Programs & Examples On #Jcombobox

A JComboBox is a Java GUI object. It is a combination of a drop-down list and a single-line JTextField, allowing the user to either type a value directly into the control or choose from the list of existing options.

Execute an action when an item on the combobox is selected

The simple solution would be to use a ItemListener. When the state changes, you would simply check the currently selected item and set the text accordingly

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox06 {

    public static void main(String[] args) {
        new TestComboBox06();

    public TestComboBox06() {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {

                JFrame frame = new JFrame("Test");
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());


    public class TestPane extends JPanel {

        private JComboBox cb;
        private JTextField field;

        public TestPane() {
            cb = new JComboBox(new String[]{"Item 1", "Item 2"});
            field = new JTextField(12);



            cb.addItemListener(new ItemListener() {
                public void itemStateChanged(ItemEvent e) {
                    Object item = cb.getSelectedItem();
                    if ("Item 1".equals(item)) {
                    } else if ("Item 2".equals(item)) {



A better solution would be to create a custom object that represents the value to be displayed and the value associated with it...


Now I no longer have a 10 month chewing on my ankles, I updated the example to use a ListCellRenderer which is a more correct approach then been lazy and overriding toString

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox06 {

    public static void main(String[] args) {
        new TestComboBox06();

    public TestComboBox06() {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {

                JFrame frame = new JFrame("Test");
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());


    public class TestPane extends JPanel {

        private JComboBox cb;
        private JTextField field;

        public TestPane() {
            cb = new JComboBox(new Item[]{
                new Item("Item 1", "20"), 
                new Item("Item 2", "30")});
            cb.setRenderer(new ItemCelLRenderer());
            field = new JTextField(12);



            cb.addItemListener(new ItemListener() {
                public void itemStateChanged(ItemEvent e) {
                    Item item = (Item)cb.getSelectedItem();


    public class Item {
        private String value;
        private String text;

        public Item(String text, String value) {
            this.text = text;
            this.value = value;

        public String getText() {
            return text;

        public String getValue() {
            return value;


    public class ItemCelLRenderer extends DefaultListCellRenderer {

        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus); //To change body of generated methods, choose Tools | Templates.
            if (value instanceof Item) {
            return this;



How do I populate a JComboBox with an ArrayList?

Elegant way to fill combo box with an array list :

List<String> ls = new ArrayList<String>(); 
jComboBox.setModel(new DefaultComboBoxModel<String>(ls.toArray(new String[0])));

Adding items to a JComboBox

Method call setSelectedIndex("item_value"); doesn't work because setSelectedIndex use sequential index.

How to set selected index JComboBox by value

You should use model


JComboBox Selection Change Listener?

You may try these

 int selectedIndex = myComboBox.getSelectedIndex();


Object selectedObject = myComboBox.getSelectedItem();


String selectedValue = myComboBox.getSelectedValue().toString();

Rollback to an old Git commit in a public repo

The original poster states:

The best answer someone could give me was to use git revert X times until I reach the desired commit.

So let's say I want to revert back to a commit that's 20 commits old, I'd have to run it 20 times.

Is there an easier way to do this?

I can't use reset cause this repo is public.

It's not necessary to use git revert X times. git revert can accept a commit range as an argument, so you only need to use it once to revert a range of commits. For example, if you want to revert the last 20 commits:

git revert --no-edit HEAD~20..

The commit range HEAD~20.. is short for HEAD~20..HEAD, and means "start from the 20th parent of the HEAD commit, and revert all commits after it up to HEAD".

That will revert that last 20 commits, assuming that none of those are merge commits. If there are merge commits, then you cannot revert them all in one command, you'll need to revert them individually with

git revert -m 1 <merge-commit>

Note also that I've tested using a range with git revert using git version 1.9.0. If you're using an older version of git, using a range with git revert may or may not work.

In this case, git revert is preferred over git checkout.

Note that unlike this answer that says to use git checkout, git revert will actually remove any files that were added in any of the commits that you're reverting, which makes this the correct way to revert a range of revisions.


Cycles in family tree software

Relax your assertions.

Not by changing the rules, which are mostly likely very helpful to 99.9% of your customers in catching mistakes in entering their data.

Instead, change it from an error "can't add relationship" to a warning with an "add anyway".

Change status bar color with AppCompat ActionBarActivity

I don't think the status bar color has been implemented in AppCompat yet. These are the attributes which are available:

    <!-- ============= -->
    <!-- Color palette -->
    <!-- ============= -->

    <!-- The primary branding color for the app. By default, this is the color applied to the
         action bar background. -->
    <attr name="colorPrimary" format="color" />

    <!-- Dark variant of the primary branding color. By default, this is the color applied to
         the status bar (via statusBarColor) and navigation bar (via navigationBarColor). -->
    <attr name="colorPrimaryDark" format="color" />

    <!-- Bright complement to the primary branding color. By default, this is the color applied
         to framework controls (via colorControlActivated). -->
    <attr name="colorAccent" format="color" />

    <!-- The color applied to framework controls in their normal state. -->
    <attr name="colorControlNormal" format="color" />

    <!-- The color applied to framework controls in their activated (ex. checked) state. -->
    <attr name="colorControlActivated" format="color" />

    <!-- The color applied to framework control highlights (ex. ripples, list selectors). -->
    <attr name="colorControlHighlight" format="color" />

    <!-- The color applied to framework buttons in their normal state. -->
    <attr name="colorButtonNormal" format="color" />

    <!-- The color applied to framework switch thumbs in their normal state. -->
    <attr name="colorSwitchThumbNormal" format="color" />

(From \sdk\extras\android\support\v7\appcompat\res\values\attrs.xml)

vertical & horizontal lines in matplotlib

If you want to add a bounding box, use a rectangle:

ax = plt.gca()
r = matplotlib.patches.Rectangle((.5, .5), .25, .1, fill=False)

Rectangle doc

Jquery assiging class to th in a table

You had thead in your selector, but there is no thead in your table. Also you had your selectors backwards. As you mentioned above, you wanted to be adding the tr class to the th, not vice-versa (although your comment seems to contradict what you wrote up above).

$('tr th').each(function(index){     if($('tr td').eq(index).attr('class') != ''){         // get the class of the td         var tdClass = $('tr td').eq(index).attr('class');         // add it to this th         $(this).addClass(tdClass );     } }); 


How to remove part of a string before a ":" in javascript?

There is no need for jQuery here, regular JavaScript will do:

var str = "Abc: Lorem ipsum sit amet";
str = str.substring(str.indexOf(":") + 1);

Or, the .split() and .pop() version:

var str = "Abc: Lorem ipsum sit amet";
str = str.split(":").pop();

Or, the regex version (several variants of this):

var str = "Abc: Lorem ipsum sit amet";
str = /:(.+)/.exec(str)[1];

Java enum - why use toString instead of name

A practical example when name() and toString() make sense to be different is a pattern where single-valued enum is used to define a singleton. It looks surprisingly at first but makes a lot of sense:

enum SingletonComponent {

    /* ...behavior... */

    String toString() {
      return "SingletonComponent"; // better than default "INSTANCE"

In such case:

SingletonComponent myComponent = SingletonComponent.INSTANCE;
assertThat("INSTANCE"); // blah
assertThat(myComponent.toString()).isEqualTo("SingletonComponent"); // better

Declaring abstract method in TypeScript

The name property is marked as protected. This was added in TypeScript 1.3 and is now firmly established.

The makeSound method is marked as abstract, as is the class. You cannot directly instantiate an Animal now, because it is abstract. This is part of TypeScript 1.6, which is now officially live.

abstract class Animal {
    constructor(protected name: string) { }

    abstract makeSound(input : string) : string;

    move(meters) {
        alert( + " moved " + meters + "m.");

class Snake extends Animal {
    constructor(name: string) { super(name); }

    makeSound(input : string) : string {
        return "sssss"+input;

    move() {

The old way of mimicking an abstract method was to throw an error if anyone used it. You shouldn't need to do this any more once TypeScript 1.6 lands in your project:

class Animal {
    constructor(public name) { }
    makeSound(input : string) : string {
        throw new Error('This method is abstract');
    move(meters) {
        alert( + " moved " + meters + "m.");

class Snake extends Animal {
    constructor(name) { super(name); }
    makeSound(input : string) : string {
        return "sssss"+input;
    move() {

invalid use of non-static data member

The nested class doesn't know about the outer class, and protected doesn't help. You'll have to pass some actual reference to objects of the nested class type. You could store a foo*, but perhaps a reference to the integer is enough:

class Outer
    int n;

    class Inner
        int & a;
        Inner(int & b) : a(b) { }
        int & get() { return a; }

    // ...  for example:

    Inner inn;
    Outer() : inn(n) { }

Now you can instantiate inner classes like Inner i(n); and call i.get().

Apache: Restrict access to specific source IP inside virtual host

For Apache 2.4, you would use the Require IP directive. So to only allow machines from the network (range -

<VirtualHost *:80>
    <Location />
      Require ip

And if you just want the localhost machine to have access, then there's a special Require local directive.

The local provider allows access to the server if any of the following conditions is true:

  • the client address matches
  • the client address is ::1
  • both the client and the server address of the connection are the same

This allows a convenient way to match connections that originate from the local host:

<VirtualHost *:80>
    <Location />
      Require local

How to use UIPanGestureRecognizer to move object? iPhone/iPad

      UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
      [panRecognizer setMinimumNumberOfTouches:1];
      [panRecognizer setMaximumNumberOfTouches:1];
      [ViewMain addGestureRecognizer:panRecognizer];
      [panRecognizer release];
- (Void)handlePan:(UIPanGestureRecognizer *)recognizer

     CGPoint translation = [recognizer translationInView:self.view]; = CGPointMake( + translation.x, 
                            + translation.y);
     [recognizer setTranslation:CGPointMake(0, 0) inView:self.view];

     if (recognizer.state == UIGestureRecognizerStateEnded) {

         CGPoint velocity = [recognizer velocityInView:self.view];
         CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
         CGFloat slideMult = magnitude / 200;
         NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);

         float slideFactor = 0.1 * slideMult; // Increase for more of a slide
         CGPoint finalPoint = CGPointMake( + (velocity.x * slideFactor), 
                            + (velocity.y * slideFactor));
         finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);
         finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);

         [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
    = finalPoint;
         } completion:nil];



If Cell Starts with Text String... Formula

I know this is a really old post, but I found it in searching for a solution to the same problem. I don't want a nested if-statement, and Switch is apparently newer than the version of Excel I'm using. I figured out what was going wrong with my code, so I figured I'd share here in case it helps someone else.

I remembered that VLOOKUP requires the source table to be sorted alphabetically/numerically for it to work. I was initially trying to do this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"s","l","m"}, {-1,1,0})

and it started working when I did this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"l","m","s"}, {1,0,-1})

I was initially thinking the last value might turn out to be a default, so I wanted the zero at the last place. That doesn't seem to be the behavior anyway, so I just put the possible matches in order, and it worked.

Edit: As a final note, I see that the example in the original post has letters in alphabetical order, but I imagine the real use case might have been different if the error was happening and the letters A, B, and C were just examples.

Procedure or function !!! has too many arguments specified

Yet another cause of this error is when you are calling the stored procedure from code, and the parameter type in code does not match the type on the stored procedure.

R - Markdown avoiding package loading messages

My best solution on R Markdown was to create a code chunk only to load libraries and exclude everything in the chunk.

{r results='asis', echo=FALSE, include=FALSE,}
knitr::opts_chunk$set(echo = TRUE, warning=FALSE)
#formating tables

#data wrangling

#text processing

Joining three tables using MySQL

Don't join like that. It's a really really bad practice!!! It will slow down the performance in fetching with massive data. For example, if there were 100 rows in each tables, database server have to fetch 100x100x100 = 1000000 times. It had to fetch for 1 million times. To overcome that problem, join the first two table that can fetch result in minimum possible matching(It's up to your database schema). Use that result in Subquery and then join it with the third table and fetch it. For the very first join --> 100x100= 10000 times and suppose we get 5 matching result. And then we join the third table with the result --> 5x100 = 500. Total fetch = 10000+500 = 10200 times only. And thus, the performance went up!!!

How to implement a Boolean search with multiple columns in pandas

All the considerations made by @EdChum in 2014 are still valid, but the pandas.Dataframe.ix method is deprecated from the version 0.0.20 of pandas. Directly from the docs:

Warning: Starting in 0.20.0, the .ix indexer is deprecated, in favor of the more strict .iloc and .loc indexers.

In subsequent versions of pandas, this method has been replaced by new indexing methods pandas.Dataframe.loc and pandas.Dataframe.iloc.

If you want to learn more, in this post you can find comparisons between the methods mentioned above.

Ultimately, to date (and there does not seem to be any change in the upcoming versions of pandas from this point of view), the answer to this question is as follows:

foo = df.loc[(df['column1']==value) | (df['columns2'] == 'b') | (df['column3'] == 'c')]

How to store .pdf files into MySQL as BLOBs using PHP?

In regards to Gordon M's answer above, the 1st and 2nd parameter in mysqli_real_escape_string () call should be swapped for the newer php versions, according to:

Mongoimport of json file

This works with me when db with usrname and password

mongoimport --db YOUR_DB --collection MyCollection --file /your_path/my_json_file.json -u my_user -p my_pass

db without username password please remove -u my_user -p my_pass

My sample json

    "_id" : ObjectId("5d11c815eb946a412ecd677d"), 
    "empid" : NumberInt(1), 
    "name" : "Rahul"
    "_id" : ObjectId("5d11c815eb946a412ecd677e"), 
    "empid" : NumberInt(2), 
    "name" : "Rahul"

Convert JsonObject to String

There is an inbuilt method to convert a JSONObject to a String. Why don't you use that:

JSONObject json = new JSONObject();


Android Studio Rendering Problems : The following classes could not be found

I had to change my values/styles.xml to

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">

Before that change, it was without 'Base'.

(IntelliJ IDEA 2017.2.4)

How to compare two JSON have the same properties without order?

lodash will work, tested even for angular 5,

var remoteJSON = {"allowExternalMembers": "false", "whoCanJoin": 
var localJSON = {"whoCanJoin": "CAN_REQUEST_TO_JOIN", 
  "allowExternalMembers": "false"};

 if(_.isEqual(remoteJSON, localJSON)){

it works, for installation in angular, follow this

Magento: Set LIMIT on collection

The way to do was looking at the code in code/core/Mage/Catalog/Model/Resource/Category/Flat/Collection.php at line 380 in Magento 1.7.2 on the function setPage($pageNum, $pageSize)

 $collection = Mage::getModel('model')
     ->setCurPage(2) // 2nd page
     ->setPageSize(10); // 10 elements per pages

I hope this will help someone.

