Programs & Examples On #Rmi

Remote Method Invocation (RMI) is Java's object-oriented remote procedure call (RPC) mechanism.

What is the difference between Java RMI and RPC?

Remote Procedure Call (RPC) is a inter process communication which allows calling a function in another process residing in local or remote machine.

Remote method invocation (RMI) is an API, which implements RPC in java with support of object oriented paradigms.

  1. You can think of invoking RPC is like calling a C procedure. RPC supports primitive data types where as RMI support method parameters/return types as java objects.

  2. RMI is easy to program unlike RPC. You can think your business logic in terms of objects instead of a sequence of primitive data types.

  3. RPC is language neutral unlike RMI, which is limited to java

  4. RMI is little bit slower to RPC

Have a look at this article for RPC implementation in C :connection timed out: connect?

The error message says it all: your connection timed out. This means your request did not get a response within some (default) timeframe. The reasons that no response was received is likely to be one of:

  • a) The IP/domain or port is incorrect
  • b) The IP/domain or port (i.e service) is down
  • c) The IP/domain is taking longer than your default timeout to respond
  • d) You have a firewall that is blocking requests or responses on whatever port you are using
  • e) You have a firewall that is blocking requests to that particular host
  • f) Your internet access is down

Note that firewalls and port or IP blocking may be in place by your ISP

java.rmi.ConnectException: Connection refused to host:;

Maybe your rmiregistry not be created before client trying connect to your server and it would lead to this exception.In Linux, you can use "netstat" to check your rmiregistry be bond on the right port you assigned in java code.

What port is used by Java RMI connection?

All the answers so far are incorrect. The Registry normally uses port 1099, but you can change it. But that's not the end of the story. Remote objects also use ports, and not necessarily 1099.

If you don't specify a port when exporting, RMI uses a random port. The solution is therefore to specify a port number when exporting. And this is a port that needs opening in the firewall, if any.

  • In the case where your remote object extends UnicastRemoteObject, have its constructor call super(port) with some non-zero port number.

  • In the case where it doesn't extend UnicastRemoteObject, provide a non-zero port number to UnicastRemoteObject.exportObject().

There are several wrinkles to this.

  • If you aren't using socket factories, and you provide a non-zero port number when exporting your first remote object, RMI will automatically share that port with subsequently exported remote objects without specified port numbers, or specifying zero. That first remote object includes a Registry created with LocateRegistry.createRegistry(). So if you create a Registry on port 1099, all other objects exported from that JVM can share port 1099.

  • If you are using socket factories, your RMIServerSocketFactory must have a sensible implementation of equals() for port sharing to work, i.e. one that doesn't just rely on object identity via == or Object.equals().

  • If either you don't provide a server socket factory, or you do provide one with a sensible equals() method, but not both, you can use the same non-zero explicit port number for all remote objects, e.g. createRegistry(1099) followed by any number of super(1099) or exportObject(..., 1099) calls.

Rmi connection refused with localhost

it seems that you should set your command as an String[],for example:

String[] command = new String[]{"rmiregistry","2020"};

it just like the style of main(String[] args).

What is wrong with my SQL here? #1089 - Incorrect prefix key

I also had this same problem.
Solution work for me:

  `sr_no` int(11) NOT NULL AUTO_INCREMENT,
  `username` VARCHAR(50) NOT NULL,
    `password` VARCHAR(50) NOT NULL,
    `dir` VARCHAR(100) NOT NULL,
  PRIMARY KEY (`sr_no`)

I paste this code in SQL and run, it works fine.

CSS Input Type Selectors - Possible to have an "or" or "not" syntax?

input[type='text'], input[type='password']
   // my css

That is the correct way to do it. Sadly CSS is not a programming language.

Get date from input form within PHP

Validate the INPUT.

$time = strtotime($_POST['dateFrom']);
if ($time) {
  $new_date = date('Y-m-d', $time);
  echo $new_date;
} else {
   echo 'Invalid Date: ' . $_POST['dateFrom'];
  // fix it.

Converting data frame column from character to numeric

If we need only one column to be numeric

yyz$b <- as.numeric(as.character(yyz$b))

But, if all the columns needs to changed to numeric, use lapply to loop over the columns and convert to numeric by first converting it to character class as the columns were factor.

yyz[] <- lapply(yyz, function(x) as.numeric(as.character(x)))

Both the columns in the OP's post are factor because of the string "n/a". This could be easily avoided while reading the file using na.strings = "n/a" in the read.table/read.csv or if we are using data.frame, we can have character columns with stringsAsFactors=FALSE (the default is stringsAsFactors=TRUE)

Regarding the usage of apply, it converts the dataset to matrix and matrix can hold only a single class. To check the class, we need

lapply(yyz, class)


sapply(yyz, class)

Or check


Best practice multi language website

A really simple option that works with any website where you can upload Javascript is

It lets you put all text for all languages onto one page and then hides the languages the user doesn't need to see. Works well.

How to customise file type to syntax associations in Sublime Text?

for ST3

$language = "language u wish"

if exists,

go to ~/.config/sublime-text-3/Packages/User/$language.sublime-settings


create ~/.config/sublime-text-3/Packages/User/$language.sublime-settings

and set

{ "extensions": [ "yourextension" ] }

This way allows you to enable syntax for composite extensions (e.g. sql.mustache, js.php, etc ... )

JavaScript DOM: Find Element Index In Container

    const nodes = el.parentNode.childNodes );
    const index = nodes.indexOf(el);
    console.log('index = ', index);

Get the last element of a std::string

*(myString.end() - 1) maybe? That's not exactly elegant either.

A python-esque would be asking too much of an already-bloated class.

Uncaught TypeError: Cannot set property 'value' of null

You don't have an element with the id u.That's why the error occurs. Note that the global variable document.getElementById("u").value means you are trying to get the value of input element with name u and its not defined in your code.

ASP.NET MVC: No parameterless constructor defined for this object

I got this error. I was using interfaces in my constructor and my dependency resolver wasn't able to resolve, when i registered it then the error went away.

Sorting by date & time in descending order?

I used a simpler solution found partly here:
How to sort details with Date and time in sql server ?
I used this query to get my results:

SELECT TOP (5) * FROM My_Table_Name WHERE id=WhateverValueINeed ORDER BY DateTimeColumnName DESC

This is more straight forward and worked for me.

Notice: the column of the Date has the "datetime" type

How to convert list to string

L = ['L','O','L']
makeitastring = ''.join(map(str, L))

How to connect Bitbucket to Jenkins properly

In order to build your repo after new commits, use Bitbucket Plugin.

There is just one thing to notice: When creating a POST Hook (notice that it is POST hook, not Jenkins hook), the URL works when it has a "/" in the end. Like:

URL: JENKINS_URL/bitbucket-hook/
e.g. someAddress:8080/bitbucket-hook/

Do not forget to check "Build when a change is pushed to Bitbucket" in your job configuration.

Selecting/excluding sets of columns in pandas

You don't really need to convert that into a set:

cols = [col for col in df.columns if col not in ['B', 'D']]
df2 = df[cols]

Java: Convert a String (representing an IP) to InetAddress

Simply call InetAddress.getByName(String host) passing in your textual IP address.

From the javadoc: The host name can either be a machine name, such as "", or a textual representation of its IP address.

InetAddress javadoc

Multiple Java versions running concurrently under Windows

I use a simple script when starting jmeter with my own java versin

setlocal set JAVA_HOME="c:\java8" set PATH=%JAVA_HOME%\bin;%PATH%; java -version

to have a java "portable" you can use this method here:

How to install Java SDK on CentOS?

If you want the Oracle JDK and are willing not to use yum/rpm, see this answer here:

Downloading Java JDK on Linux via wget is shown license page instead

As per that post, you can automate the download of the tarball using curl and specifying a cookie header.

Then you can put the tarball contents in the right place and add java to your PATH, for example:

curl -v -j -k -L -H "Cookie: oraclelicense=accept-securebackup-cookie" > jdk.tar.gz

tar xzvf jdk.tar.gz
sudo mkdir /usr/local/java
sudo mv jdk1.8.0_45 /usr/local/java/
sudo ln -s /usr/local/java/jdk1.8.0_45 /usr/local/java/jdk

sudo vi /etc/profile.d/
export PATH="$PATH:/usr/local/java/jdk/bin"
export JAVA_HOME=/usr/local/java/jdk

source /etc/profile.d/

Convert String[] to comma separated string in java

This would be an optimized way of doing it

StringBuilder sb = new StringBuilder();
for (String n : arr) { 
return sb.toString();

How do I reference the input of an HTML <textarea> control in codebehind?

You are not using a .NET control for your text area. Either add runat="server" to the HTML TextArea control or use a .NET control:

Try this:

<asp:TextBox id="TextArea1" TextMode="multiline" Columns="50" Rows="5" runat="server" />

Then reference it in your codebehind:

message.Body = TextArea1.Text;

Jquery- Get the value of first td in table


parent gives you the <td> around the link,

siblings gives all the <td> tags in that <tr>,

:first gives the first matched element in the set.

text() gives the contents of the tag.

./configure : /bin/sh^M : bad interpreter

If you're on OS X, you can change line endings in XCode by opening the file and selecting the

View -> Text -> Line Endings -> Unix

menu item, then Save. This is for XCode 3.x. Probably something similar in XCode 4.

How to create a file in Ruby

data = 'data you want inside the file'.

You can use File.write('name of file here', data)

Copy rows from one Datatable to another DataTable?

As a result of the other posts, this is the shortest I could get:

DataTable destTable = sourceTable.Clone();
sourceTable.AsEnumerable().Where(row => /* condition */ ).ToList().ForEach(row => destTable.ImportRow(row));

Does C# support multiple inheritance?

You can't inherit multiple classes at a time. But there is an options to do that by the help of interface. See below code

interface IA
    void PrintIA();

class  A:IA
    public void PrintIA()
        Console.WriteLine("PrintA method in Base Class A");

interface IB
    void PrintIB();

class B : IB
    public void PrintIB()
        Console.WriteLine("PrintB method in Base Class B");

public class AB: IA, IB
    A a = new A();
    B b = new B();

    public void PrintIA()

    public void PrintIB()

you can call them as below

AB ab = new AB();

Cookies vs. sessions

Session and Cookie are not a same.

A session is used to store the information from the web pages. Normally web pages don’t have any memories to store these information. But using we can save the necessary information.

But Cookie is used to identifying the users. Using cookie we can store the data’s. It is a small part of data which will store in user web browser. So whenever user browse next time browser send back the cookie data information to server for getting the previous activities.

Credits : Session and Cookie

How do I count columns of a table

I have a more general answer; but I believe it is useful for counting the columns for all tables in a DB:

SELECT table_name, count(*)
FROM information_schema.columns
GROUP BY table_name;

Getting number of days in a month

You want DateTime.DaysInMonth:

int days = DateTime.DaysInMonth(year, month);

Obviously it varies by year, as sometimes February has 28 days and sometimes 29. You could always pick a particular year (leap or not) if you want to "fix" it to one value or other.

Content type 'application/x-www-form-urlencoded;charset=UTF-8' not supported for @RequestBody MultiValueMap

The problem is that when we use application/x-www-form-urlencoded, Spring doesn't understand it as a RequestBody. So, if we want to use this we must remove the @RequestBody annotation.

Then try the following:

@RequestMapping(value = "/{email}/authenticate", method = RequestMethod.POST,
        consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE, 
public @ResponseBody  Representation authenticate(@PathVariable("email") String anEmailAddress, MultiValueMap paramMap) throws Exception {
   if(paramMap == null && paramMap.get("password") == null) {
        throw new IllegalArgumentException("Password not provided");
    return null;

Note that removed the annotation @RequestBody

answer: Http Post request with content type application/x-www-form-urlencoded not working in Spring

Change date format in a Java string

Say you want to change 2019-12-20 10:50 AM GMT+6:00 to 2019-12-20 10:50 AM first of all you have to understand the date format first one date format is yyyy-MM-dd hh:mm a zzz and second one date format will be yyyy-MM-dd hh:mm a

just return a string from this function like.

public String convertToOnlyDate(String currentDate) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm a ");
    Date date;
    String dateString = "";
    try {
        date = dateFormat.parse(currentDate);

        dateString = dateFormat.format(date);
    } catch (ParseException e) {
    return dateString;

This function will return your desire answer. If you want to customize more just add or remove component from the date format.

How do I properly set the Datetimeindex for a Pandas datetime object in a dataframe?

You are not creating datetime index properly,

format = '%Y-%m-%d %H:%M:%S'
df['Datetime'] = pd.to_datetime(df['date'] + ' ' + df['time'], format=format)
df = df.set_index(pd.DatetimeIndex(df['Datetime']))

SqlServer: Login failed for user

I got the same error message when trying to connect to my SQL DB in Azure (using sql-cli). The simple solution was to escape the password with single quotes like this:

mssql -s -u user@server -p 'your_password' -d your_db -e

How to clear basic authentication details in chrome

Things changed a lot since the answer was posted. Now you will see a small key symbol on the right hand side of the URL bar.
Click the symbol and it will take you directly to the saved password dialog where you can remove the password.

Successfully tested in Chrome 49

Center HTML Input Text Field Placeholder

If you want to change only the placeholder style

::-webkit-input-placeholder {
   text-align: center;

:-moz-placeholder { /* Firefox 18- */
   text-align: center;  

::-moz-placeholder {  /* Firefox 19+ */
   text-align: center;  

:-ms-input-placeholder {  
   text-align: center; 

jQuery Scroll to bottom of page/iframe


I use this code to scroll the chat when new messages arrive.

What is a Maven artifact?

An artifact is a file, usually a JAR, that gets deployed to a Maven repository.

A Maven build produces one or more artifacts, such as a compiled JAR and a "sources" JAR.

Each artifact has a group ID (usually a reversed domain name, like, an artifact ID (just a name), and a version string. The three together uniquely identify the artifact.

