard shortcuts# Here are some handy keyboard shortcuts to quickly navigate between editors and editor groups.

If you'd like to modify the default keyboard shortcuts, see Key Bindings for details.

??? go to the right editor.
??? go to the left editor.
^Tab open the next editor in the editor group MRU list.
^?Tab open the previous editor in the editor group MRU list.
?1 go to the leftmost editor group.
?2 go to the center editor group.
?3 go to the rightmost editor group.
unassigned go to the previous editor group.
unassigned go to the next editor group.
?W close the active editor.
?K W close all editors in the editor group.
?K ?W close all editors.

Simple Android RecyclerView example

This will be the simplest version of the implementation of RecyclerView.

enter image description here


<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android=""




<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""

        android:textSize="16dp" />


public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
  private List<String> data;
  public CustomAdapter (List<String> data){ = data;

  public CustomAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View rowItem = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_view, parent, false);
    return new ViewHolder(rowItem);

  public void onBindViewHolder(CustomAdapter.ViewHolder holder, int position) {

  public int getItemCount() {

  public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    private TextView textView;

    public ViewHolder(View view) {
      this.textView = view.findViewById(;

    public void onClick(View view) {
      Toast.makeText(view.getContext(), "position : " + getLayoutPosition() + " text : " + this.textView.getText(), Toast.LENGTH_SHORT).show();

public class MainActivity extends AppCompatActivity {

  protected void onCreate(Bundle savedInstanceState) {

    RecyclerView recyclerView = findViewById(;
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setAdapter(new CustomAdapter(generateData()));
    recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));

  private List<String> generateData() {
    List<String> data = new ArrayList<>();
    for (int i = 0; i < 100; i++) {
      data.add(String.valueOf(i) + "th Element");
    return data;


Sublime text 3. How to edit multiple lines?

Thank you for all answers! I found it! It calls "Column selection (for Sublime)" and "Column Mode Editing (for Notepad++)"

how to set start value as "0" in chartjs?

Please add this option:

//Boolean - Whether the scale should start at zero, or an order of magnitude down from the lowest value
scaleBeginAtZero : true,

(Reference: Chart.js)

N.B: The original solution I posted was for Highcharts, if you are not using Highcharts then please remove the tag to avoid confusion

This view is not constrained vertically. At runtime it will jump to the left unless you add a vertical constraint

Constraint layout aims at reducing layout hierarchies and improves performance of layouts(technically, you don't have to make changes for different screen sizes,No overlapping, works like charm on a mobile as well as a tab with the same constraints).Here's how you get rid of the above error when you're using the new layout editor.

enter image description here

Click on the small circle and drag it to the left until the circle turns green,to add a left constraint(give a number, say x dp. Repeat it with the other sides and leave the bottom constraint blank if you have another view below it. enter image description here

Edit: According to the developers site, Instead of adding constraints to every view as you place them in the layout, you can move each view into the positions you desire, and then click Infer Constraints to automatically create constraints. more here

ReactNative: how to center text?

The following property can be used: {{alignItems: 'center'}}

<View style={{alignItems: 'center'}}>
 <Text> Hello i'm centered text</Text>

Change Spinner dropdown icon

I have had a lot of difficulty with this as I have a custom spinner, if I setBackground then the Drawable would stretch. My solution to this was to add a drawable to the right of the Spinner TextView. Heres a code snippet from my Custom Spinner. The trick is to Override getView and customize the Textview as you wish.

public class NoTextSpinnerArrayAdapter extends ArrayAdapter<String> {

    private String text = "0";

    public NoTextSpinnerArrayAdapter(Context context, int textViewResourceId, List<String> objects) {
        super(context, textViewResourceId, objects);

    public void updateText(String text){
        this.text = text;

    public String getText(){
        return text;

    public View getView(int position, View convertView, @NonNull ViewGroup parent) {
        View view = super.getView(position, convertView, parent);
        TextView textView = view.findViewById(;
        textView.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_menu_white_24dp, 0);

        return view;

You also need to set the Spinner background to transparent:

            tools:layout_editor_absoluteY="16dp" />

and my custom spinner if you want it....

public class SelectAgainSpinner extends {
    public SelectAgainSpinner(Context context) {

    public SelectAgainSpinner(Context context, AttributeSet attrs) {
        super(context, attrs);

    public SelectAgainSpinner(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    public void setPopupBackgroundDrawable(Drawable background) {

    public void setSelection(int position, boolean animate) {
        boolean sameSelected = position == getSelectedItemPosition();
        super.setSelection(position, animate);
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            if (getOnItemSelectedListener() != null) {
                getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());

    public void setSelection(int position) {
        boolean sameSelected = position == getSelectedItemPosition();
        if (sameSelected) {
            // Spinner does not call the OnItemSelectedListener if the same item is selected, so do it manually now
            if (getOnItemSelectedListener() != null) {
                getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());

CSS3 100vh not constant in mobile browser

I came up with a React component – check it out if you use React or browse the source code if you don't, so you can adapt it to your environment.

It sets the fullscreen div's height to window.innerHeight and then updates it on window resizes.

How to draw a line with matplotlib?

I was checking how ax.axvline does work, and I've written a small function that resembles part of its idea:

import matplotlib.pyplot as plt
import matplotlib.lines as mlines

def newline(p1, p2):
    ax = plt.gca()
    xmin, xmax = ax.get_xbound()

    if(p2[0] == p1[0]):
        xmin = xmax = p1[0]
        ymin, ymax = ax.get_ybound()
        ymax = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmax-p1[0])
        ymin = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmin-p1[0])

    l = mlines.Line2D([xmin,xmax], [ymin,ymax])
    return l

So, if you run the following code you will realize how does it work. The line will span the full range of your plot (independently on how big it is), and the creation of the line doesn't rely on any data point within the axis, but only in two fixed points that you need to specify.

import numpy as np
x = np.linspace(0,10)
y = x**2

p1 = [1,20]
p2 = [6,70]

plt.plot(x, y)

enter image description here

How to remove title bar from the android activity?

You can try:

<activity android:name=".YourActivityName"

that works for me

How to add colored border on cardview?

I solved this by putting two CardViews in a RelativeLayout. One with background of the border color and the other one with the image. (or whatever you wish to use)

Note the margin added to top and start for the second CardView. In my case I decided to use a 2dp thick border.


                android:layout_height="36dp" />



            android:layout_height="32dp" />


android: data binding error: cannot find symbol class


Your layout name is in snake_case.


Then your binding class name will be in CamelCase.

Also build project after creating layout. Sometimes it is not generated automatically.

What is the hamburger menu icon called and the three vertical dots icon called?

Cannot say about the "official nomenclature" - infact I wonder whose word will be "official" anyway - but here's how they can be called:

How to add a recyclerView inside another recyclerView

I would like to suggest to use a single RecyclerView and populate your list items dynamically. I've added a github project to describe how this can be done. You might have a look. While the other solutions will work just fine, I would like to suggest, this is a much faster and efficient way of showing multiple lists in a RecyclerView.

The idea is to add logic in your onCreateViewHolder and onBindViewHolder method so that you can inflate proper view for the exact positions in your RecyclerView.

I've added a sample project along with that wiki too. You might clone and check what it does. For convenience, I am posting the adapter that I have used.

public class DynamicListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private static final int FOOTER_VIEW = 1;
    private static final int FIRST_LIST_ITEM_VIEW = 2;
    private static final int FIRST_LIST_HEADER_VIEW = 3;
    private static final int SECOND_LIST_ITEM_VIEW = 4;
    private static final int SECOND_LIST_HEADER_VIEW = 5;

    private ArrayList<ListObject> firstList = new ArrayList<ListObject>();
    private ArrayList<ListObject> secondList = new ArrayList<ListObject>();

    public DynamicListAdapter() {

    public void setFirstList(ArrayList<ListObject> firstList) {
        this.firstList = firstList;

    public void setSecondList(ArrayList<ListObject> secondList) {
        this.secondList = secondList;

    public class ViewHolder extends RecyclerView.ViewHolder {
        // List items of first list
        private TextView mTextDescription1;
        private TextView mListItemTitle1;

        // List items of second list
        private TextView mTextDescription2;
        private TextView mListItemTitle2;

        // Element of footer view
        private TextView footerTextView;

        public ViewHolder(final View itemView) {

            // Get the view of the elements of first list
            mTextDescription1 = (TextView) itemView.findViewById(;
            mListItemTitle1 = (TextView) itemView.findViewById(;

            // Get the view of the elements of second list
            mTextDescription2 = (TextView) itemView.findViewById(;
            mListItemTitle2 = (TextView) itemView.findViewById(;

            // Get the view of the footer elements
            footerTextView = (TextView) itemView.findViewById(;

        public void bindViewSecondList(int pos) {

            if (firstList == null) pos = pos - 1;
            else {
                if (firstList.size() == 0) pos = pos - 1;
                else pos = pos - firstList.size() - 2;

            final String description = secondList.get(pos).getDescription();
            final String title = secondList.get(pos).getTitle();


        public void bindViewFirstList(int pos) {

            // Decrease pos by 1 as there is a header view now.
            pos = pos - 1;

            final String description = firstList.get(pos).getDescription();
            final String title = firstList.get(pos).getTitle();


        public void bindViewFooter(int pos) {
            footerTextView.setText("This is footer");

    public class FooterViewHolder extends ViewHolder {
        public FooterViewHolder(View itemView) {

    private class FirstListHeaderViewHolder extends ViewHolder {
        public FirstListHeaderViewHolder(View itemView) {

    private class FirstListItemViewHolder extends ViewHolder {
        public FirstListItemViewHolder(View itemView) {

    private class SecondListHeaderViewHolder extends ViewHolder {
        public SecondListHeaderViewHolder(View itemView) {

    private class SecondListItemViewHolder extends ViewHolder {
        public SecondListItemViewHolder(View itemView) {

    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View v;

        if (viewType == FOOTER_VIEW) {
            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_footer, parent, false);
            FooterViewHolder vh = new FooterViewHolder(v);
            return vh;

        } else if (viewType == FIRST_LIST_ITEM_VIEW) {
            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_first_list, parent, false);
            FirstListItemViewHolder vh = new FirstListItemViewHolder(v);
            return vh;

        } else if (viewType == FIRST_LIST_HEADER_VIEW) {
            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_first_list_header, parent, false);
            FirstListHeaderViewHolder vh = new FirstListHeaderViewHolder(v);
            return vh;

        } else if (viewType == SECOND_LIST_HEADER_VIEW) {
            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_second_list_header, parent, false);
            SecondListHeaderViewHolder vh = new SecondListHeaderViewHolder(v);
            return vh;

        } else {
            // SECOND_LIST_ITEM_VIEW
            v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_second_list, parent, false);
            SecondListItemViewHolder vh = new SecondListItemViewHolder(v);
            return vh;

    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        try {
            if (holder instanceof SecondListItemViewHolder) {
                SecondListItemViewHolder vh = (SecondListItemViewHolder) holder;

            } else if (holder instanceof FirstListHeaderViewHolder) {
                FirstListHeaderViewHolder vh = (FirstListHeaderViewHolder) holder;

            } else if (holder instanceof FirstListItemViewHolder) {
                FirstListItemViewHolder vh = (FirstListItemViewHolder) holder;

            } else if (holder instanceof SecondListHeaderViewHolder) {
                SecondListHeaderViewHolder vh = (SecondListHeaderViewHolder) holder;

            } else if (holder instanceof FooterViewHolder) {
                FooterViewHolder vh = (FooterViewHolder) holder;
        } catch (Exception e) {

    public int getItemCount() {

        int firstListSize = 0;
        int secondListSize = 0;

        if (secondList == null && firstList == null) return 0;

        if (secondList != null)
            secondListSize = secondList.size();
        if (firstList != null)
            firstListSize = firstList.size();

        if (secondListSize > 0 && firstListSize > 0)
            return 1 + firstListSize + 1 + secondListSize + 1;   // first list header, first list size, second list header , second list size, footer
        else if (secondListSize > 0 && firstListSize == 0)
            return 1 + secondListSize + 1;                       // second list header, second list size, footer
        else if (secondListSize == 0 && firstListSize > 0)
            return 1 + firstListSize;                            // first list header , first list size
        else return 0;

    public int getItemViewType(int position) {

        int firstListSize = 0;
        int secondListSize = 0;

        if (secondList == null && firstList == null)
            return super.getItemViewType(position);

        if (secondList != null)
            secondListSize = secondList.size();
        if (firstList != null)
            firstListSize = firstList.size();

        if (secondListSize > 0 && firstListSize > 0) {
            if (position == 0) return FIRST_LIST_HEADER_VIEW;
            else if (position == firstListSize + 1)
                return SECOND_LIST_HEADER_VIEW;
            else if (position == secondListSize + 1 + firstListSize + 1)
                return FOOTER_VIEW;
            else if (position > firstListSize + 1)
                return SECOND_LIST_ITEM_VIEW;
            else return FIRST_LIST_ITEM_VIEW;

        } else if (secondListSize > 0 && firstListSize == 0) {
            if (position == 0) return SECOND_LIST_HEADER_VIEW;
            else if (position == secondListSize + 1) return FOOTER_VIEW;
            else return SECOND_LIST_ITEM_VIEW;

        } else if (secondListSize == 0 && firstListSize > 0) {
            if (position == 0) return FIRST_LIST_HEADER_VIEW;
            else return FIRST_LIST_ITEM_VIEW;

        return super.getItemViewType(position);

There is another way of keeping your items in a single ArrayList of objects so that you can set an attribute tagging the items to indicate which item is from first list and which one belongs to second list. Then pass that ArrayList into your RecyclerView and then implement the logic inside adapter to populate them dynamically.

Hope that helps.

android : Error converting byte to dex

Thing that worked for me.

  1. Go to android folder of your app.
  2. Run ./gradlew clean

Bootstrap 4 - Responsive cards in card-columns

I have created a Cards Layout - 3 cards in a row using Bootstrap 4 / CSS3 (of course its responsive). The following example uses basic Bootstrap 4 classes such as container, row, col-x, list-group and list-group-item. Thought to share here if someone is interested in this sort of a layout.

enter image description here


<div class="container">
  <div class="row">
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">        
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>


$primary-color: #ccc;
$col-bg-color: #eee;
$col-footer-bg-color: #eee;
$col-header-bg-color: #007bff;
$col-content-bg-color: #fff;

body {
  background-color: $primary-color;

.custom-column {  
  background-color: $col-bg-color;
  border: 5px solid $col-bg-color;    
  padding: 10px;
  box-sizing: border-box;  

.custom-column-header {
  font-size: 24px;
  background-color: #007bff;  
  color: white;
  padding: 15px;  
  text-align: center;

.custom-column-content {
  background-color: $col-content-bg-color;
  border: 2px solid white;  
  padding: 20px;  

.custom-column-footer {
  background-color: $col-footer-bg-color;   
  padding-top: 20px;
  text-align: center;

Link :-

RecyclerView - Get view at particular position

To get a View from a specific position of recyclerView you need to call findViewHolderForAdapterPosition(position) on recyclerView object that will return RecyclerView.ViewHolder

from the returned RecyclerView.ViewHolder object with itemView you can access all Views at that particular position

RecyclerView.ViewHolder rv_view = recyclerView.findViewHolderForAdapterPosition(position);

ImageView iv_wish = rv_view.itemView.findViewById(;

Chrome / Safari not filling 100% height of flex parent

I have had a similar issue in iOS 8, 9 and 10 and the info above couldn't fix it, however I did discover a solution after a day of working on this. Granted it won't work for everyone but in my case my items were stacked in a column and had 0 height when it should have been content height. Switching the css to be row and wrap fixed the issue. This only works if you have a single item and they are stacked but since it took me a day to find this out I thought I should share my fix!

.wrapper {
    flex-direction: column; // <-- Remove this line
    flex-direction: row; // <-- replace it with
    flex-wrap: wrap; // <-- Add wrapping

.item {
    width: 100%;

In android how to set navigation drawer header image and name programmatically in class file?

I know this is an old post but i am sure that this might help someone down the road.

You can simply get the headerView element of the Navigation view by doing this:

 NavigationView mView = ( NavigationView ) findViewById( );

 if( mView != null ){
     LinearLayout mParent = ( LinearLayout ) mView.getHeaderView( 0 );

     if( mParent != null ){
        // Set your values to the image and text view by declaring and setting as you need to here. 

I hope that this helps someone.

Shrink to fit content in flexbox, or flex-basis: content workaround?

I want columns One and Two to shrink/grow to fit rather than being fixed.

Have you tried: flex-basis: auto

or this:

flex: 1 1 auto, which is short for:

  • flex-grow: 1 (grow proportionally)
  • flex-shrink: 1 (shrink proportionally)
  • flex-basis: auto (initial size based on content size)

or this:

main > section:first-child {
    flex: 1 1 auto;
    overflow-y: auto;

main > section:nth-child(2) {
    flex: 1 1 auto;
    overflow-y: auto;

main > section:last-child {
    flex: 20 1 auto;
    display: flex;
    flex-direction: column;  

revised demo


Recyclerview inside ScrollView not scrolling smoothly

<?xml version="1.0" encoding="utf-8"?>
< xmlns:android=""




                    app:layout_constraintRight_toRightOf="parent" />



                    app:layout_constraintRight_toRightOf="parent" />





This code is working for in ConstraintLayout android

In CSS Flexbox, why are there no "justify-items" and "justify-self" properties?

I just found my own solution to this problem, or at least my problem.
I was using justify-content: space-around instead of justify-content: space-between;.

This way the end elements will stick to the top and bottom, and you could have custom margins if you wanted.

Android:java.lang.OutOfMemoryError: Failed to allocate a 23970828 byte allocation with 2097152 free bytes and 2MB until OOM

For me, the problem was that my .png file was being de-compressed to be a really huge bitmap in memory, because the image had very large dimensions (even though the file size was tiny).

So the fix was to simply resize the image :)

Changing text color of menu item in navigation drawer

This may help It worked for me

Go to activity_"navigation activity name".xml Inside NavigationView insert this code

app:itemTextColor="color of your choice"

Does React Native styles support gradients?

Just export your gradient as SVG and use it using react-native-svg and when after you import your component set width and height and preserveAspectRatio="xMinYMin slice"to scale an SVG gradient at your needs.

RecyclerView and java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder in Samsung devices

Problem occured for me only when:

I created the Adapter with an empty list. Then I inserted items and called notifyItemRangeInserted.


I solved this by creating the Adapter only after I have the first chunk of data and initialzing it with it right away. The next chunk could then be inserted and notifyItemRangeInserted called with no problem .

How do I change a tab background color when using TabLayout?

You can change the background color of the tab by this attribute


How to update RecyclerView Adapter Data?

I've solved the same problem in a different way. I don't have data I waiting for it from the background thread so start with an emty list.

        mAdapter = new ModelAdapter(getContext(),new ArrayList<Model>());
   // then when i get data

  //  and update is in my adapter

        public void update(ArrayList<Model> modelList){
            for (Product model: modelList) {

That's it.

How can a divider line be added in an Android RecyclerView?

Kotlin Version:

recyclerview.addItemDecoration(DividerItemDecoration(this, LinearLayoutManager.VERTICAL))

How to use RecyclerView inside NestedScrollView?

if you want to use RecyclerView in NestedScrollView this is a simple tricky, just set :


  • recyclerView.setHasFixedSize(false) (java/kt)

  • android:nestedScrollingEnabled="false"

  • android:layout_height="wrap_content"

  • android:overScrollMode="never"


  • android:fillViewport="true"

this is work for me, and you can use many RecyclerView in NestedScrollView with this too.

Change the color of a checked menu item in a navigation drawer

Here's how you can do it in your Activity's onCreate method:

NavigationView navigationView = findViewById(;
ColorStateList csl = new ColorStateList(
    new int[][] {
        new int[] {-android.R.attr.state_checked}, // unchecked
        new int[] { android.R.attr.state_checked}  // checked
    new int[] {

Error inflating class

Generic way of solving issues like Error inflating class X:

  1. check cause stack trace and there should be Resources$NotFoundException like this:
Caused by: android.content.res.Resources$NotFoundException: Resource ID #0x7f0b0066
    at android.content.res.ResourcesImpl.getValue(
    at android.content.res.Resources.loadXmlResourceParser(
    at android.content.res.Resources.getLayout(
    at android.view.LayoutInflater.inflate(
  1. Resource ID is actually exact integer from generated file.
  2. Find 0x7f0b0066 which will point to the xml file which could not be inflated(found).
  3. In most cases that's because directory layout doesn't have this resource, but some layout-XXX has.
  4. And solution is to put resource into all required directories. Or just at least into layout.

Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference

i had the same problem and it seems like i didn't initiate the button used with click listener, in other words id didn't te

How can I scroll a div to be visible in ReactJS?

With reacts Hooks:

  1. Import
import ReactDOM from 'react-dom';
import React, {useRef} from 'react';
  1. Make new hook:
const divRef = useRef<HTMLDivElement>(null);
  1. Add new Div
<div ref={divRef}/>
  1. Scroll function:
const scrollToDivRef  = () => {
    let node = ReactDOM.findDOMNode(divRef.current) as Element;
    node.scrollIntoView({block: 'start', behavior: 'smooth'});

RecyclerView: Inconsistency detected. Invalid item position

The problem occured on me when I had not recoginized I did call two times with different threads simultaneously .


one from sqlite load function one from after calling function

Vertical rulers in Visual Studio Code

In addition to global "editor.rulers" setting, it's also possible to set this on a per-language level.

For example, style guides for Python projects often specify either 79 or 120 characters vs. Git commit messages should be no longer than 50 characters.

So in your settings.json, you'd put:

"[git-commit]": {"editor.rulers": [50]},
"[python]": {
    "editor.rulers": [

Change the Arrow buttons in Slick slider

Slick has a very easy way to customize its buttons through two variables in its own configuration: prevArrow and nextArrow.

Both types are: string (html | jQuery selector) | object (DOM node | jQuery object), so in your settings slick slider you can set the classes:

prevArrow: $('.prev')
nextArrow: $('.next')

and add to these elements the styles you want.

For example:

<div class="slider-box _clearfix">
    <div class="slick-slider">
            <img src="img/home_carousel/home_carorusel_1.jpg">
            <img src="img/home_carousel/home_carorusel_2.jpg">
            <img src="img/home_carousel/home_carorusel_3.jpg">
            <img src="img/home_carousel/home_carorusel_4.jpg">

<div class="paginator-center text-color text-center">
        <li class="prev"></li>
        <li class="next"></li>

$(document).ready(function () {
      centerMode: true,
      centerPadding: '60px',
      slidesToShow: 3,
      prevArrow: $('.prev'),
      nextArrow: $('.next'),

  position: relative;
  float: right;
  margin-bottom: 20px;

    margin-top: 20px;
    position: relative;
    float: left;

    margin-right: 20px;

      display: block;
      height: 20px;
      width: 20px;
      background: url('../img/back.png') no-repeat;

      display: block;
      height: 20px;
      width: 20px;
      background: url('../img/next.png') no-repeat;

Toolbar overlapping below status bar

Just set this to v21/styles.xml file

 <item name="android:windowDrawsSystemBarBackgrounds">true</item>
 <item name="android:statusBarColor">@color/colorPrimaryDark</item>

and be sure

 <item name="android:windowTranslucentStatus">false</item>

setSupportActionBar toolbar cannot be applied to (android.widget.Toolbar) error

ToolBar's name can easily be changed using

android:label="My Activity"

in your Manifest File. I just going through Manifest & found


Helps to change according to the specific activity, Hope you'll give it a try

How to make custom dialog with rounded corners in android

Create a xml in drawable ,say customd.xml.

then set it at background in your custom Dialog layout xml:


finally in the java part for custom Dialog class you need to do this:

public class Customdialoque extends DialogFragment {

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

    View view = inflater.inflate(R.layout.activity_customdialoque, container, false);

    return view;

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference

in your baseadapter class constructor try to initialize LayoutInflater, normally i preferred this way,

public ClassBaseAdapter(Context context,ArrayList<Integer> listLoanAmount) {
    this.context = context;
    this.listLoanAmount = listLoanAmount;
    this.layoutInflater = LayoutInflater.from(context);

at the top of the class create LayoutInflater variable, hope this will help you

How to center div vertically inside of absolutely positioned parent div

You can do it by using display:table; in parent div and display: table-cell; vertical-align: middle; in child div

<div style="display:table;">_x000D_
      <div style="text-align: left;  height: 56px;  background-color: pink; display: table-cell; vertical-align: middle;">_x000D_
          <div style="background-color: lightblue; ">test</div>_x000D_

Null pointer Exception on .setOnClickListener

Try giving your Button in your main.xml a more descriptive name such as:


(use lowercase in your xml files, at least, the first letter)

And then in your MainActivity class, declare it as:

Button buttonXYZ;

In your onCreate(Bundle savedInstanceState) method, define it as:

buttonXYZ = (Button) findViewById(;

Also, move the Buttons/TextViews outside and place them before the .setOnClickListener - it makes the code cleaner.

Username = (EditText)findViewById(;
CompanyID = (EditText)findViewById(;

The specified child already has a parent. You must call removeView() on the child's parent first (Android)

I was facing the same error, and look what I was doing. My bad, I was trying to add the same view NativeAdView to the multiple FrameLayouts, resolved by creating a separate view NativeAdView for each FrameLayout, Thanks

How to clear/delete the contents of a Tkinter Text widget?

A lot of answers ask you to use END, but if that's not working for you, try:

text.delete("1.0", "end-1c")

Vertical align in bootstrap table

vetrical-align: middle did not work for me for some reason (and it was being applied). I used this:

table.vertical-align > tbody > tr > td {
  display: flex;
  align-items: center;

Programmatically Add CenterX/CenterY Constraints

Center in container

enter image description here

The code below does the same thing as centering in the Interface Builder.

override func viewDidLoad() {

    // set up the view
    let myView = UIView()
    myView.backgroundColor =
    myView.translatesAutoresizingMaskIntoConstraints = false

    // Add code for one of the constraint methods below
    // ...

Method 1: Anchor Style

myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
myView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

Method 2: NSLayoutConstraint Style

NSLayoutConstraint(item: myView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: myView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0).isActive = true


  • Anchor style is the preferred method over NSLayoutConstraint Style, however it is only available from iOS 9, so if you are supporting iOS 8 then you should still use NSLayoutConstraint Style.
  • You will also need to add length and width constraints.
  • My full answer is here.

CardView not showing Shadow in Android L

After going through the docs again, I finally found the solution.

Just add card_view:cardUseCompatPadding="true" to your CardView and shadows will appear on Lollipop devices.

What happens is, the content area in a CardView take different sizes on pre-lollipop and lollipop devices. So in lollipop devices the shadow is actually covered by the card so its not visible. By adding this attribute the content area remains the same across all devices and the shadow becomes visible.

My xml code is like :


Android "elevation" not showing a shadow

Adding background color helped me.