How to convert date to timestamp in PHP?

function date_to_stamp( $date, $slash_time = true, $timezone = 'Europe/London', $expression = "#^\d{2}([^\d]*)\d{2}([^\d]*)\d{4}$#is" ) {
    $return = false;
    $_timezone = date_default_timezone_get();
    date_default_timezone_set( $timezone );
    if( preg_match( $expression, $date, $matches ) )
        $return = date( "Y-m-d " . ( $slash_time ? '00:00:00' : "h:i:s" ), strtotime( str_replace( array($matches[1], $matches[2]), '-', $date ) . ' ' . date("h:i:s") ) );
    date_default_timezone_set( $_timezone );
    return $return;

// expression may need changing in relation to timezone
echo date_to_stamp('19/03/1986', false) . '<br />';
echo date_to_stamp('19**03**1986', false) . '<br />';
echo date_to_stamp('19.03.1986') . '<br />';
echo date_to_stamp('19.03.1986', false, 'Asia/Aden') . '<br />';
echo date('Y-m-d h:i:s') . '<br />';

//1986-03-19 02:37:30
//1986-03-19 02:37:30
//1986-03-19 00:00:00
//1986-03-19 05:37:30
//2012-02-12 02:37:30

How to set div width using ng-style

ngStyle accepts a map:

$scope.myStyle = {
    "width" : "900px",
    "background" : "red"


Create a pointer to two-dimensional array

To fully understand this, you must grasp the following concepts:

Arrays are not pointers!

First of all (And it's been preached enough), arrays are not pointers. Instead, in most uses, they 'decay' to the address to their first element, which can be assigned to a pointer:

int a[] = {1, 2, 3};

int *p = a; // p now points to a[0]

I assume it works this way so that the array's contents can be accessed without copying all of them. That's just a behavior of array types and is not meant to imply that they are same thing.

Multidimensional arrays

Multidimensional arrays are just a way to 'partition' memory in a way that the compiler/machine can understand and operate on.

For instance, int a[4][3][5] = an array containing 4*3*5 (60) 'chunks' of integer-sized memory.

The advantage over using int a[4][3][5] vs plain int b[60] is that they're now 'partitioned' (Easier to work with their 'chunks', if needed), and the program can now perform bound checking.

In fact, int a[4][3][5] is stored exactly like int b[60] in memory - The only difference is that the program now manages it as if they're separate entities of certain sizes (Specifically, four groups of three groups of five).

Keep in mind: Both int a[4][3][5] and int b[60] are the same in memory, and the only difference is how they're handled by the application/compiler

  {1, 2, 3, 4, 5}
  {6, 7, 8, 9, 10}
  {11, 12, 13, 14, 15}
  {16, 17, 18, 19, 20}
  {21, 22, 23, 24, 25}
  {26, 27, 28, 29, 30}
  {31, 32, 33, 34, 35}
  {36, 37, 38, 39, 40}
  {41, 42, 43, 44, 45}
  {46, 47, 48, 49, 50}
  {51, 52, 53, 54, 55}
  {56, 57, 58, 59, 60}

From this, you can clearly see that each "partition" is just an array that the program keeps track of.


Now, arrays are syntactically different from pointers. Specifically, this means the compiler/machine will treat them differently. This may seem like a no brainer, but take a look at this:

int a[3][3];

printf("%p %p", a, a[0]);

The above example prints the same memory address twice, like this:

0x7eb5a3b4 0x7eb5a3b4

However, only one can be assigned to a pointer so directly:

int *p1 = a[0]; // RIGHT !

int *p2 = a; // WRONG !

Why can't a be assigned to a pointer but a[0] can?

This, simply, is a consequence of multidimensional arrays, and I'll explain why:

At the level of 'a', we still see that we have another 'dimension' to look forward to. At the level of 'a[0]', however, we're already in the top dimension, so as far as the program is concerned we're just looking at a normal array.

You may be asking:

Why does it matter if the array is multidimensional in regards to making a pointer for it?

It's best to think this way:

A 'decay' from a multidimensional array is not just an address, but an address with partition data (AKA it still understands that its underlying data is made of other arrays), which consists of boundaries set by the array beyond the first dimension.

This 'partition' logic cannot exist within a pointer unless we specify it:

int a[4][5][95][8];

int (*p)[5][95][8];

p = a; // p = *a[0] // p = a+0

Otherwise, the meaning of the array's sorting properties are lost.

Also note the use of parenthesis around *p: int (*p)[5][95][8] - That's to specify that we're making a pointer with these bounds, not an array of pointers with these bounds: int *p[5][95][8]


Let's review:

  • Arrays decay to addresses if they have no other purpose in the used context
  • Multidimensional arrays are just arrays of arrays - Hence, the 'decayed' address will carry the burden of "I have sub dimensions"
  • Dimension data cannot exist in a pointer unless you give it to it.

In brief: multidimensional arrays decay to addresses that carry the ability to understand their contents.

Best Free Text Editor Supporting *More Than* 4GB Files?

f you just want to view a large file rather than edit it, there are a couple of freeware programs that read files a chunk at a time rather than trying to load the entire file in to memory. I use these when I need to read through large ( > 5 GB) files.

Large Text File Viewer by swiftgear

Big File Viewer by Team Walrus.

You'll have to find the link yourself for that last one because the I can only post a maximum of one hyperlink being a newbie.

How to convert an array of key-value tuples into an object

Update June 2020

ECMAScript 2021 brings Object.fromEntries which does exactly the requirement:

const array =    [ [ 'cardType', 'iDEBIT' ],
      [ 'txnAmount', '17.64' ],
      [ 'txnId', '20181' ],
      [ 'txnType', 'Purchase' ],
      [ 'txnDate', '2015/08/13 21:50:04' ],
      [ 'respCode', '0' ],
      [ 'isoCode', '0' ],
      [ 'authCode', '' ],
      [ 'acquirerInvoice', '0' ],
      [ 'message', '' ],
      [ 'isComplete', 'true' ],
      [ 'isTimeout', 'false' ] ];
const obj = Object.fromEntries(array);

This will do it:

const array =    [ [ 'cardType', 'iDEBIT' ],
      [ 'txnAmount', '17.64' ],
      [ 'txnId', '20181' ],
      [ 'txnType', 'Purchase' ],
      [ 'txnDate', '2015/08/13 21:50:04' ],
      [ 'respCode', '0' ],
      [ 'isoCode', '0' ],
      [ 'authCode', '' ],
      [ 'acquirerInvoice', '0' ],
      [ 'message', '' ],
      [ 'isComplete', 'true' ],
      [ 'isTimeout', 'false' ] ];
var obj = {};
    obj[data[0]] = data[1]

How to determine whether code is running in DEBUG / RELEASE build?

Just one more idea to detect:


#import <Foundation/Foundation.h>

@interface DebugMode: NSObject
    +(BOOL) isDebug;


#import "DebugMode.h"

@implementation DebugMode
+(BOOL) isDebug {
#ifdef DEBUG
    return true;
    return false;

add into header bridge file:

#include "DebugMode.h"



It is not needed to write something inside project properties swift flags.

SQL Server database backup restore on lower version

Go to Task->Generate Scripts...

In Advanced in "Types of data for script" select "Schema and data" and try to run this script in your lower version.

How can I resize an image dynamically with CSS as the browser width/height changes?

2018 and later solution:

Using viewport-relative units should make your life way easier, given we have the image of a cat:


Now we want this cat inside our code, while respecting aspect ratios:

img {_x000D_
  width: 100%;_x000D_
  height: auto;_x000D_
<img src="" alt="cat">

So far not really interesting, but what if we would like to change the cats width to be the maximum of 50% of the viewport?

img {_x000D_
  width: 100%;_x000D_
  height: auto;_x000D_
  /* Magic! */_x000D_
  max-width: 50vw;_x000D_
<img src="" alt="cat">

The same image, but now restricted to a maximum width of 50vw vw (=viewport width) means the image will be X width of the viewport, depending on the digit provided. This also works for height:

img {_x000D_
  width: auto;_x000D_
  height: 100%;_x000D_
  max-height: 20vh;_x000D_
<img src="" alt="cat">

This restricts the height of the image to a maximum of 20% of the viewport.

Dump all tables in CSV format using 'mysqldump'

It looks like others had this problem also, and there is a simple Python script now, for converting output of mysqldump into CSV files.

mysqldump -u username -p --host=rdshostname database table | python > table.csv

sklearn plot confusion matrix with labels

As hinted in this question, you have to "open" the lower-level artist API, by storing the figure and axis objects passed by the matplotlib functions you call (the fig, ax and cax variables below). You can then replace the default x- and y-axis ticks using set_xticklabels/set_yticklabels:

from sklearn.metrics import confusion_matrix

labels = ['business', 'health']
cm = confusion_matrix(y_test, pred, labels)
fig = plt.figure()
ax = fig.add_subplot(111)
cax = ax.matshow(cm)
plt.title('Confusion matrix of the classifier')
ax.set_xticklabels([''] + labels)
ax.set_yticklabels([''] + labels)

Note that I passed the labels list to the confusion_matrix function to make sure it's properly sorted, matching the ticks.

This results in the following figure:

enter image description here

Add a list item through javascript

The above answer was helpful for me, but it might be useful (or best practice) to add the name on submit, as I wound up doing. Hopefully this will be helpful to someone. CodePen Sample

    <form id="formAddName">
        <legend>Add Name </legend>
            <label for="firstName">First Name</label>
            <input type="text" id="firstName" name="firstName" />


      <ol id="demo"></ol>

    var list = document.getElementById('demo');
    var entry = document.getElementById('formAddName');
    entry.onsubmit = function(evt) {
    var firstName = document.getElementById('firstName').value;
    var entry = document.createElement('li');

Link to reload current page

Completely idempotent url that preserves path, parameters, and anchor.

 <a href="javascript:"> click me </a>

it only uses a little tiny bit of JS.

EDIT: this does not reload the page. It is a link that does nothing.

How can I convert an HTML element to a canvas element?

There is a library that try to do what you say.

See this examples and get the code

Reads the DOM, from the html and render it to a canvas, fail on some, but in general works.

How can I plot a confusion matrix?

IF you want more data in you confusion matrix, including "totals column" and "totals line", and percents (%) in each cell, like matlab default (see image below)

enter image description here

including the Heatmap and other options...

You should have fun with the module above, shared in the github ; )

This module can do your task easily and produces the output above with a lot of params to customize your CM: enter image description here

How to top, left justify text in a <td> cell that spans multiple rows

td[rowspan] {
  vertical-align: top;
  text-align: left;

See: CSS attribute selectors.

Leading zeros for Int in Swift

Swift 4* and above you can try this also:

func leftPadding(valueString: String, toLength: Int, withPad: String = " ") -> String {
        guard toLength > valueString.count else { return valueString }
        let padding = String(repeating: withPad, count: toLength - valueString.count)
        return padding + valueString

call the function:

leftPadding(valueString: "12", toLength: 5, withPad: "0")

Output: "00012"

How to convert a list of numbers to jsonarray in Python

Use the json module to produce JSON output:

import json

with open(outputfilename, 'wb') as outfile:
    json.dump(row, outfile)

This writes the JSON result directly to the file (replacing any previous content if the file already existed).

If you need the JSON result string in Python itself, use json.dumps() (added s, for 'string'):

json_string = json.dumps(row)

The L is just Python syntax for a long integer value; the json library knows how to handle those values, no L will be written.

Demo string output:

>>> import json
>>> row = [1L,[0.1,0.2],[[1234L,1],[134L,2]]]
>>> json.dumps(row)
'[1, [0.1, 0.2], [[1234, 1], [134, 2]]]'

Creating composite primary key in SQL Server

it simple, select columns want to insert primary key and click on Key icon on header and save tablesql composite key

happy coding..,

How to change the icon of an Android app in Eclipse?

Icon creation wizard

  • Select your project
  • Ctrl+n
  • Android Icon Set

Best way to check if a Data Table has a null value in it

DataTable dt = new DataTable();
foreach (DataRow dr in dt.Rows)
    if (dr["Column_Name"] == DBNull.Value)
        //Do something
        //Do something

Convert normal Java Array or ArrayList to Json Array in android

example key = "Name" value = "Xavier" and the value depends on number of array you pass in

      JSONArray jArry=new JSONArray();
      for (int i=0;i<3;i++)
       JSONObject jObjd=new JSONObject();
       jObjd.put("key", value);
       jObjd.put("key", value);
      Log.e("Test", jArry.toString());
 catch(JSONException ex)


Python locale error: unsupported locale setting

More permanent solution would be to fill the missing values, in the output shown by command: locale

Output from locale is:

 $ locale

To Fill the missing values edit ~/.bashrc :

 $ vim ~/.bashrc

Add the following lines after the above command (suppose you want en_US.UTF-8 to be your language):

export LANGUAGE="en_US.UTF-8"
export LC_ALL="en_US.UTF-8"

If this file is ReadOnly you would be needing to follow the steps mentioned by The GeekyBoy. The answer given by Dr Beco in Superuser has details relating to saving readonly files.

After saving the file do:

$ source ~/.bashrc

Now you wont be facing the same problem anymore.

How to return a value from pthread threads in C?

I think you have to store the number on heap. The int ret variable was on stack and was destructed at the end of execution of function myThread.

void *myThread()
       int *ret = malloc(sizeof(int));
       if (ret == NULL) {
           // ...
       *ret = 42;

Don't forget to free it when you don't need it :)

Another solution is to return the number as value of the pointer, like Neil Butterworth suggests.

Numpy array dimensions


By convention, in Python world, the shortcut for numpy is np, so:

In [1]: import numpy as np

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


In Numpy, dimension, axis/axes, shape are related and sometimes similar concepts:


In Mathematics/Physics, dimension or dimensionality is informally defined as the minimum number of coordinates needed to specify any point within a space. But in Numpy, according to the numpy doc, it's the same as axis/axes:

In Numpy dimensions are called axes. The number of axes is rank.

In [3]: a.ndim  # num of dimensions/axes, *Mathematics definition of dimension*
Out[3]: 2


the nth coordinate to index an array in Numpy. And multidimensional arrays can have one index per axis.

In [4]: a[1,0]  # to index `a`, we specific 1 at the first axis and 0 at the second axis.
Out[4]: 3  # which results in 3 (locate at the row 1 and column 0, 0-based index)


describes how many data (or the range) along each available axis.