A project's dependencies are specified as artifacts.

How to add buttons dynamically to my form?

use button array like will create 3 dynamic buttons bcoz h variable has value of 3

private void button1_Click(object sender, EventArgs e)
int h =3;

Button[] buttonArray = new Button[8];

for (int i = 0; i <= h-1; i++)
   buttonArray[i] = new Button();
   buttonArray[i].Size = new Size(20, 43);
   buttonArray[i].Name= ""+i+"";
   buttonArray[i].Click += button_Click;//function
   buttonArray[i].Location = new Point(40, 20 + (i * 20));

}  }

How to delete a specific file from folder using

string sourceDir = @"c:\current";
string backupDir = @"c:\archives\2008";

    string[] picList = Directory.GetFiles(sourceDir, "*.jpg");
    string[] txtList = Directory.GetFiles(sourceDir, "*.txt");

    // Copy picture files. 
    foreach (string f in picList)
        // Remove path from the file name. 
        string fName = f.Substring(sourceDir.Length + 1);

        // Use the Path.Combine method to safely append the file name to the path. 
        // Will overwrite if the destination file already exists.
        File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName), true);

    // Copy text files. 
    foreach (string f in txtList)

        // Remove path from the file name. 
        string fName = f.Substring(sourceDir.Length + 1);

            // Will not overwrite if the destination file already exists.
            File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName));

        // Catch exception if the file was already copied. 
        catch (IOException copyError)

    // Delete source files that were copied. 
    foreach (string f in txtList)
    foreach (string f in picList)

catch (DirectoryNotFoundException dirNotFound)

How to force the browser to reload cached CSS and JavaScript files

Don’t use foo.css?version=1!

Browsers aren't supposed to cache URLs with GET variables. According to, though Internet Explorer and Firefox ignore this, Opera and Safari don't! Instead, use foo.v1234.css, and use rewrite rules to strip out the version number.

How to input a string from user into environment variable from batch file

You can use set with the /p argument:

SET /P variable=[promptString]

The /P switch allows you to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. The promptString can be empty.

So, simply use something like

set /p Input=Enter some text: 

Later you can use that variable as argument to a command:

myCommand %Input%

Be careful though, that if your input might contain spaces it's probably a good idea to quote it:

myCommand "%Input%"

Accessing post variables using Java Servlets

Your HttpServletRequest object has a getParameter(String paramName) method that can be used to get parameter values.

How to pass html string to webview on android

Passing null would be better. The full codes is like:

WebView wv = (WebView)this.findViewById(;
wv.loadDataWithBaseURL(null, "<html>...</html>", "text/html", "utf-8", null);

numpy array TypeError: only integer scalar arrays can be converted to a scalar index

Short answer:

[a[:,:j] for j in i]

What you are trying to do is not a vectorizable operation. Wikipedia defines vectorization as a batch operation on a single array, instead of on individual scalars:

In computer science, array programming languages (also known as vector or multidimensional languages) generalize operations on scalars to apply transparently to vectors, matrices, and higher-dimensional arrays.


... an operation that operates on entire arrays can be called a vectorized operation...

In terms of CPU-level optimization, the definition of vectorization is:

"Vectorization" (simplified) is the process of rewriting a loop so that instead of processing a single element of an array N times, it processes (say) 4 elements of the array simultaneously N/4 times.

The problem with your case is that the result of each individual operation has a different shape: (3, 1), (3, 2) and (3, 3). They can not form the output of a single vectorized operation, because the output has to be one contiguous array. Of course, it can contain (3, 1), (3, 2) and (3, 3) arrays inside of it (as views), but that's what your original array a already does.

What you're really looking for is just a single expression that computes all of them:

[a[:,:j] for j in i]

... but it's not vectorized in a sense of performance optimization. Under the hood it's plain old for loop that computes each item one by one.

PHP passing $_GET in linux command prompt

-- Option 1: php-cgi --

Use 'php-cgi' in place of 'php' to run your script. This is the simplest way as you won't need to specially modify your php code to work with it:

php-cgi -f /my/script/file.php a=1 b=2 c=3

-- Option 2: if you have a web server --

If the php file is on a web server you can use 'wget' on the command line:

wget 'http://localhost/my/script/file.php?a=1&b=2&c=3'


wget -q -O - "http://localhost/my/script/file.php?a=1&b=2&c=3"

-- Accessing the variables in php --

In both option 1 & 2 you access these parameters like this:

$a = $_GET["a"];
$b = $_GET["b"];
$c = $_GET["c"];

Jquery onclick on div



<script type="text/javascript">

    $("#div1").on('click', function(){



<div id="div1">div!</div>

How to detect Adblock on my website?

This one works good

if there's an adBlocker it will alert you


function checkAdBlocker() {
    try {
            new Request("", {
                method: 'HEAD',
                mode: 'no-cors'
            })).catch(error => {
    } catch (e) {
        // Request failed, likely due to ad blocker

function showNotification() {
    alert("Please disable adBlocker")

Automatically set appsettings.json for dev and release environments in core?

You may use conditional compilation:

public Startup(IHostingEnvironment env)
    var builder = new ConfigurationBuilder()
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddJsonFile($"appsettings.flag_a.json", optional: true)
    .AddJsonFile($"appsettings.no_flag_a.json", optional: true)
    this.configuration = builder.Build();

xlsxwriter: is there a way to open an existing worksheet in my workbook?

You can use the workbook.get_worksheet_by_name() feature:

According to the feature has been added on May 13, 2016.

"Release 0.8.7 - May 13 2016

-Fix for issue when inserting read-only images on Windows. Issue #352.

-Added get_worksheet_by_name() method to allow the retrieval of a worksheet from a workbook via its name.

-Fixed issue where internal file creation and modification dates were in the local timezone instead of UTC."

MySQL ORDER BY multiple column ASC and DESC

@DRapp is a genius. I never understood how he coded his SQL,so I tried coding it in my own understanding.

        JOIN users
        ON scores.user_id =
        ORDER BY scores.point DESC
        ) userscores
      ORDER BY
        point DESC,
      ) f
    GROUP BY f.username
    ORDER BY point DESC

It yields the same result by using GROUP BY instead of the user @variables.

ASP.NET custom error page - Server.GetLastError() is null

One important consideration that I think everybody is missing here is a load-balancing (web farm) scenario. Since the server that's executing global.asax may be different than the server that's about the execute the custom error page, stashing the exception object in Application is not reliable.

I'm still looking for a reliable solution to this problem in a web farm configuration, and/or a good explanation from MS as to why you just can't pick up the exception with Server.GetLastError on the custom error page like you can in global.asax Application_Error.

P.S. It's unsafe to store data in the Application collection without first locking it and then unlocking it.

Why does using an Underscore character in a LIKE filter give me all the results?

Modify your WHERE condition like this:

WHERE mycolumn LIKE '%\_%' ESCAPE '\'

This is one of the ways in which Oracle supports escape characters. Here you define the escape character with the escape keyword. For details see this link on Oracle Docs.

The '_' and '%' are wildcards in a LIKE operated statement in SQL.

The _ character looks for a presence of (any) one single character. If you search by columnName LIKE '_abc', it will give you result with rows having 'aabc', 'xabc', '1abc', '#abc' but NOT 'abc', 'abcc', 'xabcd' and so on.

The '%' character is used for matching 0 or more number of characters. That means, if you search by columnName LIKE '%abc', it will give you result with having 'abc', 'aabc', 'xyzabc' and so on, but no 'xyzabcd', 'xabcdd' and any other string that does not end with 'abc'.

In your case you have searched by '%_%'. This will give all the rows with that column having one or more characters, that means any characters, as its value. This is why you are getting all the rows even though there is no _ in your column values.

COPY with docker but with exclusion

FOR A ONE LINER SOLUTION, type the following in Command prompt or Terminal at project root.

echo node_modules > .dockerignore

This creates the extension-less . prefixed file without any issue. Replace node_modules with the folder you want to exclude.

Maven "build path specifies execution environment J2SE-1.5", even though I changed it to 1.7

When creating a maven project in eclipse, the build path is set to JDK 1.5 regardless of settings, which is probably a bug in new project or m2e.

HTTP Status 500 - Servlet.init() for servlet Dispatcher threw exception

<project xmlns="" xmlns:xsi=""

            <name>PrimeFaces Maven Repository</name>








Regex: ignore case sensitivity

Just for the sake of completeness I wanted to add the solution for regular expressions in C++ with Unicode:

std::tr1::wregex pattern(szPattern, std::tr1::regex_constants::icase);

if (std::tr1::regex_match(szString, pattern))

Get connection string from App.config

string sTemp = System.Configuration.ConfigurationManager.ConnectionStrings["myDB In app.config"].ConnectionString;

How to split a file into equal parts, without breaking individual lines?

A simple solution for a simple question:

split -n l/5 your_file.txt

no need for scripting here.

From the man file, CHUNKS may be:

l/N     split into N files without splitting lines


Not all unix dist include this flag. For example, it will not work in OSX. To use it, you can consider replacing the Mac OS X utilities with GNU core utilities.

HTTPS using Jersey Client

HTTPS using Jersey client has two different version if you are using java 6 ,7 and 8 then

SSLContext sc = SSLContext.getInstance("SSL");

If using java 8 then

SSLContext sc = SSLContext.getInstance("TLSv1");
System.setProperty("https.protocols", "TLSv1");

Please find working code


<project xmlns="" xmlns:xsi=""
            <name> Repository for Maven</name>




        <!-- Jersey -->



        <!-- Spring 3 dependencies -->



        <!-- Jersey + Spring -->



package com.example.client;

import org.glassfish.jersey.client.authentication.HttpAuthenticationFeature;
import org.springframework.http.HttpStatus;

public class JerseyClientGet {
    public static void main(String[] args) {
        String username = "username";
            String password = "p@ssword";
        String input = "{\"userId\":\"12345\",\"name \":\"Viquar\",\"surname\":\"Khan\",\"Email\":\"[email protected]\"}";
        try {
        //SSLContext sc = SSLContext.getInstance("SSL");//Java 6
        SSLContext sc = SSLContext.getInstance("TLSv1");//Java 8
        System.setProperty("https.protocols", "TLSv1");//Java 8

        TrustManager[] trustAllCerts = { new InsecureTrustManager() };
        sc.init(null, trustAllCerts, new;
        HostnameVerifier allHostsValid = new InsecureHostnameVerifier();

        Client client = ClientBuilder.newBuilder().sslContext(sc).hostnameVerifier(allHostsValid).build();

        HttpAuthenticationFeature feature = HttpAuthenticationFeature.universalBuilder()
                    .credentialsForBasic(username, password).credentials(username, password).build();

                    //PUT request, if need uncomment it 
                    //final Response response = client
                    //.request().put(Entity.entity(input, MediaType.APPLICATION_JSON), Response.class);
            //GET Request
            final Response response = client

            if (response.getStatus() != HttpStatus.OK.value()) { throw new RuntimeException("Failed : HTTP error code : "
                    + response.getStatus()); }
            String output = response.readEntity(String.class);
            System.out.println("Output from Server .... \n");
        } catch (Exception e) {


package com.example.client;


public class InsecureHostnameVerifier implements HostnameVerifier {
    public boolean verify(String hostname, SSLSession session) {
        return true;

Helper class

package com.example.client;


public class InsecureTrustManager implements X509TrustManager {
     * {@inheritDoc}
    public void checkClientTrusted(final X509Certificate[] chain, final String authType) throws CertificateException {
        // Everyone is trusted!

     * {@inheritDoc}
    public void checkServerTrusted(final X509Certificate[] chain, final String authType) throws CertificateException {
        // Everyone is trusted!

     * {@inheritDoc}
    public X509Certificate[] getAcceptedIssuers() {
        return new X509Certificate[0];

Once you start running application will get Certificate error ,download certificate from browser and add into


Add into cacerts , you will get details in following links.

Few useful link to understand error

I have tested following code for get and post method with SSL and basic Authentication here you can skip SSL Certificate , you can directly copy three class and add jar into java project and run.

import org.glassfish.jersey.client.authentication.HttpAuthenticationFeature;
import org.glassfish.jersey.filter.LoggingFilter;

public class RestClientTest {
     * @param args
    public static void main(String[] args) {
        try {
        } catch (KeyManagementException e1) {
            // TODO Auto-generated catch block
        } catch (NoSuchAlgorithmException e1) {
            // TODO Auto-generated catch block
        } catch (IOException e1) {
            // TODO Auto-generated catch block

    private static WebTarget    target      = null;
    private static String       userName    = "username";
    private static String       passWord    = "password";

    public static void sslRestClientGETReport() throws KeyManagementException, IOException, NoSuchAlgorithmException {
        SSLContext sc = SSLContext.getInstance("SSL");
        TrustManager[] trustAllCerts = { new InsecureTrustManager() };
        sc.init(null, trustAllCerts, new;
        HostnameVerifier allHostsValid = new InsecureHostnameVerifier();
        Client c = ClientBuilder.newBuilder().sslContext(sc).hostnameVerifier(allHostsValid).build();
        String baseUrl = "https://localhost:7002/VaquarKhanWeb/employee/api/v1/informations/report";
        c.register(HttpAuthenticationFeature.basic(userName, passWord));
        target =;
        target.register(new LoggingFilter());
        String responseMsg = target.request().get(String.class);


    public static void sslRestClientGET() throws KeyManagementException, IOException, NoSuchAlgorithmException {
        //Query param Search={JSON}
        SSLContext sc = SSLContext.getInstance("SSL");
        TrustManager[] trustAllCerts = { new InsecureTrustManager() };
        sc.init(null, trustAllCerts, new;
        HostnameVerifier allHostsValid = new InsecureHostnameVerifier();
        Client c = ClientBuilder.newBuilder().sslContext(sc).hostnameVerifier(allHostsValid).build();
        String baseUrl = "https://localhost:7002/VaquarKhanWeb";

        c.register(HttpAuthenticationFeature.basic(userName, passWord));
        target =;
        target = target.path("employee/api/v1/informations/employee/data").queryParam("search","%7B\"name\":\"vaquar\",\"surname\":\"khan\",\"age\":\"30\",\"type\":\"admin\""%7D");

        target.register(new LoggingFilter());
        String responseMsg = target.request().get(String.class);

    //TOD need to fix
    public static void sslRestClientPost() throws KeyManagementException, IOException, NoSuchAlgorithmException {
        Employee employee = new Employee("vaquar", "khan", "30", "E");
        SSLContext sc = SSLContext.getInstance("SSL");
        TrustManager[] trustAllCerts = { new InsecureTrustManager() };
        sc.init(null, trustAllCerts, new;
        HostnameVerifier allHostsValid = new InsecureHostnameVerifier();
        Client c = ClientBuilder.newBuilder().sslContext(sc).hostnameVerifier(allHostsValid).build();
        String baseUrl = "https://localhost:7002/VaquarKhanWeb/employee/api/v1/informations/employee";
        c.register(HttpAuthenticationFeature.basic(userName, passWord));
        target =;
        target.register(new LoggingFilter());
        Response response = target.request().put(Entity.json(employee));
        String output = response.readEntity(String.class);





Getting the name of the currently executing method

I don't know what is the intention behind getting the currently executed method's name, but if that's just for debugging purpose, then logging frameworks like "logback" can help here. For example, in logback, all you need to do is to use the pattern "%M" in your logging configuration. However, this should be used with caution as this may degrade performance.