How do I make WRAP_CONTENT work on a RecyclerView

Try this (It's a nasty solution but It may work): In the onCreate method of your Activity or in the onViewCreated method of your fragment. Set a callback ready to be triggered when the RecyclerView first render, like this:

vRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            public void onGlobalLayout() {

In the calculeRecyclerViewFullHeight calculate the RecyclerView full height based in the height of its children.

protected void calculateSwipeRefreshFullHeight() {
        int height = 0;
        for (int idx = 0; idx < getRecyclerView().getChildCount(); idx++ ) {
            View v = getRecyclerView().getChildAt(idx);
            height += v.getHeight();
        SwipeRefreshLayout.LayoutParams params = getSwipeRefresh().getLayoutParams();
        params.height = height;

In my case my RecyclerView is contain in a SwipeRefreshLayout for that reason I'm setting the height to the SwipeRefreshView and not to the RecyclerView but if you don't have any SwipeRefreshView then you can set the height to the RecyclerView instead.

Let me know if this helped you or not.

What's the difference between display:inline-flex and display:flex?

Display:flex apply flex layout to the flex items or children of the container only. So, the container itself stays a block level element and thus takes up the entire width of the screen.

This causes every flex container to move to a new line on the screen.

Display:inline-flex apply flex layout to the flex items or children as well as to the container itself. As a result the container behaves as an inline flex element just like the children do and thus takes up the width required by its items/children only and not the entire width of the screen.

This causes two or more flex containers one after another, displayed as inline-flex, align themselves side by side on the screen until the whole width of the screen is taken.

App crashing when trying to use RecyclerView on android 5.0

If I where you I will do this. onView(withId(; change it to your list id and position will be your position inside your array.

NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference

This issue is due to ArrayList variable not being instantiated. Need to declare "recordings" variable like following, that should solve the issue;

ArrayList<String> recordings = new ArrayList<String>();

this calls default constructor and assigns empty string to the recordings variable so that it is not null anymore.

How to add buttons like refresh and search in ToolBar in Android?

To control the location of the title you may want to set a custom font as explained here (by twaddington): Link

Then to relocate the position of the text, in updateMeasureState() you would add p.baselineShift += (int) (p.ascent() * R); Similarly in updateDrawState() add tp.baselineShift += (int) (tp.ascent() * R); Where R is double between -1 and 1.

Nested Recycler view height doesn't wrap its content

As @yigit mentioned, you need to override onMeasure(). Both @user2302510 and @DenisNek have good answers but if you want to support ItemDecoration you can use this custom layout manager.

And other answers cannot scroll when there are more items than can be displayed on the screen though. This one is using default implemantation of onMeasure() when there are more items than screen size.

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    {
    super(context, orientation, reverseLayout);

private int[] mMeasuredDimension = new int[2];

public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                      int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);
    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {
        measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),

        if (getOrientation() == HORIZONTAL) {
            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
        } else {
            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];

    // If child view is more than screen size, there is no need to make it wrap content. We can use original onMeasure() so we can scroll view.
    if (height < heightSize && width < widthSize) {

        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        setMeasuredDimension(width, height);
    } else {
        super.onMeasure(recycler, state, widthSpec, heightSpec);

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {

   View view = recycler.getViewForPosition(position);

   // For adding Item Decor Insets to view
   super.measureChildWithMargins(view, 0, 0);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight() + getDecoratedLeft(view) + getDecoratedRight(view), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom() + getPaddingBottom() + getDecoratedBottom(view) , p.height);
            view.measure(childWidthSpec, childHeightSpec);

            // Get decorated measurements
            measuredDimension[0] = getDecoratedMeasuredWidth(view) + p.leftMargin + p.rightMargin;
            measuredDimension[1] = getDecoratedMeasuredHeight(view) + p.bottomMargin + p.topMargin;

And if you want to use it with GridLayoutManager just extends it from GridLayoutManager and change

for (int i = 0; i < getItemCount(); i++)


for (int i = 0; i < getItemCount(); i = i + getSpanCount())

No shadow by default on Toolbar?

This worked for me very well:


        android:minHeight="?attr/actionBarSize" />


Error inflating class

I had issues including toolbar in a RelativeLayout, try with LinearLayout. If you want to overlay the toolbar, try with:





I don't understand why but it works for me.

Is there an addHeaderView equivalent for RecyclerView?

HeaderView depends on the LayoutManager. None of the default LayoutManagers support this and probably wont. HeaderView in ListView creates a lot of complexity without any significant benefit.

I would suggest creating a base adapter class that adds items for Headers if provided. Don't forget to override notify* methods to offset them properly depending on whether header is present or not.

Error in styles_base.xml file - android app - No resource found that matches the given name 'android:Widget.Material.ActionButton'

I've just solved these exact errors myself. The key it seems is that your file in your appcompat library project should use whatever the highest version of the API that your particular appcompat project has been written for (in your case it looks like v21). Easiest way I've found to tell is to look for the highest 'values-v**' folder inside the res folder (eg. values-v21).

To clarify, in addition to the instructions at Support Library Setup, your appcompat/ file should have in it: target=android-21 (mine came with 19 instead).

Also ensure that you have the 'SDK Platform' to match that version installed (eg for v21 install Android 5.0 SDK Platform).

See also appcompat-v7:21.0.0': No resource found that matches the given name: attr 'android:actionModeShareDrawable'

Alternatively if you don't want to use the appcompat at all, (I think) all you need to do is right click your project > Properties > Android > Library > Remove the reference to the appcompat. The errors will still show up for the appcompat project, but shouldn't affect your project after that.

Toolbar navigation icon never set

Currently you can use it, changing the order: (it seems to be a bug)

Toolbar toolbar = (Toolbar) findViewById(;


In android app Toolbar.setTitle method has no effect – application name is shown as title

Found the solution:

Instead of:

mActionBarToolbar = (Toolbar) findViewById(;            
mActionBarToolbar.setTitle("My title");

I used:

mActionBarToolbar = (Toolbar) findViewById(;            
getSupportActionBar().setTitle("My title");

And it works.

Android RecyclerView addition & removal of items

make interface into custom adapter class and handling click event on recycler view..

 onItemClickListner onItemClickListner;

public void setOnItemClickListner(CommentsAdapter.onItemClickListner onItemClickListner) {
    this.onItemClickListner = onItemClickListner;

public interface onItemClickListner {
    void onClick(Contact contact);//pass your object types.
public void onBindViewHolder(ItemViewHolder holder, int position) {
    // below code handle click event on recycler view item.
    holder.itemView.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {

after define adapter and bind into recycler view called below code..

        adapter.setOnItemClickListner(new CommentsAdapter.onItemClickListner() {
        public void onClick(Contact contact) {

How to make a view with rounded corners?

public class RoundedCornerLayout extends FrameLayout {
    private double mCornerRadius;

    public RoundedCornerLayout(Context context) {
        this(context, null, 0);

    public RoundedCornerLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);

    public RoundedCornerLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs, defStyle);

    private void init(Context context, AttributeSet attrs, int defStyle) {
        DisplayMetrics metrics = context.getResources().getDisplayMetrics();
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);

    public double getCornerRadius() {
        return mCornerRadius;

    public void setCornerRadius(double cornerRadius) {
        mCornerRadius = cornerRadius;

    public void draw(Canvas canvas) {
        int count =;

        final Path path = new Path();
        path.addRoundRect(new RectF(0, 0, canvas.getWidth(), canvas.getHeight()), (float) mCornerRadius, (float) mCornerRadius, Path.Direction.CW);
        canvas.clipPath(path, Region.Op.REPLACE);


UICollectionView Self Sizing Cells with Auto Layout

I did a dynamic cell height of collection view. Here is git hub repo.

And, dig out why preferredLayoutAttributesFittingAttributes is called more than once. Actually, it will be called at least 3 times.

The console log picture : enter image description here

1st preferredLayoutAttributesFittingAttributes:

(lldb) po layoutAttributes
<UICollectionViewLayoutAttributes: 0x7fa405c290e0> index path: (<NSIndexPath:    0xc000000000000016> 
{length = 2, path = 0 - 0}); frame = (15 12; 384 57.5); 

(lldb) po self.collectionView
<UICollectionView: 0x7fa40606c800; frame = (0 57.6667; 384 0);

The layoutAttributes.frame.size.height is current status 57.5.

2nd preferredLayoutAttributesFittingAttributes:

(lldb) po layoutAttributes
<UICollectionViewLayoutAttributes: 0x7fa405c16370> index path: (<NSIndexPath: 0xc000000000000016> 
{length = 2, path = 0 - 0}); frame = (15 12; 384 534.5); 

(lldb) po self.collectionView
<UICollectionView: 0x7fa40606c800; frame = (0 57.6667; 384 0);

The cell frame height changed to 534.5 as our expected. But, the collection view still zero height.

3rd preferredLayoutAttributesFittingAttributes:

(lldb) po layoutAttributes
<UICollectionViewLayoutAttributes: 0x7fa403d516a0> index path: (<NSIndexPath: 0xc000000000000016> 
{length = 2, path = 0 - 0}); frame = (15 12; 384 534.5); 

(lldb) po self.collectionView
<UICollectionView: 0x7fa40606c800; frame = (0 57.6667; 384 477);

You can see the collection view height was changed from 0 to 477.

The behavior is similar to handle scroll:

1. Before self-sizing cell

2. Validated self-sizing cell again after other cells recalculated.

3. Did changed self-sizing cell

At beginning, I thought this method only call once. So I coded as the following:

CGRect frame = layoutAttributes.frame;
frame.size.height = frame.size.height + self.collectionView.contentSize.height;
UICollectionViewLayoutAttributes* newAttributes = [layoutAttributes copy];
newAttributes.frame = frame;
return newAttributes;

This line:

frame.size.height = frame.size.height + self.collectionView.contentSize.height;

will cause system call infinite loop and App crash.

Any size changed, it will validate all cells' preferredLayoutAttributesFittingAttributes again and again until every cells' positions (i.e frames) are no more change.

CSS flexbox vertically/horizontally center image WITHOUT explicitely defining parent height

Just add the following rules to the parent element:

display: flex;
justify-content: center; /* align horizontal */
align-items: center; /* align vertical */

Here's a sample demo (Resize window to see the image align)

Browser support for Flexbox nowadays is quite good.

For cross-browser compatibility for display: flex and align-items, you can add the older flexbox syntax as well:

display: -webkit-box;
display: -webkit-flex;
display: -moz-box;
display: -ms-flexbox;
display: flex;
-webkit-flex-align: center;
-ms-flex-align: center;
-webkit-align-items: center;
align-items: center;

Bootstrap how to get text to vertical align in a div container


First, we will need to add a class to your text container so that we can access and style it accordingly.

<div class="col-xs-5 textContainer">
     <h3 class="text-left">Link up with other gamers all over the world who share the same tastes in games.</h3>


Next, we will apply the following styles to align it vertically, according to the size of the image div next to it.

.textContainer { 
    height: 345px; 
    line-height: 340px;

.textContainer h3 {
    vertical-align: middle;
    display: inline-block;

All Done! Adjust the line-height and height on the styles above if you believe that it is still slightly out of align.


Unity 2d jumping script

Usually for jumping people use Rigidbody2D.AddForce with Forcemode.Impulse. It may seem like your object is pushed once in Y axis and it will fall down automatically due to gravity.


rigidbody2D.AddForce(new Vector2(0, 10), ForceMode2D.Impulse);

How to vertically align text inside a flexbox?

Instead of using align-self: center use align-items: center.

There's no need to change flex-direction or use text-align.

Here's your code, with one adjustment, to make it all work:

ul {
  height: 100%;

li {
  display: flex;
  justify-content: center;
  /* align-self: center;    <---- REMOVE */
  align-items: center;   /* <---- NEW    */
  background: silver;
  width: 100%;
  height: 20%; 

The align-self property applies to flex items. Except your li is not a flex item because its parent – the ul – does not have display: flex or display: inline-flex applied.

Therefore, the ul is not a flex container, the li is not a flex item, and align-self has no effect.

The align-items property is similar to align-self, except it applies to flex containers.

Since the li is a flex container, align-items can be used to vertically center the child elements.

* {_x000D_
  padding: 0;_x000D_
  margin: 0;_x000D_
html, body {_x000D_
  height: 100%;_x000D_
ul {_x000D_
  height: 100%;_x000D_
li {_x000D_
  display: flex;_x000D_
  justify-content: center;_x000D_
  /* align-self: center; */_x000D_
  align-items: center;_x000D_
  background: silver;_x000D_
  width: 100%;_x000D_
  height: 20%;_x000D_
  <li>This is the text</li>_x000D_

codepen demo

Technically, here's how align-items and align-self work...

The align-items property (on the container) sets the default value of align-self (on the items). Therefore, align-items: center means all flex items will be set to align-self: center.

But you can override this default by adjusting the align-self on individual items.

For example, you may want equal height columns, so the container is set to align-items: stretch. However, one item must be pinned to the top, so it is set to align-self: flex-start.


How is the text a flex item?

Some people may be wondering how a run of text...

<li>This is the text</li>

is a child element of the li.

The reason is that text that is not explicitly wrapped by an inline-level element is algorithmically wrapped by an inline box. This makes it an anonymous inline element and child of the parent.

From the CSS spec: Anonymous inline boxes

Any text that is directly contained inside a block container element must be treated as an anonymous inline element.

The flexbox specification provides for similar behavior.

4. Flex Items

Each in-flow child of a flex container becomes a flex item, and each contiguous run of text that is directly contained inside a flex container is wrapped in an anonymous flex item.

Hence, the text in the li is a flex item.

Android: Creating a Circular TextView?

The typical solution is to define the shape and use it as background but as the number of digits varies it's no more a perfect circle, it looks like a rectangle with round edges or Oval. So I have developed this solution, it's working great. Hope it will help someone.

Circular Text View

Here is the code of custom TextView

import android.content.Context;
import android.util.AttributeSet;
import android.widget.TextView;

public class CircularTextView extends TextView
private float strokeWidth;
int strokeColor,solidColor;

public CircularTextView(Context context) {

public CircularTextView(Context context, AttributeSet attrs) {
    super(context, attrs);

public CircularTextView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

public void draw(Canvas canvas) {

    Paint circlePaint = new Paint();

    Paint strokePaint = new Paint();

    int  h = this.getHeight();
    int  w = this.getWidth();

    int diameter = ((h > w) ? h : w);
    int radius = diameter/2;


    canvas.drawCircle(diameter / 2 , diameter / 2, radius, strokePaint);

    canvas.drawCircle(diameter / 2, diameter / 2, radius-strokeWidth, circlePaint);


public void setStrokeWidth(int dp)
    float scale = getContext().getResources().getDisplayMetrics().density;
    strokeWidth = dp*scale;


public void setStrokeColor(String color)
    strokeColor = Color.parseColor(color);

public void setSolidColor(String color)
    solidColor = Color.parseColor(color);


Then in your XML, give some padding and make sure its gravity is center


And you can set the stroke width


Fill remaining vertical space with CSS using display:flex

Here is the codepen demo showing the solution:

Important highlights:

  • all containers from html, body, ... .container, should have the height set to 100%
  • introducing flex to ANY of the flex items will trigger calculation of the items sizes based on flex distribution:
    • if only one cell is set to flex, for example: flex: 1 then this flex item will occupy the remaining of the space
    • if there are more than one with the flex property, the calculation will be more complicated. For example, if the item 1 is set to flex: 1 and the item 2 is se to flex: 2 then the item 2 will take twice more of the remaining space
  • Main Size Property

Column/Vertical selection with Keyboard in SublimeText 3

This should do it:

  1. Ctrl+A - select all.
  2. Ctrl+Shift+L - split selection into lines.
  3. Then move all cursors with left/right, select with Shift+left/right. Move all cursors to start of line with Home.

Flexbox not giving equal width to elements

There is an important bit that is not mentioned in the article to which you linked and that is flex-basis. By default flex-basis is auto.

From the spec:

If the specified flex-basis is auto, the used flex basis is the value of the flex item’s main size property. (This can itself be the keyword auto, which sizes the flex item based on its contents.)

Each flex item has a flex-basis which is sort of like its initial size. Then from there, any remaining free space is distributed proportionally (based on flex-grow) among the items. With auto, that basis is the contents size (or defined size with width, etc.). As a result, items with bigger text within are being given more space overall in your example.

If you want your elements to be completely even, you can set flex-basis: 0. This will set the flex basis to 0 and then any remaining space (which will be all space since all basises are 0) will be proportionally distributed based on flex-grow.

li {
    flex-grow: 1;
    flex-basis: 0;
    /* ... */

This diagram from the spec does a pretty good job of illustrating the point.

And here is a working example with your fiddle.

Scrolling to an Anchor using Transition/CSS3

While some of the answers were very useful and informative, I thought I would write down the answer I came up with. The answer from Alex was very good, it is however limited in the sense that the height of the div needs to be hard coded in the CSS.

So the solution I came up with uses JS (no jQuery) and is actually a stripped down version (almost to the minimum) of over solutions to solve similar problems I found on Statckoverflow:


<div class="header">
    <p class="menu"><a href="#S1" onclick="test('S1'); return false;">S1</a></p>
    <p class="menu"><a href="#S2" onclick="test('S2'); return false;">S2</a></p>
    <p class="menu"><a href="#S3" onclick="test('S3'); return false;">S3</a></p>
    <p class="menu"><a href="#S4" onclick="test('S4'); return false;">S3</a></p>
<div style="width: 100%;">
    <div id="S1" class="curtain">
    <div id="S2" class="curtain">
    <div id="S3" class="curtain">
    <div id="S4" class="curtain">

NOTE THE "RETURN FALSE;" in the on click call. This is important if you want to avoid having your browser jumping to the link itself (and let the effect being managed by your JS).

JS code:

function scrollTo(to, duration) {
    if (document.body.scrollTop == to) return;
    var diff = to - document.body.scrollTop;
    var scrollStep = Math.PI / (duration / 10);
    var count = 0, currPos;
    start = element.scrollTop;
    scrollInterval = setInterval(function(){
        if (document.body.scrollTop != to) {
            count = count + 1;
            currPos = start + diff * (0.5 - 0.5 * Math.cos(count * scrollStep));
            document.body.scrollTop = currPos;
        else { clearInterval(scrollInterval); }

function test(elID)
    var dest = document.getElementById(elID);
    scrollTo(dest.offsetTop, 500);

It's incredibly simple. It finds the vertical position of the div in the document using its unique ID (in the function test). Then it calls the scrollTo function passing the starting position (document.body.scrollTop) and the destination position (dest.offsetTop). It performs the transition using some sort of ease-inout curve.

Thanks everyone for your help.

Knowing a bit of coding can help you avoiding (sometimes heavy) libraries, and giving you (the programmer) more control.

How to include a font .ttf using CSS?

Only providing .ttf file for webfont won't be good enough for cross-browser support. The best possible combination at present is using the combination as :

@font-face {
  font-family: 'MyWebFont';
  src: url('webfont.eot'); /* IE9 Compat Modes */
  src: url('webfont.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
       url('webfont.woff') format('woff'), /* Modern Browsers */
       url('webfont.ttf')  format('truetype'), /* Safari, Android, iOS */
       url('webfont.svg#svgFontName') format('svg'); /* Legacy iOS */

This code assumes you have .eot , .woff , .ttf and svg format for you webfont. To automate all this process , you can use :

Also , modern browsers are shifting towards .woff font , so you can probably do this too : :

@font-face {
  font-family: 'MyWebFont';
  src: url('myfont.woff') format('woff'), /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
   url('myfont.ttf') format('truetype'); /* Chrome 4+, Firefox 3.5, Opera 10+, Safari 3—5 */

Read more here :

Look for browser support : Can I Use fontface

How to draw vertical lines on a given plot in matplotlib

matplotlib.pyplot.vlines vs. matplotlib.pyplot.axvline

  • The difference is that vlines accepts 1 or more locations for x, while axvline permits one location.
    • Single location: x=37
    • Multiple locations: x=[37, 38, 39]
  • vlines takes ymin and ymax as a position on the y-axis, while axvline takes ymin and ymax as a percentage of the y-axis range.
    • When passing multiple lines to vlines, pass a list to ymin and ymax.
  • If you're plotting a figure with something like fig, ax = plt.subplots(), then replace plt.vlines or plt.axvline with ax.vlines or ax.axvline, respectively.
import numpy as np
import matplotlib.pyplot as plt

xs = np.linspace(1, 21, 200)

plt.figure(figsize=(10, 7))

# only one line may be specified; full height
plt.axvline(x=36, color='b', label='axvline - full height')

# only one line may be specified; ymin & ymax spedified as a percentage of y-range
plt.axvline(x=36.25, ymin=0.05, ymax=0.95, color='b', label='axvline - % of full height')

# multiple lines all full height
plt.vlines(x=[37, 37.25, 37.5], ymin=0, ymax=len(xs), colors='purple', ls='--', lw=2, label='vline_multiple - full height')

# multiple lines with varying ymin and ymax
plt.vlines(x=[38, 38.25, 38.5], ymin=[0, 25, 75], ymax=[200, 175, 150], colors='teal', ls='--', lw=2, label='vline_multiple - partial height')

# single vline with full ymin and ymax
plt.vlines(x=39, ymin=0, ymax=len(xs), colors='green', ls=':', lw=2, label='vline_single - full height')

# single vline with specific ymin and ymax
plt.vlines(x=39.25, ymin=25, ymax=150, colors='green', ls=':', lw=2, label='vline_single - partial height')

# place legend outside
plt.legend(bbox_to_anchor=(1.0, 1), loc='upper left')

enter image description here

iOS 8 removed "minimal-ui" viewport property, are there other "soft fullscreen" solutions?

It is possible to get a web application running in full screen in both iOS and Android, it is called a PWA and after mucha hard work, it was the only way around this issue.

PWAs open a number of interesting options for development that should not be missed. I've made a couple already, check out this Public and Private Tender Manual For Designers (Spanish). And here is an English explanation from the CosmicJS site

Why is it that "No HTTP resource was found that matches the request URI" here?

You need to map the unique route to specify your parameters as query elements. In RouteConfig.cs (or WebApiConfig.cs) add:

            name: "MyPagedQuery",
            routeTemplate:     "api/{controller}/{action}/{firstId}/{countToFetch}",
            defaults: new { action = "GetNDepartmentsFromID" }

How do I force a vertical scrollbar to appear?

html { overflow-y: scroll; }

This css rule causes a vertical scrollbar to always appear.


How to add dividers and spaces between items in RecyclerView?

1.One of the Way is by using cardview and recycler view together we can easily add effect like divider. ex.

2.and other is by adding view as divider to list_item_layout of recycler view.

            android:background="@color/colorAccent" />

In Bootstrap 3,How to change the distance between rows in vertical?

Instead of adding any tag which is never a good solution. You can always use margin property with the required element.

You can add the margin on row class itself. So it will affect globally.

  margin-top: 30px;
  margin-bottom: 30px

Update: Better solution in all cases would be to introduce a new class and then use it along with .row class.

  margin-top : 20px

Then use it wherever you want

<div class="row row-m-t"></div>

How to check if a view controller is presented modally or pushed on a navigation stack?

In Swift:

Add a flag to test if it's a modal by the class type:

// MARK: - UIViewController implementation

extension UIViewController {

    var isModal: Bool {

        let presentingIsModal = presentingViewController != nil
        let presentingIsNavigation = navigationController?.presentingViewController?.presentedViewController == navigationController
        let presentingIsTabBar = tabBarController?.presentingViewController is UITabBarController

        return presentingIsModal || presentingIsNavigation || presentingIsTabBar

Fill remaining vertical space - only CSS

You can use CSS Flexbox instead another display value, The Flexbox Layout (Flexible Box) module aims at providing a more efficient way to lay out, align and distribute space among items in a container, even when their size is unknown and/or dynamic.


    display: -webkit-box; /* OLD - iOS 6-, Safari 3.1-6 */
    display: -moz-box; /* OLD - Firefox 19- (buggy but mostly works) */
    display: -ms-flexbox; /* TWEENER - IE 10 */
    display: -webkit-flex; /* NEW - Chrome */
    display: flex; /* NEW, Spec - Opera 12.1, Firefox 20+ */
    -ms-flex-direction: column;
    -moz-flex-direction: column;
    -webkit-flex-direction: column;
    flex-direction: column;

    height: 200px;


   background-color: #9ACD32;
    -webkit-box-flex: 1; /* OLD - iOS 6-, Safari 3.1-6 */
    -moz-box-flex: 1; /* OLD - Firefox 19- */
    -webkit-flex: 1; /* Chrome */
    -ms-flex: 1; /* IE 10 */
    flex: 1; /* NEW, */

jsfiddle Example

If you want to have full support for old browsers like IE9 or below, you will have to use a polyfills like flexy, this polyfill enable support for Flexbox model but only for 2012 spec of flexbox model.

Recently I found another polyfill to help you with Internet Explorer 8 & 9 or any older browser that not have support for flexbox model, I still have not tried it but I leave the link here

You can find a usefull and complete Guide to Flexbox model by Chris Coyer here

How can I change the width and height of slides on Slick Carousel?

I know there is already an answer to this but I just found a better solution using the variableWidth parameter, just set it to true in the settings of each breakpoint, like this:

  arrows: true,
  autoplay: true,
  autoplaySpeed: 3000,
  dots: true,
  draggable: false,
  fade: true,
  infinite: false,
  responsive: [
    breakpoint: 620,
    settings: {
        arrows: true,
        variableWidth: true
    breakpoint: 345,
    settings: {
        arrows: true,
        variableWidth: true

How can I make my flexbox layout take 100% vertical space?

Let me show you another way that works 100%. I will also add some padding for the example.

<div class = "container">
  <div class = "flex-pad-x">
    <div class = "flex-pad-y">
      <div class = "flex-pad-y">
        <div class = "flex-grow-y">
         Content Centered

.container {
  position: fixed;
  top: 0px;
  left: 0px;
  bottom: 0px;
  right: 0px;
  width: 100%;
  height: 100%;

  .flex-pad-x {
    padding: 0px 20px;
    height: 100%;
    display: flex;

  .flex-pad-y {
    padding: 20px 0px;
    width: 100%;
    display: flex;
    flex-direction: column;

  .flex-grow-y {
    flex-grow: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;

As you can see we can achieve this with a few wrappers for control while utilising the flex-grow & flex-direction attribute.

1: When the parent "flex-direction" is a "row", its child "flex-grow" works horizontally. 2: When the parent "flex-direction" is "columns", its child "flex-grow" works vertically.

Hope this helps


Android button with icon and text

You can use the Material Components Library and the MaterialButton component.
Use the app:icon and app:iconGravity="start" attributes.

Something like:


enter image description here

Bootstrap push div content to new line

Do a row div.