In [5]: a.shape
Out[5]: (2, 2)  # both the first and second axis have 2 (columns/rows/pages/blocks/...) data

Cannot uninstall angular-cli

Step 1:

npm uninstall -g angular-cli

Step 2:

npm cache clean

Step 3:

npm cache verify

Step 4:

npm cache verify --force

Note: You can also delete by the following the paths

C:\Users"System_name"\AppData\Roaming\npm and



Step 5:

npm install -g @angular/cli@latest

How to create a notification with NotificationCompat.Builder?

You can try this code this works fine for me:

    NotificationCompat.Builder mBuilder= new NotificationCompat.Builder(this);

    Intent i = new Intent(noti.this, Xyz_activtiy.class);
    PendingIntent pendingIntent= PendingIntent.getActivity(this,0,i,0);

    mBuilder.setContentTitle("New notification title");
    mBuilder.setContentText("Notification text");

    NotificationManager notificationManager= (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

Call ASP.NET function from JavaScript?

You can use PageMethods.Your C# method Name in order to access C# methods or VB.NET methods into JavaScript.

How can I solve "Non-static method xxx:xxx() should not be called statically in PHP 5.4?

Disabling the alert message is not a way to solve the problem. Despite the PHP core is continue to work it makes a dangerous assumptions and actions.

Never ignore the error where PHP should make an assumptions of something!!!!

If the class organized as a singleton you can always use function getInstance() and then use getData()


$classObj = MyClass::getInstance();

If the class is not a singleton, use

 $classObj = new MyClass();

Adding new line of data to TextBox

C# - serialData is ReceivedEventHandler in TextBox.

SerialPort sData = sender as SerialPort;
string recvData = sData.ReadLine();

serialData.Invoke(new Action(() => serialData.Text = String.Concat(recvData)));

Now Visual Studio drops my lines. TextBox, of course, had all the correct options on.


Serial.( '\n' );  //carriage return

add new element in laravel collection object

As mentioned above if you wish to as a new element your queried collection you can use:

    $items = DB::select(DB::raw('SELECT * FROM items WHERE = '.$id.'  ;'));
    foreach($items as $item){
        $product = DB::select(DB::raw(' select * from product
               where product_id = '. $id.';' ));

        // or 
        // $items->put('products', $product);

but if you wish to add new element to each queried element you need to do like:

    $items = DB::select(DB::raw('SELECT * FROM items WHERE = '.$id.'  ;'));
    foreach($items as $item){
           $product = DB::select(DB::raw(' select * from product
                 where product_id = '. $id.';' ));

          $item->add_whatever_element_you_want = $product;

add_whatever_element_you_want can be whatever you wish that your element is named (like product for example).

Writing html form data to a txt file without the use of a webserver

I know this is old, but it's the first example of saving form data to a txt file I found in a quick search. So I've made a couple edits to the above code that makes it work more smoothly. It's now easier to add more fields, including the radio button as @user6573234 requested.

<!DOCTYPE html>
form * {
  display: block;
  margin: 10px;
<script language="Javascript" >
function download() {
  var filename = window.document.myform.docname.value;
  var name =;
  var text =  window.document.myform.text.value;
  var problem =  window.document.myform.problem.value;
  var pom = document.createElement('a');
  pom.setAttribute('href', 'data:text/plain;charset=utf-8,' + 
    "Your Name: " + encodeURIComponent(name) + "\n\n" +
    "Problem: " + encodeURIComponent(problem) + "\n\n" +

  pom.setAttribute('download', filename); = 'none';

<form name="myform" method="post" >
  <input type="text" id="docname" value="test.txt" />
  <input type="text" id="name" placeholder="Your Name" />
  <div style="display:unblock">
    Option 1 <input type="radio" value="Option 1" onclick="getElementById('problem').value=this.value; getElementById('problem').show()" style="display:inline" />
    Option 2 <input type="radio" value="Option 2" onclick="getElementById('problem').value=this.value;" style="display:inline" />
    <input type="text" id="problem" />
  <textarea rows=3 cols=50 id="text" />Please type in this box. 
When you click the Download button, the contents of this box will be downloaded to your machine at the location you specify. Pretty nifty. </textarea>
  <input id="download_btn" type="submit" class="btn" style="width: 125px" onClick="download();" />

Checking if a number is an Integer in Java

 int x = 3;

 if(ceil(x) == x) {

  System.out.println("x is an integer");

 } else {

  System.out.println("x is not an integer");


Does `anaconda` create a separate PYTHONPATH variable for each new environment?

Anaconda does not use the PYTHONPATH. One should however note that if the PYTHONPATH is set it could be used to load a library that is not in the anaconda environment. That is why before activating an environment it might be good to do a


For instance this PYTHONPATH points to an incorrect pandas lib:

export PYTHONPATH=/home/john/share/usr/anaconda/lib/python
source activate anaconda-2.7
>>>> import pandas as pd
/home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/ undefined symbol: PyUnicodeUCS2_DecodeUTF8
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/", line 6, in <module>
    from . import hashtable, tslib, lib
ImportError: /home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/ undefined symbol: PyUnicodeUCS2_DecodeUTF8

unsetting the PYTHONPATH prevents the wrong pandas lib from being loaded:

source activate anaconda-2.7
>>>> import pandas as pd

How do I keep Python print from adding newlines or spaces?

import sys
for i in range(0,len(a)):

Cross Browser Flash Detection in Javascript

Detecting and embedding Flash within a web document is a surprisingly difficult task.

I was very disappointed with the quality and non-standards compliant markup generated from both SWFObject and Adobe's solutions. Additionally, my testing found Adobe's auto updater to be inconsistent and unreliable.

The JavaScript Flash Detection Library (Flash Detect) and JavaScript Flash HTML Generator Library (Flash TML) are a legible, maintainable and standards compliant markup solution.

-"Luke read the source!"

How to check which locks are held on a table

I use a Dynamic Management View (DMV) to capture locks as well as the object_id or partition_id of the item that is locked.

(MUST switch to the Database you want to observe to get object_id)

     WT.blocking_session_id, AS [object name],
     O.type_desc AS [object descr],
     P.partition_id AS [partition id],
     P.rows AS [partition/page rows],
     AU.type_desc AS [index descr],
     AU.container_id AS [index/page container_id]
FROM sys.dm_tran_locks AS TL
INNER JOIN sys.dm_os_waiting_tasks AS WT 
 ON TL.lock_owner_address = WT.resource_address
LEFT OUTER JOIN sys.objects AS O 
 ON O.object_id = TL.resource_associated_entity_id
LEFT OUTER JOIN sys.partitions AS P 
 ON P.hobt_id = TL.resource_associated_entity_id
LEFT OUTER JOIN sys.allocation_units AS AU 
 ON AU.allocation_unit_id = TL.resource_associated_entity_id;

Internet Explorer cache location

The location of the Temporary Internet Files folder depends on your version of Windows and whether or not you are using user profiles.

  • If you have Windows Vista, then temporary Internet files are in these locations (note that on your PC they can be on some drive other than C):

    C:\Users[username]\AppData\Local\Microsoft\Windows\Temporary Internet Files\ C:\Users[username]\AppData\Local\Microsoft\Windows\Temporary Internet Files\Low\

    Note that you will have to change the settings of Windows Explorer to show all kinds of files (including the protected system files) in order to access these folders.

  • If you have Windows XP or Windows 2000, then temporary Internet files are in this location (note that on your PC they can be on some drive other than C):

    C:\Documents and Settings[username]\Local Settings\Temporary Internet Files\

    If you have only one user account, then replace [username] with Administrator to get the path of the Temporary Internet Files folder.

  • If you have Windows Me, Windows 98, Windows NT or Windows 95, then index.dat files are in these locations:

    C:\Windows\Temporary Internet Files\
    C:\Windows\Profiles[username]\Temporary Internet Files\

    Note that on your computer, the Windows directory may not be C:\Windows but some other directory. If you don't have a Profiles directory in your Windows directory, don't worry — this just means that you are not using user profiles.

Programmatically scroll to a specific position in an Android ListView

If someone looking for a similar functionality like Gmail app,

The Listview scroll will be positioned to top by default. Thanks for the hint. amalBit. Just subtract it. That's it.

 Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        public void run() {
            int h1 = mDrawerList.getHeight();
            int h2 = header.getHeight();
    }, 1000);

How do I vertical center text next to an image in html/css?

I recommend using tables with <td valign="middle"> (as inkedmn mentioned, it works in all browsers), but if you're wrapping with a link, here's how to do it (works in ugly old browsers too, like Opera 9):

<a href="/" style="display: block; vertical-align: middle;">
    <img src="/logo.png" style="vertical-align: middle;"/>
    <span style="vertical-align: middle;">Sample text</span>

Loop timer in JavaScript

It should be:

function moveItem() {
  jQuery(".stripTransmitter ul li a").trigger('click');

setInterval(f, t) calls the the argument function, f, once every t milliseconds.

How to resume Fragment from BackStack if exists

Step 1: Implement an interface with your activity class

public class AuthenticatedMainActivity extends Activity implements FragmentManager.OnBackStackChangedListener{

    protected void onCreate(Bundle savedInstanceState) {
        FragmentManager fragmentManager = getFragmentManager();           
        fragmentManager.beginTransaction().add(,fragment, "First").addToBackStack(null).commit();

    private void switchFragment(Fragment fragment){            
      FragmentManager fragmentManager = getFragmentManager();
        .replace(, fragment).addToBackStack("Tag").commit();

    public void onBackStackChanged() {
    FragmentManager fragmentManager = getFragmentManager();

    System.out.println("@Class: SummaryUser : onBackStackChanged " 
            + fragmentManager.getBackStackEntryCount());

    int count = fragmentManager.getBackStackEntryCount();

    // when a fragment come from another the status will be zero
    if(count == 0){

        System.out.println("again loading user data");

        // reload the page if user saved the profile data


                    , "Please check your internet connection");

        }else {

  "Refreshing data..."); 


        // IMPORTANT: remove the current fragment from stack to avoid new instance

    }// end if

Step 2: When you call the another fragment add this method:

String backStateName = this.getClass().getName();

FragmentManager fragmentManager = getFragmentManager();

Fragment fragmentGraph = new GraphFragment();
Bundle bundle = new Bundle();
bundle.putString("graphTag",  view.getTag().toString());

.replace(, fragmentGraph)

python's re: return True if string contains regex pattern

You can do something like this:

Using search will return a SRE_match object, if it matches your search string.

>>> import re
>>> m ='ba[r|z|d]', 'bar')
>>> m
<_sre.SRE_Match object at 0x02027288>
>>> n ='ba[r|z|d]', 'bas')

If not, it will return None

Traceback (most recent call last):
  File "<pyshell#17>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

And just to print it to demonstrate again:

>>> print n

How do I implement a progress bar in C#?

The idea behind reporting progress with the background worker is through sending a 'percent completed' event. You are yourself responsible for determining somehow 'how much' work has been completed. Unfortunately this is often the most difficult part.

In your case, the bulk of the work is database-related. There is to my knowledge no way to get progress information from the DB directly. What you can try to do however, is split up the work dynamically. E.g., if you need to read a lot of data, a naive way to implement this could be.

  • Determine how many rows are to be retrieved (SELECT COUNT(*) FROM ...)
  • Divide the actual reading in smaller chunks, reporting progress every time one chunk is completed:

    for (int i = 0; i < count; i++)
        bgWorker.ReportProgress((100 * i) / count);
        // ... (read data for step i)

How to scroll UITableView to specific position

Use [tableView scrollToRowAtIndexPath:indexPath atScrollPosition:scrollPosition animated:YES]; Scrolls the receiver until a row identified by index path is at a particular location on the screen.



Scrolls the table view so that the selected row nearest to a specified position in the table view is at that position.

HTML5 Video autoplay on iPhone

I had a similar problem and I tried multiple solution. I solved it implementing 2 considerations.

  1. Using dangerouslySetInnerHtml to embed the <video> code. For example:
<div dangerouslySetInnerHTML={{ __html: `
    <video class="video-js" playsinline autoplay loop muted>
        <source src="../video_path.mp4" type="video/mp4"/>
  1. Resizing the video weight. I noticed my iPhone does not autoplay videos over 3 megabytes. So I used an online compressor tool ( to go from 4mb to less than 500kb

Also, thanks to @boltcoder for his guide: Autoplay muted HTML5 video using React on mobile (Safari / iOS 10+)

How to add an element to Array and shift indexes?

Following code will insert the element at specified position and shift the existing elements to move next to new element.

public class InsertNumInArray {

public static void main(String[] args) {
    int[] inputArray = new int[] { 10, 20, 30, 40 };
    int inputArraylength = inputArray.length;
    int tempArrayLength = inputArraylength + 1;
    int num = 50, position = 2;
    int[] tempArray = new int[tempArrayLength];

    for (int i = 0; i < tempArrayLength; i++) {
        if (i != position && i < position)
            tempArray[i] = inputArray[i];
        else if (i == position)
            tempArray[i] = num;
            tempArray[i] = inputArray[i-1];

      inputArray = tempArray;

    for (int number : inputArray) {
        System.out.println("Number is: " + number);

HttpClient - A task was cancelled?

Promoting @JobaDiniz's comment to an answer:

Do not do the obvious thing and dispose the HttpClient instance, even though the code "looks right":

async Task<HttpResponseMessage> Method() {
  using (var client = new HttpClient())
    return client.GetAsync(request);

The same happens with C#'s new RIAA syntax; slightly less obvious:

async Task<HttpResponseMessage> Method() {
  using var client = new HttpClient();
  return client.GetAsync(request);

Instead, cache a static instance of HttpClient for your app or library, and reuse it:

static HttpClient client = new HttpClient();

async Task<HttpResponseMessage> Method() {
  return client.GetAsync(request);

(The Async() request methods are all thread safe.)

Concatenating string and integer in python

format() method can be used to concatenate string and integer


How can I remove a key from a Python dictionary?

Specifically to answer "is there a one line way of doing this?"

if 'key' in my_dict: del my_dict['key']

...well, you asked ;-)

You should consider, though, that this way of deleting an object from a dict is not atomic—it is possible that 'key' may be in my_dict during the if statement, but may be deleted before del is executed, in which case del will fail with a KeyError. Given this, it would be safest to either use dict.pop or something along the lines of

    del my_dict['key']
except KeyError:

which, of course, is definitely not a one-liner.

How can I scroll a web page using selenium webdriver in python?

insert this line driver.execute_script("window.scrollBy(0,925)", "")

Circle drawing with SVG's arc path

Adobe Illustrator uses bezier curves like SVG, and for circles it creates four points. You can create a circle with two elliptical arc commands...but then for a circle in SVG I would use a <circle /> :)

How to keep the header static, always on top while scrolling?