Splitting a Java String by the pipe symbol using split("|")

You can also use .split("[|]").

(I used this instead of .split("\\|"), which didn't work for me.)

Extract public/private key from PKCS12 file for later use in SSH-PK-Authentication

OpenSSH cannot use PKCS#12 files out of the box. As others suggested, you must extract the private key in PEM format which gets you from the land of OpenSSL to OpenSSH. Other solutions mentioned here don’t work for me. I use OS X 10.9 Mavericks (10.9.3 at the moment) with “prepackaged” utilities (OpenSSL 0.9.8y, OpenSSH 6.2p2).

First, extract a private key in PEM format which will be used directly by OpenSSH:

openssl pkcs12 -in filename.p12 -clcerts -nodes -nocerts | openssl rsa > ~/.ssh/id_rsa

I strongly suggest to encrypt the private key with password:

openssl pkcs12 -in filename.p12 -clcerts -nodes -nocerts | openssl rsa -passout 'pass:Passw0rd!' > ~/.ssh/id_rsa

Obviously, writing a plain-text password on command-line is not safe either, so you should delete the last command from history or just make sure it doesn’t get there. Different shells have different ways. You can prefix your command with space to prevent it from being saved to history in Bash and many other shells. Here is also how to delete the command from history in Bash:

history -d $(history | tail -n 2 | awk 'NR == 1 { print $1 }')

Alternatively, you can use different way to pass a private key password to OpenSSL - consult OpenSSL documentation for pass phrase arguments.

Then, create an OpenSSH public key which can be added to authorized_keys file:

ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/

Submitting a multidimensional array via POST with php

I made a function which handles arrays as well as single GET or POST values

function subVal($varName, $default=NULL,$isArray=FALSE ){ // $isArray toggles between (multi)array or single mode

    $retVal = "";
    $retArray = array();

    if($isArray) {
        if(isset($_POST[$varName])) {
            foreach ( $_POST[$varName] as $var ) {  // multidimensional POST array elements

    elseif (isset($_POST[$varName]) )  {  // simple POST array element
        $retVal = $_POST[$varName];

    else {
        if (isset($_GET[$varName]) ) {
            $retVal = $_GET[$varName];    // simple GET array element
        else {
            $retVal = $default;

    return $retVal;



$curr_topdiameter = subVal("topdiameter","",TRUE)[3];
$user_name = subVal("user_name","");

Read Session Id using Javascript

you can receive the session id by issuing the following regular expression on document.cookie:


in my example the cookie name to store session id is PHPSESSID (php server), just replace the PHPSESSID with the cookie name that holds the session id. (configurable by the web server)

Android RecyclerView addition & removal of items

Possibly a duplicate answer but quite useful for me. You can implement the method given below in RecyclerView.Adapter<RecyclerView.ViewHolder> and can use this method as per your requirements, I hope it will work for you

public void removeItem(@NonNull Object object) {

one line if statement in php

Something like this?

($var > 2 ? echo "greater" : echo "smaller")

Using number_format method in Laravel

Here's another way of doing it, add in app\Providers\AppServiceProvider.php

use Illuminate\Support\Str;


public function boot()
    // add Str::currency macro
    Str::macro('currency', function ($price)
        return number_format($price, 2, '.', '\'');

Then use Str::currency() in the blade templates or directly in the Expense model.

@foreach ($Expenses as $Expense)
        <td>{{{ $Expense->type }}}</td>
        <td>{{{ $Expense->narration }}}</td>
        <td>{{{ Str::currency($Expense->price) }}}</td>
        <td>{{{ $Expense->quantity }}}</td>
        <td>{{{ Str::currency($Expense->amount) }}}</td>                                                            

Create a day-of-week column in a Pandas dataframe using Python

In version 0.18.1 is added dt.weekday_name:

print df
    my_dates  myvals
0 2015-01-01       1
1 2015-01-02       2
2 2015-01-03       3

print df.dtypes
my_dates    datetime64[ns]
myvals               int64
dtype: object

df['day_of_week'] = df['my_dates'].dt.weekday_name
print df
    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

Another solution with assign:

print df.assign(day_of_week = df['my_dates'].dt.weekday_name)
    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

Excel VBA date formats

To ensure that a cell will return a date value and not just a string that looks like a date, first you must set the NumberFormat property to a Date format, then put a real date into the cell's content.

Sub test_date_or_String()
 Set c = ActiveCell
 c.NumberFormat = "@"
 c.Value = CDate("03/04/2014")
   Debug.Print c.Value & " is a " & TypeName(c.Value) 'C is a String
 c.NumberFormat = "m/d/yyyy"
   Debug.Print c.Value & " is a " & TypeName(c.Value) 'C is still a String
 c.Value = CDate("03/04/2014")
   Debug.Print c.Value & " is a " & TypeName(c.Value) 'C is a date    
End Sub

Visual Studio SignTool.exe Not Found

Here is a solution for Visual Studio 2017. The installer looks a littlebit different from the VS 2015 version and the name of the installation packages are different.

How to send FormData objects with Ajax-requests in jQuery?


function submitForm() {
    var data1 = new FormData($('input[name^="file"]'));
    $.each($('input[name^="file"]')[0].files, function(i, file) {
        data1.append(i, file);

        url: "<?php echo base_url() ?>employee/dashboard2/test2",
        type: "POST",
        data: data1,
        enctype: 'multipart/form-data',
        processData: false, // tell jQuery not to process the data
        contentType: false // tell jQuery not to set contentType
    }).done(function(data) {
        console.log("PHP Output:");
    return false;


public function upload_file() {
    foreach($_FILES as $key) {
        $name = time().$key['name'];
        $path = 'upload/'.$name;
        @move_uploaded_file($key['tmp_name'], $path);

Find duplicate characters in a String and count the number of occurances using Java

public static void findDuplicate(String letter)

    for(int i=0; i<letter.length();i++)
        for( int j=i+1; j<letter.length();j++)


The OUTPUT is : A

How do I print the percent sign(%) in c

Try printing out this way


A non well formed numeric value encountered

This is an old question, but there is another subtle way this message can happen. It's explained pretty well here, in the docs.

Imagine this scenerio:

try {
  // code that triggers a pdo exception
} catch (Exception $e) {
  throw new MyCustomExceptionHandler($e);

And MyCustomExceptionHandler is defined roughly like:

class MyCustomExceptionHandler extends Exception {
  public function __construct($e) {
    parent::__construct($e->getMessage(), $e->getCode());

This will actually trigger a new exception in the custom exception handler because the Exception class is expecting a number for the second parameter in its constructor, but PDOException might have dynamically changed the return type of $e->getCode() to a string.

A workaround for this would be to define you custom exception handler like:

class MyCustomExceptionHandler extends Exception {
  public function __construct($e) {
    $this->code = $e->getCode();

Rendering HTML inside textarea

I have the same problem but in reverse, and the following solution. I want to put html from a div in a textarea (so I can edit some reactions on my website; I want to have the textarea in the same location.)

To put the content of this div in a textarea I use:

var content = $('#msg500').text();_x000D_
$('#msg500').wrapInner('<textarea>' + content + '</textarea>');
<script src=""></script>_x000D_
<div id="msg500">here some <strong>html</strong> <i>tags</i>.</div>

OS X Sprite Kit Game Optimal Default Window Size

You should target the smallest, not the largest, supported pixel resolution by the devices your app can run on.

Say if there's an actual Mac computer that can run OS X 10.9 and has a native screen resolution of only 1280x720 then that's the resolution you should focus on. Any higher and your game won't correctly run on this device and you could as well remove that device from your supported devices list.

You can rely on upscaling to match larger screen sizes, but you can't rely on downscaling to preserve possibly important image details such as text or smaller game objects.

The next most important step is to pick a fitting aspect ratio, be it 4:3 or 16:9 or 16:10, that ideally is the native aspect ratio on most of the supported devices. Make sure your game only scales to fit on devices with a different aspect ratio.

You could scale to fill but then you must ensure that on all devices the cropped areas will not negatively impact gameplay or the use of the app in general (ie text or buttons outside the visible screen area). This will be harder to test as you'd actually have to have one of those devices or create a custom build that crops the view accordingly.

Alternatively you can design multiple versions of your game for specific and very common screen resolutions to provide the best game experience from 13" through 27" displays. Optimized designs for iMac (desktop) and a Macbook (notebook) devices make the most sense, it'll be harder to justify making optimized versions for 13" and 15" plus 21" and 27" screens.

But of course this depends a lot on the game. For example a tile-based world game could simply provide a larger viewing area onto the world on larger screen resolutions rather than scaling the view up. Provided that this does not alter gameplay, like giving the player an unfair advantage (specifically in multiplayer).

You should provide @2x images for the Retina Macbook Pro and future Retina Macs.

Apache redirect to another port

You should leave out the domain in ProxyPass and ProxyPassReverse and leave it as /. Additionally, you need to leave the / at the end of example/ to where it is redirecting. Also, I had some trouble with vs. - only the www worked until I made the ServerName, and the ServerAlias Give the following a go.

<VirtualHost *:80> 
  ProxyPreserveHost On
  ProxyRequests Off
  ProxyPass / http://localhost:8080/example/
  ProxyPassReverse / http://localhost:8080/example/

After you make these changes, add the needed modules and restart apache

sudo a2enmod proxy && sudo a2enmod proxy_http && sudo service apache2 restart

2D array values C++

Just want to point out you do not need to specify all dimensions of the array.

The leftmost dimension can be 'guessed' by the compiler.

#include <stdio.h>
int main(void) {
  int arr[][5] = {{1,2,3,4,5}, {5,6,7,8,9}, {6,5,4,3,2}};
  printf("sizeof arr is %d bytes\n", (int)sizeof arr);
  printf("number of elements: %d\n", (int)(sizeof arr/sizeof arr[0]));
  return 0;

How to resolve this JNI error when trying to run LWJGL "Hello World"?

A CLASSPATH entry is either a directory at the head of a package hierarchy of .class files, or a .jar file. If you're expecting ./lib to include all the .jar files in that directory, it won't. You have to name them explicitly.


Starting in SQL Server 2017 the STRING_AGG function is available which simplifies the logic considerably:

select FieldA, string_agg(FieldB, '') as data
from yourtable
group by FieldA

See SQL Fiddle with Demo

In SQL Server you can use FOR XML PATH to get the result:

select distinct t1.FieldA,
  STUFF((SELECT distinct '' + t2.FieldB
         from yourtable t2
         where t1.FieldA = t2.FieldA
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,0,'') data
from yourtable t1;

See SQL Fiddle with Demo

How can I get a specific number child using CSS?

For modern browsers, use td:nth-child(2) for the second td, and td:nth-child(3) for the third. Remember that these retrieve the second and third td for every row.

If you need compatibility with IE older than version 9, use sibling combinators or JavaScript as suggested by Tim. Also see my answer to this related question for an explanation and illustration of his method.

Equal sized table cells to fill the entire width of the containing table

You don't even have to set a specific width for the cells, table-layout: fixed suffices to spread the cells evenly.

ul {_x000D_
    width: 100%;_x000D_
    display: table;_x000D_
    table-layout: fixed;_x000D_
    border-collapse: collapse;_x000D_
li {_x000D_
    display: table-cell;_x000D_
    text-align: center;_x000D_
    border: 1px solid hotpink;_x000D_
    vertical-align: middle;_x000D_
    word-wrap: break-word;_x000D_

Note that for table-layout to work the table styled element must have a width set (100% in my example).

Difference between Activity and FragmentActivity

A FragmentActivity is a subclass of Activity that was built for the Android Support Package.

The FragmentActivity class adds a couple new methods to ensure compatibility with older versions of Android, but other than that, there really isn't much of a difference between the two. Just make sure you change all calls to getLoaderManager() and getFragmentManager() to getSupportLoaderManager() and getSupportFragmentManager() respectively.

Add CSS to iFrame

Based on solution You've already found How to apply CSS to iframe?:

var cssLink = document.createElement("link") 
cssLink.href = "file://path/to/style.css"; 
cssLink .rel = "stylesheet"; 
cssLink .type = "text/css"; 

or more jqueryish (from Append a stylesheet to an iframe with jQuery):

var $head = $("iframe").contents().find("head");                
    { rel: "stylesheet", href: "file://path/to/style.css", type: "text/css" }));

as for security issues: Disabling same-origin policy in Safari

Django - after login, redirect user to his custom page -->

If you're using Django's built-in LoginView, it takes next as context, which is "The URL to redirect to after successful login. This may contain a query string, too." (see docs)

Also from the docs:

"If login is successful, the view redirects to the URL specified in next. If next isn’t provided, it redirects to settings.LOGIN_REDIRECT_URL (which defaults to /accounts/profile/)."