Like this:

<link href="" rel="stylesheet" integrity="sha384-Zug+QiDoJOrZ5t4lssLdxGhVrurbmBWopoEl+M6BdEfwnCJZtKxi1KgxUyJq13dy" crossorigin="anonymous">_x000D_
<div class="grid">_x000D_
    <div class="row">_x000D_
        <div class="col-lg-3 col-md-3 col-sm-3 col-xs-12 bg-success">Under me should be a DIV</div>_x000D_
        <div class="col-lg-6 col-md-6 col-sm-5 col-xs-12 bg-danger">Under me should be a DIV</div>_x000D_
    <div class="row">_x000D_
        <div class="col-lg-3 col-md-3 col-sm-4 col-xs-12 bg-warning">I am the last DIV</div>_x000D_

How to make div same height as parent (displayed as table-cell)

You have to set the height for the parents (container and child) explicitly, here is another work-around (if you don't want to set that height explicitly):

.child {
  width: 30px;
  background-color: red;
  display: table-cell;
  vertical-align: top;

.content {
  background-color: blue;


CSS : center form in page horizontally and vertically

The accepted answer didn't work with my form, even when I stripped it down to the bare minimum and copied & pasted the code. If anyone else is having this problem, please give my solution a try. Basically, you set Top and Left to 50% as the OP did, but offset the form's container with negative margins on the top and left equal to 50% of the div's height and width, respectively. This moves the center point of the Top and Left coordinates to the center of the form. I will stress that the height and width of the form must be specified (not relative). In this example, a 300x300px form div with margins of -150px on the top and left is perfectly centered no matter the window size:


    <div class="login_div">
        <form class="login_form" action="#">


.login_div {
    position: absolute;

    width: 300px;
    height: 300px;

    /* Center form on page horizontally & vertically */
    top: 50%;
    left: 50%;
    margin-top: -150px;
    margin-left: -150px;

.login_form {
    width: 300px;
    height: 300px;

    background: gray;
    border-radius: 10px;

    margin: 0;
    padding: 0;


Now, for those wondering why I used a container for the form, it's because I like to have the option of placing other elements in the form's vicinity and having them centered as well. The form container is completely unnecessary in this example, but would definitely be useful in other cases. Hope this helps!

Couldn't load memtrack module Logcat Error

I faced the same problem but When I changed the skin of AVD device to HVGA, it worked.

How to vertically align text with icon font?

vertical-align can take a unit value so you can resort to that when needed:

  vertical-align: 5px;

  vertical-align: -5px;

Move div to new line

What about something like this.

<div id="movie_item">
    <div class="movie_item_poster">
        <img src="..." style="max-width: 100%; max-height: 100%;">

     <div id="movie_item_content">
        <div class="movie_item_content_year">year</div>
        <div class="movie_item_content_title">title</div>
        <div class="movie_item_content_plot">plot</div>

    <div class="movie_item_toolbar">
        Lorem Ipsum...

You don't have to float both movie_item_poster AND movie_item_content. Just float one of them...

#movie_item {
    position: relative;
    margin-top: 10px;
    height: 175px;

.movie_item_poster {
    float: left;
    height: 150px;
    width: 100px;

.movie_item_content {
    position: relative;

.movie_item_content_title {

.movie_item_content_year {
    float: right;

.movie_item_content_plot {

.movie_item_toolbar {
    clear: both;
    vertical-align: bottom;
    width: 100%;
    height: 25px;

Here it is as a JSFiddle.

Android adding simple animations while setvisibility(view.Gone)

I was able to show/hide a menu this way: (extends FrameLayout)

private final int ANIMATION_DURATION = 500;

public void showMenu()

private void hideMenu()
            .setListener(new AnimatorListenerAdapter() {
                public void onAnimationEnd(Animator animation) {


Python FileNotFound

try block should be around open. Not around prompt.

while True:
    prompt = input("\n Hello to Sudoku valitator,"
    "\n \n Please type in the path to your file and press 'Enter': ")
        sudoku = open(prompt, 'r').readlines()
    except FileNotFoundError:
        print("Wrong file or file path")

height: 100% for <div> inside <div> with display: table-cell


table > td{

table > td > .inner{

Confirmed working on:

  • Chrome 60.0.3112.113, 63.0.3239.84
  • Firefox 55.0.3, 57.0.1
  • Internet Explorer 11

How to vertically center a container in Bootstrap?

If you're using Bootstrap 4, you just have to add 2 divs:

<script src=""></script>    _x000D_
<script src=""></script>_x000D_
<link href="" rel="stylesheet"/>_x000D_
  <div class="jumbotron">_x000D_
    <div class="d-table w-100 h-100">_x000D_
      <div class="d-table-cell w-100 h-100 align-middle">_x000D_
          your stuff..._x000D_
        <div class="container">_x000D_
          <div class="row">_x000D_
            <div class="col-12">_x000D_
                More stuff..._x000D_

The classes: d-table, d-table-cell, w-100, h-100 and align-middle will do the job

Detect merged cells in VBA Excel with MergeArea

There are several helpful bits of code for this.

Place your cursor in a merged cell and ask these questions in the Immidiate Window:

Is the activecell a merged cell?

? Activecell.Mergecells

How many cells are merged?

? Activecell.MergeArea.Cells.Count

How many columns are merged?

? Activecell.MergeArea.Columns.Count

How many rows are merged?

? Activecell.MergeArea.Rows.Count

What's the merged range address?

? activecell.MergeArea.Address

CSS how to make scrollable list

As per your question vertical listing have a scrollbar effect.


nav ul{height:200px; width:18%;}_x000D_
nav ul{overflow:hidden; overflow-y:scroll;}
<!DOCTYPE html>_x000D_
        <meta charset="utf-8">_x000D_
        <title>JS Bin</title>_x000D_
        <header>header area</header>_x000D_
                <li>Link 1</li>_x000D_
                <li>Link 2</li>_x000D_
                <li>Link 3</li>_x000D_
                <li>Link 4</li>_x000D_
                <li>Link 5</li>_x000D_
                <li>Link 6</li> _x000D_
                <li>Link 7</li> _x000D_
                <li>Link 8</li>_x000D_
                <li>Link 9</li>_x000D_
                <li>Link 10</li>_x000D_
                <li>Link 11</li>_x000D_
                <li>Link 13</li>_x000D_
                <li>Link 13</li>_x000D_
        <footer>footer area</footer>_x000D_

Concatenate two NumPy arrays vertically

If the actual problem at hand is to concatenate two 1-D arrays vertically, and we are not fixated on using concatenate to perform this operation, I would suggest the use of np.column_stack:

In []: a = np.array([1,2,3])
In []: b = np.array([4,5,6])
In []: np.column_stack((a, b))
array([[1, 4],
       [2, 5],
       [3, 6]])

Binding an Image in WPF MVVM

Displaying an Image in WPF is much easier than that. Try this:

<Image Source="{Binding DisplayedImagePath}" HorizontalAlignment="Left" 
    Margin="0,0,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Bottom" 
    Grid.Row="8" Width="200"  Grid.ColumnSpan="2" />

And the property can just be a string:

public string DisplayedImage 
    get { return @"C:\Users\Public\Pictures\Sample Pictures\Chrysanthemum.jpg"; }

Although you really should add your images to a folder named Images in the root of your project and set their Build Action to Resource in the Properties Window in Visual Studio... you could then access them using this format:

public string DisplayedImage 
    get { return "/AssemblyName;component/Images/ImageName.jpg"; }


As a final tip... if you ever have a problem with a control not working as expected, simply type 'WPF', the name of that control and then the word 'class' into a search engine. In this case, you would have typed 'WPF Image Class'. The top result will always be MSDN and if you click on the link, you'll find out all about that control and most pages have code examples as well.

UPDATE 2 >>>

If you followed the examples from the link to MSDN and it's not working, then your problem is not the Image control. Using the string property that I suggested, try this:

    <Image Source="{Binding DisplayedImagePath}" />
    <TextBlock Text="{Binding DisplayedImagePath}" />

If you can't see the file path in the TextBlock, then you probably haven't set your DataContext to the instance of your view model. If you can see the text, then the problem is with your file path.

UPDATE 3 >>>

In .NET 4, the above Image.Source values would work. However, Microsoft made some horrible changes in .NET 4.5 that broke many different things and so in .NET 4.5, you'd need to use the full pack path like this:

<Image Source="pack://application:,,,/AssemblyName;component/Images/image_to_use.png">

For further information on pack URIs, please see the Pack URIs in WPF page on Microsoft Docs.

TypeError: got multiple values for argument

This happens when a keyword argument is specified that overwrites a positional argument. For example, let's imagine a function that draws a colored box. The function selects the color to be used and delegates the drawing of the box to another function, relaying all extra arguments.

def color_box(color, *args, **kwargs):
    painter.draw_box(*args, **kwargs)

Then the call

color_box("blellow", color="green", height=20, width=30)

will fail because two values are assigned to color: "blellow" as positional and "green" as keyword. (painter.draw_box is supposed to accept the height and width arguments).

This is easy to see in the example, but of course if one mixes up the arguments at call, it may not be easy to debug:

# misplaced height and width
color_box(20, 30, color="green")

Here, color is assigned 20, then args=[30] and color is again assigned "green".

Button button = findViewById( always resolves to null in Android Studio is not part of R.layout.activity_main. How should the activity find it in the content view?

The layout that contains the button is displayed by the Fragment, so you have to get the Button there, in the Fragment.

Reactjs - setting inline styles correctly

Correct and more clear way is :

<div style={{"font-size" : "10px", "height" : "100px", "width" : "100%"}}> My inline Style </div>

It is made more simple by following approach :

// JS
const styleObject = {
      "font-size" : "10px",
      "height" : "100px",
      "width" : "100%"

// HTML    
<div style={styleObject}> My inline Style </div>

Inline style attribute expects object. Hence its written in {}, and it becomes double {{}} as one is for default react standards.

Bootstrap 3 Horizontal and Vertical Divider

Do you have to use Bootstrap for this? Here's a basic HTML/CSS example for obtaining this look that doesn't use any Bootstrap:


<div class="bottom">
    <div class="box-content right">Rich Media Ad Production</div>
    <div class="box-content right">Web Design & Development</div>
    <div class="box-content right">Mobile Apps Development</div>
    <div class="box-content">Creative Design</div>
    <div class="box-content right">Web Analytics</div>
    <div class="box-content right">Search Engine Marketing</div>
    <div class="box-content right">Social Media</div>
    <div class="box-content">Quality Assurance</div>


.box-content {
    display: inline-block;
    width: 200px;
    padding: 10px;

.bottom {
    border-bottom: 1px solid #ccc;

.right {
    border-right: 1px solid #ccc;

Here is the working Fiddle.


If you must use Bootstrap, here is a semi-responsive example that achieves the same effect, although you may need to write a few additional media queries.


<div class="row">
    <div class="col-xs-3">Rich Media Ad Production</div>
    <div class="col-xs-3">Web Design & Development</div>
    <div class="col-xs-3">Mobile Apps Development</div>
    <div class="col-xs-3">Creative Design</div>
<div class="row">
    <div class="col-xs-3">Web Analytics</div>
    <div class="col-xs-3">Search Engine Marketing</div>
    <div class="col-xs-3">Social Media</div>
    <div class="col-xs-3">Quality Assurance</div>


.row:not(:last-child) {
    border-bottom: 1px solid #ccc;

.col-xs-3:not(:last-child) {
    border-right: 1px solid #ccc;

Here is another working Fiddle.


Note that you may also use the <hr> element to insert a horizontal divider in Bootstrap as well if you'd like.

Onclick CSS button effect

You should apply the following styles:

#button:active {
    vertical-align: top;
    padding: 8px 13px 6px;

This will give you the necessary effect, demo here.

Example on ToggleButton

public void onClick(View v) {
    // TODO Auto-generated method stub
    editString = ed.getText().toString();

        toggle.setTextOff("TOGGLE ON");

    else if(editString.equals("0")){

        toggle.setTextOn("TOGGLE OFF");


Android Fragment onClick button Method

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.writeqrcode_main, container, false);
    // Inflate the layout for this fragment

    txt_name = (TextView) view.findViewById(;
    txt_usranme = (TextView) view.findViewById(;
    txt_number = (TextView) view.findViewById(;
    txt_province = (TextView) view.findViewById(;
    txt_write = (EditText) view.findViewById(;
    txt_show1 = (Button) view.findViewById(;

    txt_show1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {

    return view;

You OK !!!!

Responsive timeline UI with Bootstrap3

"Timeline (responsive)" snippet:

This looks very, very close to what your example shows. The bootstrap snippet linked below covers all the bases you are looking for. I've been considering it myself, with the same requirements you have ( especially responsiveness ). This morphs well between screen sizes and devices.

You can fork this and use it as a great starting point for your specific expectations:

Here are two screenshots I took for you... wide and thin:

wide thin

Properly embedding Youtube video into bootstrap 3.0 page

I use bootstrap 3.x as well and the following code fore responsive youtube video embedding works like charm for me:

.videoWrapperOuter {
.videoWrapperInner {
  float: none;
  clear: both;
  width: 100%;
  position: relative;
  padding-bottom: 50%;
  padding-top: 25px;
  height: 0;
.videoWrapperInner iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
<div class="videoWrapperOuter">
  <div class="videoWrapperInner">
    <iframe src="//" 
      frameborder="0" allowfullscreen></iframe>

I gave a similiar answer on another thread (Shrink a YouTube video to responsive width), but I guess my answers can help here as well.

ImageView rounded corners

I use extend ImageView:

public class RadiusCornerImageView extends {
    private int cornerRadiusDP = 0; // dp
    private int corner_radius_position;

    public RadiusCornerImageView(Context context) {

    public RadiusCornerImageView(Context context, AttributeSet attrs) {
        super(context, attrs);

    public RadiusCornerImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray typeArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.RadiusCornerImageView, 0, 0);
        try {
            cornerRadiusDP = typeArray.getInt(R.styleable.RadiusCornerImageView_corner_radius_dp, 0);
            corner_radius_position = typeArray.getInteger(R.styleable.RadiusCornerImageView_corner_radius_position, 0);
        } finally {

    protected void onDraw(Canvas canvas) {
        float radiusPx = AndroidUtil.dpToPx(getContext(), cornerRadiusDP);
        Path clipPath = new Path();
        RectF rect = null;
        if (corner_radius_position == 0) { // all
            // round corners on all 4 angles
            rect = new RectF(0, 0, this.getWidth(), this.getHeight());
        } else if (corner_radius_position == 1) {
            // round corners only on top left and top right
            rect = new RectF(0, 0, this.getWidth(), this.getHeight() + radiusPx);
         } else {
            throw new IllegalArgumentException("Unknown corner_radius_position = " + corner_radius_position);
        clipPath.addRoundRect(rect, radiusPx, radiusPx, Path.Direction.CW);

Maintain aspect ratio of div but fill screen width and height in CSS?

Use the new CSS viewport units vw and vh (viewport width / viewport height)


Resize vertically and horizontally and you'll see that the element will always fill the maximum viewport size without breaking the ratio and without scrollbars!


    width: 100vw; 
    height: 56.25vw; /* height:width ratio = 9/16 = .5625  */
    background: pink;
    max-height: 100vh;
    max-width: 177.78vh; /* 16/9 = 1.778 */
    margin: auto;
    position: absolute;
    top:0;bottom:0; /* vertical center */
    left:0;right:0; /* horizontal center */

* {_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
div {_x000D_
  width: 100vw;_x000D_
  height: 56.25vw;_x000D_
  /* 100/56.25 = 1.778 */_x000D_
  background: pink;_x000D_
  max-height: 100vh;_x000D_
  max-width: 177.78vh;_x000D_
  /* 16/9 = 1.778 */_x000D_
  margin: auto;_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  bottom: 0;_x000D_
  /* vertical center */_x000D_
  left: 0;_x000D_
  right: 0;_x000D_
  /* horizontal center */_x000D_

If you want to use a maximum of say 90% width and height of the viewport: FIDDLE

* {_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
div {_x000D_
  width: 90vw;_x000D_
  /* 90% of viewport vidth */_x000D_
  height: 50.625vw;_x000D_
  /* ratio = 9/16 * 90 = 50.625 */_x000D_
  background: pink;_x000D_
  max-height: 90vh;_x000D_
  max-width: 160vh;_x000D_
  /* 16/9 * 90 = 160 */_x000D_
  margin: auto;_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  bottom: 0;_x000D_
  left: 0;_x000D_
  right: 0;_x000D_

Also, browser support is pretty good too: IE9+, FF, Chrome, Safari- caniuse

How to fix Uncaught InvalidValueError: setPosition: not a LatLng or LatLngLiteral: in property lat: not a number?

you can use this way

 map = new google.maps.Map(document.getElementById('map'), {
        zoom: 16,
        center: { lat: parseFloat(lat), lng: parseFloat(lng) },
        mapTypeId: 'terrain', 
        disableDefaultUI: true

EX : center: { lat: parseFloat(lat), lng: parseFloat(lng) },

How do I vertically center an H1 in a div?


<div id='sample'>
<span class='vertical'>Test Message</span>


        text-align: center;


Fiddle : Demo

vertical-align with Bootstrap 3

I just did this and it does what I want it to do.

.align-middle {
  margin-top: 25%;
  margin-bottom: 25%;

And now my page looks like

<div class='container-fluid align-middle'>

 |                                |
 |  +--------------------------+  |
 |  |                          |  |
 |  |                          |  |
 |  |                          |  |
 |  |                          |  |
 |  |                          |  |
 |  +--------------------------+  |
 |                                |

<select> HTML element with height

You can also "center" the text with:

vertical-align: middle;

Vertical align middle with Bootstrap responsive grid

Add !important rule to display: table of your .v-center class.

.v-center {
    display:table !important;
    border:2px solid gray;

Your display property is being overridden by bootstrap to display: block.


How to set an button align-right with Bootstrap?

<div class="container">
    <div class="btn-block pull-right">
        <a href="#" class="btn btn-primary pull-right">Search</a>
        <a href="#" class="btn btn-primary pull-right">Apple</a>
        <a href="#" class="btn btn-primary pull-right">Sony</a>

Grid of responsive squares

The accepted answer is great, however this can be done with flexbox.

Here's a grid system written with BEM syntax that allows for 1-10 columns to be displayed per row.

If there the last row is incomplete (for example you choose to show 5 cells per row and there are 7 items), the trailing items will be centered horizontally. To control the horizontal alignment of the trailing items, simply change the justify-content property under the .square-grid class.

.square-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;

.square-grid__cell {
  background-color: rgba(0, 0, 0, 0.03);
  box-shadow: 0 0 0 1px black;
  overflow: hidden;
  position: relative;

.square-grid__content {
  left: 0;
  position: absolute;
  top: 0;

.square-grid__cell:after {
  content: '';
  display: block;
  padding-bottom: 100%;

// Sizes – Number of cells per row

.square-grid__cell--10 {
  flex-basis: 10%;

.square-grid__cell--9 {
  flex-basis: 11.1111111%;

.square-grid__cell--8 {
  flex-basis: 12.5%;

.square-grid__cell--7 {
  flex-basis: 14.2857143%;

.square-grid__cell--6 {
  flex-basis: 16.6666667%;

.square-grid__cell--5 {
  flex-basis: 20%;

.square-grid__cell--4 {
  flex-basis: 25%;

.square-grid__cell--3 {
  flex-basis: 33.333%;

.square-grid__cell--2 {
  flex-basis: 50%;

.square-grid__cell--1 {
  flex-basis: 100%;

.square-grid {_x000D_
  display: flex;_x000D_
  flex-wrap: wrap;_x000D_
  justify-content: center;_x000D_
.square-grid__cell {_x000D_
  background-color: rgba(0, 0, 0, 0.03);_x000D_
  box-shadow: 0 0 0 1px black;_x000D_
  overflow: hidden;_x000D_
  position: relative;_x000D_
.square-grid__content {_x000D_
  left: 0;_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
.square-grid__cell:after {_x000D_
  content: '';_x000D_
  display: block;_x000D_
  padding-bottom: 100%;_x000D_
// Sizes – Number of cells per row_x000D_
.square-grid__cell--10 {_x000D_
  flex-basis: 10%;_x000D_
.square-grid__cell--9 {_x000D_
  flex-basis: 11.1111111%;_x000D_
.square-grid__cell--8 {_x000D_
  flex-basis: 12.5%;_x000D_
.square-grid__cell--7 {_x000D_
  flex-basis: 14.2857143%;_x000D_
.square-grid__cell--6 {_x000D_
  flex-basis: 16.6666667%;_x000D_
.square-grid__cell--5 {_x000D_
  flex-basis: 20%;_x000D_
.square-grid__cell--4 {_x000D_
  flex-basis: 25%;_x000D_
.square-grid__cell--3 {_x000D_
  flex-basis: 33.333%;_x000D_
.square-grid__cell--2 {_x000D_
  flex-basis: 50%;_x000D_
.square-grid__cell--1 {_x000D_
  flex-basis: 100%;_x000D_
<div class='square-grid'>_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_
  <div class='square-grid__cell square-grid__cell--7'>_x000D_
    <div class='square-grid__content'>_x000D_
      Some content_x000D_


This is tested in FF and Chrome.

How to set dropdown arrow in spinner?

Set the Dropdown arrow image to spinner like this :


Here android:background="@drawable/spinner_bg" the spinner_bg is the Dropdown arrow image.

Adjust plot title (main) position

We can use title() function with negative line value to bring down the title.

See this example:

plot(1, 1)
title("Title", line = -2)

enter image description here

Android Layout Animations from bottom to top and top to bottom on ImageView click

Below Kotlin code will help

Bottom to Top or Slide to Up

private fun slideUp() {
    isMapInfoShown = true
    val animate = TranslateAnimation(
        0f,  // fromXDelta
        0f,  // toXDelta
        views!!.layoutMapInfo.height.toFloat(),  // fromYDelta
        0f  // toYDelta

    animate.duration = 500
    animate.fillAfter = true

Top to Bottom or Slide to Down

private fun slideDown() {
    if (isMapInfoShown) {
        isMapInfoShown = false
        val animate = TranslateAnimation(
            0f,  // fromXDelta
            0f,  // toXDelta
            0f,  // fromYDelta
            views!!.layoutMapInfo.height.toFloat()  // toYDelta

        animate.duration = 500
        animate.fillAfter = true

Kotlin Extensions for Visible and Gone

fun View.visible() {
    this.visibility = View.VISIBLE

fun View.gone() {
    this.visibility = View.GONE

Submit button not working in Bootstrap form

Your problem is this

<button type="button" value=" Send" class="btn btn-success" type="submit" id="submit" />

You've set the type twice. Your browser is only accepting the first, which is "button".

<button type="submit" value=" Send" class="btn btn-success" id="submit" />

How to align linearlayout to vertical center?

You can change set orientation of linearlayout programmatically by:

LinearLayout linearLayout =new linearLayout(this);//just to give the clarity

android.content.res.Resources$NotFoundException: String resource ID #0x0





There are different versions of setText - one takes a String and one takes an int resource id. If you pass it an integer it will try to look for the corresponding string resource id - which it can't find, which is your error.

I guess app.getTotalDl() returns an int. You need to specifically tell setText to set it to the String value of this int.

setText (int resid) vs setText (CharSequence text)

How can I use onItemSelected in Android?

I think this will benefit you Try this I'm using to change the language in my application

String[] districts;
Spinner sp;


 sp = (Spinner) findViewById(;
         districts = getResources().getStringArray(R.array.lang_array);
         ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item,districts);
         sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long arg3) {
                  // TODO Auto-generated method stub
                  int index = arg0.getSelectedItemPosition();
                  Toast.makeText(getBaseContext(), "You select "+districts[index]+" id "+position, Toast.LENGTH_LONG).show();
                      case 0:
                      case 1:
                      case 2:
                      default: //For all other cases, do this
            public void onNothingSelected(AdapterView<?> arg0) {
                   // TODO Auto-generated method stub

and this is my String Array

<string-array name="lang_array">

Twitter Bootstrap 3, vertically center content

You can use display:inline-block instead of float and vertical-align:middle with this CSS:

.col-lg-4, .col-lg-8 {

The demo

How can I parse a local JSON file from assets folder into a ListView?

As Faizan describes in their answer here:

First of all read the Json File from your assests file using below code.

and then you can simply read this string return by this function as

public String loadJSONFromAsset() {
    String json = null;
    try {
        InputStream is = getActivity().getAssets().open("yourfilename.json");
        int size = is.available();
        byte[] buffer = new byte[size];;
        json = new String(buffer, "UTF-8");
    } catch (IOException ex) {
        return null;
    return json;

and use this method like that

    try {
        JSONObject obj = new JSONObject(loadJSONFromAsset());
        JSONArray m_jArry = obj.getJSONArray("formules");
        ArrayList<HashMap<String, String>> formList = new ArrayList<HashMap<String, String>>();
        HashMap<String, String> m_li;

        for (int i = 0; i < m_jArry.length(); i++) {
            JSONObject jo_inside = m_jArry.getJSONObject(i);
            Log.d("Details-->", jo_inside.getString("formule"));
            String formula_value = jo_inside.getString("formule");
            String url_value = jo_inside.getString("url");

            //Add your values in your `ArrayList` as below:
            m_li = new HashMap<String, String>();
            m_li.put("formule", formula_value);
            m_li.put("url", url_value);

    } catch (JSONException e) {

For further details regarding JSON Read HERE

Bootstrap 3 : Vertically Center Navigation Links when Logo Increasing The Height of Navbar

I found that you don't necessarily need the text vertically centred, it also looks good near the bottom of the row, it's only when it's at the top (or above centre?) that it looks wrong. So I went with this to push the links to the bottom of the row:

.navbar-brand {
    min-height: 80px;

@media (min-width: 768px) {
    #navbar-collapse {
        position: absolute;
        bottom: 0px;
        left: 250px;

My brand image is SVG and I used height: 50px; width: auto which makes it about 216px wide. It spilled out of its container vertically so I added the min-height: 80px; to make room for it plus bootstrap's 15px margins. Then I tweaked the navbar-collapse's left setting until it looked right.

Custom height Bootstrap's navbar

You need also to set .min-height: 0px; please see bellow:

.navbar-inner {
    min-height: 0px;

.navbar-nav li a {
    line-height: 150px;
    height: 150px;
    padding-top: 0;

If you set .min-height: 0px; then you can choose any height you want!

Good Luck!

Bootstrap 3 scrollable div for table

A scrolling comes from a box with class pre-scrollable

<div class="pre-scrollable"></div>

There's more examples:
Wish it helps.

Implement Validation for WPF TextBoxes

To get it done only with XAML you need to add Validation Rules for individual properties. But i would recommend you to go with code behind approach. In your code, define your specifications in properties setters and throw exceptions when ever it doesn't compliance to your specifications. And use error template to display your errors to user in UI. Your XAML will look like this

<Window x:Class="WpfApplication1.MainWindow"
    Title="MainWindow" Height="350" Width="525">
    <Style x:Key="CustomTextBoxTextStyle" TargetType="TextBox">
        <Setter Property="Foreground" Value="Green" />
        <Setter Property="MaxLength" Value="40" />
        <Setter Property="Width" Value="392" />
            <Trigger Property="Validation.HasError" Value="True">
                    <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self},Path=(Validation.Errors)[0].ErrorContent}"/>
                    <Setter Property="Background" Value="Red"/>
    <TextBox Name="tb2" Height="30" Width="400"
             Text="{Binding Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnExceptions=True}" 
             Style="{StaticResource CustomTextBoxTextStyle}"/>

Code Behind:

public partial class MainWindow : Window
    private ExampleViewModel m_ViewModel;
    public MainWindow()
        m_ViewModel = new ExampleViewModel();
        DataContext = m_ViewModel;

public class ExampleViewModel : INotifyPropertyChanged
    private string m_Name = "Type Here";
    public ExampleViewModel()


    public string Name
            return m_Name;
            if (String.IsNullOrEmpty(value))
                throw new Exception("Name can not be empty.");
            if (value.Length > 12)
                throw new Exception("name can not be longer than 12 charectors");
            if (m_Name != value)
                m_Name = value;

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName)
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));


Add Items to ListView - Android

Try this one it will work

public class Third extends ListActivity {
private ArrayAdapter<String> adapter;
private List<String> liste;
protected void onCreate(Bundle savedInstanceState) {
     String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
                "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
                "Linux", "OS/2" };
     liste = new ArrayList<String>();
     Collections.addAll(liste, values);
     adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, liste);
  protected void onListItemClick(ListView l, View v, int position, long id) {

How to center an element horizontally and vertically

This is a related problem that people might come to this page when searching: When I want to centre a div for a (100px square) "waiting.." animated gif I use :

  .centreDiv {
        position: absolute;
        top: calc(50vh - 50px);
        top: -moz-calc(50vh - 50px);
        top: -webkit-calc(50vh - 50px);
        left: calc(50vw - 50px);
        left: -moz-calc(50vw - 50px);
        left: -webkit-calc(50vw - 50px);
        z-index: 1000; /*whatever is required*/

How to make all controls resize accordingly proportionally when window is maximized?