In modern, supported browsers, you can simply do that in CSS with -

  position: sticky;
  top: 0;

Note: The HTML structure is important while using position: sticky, since it's make the element sticky relative to the parent. And the sticky positioning might not work with a single element made sticky within a parent.

Run the snippet below to check a sample implementation.

padding: 0;_x000D_
position: sticky;_x000D_
background: lightblue;_x000D_
text-align: center;_x000D_
content > div {_x000D_
height: 50px;_x000D_
This is my header_x000D_
<div>Some content 1</div>_x000D_
<div>Some content 2</div>_x000D_
<div>Some content 3</div>_x000D_
<div>Some content 4</div>_x000D_
<div>Some content 5</div>_x000D_
<div>Some content 6</div>_x000D_
<div>Some content 7</div>_x000D_
<div>Some content 8</div>_x000D_

How can I URL encode a string in Excel VBA?

For the sake of bringing this up to date, since Excel 2013 there is now a built-in way of encoding URLs using the worksheet function ENCODEURL.

To use it in your VBA code you just need to call

EncodedUrl = WorksheetFunction.EncodeUrl(InputString)


How can I render a list select box (dropdown) with bootstrap?

Bootstrap 3 uses the .form-control class to style form components.

<select class="form-control">
    <option value="one">One</option>
    <option value="two">Two</option>
    <option value="three">Three</option>
    <option value="four">Four</option>
    <option value="five">Five</option>

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

Since you are asking in the context of a facebook app, you might want to consider detecting this at the server when the initial request is made. Facebook will pass along a bunch of querystring data including the fb_sig_user key if it is called from an iframe.

Since you probably need to check and use this data anyway in your app, use it to determine the the appropriate context to render.

Test if remote TCP port is open from a shell script

With netcat you can check whether a port is open like this:

nc 80 < /dev/null

The return value of nc will be success if the TCP port was opened, and failure (typically the return code 1) if it could not make the TCP connection.

Some versions of nc will hang when you try this, because they do not close the sending half of their socket even after receiving the end-of-file from /dev/null. On my own Ubuntu laptop (18.04), the netcat-openbsd version of netcat that I have installed offers a workaround: the -N option is necessary to get an immediate result:

nc -N 80 < /dev/null

Turn a number into star rating display using jQuery and CSS

If you only have to support modern browsers, you can get away with:

  • No images;
  • Mostly static css;
  • Nearly no jQuery or Javascript;

You only need to convert the number to a class, e.g. class='stars-score-50'.

First a demo of "rendered" markup:

body { font-size: 18px; }_x000D_
.stars-container {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  color: transparent;_x000D_
.stars-container:before {_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  content: '?????';_x000D_
  color: lightgray;_x000D_
.stars-container:after {_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  content: '?????';_x000D_
  color: gold;_x000D_
  overflow: hidden;_x000D_
.stars-0:after { width: 0%; }_x000D_
.stars-10:after { width: 10%; }_x000D_
.stars-20:after { width: 20%; }_x000D_
.stars-30:after { width: 30%; }_x000D_
.stars-40:after { width: 40%; }_x000D_
.stars-50:after { width: 50%; }_x000D_
.stars-60:after { width: 60%; }_x000D_
.stars-70:after { width: 70%; }_x000D_
.stars-80:after { width: 80%; }_x000D_
.stars-90:after { width: 90%; }_x000D_
.stars-100:after { width: 100; }
Within block level elements:_x000D_
<div><span class="stars-container stars-0">?????</span></div>_x000D_
<div><span class="stars-container stars-10">?????</span></div>_x000D_
<div><span class="stars-container stars-20">?????</span></div>_x000D_
<div><span class="stars-container stars-30">?????</span></div>_x000D_
<div><span class="stars-container stars-40">?????</span></div>_x000D_
<div><span class="stars-container stars-50">?????</span></div>_x000D_
<div><span class="stars-container stars-60">?????</span></div>_x000D_
<div><span class="stars-container stars-70">?????</span></div>_x000D_
<div><span class="stars-container stars-80">?????</span></div>_x000D_
<div><span class="stars-container stars-90">?????</span></div>_x000D_
<div><span class="stars-container stars-100">?????</span></div>_x000D_
<p>Or use it in a sentence: <span class="stars-container stars-70">?????</span> (cool, huh?).</p>

Then a demo that uses a wee bit of code:

$(function() {_x000D_
  function addScore(score, $domElement) {_x000D_
    $("<span class='stars-container'>")_x000D_
      .addClass("stars-" + score.toString())_x000D_
  addScore(70, $("#fixture"));_x000D_
body { font-size: 18px; }_x000D_
.stars-container {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  color: transparent;_x000D_
.stars-container:before {_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  content: '?????';_x000D_
  color: lightgray;_x000D_
.stars-container:after {_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  content: '?????';_x000D_
  color: gold;_x000D_
  overflow: hidden;_x000D_
.stars-0:after { width: 0%; }_x000D_
.stars-10:after { width: 10%; }_x000D_
.stars-20:after { width: 20%; }_x000D_
.stars-30:after { width: 30%; }_x000D_
.stars-40:after { width: 40%; }_x000D_
.stars-50:after { width: 50%; }_x000D_
.stars-60:after { width: 60%; }_x000D_
.stars-70:after { width: 70%; }_x000D_
.stars-80:after { width: 80%; }_x000D_
.stars-90:after { width: 90%; }_x000D_
.stars-100:after { width: 100; }
<script src=""></script>_x000D_
Generated: <div id="fixture"></div>

The biggest downsides of this solution are:

  1. You need the stars inside the element to generate correct width;
  2. There's no semantic markup, e.g. you'd prefer the score as text inside the element;
  3. It only allows for as many scores as you'll have classes (because we can't use Javascript to set a precise width on a pseudo-element).

To fix this the solution above can be easily tweaked. The :before and :after bits need to become actual elements in the DOM (so we need some JS for that).

The latter is left as an excercise for the reader.

Php - Your PHP installation appears to be missing the MySQL extension which is required by WordPress

As few people shared to tick mark the checkbox for mysqli and mysqlind

but Hostgator (webhosting site) now does not give that option to select extension via the cpanel as that option is removed select PHP and now it gives the option for php manager

You can just select the Php version you want and not the extension.

Solution :- Called the hostgator , first time they said get in touch with your developer, ( i asked my brother and he downloaded the files locally and verified it was working fine on local system) <-- this was not needed though

Again called the hostgator and their backend team installed the missing extension and it was solved.

Below is the code which gives this error when it does not find the extension and you can find this line in load.php via ftp.

if ( ! extension_loaded( 'mysql' ) && ! extension_loaded( 'mysqli' ) && ! extension_loaded( 'mysqlnd' ) && ! file_exists( WP_CONTENT_DIR . '/db.php' ) ) {
    require_once ABSPATH . WPINC . '/functions.php';
    $args = array(
        'exit' => false,
        'code' => 'mysql_not_found',
        __( 'Your PHP installation appears to be missing the MySQL extension which is required by WordPress.' ),
        __( 'Requirements Not Met' ),
    exit( 1 );


How to import a JSON file in ECMAScript 6?

A simple workaround:


export default
  // my json here...


import config from '../config.js'

does not allow import of existing .json files, but does a job.

How to create a JSON object

Usually, you would do something like this:

$post_data = json_encode(array('item' => $post_data));

But, as it seems you want the output to be with "{}", you better make sure to force json_encode() to encode as object, by passing the JSON_FORCE_OBJECT constant.

$post_data = json_encode(array('item' => $post_data), JSON_FORCE_OBJECT);

"{}" brackets specify an object and "[]" are used for arrays according to JSON specification.

Call a REST API in PHP

Use Guzzle. It's a "PHP HTTP client that makes it easy to work with HTTP/1.1 and takes the pain out of consuming web services". Working with Guzzle is much easier than working with cURL.

Here's an example from the Web site:

$client = new GuzzleHttp\Client();
$res = $client->get('', [
    'auth' =>  ['user', 'pass']
echo $res->getStatusCode();           // 200
echo $res->getHeader('content-type'); // 'application/json; charset=utf8'
echo $res->getBody();                 // {"type":"User"...'
var_export($res->json());             // Outputs the JSON decoded data

HTML 5 Favicon - Support?

No, not all browsers support the sizes attribute:

Note that some platforms define specific sizes:

How to keep the console window open in Visual C++?

cin.get(), or system("PAUSE"). I haven't heard you can use return(0);

How to get the previous page URL using JavaScript?

You want in page A to know the URL of page B?

Or to know in page B the URL of page A?

In Page B: document.referrer if set. As already shown here: How to get the previous URL in JavaScript?

In page A you would need to read a cookie or local/sessionStorage you set in page B, assuming the same domains

Simple post to Web Api

It's been quite sometime since I asked this question. Now I understand it more clearly, I'm going to put a more complete answer to help others.

In Web API, it's very simple to remember how parameter binding is happening.

  • if you POST simple types, Web API tries to bind it from the URL
  • if you POST complex type, Web API tries to bind it from the body of the request (this uses a media-type formatter).

  • If you want to bind a complex type from the URL, you'll use [FromUri] in your action parameter. The limitation of this is down to how long your data going to be and if it exceeds the url character limit.

    public IHttpActionResult Put([FromUri] ViewModel data) { ... }

  • If you want to bind a simple type from the request body, you'll use [FromBody] in your action parameter.

    public IHttpActionResult Put([FromBody] string name) { ... }

as a side note, say you are making a PUT request (just a string) to update something. If you decide not to append it to the URL and pass as a complex type with just one property in the model, then the data parameter in jQuery ajax will look something like below. The object you pass to data parameter has only one property with empty property name.

var myName = 'ABC';
$.ajax({url:.., data: {'': myName}});

and your web api action will look something like below.

public IHttpActionResult Put([FromBody] string name){ ... }

This page explains it all.

Is background-color:none valid CSS?

The answer is no.


.class {
    background-color: none; /* do not do this */


.class {
    background-color: transparent;

background-color: transparent accomplishes the same thing what you wanted to do with background-color: none.

What is a mutex?

In C#, the common mutex used is the Monitor. The type is 'System.Threading.Monitor'. It may also be used implicitly via the 'lock(Object)' statement. One example of its use is when constructing a Singleton class.

private static readonly Object instanceLock = new Object();
private static MySingleton instance;
public static MySingleton Instance
        if(instance == null)
            instance = new MySingleton();
        return instance;

The lock statement using the private lock object creates a critical section. Requiring each thread to wait until the previous is finished. The first thread will enter the section and initialize the instance. The second thread will wait, get into the section, and get the initialized instance.

Any sort of synchronization of a static member may use the lock statement similarly.

Changing user agent on urllib2.urlopen

Setting the User-Agent from everyone's favorite Dive Into Python.

The short story: You can use Request.add_header to do this.

You can also pass the headers as a dictionary when creating the Request itself, as the docs note:

headers should be a dictionary, and will be treated as if add_header() was called with each key and value as arguments. This is often used to “spoof” the User-Agent header, which is used by a browser to identify itself – some HTTP servers only allow requests coming from common browsers as opposed to scripts. For example, Mozilla Firefox may identify itself as "Mozilla/5.0 (X11; U; Linux i686) Gecko/20071127 Firefox/", while urllib2‘s default user agent string is "Python-urllib/2.6" (on Python 2.6).

Turn a string into a valid filename?

This is the solution I ultimately used:

import unicodedata

validFilenameChars = "-_.() %s%s" % (string.ascii_letters, string.digits)

def removeDisallowedFilenameChars(filename):
    cleanedFilename = unicodedata.normalize('NFKD', filename).encode('ASCII', 'ignore')
    return ''.join(c for c in cleanedFilename if c in validFilenameChars)

The unicodedata.normalize call replaces accented characters with the unaccented equivalent, which is better than simply stripping them out. After that all disallowed characters are removed.

My solution doesn't prepend a known string to avoid possible disallowed filenames, because I know they can't occur given my particular filename format. A more general solution would need to do so.

How to Replace dot (.) in a string in Java

If you want to replace a simple string and you don't need the abilities of regular expressions, you can just use replace, not replaceAll.

replace replaces each matching substring but does not interpret its argument as a regular expression.

str = xpath.replace(".", "/*/");

Java: Enum parameter in method

Sure, you could use an enum. Would something like the following work?

enum Alignment {

private static String drawCellValue(int maxCellLength, String cellValue, Alignment alignment) { }

If you wanted to use a boolean, you could rename the align parameter to something like alignLeft. I agree that this implementation is not as clean, but if you don't anticipate a lot of changes and this is not a public interface, it might be a good choice.

Defining and using a variable in batch file

Consider also using SETX - it will set variable on user or machine (available for all users) level though the variable will be usable with the next opening of the cmd.exe ,so often it can be used together with SET :

::setting variable for the current user
if not defined My_Var (
  set "My_Var=My_Value"
  setx My_Var My_Value

::setting machine defined variable
if not defined Global_Var (
  set "Global_Var=Global_Value"
  SetX Global_Var Global_Value /m

You can also edit directly the registry values:

User Variables: HKEY_CURRENT_USER\Environment

System Variables: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

Which will allow to avoid some restrictions of SET and SETX like the variables containing = in their names.

When to use React setState callback

},() => {

Change Orientation of Bluestack : portrait/landscape mode

This works for me for BlueStacks 4:

  • Install "Rotation Control" app enter image description here
  • Enable it to appear onto taskbar; optionally with system start enter image description here
  • Whenever you want to rotate the screen, just pull down the task bar, and give it a go enter image description here

Difference between Constructor and ngOnInit

The Constructor is a default method of the class that is executed when the class is instantiated and ensures proper initialisation of fields in the class and its subclasses. Angular, or better Dependency Injector (DI), analyses the constructor parameters and when it creates a new instance by calling new MyClass() it tries to find providers that match the types of the constructor parameters, resolves them and passes them to the constructor like

new MyClass(someArg);

ngOnInit is a life cycle hook called by Angular to indicate that Angular is done creating the component.

We have to import OnInit like this in order to use it (actually implementing OnInit is not mandatory but considered good practice):

import { Component, OnInit } from '@angular/core';

then to make use of the method OnInit, we have to implement the class like this:

export class App implements OnInit {
  constructor() {
     // Called first time before the ngOnInit()

  ngOnInit() {
     // Called after the constructor and called  after the first ngOnChanges() 

Implement this interface to execute custom initialization logic after your directive's data-bound properties have been initialized. ngOnInit is called right after the directive's data-bound properties have been checked for the first time, and before any of its children have been checked. It is invoked only once when the directive is instantiated.

