Programs & Examples On #Drawrectangle

How to create a Rectangle object in Java using g.fillRect method

Note:drawRect and fillRect are different.

Draws the outline of the specified rectangle:

public void drawRect(int x,
        int y,
        int width,
        int height)

Fills the specified rectangle. The rectangle is filled using the graphics context's current color:

public abstract void fillRect(int x,
        int y,
        int width,
        int height)

How to find the duration of difference between two dates in java?

Date d2 = new Date();
Date d1 = new Date(1384831803875l);

long diff = d2.getTime() - d1.getTime();
long diffSeconds = diff / 1000 % 60;
long diffMinutes = diff / (60 * 1000) % 60;
long diffHours = diff / (60 * 60 * 1000);
int diffInDays = (int) diff / (1000 * 60 * 60 * 24);

System.out.println(diffInDays+"  days");
System.out.println(diffHours+"  Hour");
System.out.println(diffMinutes+"  min");
System.out.println(diffSeconds+"  sec");

Finding even or odd ID values

ID % 2 reduces all integer (monetary and numeric are allowed, too) numbers to 0 and 1 effectively.
Read about the modulo operator in the manual.

How to change the default docker registry from to my private registry?

Docker official position is explained in issue #11815 :

Issue 11815: Allow to specify default registries used in pull command


Like pointed out earlier (#11815), this would fragment the namespace, and hurt the community pretty badly, making dockerfiles no longer portable.

[the Maintainer] will close this for this reason.

Red Hat had a specific implementation that allowed it (see anwser, but it was refused by Docker upstream projet). It relied on --add-registry argument, which was set in /etc/containers/registries.conf on RHEL/CentOS 7.


Actually, Docker supports registry mirrors (also known as "Run a Registry as a pull-through cache").

C# Connecting Through Proxy

This is easily achieved either programmatically, in your code, or declaratively in either the web.config or the app.config.

You can programmatically create a proxy like so:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("[ultimate destination of your request]");
WebProxy myproxy = new WebProxy("[your proxy address]", [your proxy port number]);
myproxy.BypassProxyOnLocal = false;
request.Proxy = myproxy;
request.Method = "GET";
HttpWebResponse response = (HttpWebResponse) request.GetResponse();

You're basically assigning the WebProxy object to the request object's proxy property. This request will then use the proxy you define.

To achieve the same thing declaratively, you can do the following:

      proxyaddress="http://[your proxy address and port number]"

within your web.config or app.config. This sets a default proxy that all http requests will use. Depending upon exactly what you need to achieve, you may or may not require some of the additional attributes of the defaultProxy / proxy element, so please refer to the documentation for those.

Downloading all maven dependencies to a directory NOT in repository?

I found the next command

mvn dependency:copy-dependencies -Dclassifier=sources


Change Button color onClick

Every time setColor gets hit, you are setting count = 1. You would need to define count outside of the scope of the function. Example:

var count=1;
function setColor(btn, color){
    var property = document.getElementById(btn);
    if (count == 0){ = "#FFFFFF"
    else{ = "#7FFF00"


Cannot get Kerberos service ticket: KrbException: Server not found in Kerberos database (7)

In my case, My principal was kafka/[email protected] I got below lines in the terminal:

>>> KrbKdcReq send: #bytes read=190
>>> KdcAccessibility: remove
>>> KDCRep: init() encoding tag is 126 req type is 13
         cTime is Thu Oct 05 03:42:15 UTC 1995 812864535000
         sTime is Fri May 31 06:43:38 UTC 2019 1559285018000
         suSec is 111309
         error code is 7
         error Message is Server not found in Kerberos database
         cname is kafka/[email protected]
         sname is kafka/[email protected]
         msgType is 30

After hours of checking, I just found the below line has a wrong value in kafka_2.12-2.2.0/


Also I got two entries of and for same IP address.

I changed it to as listeners=SASL_PLAINTEXT:// Then it worked!

According to the below link, the principal should contain the Fully Qualified Domain Name (FQDN) of each host and it should be matched with the principal.

how to make a specific text on TextView BOLD

Based on @mladj0ni's answer, I got the code below to work. The problem was that if you use String.format, it strips out the html markup, so you have to escape the bracket symbols in strings.xml:


<string name="welcome_messages">Hello, %1$s! You have &lt;b>%2$d new messages&lt;/b>.</string>

String unspanned = String.format(Locale.US, "%s%s", getResources().getString(R.string. welcome_messages), 99);

Spanned spanned;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
    spanned = Html.fromHtml(unspanned, Html.FROM_HTML_MODE_LEGACY);
} else {
    spanned = Html.fromHtml(unspanned);


It's simpler than SpannableStringBuilder. As for performance, if you're displaying just one string, then the user won't notice the extra millisecond to parse it.

See the documentation here.

Change link color of the current page with CSS

a:active : when you click on the link and hold it (active!).
a:visited : when the link has already been visited.

If you want the link corresponding to the current page to be highlighted, you can define some specific style to the link -

.currentLink {
   color: #640200;
   background-color: #000000;

Add this new class only to the corresponding li (link), either on server-side or on client-side (using JavaScript).

Unable to Connect to For Cloning

You can try to clone using the HTTPS protocol. Terminal command:

git clone

How to compare oldValues and newValues on React Hooks useEffect?

If you prefer a useEffect replacement approach:

const usePreviousEffect = (fn, inputs = []) => {
  const previousInputsRef = useRef([...inputs])

  useEffect(() => {
    previousInputsRef.current = [...inputs]
  }, inputs)

And use it like this:

  ([prevReceiveAmount, prevSendAmount]) => {
    if (prevReceiveAmount !== receiveAmount) // side effect here
    if (prevSendAmount !== sendAmount) // side effect here
  [receiveAmount, sendAmount]

Note that the first time the effect executes, the previous values passed to your fn will be the same as your initial input values. This would only matter to you if you wanted to do something when a value did not change.

What is a method group in C#?

The first result in your MSDN search said:

The method group identifies the one method to invoke or the set of overloaded methods from which to choose a specific method to invoke

my understanding is that basically because when you just write someInteger.ToString, it may refer to:


or it can refer to:


so it is called a method group.

How to cast List<Object> to List<MyClass>

Your best bet is to create a new List<Customer>, iterate through the List<Object>, add each item to the new list, and return that.

How to style a clicked button in CSS

button:hover is just when you move the cursor over the button.
Try button:active instead...will work for other elements as well

  color: red;_x000D_

'System.OutOfMemoryException' was thrown when there is still plenty of memory free

Increase the Windows process limit to 3gb. (via boot.ini or Vista boot manager)

Why SpringMVC Request method 'GET' not supported?

I solved this error by including a get and post request in my controller: method={RequestMethod.POST, RequestMethod.GET}

How do you get the index of the current iteration of a foreach loop?

Why foreach ?!

The simplest way is using for instead of foreach if you are using List:

for (int i = 0 ; i < myList.Count ; i++)
    // Do something...

Or if you want use foreach:

foreach (string m in myList)
     // Do something...

You can use this to know the index of each loop:


Can I concatenate multiple MySQL rows into one field?

Try this:

DECLARE @Hobbies NVARCHAR(200) = ' '

SELECT @Hobbies = @Hobbies + hobbies + ',' FROM peoples_hobbies WHERE person_id = 5;


set @sql='';
set @result='';
set @separator=' union \r\n';
@sql:=concat('select ''',INFORMATION_SCHEMA.COLUMNS.COLUMN_NAME  ,''' as col_name,',
' FROM ',
) as sql_piece, if(@result:=if(@result='',@sql,concat(@result,@separator,@sql)),'','') as dummy
select @result;

How do I check if a string is valid JSON in Python?

I would say parsing it is the only way you can really entirely tell. Exception will be raised by python's json.loads() function (almost certainly) if not the correct format. However, the the purposes of your example you can probably just check the first couple of non-whitespace characters...

I'm not familiar with the JSON that facebook sends back, but most JSON strings from web apps will start with a open square [ or curly { bracket. No images formats I know of start with those characters.

Conversely if you know what image formats might show up, you can check the start of the string for their signatures to identify images, and assume you have JSON if it's not an image.

Another simple hack to identify a graphic, rather than a text string, in the case you're looking for a graphic, is just to test for non-ASCII characters in the first couple of dozen characters of the string (assuming the JSON is ASCII).

Raise an error manually in T-SQL to jump to BEGIN CATCH block

THROW (Transact-SQL)

Raises an exception and transfers execution to a CATCH block of a TRY…CATCH construct in SQL Server 2017.

Please refer the below link

T-SQL Throw Exception

PHP - how to create a newline character?

For some reason, every single post asking about newline escapes in PHP fails to mention the case that simply inserting a newline into single-quoted strings will do exactly what you think:

ex 1.

 echo 'foo\nbar';

Example 1 clearly does not print the desired result, however, while it is true you cannot escape a newline in single-quotes, you can have one:

ex 2.

 echo 'foo

Example 2 has exactly the desired behavior. Unfortunately the newline that is inserted is operating system dependent. This usually isn't a problem, as web browsers/servers will correctly interpret the newline whether it is \r, \r\n, or \n.

Obviously this solution is not ideal if you plan to distribute the file through other means then a web browser and to multiple operating systems. In that case you should see one of the other answers.

note: using a feature rich text editor you should be able to insert a newline as a binary character(s) that represents a newline on a different operating system than the one editing the file. If all else fails, simply using a hex editor to insert the binary ascii character would do.

How to specify "does not contain" in dplyr filter

Note that %in% returns a logical vector of TRUE and FALSE. To negate it, you can use ! in front of the logical statement:

SE_CSVLinelist_filtered <- filter(SE_CSVLinelist_clean, 
 !where_case_travelled_1 %in% 
   c('Outside Canada','Outside province/territory of residence but within Canada'))

Regarding your original approach with -c(...), - is a unary operator that "performs arithmetic on numeric or complex vectors (or objects which can be coerced to them)" (from help("-")). Since you are dealing with a character vector that cannot be coerced to numeric or complex, you cannot use -.

"Use the new keyword if hiding was intended" warning

The parent function needs the virtual keyword, and the child function needs the override keyword in front of the function definition.

What is the difference between exit(0) and exit(1) in C?

exit(0) indicates that the program terminated without errors. exit(1) indicates that there were an error.

You can use different values other than 1 to differentiate between different kind of errors.

How ViewBag in ASP.NET MVC works

It's a dynamic object, meaning you can add properties to it in the controller, and read them later in the view, because you are essentially creating the object as you do, a feature of the dynamic type. See this MSDN article on dynamics. See this article on it's usage in relation to MVC.