Well, it's fairly simple to do.

On the window resize event handler, calculate how much the window has grown/shrunk, and use that fraction to adjust 1) Height, 2) Width, 3) Canvas.Top, 4) Canvas.Left properties of all the child controls inside the canvas.

Here's the code:

private void window1_SizeChanged(object sender, SizeChangedEventArgs e)
            myCanvas.Width = e.NewSize.Width;
            myCanvas.Height = e.NewSize.Height;

            double xChange = 1, yChange = 1;

            if (e.PreviousSize.Width != 0)
            xChange = (e.NewSize.Width/e.PreviousSize.Width);

            if (e.PreviousSize.Height != 0)
            yChange = (e.NewSize.Height / e.PreviousSize.Height);

            foreach (FrameworkElement fe in myCanvas.Children )
                /*because I didn't want to resize the grid I'm having inside the canvas in this particular instance. (doing that from xaml) */            
                if (fe is Grid == false)
                    fe.Height = fe.ActualHeight * yChange;
                    fe.Width = fe.ActualWidth * xChange;

                    Canvas.SetTop(fe, Canvas.GetTop(fe) * yChange);
                    Canvas.SetLeft(fe, Canvas.GetLeft(fe) * xChange);


Flexbox Not Centering Vertically in IE

The original answer from



HTTP Status 500 - org.apache.jasper.JasperException: java.lang.NullPointerException

NullPointerException with JSP can also happen if:

A getter returns a non-public inner class.

This code will fail if you remove Getters's access modifier or make it private or protected.


package com.myPackage;
public class MyClass{ 
    //: Must be public or you will get:
    //: org.apache.jasper.JasperException: 
    //: java.lang.NullPointerException
    public class Getters{
        public String 
        myProperty(){ return(my_property); }

    //: JSP EL can only access functions:
    private Getters _get;
    public  Getters  get(){ return _get; }

    private String 

    public MyClass(String my_property){
        this.my_property    = my_property;
        _get = new Getters();


<%@ taglib uri   ="" prefix="c" %>
<%@ page import="com.myPackage.MyClass" %>
    MyClass inst = new MyClass("[PROP_VALUE]");
    pageContext.setAttribute("my_inst", inst ); 
%><html lang="en"><body>
    ${ my_inst.get().myProperty() }

Horizontal scroll css?

Just make sure you add box-sizing:border-box; to your #myWorkContent.

How do I set vertical space between list items?

You can use margin. See the example:

  margin: 10px 0;

Body set to overflow-y:hidden but page is still scrollable in Chrome

Ok so this is the combination that worked for me when I had this problem on one of my websites:

html {
    height: 100%;

body {
    overflow-x: hidden;

Vertical divider doesn't work in Bootstrap 3

I find using the pipe character with some top and bottom padding works well. Using a div with a border will require more CSS to vertically align it and get the horizontal spacing even with the other elements.


.divider-vertical {
    padding-top: 14px;
    padding-bottom: 14px;


<ul class="nav navbar-nav">
    <li class="active"><a href="#">Home</a></li>
    <li class="divider-vertical">&#124;</li>
    <li><a href="#">Faq</a></li>
    <li class="divider-vertical">&#124;</li>
    <li><a href="#">News</a></li>
    <li class="divider-vertical">&#124;</li>
    <li><a href="#">Contact</a></li>

Center align with table-cell

This would be easier to do with flexbox. Using flexbox will let you not to specify the height of your content and can adjust automatically on the height it contains.


here's the gist of the demo


  display: flex;
  height: 100%;
  justify-content: center;
  align-items: center;



<div class="container">
  <div class='content'> //you can size this anyway you want
    put anything you want here,

enter image description here

Adding custom radio buttons in android

I realize this is a belated answer, but looking through, it seems that the Toggle button would be ideal for your situation.

Toggle button image

And of course you can still use the other suggestions for having a background drawable to get a custom look you want.


Now if you want to go with your final edit and have a "halo" effect around your buttons, you can use another custom selector to do just that.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:state_selected="true" > <!-- selected -->
                android:color="@android:color/white" />
                android:color="@android:color/holo_blue_bright" />
                android:radius="5dp" />
    <item> <!-- default -->
                android:color="@android:color/white" />
                android:color="@android:color/darker_gray" />
                android:radius="5dp" />

Center icon in a div - horizontally and vertically

Here is a way to center content both vertically and horizontally in any situation, which is useful when you do not know the width or height or both:


#container {
    display: table;
    width: 300px; /* not required, just for example */
    height: 400px; /* not required, just for example */

#update {
    display: table-cell;
    vertical-align: middle;
    text-align: center;


<div id="container">
    <a id="update" href="#">
        <i class="icon-refresh"></i>


Note that the width and height values are just for demonstration here, you can change them to anything you want (or remove them entirely) and it will still work because the vertical centering here is a product of the way the table-cell display property works.

Android draw a Horizontal line between views

Creating it once and using it wherever needed is a good idea. Add this in your styles.xml:

<style name="Divider">
    <item name="android:layout_width">match_parent</item>
    <item name="android:layout_height">1dp</item>
    <item name="android:background">?android:attr/listDivider</item>

and add this in your xml code, where a line divider is needed:

<View style="@style/Divider"/>

Originally answered by toddles_fp to this question: Android Drawing Separator/Divider Line in Layout?

Placing a textview on top of imageview in android

you can try this too. I use just framelayout.


                    android:text="Hello !"
                    android:layout_gravity="left|bottom" />

Bootstrap 3 Gutter Size

Add these helper classes to the stylesheet.less (you can use to compile them to CSS )

.row.gutter-0 {
    margin-left: 0;
    margin-right: 0;
    [class*="col-"] {
        padding-left: 0;
        padding-right: 0;

.row.gutter-10 {
    margin-left: -5px;
    margin-right: -5px;
    [class*="col-"] {
        padding-left: 5px;
        padding-right: 5px;

.row.gutter-20 {
    margin-left: -10px;
    margin-right: -10px;
    [class*="col-"] {
        padding-left: 10px;
        padding-right: 10px;

And here’s how you can use it in your HTML:

<div class="row gutter-0">
    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">


<div class="row gutter-10">
    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">


<div class="row gutter-20">
    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">

    <div class="col-sm-3 col-md-3 col-lg-3">


Flexbox: center horizontally and vertically

diplay: flex; for it's container and margin:auto; for it's item works perfect.

NOTE: You have to setup the width and height to see the effect.

  width: 100%; /*width needs to be setup*/_x000D_
  height: 150px; /*height needs to be setup*/_x000D_
  display: flex;_x000D_
  margin: auto; /*These will make the item in center*/_x000D_
  background-color: #CCC;_x000D_
<div id="container">_x000D_
   <div class="item">CENTER</div>_x000D_

Android translate animation - permanently move View to new position using AnimationListener

I usually prefer to work with deltas in translate animation, since it avoids a lot of confusion.

Try this out, see if it works for you:

TranslateAnimation anim = new TranslateAnimation(0, amountToMoveRight, 0, amountToMoveDown);

anim.setAnimationListener(new TranslateAnimation.AnimationListener() {

    public void onAnimationStart(Animation animation) { }

    public void onAnimationRepeat(Animation animation) { }

    public void onAnimationEnd(Animation animation) 
        FrameLayout.LayoutParams params = (FrameLayout.LayoutParams)view.getLayoutParams();
        params.topMargin += amountToMoveDown;
        params.leftMargin += amountToMoveRight;


Make sure to make amountToMoveRight / amountToMoveDown final

Hope this helps :)

Button Listener for button in fragment in android

While you are declaring onclick in XML then you must declair method and pass View v as parameter and make the method public...

//in xml

// in java file
public void onButtonClicked(View v)
//your code here

How to center and crop an image to always appear in square shape with CSS?

<div style="specify your dimension:overflow:hidden">
    <div style="margin-top:-50px">
       <img ...  />

The above will crop 50px from the top of the image. You may want to compute to come up wit a top margin that will fit your requirements based on the dimension of the image.

To crop from the bottom simply specify the height of the outer div and remove the inner div. Apply the same principle to crop from the sides.

A div with auto resize when changing window width\height

Use vh attributes. It means viewport height and is a percentage. So height: 90vh would mean 90% of the viewport height. This works in most modern browsers.


div {
  height: 90vh;

You can forego the rest of your silly 100% stuff on the body.

If you have a header you can also do some fun things like take it into account by using the calc function in CSS.


div {
  height: calc(100vh - 50px);

This will give you 100% of the viewport height, minus 50px for your header.

vertical align middle in <div>

 div {_x000D_
    text-align: center;_x000D_
    padding: 2px;_x000D_
    border: 1px solid #000;_x000D_
    background-color: green;_x000D_
.text-align-center {_x000D_
    display: flex;_x000D_
    align-items: center;_x000D_
    justify-content: center;_x000D_
<div class="text-align-center"> Align center</div>

Decreasing height of bootstrap 3.0 navbar

if you are using the less source, there should be a variable for the navbar height in the variables.less file. If you are not using the source, then you can customize it using the customize utilty that bootstrap's site provides. And then you can downloaded it and include it in your project. The variable you are looking for is: @navbar-height

Prevent scroll-bar from adding-up to the Width of page on Chrome

I found I could add

::-webkit-scrollbar { 
display: none; 

directly to my css and it would make the scrollbar invisible, but still allow me to scroll (on Chrome at least). Good for when you don't want a distracting scrollbar on your page!

How to vertically align label and input in Bootstrap 3?

None of these solutions worked for me. But I was able to get vertical centering by using <div class="form-row align-items-center"> for each form row, per the Bootstrap examples.

Vertically align an image inside a div with responsive height

Try this one

          vertical-align: middle;

Android findViewById() in Custom View

If it's fixed layout you can do like that:

public void onClick(View v) {
   ViewGroup parent = (ViewGroup) IdNumber.this.getParent();
   EditText firstName = (EditText) parent.findViewById(;
   firstName.setText("Some Text");

If you want find the EditText in flexible layout, I will help you later. Hope this help.

Responsive Image full screen and centered - maintain aspect ratio, not exceed window

You could use a div with a background image instead and this CSS3 property:

background-size: contain

You can check out an example on:

To quote Mozilla:

The contain value specifies that regardless of the size of the containing box, the background image should be scaled so that each side is as large as possible while not exceeding the length of the corresponding side of the container.

However, keep in mind that your image will be upscaled if the div is larger than your original image.

Stacked Tabs in Bootstrap 3

The Bootstrap team seems to have removed it. See here: . @Skelly's answer involves custom css which I didn't want to do so I used the grid system and nav-pills. It worked fine and looked great. The code looks like so:

<div class="row">

  <!-- Navigation Buttons -->
  <div class="col-md-3">
    <ul class="nav nav-pills nav-stacked" id="myTabs">
      <li class="active"><a href="#home" data-toggle="pill">Home</a></li>
      <li><a href="#profile" data-toggle="pill">Profile</a></li>
      <li><a href="#messages" data-toggle="pill">Messages</a></li>

  <!-- Content -->
  <div class="col-md-9">
    <div class="tab-content">
      <div class="tab-pane active" id="home">Home</div>
      <div class="tab-pane" id="profile">Profile</div>
      <div class="tab-pane" id="messages">Messages</div>


You can see this in action here:

[Update] @SeanK gives the option of not having to enable the nav-pills through Javascript and instead using data-toggle="pill". Check it out here: Thanks Sean.

Bootstrap 3 modal vertical position center

In mobile plantform it might look a little different, here's my code.

<div class="modal-container">
    margin-top: 60%;
    margin-left: 10%;
    margin-right: 10%;
    margin-bottom: 100%
  @media screen and (orientation:landscape){
      margin-top: 70;
      margin-left: 10%;
      margin-right: 10%;
      margin-bottom: 100%
    text-align: center;
  .modal-body p{
    margin:14px 0px;
    font-size: 110%;
    border-radius: 10px;
  .modal-footer a{
    padding: 15px;
  .modal-footer a:nth-child(1){
    border-radius: 0px 0px 0px 10px;
  .modal-footer a:nth-child(2){
    border-radius: 0px 0px 10px 0px;
  <h2>Basic Modal Example</h2>
  <div data-toggle="modal" data-target="#myModal">Div for modal</div>
    <div class="modal fade" id="myModal" role="dialog">
      <div class="modal-dialog">
        <div class="modal-content">
          <div class="modal-body">
          <div class="modal-footer">
            <div class="btn-group btn-group-justified">
              <a href="#" class="btn btn-default" data-dismiss="modal">??</a>
              <a href="#" class="btn btn-default" data-dismiss="modal">??</a>

OnItemClickListener using ArrayAdapter for ListView

Ok, after the information that your Activity extends ListActivity here's a way to implement OnItemClickListener:

public class newListView extends ListView {

    public newListView(Context context) {

    public void setOnItemClickListener(
            android.widget.AdapterView.OnItemClickListener listener) {
        //do something when item is clicked



Android list view inside a scroll view

Don't do anything in Parent ScrollView. Only do this to child ListView. Everything will work perfectly.

mListView.setOnTouchListener(new View.OnTouchListener() {
            public boolean onTouch(View v, MotionEvent event) {
               int action = event.getActionMasked();
                switch (action) {
                    case MotionEvent.ACTION_UP:
                return false;

SSIS - Text was truncated or one or more characters had no match in the target code page - Special Characters

If you go to the Flat file connection manager under Advanced and Look at the "OutputColumnWidth" description's ToolTip It will tell you that Composit characters may use more spaces. So the "é" in "Société" most likely occupies more than one character.

EDIT: Here's something about it:

Show Error on the tip of the Edit Text Android

private void showError() {
   mEditText.setError("Password and username didn't match");

Which will result in errors shown like this:

enter image description here

And if you want to remove it:


Adding Table rows Dynamically in Android

You also can, as Fredigato said, declare a RelativeLayout in a separate Layout file. Then instantiate it using:

for(int i = 0; i < 6; i ++){
LayoutInflater inflater = (LayoutInflater)getApplicationContext().getSystemService
RelativeLayout row = (RelativeLayout) inflater.inflate(R.layout.table_view,null);

In this approach you can easily design one custom row using XML and reuse it.

Now, to be able to change the children views in the instantiated RelativeLayout. You can call row.childAt(index).

So lets say you have a TextView in the RelativeLayout, you can use:

TextView tv = (TextView) row.childAt(0);

How to use vertical align in bootstrap

For the parent: display: table;

For the child: display: table-cell;

Then add vertical-align: middle;

I can make a fiddle but home time now, yay!

OK here is the lovely fiddle:

.parent {

.child {

How can I add a vertical scrollbar to my div automatically?

Since OS X Lion, the scrollbar on websites are hidden by default and only visible once you start scrolling. Personally, I prefer the hidden scrollbar, but in case you really need it, you can overwrite the default and force the scrollbar in WebKit browsers back like this:

::-webkit-scrollbar {
    -webkit-appearance: none;
    width: 7px;
::-webkit-scrollbar-thumb {
    border-radius: 4px;
    background-color: rgba(0,0,0,.5);
    -webkit-box-shadow: 0 0 1px rgba(255,255,255,.5);

Android getting value from selected radiobutton

int genid=gender.getCheckedRadioButtonId();
RadioButton radioButton = (RadioButton) findViewById(genid);
String gender=radioButton.getText().toString();

Hope this works. You can convert your output to string in the above manner. gender.getCheckedRadioButtonId(); - gender is the id of RadioGroup.

Scale Image to fill ImageView width and keep aspect ratio

I did something similar to the above and then banged my head against the wall for a few hours because it did not work inside a RelativeLayout. I ended up with the following code:

package com.example;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;

public class ScaledImageView extends ImageView {
    public ScaledImageView(final Context context, final AttributeSet attrs) {
        super(context, attrs);

    protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) {
        final Drawable d = getDrawable();

        if (d != null) {
            int width;
            int height;
            if (MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.EXACTLY) {
                height = MeasureSpec.getSize(heightMeasureSpec);
                width = (int) Math.ceil(height * (float) d.getIntrinsicWidth() / d.getIntrinsicHeight());
            } else {
                width = MeasureSpec.getSize(widthMeasureSpec);
                height = (int) Math.ceil(width * (float) d.getIntrinsicHeight() / d.getIntrinsicWidth());
            setMeasuredDimension(width, height);
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);

And then to prevent RelativeLayout from ignoring the measured dimension I did this:



Column order manipulation using col-lg-push and col-lg-pull in Twitter Bootstrap 3

I just felt like I'll add my $0.2 to those 2 good answers. I had a case when I had to move the last column all the way to the top in a 3-column situation.






Boostrap's class .col-xx-push-Xdoes nothing else but pushes a column to the right with left: XX%; so all you have to do to push a column right is to add the number of pseudo columns going left.

In this case:

  • two columns (col-md-5 and col-md-3) are going left, each with the value of the one that is going right;

  • one(col-md-4) is going right by the sum of the first two going left (5+3=8);

<div class="row">
    <div class="col-md-4 col-md-push-8 ">
    <div class="col-md-5 col-md-pull-4">
    <div class="col-md-3 col-md-pull-4">

enter image description here

Vertically centering Bootstrap modal window

you can use:

.modal {
    position: fixed;
    top: 50% !important;
    left: 50%;
    transform: translate(-50%, -50%);

to center it both vertically and horizontally.

How to center the content inside a linear layout?

Here's some sample code. This worked for me.


So you're designing the Linear Layout to place all its contents (TextView and Button) in its center, and then the TextView and Button are placed relative to the center of the Linear Layout.

draw diagonal lines in div background with CSS

If you'd like the cross to be partially transparent, the naive approach would be to make linear-gradient colors semi-transparent. But that doesn't work out good due to the alpha blending at the intersection, producing a differently colored diamond. The solution to this is to leave the colors solid but add transparency to the gradient container instead:

.cross {_x000D_
  position: relative;_x000D_
.cross::after {_x000D_
  pointer-events: none;_x000D_
  content: "";_x000D_
  position: absolute;_x000D_
  top: 0; bottom: 0; left: 0; right: 0;_x000D_
.cross1::after {_x000D_
    linear-gradient(to top left, transparent 45%, rgba(255,0,0,0.35) 46%, rgba(255,0,0,0.35) 54%, transparent 55%),_x000D_
    linear-gradient(to top right, transparent 45%, rgba(255,0,0,0.35) 46%, rgba(255,0,0,0.35) 54%, transparent 55%);_x000D_
.cross2::after {_x000D_
    linear-gradient(to top left, transparent 45%, rgb(255,0,0) 46%, rgb(255,0,0) 54%, transparent 55%),_x000D_
    linear-gradient(to top right, transparent 45%, rgb(255,0,0) 46%, rgb(255,0,0) 54%, transparent 55%);_x000D_
  opacity: 0.35;_x000D_
div { width: 180px; text-align: justify; display: inline-block; margin: 20px; }
<div class="cross cross1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam et dui imperdiet, dapibus augue quis, molestie libero. Cras nisi leo, sollicitudin nec eros vel, finibus laoreet nulla. Ut sit amet leo dui. Praesent rutrum rhoncus mauris ac ornare. Donec in accumsan turpis, pharetra eleifend lorem. Ut vitae aliquet mi, id cursus purus.</div>_x000D_
<div class="cross cross2">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam et dui imperdiet, dapibus augue quis, molestie libero. Cras nisi leo, sollicitudin nec eros vel, finibus laoreet nulla. Ut sit amet leo dui. Praesent rutrum rhoncus mauris ac ornare. Donec in accumsan turpis, pharetra eleifend lorem. Ut vitae aliquet mi, id cursus purus.</div>

How to remove padding around buttons in Android?

After hours of digging around multiple answers I finally found a solution that doesn't use a different element, manipulate minHeight or minWidth, or even wrapping Button around a RelativeLayout.

    android:background="@color/whatever" />

The main takeaway here is the setting of the foreground instead of background as many of the answers stipulate. Changing the background itself to selectableItemBackground will just overwrite any changes you made to the button's color/background, if any.

Changing the foreground gives you the best of both worlds: get rid of the "invisible" padding and retain your button's design.

DynamoDB vs MongoDB NoSQL

With 500k documents, there is no reason to scale whatsoever. A typical laptop with an SSD and 8GB of ram can easily do 10s of millions of records, so if you are trying to pick because of scaling your choice doesn't really matter. I would suggest you pick what you like the most, and perhaps where you can find the most online support with.

HTML Form Redirect After Submit

Try this Javascript (jquery) code. Its an ajax request to an external URL. Use the callback function to fire any code:

<script type="text/javascript">
$(function() {
    $.post('', function() {
      window.location = '';
    return false;

get parent's view from a layout

Just write


Vertically aligning text next to a radio button

_x000D_ {vertical-align:middle; margin-top:8px; margin-bottom:12px;}

SIMPLY Adjust top and bottom as needed for PERFECT ALIGNMENT of radio button or checkbox

<input type="radio" class="radio">

Why is width: 100% not working on div {display: table-cell}?

Just add min-height:100% and min-width:100% and it will work. I had the same problem. You don't need a 3th wrapper

CSS getting text in one line rather than two

Add white-space: nowrap;:

.garage-title {
    clear: both;
    display: inline-block;
    overflow: hidden;
    white-space: nowrap;


Warning: mysqli_error() expects exactly 1 parameter, 0 given error

mysqli_error() needs you to pass the connection to the database as a parameter. Documentation here has some helpful examples:

Try altering your problem line like so and you should be in good shape:

$query = mysqli_query($myConnection, $sqlCommand) or die (mysqli_error($myConnection)); 

How to make a HTTP request using Ruby on Rails?

You can use Ruby's Net::HTTP class:

require 'net/http'

url = URI.parse('')
req =
res = Net::HTTP.start(, url.port) {|http|
puts res.body

How to deploy a Java Web Application (.war) on tomcat?

The tomcat manual says:

Copy the web application archive file into directory $CATALINA_HOME/webapps/. When Tomcat is started, it will automatically expand the web application archive file into its unpacked form, and execute the application that way.

How do I open multiple instances of Visual Studio Code?

Easiest when you don't know the CTRL+SHIFT+N shortcut is to use the menu: File, New Window

enter image description here

How to analyse the heap dump using jmap in java

Very late to answer this, but worth to take a quick look at. Just 2 minutes needed to understand in detail.

First create this java program

import java.util.ArrayList;
import java.util.List;

public class GarbageCollectionAnalysisExample{
    public static void main(String[] args) {
           List<String> l = new ArrayList<String>();
           for (int i = 0; i < 100000000; i++) {
                  l = new ArrayList<String>(); //Memory leak

Use jps to find the vmid (virtual machine id i.e. JVM id)

Go to CMD and type below commands >

18588 Jps
17252 GarbageCollectionAnalysisExample
2084 Main

17252 is the vmid which we need.

Now we will learn how to use jmap and jhat

Use jmap - to generate heap dump

From java docs about jmap “jmap prints shared object memory maps or heap memory details of a given process or core file or a remote debug server”

Use following command to generate heap dump >

C:\>jmap -dump:file=E:\heapDump.jmap 17252
Dumping heap to E:\heapDump.jmap ...
Heap dump file created

Where 17252 is the vmid (picked from above).

Heap dump will be generated in E:\heapDump.jmap

Now use Jhat Jhat is used for analyzing the garbage collection dump in java -

C:\>jhat E:\heapDump.jmap
Reading from E:\heapDump.jmap...
Dump file created Mon Nov 07 23:59:19 IST 2016
Snapshot read, resolving...
Resolving 241865 objects...
Chasing references, expect 48 dots................................................
Eliminating duplicate references................................................
Snapshot resolved.
Started HTTP server on port 7000
Server is ready.

By default, it will start http server on port 7000. Then we will go to http://localhost:7000/

Courtesy : JMAP, How to monitor and analyze the garbage collection in 10 ways

Waiting for background processes to finish before exiting script

GNU parallel and xargs

These two tools that can make scripts simpler, and also control the maximum number of threads (thread pool). E.g.:

seq 10 | xargs -P4 -I'{}' echo '{}'


seq 10 | parallel -j4  echo '{}'

See also: how to write a process-pool bash shell

How to find out if a Python object is a string?

Python 3

In Python 3.x basestring is not available anymore, as str is the sole string type (with the semantics of Python 2.x's unicode).

So the check in Python 3.x is just:

isinstance(obj_to_test, str)

This follows the fix of the official 2to3 conversion tool: converting basestring to str.

Laravel - Pass more than one variable to view

Please try this,

$ms = Person::where('name', 'Foo Bar')->first();
$persons = Person::order_by('list_order', 'ASC')->get();
return View::make('viewname')->with(compact('persons','ms'));

Python error when trying to access list by index - "List indices must be integers, not str"

player['score'] is your problem. player is apparently a list which means that there is no 'score' element. Instead you would do something like:

name, score = player[0], player[1]
return name + ' ' + str(score)

Of course, you would have to know the list indices (those are the 0 and 1 in my example).

Something like player['score'] is allowed in python, but player would have to be a dict.

You can read more about both lists and dicts in the python documentation.

Centering the pagination in bootstrap

Using laravel with bootstrap 4, the solution that worked:

<div class="d-flex">
    <div class="mx-auto">

How to initialize a struct in accordance with C programming language standards

void function(void) {
  MY_TYPE a;
  a.flag = true;
  a.value = 15;
  a.stuff = 0.123;

How to replicate vector in c?

You can see implementation vc_vector:

struct vc_vector {
  size_t count;
  size_t element_size;
  size_t reserved_size;
  char* data;
  vc_vector_deleter* deleter;


vc_vector* vc_vector_create_copy(const vc_vector* vector) {
  vc_vector* new_vector = vc_vector_create(vector->reserved_size / vector->count,
  if (unlikely(!new_vector)) {
    return new_vector;

  if (memcpy(vector->data,
             new_vector->element_size * vector->count) == NULL) {
    new_vector = NULL;
    return new_vector;

  new_vector->count = vector->count;
  return new_vector;

To use it:

vc_vector* v1 = vc_vector_create(0, sizeof(int), NULL);
for (int i = 0; i < 10; ++i) {
  vc_vector_push_back(v1, &i);

// v1 = 0 1 2 3 4 5 6 7 8 9

vc_vector* v2 = vc_vector_create_copy(v1);

// v2 = 0 1 2 3 4 5 6 7 8 9 (copy of v1)

// to get pointer to int:

const int* v2_data = vc_vector_data(v1);

How to force Docker for a clean build of an image

In some extreme cases, your only way around recurring build failures is by running:

docker system prune

The command will ask you for your confirmation:

WARNING! This will remove:
    - all stopped containers
    - all volumes not used by at least one container
    - all networks not used by at least one container
    - all images without at least one container associated to them
Are you sure you want to continue? [y/N]

This is of course not a direct answer to the question, but might save some lives... It did save mine.