Mostly we use ngOnInit for all the initialization/declaration and avoid stuff to work in the constructor. The constructor should only be used to initialize class members but shouldn't do actual "work".

So you should use constructor() to setup Dependency Injection and not much else. ngOnInit() is better place to "start" - it's where/when components' bindings are resolved.

For more information refer here:

Anaconda site-packages

At least with Miniconda (I assume it's the same for Anaconda), within the environment folder, the packages are installed in a folder called \conda-meta.



If you install on the base environment, the location is:


MySQL IF ELSEIF in select query

IF() in MySQL is a ternary function, not a control structure -- if the condition in the first argument is true, it returns the second argument; otherwise, it returns the third argument. There is no corresponding ELSEIF() function or END IF keyword.

The closest equivalent to what you've got would be something like:

IF(qty_1<='23', price,
  IF('23'>qty_1 && qty_2<='23', price_2,
    IF('23'>qty_2 && qty_3<='23', price_3,
      IF('23'>qty_3, price_4, 1)

The conditions don't all make sense to me (it looks as though some of them may be inadvertently reversed?), but without knowing what exactly you're trying to accomplish, it's hard for me to fix that.

Difference between h:button and h:commandButton


The <h:button> generates a HTML <input type="button">. The generated element uses JavaScript to navigate to the page given by the attribute outcome, using a HTTP GET request.


<h:button value="GET button" outcome="otherpage" />

will generate

<input type="button" onclick="window.location.href='/contextpath/otherpage.xhtml'; return false;" value="GET button" />

Even though this ends up in a (bookmarkable) URL change in the browser address bar, this is not SEO-friendly. Searchbots won't follow the URL in the onclick. You'd better use a <h:outputLink> or <h:link> if SEO is important on the given URL. You could if necessary throw in some CSS on the generated HTML <a> element to make it to look like a button.

Do note that while you can put an EL expression referring a method in outcome attribute as below,

<h:button value="GET button" outcome="#{bean.getOutcome()}" />

it will not be invoked when you click the button. Instead, it is already invoked when the page containing the button is rendered for the sole purpose to obtain the navigation outcome to be embedded in the generated onclick code. If you ever attempted to use the action method syntax as in outcome="#{bean.action}", you would already be hinted by this mistake/misconception by facing a javax.el.ELException: Could not find property actionMethod in class com.example.Bean.

If you intend to invoke a method as result of a POST request, use <h:commandButton> instead, see below. Or if you intend to invoke a method as result of a GET request, head to Invoke JSF managed bean action on page load or if you also have GET request parameters via <f:param>, How do I process GET query string URL parameters in backing bean on page load?


The <h:commandButton> generates a HTML <input type="submit"> button which submits by default the parent <h:form> using HTTP POST method and invokes the actions attached to action, actionListener and/or <f:ajax listener>, if any. The <h:form> is required.


<h:form id="form">
    <h:commandButton id="button" value="POST button" action="otherpage" />

will generate

<form id="form" name="form" method="post" action="/contextpath/currentpage.xhtml" enctype="application/x-www-form-urlencoded">
    <input type="hidden" name="form" value="form" />
    <input type="submit" name="form:button" value="POST button" />
    <input type="hidden" name="javax.faces.ViewState" id="javax.faces.ViewState" value="...." autocomplete="off" />

Note that it thus submits to the current page (the form action URL will show up in the browser address bar). It will afterwards forward to the target page, without any change in the URL in the browser address bar. You could add ?faces-redirect=true parameter to the outcome value to trigger a redirect after POST (as per the Post-Redirect-Get pattern) so that the target URL becomes bookmarkable.

The <h:commandButton> is usually exclusively used to submit a POST form, not to perform page-to-page navigation. Normally, the action points to some business action, such as saving the form data in DB, which returns a String outcome.

<h:commandButton ... action="#{}" />


public String save() {
    // ...
    return "otherpage";

Returning null or void will bring you back to the same view. Returning an empty string also, but it would recreate any view scoped bean. These days, with modern JSF2 and <f:ajax>, more than often actions just return to the same view (thus, null or void) wherein the results are conditionally rendered by ajax.

public void save() {
    // ...

See also:

Gunicorn worker timeout error

On Google Cloud Just add --timeout 90 to entrypoint in app.yaml

entrypoint: gunicorn -b :$PORT main:app --timeout 90

How to add a border just on the top side of a UIView

I made some changes to Dan's answer so that I could add borders to multiple edges with one command:

infoView.addBorder(toEdges: [.left, .bottom, .right], color: borderColor, thickness: 1)

Here's the full code:

extension UIView {
    func addBorder(toEdges edges: UIRectEdge, color: UIColor, thickness: CGFloat) {

        func addBorder(toEdge edges: UIRectEdge, color: UIColor, thickness: CGFloat) {
            let border = CALayer()
            border.backgroundColor = color.cgColor

            switch edges {
            case .top:
                border.frame = CGRect(x: 0, y: 0, width: frame.width, height: thickness)
            case .bottom:
                border.frame = CGRect(x: 0, y: frame.height - thickness, width: frame.width, height: thickness)
            case .left:
                border.frame = CGRect(x: 0, y: 0, width: thickness, height: frame.height)
            case .right:
                border.frame = CGRect(x: frame.width - thickness, y: 0, width: thickness, height: frame.height)


        if edges.contains(.top) || edges.contains(.all) {
            addBorder(toEdge: .top, color: color, thickness: thickness)

        if edges.contains(.bottom) || edges.contains(.all) {
            addBorder(toEdge: .bottom, color: color, thickness: thickness)

        if edges.contains(.left) || edges.contains(.all) {
            addBorder(toEdge: .left, color: color, thickness: thickness)

        if edges.contains(.right) || edges.contains(.all) {
            addBorder(toEdge: .right, color: color, thickness: thickness)

Javascript : array.length returns undefined

It looks as though it's not an array but an arbitrary object. If you have control over the PHP serialization, you might be able to change that.

As raina77ow pointed out, one way to do this in PHP would be by replacing something like this:


with something like:


But don't ignore the other answers here about Object.keys. They should also accomplish what you want if you don't have the ability or the desire to change the serialization of your object.

Can a PDF file's print dialog be opened with Javascript?

Another solution:

<input type="button" value="Print" onclick="document.getElementById('PDFtoPrint').focus(); document.getElementById('PDFtoPrint').contentWindow.print();">

Summarizing count and conditional aggregate functions on the same factor

Assuming that your original dataset is similar to the one you created (i.e. with NA as character. You could specify na.strings while reading the data using read.table. But, I guess NAs would be detected automatically.

The price column is factor which needs to be converted to numeric class. When you use as.numeric, all the non-numeric elements (i.e. "NA", FALSE) gets coerced to NA) with a warning.

df %>%
     mutate(price=as.numeric(as.character(price))) %>%  
     group_by(company, year, product) %>%
               max.price=max(price, na.rm=TRUE))


I am using the same dataset (except the ... row) that was showed.

df = tbl_df(data.frame(company=c("Acme", "Meca", "Emca", "Acme", "Meca","Emca"),
 year=c("2011", "2010", "2009", "2011", "2010", "2013"), product=c("Wrench", "Hammer",
 "Sonic Screwdriver", "Fairy Dust", "Kindness", "Helping Hand"), price=c("5.67",
 "7.12", "12.99", "10.99", "NA",FALSE)))

Spring Boot REST API - request timeout?

In Spring properties files, you can't just specify a number for this property. You also need to specify a unit. So you can say spring.mvc.async.request-timeout=5000ms or spring.mvc.async.request-timeout=5s, both of which will give you a 5-second timeout.

How to join entries in a set into one string?

You have the join statement backwards try:

print ', '.join(set_3)

Find out if string ends with another string in C++

Use std::equal algorithm from <algorithms> with reverse iteration:

std::string LogExt = ".log";
if (std::equal(LogExt.rbegin(), LogExt.rend(), filename.rbegin())) {

How Should I Declare Foreign Key Relationships Using Code First Entity Framework (4.1) in MVC3?

If you have an Order class, adding a property that references another class in your model, for instance Customer should be enough to let EF know there's a relationship in there:

public class Order
    public int ID { get; set; }

    // Some other properties

    // Foreign key to customer
    public virtual Customer Customer { get; set; }

You can always set the FK relation explicitly:

public class Order
    public int ID { get; set; }

    // Some other properties

    // Foreign key to customer
    public string CustomerID { get; set; }
    public virtual Customer Customer { get; set; }

The ForeignKeyAttribute constructor takes a string as a parameter: if you place it on a foreign key property it represents the name of the associated navigation property. If you place it on the navigation property it represents the name of the associated foreign key.

What this means is, if you where to place the ForeignKeyAttribute on the Customer property, the attribute would take CustomerID in the constructor:

public string CustomerID { get; set; }
public virtual Customer Customer { get; set; }

EDIT based on Latest Code You get that error because of this line:

public Patient Patient { get; set; }

EF will look for a property called Parent to use it as the Foreign Key enforcer. You can do 2 things:

1) Remove the ForeignKeyAttribute and replace it with the RequiredAttribute to mark the relation as required:

public virtual Patient Patient { get; set; }

Decorating a property with the RequiredAttribute also has a nice side effect: The relation in the database is created with ON DELETE CASCADE.

I would also recommend making the property virtual to enable Lazy Loading.

2) Create a property called Parent that will serve as a Foreign Key. In that case it probably makes more sense to call it for instance ParentID (you'll need to change the name in the ForeignKeyAttribute as well):

public int ParentID { get; set; }

In my experience in this case though it works better to have it the other way around:

public int ParentID { get; set; }

public virtual Patient Patient { get; set; }

How do you sort a dictionary by value?

Sorting a SortedDictionary list to bind into a ListView control using VB.NET:

Dim MyDictionary As SortedDictionary(Of String, MyDictionaryEntry)

MyDictionaryListView.ItemsSource = MyDictionary.Values.OrderByDescending(Function(entry) entry.MyValue)

Public Class MyDictionaryEntry ' Need Property for GridViewColumn DisplayMemberBinding
    Public Property MyString As String
    Public Property MyValue As Integer
End Class


<ListView Name="MyDictionaryListView">
            <GridViewColumn DisplayMemberBinding="{Binding Path=MyString}" Header="MyStringColumnName"></GridViewColumn>
            <GridViewColumn DisplayMemberBinding="{Binding Path=MyValue}" Header="MyValueColumnName"></GridViewColumn>

CSS Auto hide elements after 5 seconds

Why not try fadeOut?

$(document).ready(function() {_x000D_
  $('#plsme').fadeOut(5000); // 5 seconds x 1000 milisec = 5000 milisec_x000D_
<script src=""></script>_x000D_
<div id='plsme'>Loading... Please Wait</div>

fadeOut (Javascript Pure):

How to make fadeOut effect with pure JavaScript

Get User Selected Range

You can loop through the Selection object to see what was selected. Here is a code snippet from Microsoft (

Sub Count_Selection()
    Dim cell As Object
    Dim count As Integer
    count = 0
    For Each cell In Selection
        count = count + 1
    Next cell
    MsgBox count & " item(s) selected"
End Sub

Add and remove attribute with jquery

Once you remove the ID "page_navigation" that element no longer has an ID and so cannot be found when you attempt to access it a second time.

The solution is to cache a reference to the element:

    // This reference remains available to the following functions
    // even when the ID is removed.
    var page_navigation = $("#page_navigation1");



Replace all whitespace characters

Actually it has been worked but

just try this.

take the value /\s/g into a string variable like

String a = /\s/g;

str = str.replaceAll(a,"X");

JQUERY: Uncaught Error: Syntax error, unrecognized expression

The "double quote" + 'single quote' combo is not needed

console.log( $('#'+d) ); // single quotes only
console.log( $("#"+d) ); // double quotes only

Your selector results like this, which is overkill with the quotes:

$('"#abc"') // -> it'll try to find  <div id='"#abc"'>

// In css, this would be the equivalent:
"#abc"{ /* Wrong */ } // instead of:
#abc{ /* Right */ }

Range of values in C Int and Long 32 - 64 bits

In fact, unsigned int on most modern processors (ARM, Intel/AMD, Alpha, SPARC, Itanium ,PowerPC) will have a range of 0 to 2^32 - 1 which is 4,294,967,295 = 0xffffffff because int (both signed and unsigned) will be 32 bits long and the largest one is as stated.

(unsigned short will have maximal value 2^16 - 1 = 65,535 )

(unsigned) long long int will have a length of 64 bits (long int will be enough under most 64 bit Linuxes, etc, but the standard promises 64 bits for long long int). Hence these have the range 0 to 2^64 - 1 = 18446744073709551615

Python string class like StringBuilder in C#?

Using method 5 from above (The Pseudo File) we can get very good perf and flexibility

from cStringIO import StringIO

class StringBuilder:
     _file_str = None

     def __init__(self):
         self._file_str = StringIO()

     def Append(self, str):

     def __str__(self):
         return self._file_str.getvalue()

now using it

sb = StringBuilder()


print sb

What is a clean, Pythonic way to have multiple constructors in Python?

Use num_holes=None as a default, instead. Then check for whether num_holes is None, and if so, randomize. That's what I generally see, anyway.

More radically different construction methods may warrant a classmethod that returns an instance of cls.

Hiding table data using <div style="display:none">

Wrap the sections you want to hide in their own tbody and dynamically show/hide that.

Convert a SQL query result table to an HTML table for email

Here is one way to do it from an article titled "Format query output into an HTML table - the easy way [archive]". You would need to substitute the details of your own query for the ones in this example, which gets a list of tables and a row count.

declare @body varchar(max)

set @body = cast( (
select td = dbtable + '</td><td>' + cast( entities as varchar(30) ) + '</td><td>' + cast( rows as varchar(30) )
from (
      select dbtable  = object_name( object_id ),
             entities = count( distinct name ),
             rows     = count( * )
      from sys.columns
      group by object_name( object_id )
      ) as d
for xml path( 'tr' ), type ) as varchar(max) )

set @body = '<table cellpadding="2" cellspacing="2" border="1">'
          + '<tr><th>Database Table</th><th>Entity Count</th><th>Total Rows</th></tr>'
          + replace( replace( @body, '&lt;', '<' ), '&gt;', '>' )
          + '</table>'

print @body

Once you have @body, you can then use whatever email mechanism you want.