If you wanted to use this for web forms, add a dynamic property to a base page class like so:

public class BasePage : Page

    public dynamic ViewBagProperty

Have all of your pages inherit from this. You should be able to, in your ASP.NET markup, do:

<%= ViewBagProperty.X %>

That should work. If not, there are ways to work around it.

Reading and displaying data from a .txt file

public class PassdataintoFile {

    public static void main(String[] args) throws IOException  {
        try {
            PrintWriter pw = new PrintWriter("C:/new/hello.txt", "UTF-8");
            PrintWriter pw1 = new PrintWriter("C:/new/hello.txt");
             pw1.println("Hi chinni");
             pw1.print("your succesfully entered text into file");
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
        BufferedReader br = new BufferedReader(new FileReader("C:/new/hello.txt"));
           String line;
           while((line = br.readLine())!= null)


Insertion Sort vs. Selection Sort

Insertion sort do not swap things. Even though it make use of a temp variable, The point of making use of temp var is when we found a value at an index to be less compared to the value to its previous index, we shift the greater value to the place of lesser value's index which would over write things. Then we use the temp var to be substituted at the previous index. Example: 10, 20, 30, 50, 40. iteration 1: 10, 20, 30, 50, 50. [temp = 40] iteration 2: 10,20, 30, 40(temp's value), 50. So, we just insert a value at the desired position from some variable.

But When we consider selection sort, We first find the index having lower value and swap that value with the value from first index and keep on repeatedly swapping till all the indices get sorted. This is exactly same as traditional swapping of two numbers. Example: 30, 20 ,10, 40, 50. Iteration 1: 10, 20, 30, 40, 50. Here temp var is used exclusively for swapping.

How to declare and add items to an array in Python?

Just for sake of completion, you can also do this:

array = []
array += [valueToBeInserted]

If it's a list of strings, this will also work:

array += 'string'

How do I create a round cornered UILabel on the iPhone?

You can make rounded border with width of border of any control in this way:-

CALayer * l1 = [lblName layer];
[l1 setMasksToBounds:YES];
[l1 setCornerRadius:5.0];

// You can even add a border
[l1 setBorderWidth:5.0];
[l1 setBorderColor:[[UIColor darkGrayColor] CGColor]];

Just replace lblName with your UILabel.

Note:- Don't forget to import <QuartzCore/QuartzCore.h>

How do I pass variables and data from PHP to JavaScript?

I usually use data-* attributes in HTML.

<div class="service-container" data-service="<?php echo $myService->getValue(); ?>">


    $(document).ready(function() {
        $('.service-container').each(function() {
            var container = $(this);
            var service ='service');

            // Variable "service" now contains the value of $myService->getValue();

This example uses jQuery, but it can be adapted for another library or vanilla JavaScript.

You can read more about the dataset property here:

Twitter Bootstrap onclick event on buttons-radio

I would use a change event not a click like this:

$('input[name="name-of-radio-group"]').change( function() {

Stretch child div height to fill parent that has dynamic height

Use display: flex to stretch your divs:

div#container {
    display: flex;

.content {
    margin-left: 10px;


How to compile for Windows on Linux with gcc/g++?

Suggested method gave me error on Ubuntu 16.04: E: Unable to locate package mingw32


To install this package on Ubuntu please use following:

sudo apt-get install mingw-w64

After install you can use it:


Please note!

For 64-bit use: x86_64-w64-mingw32-g++

For 32-bit use: i686-w64-mingw32-g++

Stop executing further code in Java

There are two way to stop current method/process :

  1. Throwing Exception.
  2. returnning the value even if it is void method.

Option : you can also kill the current thread to stop it.

For example :

public void onClick(){

    if(condition == true){
        throw new YourException();
    string.setText("This string should not change if condition = true");

How to print Unicode character in Python?

This fixes UTF-8 printing in python:

UTF8Writer = codecs.getwriter('utf8')
sys.stdout = UTF8Writer(sys.stdout)

Python reshape list to ndim array

You can specify the interpretation order of the axes using the order parameter:

np.reshape(arr, (2, -1), order='F')

unix sort descending order

The presence of the n option attached to the -k5 causes the global -r option to be ignored for that field. You have to specify both n and r at the same level (globally or locally).

sort -t $'\t' -k5,5rn


sort -rn -t $'\t' -k5,5

What is the largest possible heap size with a 64-bit JVM?

If you want to use 32-bit references, your heap is limited to 32 GB.

However, if you are willing to use 64-bit references, the size is likely to be limited by your OS, just as it is with 32-bit JVM. e.g. on Windows 32-bit this is 1.2 to 1.5 GB.

Note: you will want your JVM heap to fit into main memory, ideally inside one NUMA region. That's about 1 TB on the bigger machines. If your JVM spans NUMA regions the memory access and the GC in particular will take much longer. If your JVM heap start swapping it might take hours to GC, or even make your machine unusable as it thrashes the swap drive.

Note: You can access large direct memory and memory mapped sizes even if you use 32-bit references in your heap. i.e. use well above 32 GB.

Compressed oops in the Hotspot JVM

Compressed oops represent managed pointers (in many but not all places in the JVM) as 32-bit values which must be scaled by a factor of 8 and added to a 64-bit base address to find the object they refer to. This allows applications to address up to four billion objects (not bytes), or a heap size of up to about 32Gb. At the same time, data structure compactness is competitive with ILP32 mode.

Hadoop/Hive : Loading data from .csv on a local machine

For csv file formate data will be in below format

"column1", "column2","column3","column4"

And if we will use field terminated by ',' then each column will get values like below.

"column1"    "column2"     "column3"     "column4"

also if any of the column value has comma as value then it will not work at all .

So the correct way to create a table would be by using OpenCSVSerde

create table tableName (column1 datatype, column2 datatype , column3 datatype , column4 datatype)

coercing to Unicode: need string or buffer, NoneType found when rendering in django admin

Replace the earlier function with the provided one. The simplest solution is:

def __unicode__(self):

    return unicode(self.nom_du_site)

Return list from async/await method

You need to correct your code to wait for the list to be downloaded:

List<Item> list = await GetListAsync();

Also, make sure that the method, where this code is located, has async modifier.

The reason why you get this error is that GetListAsync method returns a Task<T> which is not a completed result. As your list is downloaded asynchronously (because of Task.Run()) you need to "extract" the value from the task using the await keyword.

If you remove Task.Run(), you list will be downloaded synchronously and you don't need to use Task, async or await.

One more suggestion: you don't need to await in GetListAsync method if the only thing you do is just delegating the operation to a different thread, so you can shorten your code to the following:

private Task<List<Item>> GetListAsync(){
    return Task.Run(() => manager.GetList());

Python one-line "for" expression

If you really only need to add the items in one array to another, the '+' operator is already overloaded to do that, incidentally:

a1 = [1,2,3,4,5]
a2 = [6,7,8,9]
a1 + a2
--> [1, 2, 3, 4, 5, 6, 7, 8, 9]

CSS: How to align vertically a "label" and "input" inside a "div"?

a more modern approach would be to use css flex-box.

div {_x000D_
  height: 50px;_x000D_
  background: grey;_x000D_
  display: flex;_x000D_
  align-items: center_x000D_
  <label for='name'>Name:</label>_x000D_
  <input type='text' id='name' />_x000D_

a more complex example... if you have multible elements in the flex flow, you can use align-self to align single elements differently to the specified align...

div {_x000D_
  display: flex;_x000D_
  align-items: center_x000D_
* {_x000D_
  margin: 10px_x000D_
label {_x000D_
  align-self: flex-start_x000D_
  <img src="" />_x000D_
  <input placeholder="Text" type="text" />_x000D_

its also super easy to center horizontally and vertically:

div {_x000D_
  background: grey;_x000D_
  display: flex;_x000D_
  align-items: center;_x000D_
  <label for='name'>Name:</label>_x000D_
  <input type='text' id='name' />_x000D_

jQuery.each - Getting li elements inside an ul

First I think you need to fix your lists, as the first node of a <ul> must be a <li> (stackoverflow ref). Once that is setup you can do this:

// note this array has outer scope
var phrases = [];

        // this is inner scope, in reference to the .phrase element
        var phrase = '';
            // cache jquery var
            var current = $(this);
            // check if our current li has children (sub elements)
            // if it does, skip it
            // ps, you can work with this by seeing if the first child
            // is a UL with blank inside and odd your custom BLANK text
            if(current.children().size() > 0) {return true;}
            // add current text to our current phrase
            phrase += current.text();
        // now that our current phrase is completely build we add it to our outer array
    // note the comma in the alert shows separate phrases

Working jsfiddle.

One thing is if you get the .text() of an upper level li you will get all sub level text with it.

Keeping an array will allow for many multiple phrases to be extracted.


This should work better with an empty UL with no LI:

// outer scope
var phrases = [];

    // inner scope
    var phrase = '';
        // cache jquery object
        var current = $(this);
        // check for sub levels
        if(current.children().size() > 0) {
            // check is sublevel is just empty UL
            var emptyULtest = current.children().eq(0); 
            if('ul') && $.trim(emptyULtest.text())==""){
                phrase += ' -BLANK- '; //custom blank text
                return true;   
            } else {
             // else it is an actual sublevel with li's
             return true;   
        // if it gets to here it is actual li
        phrase += current.text();
// note the comma to separate multiple phrases

How to make sql-mode="NO_ENGINE_SUBSTITUTION" permanent in MySQL my.cnf

Woks fine for me on ubuntu 16.04. path: /etc/mysql/mysql.cnf

and paste that

# * Basic Settings

Cell spacing in UICollectionView

Swift 3 Version

Simply create a UICollectionViewFlowLayout subclass and paste this method.

override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        guard let answer = super.layoutAttributesForElements(in: rect) else { return nil }

        for i in 1..<answer.count {
            let currentAttributes = answer[i]
            let previousAttributes = answer[i - 1]

            let maximumSpacing: CGFloat = 8
            let origin = previousAttributes.frame.maxX

            if (origin + maximumSpacing + currentAttributes.frame.size.width < self.collectionViewContentSize.width && currentAttributes.frame.origin.x > previousAttributes.frame.origin.x) {
                var frame = currentAttributes.frame
                frame.origin.x = origin + maximumSpacing
                currentAttributes.frame = frame

        return answer

UL list style not applying

All you have to do is add this class to your css.

.ul-no-style { list-style: none; padding: 0; margin: 0; }

Including the padding and margin set at 0.

Is there a simple, elegant way to define singletons?

The module approach works well. If I absolutely need a singleton I prefer the Metaclass approach.

class Singleton(type):
    def __init__(cls, name, bases, dict):
        super(Singleton, cls).__init__(name, bases, dict)
        cls.instance = None 

    def __call__(cls,*args,**kw):
        if cls.instance is None:
            cls.instance = super(Singleton, cls).__call__(*args, **kw)
        return cls.instance

class MyClass(object):
    __metaclass__ = Singleton

Decompile an APK, modify it and then recompile it

I know this question is answered still, I would like to pass an information how to get source code from apk with out dexjar.

There is an online decompiler for android apks

  1. Upload apk from local machine
  2. Wait some moments
  3. Download source code in zip format

I don't know how reliable is this.

@darkheir Answer is the manual way to do decompile apk. It helps us to understand different phases in Apk creation.

Once you have source code , follow the step mentioned in the accepted answer

Report so many ads on this links Another online Apk De-compiler @Andrew Rukin :

Still worth. Hats Off to creators.

How to use function srand() with time.h?

If you chose to srand, it is a good idea to then call rand() at least once before you use it, because it is a kind of horrible primitive psuedo-random generator. See Stack Overflow question Why does rand() % 7 always return 0?.

//Now use rand()

If available, either random or arc4rand would be better.

How can I generate Javadoc comments in Eclipse?

At a place where you want javadoc, type in /**<NEWLINE> and it will create the template.

Hidden features of Windows batch files

This batch file works both with simple files as well as directories as command line parameters (you can mix them in any order). The loop runs the command ('echo' in this example) on any specified file, if a parameter is a directory it runs the command recursively on each file in it.

@echo off
for /f "delims=" %%f in ('dir %* /a-d /b /s') do echo %%f

How to make PopUp window in java

Check out Swing Dialogs (mainly focused on JOptionPane, as mentioned by @mcfinnigan).

Problems with entering Git commit message with Vim

If it is VIM for Windows, you can do the following:

  • enter your message following the presented guidelines
  • press Esc to make sure you are out of the insert mode
  • then type :wqEnter or ZZ.

Note that in VIM there are often several ways to do one thing. Here there is a slight difference though. :wqEnter always writes the current file before closing it, while ZZ, :xEnter, :xiEnter, :xitEnter, :exiEnter and :exitEnter only write it if the document is modified.
All these synonyms just have different numbers of keypresses.

How can apply multiple background color to one div

Sorry for misunderstanding, from what I understood you want your DIV to have three different colors with different heights. This is the output of my code:


If this is what you want try this code:

div {_x000D_
    height: 100px;_x000D_
    position: relative;_x000D_
.c {_x000D_
    background: blue; /* Old browsers */_x000D_
    content: '';_x000D_
    position: absolute;_x000D_
    background: yellow;_x000D_
    content: '';_x000D_
    position: absolute;_x000D_
    background: green;_x000D_
<div class="c"></div>

dd: How to calculate optimal blocksize?

This is totally system dependent. You should experiment to find the optimum solution. Try starting with bs=8388608. (As Hitachi HDDs seems to have 8MB cache.)

Could not load file or assembly for Oracle.DataAccess in .NET

Try the following: In Visual Studio, go to Tools/Options....Projects and Solutions...Web Projects... Make sure that 64 bit version of IIS Express checkbox is checked off.

Convert Json string to Json object in Swift 4

I used below code and it's working fine for me. :

let jsonText = "{\"userName\":\"Bhavsang\"}"
var dictonary:NSDictionary?
if let data = jsonText.dataUsingEncoding(NSUTF8StringEncoding) {
     do {
            dictonary =  try NSJSONSerialization.JSONObjectWithData(data, options: [.allowFragments]) as? [String:AnyObject]
            if let myDictionary = dictonary
                  print(" User name is: \(myDictionary["userName"]!)")
            } catch let error as NSError {

Fatal error: Call to a member function bind_param() on boolean

Any time you get the...

"Fatal error: Call to a member function bind_param() on boolean" is likely because there is an issue with your query. The prepare() might return FALSE (a Boolean), but this generic failure message doesn't leave you much in the way of clues. How do you find out what is wrong with your query? You ask!

First of all, make sure error reporting is turned on and visible: add these two lines to the top of your file(s) right after your opening <?php tag:

ini_set('display_errors', 1);

If your error reporting has been set in the php.ini you won't have to worry about this. Just make sure you handle errors gracefully and never reveal the true cause of any issues to your users. Revealing the true cause to the public can be a gold engraved invitation for those wanting to harm your sites and servers. If you do not want to send errors to the browser you can always monitor your web server error logs. Log locations will vary from server to server e.g., on Ubuntu the error log is typically located at /var/log/apache2/error.log. If you're examining error logs in a Linux environment you can use tail -f /path/to/log in a console window to see errors as they occur in real-time....or as you make them.

Once you're squared away on standard error reporting adding error checking on your database connection and queries will give you much more detail about the problems going on. Have a look at this example where the column name is incorrect. First, the code which returns the generic fatal error message:

$sql = "SELECT `foo` FROM `weird_words` WHERE `definition` = ?";
$query = $mysqli->prepare($sql)); // assuming $mysqli is the connection
$query->bind_param('s', $definition);

The error is generic and not very helpful to you in solving what is going on.

With a couple of more lines of code you can get very detailed information which you can use to solve the issue immediately. Check the prepare() statement for truthiness and if it is good you can proceed on to binding and executing.

$sql = "SELECT `foo` FROM `weird_words` WHERE `definition` = ?";
if($query = $mysqli->prepare($sql)) { // assuming $mysqli is the connection
    $query->bind_param('s', $definition);
    // any additional code you need would go here.
} else {
    $error = $mysqli->errno . ' ' . $mysqli->error;
    echo $error; // 1054 Unknown column 'foo' in 'field list'

If something is wrong you can spit out an error message which takes you directly to the issue. In this case there is no foo column in the table, solving the problem is trivial.

If you choose, you can include this checking in a function or class and extend it by handling the errors gracefully as mentioned previously.

Leave menu bar fixed on top when scrolled

you may want to add:


to trigger the scroll event when you reload an already scrolled page. Otherwise you might get your menu out of position.

        $(window).bind('scroll', function () {
            var pixels = 600; //number of pixels before modifying styles
            if ($(window).scrollTop() > pixels) {
            } else {

What's the best UI for entering date of birth?

As perhaps one of the older people here, and born late in the month, I find drop-down menus for birthdates to be frustrating. I typically have to scroll down on two drop-down menus, and that's awkward. I'd much rather type it in.

If you can have a control designed so that it can either accept drop-down menus or be typed into, and make it clear both work, that would be excellent.

Accessing value inside nested dictionaries

My implementation:

def get_nested(data, *args):
    if args and data:
        element  = args[0]
        if element:
            value = data.get(element)
            return value if len(args) == 1 else get_nested(value, *args[1:])

Example usage:

>>> dct={"foo":{"bar":{"one":1, "two":2}, "misc":[1,2,3]}, "foo2":123}
>>> get_nested(dct, "foo", "bar", "one")
>>> get_nested(dct, "foo", "bar", "two")
>>> get_nested(dct, "foo", "misc")
[1, 2, 3]
>>> get_nested(dct, "foo", "missing")

There are no exceptions raised in case a key is missing, None value is returned in that case.

Spring Boot default H2 jdbc connection (and H2 console)

A similar answer with Step by Step guide.

  1. Add Developer tools dependency to your pom.xml or build.gradle




dependencies {
  1. Access the db from http://localhost:8080/h2-console/
  2. Specify jdbc:h2:mem:testdb as JDBC URL
  3. You should see the entity you specified in your project as a table.

invalid new-expression of abstract class type

for others scratching their heads, I came across this error because I had innapropriately const-qualified one of the arguments to a method in a base class, so the derived class member functions were not over-riding it. so make sure you don't have something like

class Base 
      virtual void foo(int a, const int b) = 0;
class D: public Base 
     void foo(int a, int b){};

Servlet Mapping using web.xml

It allows servlets to have multiple servlet mappings:


It allows filters to be mapped on the particular servlet:


Your proposal would support neither of them. Note that the web.xml is read and parsed only once during application's startup, not on every HTTP request as you seem to think.

Since Servlet 3.0, there's the @WebServlet annotation which minimizes this boilerplate:

public class Servlet1 extends HttpServlet {

See also:

Creating a UIImage from a UIColor to use as a background image for UIButton

CGContextSetFillColorWithColor(context,[[UIColor colorWithRed:(255/255.f) green:(0/255.f) blue: (0/255.f) alpha:1] CGColor]);

Why does Vim save files with a ~ extension?

To turn off those files, just add these lines to .vimrc (vim configuration file on unix based OS):

set nobackup       #no backup files
set nowritebackup  #only in case you don't want a backup file while editing
set noswapfile     #no swap files

How to make a checkbox checked with jQuery?



SHA-256 or MD5 for file integrity

Both SHA256 and MDA5 are hashing algorithms. They take your input data, in this case your file, and output a 256/128-bit number. This number is a checksum. There is no encryption taking place because an infinite number of inputs can result in the same hash value, although in reality collisions are rare.

SHA256 takes somewhat more time to calculate than MD5, according to this answer.

Offhand, I'd say that MD5 would be probably be suitable for what you need.

How do I access call log for android?

This is for accessing phone call history:

As of Jellybean (4.1) you need the following permission:
<uses-permission android:name="android.permission.READ_CALL_LOG" />


 Uri allCalls = Uri.parse("content://call_log/calls");
 Cursor c = managedQuery(allCalls, null, null, null, null);

String num= c.getString(c.getColumnIndex(CallLog.Calls.NUMBER));// for  number
String name= c.getString(c.getColumnIndex(CallLog.Calls.CACHED_NAME));// for name
String duration = c.getString(c.getColumnIndex(CallLog.Calls.DURATION));// for duration
int type = Integer.parseInt(c.getString(c.getColumnIndex(CallLog.Calls.TYPE)));// for call type, Incoming or out going.

How to get all selected values of a multiple select box?

My template helper looks like this:

 'submit #update': function(event) {
    var obj_opts =; //returns HTMLCollection
    var array_opts = Object.values(obj_opts);  //convert to array
    var stray => o.text ); //to filter your bits: text, value or selected
    //do stuff

to_string is not a member of std, says g++ (mingw)

As suggested this may be an issue with your compiler version.

Try using the following code to convert a long to std::string:

#include <sstream>
#include <string>
#include <iostream>

int main() {
    std::ostringstream ss;
    long num = 123456;
    ss << num;
    std::cout << ss.str() << std::endl;

Multiple radio button groups in one form

To create a group of inputs you can create a custom html element

window.customElements.define('radio-group', RadioGroup);

to keep selected option in each group, you need to add name attribute to inputs in group, if you not add it then all is one group.

Scaling an image to fit on canvas

Provide the source image (img) size as the first rectangle:

ctx.drawImage(img, 0, 0, img.width,    img.height,     // source rectangle
                   0, 0, canvas.width, canvas.height); // destination rectangle

The second rectangle will be the destination size (what source rectangle will be scaled to).

Update 2016/6: For aspect ratio and positioning (ala CSS' "cover" method), check out:
Simulation background-size: cover in canvas

Pandas split column of lists into multiple columns

list comprehension

simple implementation with list comprehension ( my favorite)

df = pd.DataFrame([pd.Series(x) for x in df.teams])
df.columns = ['team_{}'.format(x+1) for x in df.columns]

timing on output:

CPU times: user 0 ns, sys: 0 ns, total: 0 ns
Wall time: 2.71 ms


team_1  team_2
0   SF  NYG
1   SF  NYG
2   SF  NYG
3   SF  NYG
4   SF  NYG
5   SF  NYG
6   SF  NYG

What are and

reference : -- a user input file to automake -- a user input file to autoconf

autoconf generates configure from

automake gererates from

configure generates Makefile from

For ex:

$] sudo autoconf
configure ... 
$] sudo ./configure

How to print React component on click of a button?

First want to credit @emil-ingerslev for an awesome answer. I tested it and it worked perfectly. There were two things however I wanted to improve.

  1. I didn't like having to already have <iframe id="ifmcontentstoprint" style="height: 0px; width: 0px; position: absolute"></iframe> already in the dom tree.
  2. I wanted to create a way to make it reusable.

I hope this makes others happy and saves a few minutes of life. Now go take those extra minutes and do something nice for someone.

function printPartOfPage(elementId, uniqueIframeId){
    const content = document.getElementById(elementId)
    let pri
    if (document.getElementById(uniqueIframeId)) {
        pri = document.getElementById(uniqueIframeId).contentWindow
    } else {
        const iframe = document.createElement('iframe')
        iframe.setAttribute('title', uniqueIframeId)
        iframe.setAttribute('id', uniqueIframeId)
        iframe.setAttribute('style', 'height: 0px; width: 0px; position: absolute;')
        pri = iframe.contentWindow

EDIT 2019-7-23: After using this more, this does have the downside that it doesn't perfectly render react components. This worked for me when the styling was inline but not when handled by styled-components or some other situations. If I come up with a foolproof method I will update.

Iterating through a list to render multiple widgets in Flutter?

You can use ListView to render a list of items. But if you don't want to use ListView, you can create a method which returns a list of Widgets (Texts in your case) like below:

var list = ["one", "two", "three", "four"];

    Widget build(BuildContext context) {
      return new MaterialApp(
          home: new Scaffold(
        appBar: new AppBar(
          title: new Text('List Test'),
        body: new Center(
          child: new Column( // Or Row or whatever :)
            children: createChildrenTexts(),

     List<Text> createChildrenTexts() {
    /// Method 1
//    List<Text> childrenTexts = List<Text>();
//    for (String name in list) {
//      childrenTexts.add(new Text(name, style: new TextStyle(color:,));
//    }
//    return childrenTexts;

    /// Method 2
    return => Text(text, style: TextStyle(color:,)).toList();

Python string.replace regular expression

str.replace() v2|v3 does not recognize regular expressions.

To perform a substitution using a regular expression, use re.sub() v2|v3.

For example:

import re

line = re.sub(
           "interfaceOpDataFile %s" % fileIn, 

In a loop, it would be better to compile the regular expression first:

import re

regex = re.compile(r"^.*interfaceOpDataFile.*$", re.IGNORECASE)
for line in some_file:
    line = regex.sub("interfaceOpDataFile %s" % fileIn, line)
    # do something with the updated line

Makefile ifeq logical or

You can introduce another variable. It doesnt consolidate both checks, but it at least avoids having to put the body in twice:

do_it = 
ifeq ($(GCC_MINOR), 4)
    do_it = yes
ifeq ($(GCC_MINOR), 5)
    do_it = yes
ifdef do_it
    CFLAGS += -fno-strict-overflow

How can I use numpy.correlate to do autocorrelation?

An alternative to numpy.correlate is available in statsmodels.tsa.stattools.acf(). This yields a continuously decreasing autocorrelation function like the one described by OP. Implementing it is fairly simple:

from statsmodels.tsa import stattools
# x = 1-D array
# Yield normalized autocorrelation function of number lags
autocorr = stattools.acf( x )

# Get autocorrelation coefficient at lag = 1
autocorr_coeff = autocorr[1]

The default behavior is to stop at 40 nlags, but this can be adjusted with the nlag= option for your specific application. There is a citation at the bottom of the page for the statistics behind the function.

/lib/ bad ELF interpreter: No such file or directory

I had the same issue, the following commands can resolve:

sudo yum install  glibc-common glibc  (mutual dependency)
sudo yum install  glibc.i686  (the missing version)

Running Git through Cygwin from Windows

I confirm that git and msysgit can coexist on the same computer, as mentioned in "Which GIT version to use cygwin or msysGit or both?".

  1. Git for Windows (msysgit) will run in its own shell (dos with git-cmd.bat or bash with Git Bash.vbs)
    Update 2016: msysgit is obsolete, and the new Git for Windows now uses msys2

  2. Git on Cygwin, after installing its package, will run in its own cygwin bash shell.

git package selection on Cygwin

  1. Finally, since Q3 2016 and the "Windows 10 anniversary update", you can use Git in a bash (an actual Ubuntu(!) bash).

In there, you can do a sudo apt-get install git-core and start using git on project-sources present either on the WSL container's "native" file-system (see below), or in the hosting Windows's file-system through the /mnt/c/..., /mnt/d/... directory hierarchies.

Specifically for the Bash on Windows or WSL (Windows Subsystem for Linux):

  • It is a light-weight virtualization container (technically, a "Drawbridge" pico-process,
  • hosting an unmodified "headless" Linux distribution (i.e. Ubuntu minus the kernel),
  • which can execute terminal-based commands (and even X-server client apps if an X-server for Windows is installed),
  • with emulated access to the Windows file-system (meaning that, apart from reduced performance, encodings for files in DrvFs emulated file-system may not behave the same as files on the native VolFs file-system).

How do I pass parameters to a jar file at the time of execution?

Incase arguments have spaces in it, you can pass like shown below.

java -jar myjar.jar 'first argument' 'second argument'

Creating the checkbox dynamically using JavaScript?

   /* worked for me  */
     <div id="divid"> </div>
     <script type="text/javascript">
         var hold = document.getElementById("divid");
         var checkbox = document.createElement('input');
         checkbox.type = "checkbox"; = "chkbox1"; = "cbid";
         var label = document.createElement('label');
         var tn = document.createTextNode("Not A RoBot");

How can I sort a List alphabetically?

Unless you are sorting strings in an accent-free English only, you probably want to use a Collator. It will correctly sort diacritical marks, can ignore case and other language-specific stuff:

Collections.sort(countries, Collator.getInstance(new Locale(languageCode)));

You can set the collator strength, see the javadoc.

Here is an example for Slovak where Š should go after S, but in UTF Š is somewhere after Z:

List<String> countries = Arrays.asList("Slovensko", "Švédsko", "Turecko");

System.out.println(countries); // outputs [Slovensko, Turecko, Švédsko]

Collections.sort(countries, Collator.getInstance(new Locale("sk")));
System.out.println(countries); // outputs [Slovensko, Švédsko, Turecko]

ExecutorService that interrupts tasks after a timeout

How about using the ExecutorService.shutDownNow() method as described in It seems to be the simplest solution.

Read the current full URL with React?

Just to add a little further documentation to this page - I have been struggling with this problem for a while.

As said above, the easiest way to get the URL is via window.location.href.

we can then extract parts of the URL through vanilla Javascript by using let urlElements = window.location.href.split('/')

We would then console.log(urlElements) to see the Array of elements produced by calling .split() on the URL.

Once you have found which index in the array you want to access, you can then assigned this to a variable

let urlElelement = (urlElements[0])

And now you can use the value of urlElement, which will be the specific part of your URL, wherever you want.

React - how to pass state to another component

Move all of your state and your handleClick function from Header to your MainWrapper component.

Then pass values as props to all components that need to share this functionality.

class MainWrapper extends React.Component {
    constructor() {
        this.state = {
            sidbarPushCollapsed: false,
            profileCollapsed: false
        this.handleClick = this.handleClick.bind(this);
    handleClick() {
            sidbarPushCollapsed: !this.state.sidbarPushCollapsed,
            profileCollapsed: !this.state.profileCollapsed

    render() {
        return (
               profileCollapsed={this.state.profileCollapsed} />

Then in your Header's render() method, you'd use this.props:

<button type="button" id="sidbarPush" onClick={this.props.handleClick} profile={this.props.profileCollapsed}>

How to I say Is Not Null in VBA

Use Not IsNull(Fields!W_O_Count.Value)

android - listview get item view by position

You can get only visible View from ListView because row views in ListView are reuseable. If you use mListView.getChildAt(0) you get first visible view. This view is associated with item from adapter at position mListView.getFirstVisiblePosition().

PHP page redirect

I would probably set the message as a session variable, redirect the user to another page which displays the message and destroy the session.

Netbeans - Error: Could not find or load main class

You can :

  • RightClick on project node and go to Set configuration
  • Select the main class for your application.
  • Then clean and build.

Even if the above steps don't work for you then then delete the Netbeans cache by deleting the (index) folder


What is the difference between loose coupling and tight coupling in the object oriented paradigm?

Explanation without any code

Summary Example:

The Hat is "loosely coupled" to the body. This means you can easily take the hat off without making any changes to the person/body. When you can do that then you have "loose coupling". See below for elaboration.

The Hat is "loosely coupled" to the body. This means you can easily take then hat off without making any changes to the the person/body. Picture Attribution:

Tight coupling (Detailed Example)

Skin - tight coupling

Think of your skin. It's stuck to your body. It fits like a glove. But what if you wanted to change your skin colour from say white to black? Can you imagine just how painful it would be to peel off your skin, dye it, and then to paste it back on etc? Changing your skin is difficult because it is tightly coupled to your body. You just can't make changes easily. You would have to fundamentally redesign a human being in order to make this possible.

  • Key Point #1: In other words, if you want to change the skin, you would also HAVE TO change the design of your body as well because the two are joined together - they are tightly coupled.

God was not a good object oriented programmer.

Loose coupling (Detailed Example)

Now think of getting dressed in the morning. You don't like blue? No problems: you can put a red shirt on instead. You can do this easily and effortlessly because the shirt is not really connected to your body the same way as your skin. The shirt doesn't know or care about what body it is going on. In other words, you can change your clothes, without really changing your body.

  • That's key point #2. If you change your shirt, then you are not forced to change your body - when you can do that, then you have loose coupling. When you can't do that, then you have tight coupling.

That's the basic concept in a nutshell.

Why is all of this important?

It's important because software changes all the time. Generally speaking you want to be able to easily modify your code, without changing your code. I know that sounds like an oxymoron, but please bear with me.

Practical Examples of Coupling when Designing Software

  • CSV/JSON/DB Examples: If somebody wants their output in a CSV file rather than JSON etc., or if you want to switch from MySQL to PostGreSQL you should be able to make those changes extremely easily in your code, without having to rewrite the entire class etc. In other words, you do not want to tightly couple your application with a specific database implementation (e.g. Mysql) or to a particular output (e.g. CSV files). Because, as is inevitable in software, changes will come. When they do come, it's much easier if your parts of your code are loosely coupled. Or if you're using AWS and they start charging too much because of market dominance, you should be able to somewhat easily switch to Google or Azure etc.

Practical Example in Manufacturing - Car Parts:

Another example to reinforce coupling:

If somebody wants their car in black, you shouldn't have to redesign the entire car in order to do that. A car and its spare parts would be a perfect example of a loosely coupled architecture. If you want to replace your engine with a better one, you should be able to simply remove your engine without too much effort and swap it for a better one. If your car only works with Rolls Royce 1234 Engines and no other engines - then your car will is tightly coupled to that engine (Rolls Royce 1234).

Some amount of coupling is going to happen, but you should work to minimise it as much as you can. Why? Because when requirements change we should still be able to deliver good quality software, very quickly and we are aided in that goal by loose coupling.


In short, loose coupling makes code easier to change. The answers above provide some code which is worth reading at this point.

Picture Attribution.

Adding VirtualHost fails: Access Forbidden Error 403 (XAMPP) (Windows 7)

Above suggestions didn't worked for me. I got it running on my windows, using inspiration from

For Http inside httpd-vhosts.conf

<Directory "D:/Projects">       
AllowOverride All
Require all granted

<VirtualHost *:80>
DocumentRoot "D:/Projects/letzgrow"

For using Https (Open SSL) inside httpd-ssl.conf

<Directory "D:/Projects">       
AllowOverride All
Require all granted

<VirtualHost *:443>
DocumentRoot "D:/Projects/letzgrow"

Hope it helps someone !!

Calculate age based on date of birth

declare @dateOfBirth date select @dateOfBirth = '2000-01-01'

SELECT datediff(YEAR,@dateOfBirth,getdate()) as Age

Laravel 5 - artisan seed [ReflectionException] Class SongsTableSeeder does not exist

Do not forgot that the composer dump-autoload works in relation with the autoload / classmap section of composer.json. Take care about that if you need to change seeders directory or use multiple directories to store seeders.

"autoload": {
    "classmap": [

delete all from table

This is deletes the table table_name.

Replace it with the name of the table, which shall be deleted.

DELETE FROM table_name;

jQuery.parseJSON throws “Invalid JSON” error due to escaped single quote in JSON

I was trying to save a JSON object from a XHR request into a HTML5 data-* attribute. I tried many of above solutions with no success.

What I finally end up doing was replacing the single quote ' with it code &#39; using a regex after the stringify() method call the following way:

var productToString = JSON.stringify(productObject);
var quoteReplaced = productToString.replace(/'/g, "&#39;");
var anchor = '<a data-product=\'' + quoteReplaced + '\' href=\'#\'>' + + '</a>';
// Here you can use the "anchor" variable to update your DOM element.

Get last n lines of a file, similar to tail

If reading the whole file is acceptable then use a deque.

from collections import deque
deque(f, maxlen=n)

Prior to 2.6, deques didn't have a maxlen option, but it's easy enough to implement.

import itertools
def maxque(items, size):
    items = iter(items)
    q = deque(itertools.islice(items, size))
    for item in items:
        del q[0]
    return q

If it's a requirement to read the file from the end, then use a gallop (a.k.a exponential) search.

def tail(f, n):
    assert n >= 0
    pos, lines = n+1, []
    while len(lines) <= n:
  , 2)
        except IOError:
            lines = list(f)
        pos *= 2
    return lines[-n:]

Getting pids from ps -ef |grep keyword

This is available on linux: pidof keyword

Difference between @Mock and @InjectMocks

Many people have given a great explanation here about @Mock vs @InjectMocks. I like it, but I think our tests and application should be written in such a way that we shouldn't need to use @InjectMocks.

Reference for further reading with examples:

undefined reference to `std::ios_base::Init::Init()'

You can resolve this in several ways:

  • Use g++ in stead of gcc: g++ -g -o MatSim MatSim.cpp
  • Add -lstdc++: gcc -g -o MatSim MatSim.cpp -lstdc++
  • Replace <string.h> by <string>

This is a linker problem, not a compiler issue. The same problem is covered in the question iostream linker error – it explains what is going on.

Excel: Searching for multiple terms in a cell

Another way


Also, if you keep a list of values in, say A1 to A3, then you can use


The wildcards are not necessary at all in the Search() function, since Search() returns the position of the found string.

How to find the length of an array in shell?

In the Fish Shell the length of an array can be found with:

$ set a 1 2 3 4
$ count $a

Can't find @Nullable inside javax.annotation.*

You need to include a jar that this class exists in. You can find it here

If using Maven, you can add the following dependency declaration:


and for Gradle:

dependencies {
  testImplementation ''

Filter data.frame rows by a logical condition

This worked like magic for me.

celltype_hesc_bool = expr['cell_type'] == 'hesc'

expr_celltype_hesc = expr[celltype_hesc]

Check this blog post

php string to int

What do you even want the result to be? 888888? If so, just remove the spaces with str_replace, then convert.

How to check if a number is a power of 2

This program in java returns "true" if number is a power of 2 and returns "false" if its not a power of 2

// To check if the given number is power of 2

import java.util.Scanner;

public class PowerOfTwo {
    int n;
    void solve() {
        while(true) {
//          To eleminate the odd numbers
            if((n%2)!= 0){
//  Tracing the number back till 2
            n = n/2;
//  2/2 gives one so condition should be 1
            if(n == 1) {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in = new Scanner(;
        PowerOfTwo obj = new PowerOfTwo();
        obj.n = in.nextInt();




Numpy how to iterate over columns of array?

Alternatively, you can use enumerate. It gives you the column number and the column values as well.

for num, column in enumerate(array.T):
    some_function(column) # column: Gives you the column value as asked in the question
    some_function(num) # num: Gives you the column number 

Sorting rows in a data table

//Hope This will help you..

        DataTable table = new DataTable();
        //DataRow[] rowArray = dataTable.Select();
        table = dataTable.Clone();
        for (int i = dataTable.Rows.Count - 1; i >= 0; i--)
        return table;

System.Net.WebException: The operation has timed out

Close/dispose your WebResponse object.

An unhandled exception was generated during the execution of the current web request

As far as I understand, you have more than one form tag in your web page that causes the problem. Make sure you have only one server-side form tag for each page.

CSS: Hover one element, effect for multiple elements?

You'd need to use JavaScript to accomplish this, I think.



Adjust the values and element id's accordingly :)

How to upgrade OpenSSL in CentOS 6.5 / Linux / Unix from source?

My approach was:

openssl version
OpenSSL 1.0.1e 11 Feb 2013

tar xzf openssl-1.0.2a.tar.gz
cd openssl-1.0.2a
patch -Np1 -i ../openssl-1.0.2a-fix_parallel_build-1.patch
./config --prefix=/usr --openssldir=/etc/ssl --libdir=lib shared zlib-dynamic
make install

openssl version
OpenSSL 1.0.2a 19 Mar 2015 

How to delete only the content of file in python

How to delete only the content of file in python

There is several ways of set the logical size of a file to 0, depending how you access that file:

To empty an open file:

def deleteContent(pfile):

To empty a open file whose file descriptor is known:

def deleteContent(fd):
    os.ftruncate(fd, 0)
    os.lseek(fd, 0, os.SEEK_SET)

To empty a closed file (whose name is known)

def deleteContent(fName):
    with open(fName, "w"):

I have a temporary file with some content [...] I need to reuse that file

That being said, in the general case it is probably not efficient nor desirable to reuse a temporary file. Unless you have very specific needs, you should think about using tempfile.TemporaryFile and a context manager to almost transparently create/use/delete your temporary files:

import tempfile

with tempfile.TemporaryFile() as temp:
     # do whatever you want with `temp`

# <- `tempfile` guarantees the file being both closed *and* deleted
#     on exit of the context manager

Update multiple values in a single statement

Have you tried with a sub-query for every field:

    TotalX = (SELECT SUM(X) from DetailTbl where DetailTbl.MasterID = MasterTbl.ID),
    TotalY = (SELECT SUM(Y) from DetailTbl where DetailTbl.MasterID = MasterTbl.ID),
    TotalZ = (SELECT SUM(Z) from DetailTbl where DetailTbl.MasterID = MasterTbl.ID)

how to show calendar on text box click in html

What you need is a jQuery UI Datepicker

Check out the demo and the source code.

Python: SyntaxError: keyword can't be an expression

sum.up is not a valid keyword argument name. Keyword arguments must be valid identifiers. You should look in the documentation of the library you are using how this argument really is called – maybe sum_up?

How to get all checked checkboxes

In IE9+, Chrome or Firefox you can do:

var checkedBoxes = document.querySelectorAll('input[name=mycheckboxes]:checked');

Find an object in array?


Check if the element exists

if array.contains(where: {$ == "foo"}) {
   // it exists, do something
} else {
   //item could not be found

Get the element

if let foo = array.first(where: {$ == "foo"}) {
   // do something with foo
} else {
   // item could not be found

Get the element and its offset

if let foo = array.enumerated().first(where: {$ == "foo"}) {
   // do something with foo.offset and foo.element
} else {
   // item could not be found

Get the offset

if let fooOffset = array.firstIndex(where: {$ == "foo"}) {
    // do something with fooOffset
} else {
    // item could not be found

How to use the TextWatcher class in Android?

    public class Test extends AppCompatActivity {

    EditText firstEditText;
    EditText secondEditText;

    protected void onCreate(@Nullable Bundle savedInstanceState) {
        firstEditText = (EditText)findViewById(;
        secondEditText = (EditText)findViewById(;

        firstEditText.addTextChangedListener(new EditTextListener());


    private class EditTextListener implements TextWatcher {

        public void beforeTextChanged(CharSequence s, int start, int count, int after) {


        public void onTextChanged(CharSequence s, int start, int before, int count) {

        public void afterTextChanged(Editable s) {

How to update attributes without validation

All the validation from model are skipped when we use validate: false

user = false)

Regular Expressions and negating a whole character group

Yes its called negative lookahead. It goes like this - (?!regex here). So abc(?!def) will match abc not followed by def. So it'll match abce, abc, abck, etc.

Similarly there is positive lookahead - (?=regex here). So abc(?=def) will match abc followed by def.

There are also negative and positive lookbehind - (?<!regex here) and (?<=regex here) respectively

One point to note is that the negative lookahead is zero-width. That is, it does not count as having taken any space.

So it may look like a(?=b)c will match "abc" but it won't. It will match 'a', then the positive lookahead with 'b' but it won't move forward into the string. Then it will try to match the 'c' with 'b' which won't work. Similarly ^a(?=b)b$ will match 'ab' and not 'abb' because the lookarounds are zero-width (in most regex implementations).

More information on this page

How to select records from last 24 hours using SQL?

FROM tableName 
WHERE datecolumn >= dateadd(hour,-24,getdate())

How to Convert string "07:35" (HH:MM) to TimeSpan

You can convert the time using the following code.

TimeSpan _time = TimeSpan.Parse("07:35");

But if you want to get the current time of the day you can use the following code:

TimeSpan _CurrentTime = DateTime.Now.TimeOfDay;

The result will be:


With a object cantain the Hours, Minutes, Seconds, Ticks and etc.

How to convert Nonetype to int or string?

That TypeError only appears when you try to pass int() None (which is the only NoneType value, as far as I know). I would say that your real goal should not be to convert NoneType to int or str, but to figure out where/why you're getting None instead of a number as expected, and either fix it or handle the None properly.

Creating a Facebook share button with customized url, title and image

This is the code as 2017:

<i class="fa fa-facebook-square"></i>
<a href="#" onclick="''+encodeURIComponent(location.href),'facebook-share-dialog','width=626,height=436');return false;">Share on Facebook</a>

Facebook now takes all data from OG metatags.

NOTE: This code assumes you have OG metatags on in site's code.


How to get single value from this multi-dimensional PHP array

Look at the keys and indentation in your print_r:

echo $myarray[0]['email'];

echo $myarray[0]['gender'];


How is Perl's @INC constructed? (aka What are all the ways of affecting where Perl modules are searched for?)

In addition to the locations listed above, the OS X version of Perl also has two more ways:

  1. The /Library/Perl/x.xx/AppendToPath file. Paths listed in this file are appended to @INC at runtime.

  2. The /Library/Perl/x.xx/PrependToPath file. Paths listed in this file are prepended to @INC at runtime.

How to use patterns in a case statement?

Brace expansion doesn't work, but *, ? and [] do. If you set shopt -s extglob then you can also use extended pattern matching:

  • ?() - zero or one occurrences of pattern
  • *() - zero or more occurrences of pattern
  • +() - one or more occurrences of pattern
  • @() - one occurrence of pattern
  • !() - anything except the pattern

Here's an example:

shopt -s extglob
for arg in apple be cd meet o mississippi
    # call functions based on arguments
    case "$arg" in
        a*             ) foo;;    # matches anything starting with "a"
        b?             ) bar;;    # matches any two-character string starting with "b"
        c[de]          ) baz;;    # matches "cd" or "ce"
        me?(e)t        ) qux;;    # matches "met" or "meet"
        @(a|e|i|o|u)   ) fuzz;;   # matches one vowel
        m+(iss)?(ippi) ) fizz;;   # matches "miss" or "mississippi" or others
        *              ) bazinga;; # catchall, matches anything not matched above

IF EXIST C:\directory\ goto a else goto b problems windows XP batch files

From the help (if /?):

The ELSE clause must occur on the same line as the command after the IF.  For

    IF EXIST filename. (
        del filename.
    ) ELSE (
        echo filename. missing.

The following would NOT work because the del command needs to be terminated
by a newline:

    IF EXIST filename. del filename. ELSE echo filename. missing

Nor would the following work, since the ELSE command must be on the same line
as the end of the IF command:

    IF EXIST filename. del filename.
    ELSE echo filename. missing

OpenJDK availability for Windows OS

In case you are still looking for a Windows build of OpenJDK, Azul Systems launched the Zulu product line last fall. The Zulu distribution of OpenJDK is built and tested on Windows and Linux. We posted the OpenJDK 8 version this week, though OpenJDK 7 and 6 are both available too. The following URL leads to you free downloads, the Zulu community forum, and other details: These are binary downloads, so you do not need to build OpenJDK from scratch to use them.

I can attest that building OpenJDK 6 for Windows was not a trivial exercise. Of the six different platforms we've built (OpenJDK6, OpenJDK7, and OpenJDK8, each for Windows and Linux) for x64 so far, the Windows OpenJDK6 build took by far the most effort to wring out items that didn't work on Windows, or would not pass the Technical Compatibility Kit test protocol for Java SE 6 "as is."

Disclaimer: I am the Product Manager for Zulu. You can review my Zulu release notices here: I hope this helps.

Embed Youtube video inside an Android app

How it looks:

enter image description here

Best solution to my case. I need video fit web view size. Use embed youtube link with your video id. Example:

WebView youtubeWebView; //todo find or bind web view
String myVideoYoutubeId = "-bvXmLR3Ozc";

outubeWebView.setWebViewClient(new WebViewClient() {
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                return false;

WebSettings webSettings = youtubeWebView.getSettings();

youtubeWebView.loadUrl("" + myVideoYoutubeId);

Web view xml code


Color picker utility (color pipette) in Ubuntu

I recommend GPick:

sudo apt-get install gpick

Applications -> Graphics -> GPick

It has many more features than gcolor2 but is still extremely simple to use: click on one of the hex swatches, move your mouse around the screen over the colours you want to pick, then press the Space bar to add to your swatch list.

If that doesn't work, another way is to click-and-drag from the centre of the hexagon and release your mouse over the pixel that you want to sample. Then immediately hit Space to copy that color into the next swatch in rotation.

It also has a traditional colour picker (like gcolor2) in the bottom right-hand corner of the window to allow you to pick individual colours with magnification.

Setting onClickListener for the Drawable right of an EditText

Please use below trick:

  • Create an image button with your icon and set its background color to be transparent.
  • Put the image button on the EditText
  • Implement the 'onclic'k listener of the button to execute your function

How to tell Maven to disregard SSL errors (and trusting all certs)?

Create a folder ${USER_HOME}/.mvn and put a file called maven.config in it.

The content should be:


Hope this helps.

Capturing multiple line output into a Bash variable

After trying most of the solutions here, the easiest thing I found was the obvious - using a temp file. I'm not sure what you want to do with your multiple line output, but you can then deal with it line by line using read. About the only thing you can't really do is easily stick it all in the same variable, but for most practical purposes this is way easier to deal with.

./ > /tmp/foo
while read line ; do 
    echo 'whatever you want to do with $line'
done < /tmp/foo

Quick hack to make it do the requested action:

./ > /tmp/foo
while read line ; do
done < /tmp/foo
echo -e $result

Note this adds an extra line. If you work on it you can code around it, I'm just too lazy.

EDIT: While this case works perfectly well, people reading this should be aware that you can easily squash your stdin inside the while loop, thus giving you a script that will run one line, clear stdin, and exit. Like ssh will do that I think? I just saw it recently, other code examples here:

One more time! This time with a different filehandle (stdin, stdout, stderr are 0-2, so we can use &3 or higher in bash).

while read line  <&3; do
done 3</tmp/foo
echo -e $result

you can also use mktemp, but this is just a quick code example. Usage for mktemp looks like:

filenamevar=`mktemp /tmp/tempXXXXXX`
./test > $filenamevar

Then use $filenamevar like you would the actual name of a file. Probably doesn't need to be explained here but someone complained in the comments.

Copy and paste content from one file to another file in vi

Use the variations of d like dd to cut.

To write a range of lines to another file you can use:

:<n>,<m> w filename

Where <n> and <m> are numbers (or symbols) that designate a range of lines.

For using the desktop clipboard, take a look at the +g commands.

How can I write maven build to add resources to classpath?

If you place anything in src/main/resources directory, then by default it will end up in your final *.jar. If you are referencing it from some other project and it cannot be found on a classpath, then you did one of those two mistakes:

  1. *.jar is not correctly loaded (maybe typo in the path?)
  2. you are not addressing the resource correctly, for instance: /src/main/resources/conf/ is seen on classpath as classpath:conf/

What is the <leader> in a .vimrc file?

Be aware that when you do press your <leader> key you have only 1000ms (by default) to enter the command following it.

This is exacerbated because there is no visual feedback (by default) that you have pressed your <leader> key and vim is awaiting the command; and so there is also no visual way to know when this time out has happened.

If you add set showcmd to your vimrc then you will see your <leader> key appear in the bottom right hand corner of vim (to the left of the cursor location) and perhaps more importantly you will see it disappear when the time out happens.

The length of the timeout can also be set in your vimrc, see :help timeoutlen for more information.

Sum values from an array of key-value pairs in JavaScript

You can use the native map method for Arrays. map Method (Array) (JavaScript)

var myData = new Array(['2013-01-22', 0], ['2013-01-29', 0], ['2013-02-05', 0],
             ['2013-02-12', 0], ['2013-02-19', 0], ['2013-02-26', 0], 
             ['2013-03-05', 0], ['2013-03-12', 0], ['2013-03-19', 0], 
             ['2013-03-26', 0], ['2013-04-02', 21], ['2013-04-09', 2]);
var a = 0; function(aa){ a += aa[1];  return a; });

a is your result

How to hide Bootstrap previous modal when you opening new one?

The best that I've been able to do is


This gets the modal holding the DOM object you triggered the event on (guessing you're clicking a button). Gets the closest parent '.modal' and toggles it. Obviously only works because it's inside the modal you clicked.

You can however do this:


This gets the modal that is displaying (since you can only have one open at a time), and triggers the 'toggle' This would not work without ":visible"

Changing git commit message after push (given that no one pulled from remote)

This works for me pretty fine,

git checkout origin/branchname

if you're already in branch then it's better to do pull or rebase

git pull


git -c core.quotepath=false fetch origin --progress --prune

Later you can simply use

git commit --amend -m "Your message here"

or if you like to open text-editor then use

git commit --amend

I will prefer using text-editor if you have many comments. You can set your preferred text-editor with command

git config --global core.editor your_preffered_editor_here

Anyway, when your are done changing the commit message, save it and exit

and then run

git push --force

And you're done

How to change a Git remote on Heroku

If you have multiple applications on heroku and want to add changes to a particular application, run the following command : heroku git:remote -a appname and then run the following. 1) git add . 2)git commit -m "changes" 3)git push heroku master

Intent from Fragment to Activity

 FragmentManager fragmentManager =  getFragmentManager();
 fragmentManager.beginTransaction().replace(, new MySchedule()).commit();

MySchedule is the name of my java class.

Tensorflow installation error: not a supported wheel on this platform

I faced the same issue and tried all the solutions that folks suggested here and other links (like

It was so frustrating because using print(wheel.pep425tags.get_supported()) I could see that my ubuntu supported ('cp37', 'cp37m', 'linux_x86_64') and that was exactly what I was trying to install (from

What at the end fixed it was to simply download the package first and then

pip install tensorflow-1.14.0-cp37-cp37m-linux_x86_64.whl

Deny access to one specific folder in .htaccess

Create site/includes/.htaccess file and add this line:

Deny from all

CodeIgniter - accessing $config variable in view

Also, the Common function config_item() works pretty much everywhere throughout the CodeIgniter instance. Controllers, models, views, libraries, helpers, hooks, whatever.

Resize height with Highcharts

I had a similar problem with height except my chart was inside a bootstrap modal popup, which I'm already controlling the size of with css. However, for some reason when the window was resized horizontally the height of the chart container would expand indefinitely. If you were to drag the window back and forth it would expand vertically indefinitely. I also don't like hard-coded height/width solutions.

So, if you're doing this in a modal, combine this solution with a window resize event.

// from link
$('#ChartModal').on('', function() {
    $('.chart-container').css('visibility', 'hidden');

$('#ChartModal').on('', function() {
    $('.chart-container').css('visibility', 'initial');
    ratio = $('.chart-container').width() / $('.chart-container').height();

Where "ratio" becomes a height/width aspect ratio, that will you resize when the bootstrap modal resizes. This measurement is only taken when he modal is opened. I'm storing ratio as a global but that's probably not best practice.

$(window).on('resize', function() {
    //chart-container is only visible when the modal is visible.
    if ( $('.chart-container').is(':visible') ) {
            ($('.chart-container').width() / ratio),
            doAnimation = true );

So with this, you can drag your screen to the side (resizing it) and your chart will maintain its aspect ratio.


enter image description here

vs smaller

enter image description here

(still fiddling around with vw units, so everything in the back is too small to read lol!)

How to keep environment variables when using sudo

For individual variables you want to make available on a one off basis you can make it part of the command.

sudo http_proxy=$http_proxy wget ""

How can I detect browser type using jQuery?

I have used this and it works for me.Also include jquery migrate plugin,and jquery file.

if ( $.browser.webkit ) {
alert( "This is WebKit!" );

Determine if 2 lists have the same elements, regardless of order?

This seems to work, though possibly cumbersome for large lists.

>>> A = [0, 1]
>>> B = [1, 0]
>>> C = [0, 2]
>>> not sum([not i in A for i in B])
>>> not sum([not i in A for i in C])

However, if each list must contain all the elements of other then the above code is problematic.

>>> A = [0, 1, 2]
>>> not sum([not i in A for i in B])

The problem arises when len(A) != len(B) and, in this example, len(A) > len(B). To avoid this, you can add one more statement.

>>> not sum([not i in A for i in B]) if len(A) == len(B) else False

One more thing, I benchmarked my solution with timeit.repeat, under the same conditions used by Aaron Hall in his post. As suspected, the results are disappointing. My method is the last one. set(x) == set(y) it is.

>>> def foocomprehend(): return not sum([not i in data for i in data2])
>>> min(timeit.repeat('fooset()', 'from __main__ import fooset, foocount, foocomprehend'))
>>> min(timeit.repeat('foosort()', 'from __main__ import fooset, foocount, foocomprehend'))
>>> min(timeit.repeat('foocomprehend()', 'from __main__ import fooset, foocount, foocomprehend'))


"are there any issue we should expect from only storing and retreiving a money amount in a DOUBLE column ?"

It sounds like no rounding errors can be produced in your scenario and if there were, they would be truncated by the conversion to BigDecimal.

So I would say no.

However, there is no guarantee that some change in the future will not introduce a problem.

ASP.NET IIS Web.config [Internal Server Error]

I had the same problem.


  1. Click the right button in your site folder in "iis"
  2. "Convert to Application".

Assign keyboard shortcut to run procedure

The problem that I had with the above is that I wanted to associate a short cut key with a macro in an xlam which has no visible interface. I found that the folllowing worked

To associate a short cut key with a macro

In Excel (not VBA) on the Developer Tab click Macros - no macros will be shown Type the name of the Sub The Options button should then be enabled Click it Ctrl will be the default Hold down Shift and press the letter you want eg Shift and A will associate Ctrl-Shift-A with the Sub

Not able to install Python packages [SSL: TLSV1_ALERT_PROTOCOL_VERSION]

The following solution worked for me:

brew install python2

It also upgraded pip to version 1.10.1

How to add external fonts to android application

One more point in addition to the above answers. When using a font inside a fragment, the typeface instantiation should be done in the onAttach method ( override ) as given below:

public void onAttach(Activity activity){
    Typeface tf = Typeface.createFromAsset(getApplicationContext().getAssets(),"fonts/fontname.ttf");

There is a short span of time before a fragment is attached to an activity. If CreateFromAsset method is called before attaching fragment to an activity an error occurs.

MySQL: Set user variable from result of query

Yes, but you need to move the variable assignment into the query:

SET @user := 123456;
SELECT @group := `group` FROM user WHERE user = @user;
SELECT * FROM user WHERE `group` = @group;

Test case:

CREATE TABLE user (`user` int, `group` int);
INSERT INTO user VALUES (123456, 5);
INSERT INTO user VALUES (111111, 5);


SET @user := 123456;
SELECT @group := `group` FROM user WHERE user = @user;
SELECT * FROM user WHERE `group` = @group;

| user   | group |
| 123456 |     5 |
| 111111 |     5 |
2 rows in set (0.00 sec)

Note that for SET, either = or := can be used as the assignment operator. However inside other statements, the assignment operator must be := and not = because = is treated as a comparison operator in non-SET statements.


Further to comments below, you may also do the following:

SET @user := 123456;
SELECT `group` FROM user LIMIT 1 INTO @group; 
SELECT * FROM user WHERE `group` = @group;

Case-insensitive search

I like @CHR15TO's answer, unlike other answers I've seen on other similar questions, that answer actually shows how to properly escape a user provided search string (rather than saying it would be necessary without showing how).

However, it's still quite clunky, and possibly relatively slower. So why not have a specific solution to what is likely a common requirement for coders? (And why not include it in the ES6 API BTW?)

My answer [] on a similar question enables the following:

var haystack = 'A. BAIL. Of. Hay.';
var needle = 'bail.';
var index = haystack.naturalIndexOf(needle);

Get max and min value from array in JavaScript

Instead of .each, another (perhaps more concise) approach to getting all those prices might be:

var prices = $(products).children("li").map(function() {
    return $(this).prop("data-price");

additionally you may want to consider filtering the array to get rid of empty or non-numeric array values in case they should exist:

prices = prices.filter(function(n){ return(!isNaN(parseFloat(n))) });

then use Sergey's solution above:

var max = Math.max.apply(Math,prices);
var min = Math.min.apply(Math,prices);

What does \d+ mean in regular expression terms?

\d means 'digit'. + means, '1 or more times'. So \d+ means one or more digit. It will match 12 and 1.

wait until all threads finish their work in java

The existing answers said could join() each thread.

But there are several ways to get the thread array / list:

  • Add the Thread into a list on creation.
  • Use ThreadGroup to manage the threads.

Following code will use the ThreadGruop approach. It create a group first, then when create each thread specify the group in constructor, later could get the thread array via ThreadGroup.enumerate()


import org.testng.Assert;
import org.testng.annotations.Test;

 * synchronized block - learn,
 * @author eric
 * @date Apr 20, 2015 1:37:11 PM
public class SyncBlockLearn {
    private static final int TD_COUNT = 5; // thread count
    private static final int ROUND_PER_THREAD = 100; // round for each thread,
    private static final long INC_DELAY = 10; // delay of each increase,

    // sync block test,
    public void syncBlockTest() throws InterruptedException {
        Counter ct = new Counter();
        ThreadGroup tg = new ThreadGroup("runner");

        for (int i = 0; i < TD_COUNT; i++) {
            new Thread(tg, ct, "t-" + i).start();

        Thread[] tArr = new Thread[TD_COUNT];
        tg.enumerate(tArr); // get threads,

        // wait all runner to finish,
        for (Thread t : tArr) {

        System.out.printf("\nfinal count: %d\n", ct.getCount());
        Assert.assertEquals(ct.getCount(), TD_COUNT * ROUND_PER_THREAD);

    static class Counter implements Runnable {
        private final Object lkOn = new Object(); // the object to lock on,
        private int count = 0;

        public void run() {
            System.out.printf("[%s] begin\n", Thread.currentThread().getName());

            for (int i = 0; i < ROUND_PER_THREAD; i++) {
                synchronized (lkOn) {
                    System.out.printf("[%s] [%d] inc to: %d\n", Thread.currentThread().getName(), i, ++count);
                try {
                    Thread.sleep(INC_DELAY); // wait a while,
                } catch (InterruptedException e) {

            System.out.printf("[%s] end\n", Thread.currentThread().getName());

        public int getCount() {
            return count;

The main thread will wait for all threads in the group to finish.

ASP.NET MVC ActionLink and post method

You can't use an ActionLink because that just renders an anchor <a> tag.
You can use a jQuery AJAX post.
Or just call the form's submit method with or without jQuery (which would be non-AJAX), perhaps in the onclick event of whatever control takes your fancy.

Jenkins pipeline how to change to another folder

You can use the dir step, example:

dir("folder") {
    sh "pwd"

The folder can be relative or absolute path.

How to convert image file data in a byte array to a Bitmap?

Just try this:

Bitmap bitmap = BitmapFactory.decodeFile("/path/images/image.jpg");
ByteArrayOutputStream blob = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /* Ignored for PNGs */, blob);
byte[] bitmapdata = blob.toByteArray();

If bitmapdata is the byte array then getting Bitmap is done like this:

Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapdata, 0, bitmapdata.length);

Returns the decoded Bitmap, or null if the image could not be decoded.

Scope 'session' is not active for the current thread; IllegalStateException: No thread-bound request found

If anyone else stuck on same point, following solved my problem.

In web.xml


In Session component

@Scope(value = "session",  proxyMode = ScopedProxyMode.TARGET_CLASS)

In pom.xml


How can I insert multiple rows into oracle with a sequence value?

This works:

insert into TABLE_NAME (COL1,COL2)
select my_seq.nextval, a

MySQL: how to get the difference between two timestamps in seconds


If you want an unsigned difference, add an ABS() around the expression.

Alternatively, you can use TIMEDIFF(ts1, ts2) and then convert the time result to seconds with TIME_TO_SEC().

What is the facade design pattern?

Its simply creating a wrapper to call multiple methods . You have an A class with method x() and y() and B class with method k() and z(). You want to call x, y, z at once , to do that using Facade pattern you just create a Facade class and create a method lets say xyz(). Instead of calling each method (x,y and z) individually you just call the wrapper method (xyz()) of the facade class which calls those methods .

Similar pattern is repository but it s mainly for the data access layer.

How do you calculate log base 2 in Java for integers?

This is the function that I use for this calculation:

public static int binlog( int bits ) // returns 0 for bits=0
    int log = 0;
    if( ( bits & 0xffff0000 ) != 0 ) { bits >>>= 16; log = 16; }
    if( bits >= 256 ) { bits >>>= 8; log += 8; }
    if( bits >= 16  ) { bits >>>= 4; log += 4; }
    if( bits >= 4   ) { bits >>>= 2; log += 2; }
    return log + ( bits >>> 1 );

It is slightly faster than Integer.numberOfLeadingZeros() (20-30%) and almost 10 times faster (jdk 1.6 x64) than a Math.log() based implementation like this one:

private static final double log2div = 1.000000000001 / Math.log( 2 );
public static int log2fp0( int bits )
    if( bits == 0 )
        return 0; // or throw exception
    return (int) ( Math.log( bits & 0xffffffffL ) * log2div );

Both functions return the same results for all possible input values.

Update: The Java 1.7 server JIT is able to replace a few static math functions with alternative implementations based on CPU intrinsics. One of those functions is Integer.numberOfLeadingZeros(). So with a 1.7 or newer server VM, a implementation like the one in the question is actually slightly faster than the binlog above. Unfortunatly the client JIT doesn't seem to have this optimization.

public static int log2nlz( int bits )
    if( bits == 0 )
        return 0; // or throw exception
    return 31 - Integer.numberOfLeadingZeros( bits );

This implementation also returns the same results for all 2^32 possible input values as the the other two implementations I posted above.

Here are the actual runtimes on my PC (Sandy Bridge i7):

JDK 1.7 32 Bits client VM:

binlog:         11.5s
log2nlz:        16.5s
log2fp:        118.1s
log(x)/log(2): 165.0s

JDK 1.7 x64 server VM:

binlog:          5.8s
log2nlz:         5.1s
log2fp:         89.5s
log(x)/log(2): 108.1s

This is the test code:

int sum = 0, x = 0;
long time = System.nanoTime();
do sum += log2nlz( x ); while( ++x != 0 );
time = System.nanoTime() - time;
System.out.println( "time=" + time / 1000000L / 1000.0 + "s -> " + sum );

How to use radio buttons in ReactJS?

import React, { Component } from "react";

class RadionButtons extends Component {
  constructor(props) {

    this.state = {
      // gender : "" , // use this one if you don't wanna any default value for gender
      gender: "male" // we are using this state to store the value of the radio button and also use to display the active radio button

    this.handleRadioChange = this.handleRadioChange.bind(this);  // we require access to the state of component so we have to bind our function 

  // this function is called whenever you change the radion button 
  handleRadioChange(event) {
      // set the new value of checked radion button to state using setState function which is async funtion

  render() {
    return (
        <div check>
            value="male" // this is te value which will be picked up after radio button change
            checked={this.state.gender === "male"} // when this is true it show the male radio button in checked 
            onChange={this.handleRadioChange} // whenever it changes from checked to uncheck or via-versa it goes to the handleRadioChange function
           style={{ marginLeft: "5px" }} // inline style in reactjs 
        <div check>
            checked={this.state.gender === "female"}
          <span style={{ marginLeft: "5px" }}>Female</span>
export default RadionButtons;

Sleep function in Windows, using C


#include <windows.h>

Sleep(sometime_in_millisecs); // Note uppercase S

And here's a small example that compiles with MinGW and does what it says on the tin:

#include <windows.h>
#include <stdio.h>

int main() {
    printf( "starting to sleep...\n" );
    Sleep(3000); // Sleep three seconds
    printf("sleep ended\n");

Android findViewById() in Custom View

View Custmv;

 private void initViews() {
        inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        Custmv = inflater.inflate(R.layout.id_number_edit_text_custom, this, true);
        editText = (EditText) findViewById(;
        loadButton = (ImageButton) findViewById(;

private void loadData(){
        loadButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                EditText firstName = (EditText) Custmv.getParent().findViewById(;
                firstName.setText("Some Text");

try like this.

Trigger function when date is selected with jQuery UI datepicker

Working demo :



    onSelect: function(dateText, inst) {
        var date = $(this).val();
        var time = $('#time').val();
        alert('on select triggered');
        $("#start").val(date + time.toString(' HH:mm').toString());


How to remove border from specific PrimeFaces p:panelGrid?

I am using Primefaces 6.0 and in order to remove borders from my panel grid i use this style class "ui-noborder" as follow:

<p:panelGrid columns="3" styleClass="ui-noborder">
   <!--panel grid contents -->

It uses a css file named "components" in primefaces lib

Run chrome in fullscreen mode on Windows

You can also add --disable-session-crashed-bubble to eliminate the errors that come up after a crash or improper shutdown.

Do C# Timers elapse on a separate thread?

If the elapsed event takes longer then the interval, it will create another thread to raise the elapsed event. But there is a workaround for this

static void timer_Elapsed(object sender, ElapsedEventArgs e)    

TimeSpan to DateTime conversion

If you only need to show time value in a datagrid or label similar, best way is convert directly time in datetime datatype.

SELECT CONVERT(datetime,myTimeField) as myTimeField FROM Table1

'list' object has no attribute 'shape'

firstly u have to import numpy library (refer code for making a numpy array) shape only gives the output only if the variable is attribute of numpy library .in other words it must be a np.array or any other data structure of numpy. Eg.

`>>> import numpy
>>> a=numpy.array([[1,1],[1,1]])
>>> a.shape
(2, 2)`

JavaScript: IIF like statement

I typed this in my URL bar:

javascript:{ var col = 'screwdriver'; var x = '<option value="' + col + '"' + ((col == 'screwdriver') ? ' selected' : '') + '>Very roomy</option>'; alert(x); }

A server is already running. Check …/tmp/pids/ Exiting - rails

It happens sometimes because you turn off the server by force, for example turning off the OS/machine manually so that the server does not have enough time to log to

One easy way is to manually go to tmp/pids/ (the directory that is shown in your console.) and remove file. Then, when you start the server again, rails server or rails s ,it creates a new and you can continue development.

GitHub "fatal: remote origin already exists"

First do a:

git remote rm origin


git remote add origin

and voila! Worked for me!

PHP Parse HTML code

Use PHP Document Object Model:

   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   $DOM = new DOMDocument;

   //get all H1
   $items = $DOM->getElementsByTagName('h1');

   //display all H1 text
   for ($i = 0; $i < $items->length; $i++)
        echo $items->item($i)->nodeValue . "<br/>";

This outputs as:


[EDIT]: After OP Clarification:

If you want the content like Lorem ipsum. etc, you can directly use this regex:

   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   echo preg_replace("#<h1.*?>.*?</h1>#", "", $str);

this outputs:

Lorem ipsum.The quick red fox...... jumps over the lazy brown FROG

Setting active profile and config location from command line in spring boot -Dspring.config.location=C:\Config

is not correct.

should be: --spring.config.location=C:\Config

getting only name of the class Class.getName()

The below both ways works fine.

System.out.println("The Class Name is: " + this.getClass().getName());
System.out.println("The simple Class Name is: " + this.getClass().getSimpleName());

Output as below:

The Class Name is: package.Student

The simple Class Name is: Student

Does C have a "foreach" loop construct?

There is no foreach in C.

You can use a for loop to loop through the data but the length needs to be know or the data needs to be terminated by a know value (eg. null).

char* nullTerm;
nullTerm = "Loop through my characters";

for(;nullTerm != NULL;nullTerm++)
    //nullTerm will now point to the next character.

gradlew: Permission Denied

on android folder cmd run

chmod +x gradlew

and run

./gradlew clean

and root project run

react-native run-android

How to check if NSString begins with a certain character

NSString *stringWithoutAsterisk(NSString *string) {
    NSRange asterisk = [string rangeOfString:@"*"];
    return asterisk.location == 0 ? [string substringFromIndex:1] : string;

Where does Android emulator store SQLite database?

according to Android docs, Monitor was deprecated in Android Studio 3.1 and removed from Android Studio 3.2. To access files, there is a tab in android studio called "Device File Explorer" bottom-right side of developing window which you can access your emulator file system. Just follow


good luck.

Android device File explorer

How to scroll table's "tbody" independent of "thead"?

try this.

    background-color: #aaa;

    background-color: #ddd;
    height: 100px;
    overflow-y: scroll;
    position: absolute;

    padding: 3px 10px;
    color: green;
    width: 100px;

How to receive JSON as an MVC 5 action method parameter

fwiw, this didn't work for me until I had this in the ajax call:

contentType: "application/json; charset=utf-8",

using Asp.Net MVC 4.

Automatically get loop index in foreach loop in Perl

Well, there is this way:

use List::Rubyish;

$list = List::Rubyish->new( [ qw<a b c> ] );
$list->each_index( sub { say "\$_=$_" } );

See List::Rubyish.