Setting UILabel text to bold

Use attributed string:

// Define attributes
let labelFont = UIFont(name: "HelveticaNeue-Bold", size: 18)
let attributes :Dictionary = [NSFontAttributeName : labelFont]

// Create attributed string
var attrString = NSAttributedString(string: "Foo", attributes:attributes)
label.attributedText = attrString

You need to define attributes.

Using attributed string you can mix colors, sizes, fonts etc within one text

filedialog, tkinter and opening files

Did you try adding the self prefix to the fileName and replacing the method above the Button ? With the self, it becomes visible between methods.


def load_file(self):
    self.fileName = filedialog.askopenfilename(filetypes = (("Template files", "*.tplate")
                                                     ,("HTML files", "*.html;*.htm")
                                                     ,("All files", "*.*") ))

Assign multiple values to array in C

If you are doing these same assignments a lot in your program and want a shortcut, the most straightforward solution might be to just add a function

static inline void set_coordinates(
        GLfloat coordinates[static 8],
        GLfloat c0, GLfloat c1, GLfloat c2, GLfloat c3,
        GLfloat c4, GLfloat c5, GLfloat c6, GLfloat c7)
    coordinates[0] = c0;
    coordinates[1] = c1;
    coordinates[2] = c2;
    coordinates[3] = c3;
    coordinates[4] = c4;
    coordinates[5] = c5;
    coordinates[6] = c6;
    coordinates[7] = c7;

and then simply call

GLfloat coordinates[8];
// ...
set_coordinates(coordinates, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f);

Maximum concurrent Socket.IO connections

I tried to use on AWS, I can at most keep around 600 connections stable.

And I found out it is because used long polling first and upgraded to websocket later.

after I set the config to use websocket only, I can keep around 9000 connections.

Set this config at client side:

const socket = require('')
const conn = socket(host, { upgrade: false, transports: ['websocket'] })

Add data to JSONObject

In order to have this result:


that holds the same data as:

    "aoColumnDefs": [
     { "aDataSort": [ 0, 1 ], "aTargets": [ 0 ] },
     { "aDataSort": [ 1, 0 ], "aTargets": [ 1 ] },
     { "aDataSort": [ 2, 3, 4 ], "aTargets": [ 2 ] }

you could use this code:

    JSONObject jo = new JSONObject();
    Collection<JSONObject> items = new ArrayList<JSONObject>();

    JSONObject item1 = new JSONObject();
    item1.put("aDataSort", new JSONArray(0, 1));
    item1.put("aTargets", new JSONArray(0));
    JSONObject item2 = new JSONObject();
    item2.put("aDataSort", new JSONArray(1, 0));
    item2.put("aTargets", new JSONArray(1));
    JSONObject item3 = new JSONObject();
    item3.put("aDataSort", new JSONArray(2, 3, 4));
    item3.put("aTargets", new JSONArray(2));

    jo.put("aoColumnDefs", new JSONArray(items));


Checking session if empty or not

Use this if the session variable emp_num will store a string:

 if (!string.IsNullOrEmpty(Session["emp_num"] as string))
                //The code

If it doesn't store a string, but some other type, you should just check for null before accessing the value, as in your second example.

How to check if the request is an AJAX request with PHP

This function is using in yii framework for ajax call check.

public function isAjax() {
        return isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] === 'XMLHttpRequest';

How do I specify new lines on Python, when writing on files?

The new line character is \n. It is used inside a string.


    print('First line \n Second line') 

where \n is the newline character.

This would yield the result:

First line
 Second line

If you use Python 2, you do not use the parentheses on the print function.

How to change PHP version used by composer

If anyone is still having trouble, remember you can run composer with any php version that you have installed e.g. $ php7.3 -f /usr/local/bin/composer update

Use which composer command to help locate the composer executable.

What is external linkage and internal linkage?

Before talking about the question, it is better to know the term translation unit, program and some basic concepts of C++ (actually linkage is one of them in general) precisely. You will also have to know what is a scope.

I will emphasize some key points, esp. those missing in previous answers.

Linkage is a property of a name, which is introduced by a declaration. Different names can denote same entity (typically, an object or a function). So talking about linkage of an entity is usually nonsense, unless you are sure that the entity will only be referred by the unique name from some specific declarations (usually one declaration, though).

Note an object is an entity, but a variable is not. While talking about the linkage of a variable, actually the name of the denoted entity (which is introduced by a specific declaration) is concerned. The linkage of the name is in one of the three: no linkage, internal linkage or external linkage.

Different translation units can share the same declaration by header/source file (yes, it is the standard's wording) inclusion. So you may refer the same name in different translation units. If the name declared has external linkage, the identity of the entity referred by the name is also shared. If the name declared has internal linkage, the same name in different translation units denotes different entities, but you can refer the entity in different scopes of the same translation unit. If the name has no linkage, you simply cannot refer the entity from other scopes.

(Oops... I found what I have typed was somewhat just repeating the standard wording ...)

There are also some other confusing points which are not covered by the language specification.

  1. Visibility (of a name). It is also a property of declared name, but with a meaning different to linkage.
  2. Visibility (of a side effect). This is not related to this topic.
  3. Visibility (of a symbol). This notion can be used by actual implementations. In such implementations, a symbol with specific visibility in object (binary) code is usually the target mapped from the entity definition whose names having the same specific linkage in the source (C++) code. However, it is usually not guaranteed one-to-one. For example, a symbol in a dynamic library image can be specified only shared in that image internally from source code (involved with some extensions, typically, __attribute__ or __declspec) or compiler options, and the image is not the whole program or the object file translated from a translation unit, thus no standard concept can describe it accurately. Since symbol is not a normative term in C++, it is only an implementation detail, even though the related extensions of dialects may have been widely adopted.
  4. Accessibility. In C++, this is usually about property of class members or base classes, which is again a different concept unrelated to the topic.
  5. Global. In C++, "global" refers something of global namespace or global namespace scope. The latter is roughly equivalent to file scope in the C language. Both in C and C++, the linkage has nothing to do with scope, although scope (like linkage) is also tightly concerned with an identifier (in C) or a name (in C++) introduced by some declaration.

The linkage rule of namespace scope const variable is something special (and particularly different to the const object declared in file scope in C language which also has the concept of linkage of identifiers). Since ODR is enforced by C++, it is important to keep no more than one definition of the same variable or function occurred in the whole program except for inline functions. If there is no such special rule of const, a simplest declaration of const variable with initializers (e.g. = xxx) in a header or a source file (often a "header file") included by multiple translation units (or included by one translation unit more than once, though rarely) in a program will violate ODR, which makes to use const variable as replacement of some object-like macros impossible.

Delaying function in swift

For adding argument to delay function.

First setup a dictionary then add it as the userInfo. Unwrap the info with the timer as the argument.

let arg : Int = 42
let infoDict : [String : AnyObject] = ["argumentInt", arg]

NSTimer.scheduledTimerWithTimeInterval(NSTimeInterval(3), target: self, selector: "functionHereWithArgument:", userInfo: infoDict, repeats: false)

Then in the called function

func functionHereWithArgument (timer : NSTimer)
    if let userInfo = timer.userInfo as? Dictionary<String, AnyObject>
         let argumentInt : Int = (userInfo[argumentInt] as! Int)

How can I convert a .jar to an .exe?

If your program is "publicly available non-commercial in nature" and has "a publicly available Web site that meets the basic quality standards", then you can try and get a free license of Excelsior. If its not then it's expensive, but still a viable option.


As a side note: Here's a study of all existing Jar to EXE programs, which is a bit depressing -

Difference between PCDATA and CDATA in DTD

From here (Google is your friend):

In a DTD, PCDATA and CDATA are used to assert something about the allowable content of elements and attributes, respectively. In an element's content model, #PCDATA says that the element contains (may contain) "any old text." (With exceptions as noted below.) In an attribute's declaration, CDATA is one sort of constraint you can put on the attribute's allowable values (other sorts, all mutually exclusive, include ID, IDREF, and NMTOKEN). An attribute whose allowable values are CDATA can (like PCDATA in an element) contain "any old text."

A potentially really confusing issue is that there's another "CDATA," also referred to as marked sections. A marked section is a portion of element (#PCDATA) content delimited with special strings: to close it. If you remember that PCDATA is "parsed character data," a CDATA section is literally the same thing, without the "parsed." Parsers transmit the content of a marked section to downstream applications without hiccupping every time they encounter special characters like < and &. This is useful when you're coding a document that contains lots of those special characters (like scripts and code fragments); it's easier on data entry, and easier on reading, than the corresponding entity reference.

So you can infer that the exception to the "any old text" rule is that PCDATA cannot include any of these unescaped special characters, UNLESS they fall within the scope of a CDATA marked section.

"Fatal error: Unable to find local grunt." when running "grunt" command

I think you have to add grunt to your package.json file. See this link.

How to force table cell <td> content to wrap?

Just add: word-break: break-word; to you table class.

Difference between long and int data types

From this reference:

An int was originally intended to be the "natural" word size of the processor. Many modern processors can handle different word sizes with equal ease.

Also, this bit:

On many (but not all) C and C++ implementations, a long is larger than an int. Today's most popular desktop platforms, such as Windows and Linux, run primarily on 32 bit processors and most compilers for these platforms use a 32 bit int which has the same size and representation as a long.

AJAX POST and Plus Sign ( + ) -- How to Encode?

To make it more interesting and to hopefully enable less hair pulling for someone else. Using python, built dictionary for a device which we can use curl to configure.

Problem: {"timezone":"+5"} //throws an error " 5"

Solution: {"timezone":"%2B"+"5"} //Works

So, in a nutshell:

var = {"timezone":"%2B"+"5"}
json = JSONEncoder().encode(var)["curl",ipaddress,"-XPUT","-d","data="+json])

Thanks to this post!

Available text color classes in Bootstrap

You can use text classes:


use text classes in any tag where needed.

<p class="text-primary">.text-primary</p>
<p class="text-secondary">.text-secondary</p>
<p class="text-success">.text-success</p>
<p class="text-danger">.text-danger</p>
<p class="text-warning">.text-warning</p>
<p class="text-info">.text-info</p>
<p class="text-light bg-dark">.text-light</p>
<p class="text-dark">.text-dark</p>
<p class="text-muted">.text-muted</p>
<p class="text-white bg-dark">.text-white</p>

You can add your own classes or modify above classes as your requirement.

Open JQuery Datepicker by clicking on an image w/ no input field

<img src='someimage.gif' id="datepicker" />
<input type="hidden" id="dp" />

 $(document).on("click", "#datepicker", function () {
    dateFormat: 'dd-mm-yy',
    minDate: 'today'}).datepicker( "show" ); 

you just add this code for image clicking or any other html tag clicking event. This is done by initiate the datepicker function when we click the trigger.

How to play video with AVPlayerViewController (AVKit) in Swift

Swift 3.0 Full source code:

import UIKit
    import AVKit
    import AVFoundation

    class ViewController: UIViewController,AVPlayerViewControllerDelegate
        var playerController = AVPlayerViewController()

        @IBAction func Play(_ sender: Any)
            let path = Bundle.main.path(forResource: "video", ofType: "mp4")

            let url = NSURL(fileURLWithPath: path!)

            let player = AVPlayer(url:url as URL)

            playerController = AVPlayerViewController()

            NotificationCenter.default.addObserver(self, selector: #selector(ViewController.didfinishplaying(note:)),name:NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem)

            playerController.player = player

            playerController.allowsPictureInPicturePlayback = true

            playerController.delegate = self



        func didfinishplaying(note : NSNotification)
            playerController.dismiss(animated: true,completion: nil)
            let alertview = UIAlertController(title:"finished",message:"video finished",preferredStyle: .alert)
            alertview.addAction(UIAlertAction(title:"Ok",style: .default, handler: nil))
            self.present(alertview,animated:true,completion: nil)

        func playerViewController(_ playerViewController: AVPlayerViewController, restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void) {
                let currentviewController =  navigationController?.visibleViewController

                if currentviewController != playerViewController
                    currentviewController?.present(playerViewController,animated: true,completion:nil)


How to parse a JSON string to an array using Jackson

I sorted this problem by verifying the json on and then using Jackson. Below is the code for the same.

 Main Class:-

String jsonStr = "[{\r\n" + "       \"name\": \"John\",\r\n" + "        \"city\": \"Berlin\",\r\n"
                + "         \"cars\": [\r\n" + "            \"FIAT\",\r\n" + "          \"Toyata\"\r\n"
                + "     ],\r\n" + "     \"job\": \"Teacher\"\r\n" + "   },\r\n" + " {\r\n"
                + "     \"name\": \"Mark\",\r\n" + "        \"city\": \"Oslo\",\r\n" + "        \"cars\": [\r\n"
                + "         \"VW\",\r\n" + "            \"Toyata\"\r\n" + "     ],\r\n"
                + "     \"job\": \"Doctor\"\r\n" + "    }\r\n" + "]";

        ObjectMapper mapper = new ObjectMapper();

        MyPojo jsonObj[] = mapper.readValue(jsonStr, MyPojo[].class);

        for (MyPojo itr : jsonObj) {

            System.out.println("Val of getName is: " + itr.getName());
            System.out.println("Val of getCity is: " + itr.getCity());
            System.out.println("Val of getJob is: " + itr.getJob());
            System.out.println("Val of getCars is: " + itr.getCars() + "\n");



public class MyPojo {

private List<String> cars = new ArrayList<String>();

private String name;

private String job;

private String city;

public List<String> getCars() {
    return cars;

public void setCars(List<String> cars) { = cars;

public String getName() {
    return name;

public void setName(String name) { = name;

public String getJob() {
    return job;

public void setJob(String job) {
    this.job = job;

public String getCity() {
    return city;

public void setCity(String city) { = city;
} }

         Val of getName is: John
         Val of getCity is: Berlin
         Val of getJob is: Teacher
         Val of getCars is: [FIAT, Toyata]

          Val of getName is: Mark
          Val of getCity is: Oslo
          Val of getJob is: Doctor
          Val of getCars is: [VW, Toyata]

Extract XML Value in bash script

XMLStarlet or another XPath engine is the correct tool for this job.

For instance, with data.xml containing the following:

    <title>15:54:57 - George:</title>
    <description>Diane DeConn? You saw Diane DeConn!</description> 
    <title>15:55:17 - Jerry:</title> 
    <description>Something huh?</description>
</root> can extract only the first title with the following:

xmlstarlet sel -t -m '//title[1]' -v . -n <data.xml

Trying to use sed for this job is troublesome. For instance, the regex-based approaches won't work if the title has attributes; won't handle CDATA sections; won't correctly recognize namespace mappings; can't determine whether a portion of the XML documented is commented out; won't unescape attribute references (such as changing Brewster &amp; Jobs to Brewster & Jobs), and so forth.

How to go up a level in the src path of a URL in HTML?

Here is all you need to know about relative file paths:

  • Starting with / returns to the root directory and starts there

  • Starting with ../ moves one directory backward and starts there

  • Starting with ../../ moves two directories backward and starts there (and so on...)

  • To move forward, just start with the first sub directory and keep moving forward.

Click here for more details!

How can I detect when an Android application is running in the emulator?

try this link from github.

This module help you to emulator detection to your Android project suported Unity.

Basic checker

  • BlueStacks
  • Genymotion
  • Android Emulator
  • Nox App Player
  • Koplayer
  • .....

Firebase FCM notifications click_action payload

there is dual method for fcm fcm messaging notification and app notification in first your app reciever only message notification with body ,title and you can add color ,vibration not working,sound default. in 2nd you can full control what happen when you recieve message example onMessageReciever(RemoteMessage rMessage){ notification.setContentTitle(rMessage.getData().get("yourKey")); } you will recieve data with(yourKey) but that not from fcm message that from fcm cloud functions reguard

Best HTTP Authorization header type for JWT

Short answer

The Bearer authentication scheme is what you are looking for.

Long answer

Is it related to bears?

Errr... No :)

According to the Oxford Dictionaries, here's the definition of bearer:

bearer /'b??r?/

  1. A person or thing that carries or holds something.

  2. A person who presents a cheque or other order to pay money.

The first definition includes the following synonyms: messenger, agent, conveyor, emissary, carrier, provider.

And here's the definition of bearer token according to the RFC 6750:

1.2. Terminology

Bearer Token

A security token with the property that any party in possession of the token (a "bearer") can use the token in any way that any other party in possession of it can. Using a bearer token does not require a bearer to prove possession of cryptographic key material (proof-of-possession).

The Bearer authentication scheme is registered in IANA and originally defined in the RFC 6750 for the OAuth 2.0 authorization framework, but nothing stops you from using the Bearer scheme for access tokens in applications that don't use OAuth 2.0.

Stick to the standards as much as you can and don't create your own authentication schemes.

An access token must be sent in the Authorization request header using the Bearer authentication scheme:

2.1. Authorization Request Header Field

When sending the access token in the Authorization request header field defined by HTTP/1.1, the client uses the Bearer authentication scheme to transmit the access token.

For example:

GET /resource HTTP/1.1
Authorization: Bearer mF_9.B5f-4.1JqM


Clients SHOULD make authenticated requests with a bearer token using the Authorization request header field with the Bearer HTTP authorization scheme. [...]

In case of invalid or missing token, the Bearer scheme should be included in the WWW-Authenticate response header:

3. The WWW-Authenticate Response Header Field

If the protected resource request does not include authentication credentials or does not contain an access token that enables access to the protected resource, the resource server MUST include the HTTP WWW-Authenticate response header field [...].

All challenges defined by this specification MUST use the auth-scheme value Bearer. This scheme MUST be followed by one or more auth-param values. [...].

For example, in response to a protected resource request without authentication:

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example"

And in response to a protected resource request with an authentication attempt using an expired access token:

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example",
                         error_description="The access token expired"

How to store command results in a shell variable?

The syntax to store the command output into a variable is var=$(command).

So you can directly do:

result=$(ls -l | grep -c "rahul.*patle")

And the variable $result will contain the number of matches.

How to find the privileges and roles granted to a user in Oracle?

select * 
where role in (
    select granted_role
    from dba_role_privs 
    where granted_role in ('ROLE1','ROLE2')

How can I debug my JavaScript code?

I use old good printf approach (an ancient technique which will work well in any time).

Look to magic %o:

console.log("this is %o, event is %o, host is %s", this, e,;

%o dump clickable and deep-browsable, pretty-printed content of JS object. %s was shown just for a record.

And this:

console.log("%s", new Error().stack);

gives you Java-like stack trace to point of new Error() invocation (including path to file and line number!!).

Both %o and new Error().stack available in Chrome and Firefox.

With such powerful tools you make assumption whats going wrong in your JS, put debug output (don't forget wrap in if statement to reduce amount of data) and verify your assumption. Fix issue or make new assumption or put more debug output to bit problem.

Also for stack traces use:


as say Console

Happy hacking!

How to get first N elements of a list in C#?

var firstFiveItems = myList.Take(5);

Or to slice:

var secondFiveItems = myList.Skip(5).Take(5);

And of course often it's convenient to get the first five items according to some kind of order:

var firstFiveArrivals = myList.OrderBy(i => i.ArrivalTime).Take(5);

Dynamic creation of table with DOM

<title>Registration Form</title>
    var table;

    function check() {
        var name =;
        if (name == "" || name == null) {
            document.getElementById("span1").innerHTML = "Please enter the Name";
            document.getElementById("name").style.border = "2px solid red";
            return false;
        else {
            document.getElementById("span1").innerHTML = "";
            document.getElementById("name").style.border = "2px solid green";

        var age = document.myForm.age.value;
        var ageFormat = /^(([1][8-9])|([2-5][0-9])|(6[0]))$/gm;

        if (age == "" || age == null) {
            document.getElementById("span2").innerHTML = "Please provide Age";
            document.getElementById("age").style.border = "2px solid red";
            return false;
        else if (!ageFormat.test(age)) {
            document.getElementById("span2").innerHTML = "Age can't be leass than 18 and greater than 60";
            document.getElementById("age").style.border = "2px solid red";
            return false;
        else {
            document.getElementById("span2").innerHTML = "";
            document.getElementById("age").style.border = "2px solid green";

        var password = document.myForm.password.value;
        if (document.myForm.password.length < 6) {
            alert("Error: Password must contain at least six characters!");
            document.getElementById("password").style.border = "2px solid red";
            return false;
        re = /[0-9]/g;
        if (!re.test(password)) {
            alert("Error: password must contain at least one number (0-9)!");
            document.getElementById("password").style.border = "2px solid red";
            return false;
        re = /[a-z]/g;
        if (!re.test(password)) {
            alert("Error: password must contain at least one lowercase letter (a-z)!");
            document.getElementById("password").style.border = "2px solid red";
            return false;
        re = /[A-Z]/g;
        if (!re.test(password)) {
            alert("Error: password must contain at least one uppercase letter (A-Z)!");
            document.getElementById("password").style.border = "2px solid red";
            return false;
        re = /[$&+,:;=?@#|'<>.^*()%!-]/g;
        if (!re.test(password)) {
            alert("Error: password must contain at least one special character!");
            document.getElementById("password").style.border = "2px solid red";
            return false;
        else {
            document.getElementById("span3").innerHTML = "";
            document.getElementById("password").style.border = "2px solid green";


        if (document.getElementById("data") == null)
        else {
        return true;

    function createTable() {

        var myTableDiv = document.getElementById("myTable");  //indiv
        table = document.createElement("TABLE");   //TABLE??
        table.setAttribute("id", "data");
        table.border = '1';
        myTableDiv.appendChild(table);  //appendChild() insert it in the document (table --> myTableDiv)

        var header = table.createTHead();

        var th0 = table.tHead.appendChild(document.createElement("th"));
        th0.innerHTML = "Name";
        var th1 = table.tHead.appendChild(document.createElement("th"));
        th1.innerHTML = "Age";



    function appendRow() {
        var name =;
        var age = document.myForm.age.value;

        var rowCount = table.rows.length;
        var row = table.insertRow(rowCount);

        row.insertCell(0).innerHTML = name;
        row.insertCell(1).innerHTML = age;



    function clearForm() {
        debugger; = "";
        document.myForm.password.value = "";
        document.myForm.age.value = "";

    function restrictCharacters(evt) {

        evt = (evt) ? evt : window.event;
        var charCode = (evt.which) ? evt.which : evt.keyCode;
        if (((charCode >= '65') && (charCode <= '90')) || ((charCode >= '97') && (charCode <= '122')) || (charCode == '32')) {
            return true;
        else {
            return false;


    <form name="myForm">

        <table id="tableid">

                    <input type="text" name="name" placeholder="Name" id="name" onkeypress="return restrictCharacters(event);" /></td>
                <td><span id="span1"></span></td>


                    <input type="text" onkeypress="return event.charCode === 0 || /\d/.test(String.fromCharCode(event.charCode));" placeholder="Age"
                        name="age" id="age" /></td>
                <td><span id="span2"></span></td>

                    <input type="password" name="password" id="password" placeholder="Password" /></td>
                <td><span id="span3"></span></td>

                    <input type="button" value="Submit" onclick="check();" /></td>
                    <input type="reset" name="Reset" /></td>


    <div id="myTable">


HTML page disable copy/paste

You cannot prevent people from copying text from your page. If you are trying to satisfy a "requirement" this may work for you:

<body oncopy="return false" oncut="return false" onpaste="return false">

How to disable Ctrl C/V using javascript for both internet explorer and firefox browsers

A more advanced aproach:

How to detect Ctrl+V, Ctrl+C using JavaScript?

Edit: I just want to emphasise that disabling copy/paste is annoying, won't prevent copying and is 99% likely a bad idea.

How do I specify local .gem files in my Gemfile?

This isn't strictly an answer to your question about installing .gem packages, but you can specify all kinds of locations on a gem-by-gem basis by editing your Gemfile.

Specifying a :path attribute will install the gem from that path on your local machine.

gem "foreman", path: "/Users/pje/my_foreman_fork"

Alternately, specifying a :git attribute will install the gem from a remote git repository.

gem "foreman", git: "git://"

# ...or at a specific SHA-1 ref
gem "foreman", git: "git://", ref: "bf648a070c"

# ...or branch
gem "foreman", git: "git://", branch: "jruby"

# ...or tag
gem "foreman", git: "git://", tag: "v0.45.0"

(As @JHurrah mentioned in his comment.)

Building a fat jar using maven

Maybe you want maven-shade-plugin, bundle dependencies, minimize unused code and hide external dependencies to avoid conflicts.



How to reset settings in Visual Studio Code?

If you want to start afresh, deleting the settings.json file from your user's profile will do the trick.

But if you don't want to reset everything, it is still possible through settings menu.

settings menu

You can search for the setting that you want to revert back using search box.

You will see some settings with the left blue line, it means you've modified that one.

search setting

If you take your cursor to that setting, a gear button will appear. You can click this to restore that setting.

gear button

You can also use the drop-down below that setting and change it to default.

setting drop down

Is there a timeout for idle PostgreSQL connections?

It sounds like you have a connection leak in your application because it fails to close pooled connections. You aren't having issues just with <idle> in transaction sessions, but with too many connections overall.

Killing connections is not the right answer for that, but it's an OK-ish temporary workaround.

Rather than re-starting PostgreSQL to boot all other connections off a PostgreSQL database, see: How do I detach all other users from a postgres database? and How to drop a PostgreSQL database if there are active connections to it? . The latter shows a better query.

For setting timeouts, as @Doon suggested see How to close idle connections in PostgreSQL automatically?, which advises you to use PgBouncer to proxy for PostgreSQL and manage idle connections. This is a very good idea if you have a buggy application that leaks connections anyway; I very strongly recommend configuring PgBouncer.

A TCP keepalive won't do the job here, because the app is still connected and alive, it just shouldn't be.

In PostgreSQL 9.2 and above, you can use the new state_change timestamp column and the state field of pg_stat_activity to implement an idle connection reaper. Have a cron job run something like this:

SELECT pg_terminate_backend(pid)
    FROM pg_stat_activity
    WHERE datname = 'regress'
      AND pid <> pg_backend_pid()
      AND state = 'idle'
      AND state_change < current_timestamp - INTERVAL '5' MINUTE;

In older versions you need to implement complicated schemes that keep track of when the connection went idle. Do not bother; just use pgbouncer.

How to create standard Borderless buttons (like in the design guideline mentioned)?