Node.js - use of module.exports as a constructor

The example code is:

in main

square(width,function (data)

using the following may works

exports.square = function(width,callback)
     var aa = new Object();
     callback(aa.squareVal = width * width);    

latex large division sign in a math formula

Another option is to use \dfrac instead of \frac, which makes the whole fraction larger and hence more readable.

And no, I don't know if there is an option to get something in between \frac and \dfrac, sorry.

How can I check if a checkbox is checked?

Try This

<script type="text/javascript">
window.onload = function () {
    var input = document.querySelector('input[type=checkbox]');

    function check() {
        if (input.checked) {
        } else {
            alert("You didn't check it.");
    input.onchange = check;

Remove IE10's "clear field" X button on certain inputs?

I would apply this rule to all input fields of type text, so it doesn't need to be duplicated later:

input[type=text]::-ms-clear { display: none; }

One can even get less specific by using just:

::-ms-clear { display: none; }

I have used the later even before adding this answer, but thought that most people would prefer to be more specific than that. Both solutions work fine.

ng-options with simple array init

<select ng-model="option" ng-options="o for o in options">

$scope.option will be equal to 'var1' after change, even you see value="0" in generated html


How to use enums as flags in C++?

I found myself asking the same question and came up with a generic C++11 based solution, similar to soru's:

template <typename TENUM>
class FlagSet {

    using TUNDER = typename std::underlying_type<TENUM>::type;
    std::bitset<std::numeric_limits<TUNDER>::max()> m_flags;

    FlagSet() = default;

    template <typename... ARGS>
    FlagSet(TENUM f, ARGS... args) : FlagSet(args...)
    FlagSet& set(TENUM f)
        return *this;
    bool test(TENUM f)
        return m_flags.test(static_cast<TUNDER>(f));
    FlagSet& operator|=(TENUM f)
        return set(f);

The interface can be improved to taste. Then it can be used like so:

FlagSet<Flags> flags{Flags::FLAG_A, Flags::FLAG_C};
flags |= Flags::FLAG_D;

how to redirect to home page


var re = /^https?:\/\/[^/]+/i;
window.location.href = re.exec(window.location.href)[0];

is what you're looking for?

How to prevent the "Confirm Form Resubmission" dialog?

I was having this problem and added this JavaScript to the bottom of my page (read it at and it seemed to work. It seems much simpler a solution. Any drawbacks?

if ( window.history.replaceState ) {
  window.history.replaceState( null, null, window.location.href );



Laravel: Validation unique on update

$rules = [
    "email" => "email|unique:users, email, '.$id.', user_id"

In Illuminate\Validation\Rules\Unique;

Unique validation will parse string validation to Rule object

Unique validation has pattern: unique:%s,%s,%s,%s,%s'

Corresponding with: table name, column, ignore, id column, format wheres

 * Convert the rule to a validation string.
 * @return string
public function __toString()
    return rtrim(sprintf('unique:%s,%s,%s,%s,%s',
        $this->ignore ?: 'NULL',
    ), ',');

Loop through an array of strings in Bash?

listOfNames="db_one db_two db_three"
for databaseName in $listOfNames
  echo $databaseName

or just

for databaseName in db_one db_two db_three
  echo $databaseName

Printing newlines with print() in R

Using writeLines also allows you to dispense with the "\n" newline character, by using c(). As in:

writeLines(c("File not supplied.","Usage: ./program F=filename",[additional text for third line]))

This is helpful if you plan on writing a multiline message with combined fixed and variable input, such as the [additional text for third line] above.

How to Split Image Into Multiple Pieces in Python

Not sure if this is the most efficient answer, but it works for me:

import os
import glob
from PIL import Image
Image.MAX_IMAGE_PIXELS = None # to avoid image size warning

imgdir = "/path/to/image/folder"
# if you want file of a specific extension (.png):
filelist = [f for f in glob.glob(imgdir + "**/*.png", recursive=True)]
savedir = "/path/to/image/folder/output"

start_pos = start_x, start_y = (0, 0)
cropped_image_size = w, h = (500, 500)

for file in filelist:
    img =
    width, height = img.size

    frame_num = 1
    for col_i in range(0, width, w):
        for row_i in range(0, height, h):
            crop = img.crop((col_i, row_i, col_i + w, row_i + h))
            name = os.path.basename(file)
            name = os.path.splitext(name)[0]
            save_to= os.path.join(savedir, name+"_{:03}.png")
            frame_num += 1

This is mostly based on DataScienceGuy answer here

AWS EFS vs EBS vs S3 (differences & when to use?)

The main difference between EBS and EFS is that EBS is only accessible from a single EC2 instance in your particular AWS region, while EFS allows you to mount the file system across multiple regions and instances.

Finally, Amazon S3 is an object store good at storing vast numbers of backups or user files.

How to download fetch response in react as file

This worked for me.

const requestOptions = {
method: 'GET',
headers: { 'Content-Type': 'application/json' }

fetch(`${url}`, requestOptions)
.then((res) => {
    return res.blob();
.then((blob) => {
    const href = window.URL.createObjectURL(blob);
    const link = document.createElement('a');
    link.href = href;
    link.setAttribute('download', 'config.json'); //or any other extension
.catch((err) => {
    return Promise.reject({ Error: 'Something Went Wrong', err });

SQL/mysql - Select distinct/UNIQUE but return all columns?

For SQL Server you can use the dense_rank and additional windowing functions to get all rows AND columns with duplicated values on specified columns. Here is an example...

with t as (
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r1' union all
    select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r2' union all
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r3' union all
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r4' union all
    select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r5' union all
    select col1 = 'a', col2 = 'a', col3 = 'a', other = 'r6'
), tdr as (
        total_dr_rows = count(*) over(partition by dr)
    from (
            dr = dense_rank() over(order by col1, col2, col3),
            dr_rn = row_number() over(partition by col1, col2, col3 order by other)
    ) x

select * from tdr where total_dr_rows > 1

This is taking a row count for each distinct combination of col1, col2, and col3.

What is the difference between background and background-color

With background you can set all background properties like:

  • background-color
  • background-image
  • background-repeat
  • background-position

With background-color you can just specify the color of the background

background: url(example.jpg) no-repeat center center #fff;


background-image: url(example.jpg);
background-position: center center;
background-repeat: no-repeat;
background-color: #fff;

More info

(See Caption: Background - Shorthand property)

Converting SVG to PNG using C#

When I had to rasterize svgs on the server, I ended up using P/Invoke to call librsvg functions (you can get the dlls from a windows version of the GIMP image editing program).

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool SetDllDirectory(string pathname);

[DllImport("libgobject-2.0-0.dll", SetLastError = true)]
static extern void g_type_init(); 

[DllImport("librsvg-2-2.dll", SetLastError = true)]
static extern IntPtr rsvg_pixbuf_from_file_at_size(string file_name, int width, int height, out IntPtr error);

[DllImport("libgdk_pixbuf-2.0-0.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
static extern bool gdk_pixbuf_save(IntPtr pixbuf, string filename, string type, out IntPtr error, __arglist);

public static void RasterizeSvg(string inputFileName, string outputFileName)
    bool callSuccessful = SetDllDirectory("C:\\Program Files\\GIMP-2.0\\bin");
    if (!callSuccessful)
        throw new Exception("Could not set DLL directory");
    IntPtr error;
    IntPtr result = rsvg_pixbuf_from_file_at_size(inputFileName, -1, -1, out error);
    if (error != IntPtr.Zero)
        throw new Exception(Marshal.ReadInt32(error).ToString());
    callSuccessful = gdk_pixbuf_save(result, outputFileName, "png", out error, __arglist(null));
    if (!callSuccessful)
        throw new Exception(error.ToInt32().ToString());

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory

An alternative solution is to disable the AOT compiler:

ng build --prod --aot false

python location on mac osx

This one will solve all your problems not only for Mac but works on every basic shell -> Linux also:

If you have a Mac and you've installed python3 like most of us do :) (with brew install - ofc)

your file is located in:


How do you know? -> you can run this on every basic shell Run:

which python3

You should get:


Now this is a symbolic link, how do you know? Run:

ls -al /usr/local/bin/python3 

and you'll get:

/usr/local/bin/python3 -> /usr/local/Cellar/python/3.6.4_4/bin/python3

which means that your


is actually pointing to:


If, for some reason, your


is not pointing to the place you want, which in our case:


just backup it:

cp /usr/local/bin/python3{,.orig} 

and run:

rm -rf /usr/local/bin/python3

now create a new symbolic link:

ln -s /usr/local/Cellar/python/3.6.4_4/bin/python3 /usr/local/bin/python3 

and now your


is pointing to


Check it out by running:

ls -al /usr/local/bin/python3

Formatting struct timespec

I wanted to ask the same question. Here is my current solution to obtain a string like this: 2013-02-07 09:24:40.749355372 I am not sure if there is a more straight forward solution than this, but at least the string format is freely configurable with this approach.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define NANO 1000000000L

// buf needs to store 30 characters
int timespec2str(char *buf, uint len, struct timespec *ts) {
    int ret;
    struct tm t;

    if (localtime_r(&(ts->tv_sec), &t) == NULL)
        return 1;

    ret = strftime(buf, len, "%F %T", &t);
    if (ret == 0)
        return 2;
    len -= ret - 1;

    ret = snprintf(&buf[strlen(buf)], len, ".%09ld", ts->tv_nsec);
    if (ret >= len)
        return 3;

    return 0;

int main(int argc, char **argv) {
    clockid_t clk_id = CLOCK_REALTIME;
    const uint TIME_FMT = strlen("2012-12-31 12:59:59.123456789") + 1;
    char timestr[TIME_FMT];

    struct timespec ts, res;
    clock_getres(clk_id, &res);
    clock_gettime(clk_id, &ts);

    if (timespec2str(timestr, sizeof(timestr), &ts) != 0) {
        printf("timespec2str failed!\n");
        return EXIT_FAILURE;
    } else {
        unsigned long resol = res.tv_sec * NANO + res.tv_nsec;
        printf("CLOCK_REALTIME: res=%ld ns, time=%s\n", resol, timestr);
        return EXIT_SUCCESS;


gcc mwe.c -lrt 
$ ./a.out 
CLOCK_REALTIME: res=1 ns, time=2013-02-07 13:41:17.994326501

Spring JSON request getting 406 (not Acceptable)

There is another case where this status will be returned: if the Jackson mapper cannot figure out how to serialize your bean. For example, if you have two accessor methods for the same boolean property, isFoo() and getFoo().

What's happening is that Spring's MappingJackson2HttpMessageConverter calls Jackson's StdSerializerProvider to see if it can convert your object. At the bottom of the call chain, StdSerializerProvider._createAndCacheUntypedSerializer throws a JsonMappingException with an informative message. However, this exception is swallowed by StdSerializerProvider._createAndCacheUntypedSerializer, which tells Spring that it can't convert the object. Having run out of converters, Spring reports that it's not being given an Accept header that it can use, which of course is bogus when you're giving it */*.

There is a bug for this behavior, but it was closed as "cannot reproduce": the method that's being called doesn't declare that it can throw, so swallowing exceptions is apparently an appropriate solution (yes, that was sarcasm). Unfortunately, Jackson doesn't have any logging ... and there are a lot of comments in the codebase wishing it did, so I suspect this isn't the only hidden gotcha.

Centering elements in jQuery Mobile

This works


<section id="wrapper">
    <div data-role="page">


#wrapper { 
    margin:0 auto;

How do I navigate to a parent route from a child route?

You can navigate to your parent root like this

this.router.navigate(['.'], { relativeTo: this.activeRoute.parent });

You will need to inject the current active Route in the constructor

    private router: Router,
    private activeRoute: ActivatedRoute) {


What happens to C# Dictionary<int, int> lookup if the key does not exist?

You should check for Dictionary.ContainsKey(int key) before trying to pull out the value.

Dictionary<int, int> myDictionary = new Dictionary<int, int>();

int keyToFind = 7;
    myValueLookup = myDictionay[keyToFind];
    // do work...
    // the key doesn't exist.

Cannot edit in read-only editor VS Code

If your code takes input from a user you can't just use output tab. You have to use any terminal as Jordan Stefanelli have said.

  1. just go to terminal tab and select powershell or default terminal
  2. type python
  3. you will be able to input

How to deal with the URISyntaxException

Use % encoding for the ^ character, viz.

How to solve PHP error 'Notice: Array to string conversion in...'

$result = ob_get_clean();

if you want to capture the result in a variable

How to decrypt hash stored by bcrypt

# Maybe you search this ??
For example in my case I use Symfony 4.4 (PHP).
If you want to update User, you need to insert the User password 
encrypted and test with the current Password not encrypted to verify 
if it's the same User. 

For example :

public function updateUser(Request $req)
         $entityManager = $this->getDoctrine()->getManager();
         $repository = $entityManager->getRepository(User::class);
         $user = $repository->find($req->get(id)); /// get User from your DB

         if($user == null){
            throw  $this->createNotFoundException('User don't exist!!', $user);
         $password_old_encrypted = $user->getPassword();//in your DB is always encrypted.
         $passwordToUpdate = $req->get('password'); // not encrypted yet from request.

         $passwordToUpdateEncrypted = password_hash($passwordToUpdate , PASSWORD_DEFAULT);

          ////////////VERIFY IF IT'S THE SAME PASSWORD
         $isPass = password_verify($passwordToUpdateEncrypted , $password_old_encrypted );

         if($isPass === false){ // failure
            throw  $this->createNotFoundException('Your password it's not verify', null);

        return $isPass; //// true!! it's the same password !!!


Select random lines from a file

Well According to a comment on the shuf answer he shuffed 78 000 000 000 lines in under a minute.

Challenge accepted...

EDIT: I beat my own record

powershuf did it in 0.047 seconds

$ time ./ -n 10 --file lines_78000000000.txt > /dev/null 
./ -n 10 --file lines_78000000000.txt > /dev/null  0.02s user 0.01s system 80% cpu 0.047 total

The reason it is so fast, well I don't read the whole file and just move the file pointer 10 times and print the line after the pointer.

Gitlab Repo

Old attempt

First I needed a file of lines:

seq 1 78 | xargs -n 1 -P 16 -I% seq 1 1000 | xargs -n 1 -P 16 -I% echo "" > lines_78000.txt
seq 1 1000 | xargs -n 1 -P 16 -I% cat lines_78000.txt > lines_78000000.txt
seq 1 1000 | xargs -n 1 -P 16 -I% cat lines_78000000.txt > lines_78000000000.txt

This gives me a a file with 78 Billion newlines ;-)

Now for the shuf part:

$ time shuf -n 10 lines_78000000000.txt

shuf -n 10 lines_78000000000.txt  2171.20s user 22.17s system 99% cpu 36:35.80 total

The bottleneck was CPU and not using multiple threads, it pinned 1 core at 100% the other 15 were not used.