Example code:

from django.urls import path
from django.contrib.auth import views as auth_views

from account.forms import LoginForm # optional form to pass to view

urlpatterns = [

    # --------------- login url/view -------------------
    path('account/login/', auth_views.LoginView.as_view(

            # option 1: provide full path
            'next': '/account/my_custom_url/', 

            # option 2: just provide the name of the url
            # 'next': 'custom_url_name',  
    ), name='login'),




<form method="post" action="{% url 'login' %}">


  {# option 1 #}
  <input type="hidden" name="next" value="{{ next }}">

  {# option 2 #}
  {# <input type="hidden" name="next" value="{% url next %}"> #}


Error: [ng:areq] from angular controller

I have made a stupid mistake and wasted lot of time so adding this answer over here so that it helps someone

I was incorrectly adding the $scope variable(dependency)(was adding it without single quotes)

for example what i was doing was something like this


where the desired syntax is like this


PHP file_get_contents() and setting request headers

You can use this variable to retrieve response headers after file_get_contents() function.




array(9) {
  string(15) "HTTP/1.1 200 OK"
  string(35) "Date: Sat, 12 Apr 2008 17:30:38 GMT"
  string(29) "Server: Apache/2.2.3 (CentOS)"
  string(44) "Last-Modified: Tue, 15 Nov 2005 13:24:10 GMT"
  string(27) "ETag: "280100-1b6-80bfd280""
  string(20) "Accept-Ranges: bytes"
  string(19) "Content-Length: 438"
  string(17) "Connection: close"
  string(38) "Content-Type: text/html; charset=UTF-8"

.NET code to send ZPL to Zebra printers

I've managed a project that does this with sockets for years. Zebra's typically use port 6101. I'll look through the code and post what I can.

public void SendData(string zpl)
    NetworkStream ns = null;
    Socket socket = null;

        if (printerIP == null)
            /* IP is a string property for the printer's IP address. */
            /* 6101 is the common port of all our Zebra printers. */
            printerIP = new IPEndPoint(IPAddress.Parse(IP), 6101);  

        socket = new Socket(AddressFamily.InterNetwork,

        ns = new NetworkStream(socket);

        byte[] toSend = Encoding.ASCII.GetBytes(zpl);
        ns.Write(toSend, 0, toSend.Length);
        if (ns != null)

        if (socket != null && socket.Connected)

Get Context in a Service

Service extends ContextWrapper which extends Context. Hence the Service is a Context. Use 'this' keyword in the service.

How to initialize an array in angular2 and typescript

hi @JackSlayer94 please find the below example to understand how to make an array of size 5.

class Hero {_x000D_
    name: string;_x000D_
    constructor(text: string) {_x000D_ = text;_x000D_
    display() {_x000D_
        return "Hello, " +;_x000D_
let heros:Hero[] = new Array(5);_x000D_
for (let i = 0; i < 5; i++){_x000D_
    heros[i] = new Hero("Name: " + i);_x000D_
for (let i = 0; i < 5; i++){_x000D_

How can I get my webapp's base URL in ASP.NET MVC?

Assuming you have a Request object available, you can use:

string.Format("{0}://{1}{2}", Request.Url.Scheme, Request.Url.Authority, Url.Content("~"));

If it's not available, you can get to it via the context:

var request = HttpContext.Current.Request

Getting value from JQUERY datepicker

I needed to do this for a sales report that allows the user to choose a date range. The solution is similar to another answer, but I wanted to provide my example just to show you the practical real world use that I applied this to:

var reportHeader = `Product Sales History Report for ${$('#FromDate').val()} to ${$('#ToDate').val()}.` ;

Pygame mouse clicking detection

The MOUSEBUTTONDOWN event occurs once when you click the mouse button and the MOUSEBUTTONUP event occurs once when the mouse button is released. The pygame.event.Event() object has two attributes that provide information about the mouse event. pos is a tuple that stores the position that was clicked. button stores the button that was clicked. Each mouse button is associated a value. For instance the value of the attributes is 1, 2, 3, 4, 5 for the left mouse button, middle mouse button, right mouse button, mouse wheel up respectively mouse wheel down. When multiple keys are pressed, multiple mouse button events occur. Further explanations can be found in the documentation of the module pygame.event.

Use the rect attribute of the pygame.sprite.Sprite object and the collidepoint method to see if the Sprite was clicked. Pass the list of events to the update method of the pygame.sprite.Group so that you can process the events in the Sprite class:

class SpriteObject(pygame.sprite.Sprite):
    # [...]

    def update(self, event_list):

        for event in event_list:
            if event.type == pygame.MOUSEBUTTONDOWN:
                if self.rect.collidepoint(event.pos):
                    # [...]

my_sprite = SpriteObject()
group = pygame.sprite.Group(my_sprite)

# [...]

run = True
while run:
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            run = False 


    # [...]

Minimal example:

import pygame

class SpriteObject(pygame.sprite.Sprite):
    def __init__(self, x, y, color):
        self.original_image = pygame.Surface((50, 50), pygame.SRCALPHA), color, (25, 25), 25)
        self.click_image = pygame.Surface((50, 50), pygame.SRCALPHA), color, (25, 25), 25), (255, 255, 255), (25, 25), 25, 4)
        self.image = self.original_image 
        self.rect = self.image.get_rect(center = (x, y))
        self.clicked = False

    def update(self, event_list):
        for event in event_list:
            if event.type == pygame.MOUSEBUTTONDOWN:
                if self.rect.collidepoint(event.pos):
                    self.clicked = not self.clicked

        self.image = self.click_image if self.clicked else self.original_image

window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

sprite_object = SpriteObject(*window.get_rect().center, (128, 128, 0))
group = pygame.sprite.Group([
    SpriteObject(window.get_width() // 3, window.get_height() // 3, (128, 0, 0)),
    SpriteObject(window.get_width() * 2 // 3, window.get_height() // 3, (0, 128, 0)),
    SpriteObject(window.get_width() // 3, window.get_height() * 2 // 3, (0, 0, 128)),
    SpriteObject(window.get_width() * 2// 3, window.get_height() * 2 // 3, (128, 128, 0)),

run = True
while run:
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            run = False 




See further Creating multiple sprites with different update()'s from the same sprite class in Pygame

The current position of the mouse can be determined via pygame.mouse.get_pos(). The return value is a tuple that represents the x and y coordinates of the mouse cursor. pygame.mouse.get_pressed() returns a list of Boolean values ??that represent the state (True or False) of all mouse buttons. The state of a button is True as long as a button is held down. When multiple buttons are pressed, multiple items in the list are True. The 1st, 2nd and 3rd elements in the list represent the left, middle and right mouse buttons.

Detect evaluate the mouse states in the Update method of the pygame.sprite.Sprite object:

class SpriteObject(pygame.sprite.Sprite):
    # [...]

    def update(self, event_list):

        mouse_pos = pygame.mouse.get_pos()
        mouse_buttons = pygame.mouse.get_pressed()

        if  self.rect.collidepoint(mouse_pos) and any(mouse_buttons):
            # [...]

my_sprite = SpriteObject()
group = pygame.sprite.Group(my_sprite)

# [...]

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False


    # [...]

Minimal example:

import pygame

class SpriteObject(pygame.sprite.Sprite):
    def __init__(self, x, y, color):
        self.original_image = pygame.Surface((50, 50), pygame.SRCALPHA), color, (25, 25), 25)
        self.hover_image = pygame.Surface((50, 50), pygame.SRCALPHA), color, (25, 25), 25), (255, 255, 255), (25, 25), 25, 4)
        self.image = self.original_image 
        self.rect = self.image.get_rect(center = (x, y))
        self.hover = False

    def update(self):
        mouse_pos = pygame.mouse.get_pos()
        mouse_buttons = pygame.mouse.get_pressed()

        #self.hover = self.rect.collidepoint(mouse_pos)
        self.hover = self.rect.collidepoint(mouse_pos) and any(mouse_buttons)

        self.image = self.hover_image if self.hover else self.original_image

window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

sprite_object = SpriteObject(*window.get_rect().center, (128, 128, 0))
group = pygame.sprite.Group([
    SpriteObject(window.get_width() // 3, window.get_height() // 3, (128, 0, 0)),
    SpriteObject(window.get_width() * 2 // 3, window.get_height() // 3, (0, 128, 0)),
    SpriteObject(window.get_width() // 3, window.get_height() * 2 // 3, (0, 0, 128)),
    SpriteObject(window.get_width() * 2// 3, window.get_height() * 2 // 3, (128, 128, 0)),

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False 




How to get String Array from arrays.xml file

You can't initialize your testArray field this way, because the application resources still aren't ready.

Just change the code to:


import android.os.Bundle;
import android.widget.ArrayAdapter;

public class Episode7 extends ListActivity {
    String[] mTestArray;

    /** Called when the activity is first created. */
    protected void onCreate(Bundle savedInstanceState) {

        // Create an ArrayAdapter that will contain all list items
        ArrayAdapter<String> adapter;

        mTestArray = getResources().getStringArray(R.array.testArray);    

        /* Assign the name array to that adapter and 
        also choose a simple layout for the list items */ 
        adapter = new ArrayAdapter<String>(

        // Assign the adapter to this ListActivity

dyld: Library not loaded: @rpath/libswiftCore.dylib

I solved by deleting the derived data and this time it worked correctly. Tried with Xcode 7.3.1GM

.NET data structures: ArrayList, List, HashTable, Dictionary, SortedList, SortedDictionary -- Speed, memory, and when to use each?

.NET data structures:

More to conversation about why ArrayList and List are actually different


As one user states, Arrays are the "old school" collection (yes, arrays are considered a collection though not part of System.Collections). But, what is "old school" about arrays in comparison to other collections, i.e the ones you have listed in your title (here, ArrayList and List(Of T))? Let's start with the basics by looking at Arrays.

To start, Arrays in Microsoft .NET are, "mechanisms that allow you to treat several [logically-related] items as a single collection," (see linked article). What does that mean? Arrays store individual members (elements) sequentially, one after the other in memory with a starting address. By using the array, we can easily access the sequentially stored elements beginning at that address.

Beyond that and contrary to programming 101 common conceptions, Arrays really can be quite complex:

Arrays can be single dimension, multidimensional, or jadded (jagged arrays are worth reading about). Arrays themselves are not dynamic: once initialized, an array of n size reserves enough space to hold n number of objects. The number of elements in the array cannot grow or shrink. Dim _array As Int32() = New Int32(100) reserves enough space on the memory block for the array to contain 100 Int32 primitive type objects (in this case, the array is initialized to contain 0s). The address of this block is returned to _array.

According to the article, Common Language Specification (CLS) requires that all arrays be zero-based. Arrays in .NET support non-zero-based arrays; however, this is less common. As a result of the "common-ness" of zero-based arrays, Microsoft has spent a lot of time optimizing their performance; therefore, single dimension, zero-based (SZs) arrays are "special" - and really the best implementation of an array (as opposed to multidimensional, etc.) - because SZs have specific intermediary language instructions for manipulating them.

Arrays are always passed by reference (as a memory address) - an important piece of the Array puzzle to know. While they do bounds checking (will throw an error), bounds checking can also be disabled on arrays.

Again, the biggest hindrance to arrays is that they are not re-sizable. They have a "fixed" capacity. Introducing ArrayList and List(Of T) to our history:

ArrayList - non-generic list

The ArrayList (along with List(Of T) - though there are some critical differences, here, explained later) - is perhaps best thought of as the next addition to collections (in the broad sense). ArrayList inherit from the IList (a descendant of 'ICollection') interface. ArrayLists, themselves, are bulkier - requiring more overhead - than Lists.

IList does enable the implementation to treat ArrayLists as fixed-sized lists (like Arrays); however, beyond the additional functionallity added by ArrayLists, there are no real advantages to using ArrayLists that are fixed size as ArrayLists (over Arrays) in this case are markedly slower.

From my reading, ArrayLists cannot be jagged: "Using multidimensional arrays as elements... is not supported". Again, another nail in the coffin of ArrayLists. ArrayLists are also not "typed" - meaning that, underneath everything, an ArrayList is simply a dynamic Array of Objects: Object[]. This requires a lot of boxing (implicit) and unboxing (explicit) when implementing ArrayLists, again adding to their overhead.

Unsubstantiated thought: I think I remember either reading or having heard from one of my professors that ArrayLists are sort of the bastard conceptual child of the attempt to move from Arrays to List-type Collections, i.e. while once having been a great improvement to Arrays, they are no longer the best option as further development has been done with respect to collections

List(Of T): What ArrayList became (and hoped to be)

The difference in memory usage is significant enough to where a List(Of Int32) consumed 56% less memory than an ArrayList containing the same primitive type (8 MB vs. 19 MB in the above gentleman's linked demonstration: again, linked here) - though this is a result compounded by the 64-bit machine. This difference really demonstrates two things: first (1), a boxed Int32-type "object" (ArrayList) is much bigger than a pure Int32 primitive type (List); second (2), the difference is exponential as a result of the inner-workings of a 64-bit machine.

So, what's the difference and what is a List(Of T)? MSDN defines a List(Of T) as, "... a strongly typed list of objects that can be accessed by index." The importance here is the "strongly typed" bit: a List(Of T) 'recognizes' types and stores the objects as their type. So, an Int32 is stored as an Int32 and not an Object type. This eliminates the issues caused by boxing and unboxing.