From the iosched app source I came up with this ButtonBar class:

 * An extremely simple {@link LinearLayout} descendant that simply reverses the 
 * order of its child views on Android 4.0+. The reason for this is that on 
 * Android 4.0+, negative buttons should be shown to the left of positive buttons.
public class ButtonBar extends LinearLayout {

    public ButtonBar(Context context) {

    public ButtonBar(Context context, AttributeSet attributes) {
        super(context, attributes);

    public ButtonBar(Context context, AttributeSet attributes, int def_style) {
        super(context, attributes, def_style);

    public View getChildAt(int index) {
        if (_has_ics)
            // Flip the buttons so that "OK | Cancel" becomes "Cancel | OK" on ICS
            return super.getChildAt(getChildCount() - 1 - index);

        return super.getChildAt(index);

    private final static boolean _has_ics = Build.VERSION.SDK_INT >= 

This will be the LinearLayout that the "OK" and "Cancel" buttons go into, and will handle putting them in the appropriate order. Then put this in the layout you want the buttons in:

<LinearLayout xmlns:android=""
    <!--- A view, this approach only works with a single view here -->
    <your.package.ButtonBar style="?android:attr/buttonBarStyle"
        <Button style="?android:attr/buttonBarButtonStyle"
            android:text="@string/ok_button" />
        <Button style="?android:attr/buttonBarButtonStyle"
            android:text="@string/cancel_button" />

This gives you the look of the dialog with borderless buttons. You can find these attributes in the res in the framework. buttonBarStyle does the vertical divider and padding. buttonBarButtonStyle is set as borderlessButtonStyle for Holo theme, but I believe this should be the most robust way for displaying it as the framework wants to display it.

Return HTML content as a string, given URL. Javascript Function

Here's a version of the accepted answer that 1) returns a value from the function (bugfix), and 2) doesn't break when using "use strict";

I use this code to pre-load a .txt file into my <textarea> when the user loads the page.

function httpGet(theUrl)
    let xmlhttp;
    if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
    } else { // code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttp.onreadystatechange=function() {
        if (xmlhttp.readyState==4 && xmlhttp.status==200) {
            return xmlhttp.responseText;
    }"GET", theUrl, false);
    return xmlhttp.response;

How do you use Intent.FLAG_ACTIVITY_CLEAR_TOP to clear the Activity Stack?

Though this question already has sufficient answers, I thought somebody would want to know why this flag works in this peculiar manner, This is what I found in Android documentation

The currently running instance of activity B in the above example will either receive the new intent you are starting here in its onNewIntent() method, or be itself finished and restarted with the new intent.

If it has declared its launch mode to be "multiple" (the default) and you have not set FLAG_ACTIVITY_SINGLE_TOP in the same intent, then it will be finished and re-created; for all other launch modes or if FLAG_ACTIVITY_SINGLE_TOP is set then this Intent will be delivered to the current instance's onNewIntent().

So, Either,
1. Change the launchMode of the Activity A to something else from standard (ie. singleTask or something). Then your flag FLAG_ACTIVITY_CLEAR_TOP will not restart your Activity A.


2. Use Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP as your flag. Then it will work the way you desire.

xcode-select active developer directory error

There are only two steps required, and the full is not required at all:

sudo rm -rf /Library/Developer/CommandLineTools
xcode-select --install

At this point the "Installing Softwre" dialog pops up:

enter image description here

That's it!

How do I clear a search box with an 'x' in bootstrap 3?

Do it with inline styles and script:

<div class="btn-group has-feedback has-clear">
    <input id="searchinput" type="search" class="form-control" style="width:200px;">
class="glyphicon glyphicon-remove-circle form-control-feedback form-control-clear" 
style="pointer-events:auto; text-decoration:none; cursor:pointer;"
onclick="$(this).prev('input').val('');return false;">

How do I check if a C++ string is an int?

Since C++11 you can make use of std::all_of and ::isdigit:

#include <algorithm>
#include <cctype>
#include <iostream>
#include <string_view>

int main([[maybe_unused]] int argc, [[maybe_unused]] char *argv[])
    auto isInt = [](std::string_view str) -> bool {
        return std::all_of(str.cbegin(), str.cend(), ::isdigit);

    for(auto &test : {"abc", "123abc", "123.0", "+123", "-123", "123"}) {
        std::cout << "Is '" << test << "' numeric? " 
            << (isInt(test) ? "true" : "false") << std::endl;

    return 0;

Check out the result with Godbolt.

How do I use HTML as the view engine in Express?

HTML files can be rendered using ejs engine:

app.set('view engine', 'ejs');

And make sure your files under "/views" are named with ".ejs".

For example "index.ejs".

How to enable cross-origin resource sharing (CORS) in the express.js framework on node.js

Try to this cors npm modules.

var cors = require('cors')

var app = express()

This module provides many features to fine tune cors setting such as domain whitelisting, enabling cors for specific apis etc.

Simplest way to serve static data from outside the application server in a Java web application

This is story from my workplace:
- We try to upload multiply images and document files use Struts 1 and Tomcat 7.x.
- We try to write uploaded files to file system, filename and full path to database records.
- We try to separate file folders outside web app directory. (*)

The below solution is pretty simple, effective for requirement (*):

In file META-INF/context.xml file with the following content: (Example, my application run at http://localhost:8080/ABC, my application / project named ABC). (this is also full content of file context.xml)

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/ABC" aliases="/images=D:\images,/docs=D:\docs"/>

(works with Tomcat version 7 or later)

Result: We have been created 2 alias. For example, we save images at: D:\images\foo.jpg and view from link or using image tag:

<img src="http://localhost:8080/ABC/images/foo.jsp" alt="Foo" height="142" width="142">


<img src="/images/foo.jsp" alt="Foo" height="142" width="142">

(I use Netbeans 7.x, Netbeans seem auto create file WEB-INF\context.xml)

key_load_public: invalid format

I had the same warning. It was a very old key. I regenerated a key on the current OpenSSH 7, and the error was gone.

Android Left to Right slide animation

Use this xml in res/anim/

This is for left to right animation:

<set xmlns:android=""
  <translate android:fromXDelta="-100%" android:toXDelta="0%"
             android:fromYDelta="0%" android:toYDelta="0%"

This is for right to left animation:

<set xmlns:android=""
     android:fromXDelta="0%" android:toXDelta="100%"
     android:fromYDelta="0%" android:toYDelta="0%"
     android:duration="700" />

In your coding use intent like for left to right:


In your coding use intent like for right to left


How to convert Java String to JSON Object

Your json -

    "title":"Free Music Archive - Genres",

Using the JSON library from -

JSONObject o = new JSONObject(jsonString);


The following information will be helpful to you -


import org.json.JSONObject;
 //Other lines of code
URL seatURL = new URL("
 //Return the JSON Response from the API
 BufferedReader br = new BufferedReader(new         
 String readAPIResponse = " ";
 StringBuilder jsonString = new StringBuilder();
 while((readAPIResponse = br.readLine()) != null){
 JSONObject jsonObj = new JSONObject(jsonString.toString());

What can be the reasons of connection refused errors?

In Ubuntu, Try sudo ufw allow <port_number> to allow firewall access to both of your server and db.

Select parent element of known element in Selenium

There are a couple of options there. The sample code is in Java, but a port to other languages should be straightforward.


WebElement myElement = driver.findElement("myDiv"));
WebElement parent = (WebElement) ((JavascriptExecutor) driver).executeScript(
                                   "return arguments[0].parentNode;", myElement);


WebElement myElement = driver.findElement("myDiv"));
WebElement parent = myElement.findElement(By.xpath("./.."));

Obtaining the driver from the WebElement

Note: As you can see, for the JavaScript version you'll need the driver. If you don't have direct access to it, you can retrieve it from the WebElement using:

WebDriver driver = ((WrapsDriver) myElement).getWrappedDriver();

Resizing an iframe based on content

This is an old thread, but in 2020 it's still a relevant question. I've actually posted this answer in another old thread as well^^ (

Just wanted to share my solution and excitement. It took me four entire days of intensive research and failure, but I think I've found a neat way of making iframes entirely responsive! Yey!

I tried a ton of different approaches... I didn't want to use a two-way communication tunnel as with postMessage because it's awkward for same-origin and complicated for cross-origin (as no admin wants to open doors and implement this on your behalf).

I've tried using MutationObservers and still needed several EventListeners (resize, click,..) to ensure that every change of the layout was handled correctly. - What if a script toggles the visibility of an element? Or what if it dynamically preloads more content on demand? - Another issue was getting an accurate height of the iframe contents from somewhere. Most people suggest using scrollHeight or offsetHeight, or combination of it by using Math.max. The problem is, that these values don't get updated until the iframe element changes its dimensions. To achieve that you could simply reset the iframe.height = 0 before grabbing the scrollHeight, but there are even more caveats to this. So, screw this.

Then, I had another idea to experiment with requestAnimationFrame to get rid of my events and observers hell. Now, I could react to every layout change immediately, but I still had no reliable source to infer the content height of the iframe from. And theeen I discovered getComputedStyle, by accident! This was an enlightenment! Everything just clicked.

Well, see the code I could eventually distill from my countless attempts.

function fit() {
    var iframes = document.querySelectorAll("")

    for(var id = 0; id < iframes.length; id++) {
        var win = iframes[id].contentWindow
        var doc = win.document
        var html = doc.documentElement
        var body = doc.body
        var ifrm = iframes[id] // or win.frameElement

        if(body) {
   = "scroll" // scrollbar-jitter fix
   = "hidden"
        if(html) {
   = "scroll" // scrollbar-jitter fix
   = "hidden"
            var style = win.getComputedStyle(html)
            ifrm.width = parseInt(style.getPropertyValue("width")) // round value
            ifrm.height = parseInt(style.getPropertyValue("height"))


addEventListener("load", requestAnimationFrame.bind(this, fit))

That is it, yes! - In your HTML code write <iframe src="page.html" class="gh-fit gh-fullwidth"></iframe>. The gh-fit is a just fake CSS class, used to identify which iframe elements in your DOM should be affect by the script. The gh-fullwidth is a simple CSS class with one rule width: 100%;.

The above script automatically fetches all iframes from the DOM, that have a .gh-fit class assigned. It then grabs and uses the pre-calculated style values for width and height from document.getComputedStyle(iframe), which always contain a pixel-perfect size of that element!!! Just perfect!

Note, this solution doesn't work cross-origin (nor does any other solution, without a two-way communication strategy like IFrameResizer). JS simply can't access the DOM of an iframe, if it doesn't belong to you.

The only other cross-origin solution I can think of, is to use a proxy like But this would involve deep-copying every request you make - in other words - you 'steal' the entire page source code (to make it yours and let JS access the DOM) and you patch every link/path in this source, so that it goes through the proxy as well. The re-linking routine is a tough one, but doable.

I'll probably try myself at this cross-origin problem, but that's for another day. Enjoy the code! :)

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required?

I have the same problem.

I have found this solution:

Google may block sign in attempts from some apps or devices that do not use modern security standards. Since these apps and devices are easier to break into, blocking them helps keep your account safer.

Some examples of apps that do not support the latest security standards include:

  • The Mail app on your iPhone or iPad with iOS 6 or below
  • The Mail app on your Windows phone preceding the 8.1 release
  • Some Desktop mail clients like Microsoft Outlook and Mozilla Thunderbird

Therefore, you have to enable Less Secure Sign-In (or Less secure app access) in your google account.

After sign into google account, go to:

In C#, you can use the following code:

using (MailMessage mail = new MailMessage())
    mail.From = new MailAddress("[email protected]");
    mail.To.Add("[email protected]");
    mail.Subject = "Hello World";
    mail.Body = "<h1>Hello</h1>";
    mail.IsBodyHtml = true;
    mail.Attachments.Add(new Attachment("C:\\"));

    using (SmtpClient smtp = new SmtpClient("", 587))
        smtp.Credentials = new NetworkCredential("[email protected]", "password");
        smtp.EnableSsl = true;

Info shared by Michael Freidgeim in below comments area:
Similar answer with screenshots

parsing JSONP $http.jsonp() response in angular.js

UPDATE: since Angular 1.6

You can no longer use the JSON_CALLBACK string as a placeholder for specifying where the callback parameter value should go

You must now define the callback like so:

$http.jsonp('some/trusted/url', {jsonpCallbackParam: 'callback'})

Change/access/declare param via $http.defaults.jsonpCallbackParam, defaults to callback

Note: You must also make sure your URL is added to the trusted/whitelist:


or explicitly trusted via:


success/error were deprecated.

The $http legacy promise methods success and error have been deprecated and will be removed in v1.6.0. Use the standard then method instead. If $httpProvider.useLegacyPromiseExtensions is set to false then these methods will throw $http/legacy error.


var url = ""
var trustedUrl = $sce.trustAsResourceUrl(url);

$http.jsonp(trustedUrl, {jsonpCallbackParam: 'callback'})

Previous Answer: Angular 1.5.x and before

All you should have to do is change callback=jsonp_callback to callback=JSON_CALLBACK like so:

var url = "";

And then your .success function should fire like you have it if the return was successful.

Doing it this way keeps you from having to dirty up the global space. This is documented in the AngularJS documentation here.

Updated Matt Ball's fiddle to use this method:

Full example:

var url = "";


Redirect on Ajax Jquery Call

For ExpressJs router:'/login', async(req, res) => {
    return res.send({redirect: '/yoururl'});


    success: function (response) {
        if (response.redirect) {
            window.location = response.redirect

Getting the array length of a 2D array in Java

import java.util.Arrays;

public class Main {

    public static void main(String[] args) 

        double[][] test = { {100}, {200}, {300}, {400}, {500}, {600}, {700}, {800}, {900}, {1000}};

        int [][] removeRow = { {0}, {1}, {3}, {4}, };

        double[][] newTest = new double[test.length - removeRow.length][test[0].length];

        for (int i = 0, j = 0, k = 0; i < test.length; i++) {
            if (j < removeRow.length) {
                if (i == removeRow[j][0]) {
            newTest[k][0] = test[i][0];


Cannot obtain value of local or argument as it is not available at this instruction pointer, possibly because it has been optimized away

I found that I had the same problem when I was running a project and debugging by attaching to an IIS process. I also was running in Debug mode with optimizations turned off. While I thought the code compiled fine, when I detached and tried to compile, one of the references was not found. This was due to another developer here that made modifications and changed the location of the reference. The reference did not show up with the alert symbol, so I thought everything was fine until I did the compilation. Once fixing the reference and running again it worked.

How to set editable true/false EditText in Android programmatically?

try this,

EditText editText=(EditText)findViewById(;


It works fine...

Fastest way to serialize and deserialize .NET objects

I took the liberty of feeding your classes into the CGbR generator. Because it is in an early stage it doesn't support DateTime yet, so I simply replaced it with long. The generated serialization code looks like this:

public int Size
        var size = 24;
        // Add size for collections and strings
        size += Cts == null ? 0 : Cts.Count * 4;
        size += Tes == null ? 0 : Tes.Count * 4;
        size += Code == null ? 0 : Code.Length;
        size += Message == null ? 0 : Message.Length;

        return size;              

public byte[] ToBytes(byte[] bytes, ref int index)
    if (index + Size > bytes.Length)
        throw new ArgumentOutOfRangeException("index", "Object does not fit in array");

    // Convert Cts
    // Two bytes length information for each dimension
    GeneratorByteConverter.Include((ushort)(Cts == null ? 0 : Cts.Count), bytes, ref index);
    if (Cts != null)
        for(var i = 0; i < Cts.Count; i++)
            var value = Cts[i];
            value.ToBytes(bytes, ref index);
    // Convert Tes
    // Two bytes length information for each dimension
    GeneratorByteConverter.Include((ushort)(Tes == null ? 0 : Tes.Count), bytes, ref index);
    if (Tes != null)
        for(var i = 0; i < Tes.Count; i++)
            var value = Tes[i];
            value.ToBytes(bytes, ref index);
    // Convert Code
    GeneratorByteConverter.Include(Code, bytes, ref index);
    // Convert Message
    GeneratorByteConverter.Include(Message, bytes, ref index);
    // Convert StartDate
    GeneratorByteConverter.Include(StartDate.ToBinary(), bytes, ref index);
    // Convert EndDate
    GeneratorByteConverter.Include(EndDate.ToBinary(), bytes, ref index);
    return bytes;

public Td FromBytes(byte[] bytes, ref int index)
    // Read Cts
    var ctsLength = GeneratorByteConverter.ToUInt16(bytes, ref index);
    var tempCts = new List<Ct>(ctsLength);
    for (var i = 0; i < ctsLength; i++)
        var value = new Ct().FromBytes(bytes, ref index);
    Cts = tempCts;
    // Read Tes
    var tesLength = GeneratorByteConverter.ToUInt16(bytes, ref index);
    var tempTes = new List<Te>(tesLength);
    for (var i = 0; i < tesLength; i++)
        var value = new Te().FromBytes(bytes, ref index);
    Tes = tempTes;
    // Read Code
    Code = GeneratorByteConverter.GetString(bytes, ref index);
    // Read Message
    Message = GeneratorByteConverter.GetString(bytes, ref index);
    // Read StartDate
    StartDate = DateTime.FromBinary(GeneratorByteConverter.ToInt64(bytes, ref index));
    // Read EndDate
    EndDate = DateTime.FromBinary(GeneratorByteConverter.ToInt64(bytes, ref index));

    return this;

I created a list of sample objects like this:

var objects = new List<Td>();
for (int i = 0; i < 1000; i++)
    var obj = new Td
        Message = "Hello my friend",
        Code = "Some code that can be put here",
        StartDate = DateTime.Now.AddDays(-7),
        EndDate = DateTime.Now.AddDays(2),
        Cts = new List<Ct>(),
        Tes = new List<Te>()
    for (int j = 0; j < 10; j++)
        obj.Cts.Add(new Ct { Foo = i * j });
        obj.Tes.Add(new Te { Bar = i + j });

Results on my machine in Release build:

var watch = new Stopwatch();
var bytes = BinarySerializer.SerializeMany(objects);

Size: 149000 bytes

Time: 2.059ms 3.13ms

Edit: Starting with CGbR 0.4.3 the binary serializer supports DateTime. Unfortunately the DateTime.ToBinary method is insanely slow. I will replace it with somehting faster soon.

Edit2: When using UTC DateTime by invoking ToUniversalTime() the performance is restored and clocks in at 1.669ms.

Running a shell script through Cygwin on Windows

If you don't mind always including .sh on the script file name, then you can keep the same script for Cygwin and Unix (Macbook).

To illustrate:
1. Always include .sh to your script file name, e.g.,
2. looks like the following as an example:
#!/bin/bash echo '$0 = ' $0 echo '$1 = ' $1 filepath=$1 3. On Windows with Cygwin, you type "" to run
4. On a Unix, you also type "" to run

Note: On Windows, you need to use the file explorer to do following once:
1. Open the file explorer
2. Right-click on a file with .sh extension, like
3. Open with... -> Select sh.exe
After this, your Windows 10 remembers to execute all .sh files with sh.exe.

Note: Using this method, you do not need to prepend your script file name with bash to run

What is the most efficient way to create HTML elements using jQuery?

I am using jquery.min v2.0.3 . It's for me better to use following:

var select = jQuery("#selecter");
jQuery("`<option/>`",{value: someValue, text: someText}).appendTo(select);

as following:

var select = jQuery("#selecter");
jQuery(document.createElement('option')).prop({value: someValue, text: someText}).appendTo(select);

Processing time of first code is much lower than second code.

How can I merge two MySQL tables?

If you need to do it manually, one time:

First, merge in a temporary table, with something like:

create table MERGED as select * from table 1 UNION select * from table 2

Then, identify the primary key constraints with something like


Where PK is the primary key field...

Solve the duplicates.

Rename the table.

[edited - removed brackets in the UNION query, which was causing the error in the comment below]

WCF error - There was no endpoint listening at

I was getting the same error with a service access. It was working in browser, but wasnt working when I try to access it in my application. I changed application pool from appPoolIdentity to NetworkService, and it start working. Seems like a permission issue to me.

Extension mysqli is missing, phpmyadmin doesn't work

sudo apt-get install php5-mysql
sudo apt-get install php5-mysqlnd 

try both of alternatively it works for me

Using a string variable as a variable name

You can use exec for that:

>>> foo = "bar"
>>> exec(foo + " = 'something else'")
>>> print bar
something else

Make a td fixed size (width,height) while rest of td's can expand

This will take care of the empty td:

<td style="min-width: 20px;"></td>

How can I count the number of children?

You can use .length, like this:

var count = $("ul li").length;

.length tells how many matches the selector found, so this counts how many <li> under <ul> elements you have...if there are sub-children, use "ul > li" instead to get only direct children. If you have other <ul> elements in your page, just change the selector to match only his one, for example if it has an ID you'd use "#myListID > li".

In other situations where you don't know the child type, you can use the * (wildcard) selector, or .children(), like this:

var count = $(".parentSelector > *").length;


var count = $(".parentSelector").children().length;

How do I add a project as a dependency of another project?

Assuming the MyEjbProject is not another Maven Project you own or want to build with maven, you could use system dependencies to link to the existing jar file of the project like so


That said it is usually the better (and preferred way) to install the package to the repository either by making it a maven project and building it or installing it the way you already seem to do.

If they are, however, dependent on each other, you can always create a separate parent project (has to be a "pom" project) declaring the two other projects as its "modules". (The child projects would not have to declare the third project as their parent). As a consequence you'd get a new directory for the new parent project, where you'd also quite probably put the two independent projects like this:

|- pom.xml
|- MyEJBProject
|   `- pom.xml
`- MyWarProject
    `- pom.xml

The parent project would get a "modules" section to name all the child modules. The aggregator would then use the dependencies in the child modules to actually find out the order in which the projects are to be built)



That way the projects can relate to each other but (once they are installed in the local repository) still be used independently as artifacts in other projects

Finally, if your projects are not in related directories, you might try to give them as relative modules:

 |- mywarproject
 |   `pom.xml
 |- myejbproject
 |   `pom.xml
 `- parent

now you could just do this (worked in maven 2, just tried it):


Sending email from Command-line via outlook without having to click send

Send SMS/Text Messages from Command Line with VBScript!

If VBA meets the rules for VB Script then it can be called from command line by simply placing it into a text file - in this case there's no need to specifically open Outlook.

I had a need to send automated text messages to myself from the command line, so I used the code below, which is just a compressed version of @Geoff's answer above.

Most mobile phone carriers worldwide provide an email address "version" of your mobile phone number. For example in Canada with Rogers or Chatr Wireless, an email sent to <YourPhoneNumber> will be immediately delivered to your Rogers/Chatr phone as a text message.

* You may need to "authorize" the first message on your phone, and some carriers may charge an additional fee for theses message although as far as I know, all Canadian carriers provide this little-known service for free. Check your carrier's website for details.

There are further instructions and various compiled lists of worldwide carrier's Email-to-Text addresses available online such as this and this and this.

Code & Instructions

  1. Copy the code below and paste into a new file in your favorite text editor.
  2. Save the file with any name with a .VBS extension, such as TextMyself.vbs.

That's all!
Just double-click the file to send a test message, or else run it from a batch file using START.

Sub SendMessage()
    Const EmailToSMSAddy = "[email protected]"
    Dim objOutlookRecip
    With CreateObject("Outlook.Application").CreateItem(0)
        Set objOutlookRecip = .Recipients.Add(EmailToSMSAddy)
        objOutlookRecip.Type = 1
        .Subject = "The computer needs your attention!"
        .Body = "Go see why Windows Command Line is texting you!"
    End With
End Sub

Example Batch File Usage:

START x:\mypath\TextMyself.vbs

Of course there are endless possible ways this could be adapted and customized to suit various practical or creative needs.

What does the "@" symbol do in SQL?

@ followed by a number is the parameters in the order they're listed in a function.

How to hash some string with sha256 in Java?

You can use MessageDigest in the following way:

public static String getSHA256(String data){
    StringBuffer sb = new StringBuffer();
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        byte byteData[] = md.digest();

        for (int i = 0; i < byteData.length; i++) {
         sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
    } catch(Exception e){
    return sb.toString();

Why are iframes considered dangerous and a security risk?

As soon as you're displaying content from another domain, you're basically trusting that domain not to serve-up malware.

There's nothing wrong with iframes per se. If you control the content of the iframe, they're perfectly safe.

How to distinguish between left and right mouse click with jQuery

With jquery you can use event object type

jQuery(".element").on("click contextmenu", function(e){
   if(e.type == "contextmenu") {
       alert("Right click");

Hive: how to show all partitions of a table?

hive> show partitions table_name;

What's the difference between an element and a node in XML?

A node is defined as:

the smallest unit of a valid, complete structure in a document.

or as:

An object in the tree view that serves as a container to hold related objects.

Now their are many different kinds of nodes as an elements node, an attribute node etc.

Using for loop inside of a JSP

You concrete problem is caused because you're mixing discouraged and old school scriptlets <% %> with its successor EL ${}. They do not share the same variable scope. The allFestivals is not available in scriptlet scope and the i is not available in EL scope.

You should install JSTL (<-- click the link for instructions) and declare it in top of JSP as follows:

<%@taglib prefix="c" uri=""%>

and then iterate over the list as follows:

<c:forEach items="${allFestivals}" var="festival">

(beware of possible XSS attack holes, use <c:out> accordingly)

Don't forget to remove the <jsp:useBean> as it has no utter value here when you're using a servlet as model-and-view controller. It would only lead to confusion. See also our servlets wiki page. Further you would do yourself a favour to disable scriptlets by the following entry in web.xml so that you won't accidently use them:


Listing files in a directory matching a pattern in Java

See File#listFiles(FilenameFilter).

File dir = new File(".");
File [] files = dir.listFiles(new FilenameFilter() {
    public boolean accept(File dir, String name) {
        return name.endsWith(".xml");

for (File xmlfile : files) {

Selected value for JSP drop down using JSTL

I think above examples are correct. but you dont' really need to set

request.setAttribute("selectedDept", selectedDept);

you can reuse that info from JSTL, just do something like this..

<!DOCTYPE html>
<html lang="en">
<%@taglib prefix="c" uri="" %>
<%@taglib prefix="fn" uri="" %>
    <script src="../js/jquery-1.8.1.min.js"></script>
    <c:set var="authors" value="aaa,bbb,ccc,ddd,eee,fff,ggg" scope="application" />
    <c:out value="Before : ${param.Author}"/>
    <form action="TestSelect.action">
            <select id="Author" name="Author">
                <c:forEach items="${fn:split(authors, ',')}" var="author">
                    <option value="${author}" ${author == param.Author ? 'selected' : ''}>${author}</option>
        <button type="submit" value="submit" name="Submit"></button>
        <c:out value="After :   ${param.Author}"/>

How to specify multiple return types using type-hints

From the documentation

class typing.Union

Union type; Union[X, Y] means either X or Y.

Hence the proper way to represent more than one return data type is

from typing import Union

def foo(client_id: str) -> Union[list,bool]

But do note that typing is not enforced. Python continues to remain a dynamically-typed language. The annotation syntax has been developed to help during the development of the code prior to being released into production. As PEP 484 states, "no type checking happens at runtime."

>>> def foo(a:str) -> list:
...     return("Works")
>>> foo(1)

As you can see I am passing a int value and returning a str. However the __annotations__ will be set to the respective values.

>>> foo.__annotations__ 
{'return': <class 'list'>, 'a': <class 'str'>}

Please Go through PEP 483 for more about Type hints. Also see What are Type hints in Python 3.5?

Kindly note that this is available only for Python 3.5 and upwards. This is mentioned clearly in PEP 484.

How to get enum value by string or int

Here is an example to get string/value

    public enum Suit
        Spades = 0x10,
        Hearts = 0x11,
        Clubs = 0x12,
        Diamonds = 0x13

    private void print_suit()
        foreach (var _suit in Enum.GetValues(typeof(Suit)))
            int suitValue = (byte)(Suit)Enum.Parse(typeof(Suit), _suit.ToString());
            MessageBox.Show(_suit.ToString() + " value is 0x" + suitValue.ToString("X2"));

    Result of Message Boxes
    Spade value is 0x10
    Hearts value is 0x11
    Clubs value is 0x12
    Diamonds value is 0x13

How to study design patterns?

I have found that it is a bit hard to comprehend or understand the benefits of some patterns until one understands the problems they solve and the other (worse) ways the problems have been implemented.

Other than the GOF and POSA books I have not really read any so I can't give you other recommendations. Really you just have to have an understanding of the problems domains and I think that many less experienced developers may not be able to appreciate the benefits of patterns. This is no slight against them. It is a lot easier to embrace, understand and appreciate good solutions when one has to struggle with poor alternatives first.

Good luck

Loop timer in JavaScript

I believe you are looking for setInterval()

Default fetch type for one-to-one, many-to-one and one-to-many in Hibernate

To answer your question, Hibernate is an implementation of the JPA standard. Hibernate has its own quirks of operation, but as per the Hibernate docs

By default, Hibernate uses lazy select fetching for collections and lazy proxy fetching for single-valued associations. These defaults make sense for most associations in the majority of applications.

So Hibernate will always load any object using a lazy fetching strategy, no matter what type of relationship you have declared. It will use a lazy proxy (which should be uninitialized but not null) for a single object in a one-to-one or many-to-one relationship, and a null collection that it will hydrate with values when you attempt to access it.

It should be understood that Hibernate will only attempt to fill these objects with values when you attempt to access the object, unless you specify fetchType.EAGER.

VS2010 command prompt gives error: Cannot determine the location of the VS Common Tools folder

I had this problem when I installed something that created a user environment PATH variable. My TeamCity build agent was running as a service under my own username and it found the user PATH variable instead of the machine PATH variable. With the wrong path variable, it couldn't find much of anything and gave this error.

jQuery see if any or no checkboxes are selected

You can do this:

  if ($('#form_id :checkbox:checked').length > 0){
    // one or more checkboxes are checked
   // no checkboxes are checked


  • :checkbox filter selector selects all checkbox.
  • :checked will select checked checkboxes
  • length will give the number of checked ones there

Synchronous Requests in Node.js

You can use retus to make cross-platform synchronous HTTP requests:

const retus = require("retus");

const { body } = retus("");
//=> "<!doctype html>..."

That's it!

Failed to instantiate module [$injector:unpr] Unknown provider: $routeProvider

The ngRoute module is no longer part of the core angular.js file. If you are continuing to use $routeProvider then you will now need to include angular-route.js in your HTML:

<script src="angular.js">
<script src="angular-route.js">

API Reference

You also have to add ngRoute as a dependency for your application:

var app = angular.module('MyApp', ['ngRoute', ...]);

If instead you are planning on using angular-ui-router or the like then just remove the $routeProvider dependency from your module .config() and substitute it with the relevant provider of choice (e.g. $stateProvider). You would then use the ui.router dependency:

var app = angular.module('MyApp', ['ui.router', ...]);

How do I download a file from the internet to my linux server with Bash

Using wget

wget -O /tmp/myfile ''

or curl:

curl -o /tmp/myfile ''

How to check type of object in Python?

use isinstance(v, type_name) or type(v) is type_name or type(v) == type_name,

where type_name can be one of the following:

  • None
  • bool
  • int
  • float
  • complex
  • str
  • list
  • tuple
  • set
  • dict

and, of course,

  • custom types (classes)

How do I make a LinearLayout scrollable?

<ScrollView xmlns:android="" 


        Your views go here...



Android Facebook integration with invalid key hash

You must create two key hashes, one for Debug and one for Release.

For the Debug key hash:

On OS X, run:

keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64

On Windows, run:

keytool -exportcert -alias androiddebugkey -keystore %HOMEPATH%\.android\debug.keystore | openssl sha1 -binary | openssl

Debug key hashes source

For the Release key hash:

On OS X, run (replace what is between <> with your values):

keytool -exportcert -alias <RELEASE_KEY_ALIAS> -keystore <RELEASE_KEY_PATH> | openssl sha1 -binary | openssl base64

On Windows, use (replace what is between <> with your values):

keytool -exportcert -alias <RELEASE_KEY_ALIAS> -keystore <RELEASE_KEY_PATH> | openssl sha1 -binary | openssl base64

Release key hashes source

How do I execute a command and get the output of the command within C++ using POSIX?

I'd use popen() (++waqas).

But sometimes you need reading and writing...

It seems like nobody does things the hard way any more.

(Assuming a Unix/Linux/Mac environment, or perhaps Windows with a POSIX compatibility layer...)

  READ_FD  = 0,
  WRITE_FD = 1


  int       parentToChild[2];
  int       childToParent[2];
  pid_t     pid;
  string    dataReadFromChild;
  char      buffer[BUFFER_SIZE + 1];
  ssize_t   readResult;
  int       status;

  ASSERT_IS(0, pipe(parentToChild));
  ASSERT_IS(0, pipe(childToParent));

  switch (pid = fork())
    case -1:
      FAIL("Fork failed");

    case 0: /* Child */
      ASSERT_NOT(-1, dup2(parentToChild[READ_FD], STDIN_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDOUT_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDERR_FILENO));
      ASSERT_IS(0, close(parentToChild [WRITE_FD]));
      ASSERT_IS(0, close(childToParent [READ_FD]));

      /*     file, arg0, arg1,  arg2 */
      execlp("ls", "ls", "-al", "--color");

      FAIL("This line should never be reached!!!");

    default: /* Parent */
      cout << "Child " << pid << " process running..." << endl;

      ASSERT_IS(0, close(parentToChild [READ_FD]));
      ASSERT_IS(0, close(childToParent [WRITE_FD]));

      while (true)
        switch (readResult = read(childToParent[READ_FD],
                                  buffer, BUFFER_SIZE))
          case 0: /* End-of-File, or non-blocking read. */
            cout << "End of file reached..."         << endl
                 << "Data received was ("
                 << dataReadFromChild.size() << "): " << endl
                 << dataReadFromChild                << endl;

            ASSERT_IS(pid, waitpid(pid, & status, 0));

            cout << endl
                 << "Child exit staus is:  " << WEXITSTATUS(status) << endl
                 << endl;


          case -1:
            if ((errno == EINTR) || (errno == EAGAIN))
              errno = 0;
              FAIL("read() failed");

            dataReadFromChild . append(buffer, readResult);
      } /* while (true) */
  } /* switch (pid = fork())*/

You also might want to play around with select() and non-blocking reads.

fd_set          readfds;
struct timeval  timeout;

timeout.tv_sec  = 0;    /* Seconds */
timeout.tv_usec = 1000; /* Microseconds */

FD_SET(childToParent[READ_FD], &readfds);

switch (select (1 + childToParent[READ_FD], &readfds, (fd_set*)NULL, (fd_set*)NULL, & timeout))
  case 0: /* Timeout expired */

  case -1:
    if ((errno == EINTR) || (errno == EAGAIN))
      errno = 0;
      FAIL("Select() Failed");

  case 1:  /* We have input */
    readResult = read(childToParent[READ_FD], buffer, BUFFER_SIZE);
    // However you want to handle it...

    FAIL("How did we see input on more than one file descriptor?");

What is the minimum I have to do to create an RPM file?

For quick RPM building, check out Togo:

The project has a Quick-Start guide and I was able to create a basic RPM in less than 3 minutes.

Example using the data provided in the original question:

1) Create the project directory using the script:

$ togo project create foobar; cd foobar

2) Make your desired directory structure under ./root and copy your files into it:

$ mkdir -p root/etc; cp /path/to/foobar.conf root/etc/
$ mkdir -p root/usr/bin; cp /path/to/foobar root/usr/bin/

3) Exclude system-owned directories from your RPM's ownership:

$ togo file exclude root/etc root/usr/bin

4) (OPTIONAL) Modify the generated spec to change your package description/dependencies/version/whatever, etc.:

$ vi spec/header

5) Build the RPM:

$ togo build package

-and your RPM is spit out into the ./rpms directory.

Keylistener in Javascript

The code is

document.addEventListener('keydown', function(event){
} );

This return the ascii code of the key. If you need the key representation, use event.key (This will return 'a', 'o', 'Alt'...)

Delete all objects in a list


mylist.clear()  # Added in Python 3.3
del mylist[:]

are probably the best ways to do this. The rest of this answer tries to explain why some of your other efforts didn't work.

cpython at least works on reference counting to determine when objects will be deleted. Here you have multiple references to the same objects. a refers to the same object that c[0] references. When you loop over c (for i in c:), at some point i also refers to that same object. the del keyword removes a single reference, so:

for i in c:
   del i

creates a reference to an object in c and then deletes that reference -- but the object still has other references (one stored in c for example) so it will persist.

In the same way:

def kill(self):
    del self

only deletes a reference to the object in that method. One way to remove all the references from a list is to use slice assignment:

mylist = list(range(10000))
mylist[:] = []

Apparently you can also delete the slice to remove objects in place:

del mylist[:]  #This will implicitly call the `__delslice__` or `__delitem__` method.

This will remove all the references from mylist and also remove the references from anything that refers to mylist. Compared that to simply deleting the list -- e.g.

mylist = list(range(10000))
b = mylist
del mylist
#here we didn't get all the references to the objects we created ...
print(b) #[0, 1, 2, 3, 4, ...]

Finally, more recent python revisions have added a clear method which does the same thing that del mylist[:] does.

mylist = [1, 2, 3]

Difference between shared objects (.so), static libraries (.a), and DLL's (.so)?

A static library(.a) is a library that can be linked directly into the final executable produced by the linker,it is contained in it and there is no need to have the library into the system where the executable will be deployed.

A shared library(.so) is a library that is linked but not embedded in the final executable, so will be loaded when the executable is launched and need to be present in the system where the executable is deployed.

A dynamic link library on windows(.dll) is like a shared library(.so) on linux but there are some differences between the two implementations that are related to the OS (Windows vs Linux) :

A DLL can define two kinds of functions: exported and internal. The exported functions are intended to be called by other modules, as well as from within the DLL where they are defined. Internal functions are typically intended to be called only from within the DLL where they are defined.

An SO library on Linux doesn't need special export statement to indicate exportable symbols, since all symbols are available to an interrogating process.

Launch Failed. Binary not found. CDT on Eclipse Helios

Seems like having "Build Automatically" under the Project menu ought to take care of all of this. It does for Java.

How can I get query parameters from a URL in Vue.js?

You can use vue-router.I have an example below:


new Vue({
  el: "#app",
  data: {
    name: '',
    lastName: ''
  beforeRouteEnter(to, from, next) {
      if(Object.keys(to.query).length !== 0) { //if the url has query (?query)
        next(vm => { =
         vm.lastName = to.query.lastName

Note: In beforeRouteEnter function we cannot access the component's properties like: this.propertyName.That's why i have pass the vm to next function.It is the recommented way to access the vue instance.Actually the vm it stands for vue instance

Why doesn't calling a Python string method do anything unless you assign its output?

Example for String Methods

Given a list of filenames, we want to rename all the files with extension hpp to the extension h. To do this, we would like to generate a new list called newfilenames, consisting of the new filenames. Fill in the blanks in the code using any of the methods you’ve learned thus far, like a for loop or a list comprehension.

filenames = ["program.c", "stdio.hpp", "sample.hpp", "a.out", "math.hpp", "hpp.out"]
# Generate newfilenames as a list containing the new filenames
# using as many lines of code as your chosen method requires.
newfilenames = []
for i in filenames:
    if i.endswith(".hpp"):
        x = i.replace("hpp", "h")

# Should be ["program.c", "stdio.h", "sample.h", "a.out", "math.h", "hpp.out"]

Colorized grep -- viewing the entire file with highlighted matches

Alternatively you can use The Silver Searcher and do

ag <search> --passthrough

inherit from two classes in C#

Make two interfaces IA and IB:

public interface IA
    public void methodA(int value);

public interface IB
    public void methodB(int value);

Next make A implement IA and B implement IB.

public class A : IA
    public int fooA { get; set; }
    public void methodA(int value) { fooA = value; }

public class B : IB
    public int fooB { get; set; }
    public void methodB(int value) { fooB = value; }

Then implement your C class as follows:

public class C : IA, IB
    private A _a;
    private B _b;

    public C(A _a, B _b)
        this._a = _a;
        this._b = _b;

    public void methodA(int value) { _a.methodA(value); }
    public void methodB(int value) { _b.methodB(value); }

Generally this is a poor design overall because you can have both A and B implement a method with the same name and variable types such as foo(int bar) and you will need to decide how to implement it, or if you just call foo(bar) on both _a and _b. As suggested elsewhere you should consider a .A and .B properties instead of combining the two classes.

How to set a Fragment tag by code?

Yes. So the only way is at transaction time, e.g. using add, replace, or as part of the layout.

I determined this through an examination of the compatibility sources as I briefly looked for similar at some point in the past.

What does Include() do in LINQ?

Let's say for instance you want to get a list of all your customers:

var customers = context.Customers.ToList();

And let's assume that each Customer object has a reference to its set of Orders, and that each Order has references to LineItems which may also reference a Product.

As you can see, selecting a top-level object with many related entities could result in a query that needs to pull in data from many sources. As a performance measure, Include() allows you to indicate which related entities should be read from the database as part of the same query.

Using the same example, this might bring in all of the related order headers, but none of the other records:

var customersWithOrderDetail = context.Customers.Include("Orders").ToList();

As a final point since you asked for SQL, the first statement without Include() could generate a simple statement:

SELECT * FROM Customers;

The final statement which calls Include("Orders") may look like this:

FROM Customers JOIN Orders ON Customers.Id = Orders.CustomerId;

MVC Redirect to View from jQuery with parameters

If your click handler is successfully called then this should work:

$('#results').on('click', '.item', function () {
            var NestId = $(this).data('id');
            var url = "/Artists/Details?NestId=" + NestId; 
            window.location.href = url; 

EDIT: In this particular case given that the action method parameter is a string which is nullable, then if NestId == null, won't cause any exception at all, given that the ModelBinder won't complain about it.

Set colspan dynamically with jquery

Setting colspan="0" is support only in firefox.

In other browsers we can get around it with:

// Auto calculate table colspan if set to 0
var colCount = 0;
    colCount = 0;
        if ($(this).attr('colspan')){
            colCount += +$(this).attr('colspan');
        } else {
$(this).attr("colspan", colCount);

Good MapReduce examples

From time to time I present MR concepts to people. I find processing tasks familiar to people and then map them to the MR paradigm.

Usually I take two things:

  1. Group By / Aggregations. Here the advantage of the shuffling stage is clear. An explanation that shuffling is also distributed sort + an explanation of distributed sort algorithm also helps.

  2. Join of two tables. People working with DB are familiar with the concept and its scalability problem. Show how it can be done in MR.

SQL Server: SELECT only the rows with MAX(DATE)

Try to avoid IN use JOIN

SELECT SQL_CALC_FOUND_ROWS *  FROM (SELECT  msisdn, callid, Change_color, play_file_name, date_played FROM insert_log
   WHERE play_file_name NOT IN('Prompt1','Conclusion_Prompt_1','silent')
 ORDER BY callid ASC) t1 JOIN (SELECT MAX(date_played) AS date_played FROM insert_log GROUP BY callid) t2 ON t1.date_played=t2.date_played

Using Django time/date widgets in custom form

Starting in Django 1.2 RC1, if you're using the Django admin date picker widge trick, the following has to be added to your template, or you'll see the calendar icon url being referenced through "/missing-admin-media-prefix/".

{% load adminmedia %} /* At the top of the template. */

/* In the head section of the template. */
<script type="text/javascript">
window.__admin_media_prefix__ = "{% filter escapejs %}{% admin_media_prefix %}{% endfilter %}";

How do I install PHP cURL on Linux Debian?

Whatever approach you take, make sure in the end that you have an updated version of curl and libcurl. You can do curl --version and see the versions.

Here's what I did to get the latest curl version installed in Ubuntu:

  1. sudo add-apt-repository "deb wily main"
  2. sudo apt-get update
  3. sudo apt-get install curl

How to configure socket connect timeout

I solved the problem by using Socket.ConnectAsync Method instead of Socket.Connect Method. After invoking the Socket.ConnectAsync(SocketAsyncEventArgs), start a timer (timer_connection), if time is up, check whether socket connection is connected (if(m_clientSocket.Connected)), if not, pop up timeout error.

private void connect(string ipAdd,string port)
            SocketAsyncEventArgs e=new SocketAsyncEventArgs();

            m_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            IPAddress ip = IPAddress.Parse(serverIp);
            int iPortNo = System.Convert.ToInt16(serverPort);
            IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);

            e.RemoteEndPoint = ipEnd;
            e.UserToken = m_clientSocket;
            e.Completed+=new EventHandler<SocketAsyncEventArgs>(e_Completed);                

            if (timer_connection != null)
                timer_connection = new Timer();
            timer_connection.Interval = 2000;
            timer_connection.Tick+=new EventHandler(timer_connection_Tick);
        catch (SocketException se)
            lb_connectStatus.Text = "Connection Failed";
private void e_Completed(object sender,SocketAsyncEventArgs e)
        lb_connectStatus.Text = "Connection Established";
    private void timer_connection_Tick(object sender, EventArgs e)
        if (!m_clientSocket.Connected)
            MessageBox.Show("Connection Timeout");
            //m_clientSocket = null;


BOOLEAN or TINYINT confusion

MySQL does not have internal boolean data type. It uses the smallest integer data type - TINYINT.

The BOOLEAN and BOOL are equivalents of TINYINT(1), because they are synonyms.

Try to create this table -


Then run SHOW CREATE TABLE, you will get this output -

CREATE TABLE `table1` (
  `column1` tinyint(1) DEFAULT NULL

How to keep one variable constant with other one changing with row in excel

Placing a $ in front of the row value to keep constant worked well for me. e.g.


Where are $_SESSION variables stored?

As Mr. Taylor pointed out this is usually set in php.ini. Usually they are stored as files in a specific directory.

printf a variable in C

Your printf needs a format string:

printf("%d\n", x);

This reference page gives details on how to use printf and related functions.

Sorting Values of Set

You're using the default comparator to sort a Set<String>. In this case, that means lexicographic order. Lexicographically, "12" comes before "15", comes before "5".

Either use a Set<Integer>:

Set<Integer> set=new HashSet<Integer>();

Or use a different comparator:

Collections.sort(list, new Comparator<String>() {
    public int compare(String a, String b) {
        return Integer.parseInt(a) - Integer.parseInt(b);

How to emulate a do-while loop in Python?

do {
} while (condition())


while True:
  if not condition():

You can do a function:

def do_while(stuff, condition):
  while condition(stuff()):

But 1) It's ugly. 2) Condition should be a function with one parameter, supposed to be filled by stuff (it's the only reason not to use the classic while loop.)

what is the size of an enum type data in C++?

An enum is nearly an integer. To simplify a lot

enum yourenum { a, b, c };

is almost like

#define a 0
#define b 1
#define c 2

Of course, it is not really true. I'm trying to explain that enum are some kind of coding...

Formatting floats in a numpy array

In order to make numpy display float arrays in an arbitrary format, you can define a custom function that takes a float value as its input and returns a formatted string:

In [1]: float_formatter = "{:.2f}".format

The f here means fixed-point format (not 'scientific'), and the .2 means two decimal places (you can read more about string formatting here).

Let's test it out with a float value:

In [2]: float_formatter(1.234567E3)
Out[2]: '1234.57'

To make numpy print all float arrays this way, you can pass the formatter= argument to np.set_printoptions:

In [3]: np.set_printoptions(formatter={'float_kind':float_formatter})

Now numpy will print all float arrays this way:

In [4]: np.random.randn(5) * 10
Out[4]: array([5.25, 3.91, 0.04, -1.53, 6.68]

Note that this only affects numpy arrays, not scalars:

In [5]: np.pi
Out[5]: 3.141592653589793

It also won't affect non-floats, complex floats etc - you will need to define separate formatters for other scalar types.

You should also be aware that this only affects how numpy displays float values - the actual values that will be used in computations will retain their original precision.

For example:

In [6]: a = np.array([1E-9])

In [7]: a
Out[7]: array([0.00])

In [8]: a == 0
Out[8]: array([False], dtype=bool)

numpy prints a as if it were equal to 0, but it is not - it still equals 1E-9.

If you actually want to round the values in your array in a way that affects how they will be used in calculations, you should use np.round, as others have already pointed out.

Concatenate two char* strings in a C program

Here is a working solution:

#include <stdio.h>
#include <string.h>

int main(int argc, char** argv) 
      char str1[16];
      char str2[16];
      strcpy(str1, "sssss");
      strcpy(str2, "kkkk");
      strcat(str1, str2);
      printf("%s", str1);
      return 0;



You have to allocate memory for your strings. In the above code, I declare str1 and str2 as character arrays containing 16 characters. I used strcpy to copy characters of string literals into them, and strcat to append the characters of str2 to the end of str1. Here is how these character arrays look like during the execution of the program:

After declaration (both are empty): 
str1: [][][][][][][][][][][][][][][][][][][][] 
str2: [][][][][][][][][][][][][][][][][][][][]

After calling strcpy (\0 is the string terminator zero byte): 
str1: [s][s][s][s][s][\0][][][][][][][][][][][][][][] 
str2: [k][k][k][k][\0][][][][][][][][][][][][][][][]

After calling strcat: 
str1: [s][s][s][s][s][k][k][k][k][\0][][][][][][][][][][] 
str2: [k][k][k][k][\0][][][][][][][][][][][][][][][]

What is the difference between Double.parseDouble(String) and Double.valueOf(String)?

If you want to convert string to double data type then most choose parseDouble() method. See the example code:

String str = "123.67";
double d = parseDouble(str);

You will get the value in double. See the StringToDouble tutorial at tutorialData.

Select from one table where not in another

You can LEFT JOIN the two tables. If there is no corresponding row in the second table, the values will be NULL.

SELECT id FROM partmaster LEFT JOIN product_details ON (...) WHERE product_details.part_num IS NULL

Pandas - Get first row value of a given column

In a general way, if you want to pick up the first N rows from the J column from pandas dataframe the best way to do this is:

data = dataframe[0:N][:,J]

Using JQuery hover with HTML image map

I found this wonderful mapping script (mapper.js) that I have used in the past. What's different about it is you can hover over the map or a link on your page to make the map area highlight. Sadly it's written in javascript and requires a lot of in-line coding in the HTML - I would love to see this script ported over to jQuery :P

Also, check out all the demos! I think this example could almost be made into a simple online game (without using flash) - make sure you click on the different camera angles.

Android: How to stretch an image to the screen width while maintaining aspect ratio?

I've been struggling with this problem in one form or another for AGES, thank you, Thank You, THANK YOU.... :)

I just wanted to point out that you can get a generalizable solution from what Bob Lee's done by just extending View and overriding onMeasure. That way you can use this with any drawable you want, and it won't break if there's no image:

    public class CardImageView extends View {
        public CardImageView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);

        public CardImageView(Context context, AttributeSet attrs) {
            super(context, attrs);

        public CardImageView(Context context) {

        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            Drawable bg = getBackground();
            if (bg != null) {
                int width = MeasureSpec.getSize(widthMeasureSpec);
                int height = width * bg.getIntrinsicHeight() / bg.getIntrinsicWidth();
            else {
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);

Binding IIS Express to an IP Address

In order for IIS Express answer on any IP address, just leave the address blank, i.e:


Don't forget to restart the IIS express before the changes can take place.

How to perform a real time search and filter on a HTML table

Datatable JS plugin is also one good alternate to accomedate search feature for html table

var table = $('#example').DataTable();

// #myInput is a <input type="text"> element
$('#myInput').on( 'keyup', function () { this.value ).draw();
} );

Powershell: Get FQDN Hostname

I use the following syntax :


it does not matter if the $VM is up or down...

Importing from a relative path in Python

Approch used by me is similar to Gary Beardsley mentioned above with small change.


import os, sys
script_path = os.path.realpath(os.path.dirname(__name__))
# above mentioned steps will make 1 level up module available for import
# here Client, Server and Common all 3 can be imported.

# below mentioned import will be relative to root project
from Common import Common
from Client import Client

Omitting all xsi and xsd namespaces when serializing an object in .NET?

XmlSerializer sr = new XmlSerializer(objectToSerialize.GetType());
TextWriter xmlWriter = new StreamWriter(filename);
XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
namespaces.Add(string.Empty, string.Empty);
sr.Serialize(xmlWriter, objectToSerialize, namespaces);

Angularjs how to upload multipart form data and a file?

You can check out this method for sending image and form data altogether

<div class="form-group ml-5 mt-4" ng-app="myApp" ng-controller="myCtrl">
                    <label for="image_name">Image Name:</label>
                    <input type="text"   placeholder="Image name" ng-model="fileName" class="form-control" required>

                    <input id="file_src" type="file"   accept="image/jpeg" file-input="files"   >
            <img class="rounded mt-2 mb-2 " id="prvw_img" width="150" height="100" >
                      <button class="btn btn-info" ng-click="uploadFile()">Upload</button>

                       <div ng-show = "IsVisible" class="alert alert-info w-100 shadow mt-2" role="alert">
              <strong> {{response_msg}} </strong>
                            <div class="alert alert-danger " id="filealert"> <strong> File Size should be less than 4 MB </strong></div>

Angular JS Code

    var app = angular.module("myApp", []);
 app.directive("fileInput", function($parse){
           link: function($scope, element, attrs){
                element.on("change", function(event){
                     var files =;

                     $parse(attrs.fileInput).assign($scope, element[0].files);
 app.controller("myCtrl", function($scope, $http){
      $scope.IsVisible = false;
      $scope.uploadFile = function(){
           var form_data = new FormData();
           angular.forEach($scope.files, function(file){
                form_data.append('file', file); //form file
                                form_data.append('file_Name',$scope.fileName); //form text data
           $'upload.php', form_data,
                transformRequest: angular.identity,
                headers: {'Content-Type': undefined,'Process-Data': false}
             $scope.IsVisible = $scope.IsVisible = true;
               // alert(response);
               // $;


Link a .css on another folder

check this quick reminder of file path

Here is all you need to know about relative file paths:

  • Starting with "/" returns to the root directory and starts there
  • Starting with "../" moves one directory backwards and starts there
  • Starting with "../../" moves two directories backwards and starts there (and so on...)
  • To move forward, just start with the first subdirectory and keep moving forward

Spring default behavior for lazy-init

The lazy-init="default" setting on a bean only refers to what is set by the default-lazy-init attribute of the enclosing beans element. The implicit default value of default-lazy-init is false.

If there is no lazy-init attribute specified on a bean, it's always eagerly instantiated.

How do I stop a web page from scrolling to the top when a link is clicked that triggers JavaScript?

When calling the function, follow it by return false example:

<input  type="submit" value="Add" onclick="addNewPayment();return false;">

replace String with another in java

     String s1 = "HelloSuresh";
     String m = s1.replace("Hello","");

How to use pip with python 3.4 on windows?

Usage of pip for installation of packages in Python 3

Step 1: Install Python 3. Yes, by default an application file pip3.exe is already located there in the path (E.g.):


Step 2: Go to

>Control Panel (Local Machine) > System > Advanced system settings >

>Click on `Environment Variables` >
Set a New User Variable, for this click `New` >
Write new 'Variable name' as "PYTHON_SCRIPTS" >
Copy that path of `pip3.exe` and paste within variable value > `OK` >

>Below again find out and click on `Path` under 'system variables' >
Edit this path >
Within 'Variable value' append and paste the same path of `pip3.exe` after putting a ';' >
Click `OK`/`Apply` and come out.

Step 3: Now, open cmd bash/shell by Pressing key Windows+R.

> Write 'pip3' and press 'Enter'. If pip3 is recognized you can go ahead.

Step 4: In this same cmd

> Write path of the `pip3.exe` followed by `/pip install 'package name'`

As Example just write:

C:/Users/name/AppData/Local/Programs/Python/Python36-32/Scripts/pip install matplotlib

Press Enter now. The Package matplotlib will start getting downloaded.

Further, for upgrading any package

Open cmd bash/shell again, then

type that path of pip3.exe followed by /pip install --upgrade 'package name' Press Enter.

As Example just write:

C:/Users/name/AppData/Local/Programs/Python/Python36-32/Scripts/pip install --upgrade matplotlib

Upgrading of the package will start :)

Converting <br /> into a new line for use in a text area

The answer by @Mobilpadde is nice. But this is my solution with regex using preg_replace which might be faster according to my tests.

echo preg_replace('/<br\s?\/?>/i', "\r\n", "testing<br/><br /><BR><br>");

function function_one() {
    preg_replace('/<br\s?\/?>/i', "\r\n", "testing<br/><br /><BR><br>");

function function_two() {
    str_ireplace(['<br />','<br>','<br/>'], "\r\n", "testing<br/><br /><BR><br>");

function benchmark() {
    $count = 10000000;
    $before = microtime(true);

    for ($i=0 ; $i<$count; $i++) {

    $after = microtime(true);
    echo ($after-$before)/$i . " sec/function one\n";

    $before = microtime(true);

    for ($i=0 ; $i<$count; $i++) {

    $after = microtime(true);
    echo ($after-$before)/$i . " sec/function two\n";


1.1471637010574E-6 sec/function one (preg_replace)
1.6027762889862E-6 sec/function two (str_ireplace)

Properties private set;

This is one possible solution although not very clean:

  1. Make the property you need to expose to BAL & DAL internal
  2. Mark BAL.dll & DAL.dll Internal Visible in assemblyinfo.cs

public class Person
    public Person(int id)

    public string Name { get;  set; }
    public int Id { get; internal set; }
    public int Age { get; set; }

AssemblyInfo.cs for Entities.dll

[assembly: InternalsVisibleTo("DAL"), InternalsVisibleTo("BAL")]

That way all your internals will be visible to DAL & BAL. This may not be desirable but I'm just suggesting one possible solution.

first-child and last-child with IE8

Since :last-child is a CSS3 pseudo-class, it is not supported in IE8. I believe :first-child is supported, as it's defined in the CSS2.1 specification.

One possible solution is to simply give the last child a class name and style that class.

Another would be to use JavaScript. jQuery makes this particularly easy as it provides a :last-child pseudo-class which should work in IE8. Unfortunately, that could result in a flash of unstyled content while the DOM loads.

How to change dot size in gnuplot

The pointsize command scales the size of points, but does not affect the size of dots.

In other words, plot ... with points ps 2 will generate points of twice the normal size, but for plot ... with dots ps 2 the "ps 2" part is ignored.

You could use circular points (pt 7), which look just like dots.

Is there an equivalent of 'which' on the Windows command line?

Go get unxutils from here:

gold on windows platforms, puts all the nice unix utilities on a standard windows DOS. Been using it for years.

It has a 'which' included. Note that it's case sensitive though.

NB: to install it explode the zip somewhere and add ...\UnxUtils\usr\local\wbin\ to your system path env variable.

Change class on mouseover in directive

In general I fully agree with Jason's use of css selector, but in some cases you may not want to change the css, e.g. when using a 3rd party css-template, and rather prefer to add/remove a class on the element.

The following sample shows a simple way of adding/removing a class on ng-mouseenter/mouseleave:

<div ng-app>
    ng-class="{red: hover}"
    ng-init="hover = false"
    ng-mouseenter="hover = true"
    ng-mouseleave="hover = false">
      Test 1 2 3.

with some styling:

.red {
  background-color: red;

.italic {
  font-style: italic;
  color: black;

See running example here: jsfiddle sample

Styling on hovering is a view concern. Although the solution above sets a "hover" property in the current scope, the controller does not need to be concerned about this.

Python Pylab scatter plot error bars (the error on each point is unique)

>>> import matplotlib.pyplot as plt
>>> a = [1,3,5,7]
>>> b = [11,-2,4,19]
>>> plt.pyplot.scatter(a,b)
>>> plt.scatter(a,b)
<matplotlib.collections.PathCollection object at 0x00000000057E2CF8>
>>> c = [1,3,2,1]
>>> plt.errorbar(a,b,yerr=c, linestyle="None")
<Container object of 3 artists>

where a is your x data b is your y data c is your y error if any

note that c is the error in each direction already

jquery function setInterval

This is because you are executing the function not referencing it. You should do:


Creating a chart in Excel that ignores #N/A or blank cells

I found a way to do it.

you can do an x,y scatterplot. it will ignore null records (i.e. rows)

Set port for php artisan.php serve

when we use the

php artisan serve 

it will start with the default HTTP-server port mostly it will be 8000 when we want to run the more site in the localhost we have to change the port. Just add the --port argument:

php artisan serve --port=8081

enter image description here

SQL/mysql - Select distinct/UNIQUE but return all columns?

If I understood your problem correctly, it's similar to one I just had. You want to be able limit the usability of DISTINCT to a specified field, rather than applying it to all the data.

If you use GROUP BY without an aggregate function, which ever field you GROUP BY will be your DISTINCT filed.

If you make your query:

SELECT * from table GROUP BY field1;

It will show all your results based on a single instance of field1.

For example, if you have a table with name, address and city. A single person has multiple addresses recorded, but you just want a single address for the person, you can query as follows:

SELECT * FROM persons GROUP BY name;

The result will be that only one instance of that name will appear with its address, and the other one will be omitted from the resulting table. Caution: if your fileds have atomic values such as firstName, lastName you want to group by both.

SELECT * FROM persons GROUP BY lastName, firstName;

because if two people have the same last name and you only group by lastName, one of those persons will be omitted from the results. You need to keep those things into consideration. Hope this helps.

MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED]

mongoose.connect('mongodb://localhost:27017/').then(() => {
console.log("Connected to Database");
}).catch((err) => {
console.log("Not Connected to Database ERROR! ", err);

Better just connect to the localhost Mongoose Database only and create your own collections. Don't forget to mention the port number. (Default: 27017)

For the best view, download Mongoose-compass for MongoDB UI.

Set a Fixed div to 100% width of the parent container

On top of your lastest jsfiddle, you just missed one thing:

#sidebar_wrap {
#sidebar {
  max-width: 240px; /*This is you missed*/

But, how this will solve your problem? Simple, lets explain why is bigger than expect first.

Fixed element #sidebar will use window width size as base to get its own size, like every other fixed element, once in this element is defined width:inherit and #sidebar_wrap has 40% as value in width, then will calculate window.width * 40%, then when if your window width is bigger than your .container width, #sidebar will be bigger than #sidebar_wrap.

This is way, you must set a max-width in your #sidebar_wrap, to prevent to be bigger than #sidebar_wrap.

Check this jsfiddle that shows a working code and explain better how this works.

What is the Python equivalent of Matlab's tic and toc functions?

Usually, IPython's %time, %timeit, %prun and %lprun (if one has line_profiler installed) satisfy my profiling needs quite well. However, a use case for tic-toc-like functionality arose when I tried to profile calculations that were interactively driven, i.e., by the user's mouse motion in a GUI. I felt like spamming tics and tocs in the sources while testing interactively would be the fastest way to reveal the bottlenecks. I went with Eli Bendersky's Timer class, but wasn't fully happy, since it required me to change the indentation of my code, which can be inconvenient in some editors and confuses the version control system. Moreover, there may be the need to measure the time between points in different functions, which wouldn't work with the with statement. After trying lots of Python cleverness, here is the simple solution that I found worked best:

from time import time
_tstart_stack = []

def tic():

def toc(fmt="Elapsed: %s s"):
    print fmt % (time() - _tstart_stack.pop())

Since this works by pushing the starting times on a stack, it will work correctly for multiple levels of tics and tocs. It also allows one to change the format string of the toc statement to display additional information, which I liked about Eli's Timer class.

For some reason I got concerned with the overhead of a pure Python implementation, so I tested a C extension module as well:

#include <Python.h>
#include <mach/mach_time.h>
#define MAXDEPTH 100

uint64_t start[MAXDEPTH];
int lvl=0;

static PyObject* tic(PyObject *self, PyObject *args) {
    start[lvl++] = mach_absolute_time();

static PyObject* toc(PyObject *self, PyObject *args) {
return PyFloat_FromDouble(
        (double)(mach_absolute_time() - start[--lvl]) / 1000000000L);

static PyObject* res(PyObject *self, PyObject *args) {
    return tic(NULL, NULL), toc(NULL, NULL);

static PyMethodDef methods[] = {
    {"tic", tic, METH_NOARGS, "Start timer"},
    {"toc", toc, METH_NOARGS, "Stop timer"},
    {"res", res, METH_NOARGS, "Test timer resolution"},
    {NULL, NULL, 0, NULL}

inittictoc(void) {
    Py_InitModule("tictoc", methods);

This is for MacOSX, and I have omitted code to check if lvl is out of bounds for brevity. While tictoc.res() yields a resolution of about 50 nanoseconds on my system, I found that the jitter of measuring any Python statement is easily in the microsecond range (and much more when used from IPython). At this point, the overhead of the Python implementation becomes negligible, so that it can be used with the same confidence as the C implementation.

I found that the usefulness of the tic-toc-approach is practically limited to code blocks that take more than 10 microseconds to execute. Below that, averaging strategies like in timeit are required to get a faithful measurement.

Segmentation Fault - C

char *s  does not have some memory allocated . You need to allocate it manually in your case . You can do it as follows
s = (char *)malloc(100) ;

This would not lead to segmentation fault error as you will not be refering to an unknown location anymore

Draggable div without jQuery UI

Here is an implementation without using jQuery at all -

Embed the JS file ( in your HTML code, and put the following code -

win.onload = function(){
 tzdragg.drag('elem1, elem2, ..... elemn');
 // ^ IDs of the draggable elements separated by a comma.

And the code is also easy to learn.

How to send HTTP request in java?

You can use

Example (from here), with improvements. Included in case of link rot:

public static String executePost(String targetURL, String urlParameters) {
  HttpURLConnection connection = null;

  try {
    //Create connection
    URL url = new URL(targetURL);
    connection = (HttpURLConnection) url.openConnection();

    connection.setRequestProperty("Content-Language", "en-US");  


    //Send request
    DataOutputStream wr = new DataOutputStream (

    //Get Response  
    InputStream is = connection.getInputStream();
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));
    StringBuilder response = new StringBuilder(); // or StringBuffer if Java version 5+
    String line;
    while ((line = rd.readLine()) != null) {
    return response.toString();
  } catch (Exception e) {
    return null;
  } finally {
    if (connection != null) {

Python method for reading keypress?

from msvcrt import getch

pos = [0, 0]

def fright():
    global pos
    pos[0] += 1

def fleft():
    global pos 
    pos[0] -= 1

def fup():
    global pos
    pos[1] += 1

def fdown():
    global pos
    pos[1] -= 1

while True:
    print'Distance from zero: ', pos
    key = ord(getch())
    if key == 27: #ESC
    elif key == 13: #Enter
    elif key == 32: #Space
    elif key == 224: #Special keys (arrows, f keys, ins, del, etc.)
        key = ord(getch())
        if key == 80: #Down arrow
        elif key == 72: #Up arrow
        elif key == 75: #Left arrow
        elif key == 77: #Right arrow

ListView item background via custom selector

Never ever use a "background color" for your listview rows...

this will block every selector action (was my problem!)

good luck!

Thymeleaf: Concatenation - Could not parse as expression

You can concat many kind of expression by sorrounding your simple/complex expression between || characters:

<p th:text="|${bean.field} ! ${bean.field}|">Static content</p>

How to print a float with 2 decimal places in Java?

Try this:-

private static String getDecimalFormat(double value) {

    String getValue = String.valueOf(value).split("[.]")[1];

      if (getValue.length() == 1) {
          return String.valueOf(value).split("[.]")[0] +
                "."+ getValue.substring(0, 1) + 
                String.format("%0"+1+"d", 0);
       } else {
          return String.valueOf(value).split("[.]")[0]
            +"." + getValue.substring(0, 2);


How to get URI from an asset File?

There is no "absolute path for a file existing in the asset folder". The content of your project's assets/ folder are packaged in the APK file. Use an AssetManager object to get an InputStream on an asset.

For WebView, you can use the file Uri scheme in much the same way you would use a URL. The syntax for assets is file:///android_asset/... (note: three slashes) where the ellipsis is the path of the file from within the assets/ folder.

Get last 30 day records from today date in SQL Server

I dont know why all these complicated answers are on here but this is what I would do

where pdate >= CURRENT_TIMESTAMP -30


How can I properly handle 404 in ASP.NET MVC?

Posting an answer since my comment was too long...

It's both a comment and questions to the unicorn post/answer:

I prefer this answer over the others for it's simplicity and the fact that apparently some folks at Microsoft were consulted. I got three questions however and if they can be answered then I will call this answer the holy grail of all 404/500 error answers on the interwebs for an ASP.NET MVC (x) app.


  1. Can you update your answer with the SEO stuff from the comments pointed out by GWB (there was never any mentioning of this in your answer) - <customErrors mode="On" redirectMode="ResponseRewrite"> and <httpErrors errorMode="Custom" existingResponse="Replace">?

  2. Can you ask your ASP.NET team friends if it is okay to do it like that - would be nice to have some confirmation - maybe it's a big no-no to change redirectMode and existingResponse in this way to be able to play nicely with SEO?!

  3. Can you add some clarification surrounding all that stuff (customErrors redirectMode="ResponseRewrite", customErrors redirectMode="ResponseRedirect", httpErrors errorMode="Custom" existingResponse="Replace", REMOVE customErrors COMPLETELY as someone suggested) after talking to your friends at Microsoft?

As I was saying; it would be supernice if we could make your answer more complete as this seem to be a fairly popular question with 54 000+ views.

Update: Unicorn answer does a 302 Found and a 200 OK and cannot be changed to only return 404 using a route. It has to be a physical file which is not very MVC:ish. So moving on to another solution. Too bad because this seemed to be the ultimate MVC:ish answer this far.

Where does Console.WriteLine go in ASP.NET?

System.Diagnostics.Debug.WriteLine(...); gets it into the Immediate Window in Visual Studio 2008.

Go to menu Debug -> Windows -> Immediate:

Enter image description here

AndroidStudio SDK directory does not exists

I think you should go to:

File ->Project Structure->SDK Location->

there select your sdk location.

Running MSBuild fails to read SDKToolsPath

I just had this error with a .sln file that was originally created in Visual Studio 2010 (and being built by Visual Studio 2010 and TFS 2010). I had modified the solution file to NOT build a project that was not supposed to be built in a particular configuration and visual studio changed the header of the solution file from:

Microsoft Visual Studio Solution File, Format Version 11.00
# Visual Studio 2010


Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio 14
VisualStudioVersion = 14.0.24720.0
MinimumVisualStudioVersion = 10.0.40219.1

Setting it back to the original 2010 version fixed my problem. I guess backwards compatibility in Visual Studio has still not been perfected.

Adding values to specific DataTable cells

If anyone is looking for an updated correct syntax for this as I was, try the following:

dg.Rows[0].Cells[6].Value = "test";

Cannot find firefox binary in PATH. Make sure firefox is installed. OS appears to be: VISTA

I got this error message while running tests in Visual Studio: Firefox simply wouldn't load and I got OP's error message.

I manually opened Firefox and found out that it needed to update itself (it did so before loading). Once finished I reran the test suite and Firefox showed up nicely, the tests were properly ran. If you get this error all of a sudden please try this answer before updating anything on your machine.

How to properly highlight selected item on RecyclerView?

Set private int selected_position = -1; to prevent from any item being selected on start.

 public void onBindViewHolder(final OrdersHolder holder, final int position) {
    final Order order = orders.get(position);
    if(selected_position == position){
        //changes background color of selected item in RecyclerView
    } else {
        //this updated an order property by status in DB
    holder.itemView.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            //status switch and DB update
            if (order.getProductStatus().equals("0")) {
                selected_position = position;
             } else {
                if (order.getProductStatus().equals("1")){
                    //calls for interface implementation in
                    //MainActivity which opens a new fragment with 
                    //selected item details 

Get an element by index in jQuery

$(...)[index]      // gives you the DOM element at index
$(...).get(index)  // gives you the DOM element at index
$(...).eq(index)   // gives you the jQuery object of element at index

DOM objects don't have css function, use the last...

$('ul li').eq(index).css({'background-color':'#343434'});


.get(index) Returns: Element

.eq(index) Returns: jQuery

vertical-align with Bootstrap 3

I ran into the same situation where I wanted to align a few div elements vertically in a row and found that Bootstrap classes col-xx-xx applies style to the div as float: left.

I had to apply the style on the div elements like style="Float:none" and all my div elements started vertically aligned. Here is the working example:

<div class="col-lg-4" style="float:none;">

JsFiddle Link

Just in case someone wants to read more about the float property:

W3Schools - Float

string.split - by multiple character delimiter

To show both string.Split and Regex usage:

string input = "abc][rfd][5][,][.";
string[] parts1 = input.Split(new string[] { "][" }, StringSplitOptions.None);
string[] parts2 = Regex.Split(input, @"\]\[");

How do I read image data from a URL in Python?

Manually wrapping in BytesIO is no longer needed since PIL >= 2.8.0. Just use

Adding on top of Vinícius's comment:

You should pass stream=True as noted


img =, stream=True).raw)

Call static method with reflection

As the documentation for MethodInfo.Invoke states, the first argument is ignored for static methods so you can just pass null.

foreach (var tempClass in macroClasses)
   // using reflection I will be able to run the method as:
   tempClass.GetMethod("Run").Invoke(null, null);

As the comment points out, you may want to ensure the method is static when calling GetMethod:

tempClass.GetMethod("Run", BindingFlags.Public | BindingFlags.Static).Invoke(null, null);

org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

* Thrown when a version number or timestamp check failed, indicating that the
* Session contained stale data (when using long transactions with versioning). 
* Also occurs if we try delete or update a row that does not exist.

if ( expectedRowCount > rowCount ) {
   throw new StaleStateException(           
  "Batch update returned unexpected row count from update [" + batchPosition +"]; actual row count: " + rowCount +"; expected: " + expectedRowCount);

<property name="show_sql">true</property> This should show you the SQL that is executed and causes the problem.

*The StaleStateException would be thrown only after we successfully deleted one object, and then tried to delete another. The reason for this is, while persisting the objects across sessions, objects must first be deleted from the Session before deleted. Otherwise, subsequent deletes will cause the StaleStateException to be thrown.


*The problem was that a table must have only one field that is primary key (I had a composite key and this is not a good idea, except for the many to many relation). I have solved using a new id table field auto incremental.

*It can be fix by using Hibernate session.update() -- you need to have the table/view's primary key equal your corresponding bean property (eg. id).


mysqli_fetch_array while loop columns

Try this :

   $i = 0;    
    while($row = mysqli_fetch_array($result)) {  

            $posts['post_id'] = $row[$i]['post_id'];
            $posts['post_title'] = $row[$i]['post_title'];
            $posts['type'] = $row[$i]['type'];
            $posts['author'] = $row[$i]['author'];  



Get only specific attributes with from Laravel Collection

I have now come up with an own solution to this:

1. Created a general function to extract specific attributes from arrays

The function below extract only specific attributes from an associative array, or an array of associative arrays (the last is what you get when doing $collection->toArray() in Laravel).

It can be used like this:

$data = array_extract( $collection->toArray(), ['id','url'] );

I am using the following functions:

function array_is_assoc( $array )
        return is_array( $array ) && array_diff_key( $array, array_keys(array_keys($array)) );

function array_extract( $array, $attributes )
    $data = [];

    if ( array_is_assoc( $array ) )
        foreach ( $attributes as $attribute )
            $data[ $attribute ] = $array[ $attribute ];
        foreach ( $array as $key => $values )
            $data[ $key ] = [];

            foreach ( $attributes as $attribute )
                $data[ $key ][ $attribute ] = $values[ $attribute ];

    return $data;   

This solution does not focus on performance implications on looping through the collections in large datasets.

2. Implement the above via a custom collection i Laravel

Since I would like to be able to simply do $collection->extract('id','url'); on any collection object, I have implemented a custom collection class.

First I created a general Model, which extends the Eloquent model, but uses a different collection class. All you models need to extend this custom model, and not the Eloquent Model then.

namespace App\Models;
use Illuminate\Database\Eloquent\Model as EloquentModel;
use Lib\Collection;
class Model extends EloquentModel
    public function newCollection(array $models = [])
        return new Collection( $models );

Secondly I created the following custom collection class:

namespace Lib;
use Illuminate\Support\Collection as EloquentCollection;
class Collection extends EloquentCollection
    public function extract()
        $attributes = func_get_args();
        return array_extract( $this->toArray(), $attributes );

Lastly, all models should then extend your custom model instead, like such:

namespace App\Models;
class Article extends Model

Now the functions from no. 1 above are neatly used by the collection to make the $collection->extract() method available.

Detect Android phone via Javascript / jQuery

js version, catches iPad too:

var is_mobile = /mobile|android/i.test (navigator.userAgent);

Selenium Webdriver submit() vs click()

I was a great fan of submit() but not anymore.

In the web page that I test, I enter username and password and click Login. When I invoked usernametextbox.submit(), password textbox is cleared (becomes empty) and login keeps failing.

After breaking my head for sometime, when I replaced usernametextbox.submit() with, it worked like a magic.

Running npm command within Visual Studio Code

All you need to do is to add args to the integrated terminal within 'User Settings' window.

Follow this steps below to do that:

  1. List item
  2. Go to 'User Settings'
  3. Search for setting named - ""
  4. Edit this setting by copying it to the right side.
  5. Add the following arg value = "/k nodevars.bat", e.g. "": ["/k nodevars.bat"],
  6. Make sure that the setting named "" is set to the value - "C:\Windows\system32\cmd.exe". If not then do that.
  7. Open new Terminal.

Good luck

How to tell bash that the line continues on the next line

The character is a backslash \

From the bash manual:

The backslash character ‘\’ may be used to remove any special meaning for the next character read and for line continuation.

Error:(23, 17) Failed to resolve: junit:junit:4.12

Look through for many answers but nothing works. Fortunately had found the easy solution. No need to comment junit4.12 or delete it. The problem is here:

- androidTestCompile files('libs/junit-4.12.jar')

This part shows us the path to look for the file in the library in your's project. No idea why but for some reason by the default it is empty. In my case the path is:


Sure you can delete this line in code build.grandle( but you may need it later. Here is the solution:

1 - download junit-4.12.jar or copy it from you Android Studio folder, normally it should be there. In my case, it was here:

C:\Program Files\Android\Android Studio\lib

to the directory mentioned above(to your project)

2 - delete & add

here you should re-enter the root to your junit-4.12.jar

3 - rebuild

4 - work hard

Python map object is not subscriptable

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:

Remove IE10's "clear field" X button on certain inputs?

To hide arrows and cross in a "time" input :

    -webkit-appearance: none;
    margin: 0;

Android: How to overlay a bitmap and draw over a bitmap?

If the purpose is to obtain a bitmap, this is very simple:

Canvas canvas = new Canvas();
canvas.drawBitmap(image2, new Matrix(), null);

In the end, image will contain the overlap of image and image2.

Echo a blank (empty) line to the console from a Windows batch file

Any of the below three options works for you:




For example:

@echo off
echo There will be a blank line below
echo Above line is blank
echo The above line is also blank.
echo The above line is also blank.

Add unique constraint to combination of two columns

Once you have removed your duplicate(s):

ALTER TABLE dbo.yourtablename
  ADD CONSTRAINT uq_yourtablename UNIQUE(column1, column2);


CREATE UNIQUE INDEX uq_yourtablename
  ON dbo.yourtablename(column1, column2);

Of course, it can often be better to check for this violation first, before just letting SQL Server try to insert the row and returning an exception (exceptions are expensive).

If you want to prevent exceptions from bubbling up to the application, without making changes to the application, you can use an INSTEAD OF trigger:

CREATE TRIGGER dbo.BlockDuplicatesYourTable
 ON dbo.YourTable

    INNER JOIN dbo.YourTable AS t
    ON i.column1 = t.column1
    AND i.column2 = t.column2
    INSERT dbo.YourTable(column1, column2, ...)
      SELECT column1, column2, ... FROM inserted;
    PRINT 'Did nothing.';

But if you don't tell the user they didn't perform the insert, they're going to wonder why the data isn't there and no exception was reported.

EDIT here is an example that does exactly what you're asking for, even using the same names as your question, and proves it. You should try it out before assuming the above ideas only treat one column or the other as opposed to the combination...

USE tempdb;

  Name NVARCHAR(32),
  Active BIT,
  PersonNumber INT

ALTER TABLE dbo.Person 
  ADD CONSTRAINT uq_Person UNIQUE(PersonNumber, Active);

-- succeeds:
INSERT dbo.Person(Name, Active, PersonNumber)
  VALUES(N'foo', 1, 22);

-- succeeds:
INSERT dbo.Person(Name, Active, PersonNumber)
  VALUES(N'foo', 0, 22);

-- fails:
INSERT dbo.Person(Name, Active, PersonNumber)
  VALUES(N'foo', 1, 22);

Data in the table after all of this:

ID   Name   Active PersonNumber
---- ------ ------ ------------
1    foo    1      22
2    foo    0      22

Error message on the last insert:

Msg 2627, Level 14, State 1, Line 3 Violation of UNIQUE KEY constraint 'uq_Person'. Cannot insert duplicate key in object 'dbo.Person'. The statement has been terminated.

How to make circular background using css?

Keep it simple:

    border-radius: 50%;
    width: 200px;
    height: 200px; 

Width and height can be anything, as long as they're equal

Compilation error: stray ‘\302’ in program etc

Change the name of the file.c to some other file423.c. it may be because of the name conflict between c files.

Python vs. Java performance (runtime speed)

There is no good answer as Python and Java are both specifications for which there are many different implementations. For example, CPython, IronPython, Jython, and PyPy are just a handful of Python implementations out there. For Java, there is the HotSpot VM, the Mac OS X Java VM, OpenJRE, etc. Jython generates Java bytecode, and so it would be using more-or-less the same underlying Java. CPython implements quite a handful of things directly in C, so it is very fast, but then again Java VMs also implement many functions in C. You would probably have to measure on a function-by-function basis and across a variety of interpreters and VMs in order to make any reasonable statement.

installing cPickle with python 3.5

cPickle comes with the standard library… in python 2.x. You are on python 3.x, so if you want cPickle, you can do this:

>>> import _pickle as cPickle

However, in 3.x, it's easier just to use pickle.

No need to install anything. If something requires cPickle in python 3.x, then that's probably a bug.