Python is what I regularly use so that's what I'll use to make this faster:

import random
f = open("lines_78000000000.txt", "rt")
count = 0
while 1:
  buffer =
  if not buffer: break
  count += buffer.count('\n')

for i in range(10):
  f.readline(random.randint(1, count))

This got me just under a minute:

$ time ./         

./  42.57s user 16.19s system 98% cpu 59.752 total

I did this on a Lenovo X1 extreme 2nd gen with the i9 and Samsung NVMe which gives me plenty read and write speed.

I know it can get faster but I'll leave some room to give others a try.

Line counter source: Luther Blissett

Storyboard - refer to ViewController in AppDelegate

Have a look at the documentation for -[UIStoryboard instantiateViewControllerWithIdentifier:]. This allows you to instantiate a view controller from your storyboard using the identifier that you set in the IB Attributes Inspector:

enter image description here

EDITED to add example code:

UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard"
                                                         bundle: nil];

MyViewController *controller = (MyViewController*)[mainStoryboard 
                    instantiateViewControllerWithIdentifier: @"<Controller ID>"];

Java Scanner class reading strings

It's because the in.nextInt() doesn't change line. So you first "enter" (after you press 3 ) cause the endOfLine read by your in.nextLine() in your loop.

Here a small change that you can do:

int nnames;
    String names[];

    System.out.print("How many names are you going to save: ");
    Scanner in = new Scanner(;
    nnames = Integer.parseInt(in.nextLine());
    names = new String[nnames];

    for (int i = 0; i < names.length; i++){
            System.out.print("Type a name: ");
            names[i] = in.nextLine();

How can I account for period (AM/PM) using strftime?

>>> from datetime import datetime
>>> print("%H:%M %p"))
15:31 AM

Try replacing %I with %H.

PLS-00201 - identifier must be declared

you should give permission on your db

grant execute on (packageName or tableName) to user;

Google Maps API warning: NoApiKeys

A key currently still is not required ("required" in the meaning "it will not work without"), but I think there is a good reason for the warning.

But in the documentation you may read now : "All JavaScript API applications require authentication."

I'm sure that it's planned for the future , that Javascript API Applications will not work without a key(as it has been in V2).

You better use a key when you want to be sure that your application will still work in 1 or 2 years.

How to make promises work in IE11

If you want this type of code to run in IE11 (which does not support much of ES6 at all), then you need to get a 3rd party promise library (like Bluebird), include that library and change your coding to use ES5 coding structures (no arrow functions, no let, etc...) so you can live within the limits of what older browsers support.

Or, you can use a transpiler (like Babel) to convert your ES6 code to ES5 code that will work in older browsers.

Here's a version of your code written in ES5 syntax with the Bluebird promise library:

<script src=""></script>


'use strict';

var promise = new Promise(function(resolve) {
    setTimeout(function() {
    }, 1000);

promise.then(function(result) {
    alert("Fulfilled: " + result);
}, function(error) {
    alert("Rejected: " + error);


What is the GAC in .NET?

The Global Assembly Cache (GAC) is a folder in Windows directory to store the .NET assemblies that are specifically designated to be shared by all applications executed on a system. Assemblies can be shared among multiple applications on the machine by registering them in global Assembly cache(GAC). GAC is a machine wide a local cache of assemblies maintained by the .NET Framework.

Https Connection Android

Probably you can try something like this. This helped me

    SslContextFactory sec = new SslContextFactory();

    org.eclipse.jetty.websocket.client.WebSocketClient client = new WebSocketClient(sec);

How to do a case sensitive search in WHERE clause (I'm using SQL Server)?

By using collation or casting to binary, like this:

FROM Users
    Username = @Username COLLATE SQL_Latin1_General_CP1_CS_AS
    AND Password = @Password COLLATE SQL_Latin1_General_CP1_CS_AS
    AND Username = @Username 
    AND Password = @Password 

The duplication of username/password exists to give the engine the possibility of using indexes. The collation above is a Case Sensitive collation, change to the one you need if necessary.

The second, casting to binary, could be done like this:

FROM Users
    CAST(Username as varbinary(100)) = CAST(@Username as varbinary))
    AND CAST(Password as varbinary(100)) = CAST(@Password as varbinary(100))
    AND Username = @Username 
    AND Password = @Password 

How to return values in javascript

It's difficult to tell what you're actually trying to do and if this is what you really need but you might also use a callback:

function myFunction(value1,callback)
     //Do stuff and 

     if(typeof callback == 'function'){

myFunction("1", function(value2, value3){
    if(value2 && value3)
    //Do some stuff

How to make a great R reproducible example

Often you need some data for an example, however, you don't want to post your exact data. To use some existing data.frame in established library, use data command to import it.



and then do the problem

your problem demostrated on the mtcars data set

What's the best way to parse command line arguments?

This answer suggests optparse which is appropriate for older Python versions. For Python 2.7 and above, argparse replaces optparse. See this answer for more information.

As other people pointed out, you are better off going with optparse over getopt. getopt is pretty much a one-to-one mapping of the standard getopt(3) C library functions, and not very easy to use.

optparse, while being a bit more verbose, is much better structured and simpler to extend later on.

Here's a typical line to add an option to your parser:

parser.add_option('-q', '--query',
            action="store", dest="query",
            help="query string", default="spam")

It pretty much speaks for itself; at processing time, it will accept -q or --query as options, store the argument in an attribute called query and has a default value if you don't specify it. It is also self-documenting in that you declare the help argument (which will be used when run with -h/--help) right there with the option.

Usually you parse your arguments with:

options, args = parser.parse_args()

This will, by default, parse the standard arguments passed to the script (sys.argv[1:])

options.query will then be set to the value you passed to the script.

You create a parser simply by doing

parser = optparse.OptionParser()

These are all the basics you need. Here's a complete Python script that shows this:

import optparse

parser = optparse.OptionParser()

parser.add_option('-q', '--query',
    action="store", dest="query",
    help="query string", default="spam")

options, args = parser.parse_args()

print 'Query string:', options.query

5 lines of python that show you the basics.

Save it in, and run it once with


and once with

python --query myquery

Beyond that, you will find that optparse is very easy to extend. In one of my projects, I created a Command class which allows you to nest subcommands in a command tree easily. It uses optparse heavily to chain commands together. It's not something I can easily explain in a few lines, but feel free to browse around in my repository for the main class, as well as a class that uses it and the option parser

Sending POST data in Android

If you just want to append data to the Url You can do so by using HttpUrlConnection since HttpClient is now deprecated. A better way would be to use a library like-

Volley Retrofit

We can post data to the php script and fetch result and display it by using this code performed Through AsyncTask class.

    private class LongOperation  extends AsyncTask<String, Void, Void> {

    // Required initialization

    private String Content;
    private String Error = null;
    private ProgressDialog Dialog = new ProgressDialog(Login.this);
    String data ="";
    int sizeData = 0;

    protected void onPreExecute() {
        // NOTE: You can call UI Element here.

        //Start Progress Dialog (Message)

        Dialog.setMessage("Please wait..");;

            // Set Request parameter
            data +="&" + URLEncoder.encode("username", "UTF-8") + "="+edittext.getText();

        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block


    // Call after onPreExecute method
    protected Void doInBackground(String... urls) {

        /************ Make Post Call To Web Server ***********/
        BufferedReader reader=null;

        // Send data

            // Defined URL  where to send data
            URL url = new URL(urls[0]);

            // Send POST data request

            URLConnection conn = url.openConnection();

            conn.setConnectTimeout(5000);//define connection timeout 
            conn.setReadTimeout(5000);//define read timeout
            OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
            wr.write( data );

            // Get the server response

            reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            StringBuilder sb = new StringBuilder();
            String line = null;

            // Read Server Response
            while((line = reader.readLine()) != null)
                // Append server response in string
                sb.append(line + " ");

            // Append Server Response To Content String
            Content = sb.toString();

        catch(Exception ex)
            Error = ex.getMessage();


            catch(Exception ex) {}

        return null;

    protected void onPostExecute(Void unused) {
        // NOTE: You can call UI Element here.

        // Close progress dialog

        if (Error != null) {

                Toast.makeText(getApplicationContext(),"Error encountered",Toast.LENGTH_LONG).show();

        else {

            try {

                JSONObject jsonRootObject = new JSONObject(Content);

                JSONObject json2 =jsonRootObject.getJSONObject("jsonkey");//pass jsonkey here

                String id =json2.optString("id").toString();//parse json to string through parameters

     //the result is stored in string id. you can display it now

            } catch (JSONException e) {e.printStackTrace();}




But using libraries such as volley or retrofit is much better option because Asynctask class and HttpurlConnection is slower compared to libraries. Also the library will fetch everything and is faster as well.

how to refresh page in angular 2

The simplest possible solution I found was:

In your markup:

<a [href]="location.path()">Reload</a>

and in your component typescript file:

        private location: Location
  ) { }

Reading a string with spaces with sscanf

I guess this is what you want, it does exactly what you specified.


int main(int argc, char** argv) {
    int age;
    char* buffer;
    buffer = malloc(200 * sizeof(char));
    sscanf("19 cool kid", "%d cool %s", &age, buffer);
    printf("cool %s is %d years old\n", buffer, age);
    return 0;

The format expects: first a number (and puts it at where &age points to), then whitespace (zero or more), then the literal string "cool", then whitespace (zero or more) again, and then finally a string (and put that at whatever buffer points to). You forgot the "cool" part in your format string, so the format then just assumes that is the string you were wanting to assign to buffer. But you don't want to assign that string, only skip it.

Alternative, you could also have a format string like: "%d %s %s", but then you must assign another buffer for it (with a different name), and print it as: "%s %s is %d years old\n".

What's the location of the JavaFX runtime JAR file, jfxrt.jar, on Linux?

The location of jfxrt.jar in JDK 1.8 (Windows) is:

C:\Program Files\Java\jdk1.8.0_05\jre\lib\ext\jfxrt.jar

What's a standard way to do a no-op in python?

If you need a function that behaves as a nop, try

nop = lambda *a, **k: None

Sometimes I do stuff like this when I'm making dependencies optional:

    import foo

# Doesn't break when foo is missing:

How to upload files to server using JSP/Servlet?

If you happen to use Spring MVC, this is how to: (I'm leaving this here in case someone find it useful).

Use a form with enctype attribute set to "multipart/form-data" (Same as BalusC's Answer)

<form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file" />
    <input type="submit" value="Upload"/>

In your controller, map the request parameter file to MultipartFile type as follows:

@RequestMapping(value = "/upload", method = RequestMethod.POST)
public void handleUpload(@RequestParam("file") MultipartFile file) throws IOException {
    if (!file.isEmpty()) {
            byte[] bytes = file.getBytes(); // alternatively, file.getInputStream();
            // application logic

You can get the filename and size using MultipartFile's getOriginalFilename() and getSize().

I've tested this with Spring version 4.1.1.RELEASE.

Press TAB and then ENTER key in Selenium WebDriver

Using Java:

WebElement webElement = driver.findElement(By.xpath(""));//You can use xpath, ID or name whatever you like

JSON Post with Customized HTTPHeader Field

Just wanted to update this thread for future developers.

JQuery >1.12 Now supports being able to change every little piece of the request through ($.post({...}). see second function signature in

Gridview get Checkbox.Checked value

If you want a method other than findcontrol try the following:

 GridViewRow row = Gridview1.SelectedRow;
 int CustomerId = int.parse(row.Cells[0].Text);// to get the column value
 CheckBox checkbox1= row.Cells[0].Controls[0] as CheckBox; // you can access the controls like this

setting request headers in selenium

With the solutions already discussed above the most reliable one is using Browsermob-Proxy

But while working with the remote grid machine, Browsermob-proxy isn't really helpful.

This is how I fixed the problem in my case. Hopefully, might be helpful for anyone with a similar setup.

  1. Add the ModHeader extension to the chrome browser

How to download the Modheader? Link

ChromeOptions options = new ChromeOptions();
options.addExtensions(new File(C://Downloads//modheader//modheader.crx));

// Set the Desired capabilities 
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(ChromeOptions.CAPABILITY, options);

// Instantiate the chrome driver with capabilities
WebDriver driver = new RemoteWebDriver(new URL(YOUR_HUB_URL), options);
  1. Go to the browser extensions and capture the Local Storage context ID of the ModHeader

Capture ID from ModHeader

  1. Navigate to the URL of the ModHeader to set the Local Storage Context


// set the context on the extension so the localStorage can be accessed

Where `idgpnmonknjnojddfkpgkljpfnnfcklj` is the value captured from the Step# 2
  1. Now add the headers to the request using Javascript


         "localStorage.setItem('profiles', JSON.stringify([{  title: 'Selenium', hideComment: true, appendMode: '', 
             headers: [                        
               {enabled: true, name: 'token-1', value: 'value-1', comment: ''},
               {enabled: true, name: 'token-2', value: 'value-2', comment: ''}
             respHeaders: [],
             filters: []

Where token-1, value-1, token-2, value-2 are the request headers and values that are to be added.

  1. Now navigate to the required web-application.


How to add a button dynamically in Android?

try this

private void createLayoutDynamically(int n) {

    for (int i = 0; i < n; i++) {
        Button myButton = new Button(this);
        myButton.setText("Button :"+i);
        final int id_ = myButton.getId();

        LinearLayout layout = (LinearLayout) findViewById(;

        myButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                        "Button clicked index = " + id_, Toast.LENGTH_SHORT)

Java 8 lambda get and remove element from list

When we want to get multiple elements from a List into a new list (filter using a predicate) and remove them from the existing list, I could not find a proper answer anywhere.

Here is how we can do it using Java Streaming API partitioning.

Map<Boolean, List<ProducerDTO>> classifiedElements = producersProcedureActive
    .collect(Collectors.partitioningBy(producer -> producer.getPod().equals(pod)));

// get two new lists 
List<ProducerDTO> matching = classifiedElements.get(true);
List<ProducerDTO> nonMatching = classifiedElements.get(false);

// OR get non-matching elements to the existing list
producersProcedureActive = classifiedElements.get(false);

This way you effectively remove the filtered elements from the original list and add them to a new list.

Refer the 5.2. Collectors.partitioningBy section of this article.