MSDN specifies this difference only comes into play when storing primitive types and not reference types. Too, the difference really occurs on a large scale: over 500 elements. What's more interesting is that the MSDN documentation reads, "It is to your advantage to use the type-specific implementation of the List(Of T) class instead of using the ArrayList class...."

Essentially, List(Of T) is ArrayList, but better. It is the "generic equivalent" of ArrayList. Like ArrayList, it is not guaranteed to be sorted until sorted (go figure). List(Of T) also has some added functionality.

Filtering Sharepoint Lists on a "Now" or "Today"

In the View, modify the current view or create a new view and make a filter change, select the radio button "Show items only when the following is true", in the below columns type "Created" and in the next dropdown select "is less than" and fill the next column [Today]-7.

The keyword [Today] denotes the current day for the calculation and this view will show as per your requirement

jQuery selector for inputs with square brackets in the name attribute

Just separate it with different quotes:

<input name="myName[1][data]" value="myValue">


var value = $('input[name="myName[1][data]"]').val();

Does this app use the Advertising Identifier (IDFA)? - AdMob 6.8.0

BTW, Yandex Metrica also uses IDFA.


They say on their GitHub page that

"Starting from version 1.6.0 Yandex AppMetrica became also a tracking instrument and uses Apple idfa to attribute installs. Because of that during submitting your application to the AppStore you will be prompted with three checkboxes to state your intentions for idfa usage. As Yandex AppMetrica uses idfa for attributing app installations you need to select Attribute this app installation to a previously served advertisement."

So, I will try to select this checkbox and send my app without actually no any ads in it.

View more than one project/solution in Visual Studio

This is the way Visual Studio is designed: One solution, one Visual Studio (VS) instance.

Besides switching between solutions in one VS instance, you can also open another VS instance and open your other solution with that one. Next to solutions there are as you said "projects". You can have multiple projects within one solution and therefore view many projects at the same time.

How to check a Long for null in java

If it is Long object then You can use longValue == null or you can use Objects.isNull(longValue) method in Java 8 .

Please check Objects for more info.

Replace forward slash "/ " character in JavaScript string?

Area.replace(new RegExp(/\//g), '-') replaces multiple forward slashes (/) with -

Root user/sudo equivalent in Cygwin?

What I usually do is have a registry "Open Here" helper in order to open a cygwin shell with administrative privileges quite easy from anywhere in my computer.

Be aware you have to have the cygwin "chere" package installed, use "chere -i -m" from an elevated cygwin shell first.

Assuming your cygwin installation is in C:\cygwin...

Here's the registry code:

Windows Registry Editor Version 5.00


@="Open Cygwin Here as Root"

@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"


@="Open Cygwin Here as Root"

@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"


@="Open Cygwin Here as Root"

@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"

Hope this helps. Let me know if it works for you. Thanks.

PS: You can grab this code, copy and paste it and save it in a name.reg file to run it... or you can manually add the values.

Fastest way to count exact number of rows in a very large table?

If you are using Oracle, how about this (assuming the table stats are updated):

select <TABLE_NAME>, num_rows, last_analyzed from user_tables

last_analyzed will show the time when stats were last gathered.

Bootstrap visible and hidden classes not working properly

If you give display table property in css some div bootstrap hidden class will not effect on that div

Get Character value from KeyCode in JavaScript... then trim

You can also use the read-only property key. It also respects special keys like shift etc. and is supported by IE9.

When a non-printable or special character is pressed, the value will be on of the defined key values like 'Shift' or 'Multiply'.

  • Keyboard     event.key
  • X             -> 'x'
  • Shift+X -> 'X'
  • F5            -> 'F5'

Cannot execute RUN mkdir in a Dockerfile

When creating subdirectories hanging off from a non-existing parent directory(s) you must pass the -p flag to mkdir ... Please update your Dockerfile with

RUN mkdir -p ... 

I tested this and it's correct.

Tesseract running error

I'm using Visual Studio 2017 Community Edition.
I solved this problem by making a directory called tessdata in the Debug directory of my project. Then I put the eng.traineddata file into said directory.

How to query GROUP BY Month in a Year

You can use:

    select FK_Items,Sum(PoiQuantity) Quantity  from PurchaseOrderItems POI
    left join PurchaseOrder PO ON po.ID_PurchaseOrder=poi.FK_PurchaseOrder
    group by FK_Items,DATEPART(MONTH, TransDate)

VS 2012: Scroll Solution Explorer to current file

If you have ReSharper installed clicking Shift+Alt+L will move focus to the current file in Solution Explorer.

Active Item Tracking will also need to be enabled as described in the accepted answer

Tools->Options->Projects and Solutions->Track Active Item in Solution Explorer

How to display Wordpress search results?

I am using searchform.php and search.php files as already mentioned, but here I provide the actual code.

Creating a Search Page codex page helps here and #Creating_a_Search_Page_Template shows the search query.

In my case I pass the $search_query arguments to the WP_Query Class (which can determine if is search query!). I then run The Loop to display the post information I want to, which in my case is the the_permalink and the_title.

Search box form:

<form class="search" method="get" action="<?php echo home_url(); ?>" role="search">
  <input type="search" class="search-field" placeholder="<?php echo esc_attr_x( 'Search …', 'placeholder' ) ?>" value="<?php echo get_search_query() ?>" name="s" title="<?php echo esc_attr_x( 'Search for:', 'label' ) ?>" />
  <button type="submit" role="button" class="btn btn-default right"/><span class="glyphicon glyphicon-search white"></span></button>

search.php template file:

    global $query_string;
    $query_args = explode("&", $query_string);
    $search_query = array();

    foreach($query_args as $key => $string) {
      $query_split = explode("=", $string);
      $search_query[$query_split[0]] = urldecode($query_split[1]);
    } // foreach

    $the_query = new WP_Query($search_query);
    if ( $the_query->have_posts() ) : 
    <!-- the loop -->

    <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
            <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
    <?php endwhile; ?>
    <!-- end of the loop -->

    <?php wp_reset_postdata(); ?>

<?php else : ?>
    <p><?php _e( 'Sorry, no posts matched your criteria.' ); ?></p>
<?php endif; ?>

How to set image button backgroundimage for different state?

Try this

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

How do I access store state in React Redux?

Import connect from react-redux and use it to connect the component with the state connect(mapStates,mapDispatch)(component)

import React from "react";
import { connect } from "react-redux";

const MyComponent = (props) => {
    return (

Finally you need to map the states to the props to access them with this.props

const mapStateToProps = state => {
  return {
    title: state.title
export default connect(mapStateToProps)(MyComponent);

Only the states that you map will be accessible via props

Check out this answer:

For further reading :

Mysql: Select rows from a table that are not in another

This worked for me in Oracle:

    FROM tbl1 a 
    FROM tbl2 b;

Compare two columns using pandas

You can use .equals for columns or entire dataframes.


If they're equal, that statement will return True, else False.

mappedBy reference an unknown target entity property

public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column(name = "USER_ID")
    Long userId;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "sender", cascade = CascadeType.ALL)
    List<Notification> sender;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "receiver", cascade = CascadeType.ALL)
    List<Notification> receiver;

public class Notification implements Serializable {

    private static final long serialVersionUID = 1L;


    @Column(name = "NOTIFICATION_ID")
    Long notificationId;

    @Column(name = "TEXT")
    String text;

    @Column(name = "ALERT_STATUS")
    AlertStatus alertStatus = AlertStatus.NEW;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "SENDER_ID")
    User sender;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "RECEIVER_ID")
    User receiver;

What I understood from the answer. mappedy="sender" value should be the same in the notification model. I will give you an example..

User model:

@OneToMany(fetch = FetchType.LAZY, mappedBy = "**sender**", cascade = CascadeType.ALL)
    List<Notification> sender;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "**receiver**", cascade = CascadeType.ALL)
    List<Notification> receiver;

Notification model:

@OneToMany(fetch = FetchType.LAZY, mappedBy = "sender", cascade = CascadeType.ALL)
    List<Notification> **sender**;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "receiver", cascade = CascadeType.ALL)
    List<Notification> **receiver**;

I gave bold font to user model and notification field. User model mappedBy="sender " should be equal to notification List sender; and mappedBy="receiver" should be equal to notification List receiver; If not, you will get error.

Java, Check if integer is multiple of a number

//More Efficiently
public class Multiples {
    public static void main(String[]args) {

        int j = 5;

        System.out.println(j % 4 == 0);


Load More Posts Ajax Button in WordPress

UPDATE 24.04.2016.

I've created tutorial on my page about implementing this on Twenty Sixteen theme, so feel free to check it out :)


I've tested this on Twenty Fifteen and it's working, so it should be working for you.

In index.php (assuming that you want to show the posts on the main page, but this should work even if you put it in a page template) I put:

    <div id="ajax-posts" class="row">
            $postsPerPage = 3;
            $args = array(
                    'post_type' => 'post',
                    'posts_per_page' => $postsPerPage,
                    'cat' => 8

            $loop = new WP_Query($args);

            while ($loop->have_posts()) : $loop->the_post();

         <div class="small-12 large-4 columns">
                <h1><?php the_title(); ?></h1>
                <p><?php the_content(); ?></p>

    <div id="more_posts">Load More</div>

This will output 3 posts from category 8 (I had posts in that category, so I used it, you can use whatever you want to). You can even query the category you're in with

$cat_id = get_query_var('cat');

This will give you the category id to use in your query. You could put this in your loader (load more div), and pull with jQuery like

<div id="more_posts" data-category="<?php echo $cat_id; ?>">>Load More</div>

And pull the category with

var cat = $('#more_posts').data('category');

But for now, you can leave this out.

Next in functions.php I added

wp_localize_script( 'twentyfifteen-script', 'ajax_posts', array(
    'ajaxurl' => admin_url( 'admin-ajax.php' ),
    'noposts' => __('No older posts found', 'twentyfifteen'),

Right after the existing wp_localize_script. This will load WordPress own admin-ajax.php so that we can use it when we call it in our ajax call.

At the end of the functions.php file I added the function that will load your posts:

function more_post_ajax(){

    $ppp = (isset($_POST["ppp"])) ? $_POST["ppp"] : 3;
    $page = (isset($_POST['pageNumber'])) ? $_POST['pageNumber'] : 0;

    header("Content-Type: text/html");

    $args = array(
        'suppress_filters' => true,
        'post_type' => 'post',
        'posts_per_page' => $ppp,
        'cat' => 8,
        'paged'    => $page,

    $loop = new WP_Query($args);

    $out = '';

    if ($loop -> have_posts()) :  while ($loop -> have_posts()) : $loop -> the_post();
        $out .= '<div class="small-12 large-4 columns">


add_action('wp_ajax_nopriv_more_post_ajax', 'more_post_ajax');
add_action('wp_ajax_more_post_ajax', 'more_post_ajax');

Here I've added paged key in the array, so that the loop can keep track on what page you are when you load your posts.

If you've added your category in the loader, you'd add:

$cat = (isset($_POST['cat'])) ? $_POST['cat'] : '';

And instead of 8, you'd put $cat. This will be in the $_POST array, and you'll be able to use it in ajax.

Last part is the ajax itself. In functions.js I put inside the $(document).ready(); enviroment

var ppp = 3; // Post per page
var cat = 8;
var pageNumber = 1;

function load_posts(){
    var str = '&cat=' + cat + '&pageNumber=' + pageNumber + '&ppp=' + ppp + '&action=more_post_ajax';
        type: "POST",
        dataType: "html",
        url: ajax_posts.ajaxurl,
        data: str,
        success: function(data){
            var $data = $(data);
            } else{
        error : function(jqXHR, textStatus, errorThrown) {
            $loader.html(jqXHR + " :: " + textStatus + " :: " + errorThrown);

    return false;

$("#more_posts").on("click",function(){ // When btn is pressed.
    $("#more_posts").attr("disabled",true); // Disable the button, temp.

Saved it, tested it, and it works :)

Images as proof (don't mind the shoddy styling, it was done quickly). Also post content is gibberish xD

enter image description here

enter image description here

enter image description here


For 'infinite load' instead on click event on the button (just make it invisible, with visibility: hidden;) you can try with

$(window).on('scroll', function () {
    if ($(window).scrollTop() + $(window).height()  >= $(document).height() - 100) {

This should run the load_posts() function when you're 100px from the bottom of the page. In the case of the tutorial on my site you can add a check to see if the posts are loading (to prevent firing of the ajax twice), and you can fire it when the scroll reaches the top of the footer

$(window).on('scroll', function(){
    if($('body').scrollTop()+$(window).height() > $('footer').offset().top){
        if(!($loader.hasClass('post_loading_loader') || $loader.hasClass('post_no_more_posts'))){

Now the only drawback in these cases is that you could never scroll to the value of $(document).height() - 100 or $('footer').offset().top for some reason. If that should happen, just increase the number where the scroll goes to.

You can easily check it by putting console.logs in your code and see in the inspector what they throw out

$(window).on('scroll', function () {
    console.log($(window).scrollTop() + $(window).height());
    console.log($(document).height() - 100);
    if ($(window).scrollTop() + $(window).height()  >= $(document).height() - 100) {

And just adjust accordingly ;)

Hope this helps :) If you have any questions just ask.

Find duplicate records in a table using SQL Server

with x as   (select  *,rn = row_number()
            over(PARTITION BY OrderNo,item  order by OrderNo)
            from    #temp1)

select * from x
where rn > 1

you can remove duplicates by replacing select statement by

delete x where rn > 1

How to determine the current language of a wordpress page when using polylang?

I use something like this:


$lang = get_bloginfo("language"); 

if ($lang == 'fr-FR') : ?>


<?php endif; ?>

What is the first character in the sort order used by Windows Explorer?

I had the same problem. I wanted to 'bury' a folder at the bottom of the sort instead of bringing it to the top with the '!' character. Windows recognizes most special characters as just that, 'special', and therefore they ALL are sorted at the top.

However, if you think outside of the English characters, you will find a lot of luck. I used Character Map and the arial font, scrolled down past '~' and the others to the greek alphabet. Capitol Xi, ?, worked best for me, but I didn't check to see which was the actual 'lowest' in the sort.

jquery UI dialog: how to initialize without a title bar?

I think the cleanest way of doing it would be to create a new myDialog widget, consisting of the dialog widget minus the title bar code. Excising the title bar code looks straightforward.

Console logging for react?

If you want to log inside JSX you can create a dummy component
which plugs where you wish to log:

const Console = prop => (
  ,null // ? React components must return something 

// Some component with JSX and a logger inside
const App = () => 
    <p>imagine this is some component</p>
    <Console log='foo' />
    <p>imagine another component</p>
    <Console warn='bar' />

// Render 
  <App />,
<script src=""></script>
<script src=""></script>
<div id="react"></div>

How to see data from .RData file?

you can try

isfar <- get(load('c:/users/isfar.Rdata'))

this will assign the variable in isfar.Rdata to isfar . After this assignment, you can use str(isfar) or ls(isfar) or head(isfar) to get a rough look of the isfar.

How do I get the entity that represents the current user in Symfony2?

The thread is a bit old but i think this could probably save someone's time ...

I ran into the same problem as the original question, that the type is showed as Symfony\Component\Security\Core\User\User

It eventually turned out that i was logged in using an in memory user

my security.yml looks something like this

                providers: [in_memory, fos_userbundle]
            id: fos_user.user_manager
                    user:  { password: userpass, roles: [ 'ROLE_USER' ] }
                    admin: { password: adminpass, roles: [ 'ROLE_ADMIN', 'ROLE_SONATA_ADMIN' ] }

the in_memory user type is always Symfony\Component\Security\Core\User\User if you want to use your own entity, log in using that provider's user.

Thanks, hj

Insert current date in datetime format mySQL

Try this instead

$date = date('Y-m-d H:i:s');

How to assign pointer address manually in C programming language?

Your code would be like this:

int *p = (int *)0x28ff44;

int needs to be the type of the object that you are referencing or it can be void.

But be careful so that you don't try to access something that doesn't belong to your program.

DataTables fixed headers misaligned with columns in wide tables

I am having the same issue on IE9.

I will just use a RegExp to strip all the white spaces before writing the HTML to the page.

var Tables=$('##table_ID').html();
var expr = new RegExp('>[ \t\r\n\v\f]*<', 'g');
Tables= Tables.replace(expr, '><');
oTable = $('##table_ID').dataTable( {
  "bPaginate": false,
  "bLengthChange": false,
  "bFilter": false,
  "bSort": true,
  "bInfo": true,
  "bAutoWidth": false,
  "sScrollY": ($(window).height() - 320),
  "sScrollX": "100%",
  "sDom": 'rt<"bottom"i flp>'
} );

How can I pass a member function where a free function is expected?

Not sure why this incredibly simple solution has been passed up:

#include <stdio.h>

class aClass
    void aTest(int a, int b)
        printf("%d + %d = %d\n", a, b, a + b);

template<class C>
void function1(void (C::*function)(int, int), C& c)
    (c.*function)(1, 1);
void function1(void (*function)(int, int)) {
  function(1, 1);

void test(int a,int b)
    printf("%d - %d = %d\n", a , b , a - b);

int main (int argc, const char* argv[])
    aClass a;

    function1<aClass>(&aClass::aTest, a);
    return 0;


1 - 1 = 0
1 + 1 = 2

How to hide the soft keyboard from inside a fragment?

this will be work in my case when in tabs i switch from one fragment to another fragments

public void setUserVisibleHint(boolean isVisibleToUser) {
    if (isVisibleToUser) {
        try {
            InputMethodManager mImm = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
            mImm.hideSoftInputFromWindow(getView().getWindowToken(), 0);
            mImm.hideSoftInputFromWindow(getActivity().getCurrentFocus().getWindowToken(), 0);
        } catch (Exception e) {
            Log.e(TAG, "setUserVisibleHint: ", e);

Exposing a port on a live Docker container

Here's what I would do:

  • Commit the live container.
  • Run the container again with the new image, with ports open (I'd recommend mounting a shared volume and opening the ssh port as well)
sudo docker ps 
sudo docker commit <containerid> <foo/live>
sudo docker run -i -p 22 -p 8000:80 -m /data:/data -t <foo/live> /bin/bash

How to run certain task every day at a particular time using ScheduledExecutorService?

Have you considered using something like Quartz Scheduler? This library has a mechanism for scheduling tasks to run at a set period of time every day using a cron like expression (take a look at CronScheduleBuilder).

Some example code (not tested):

public class GetDatabaseJob implements InterruptableJob
    public void execute(JobExecutionContext arg0) throws JobExecutionException

public class Example
    public static void main(String[] args)
        JobDetails job = JobBuilder.newJob(GetDatabaseJob.class);

        // Schedule to run at 5 AM every day
        ScheduleBuilder scheduleBuilder = 
                CronScheduleBuilder.cronSchedule("0 0 5 * * ?");
        Trigger trigger = TriggerBuilder.newTrigger().

        Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
        scheduler.scheduleJob(job, trigger);


There's a bit more work upfront, and you may need to rewrite your job execution code, but it should give you more control over how you want you job to run. Also it would be easier to change the schedule should you need to.

How to properly create composite primary keys - MYSQL

Composite primary keys are what you want where you want to create a many to many relationship with a fact table. For example, you might have a holiday rental package that includes a number of properties in it. On the other hand, the property could also be available as a part of a number of rental packages, either on its own or with other properties. In this scenario, you establish the relationship between the property and the rental package with a property/package fact table. The association between a property and a package will be unique, you will only ever join using property_id with the property table and/or package_id with the package table. Each relationship is unique and an auto_increment key is redundant as it won't feature in any other table. Hence defining the composite key is the answer.

How to use auto-layout to move other views when a view is hidden?

I think this is the most simple answer. Please verify that it works:

        StackFullView.layer.isHidden = true
        Task_TopSpaceSections.constant = 0.   //your constraint of top view

check here

Using union and count(*) together in SQL query

  SELECT name FROM results
  SELECT name FROM archive_results
) AS tem

Differences between time complexity and space complexity?

There is a well know relation between time and space complexity.

First of all, time is an obvious bound to space consumption: in time t you cannot reach more than O(t) memory cells. This is usually expressed by the inclusion

                            DTime(f) ? DSpace(f)

where DTime(f) and DSpace(f) are the set of languages recognizable by a deterministic Turing machine in time (respectively, space) O(f). That is to say that if a problem can be solved in time O(f), then it can also be solved in space O(f).

Less evident is the fact that space provides a bound to time. Suppose that, on an input of size n, you have at your disposal f(n) memory cells, comprising registers, caches and everything. After having written these cells in all possible ways you may eventually stop your computation, since otherwise you would reenter a configuration you already went through, starting to loop. Now, on a binary alphabet, f(n) cells can be written in 2^f(n) different ways, that gives our time upper bound: either the computation will stop within this bound, or you may force termination, since the computation will never stop.

This is usually expressed in the inclusion

                          DSpace(f) ? Dtime(2^(cf))

for some constant c. the reason of the constant c is that if L is in DSpace(f) you only know that it will be recognized in Space O(f), while in the previous reasoning, f was an actual bound.

The above relations are subsumed by stronger versions, involving nondeterministic models of computation, that is the way they are frequently stated in textbooks (see e.g. Theorem 7.4 in Computational Complexity by Papadimitriou).


A ClassCastException ocurrs when you try to cast an instance of an Object to a type that it is not. Casting only works when the casted object follows an "is a" relationship to the type you are trying to cast to. For Example

Apple myApple = new Apple();
Fruit myFruit = (Fruit)myApple;

This works because an apple 'is a' fruit. However if we reverse this.

Fruit myFruit = new Fruit();
Apple myApple = (Apple)myFruit;

This will throw a ClasCastException because a Fruit is not (always) an Apple.

It is good practice to guard any explicit casts with an instanceof check first:

if (myApple instanceof Fruit) {
  Fruit myFruit = (Fruit)myApple;

How to use continue in jQuery each() loop?

We can break the $.each() loop at a particular iteration by making the callback function return false. Returning non-false is the same as a continue statement in a for loop; it will skip immediately to the next iteration. -- jQuery.each() | jQuery API Documentation

Simple way to query connected USB devices info in Python?

If you are working on windows, you can use pywin32 (old link: see update below).

I found an example here:

import win32com.client

wmi = win32com.client.GetObject ("winmgmts:")
for usb in wmi.InstancesOf ("Win32_USBHub"):
    print usb.DeviceID

Update Apr 2020:

'pywin32' release versions from 218 and up can be found here at github. Current version 227.

Should I use `import os.path` or `import os`?

Definitive answer: import os and use os.path. do not import os.path directly.

From the documentation of the module itself:

>>> import os
>>> help(os.path)
Instead of importing this module directly, import os and refer to
this module as os.path.  The "os.path" name is an alias for this
module on Posix systems; on other systems (e.g. Mac, Windows),
os.path provides the same operations in a manner specific to that
platform, and is an alias to another module (e.g. macpath, ntpath).

read input separated by whitespace(s) or newline...?

the user pressing enter or spaces is the same.

int count = 5;
int list[count]; // array of known length
cout << "enter the sequence of " << count << " numbers space separated: ";
// user inputs values space separated in one line.  Inputs more than the count are discarded.
for (int i=0; i<count; i++) {
    cin >> list[i];

Java enum - why use toString instead of name

It really depends on what you want to do with the returned value:

  • If you need to get the exact name used to declare the enum constant, you should use name() as toString may have been overriden
  • If you want to print the enum constant in a user friendly way, you should use toString which may have been overriden (or not!).

When I feel that it might be confusing, I provide a more specific getXXX method, for example:

public enum Fields {
    LAST_NAME("Last Name"), FIRST_NAME("First Name");

    private final String fieldDescription;

    private Fields(String value) {
        fieldDescription = value;

    public String getFieldDescription() {
        return fieldDescription;

Do you recommend using semicolons after every statement in JavaScript?

Yes, you should use semicolons after every statement in JavaScript.

connecting to MySQL from the command line

Use the following command to get connected to your MySQL database

mysql -u USERNAME -h HOSTNAME -p

Subtract days, months, years from a date in JavaScript

I have a simpler answer, which works perfectly for days; for months, it's +-2 days:

let today=new Date();
const days_to_subtract=30;
let new_date= new Date(today.valueOf()-(days_to_subtract*24*60*60*1000));

You get the idea - for months, multiply by 30; but that will be +-2 days.

Hidden TextArea

An <input type=hidden> element is not a hidden input box. It is simply a form field that has a value set via markup or via scripting, not via user input. You can use it for multi-line data too, e.g.

<input type=hidden name=stuff value=
world, how
are you?">

If the value contains the Ascii quotation mark ("), then, as for any HTML attribute, you need to use Ascii apostrophes (') as attribute value delimites or escape the quote as &quot;, e.g.

<input type=hidden name=stuff value="A &quot;funny&quot; example">

ValidateRequest="false" doesn't work in Asp.Net 4

There is a way to turn the validation back to 2.0 for one page. Just add the below code to your web.config:

    <location path="XX/YY">
            <httpRuntime requestValidationMode="2.0" />

    the rest of your configuration


SSL certificate rejected trying to access GitHub over HTTPS behind firewall

I needed two things:

  1. go to cygwin setup and include the package 'ca-certificates' (it is under Net) (as indicated elsewhere).

  2. Tell git where to find the installed certificates:

    GIT_SSL_CAINFO=/usr/ssl/certs/ca-bundle.crt GIT_CURL_VERBOSE=1 git ...

    (Verbose option is not needed)

    Or storing the option permanently:

    git config --global http.sslCAinfo /usr/ssl/certs/ca-bundle.crt

    git ...

Insert current date/time using now() in a field using MySQL/PHP

NOW() normally works in SQL statements and returns the date and time. Check if your database field has the correct type (datetime). Otherwise, you can always use the PHP date() function and insert:

date('Y-m-d H:i:s')

But I wouldn't recommend this.

How to efficiently use try...catch blocks in PHP

in a single try catch block you can do all the thing the best practice is to catch the error in different catch block if you want them to show with their own message for particular errors.

how to store Image as blob in Sqlite & how to retrieve it?

Here the code i used for my app

This code will take a image from url and convert is to a byte array

byte[] logoImage = getLogoImage(IMAGEURL);

private byte[] getLogoImage(String url){
     try {
             URL imageUrl = new URL(url);
             URLConnection ucon = imageUrl.openConnection();

             InputStream is = ucon.getInputStream();
             BufferedInputStream bis = new BufferedInputStream(is);

             ByteArrayBuffer baf = new ByteArrayBuffer(500);
             int current = 0;
             while ((current = != -1) {
                  baf.append((byte) current);

             return baf.toByteArray();
     } catch (Exception e) {
          Log.d("ImageManager", "Error: " + e.toString());
     return null;

To save the image to db i used this code.

 public void insertUser(){
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        String delSql = "DELETE FROM ACCOUNTS";
        SQLiteStatement delStmt = db.compileStatement(delSql);

        String sql = "INSERT INTO ACCOUNTS (account_id,account_name,account_image) VALUES(?,?,?)";
        SQLiteStatement insertStmt = db.compileStatement(sql);
        insertStmt.bindString(1, Integer.toString(this.accId));
        insertStmt.bindBlob(3, this.accImage);

To retrieve the image back this is code i used.

public Account getCurrentAccount() {
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    String sql = "SELECT * FROM ACCOUNTS";
    Cursor cursor = db.rawQuery(sql, new String[] {});

        this.accId  = cursor.getInt(0);
        this.accName = cursor.getString(1);
        this.accImage = cursor.getBlob(2);
    if (cursor != null && !cursor.isClosed()) {
    if(cursor.getCount() == 0){
        return null;
    } else {
        return this;

Finally to load this image to a imageview

logoImage.setImageBitmap(BitmapFactory.decodeByteArray( currentAccount.accImage, 

AngularJS view not updating on model change

Do not use $scope.$apply() angular already uses it and it can result in this error

$rootScope:inprog Action Already In Progress

if you use twice, use $timeout or interval

Android: Changing Background-Color of the Activity (Main View)

You can also try and provide an Id for the main layout and change the background of that through basic manipulation and retrieval. E.g:

<LinearLayout xmlns:android=""

Which can then be followed by accessing through Pretty basic and I hope this does help :)

How do I perform query filtering in django templates

You can't do this, which is by design. The Django framework authors intended a strict separation of presentation code from data logic. Filtering models is data logic, and outputting HTML is presentation logic.

So you have several options. The easiest is to do the filtering, then pass the result to render_to_response. Or you could write a method in your model so that you can say {% for object in data.filtered_set %}. Finally, you could write your own template tag, although in this specific case I would advise against that.

Parse an URL in JavaScript

You can use the jquery plugin $.url("?img_id") will return 33

When should I use double or single quotes in JavaScript?

You can use single quotes or double quotes.

This enables you for example to easily nest JavaScript content inside HTML attributes, without the need to escape the quotes. The same is when you create JavaScript with PHP.

The general idea is: if it is possible use such quotes that you won't need to escape.

Less escaping = better code.

Angular 2 declaring an array of objects

type NumberArray = Array<{id: number, text: string}>;

const arr: NumberArray = [
    {id: 0, text: 'Number 0'},
    {id: 1, text: 'Number 1'},
    {id: 2, text: 'Number 2'},
    {id: 3, text: 'Number 3 '},
    {id: 4, text: 'Number 4 '},
    {id: 5, text: 'Number 5 '},

How to check currently internet connection is available or not in android

This will tell if you're connected to a network:

boolean connected = false;
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    if(connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED || 
            connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
        //we are connected to a network
        connected = true;
        connected = false;

Warning: If you are connected to a WiFi network that doesn't include internet access or requires browser-based authentication, connected will still be true.

You will need this permission in your manifest:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

How do the major C# DI/IoC frameworks compare?

While a comprehensive answer to this question takes up hundreds of pages of my book, here's a quick comparison chart that I'm still working on:

A table explaining difference between several DICs

SQL Server Escape an Underscore

Obviously @Lasse solution is right, but there's another way to solve your problem: T-SQL operator LIKE defines the optional ESCAPE clause, that lets you declare a character which will escape the next character into the pattern.

For your case, the following WHERE clauses are equivalent:

WHERE username LIKE '%[_]d';            -- @Lasse solution
WHERE username LIKE '%$_d' ESCAPE '$';
WHERE username LIKE '%^_d' ESCAPE '^';

Disable single warning error

If you want to disable unreferenced local variable write in some header

template<class T>
void ignore (const T & ) {}

and use

catch(const Except & excpt) {
    ignore(excpt); // No warning
    // ...  

Javascript receipt printing using POS Printer

I printed form javascript to a Star Micronics Webprnt TSP 654ii thermal printer. This printer is a wired network printer and you can draw the content to a HTML canvas and make a HTTP request to print. The only caveat is that, this printer does not support HTTPS protocol yet, so you will get a mixed content warning in production. Contacted Star micronics support and they said, they are working on HTTPS support and soon a firmware upgrade will be available. Also, looks like Epson Omnilink TM-88V printer with TM-I will support javascript printing.

Here is a sample code:

href="javascript:" vs. href="javascript:void(0)"

This method seems ok in all browsers, if you set the onclick with a jQuery event:

<a href="javascript:;">Click me!</a>

As said before, href="#" with change the url hash and can trigger data re/load if you use a History (or ba-bbq) JS plugin.

PowerShell array initialization

Or try this an idea. Works with powershell 5.0+.


Copy entire contents of a directory to another using php

Full thanks must go to Felix Kling for his excellent answer which I have gratefully used in my code. I offer a small enhancement of a boolean return value to report success or failure:

function recurse_copy($src, $dst) {

  $dir = opendir($src);
  $result = ($dir === false ? false : true);

  if ($result !== false) {
    $result = @mkdir($dst);

    if ($result === true) {
      while(false !== ( $file = readdir($dir)) ) { 
        if (( $file != '.' ) && ( $file != '..' ) && $result) { 
          if ( is_dir($src . '/' . $file) ) { 
            $result = recurse_copy($src . '/' . $file,$dst . '/' . $file); 
          }     else { 
            $result = copy($src . '/' . $file,$dst . '/' . $file); 

  return $result;

Add a fragment to the URL without causing a redirect?

For straight HTML, with no JavaScript required:

<a href="#something">Add '#something' to URL</a>

Or, to take your question more literally, to just add '#' to the URL:

<a href="#">Add '#' to URL</a>

How to use boolean datatype in C?

C99 has a bool type. To use it,

#include <stdbool.h>

ASP.Net MVC Redirect To A Different View

 if (true)
   return View();
   return View("another view name");

Git: can't undo local changes (error: path ... is unmerged)

You did it the wrong way around. You are meant to reset first, to unstage the file, then checkout, to revert local changes.

Try this:

$ git reset foo/bar.txt
$ git checkout foo/bar.txt

How to generate a Makefile with source in sub-directories using just one makefile

This is another trick.

In main 'Makefile' define SRCDIR for each source dir and include '' for each value of SRCDIR. In each source dir put file '' with list of source files and compile options for some of them. In main 'Makefile' one can define compile options and exclude files for each value of SRCDIR.


PRG             := prog-name

OPTIMIZE        := -O2 -fomit-frame-pointer

CFLAGS += -finline-functions-called-once
LDFLAGS += -Wl,--gc-section,--reduce-memory-overheads,--relax

.DEFAULT_GOAL   := hex

OBJDIR          := obj

MK_DIRS         := $(OBJDIR)

SRCDIR          := .

SRCDIR := crc


CC              := avr-gcc -mmcu=$(MCU_TARGET) -I.
OBJCOPY         := avr-objcopy
OBJDUMP         := avr-objdump

C_FLAGS         := $(CFLAGS) $(REGS) $(OPTIMIZE)
AS_FLAGS        := $(ASFLAGS)
LD_FLAGS        := $(LDFLAGS) -Wl,-Map,$(OBJDIR)/$(PRG).map

C_OBJS          := $(C_SRC:%.c=$(OBJDIR)/%.o)
CPP_OBJS        := $(CPP_SRC:%.cpp=$(OBJDIR)/%.o)
AS_OBJS         := $(AS_SRC:%.S=$(OBJDIR)/%.o)

C_DEPS          := $(C_OBJS:%=%.d)
CPP_DEPS        := $(CPP_OBJS:%=%.d)
AS_DEPS         := $(AS_OBJS:%=%.d)

OBJS            := $(C_OBJS) $(CPP_OBJS) $(AS_OBJS)
DEPS            := $(C_DEPS) $(CPP_DEPS) $(AS_DEPS)

hex:  $(PRG).hex
lst:  $(PRG).lst

$(OBJDIR)/$(PRG).elf : $(OBJS)
    $(CC) $(C_FLAGS) $(LD_FLAGS) $^ -o $@

%.lst: $(OBJDIR)/%.elf
    -@rm $@ 2> /dev/nul
    $(OBJDUMP) -h -s -S $< > $@

%.hex: $(OBJDIR)/%.elf
    -@rm $@ 2> /dev/nul
    $(OBJCOPY) -j .text -j .data -O ihex $< $@

$(C_OBJS) : $(OBJDIR)/%.o : %.c Makefile
    $(CC) -MMD -MF [email protected] -c $(C_FLAGS) $(C_FLAGS_$(call clear_name,$<)) $< -o $@
    @sed -e 's,.*:,SRC_FILES += ,g' < [email protected] > [email protected]
    @sed -e "\$$s/$$/ $(subst /,\/,$(dir $<))\n/" < [email protected] >> [email protected]
    @sed -e 's,^[^:]*: *,,' -e 's,^[ \t]*,,' -e 's, \\$$,,' -e 's,$$, :,' < [email protected] >> [email protected]
    -@rm -f [email protected]

$(CPP_OBJS) : $(OBJDIR)/%.o : %.cpp Makefile
    $(CC) -MMD -MF [email protected] -c $(CPP_FLAGS) $(CPP_FLAGS_$(call clear_name,$<)) $< -o $@
    @sed -e 's,.*:,SRC_FILES += ,g' < [email protected] > [email protected]
    @sed -e "\$$s/$$/ $(subst /,\/,$(dir $<))\n/" < [email protected] >> [email protected]
    @sed -e 's,^[^:]*: *,,' -e 's,^[ \t]*,,' -e 's, \\$$,,' -e 's,$$, :,' < [email protected] >> [email protected]
    -@rm -f [email protected]

$(AS_OBJS) : $(OBJDIR)/%.o : %.S Makefile
    $(CC) -MMD -MF [email protected] -c $(AS_FLAGS) $(AS_FLAGS_$(call clear_name,$<)) $< -o $@
    @sed -e 's,.*:,SRC_FILES += ,g' < [email protected] > [email protected]
    @sed -e "\$$s/$$/ $(subst /,\/,$(dir $<))\n/" < [email protected] >> [email protected]
    @sed -e 's,^[^:]*: *,,' -e 's,^[ \t]*,,' -e 's, \\$$,,' -e 's,$$, :,' < [email protected] >> [email protected]
    -@rm -f [email protected]

    -@rm -rf $(OBJDIR)/$(PRG).elf
    -@rm -rf $(PRG).lst $(OBJDIR)/$(PRG).map
    -@rm -rf $(PRG).hex $(PRG).bin $(PRG).srec
    -@rm -rf $(PRG)_eeprom.hex $(PRG)_eeprom.bin $(PRG)_eeprom.srec
    -@rm -rf $(MK_DIRS:%=%/*.o) $(MK_DIRS:%=%/*.o.d)
    -@rm -f tags cscope.out

#   -rm -rf $(OBJDIR)/*
#   -rm -rf $(OBJDIR)
#   -rm $(PRG)

tag: tags
tags: $(SRC_FILES)
    if [ -e tags ] ; then ctags -u $? ; else ctags $^ ; fi
    cscope -U -b $^

# include dep. files
ifneq "$(MAKECMDGOALS)" "clean"
-include $(DEPS)

# Create directory
$(shell mkdir $(MK_DIRS) 2>/dev/null)


C_SRC :=

include $(SRCDIR)/

clear_name = $(subst /,_,$(1))

define rename_var
$(2)_$(call clear_name,$(SRCDIR))_$(call clear_name,$(1)) := \
    $($(subst _,,$(2))_$(call clear_name,$(SRCDIR))) $($(call clear_name,$(1)))
$(call clear_name,$(1)) :=

define proc_lang


ifneq ($(strip $($(1)_ONLY_FILES)),)
$(1)_SRC := $(filter $($(1)_ONLY_FILES),$($(1)_SRC))

ifneq ($(strip $(ONLY_FILES)),)
$(1)_SRC := $(filter $(ONLY_FILES),$($(1)_SRC))
$(1)_SRC := $(filter-out $(EXCLUDE_FILES),$($(1)_SRC))


$(1)_ONLY_FILES :=
$(foreach name,$($(1)_SRC),$(eval $(call rename_var,$(name),$(1)_FLAGS)))
$(foreach name,$(ORIGIN_SRC_FILES),$(eval $(call clear_name,$(name)) :=))


$(foreach lang,C CPP AS, $(eval $(call proc_lang,$(lang))))


SAVE_C_SRC += $(C_SRC:%=$(SRCDIR)/%)



C_SRC   := main.c
AS_SRC  := timer.S

main.c += -DDEBUG


C_SRC    := byte-modbus-crc.c byte-crc8.c
AS_SRC   := modbus-crc.S crc8.S modbus-crc-table.S crc8-table.S

byte-modbus-crc.c += --std=gnu99
byte-crc8.c       += --std=gnu99

Get column index from column name in python pandas

For returning multiple column indices, I recommend using the pandas.Index method get_indexer, if you have unique labels:

df = pd.DataFrame({"pear": [1, 2, 3], "apple": [2, 3, 4], "orange": [3, 4, 5]})
df.columns.get_indexer(['pear', 'apple'])
# Out: array([0, 1], dtype=int64)

If you have non-unique labels in the index (columns only support unique labels) get_indexer_for. It takes the same args as get_indeder:

df = pd.DataFrame(
    {"pear": [1, 2, 3], "apple": [2, 3, 4], "orange": [3, 4, 5]}, 
    index=[0, 1, 1])
df.index.get_indexer_for([0, 1])
# Out: array([0, 1, 2], dtype=int64)

Both methods also support non-exact indexing with, f.i. for float values taking the nearest value with a tolerance. If two indices have the same distance to the specified label or are duplicates, the index with the larger index value is selected:

df = pd.DataFrame(
    {"pear": [1, 2, 3], "apple": [2, 3, 4], "orange": [3, 4, 5]},
    index=[0, .9, 1.1])
df.index.get_indexer([0, 1])
# array([ 0, -1], dtype=int64)

How to hide console window in python?

This will hide your console. Implement these lines in your code first to start hiding your console at first.

import win32gui, win32con

the_program_to_hide = win32gui.GetForegroundWindow()
win32gui.ShowWindow(the_program_to_hide , win32con.SW_HIDE)

Update May 2020 :

If you've got trouble on pip install win32con on Command Prompt, you can simply pip install pywin32.Then on your python script, execute import win32.lib.win32con as win32con instead of import win32con.

To show back your program again win32con.SW_SHOW works fine:

win32gui.ShowWindow(the_program_to_hide , win32con.SW_SHOW)

Assertion failure in dequeueReusableCellWithIdentifier:forIndexPath:

In Swift this problem can be solved by adding the following code in your



tableView.registerClass(UITableViewCell.classForKeyedArchiver(), forCellReuseIdentifier: "your_reuse_identifier")

Change icon-bar (?) color in bootstrap

The reason your CSS isn't working is because of specificity. The Bootstrap selector has a higher specificity than yours, so your style is completely ignored.

Bootstrap styles this with the selector: .navbar-default .navbar-toggle .icon-bar. This selector has a B specificity value of 3, whereas yours only has a B specificity value of 1.

Therefore, to override this, simply use the same selector in your CSS (assuming your CSS is included after Bootstrap's):

.navbar-default .navbar-toggle .icon-bar {
    background-color: black;

System.BadImageFormatException: Could not load file or assembly (from installutil.exe)

My issue was different. This occurred after an unexpected shutdown of my windows 7 machine. I performed a clean solution and it ran as expected.

Python Iterate Dictionary by Index

You can iterate over keys and get values by keys:

for key in dict.iterkeys():
    print key, dict[key]

You can iterate over keys and corresponding values:

for key, value in dict.iteritems():
    print key, value

You can use enumerate if you want indexes (remember that dictionaries don't have an order):

>>> for index, key in enumerate(dict):
...     print index, key
0 orange
1 mango
2 apple

How do you grep a file and get the next 5 lines

You want:

grep -A 5 '19:55' file

From man grep:

Context Line Control

-A NUM, --after-context=NUM

Print NUM lines of trailing context after matching lines.  
Places a line containing a gup separator (described under --group-separator) 
between contiguous groups of matches.  With the -o or --only-matching
option, this has no effect and a warning is given.

-B NUM, --before-context=NUM

Print NUM lines of leading context before matching lines.  
Places a line containing a group separator (described under --group-separator) 
between contiguous groups of matches.  With the -o or --only-matching
option, this has no effect and a warning is given.

-C NUM, -NUM, --context=NUM

Print NUM lines of output context.  Places a line containing a group separator
(described under --group-separator) between contiguous groups of matches.  
With the -o or --only-matching option,  this  has  no effect and a warning
is given.


Use SEP as a group separator. By default SEP is double hyphen (--).


Use empty string as a group separator.

How do I set the default page of my application in IIS7?

If you want to do something like,User enter url "" & default page is displayed then I guess you have to set the default/home/welcome page attribute in IIS. But if user just enters "" and you still want to forward to your url, then you have write a line of code in the default page to forward to your desired url. This default page should be in root directory of your application, so will load which will redirect the user to your desired url

html select option SELECTED

foreach($array as $value=>$name)
    if($value == $_GET['sel'])
         echo "<option selected='selected' value='".$value."'>".$name."</option>";
         echo "<option value='".$value."'>".$name."</option>";

open program minimized via command prompt

Local Windows 10 ActiveMQ server :

@echo off
start /min "" "C:\Install\apache-activemq\5.15.10\bin\win64\activemq.bat" start

How do I get the day month and year from a Windows cmd.exe script?

echo %Date:~7,2% gets current day

7 is starting position 2 number of digits to display

echo %Date:~7,2% gets current day

echo %Date:~4,2% gets current month

echo %Date:~10,4% gets current year

How to embed a Google Drive folder in a website

At the time of writing this answer, there was no method to embed which let the user navigate inside folders and view the files without her leaving the website (the method in other answers, makes everything open in a new tab on google drive website), so I made my own tool for it. To embed a drive, paste the iframe code below in your HTML:

<iframe src="" style="border:none;" width="100%"></iframe>

In the above code, you need to have your own API key and the folder ID. You can set the height as per your wish.

To get the API key:

1.) Go to Create a new project.

2.) From the menu button, go to 'APIs and Services' --> 'Dashboard' --> Click on 'Enable APIs and Services'.

3.) Search for 'Google Drive API', enable it. Then go to "credentials' tab, and create credentials. Keep your API key unrestricted.

4.) Copy the newly generated API key.

To get the folder ID:

1.)Go to the google drive folder you want to embed (for example, [this is not a real folder]) Ensure that the folder is publicly shared and visible to anyone.

2.) Copy the part after 'folders/', this is your folder ID.

Now put both the API key and folder id in the above code and embed.

Note: To hide the download button for files, add '&allowdl=no' at the end of the iframe's src URL.

I made the widget keeping mobile users in mind, however it suits both mobile and desktop. If you run into issues, leave a comment here. I have attached some screenshots of the content of the iframe here.

The file preview looks like this The content of the iframe looks like this

Input jQuery get old value before onchange and get value after on change

I have found a solution that works even with "Select2" plugin:

function functionName() {
  $('html').on('change', 'select.some-class', function() {
    var newValue = $(this).val();
    var oldValue = $(this).attr('data-val');
    if ( $.isNumeric(oldValue) ) { // or another condition
      // do something
    $(this).attr('data-val', newValue);

How do I make a WPF TextBlock show my text on multiple lines?

Nesting a stackpanel will cause the textbox to wrap properly:

<Viewbox Margin="120,0,120,0">
    <StackPanel Orientation="Vertical" Width="400">
        <TextBlock x:Name="subHeaderText" 
                   Text="Lorem ipsum dolor, lorem isum dolor,Lorem ipsum dolor sit amet, lorem ipsum dolor sit amet " />

Action bar navigation modes are deprecated in Android L

I had the same problem and this solution suited me quite nicely:

In the layout xml file that contains the viewpager, add the a PagerTabStrip as shown:

    android:paddingBottom="5dp" />

To control page titles, add a switch statement to your ViewPager file:

public CharSequence getPageTitle(int position)
    switch (position)
    case 0:
        return "Page 1";

    case 1:
        return "Page 2";

    case 2:
        return "Page 3";


    return null;

XPath: select text node

Having the following XML:


How do I select either the first or the second text node via XPath?



This selects all text-node children of the top element (named "node") of the XML document.


This selects the first text-node child of the top element (named "node") of the XML document.


This selects the second text-node child of the top element (named "node") of the XML document.


This selects the someInteger-th text-node child of the top element (named "node") of the XML document. It is equivalent to the following XPath expression:

/node/text()[position() = someInteger]

Open application after clicking on Notification

This is the way that I have approached.

public class AppFCMService extends FirebaseMessagingService {

    private final static String TAG = "FCM Message";
    String notify, requstId, Notification;
    PendingIntent pendingIntent;

    public void onMessageReceived(RemoteMessage remoteMessage) {
        Log.d(TAG, "From: " + remoteMessage.getFrom());
        Log.d(TAG, "Notification Message Body: " + remoteMessage.getNotification().getBody());
        //split string and getting order id from notification
        String Str = remoteMessage.getNotification().getBody();
        String[] tmp;
        tmp = Str.split(" ");
        String temp1 = tmp[0];
        String temp2 = tmp[1];
        String id = tmp[2];
        notify = temp1 + " " + temp2;
        requstId = id;

    private void showNotification(String messageBody) {
        // check whether session has been initiated or not
        if (new SessionHelper(getApplicationContext()).isLoggedIn()) {

            if (notify.equalsIgnoreCase("Travel request")) {

                Intent intent = new Intent(this, ViewTravelDetailsActivity.class);
                intent.putExtra("TravelRequestID", requstId);
                intent.putExtra("BackPress", "Notify");
                pendingIntent = PendingIntent.getActivity(this, 0, intent,

            } else if (notify.equalsIgnoreCase("Timesheet replied")) {

                Intent intent = new Intent(this, ViewReplyActivity.class);
                intent.putExtra("timesheetActivityID", requstId);
                intent.putExtra("BackPress", "Notify");
                intent.putExtra("RealmData", "DeleteRealm");
                intent.putExtra("isToday", "true");
                pendingIntent = PendingIntent.getActivity(this, 0, intent,
            } else {

                Intent intent = new Intent(this, Dashboard.class);
                intent.putExtra("timesheetActivityID", requstId);
                pendingIntent = PendingIntent.getActivity(this, 0, intent,
        } else {

            Intent intent = new Intent(this, LoginActivity.class);
            intent.putExtra("timesheetActivityID", requstId);
            pendingIntent = PendingIntent.getActivity(this, 0, intent,

        Bitmap notifyImage = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

How to check if the user can go back in browser history or not

There is another near perfect solution, taken from another SO answer:

if( (1 < history.length) && document.referrer ) {
else {
    // If you can't go back in history, you could perhaps close the window ?

Someone reported that it does not work when using target="_blank" but it seems to work for me on Chrome.

PowerShell script to check the status of a URL

I recently set up a script that does this.

As David Brabant pointed out, you can use the System.Net.WebRequest class to do an HTTP request.

To check whether it is operational, you should use the following example code:

# First we create the request.
$HTTP_Request = [System.Net.WebRequest]::Create('')

# We then get a response from the site.
$HTTP_Response = $HTTP_Request.GetResponse()

# We then get the HTTP code as an integer.
$HTTP_Status = [int]$HTTP_Response.StatusCode

If ($HTTP_Status -eq 200) {
    Write-Host "Site is OK!"
Else {
    Write-Host "The Site may be down, please check!"

# Finally, we clean up the http request by closing it.
If ($HTTP_Response -eq $null) { } 
Else { $HTTP_Response.Close() }

Quickly create large file on a Windows system

Temp files should be stored in the Windows Temp Folder. Based on the answer from Rod you can use the following one liner to create a 5 GB temp file which returns the filename

[System.IO.Path]::GetTempFileName() | % { [System.IO.File]::Create($_).SetLength(5gb).Close;$_ } | ? { $_ }


  • [System.IO.Path]::GetTempFileName() generates a random filename with random extension in the Windows Temp Folder
  • The Pipeline is used to pass the name to [System.IO.File]::Create($_) which creates the file
  • The file name is set to the newly created file with .SetLength(5gb). I was a bit surprised to discover, that PowerShell supports Byte Conversion, which is really helpful.
  • The file handle needs to be closed with .close to allow other applications to access it
  • With ;$_ the filename is returned and with | ? { $_ } it is ensured that only the filename is returned and not the empty string returned by [System.IO.File]::Create($_)

iptables block access to port 8000 except from IP address

This question should be on Server Fault. Nevertheless, the following should do the trick, assuming you're talking about TCP and the IP you want to allow is

iptables -A INPUT -p tcp --dport 8000 -s -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP

Custom Authentication in ASP.Net-Core

I would like to add something to brilliant @AmiNadimi answer for everyone who going implement his solution in .NET Core 3:

First of all, you should change signature of SignIn method in UserManager class from:

public async void SignIn(HttpContext httpContext, UserDbModel user, bool isPersistent = false)


public async Task SignIn(HttpContext httpContext, UserDbModel user, bool isPersistent = false)

It's because you should never use async void, especially if you work with HttpContext. Source: Microsoft Docs

The last, but not least, your Configure() method in Startup.cs should contains app.UseAuthorization and app.UseAuthentication in proper order:

if (env.IsDevelopment())
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see

app.UseEndpoints(endpoints =>
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");

"Server Tomcat v7.0 Server at localhost failed to start" without stack trace while it works in terminal

To resolve this issue, you have to delete the .snap file located in the directory:


After deleting this file, you could start Eclipse with no problem.

checking for typeof error in JS

Or use this for different types of errors

function isError(val) {
  return (!!val && typeof val === 'object')
    && (( === '[object Error]')
      || (typeof val.message === 'string' && typeof === 'string'))

jQuery - Click event on <tr> elements with in a table and getting <td> element values

jQuery(document).ready(function() {
       alert("Click! "+ jQuery(this).find('td').html());

How to prevent form from being submitted?

var form = document.getElementById("idOfForm");
form.onsubmit = function() {
  return false;

Show Error on the tip of the Edit Text Android

you could use an onchange event to trigger a validation and then you can display a toast if this is enough for you

How to start working with GTest and CMake

Having done some more digging, I think my issue is something to do with the type of library I am building gtest into. When building gtest with CMake, if BUILD_SHARED_LIBS is un-checked, and I link my program against these .lib files I get the errors mentioned above. However, if BUILD_SHARED_LIBS is checked then I produce a set of .lib and .dll files. When now linking against these .lib files the program compiles, but when run complains that it can't find gtest.dll.

That is because you have to add -DGTEST_LINKED_AS_SHARED_LIBRARY=1 to compiler definitions in your project if you want to use gtest as a shared library.

You could also use the static libraries, provided you compiled it with gtest_force_shared_crt option on to eliminate errors you have seen.

I like the library but adding it to the project is a real pain. And you have no chance to do it right unless you dig (and hack) into the gtest cmake files. Shame. In particular I do not like the idea of adding gtest as a source. :)

Changing the browser zoom level

I would say not possible in most browsers, at least not without some additional plugins. And in any case I would try to avoid relying on the browser's zoom as the implementations vary (some browsers only zoom the fonts, others zoom the images, too etc). Unless you don't care much about user experience.

If you need a more reliable zoom, then consider zooming the page fonts and images with JavaScript and CSS, or possibly on the server side. The image and layout scaling issues could be addressed this way. Of course, this requires a bit more work.

How to set the image from drawable dynamically in android?

First of let's your image name is myimage. So what you have to do is that go to Drawable and save the image name myimage.

Now assume you know only image name and you need to access it. Use below snippet to access it,

what you did is correct , ensure you saved image name you are going to use inside coding.

public static int getResourceId(Context context, String name, String resourceType) {
    return context.getResources().getIdentifier(toResourceString(name), resourceType, context.getPackageName());

private static String toResourceString(String name) {
    return name.replace("(", "")
               .replace(")", "")
               .replace(" ", "_")
               .replace("-", "_")
               .replace("'", "")
               .replace("&", "")

In addition to it you should ensure that there is no empty spaces and case sensitives

How to access the contents of a vector from a pointer to the vector in C++?

There are a lot of solutions. For example you can use at() method.

*I assumed that you a looking for equivalent to [] operator.