Find the greatest number in a list of numbers

    #Ask for number input
first = int(raw_input('Please type a number: '))
second = int(raw_input('Please type a number: '))
third = int(raw_input('Please type a number: '))
fourth = int(raw_input('Please type a number: '))
fifth = int(raw_input('Please type a number: '))
sixth = int(raw_input('Please type a number: '))
seventh = int(raw_input('Please type a number: '))
eighth = int(raw_input('Please type a number: '))
ninth = int(raw_input('Please type a number: '))
tenth = int(raw_input('Please type a number: '))

    #create a list for variables
sorted_list = [first, second, third, fourth, fifth, sixth, seventh, 
              eighth, ninth, tenth]
odd_numbers = []

    #filter list and add odd numbers to new list
for value in sorted_list:
    if value%2 != 0:
print 'The greatest odd number you typed was:', max(odd_numbers)

Get refresh token google api

Hi I followed following steps and I had been able to get the refresh token.

Authorization flow has two steps.

  1. Is to obtain the authorization code using URL.

    For that a post request is sent providing following parameters. 'scope=' + SCOPE + '&client_id=' + CLIENTID + '&redirect_uri=' + REDIRECT + '&response_type=' + TYPE + '&access_type=offline' Providing above will receive a authorization code.

  2. Retrieving AcessToken and RefreshToken using URL. For that a post request is sent providing following parameters.

    "code" : code, "client_id" : CID, "client_secret" : CSECRET, "redirect_uri" : REDIRECT, "grant_type" : "authorization_code",

So in your first attempt once you authorize the permissions you will be able to get the Refresh token. Subsequent attempts will not provide the refresh token. If you want the token again the revoke the access in you application.

Hope this will help someone cheers :)

How to get only numeric column values?

The other answers indicating using IsNumeric in the where clause are correct, as far as they go, but it's important to remember that it returns 1 if the value can be converted to any numeric type. As such, oddities such as "1d3" will make it through the filter.

If you need only values composed of digits, search for that explicitly:

SELECT column1 FROM table WHERE column1 not like '%[^0-9]%'

The above is filtering to reject any column which contains a non-digit character

Note that in any case, you're going to incur a table scan, indexes are useless for this sort of query.

How can I find the version of php that is running on a distinct domain name?



another way is getting HTTP Headers by this site ( or firefox add-on for getting HTTP Headers...

Best Regards

Passing parameters to a JQuery function

Do you want to pass parameters to another page or to the function only?

If only the function, you don't need to add the $.ajax() tvanfosson added. Just add your function content instead. Like:

function DoAction (id, name ) {
    // ...
    // do anything you want here
    alert ("id: "+id+" - name: "+name);

This will return an alert box with the id and name values.

Pull request vs Merge request

They are the same feature

Merge or pull requests are created in a git management application and ask an assigned person to merge two branches. Tools such as GitHub and Bitbucket choose the name pull request since the first manual action would be to pull the feature branch. Tools such as GitLab and Gitorious choose the name merge request since that is the final action that is requested of the assignee. In this article we’ll refer to them as merge requests.


Syntax for a for loop in ruby

To iterate a loop a fixed number of times, try:

n.times do
  #Something to be done n times

My docker container has no internet

I do not know what I am doing but that worked for me :

OTHER_BRIDGE=br-xxxxx # this is the other random docker bridge (`ip addr` to find)    
service docker stop

ip link set dev $OTHER_BRIDGE down
ip link set dev docker0 down
ip link delete $OTHER_BRIDGE type bridge
ip link delete docker0 type bridge
service docker start && service docker stop

iptables -t nat -A POSTROUTING ! -o docker0 -s -j MASQUERADE
iptables -t nat -A POSTROUTING ! -o docker0 -s -j MASQUERADE

service docker start

Copy/duplicate database without using mysqldump

I can see you said you didn't want to use mysqldump, but I reached this page while looking for a similar solution and others might find it as well. With that in mind, here is a simple way to duplicate a database from the command line of a windows server:

  1. Create the target database using MySQLAdmin or your preferred method. In this example, db2 is the target database, where the source database db1 will be copied.
  2. Execute the following statement on a command line:

mysqldump -h [server] -u [user] -p[password] db1 | mysql -h [server] -u [user] -p[password] db2

Note: There is NO space between -p and [password]

Order data frame rows according to vector with specific order

Here's a similar system for the situation where you have a variable you want to sort by, initially, but then you want to sort by a secondary variable according to the order that this secondary variable first appears in the initial sort.

In the function below, the initial sort variable is called order_by and the secondary variable is called order_along - as in "order by this variable along its initial order".

library(dplyr, warn.conflicts = FALSE)
df <- structure(
    msoa11hclnm = c(
      "Bewbush", "Tilgate", "Felpham",
      "Selsey", "Brunswick", "Ratton", "Ore", "Polegate", "Mile Oak",
      "Upperton", "Arundel", "Kemptown"
    lad20nm = c(
      "Crawley", "Crawley",
      "Arun", "Chichester", "Brighton and Hove", "Eastbourne", "Hastings",
      "Wealden", "Brighton and Hove", "Eastbourne", "Arun", "Brighton and Hove"
    shape_area = c(
      1328821, 3089180, 3540014, 9738033, 448888, 10152663, 5517102,
      7036428, 5656430, 2653589, 72832514, 826151
  row.names = c(NA, -12L), class = "data.frame"

this does not give me what I need:

df %>% 
  dplyr::arrange(shape_area, lad20nm)
#>    msoa11hclnm           lad20nm shape_area
#> 1    Brunswick Brighton and Hove     448888
#> 2     Kemptown Brighton and Hove     826151
#> 3      Bewbush           Crawley    1328821
#> 4     Upperton        Eastbourne    2653589
#> 5      Tilgate           Crawley    3089180
#> 6      Felpham              Arun    3540014
#> 7          Ore          Hastings    5517102
#> 8     Mile Oak Brighton and Hove    5656430
#> 9     Polegate           Wealden    7036428
#> 10      Selsey        Chichester    9738033
#> 11      Ratton        Eastbourne   10152663
#> 12     Arundel              Arun   72832514

Here’s a function:

order_along <- function(df, order_along, order_by) {
  cols <- colnames(df)
  df <- df %>%
    dplyr::arrange({{ order_by }})
  df %>% 
    dplyr::select({{ order_along }}) %>% 
    dplyr::distinct() %>% 
    dplyr::full_join(df) %>% 

order_along(df, lad20nm, shape_area)
#> Joining, by = "lad20nm"
#>    msoa11hclnm           lad20nm shape_area
#> 1    Brunswick Brighton and Hove     448888
#> 2     Kemptown Brighton and Hove     826151
#> 3     Mile Oak Brighton and Hove    5656430
#> 4      Bewbush           Crawley    1328821
#> 5      Tilgate           Crawley    3089180
#> 6     Upperton        Eastbourne    2653589
#> 7       Ratton        Eastbourne   10152663
#> 8      Felpham              Arun    3540014
#> 9      Arundel              Arun   72832514
#> 10         Ore          Hastings    5517102
#> 11    Polegate           Wealden    7036428
#> 12      Selsey        Chichester    9738033

Created on 2021-01-12 by the reprex package (v0.3.0)

How can I create a self-signed cert for localhost?

Yes and no. Self signed certificates result in that warning message because the certificate was not signed by a trusted Certificate Authority. There are a few options that you can consider to remove this warning on your local machine. See the highest ranked answers to this question for details:

What do I need to do to get Internet Explorer 8 to accept a self signed certificate?

Hope this helps!


Sorry, I wasn't initially aware that you were constrained to localhost. You can attempt to follow the directions on the the link below to "Generate a Self Signed Certificate with the Correct Common Name."

MySQL : transaction within a stored procedure

Just an alternative to the code by rkosegi,


    .. Declare statements ..

          .. set any flags etc  eg. SET @flag = 0; ..


        .. Query 1 ..
        .. Query 2 ..
        .. Query 3 ..

    .. eg. SET @flag = 1; ..


How to split a string in shell and get the last field

If you like python and have an option to install a package, you can use this python utility.

# install pythonp
pythonp -m pip install pythonp

echo "1:2:3:4:5" | pythonp "l.split(':')[-1]"

Hibernate: ids for this class must be manually assigned before calling save()

Assign primary key in hibernate

Make sure that the attribute is primary key and Auto Incrementable in the database. Then map it into the data class with the annotation with @GeneratedValue annotation using IDENTITY.

@Table(name = "client")
data class Client(
        @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id") private val id: Int? = null



Inline labels in Matplotlib

A simpler approach like the one Ioannis Filippidis do :

import matplotlib.pyplot as plt
import numpy as np

# evenly sampled time at 200ms intervals
tMin=-1 ;tMax=10
t = np.arange(tMin, tMax, 0.1)

# red dashes, blue points default
plt.plot(t, 22*t, 'r--', t, t**2, 'b')

factor=3/4 ;offset=20  # text position in view  
plt.text(textPosition[0],textPosition[1]+offset,'22  t',color='red',fontsize=20)
plt.text(textPosition[0],textPosition[1]+offset, 't^2', bbox=dict(facecolor='blue', alpha=0.5),fontsize=20)

code python 3 on sageCell

Errno 10061 : No connection could be made because the target machine actively refused it ( client - server )

There is no relationship between error and firewall.

first, run server program,
then run client program in another shell of python

and it will work

git: fatal: Could not read from remote repository

Your ssh key most likely had been removed from ssh agent

ssh-add ~/.ssh/id_rsa

where id_rsa is a ssh key associated with git repo


You may get Could not open a connection to your authentication agent. error to resolve that you need to start the agent first by:

eval `ssh-agent -s`

Differences between Lodash and Underscore.js

In 2014 I still think my point holds:

IMHO, this discussion got blown out of proportion quite a bit. Quoting the aforementioned blog post:

Most JavaScript utility libraries, such as Underscore, Valentine, and wu, rely on the “native-first dual approach.” This approach prefers native implementations, falling back to vanilla JavaScript only if the native equivalent is not supported. But jsPerf revealed an interesting trend: the most efficient way to iterate over an array or array-like collection is to avoid the native implementations entirely, opting for simple loops instead.

As if "simple loops" and "vanilla Javascript" are more native than Array or Object method implementations. Jeez ...

It certainly would be nice to have a single source of truth, but there isn't. Even if you've been told otherwise, there is no Vanilla God, my dear. I'm sorry. The only assumption that really holds is that we are all writing JavaScript code that aims at performing well in all major browsers, knowing that all of them have different implementations of the same things. It's a bitch to cope with, to put it mildly. But that's the premise, whether you like it or not.

Maybe all of you are working on large scale projects that need twitterish performance so that you really see the difference between 850,000 (Underscore.js) vs. 2,500,000 (Lodash) iterations over a list per second right now!

I for one am not. I mean, I worked on projects where I had to address performance issues, but they were never solved or caused by neither Underscore.js nor Lodash. And unless I get hold of the real differences in implementation and performance (we're talking C++ right now) of, let’s say, a loop over an iterable (object or array, sparse or not!), I rather don't get bothered with any claims based on the results of a benchmark platform that is already opinionated.

It only needs one single update of, let’s say, Rhino to set its Array method implementations on fire in a fashion that not a single "medieval loop methods perform better and forever and whatnot" priest can argue his/her way around the simple fact that all of a sudden array methods in Firefox are much faster than his/her opinionated brainfuck. Man, you just can't cheat your runtime environment by cheating your runtime environment! Think about that when promoting ...

your utility belt

... next time.

So to keep it relevant:

  • Use Underscore.js if you're into convenience without sacrificing native'ish.
  • Use Lodash if you're into convenience and like its extended feature catalogue (deep copy, etc.) and if you're in desperate need of instant performance and most importantly don't mind settling for an alternative as soon as native API's outshine opinionated workarounds. Which is going to happen soon. Period.
  • There's even a third solution. DIY! Know your environments. Know about inconsistencies. Read their (John-David's and Jeremy's) code. Don't use this or that without being able to explain why a consistency/compatibility layer is really needed and enhances your workflow or improves the performance of your application. It is very likely that your requirements are satisfied with a simple polyfill that you're perfectly able to write yourself. Both libraries are just plain vanilla with a little bit of sugar. They both just fight over who's serving the sweetest pie. But believe me, in the end both are only cooking with water. There's no Vanilla God so there can't be no Vanilla pope, right?

Choose whatever approach fits your needs the most. As usual. I'd prefer fallbacks on actual implementations over opinionated runtime cheats anytime, but even that seems to be a matter of taste nowadays. Stick to quality resources like and and you'll be just fine.

How do I create an abstract base class in JavaScript?

You might want to check out Dean Edwards' Base Class:

Alternatively, there is this example / article by Douglas Crockford on classical inheritance in JavaScript:

Calling stored procedure with return value

I know this is old, but i stumbled on it with Google.

If you have a return value in your stored procedure say "Return 1" - not using output parameters.

You can do the following - "@RETURN_VALUE" is silently added to every command object. NO NEED TO EXPLICITLY ADD

    rtn = (int)cmd.Parameters["@RETURN_VALUE"].Value;

What's the best way to center your HTML email content in the browser window (or email client preview pane)?

In some cases margin="0 auto" won't cut the mustard when center aligning a html email in Outlook 2007, 2010, 2013.

Try the following:

Wrap your content in another table with style="table-layout: fixed;" and align=“center”.

<table cellpadding="0" cellspacing="0" border="0" style="table-layout: fixed;" align="center">

Does Internet Explorer 8 support HTML 5?

You can use this IE HTML5 shim script to gain a basic level of support for the new semantic elements in HTML5 such as <article>.

Python: slicing a multi-dimensional array

If you use numpy, this is easy:

slice = arr[:2,:2]

or if you want the 0's,

slice = arr[0:2,0:2]

You'll get the same result.

*note that slice is actually the name of a builtin-type. Generally, I would advise giving your object a different "name".

Another way, if you're working with lists of lists*:

slice = [arr[i][0:2] for i in range(0,2)]

(Note that the 0's here are unnecessary: [arr[i][:2] for i in range(2)] would also work.).

What I did here is that I take each desired row 1 at a time (arr[i]). I then slice the columns I want out of that row and add it to the list that I'm building.

If you naively try: arr[0:2] You get the first 2 rows which if you then slice again arr[0:2][0:2], you're just slicing the first two rows over again.

*This actually works for numpy arrays too, but it will be slow compared to the "native" solution I posted above.

Turn Pandas Multi-Index into column

The reset_index() is a pandas DataFrame method that will transfer index values into the DataFrame as columns. The default setting for the parameter is drop=False (which will keep the index values as columns).

All you have to do add .reset_index(inplace=True) after the name of the DataFrame: