Programs & Examples On #Jndi

The Java Naming and Directory Interface (JNDI) is a Java API for a directory service that allows Java software clients to discover and look up data and objects via a name.

The meaning of NoInitialContextException error

you need to use jboss-client.jar in your client project and you need to use jnp-client jar in your ejb project

Name [jdbc/mydb] is not bound in this Context

you put resource-ref in the description tag in web.xml

How do I connect to a Websphere Datasource with a given JNDI name?

To get a connection from a data source, the following code should work:

import java.sql.Connection;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

Context ctx = new InitialContext();
DataSource dataSource = ctx.lookup("java:comp/env/jdbc/xxxx");
Connection conn = dataSource.getConnection();

// use the connection


While you can look up a data source as defined in the Websphere Data Sources config (i.e. through the websphere console) directly, the lookup from java:comp/env/jdbc/xxxx means that there needs to be an entry in web.xml:


This means that data sources can be mapped on a per application bases and you don't need to change the name of the data source if you want to point your app to a different data source. This is useful when deploying the application to different servers (e.g. test, preprod, prod) which need to point to different databases.

How do a LDAP search/authenticate against this LDAP in Java

Another approach is using UnboundID. Its api is very readable and shorter

Create a Ldap Connection

public static LDAPConnection getConnection() throws LDAPException {
    // host, port, username and password
    return new LDAPConnection("com.example.local", 389, "[email protected]", "admin");

Get filter result

public static List<SearchResultEntry> getResults(LDAPConnection connection, String baseDN, String filter) throws LDAPSearchException {
    SearchResult searchResult;

    if (connection.isConnected()) {
        searchResult =, SearchScope.ONE, filter);

        return searchResult.getSearchEntries();

    return null;

Get all Oragnization Units and Containers

String baseDN = "DC=com,DC=example,DC=local";
String filter = "(&(|(objectClass=organizationalUnit)(objectClass=container)))";

LDAPConnection connection = getConnection();        
List<SearchResultEntry> results = getResults(connection, baseDN, filter);

Get a specific Organization Unit

String baseDN = "DC=com,DC=example,DC=local";
String dn = "CN=Users,DC=com,DC=example,DC=local";

String filterFormat = "(&(|(objectClass=organizationalUnit)(objectClass=container))(distinguishedName=%s))";
String filter = String.format(filterFormat, dn);

LDAPConnection connection =  getConnection();

List<SearchResultEntry> results = getResults(connection, baseDN, filter);

Get all users under an Organizational Unit

String baseDN = "CN=Users,DC=com,DC=example,DC=local";
String filter = "(&(objectClass=user)(!(objectCategory=computer)))";

LDAPConnection connection =  getConnection();       
List<SearchResultEntry> results = getResults(connection, baseDN, filter);

Get a specific user under an Organization Unit

String baseDN = "CN=Users,DC=com,DC=example,DC=local";
String userDN = "CN=abc,CN=Users,DC=com,DC=example,DC=local";

String filterFormat = "(&(objectClass=user)(distinguishedName=%s))";
String filter = String.format(filterFormat, userDN);

LDAPConnection connection =  getConnection();
List<SearchResultEntry> results = getResults(connection, baseDN, filter);

Display result

for (SearchResultEntry e : results) {
    System.out.println("name: " + e.getAttributeValue("name"));

What is JNDI? What is its basic use? When is it used?

The best explanation to me is given here

What is JNDI

It is an API to providing access to a directory service, that is, a service mapping name (strings) with objects, reference to remote objects or simple data. This is called binding. The set of bindings is called the context. Applications use the JNDI interface to access resources.

To put it very simply, it is like a hashmap with a String key and Object values representing resources on the web.

What Issues Does JNDI Solve

Without JNDI, the location or access information of remote resources would have to be hard-coded in applications or made available in a configuration. Maintaining this information is quite tedious and error prone.

If a resources has been relocated on another server, with another IP address, for example, all applications using this resource would have to be updated with this new information. With JNDI, this is not necessary. Only the corresponding resource binding has to be updated. Applications can still access it with its name and the relocation is transparent.

Configure hibernate to connect to database via JNDI Datasource

Inside applicationContext.xml file of a maven Hibernet web app project below settings worked for me.

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns=""
    xmlns:xsi="" xmlns:beans=""
    xmlns:context="" xmlns:tx=""

  <jee:jndi-lookup id="dataSource"
                 expected-type="javax.sql.DataSource" />

Hope It will help someone.Thanks!

What does java:comp/env/ do?


At the root context of the namespace is a binding with the name "comp", which is bound to a subtree reserved for component-related bindings. The name "comp" is short for component. There are no other bindings at the root context. However, the root context is reserved for the future expansion of the policy, specifically for naming resources that are tied not to the component itself but to other types of entities such as users or departments. For example, future policies might allow you to name users and organizations/departments by using names such as "java:user/alice" and "java:org/engineering".

In the "comp" context, there are two bindings: "env" and "UserTransaction". The name "env" is bound to a subtree that is reserved for the component's environment-related bindings, as defined by its deployment descriptor. "env" is short for environment. The J2EE recommends (but does not require) the following structure for the "env" namespace.

So the binding you did from spring or, for example, from a tomcat context descriptor go by default under java:comp/env/

For example, if your configuration is:

<bean id="someId" class="org.springframework.jndi.JndiObjectFactoryBean">
  <property name="jndiName" value="foo"/>

Then you can access it directly using:

Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup("java:comp/env/foo");

or you could make an intermediate step so you don't have to specify "java:comp/env" for every resource you retrieve:

Context ctx = new InitialContext();
Context envCtx = (Context)ctx.lookup("java:comp/env");
DataSource ds = (DataSource)envCtx.lookup("foo");

Cannot create JDBC driver of class ' ' for connect URL 'null' : I do not understand this exception

I can't see anything obviously wrong, but perhaps a different approach might help you debug it?

You could try specify your datasource in the per-application-context instead of the global tomcat one.

You can do this by creating a src/main/webapp/META-INF/context.xml (I'm assuming you're using the standard maven directory structure - if not, then the META-INF folder should be a sibling of your WEB-INF directory). The contents of the META-INF/context.xml file would look something like:

<?xml version="1.0" encoding="UTF-8"?>

<Context [optional other attributes as required]>

<Resource name="jdbc/PollDatasource" auth="Container"
          type="javax.sql.DataSource" driverClassName="org.apache.derby.jdbc.ClientDriver"
          username="suhail" password="suhail" maxActive="20" maxIdle="10" maxWait="-1"/>

Obviously the path and docBase would need to match your application's specific details.

Using this approach, you don't have to specify the datasource details in Tomcat's context.xml file. Although, if you have multiple applications talking to the same database, then your approach makes more sense.

At any rate, give this a whirl and see if it makes any difference. It might give us a clue as to what is going wrong with your approach.

How to lookup JNDI resources on WebLogic?

You should be able to simply do this:

Context context = new InitialContext();
dataSource = (javax.sql.DataSource) context.lookup("jdbc/myDataSource");

If you are looking it up from a remote destination you need to use the WL initial context factory like this:

Hashtable<String, String> h = new Hashtable<String, String>(7);
h.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
h.put(Context.PROVIDER_URL, pURL); //For example "t3://"
h.put(Context.SECURITY_PRINCIPAL, pUsername);
h.put(Context.SECURITY_CREDENTIALS, pPassword);

InitialContext context = new InitialContext(h);
dataSource = (javax.sql.DataSource) context.lookup("jdbc/myDataSource");


How to use JNDI DataSource provided by Tomcat in Spring?

Assuming you have a "sampleDS" datasource definition inside your tomcat configuration, you can add following lines to your applicationContext.xml to access the datasource using JNDI.

<jee:jndi-lookup expected-type="javax.sql.DataSource" id="springBeanIdForSampleDS" jndi-name="sampleDS"/>

You have to define the namespace and schema location for jee prefix using:



The error means that your are trying to look up JNDI name, that is not attached to any EJB component - the component with that name does not exist.

As far as dir structure is concerned: you have to create a JAR file with EJB components. As I understand you want to play with EJB 2.X components (at least the linked example suggests that) so the structure of the JAR file should be:

/com/mypackage/MyEJB.class /com/mypackage/MyEJBInterface.class /com/mypackage/etc... etc... java classes /META-INF/ejb-jar.xml /META-INF/jboss.xml

The JAR file is more or less ZIP file with file extension changed from ZIP to JAR.

BTW. If you use JBoss 5, you can work with EJB 3.0, which are much more easier to configure. The simplest component is

public class MyEJB implements MyEJBInterface{
   public void bussinesMethod(){


No ejb-jar.xml, jboss.xml is needed, just EJB JAR with MyEJB and MyEJBInterface compiled classes.

Now in your client code you need to lookup "MyComponentName".

What does "javax.naming.NoInitialContextException" mean?

Just read the docs:

This exception is thrown when no initial context implementation can be created. The policy of how an initial context implementation is selected is described in the documentation of the InitialContext class.

This exception can be thrown during any interaction with the InitialContext, not only when the InitialContext is constructed. For example, the implementation of the initial context might lazily retrieve the context only when actual methods are invoked on it. The application should not have any dependency on when the existence of an initial context is determined.

But this is explained much better in the docs for InitialContext

How to create JNDI context in Spring Boot with Embedded Tomcat Container

After all i got the answer thanks to wikisona, first the beans:

public TomcatEmbeddedServletContainerFactory tomcatFactory() {
    return new TomcatEmbeddedServletContainerFactory() {

        protected TomcatEmbeddedServletContainer getTomcatEmbeddedServletContainer(
                Tomcat tomcat) {
            return super.getTomcatEmbeddedServletContainer(tomcat);

        protected void postProcessContext(Context context) {
            ContextResource resource = new ContextResource();
            resource.setProperty("driverClassName", "your.db.Driver");
            resource.setProperty("url", "jdbc:yourDb");


public DataSource jndiDataSource() throws IllegalArgumentException, NamingException {
    JndiObjectFactoryBean bean = new JndiObjectFactoryBean();
    return (DataSource)bean.getObject();

the full code it's here:

CSS file not refreshing in browser

The fix is called "hard refresh"

In most Windows and Linux browsers: Hold down Ctrl and press F5.

In Apple Safari: Hold down ? Shift and click the Reload toolbar button.

In Chrome and Firefox for Mac: Hold down both ? Cmd+? Shift and press R.

Intercept a form submit in JavaScript and prevent normal submission

<form onSubmit="return captureForm()"> that should do. Make sure that your captureForm() method returns false.

How to echo out table rows from the db (php)

$result = mysqli_query($conn, $sql); // First parameter is just return of "mysqli_connect()" function
echo "<br>";
echo "<table border='1'>";
while ($row = mysqli_fetch_assoc($result)) { // Important line !!! Check summary get row on array ..
    echo "<tr>";
    foreach ($row as $field => $value) { // I you want you can right this line like this: foreach($row as $value) {
        echo "<td>" . $value . "</td>"; // I just did not use "htmlspecialchars()" function. 
    echo "</tr>";
echo "</table>";

Splitting on last delimiter in Python string?

I just did this for fun

    >>> s = 'a,b,c,d'
    >>> [item[::-1] for item in s[::-1].split(',', 1)][::-1]
    ['a,b,c', 'd']

Caution: Refer to the first comment in below where this answer can go wrong.

VSCode Change Default Terminal

You can also select your default terminal by pressing F1 in VS Code and typing/selecting Terminal: Select Default Shell.

Terminal Selection

Terminal Selection

How do I find which application is using up my port?

How about netstat?

The command is netstat -anob.

(Make sure you run command as admin)

I get:

C:\Windows\system32>netstat -anob

Active Connections

     Proto  Local Address          Foreign Address        State           PID
  TCP                       LISTENING         4
 Can not obtain ownership information

  TCP                LISTENING       692

  TCP                LISTENING       7540

  TCP                LISTENING       4
 Can not obtain ownership information
  TCP                LISTENING       564

  TCP                LISTENING       4480

And If you want to check for the particular port, command to use is: netstat -aon | findstr 8080 from the same path

New line in Sql Query

Pinal Dave explains this well in his blog.

DECLARE @NewLineChar AS CHAR(2) = CHAR(13) + CHAR(10)
PRINT ('SELECT FirstLine AS FL ' + @NewLineChar + 'SELECT SecondLine AS SL')

How to test enum types?

Usually I would say it is overkill, but there are occasionally reasons for writing unit tests for enums.

Sometimes the values assigned to enumeration members must never change or the loading of legacy persisted data will fail. Similarly, apparently unused members must not be deleted. Unit tests can be used to guard against a developer making changes without realising the implications.

Python strip() multiple characters?

strip only strips characters from the very front and back of the string.

To delete a list of characters, you could use the string's translate method:

import string
name = "Barack (of Washington)"
table = string.maketrans( '', '', )
print name.translate(table,"(){}<>")
# Barack of Washington

For..In loops in JavaScript - key value pairs

If you are using Lodash, you can use _.forEach

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key + ": " + value);
// => Logs 'a: 1' then 'b: 2' (iteration order is not guaranteed).

Using Mysql in the command line in osx - command not found?

for me the following commands worked:

$ brew install mysql

$ brew services start mysql

Upper memory limit?

Python can use all memory available to its environment. My simple "memory test" crashes on ActiveState Python 2.6 after using about

1959167 [MiB]

On jython 2.5 it crashes earlier:

 239000 [MiB]

probably I can configure Jython to use more memory (it uses limits from JVM)

Test app:

import sys

sl = []
i = 0
# some magic 1024 - overhead of string object
fill_size = 1024
if sys.version.startswith('2.7'):
    fill_size = 1003
if sys.version.startswith('3'):
    fill_size = 497
MiB = 0
while True:
    s = str(i).zfill(fill_size)
    if i == 0:
            sys.stderr.write('size of one string %d\n' % (sys.getsizeof(s)))
        except AttributeError:
    i += 1
    if i % 1024 == 0:
        MiB += 1
        if MiB % 25 == 0:
            sys.stderr.write('%d [MiB]\n' % (MiB))

In your app you read whole file at once. For such big files you should read the line by line.

C# error: Use of unassigned local variable

The compiler only knows that the code is or isn't reachable if you use "return". Think of Environment.Exit() as a function that you call, and the compiler don't know that it will close the application.

Is there Selected Tab Changed Event in the standard WPF Tab Control

The event generated is bubbling up until it is handled.

This xaml portion below triggers ui_Tab_Changed after ui_A_Changed when the item selected in the ListView changes, regardless of TabItem change in the TabControl.

<TabControl SelectionChanged="ui_Tab_Changed">
    <ListView SelectionChanged="ui_A_Changed" />
    <ListView SelectionChanged="ui_B_Changed" />

We need to consume the event in ui_A_Changed (and ui_B_Changed, and so on):

private void ui_A_Changed(object sender, SelectionChangedEventArgs e) {
  // do what you need to do
  // then consume the event
  e.Handled = true;

Is there any simple way to convert .xls file to .csv file? (Excel)

Install these 2 packages

  <package id="ExcelDataReader" version="3.3.0" targetFramework="net451" />
  <package id="ExcelDataReader.DataSet" version="3.3.0" targetFramework="net451" />

Helper function

using ExcelDataReader;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ExcelToCsv
    public class ExcelFileHelper
        public static bool SaveAsCsv(string excelFilePath, string destinationCsvFilePath)

            using (var stream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                IExcelDataReader reader = null;
                if (excelFilePath.EndsWith(".xls"))
                    reader = ExcelReaderFactory.CreateBinaryReader(stream);
                else if (excelFilePath.EndsWith(".xlsx"))
                    reader = ExcelReaderFactory.CreateOpenXmlReader(stream);

                if (reader == null)
                    return false;

                var ds = reader.AsDataSet(new ExcelDataSetConfiguration()
                    ConfigureDataTable = (tableReader) => new ExcelDataTableConfiguration()
                        UseHeaderRow = false

                var csvContent = string.Empty;
                int row_no = 0;
                while (row_no < ds.Tables[0].Rows.Count)
                    var arr = new List<string>();
                    for (int i = 0; i < ds.Tables[0].Columns.Count; i++)
                    csvContent += string.Join(",", arr) + "\n";
                StreamWriter csv = new StreamWriter(destinationCsvFilePath, false);
                return true;

Usage :

var excelFilePath = Console.ReadLine();
string output = Path.ChangeExtension(excelFilePath, ".csv");
ExcelFileHelper.SaveAsCsv(excelFilePath, output);

Angular 2 Show and Hide an element

We can do it by using the below code snippet..

Angular Code:

 export class AppComponent {  
    toggleShowHide: string = "visible";  

HTML Template:

  Enter text to hide or show item in bellow: 
  <input type="text" [(ngModel)]="toggleShowHide">
  Toggle Show/hide:
  <div [style.visibility]="toggleShowHide">   
     Final Release Angular 2!

count number of rows in a data frame in R based on group

Here is another way of using aggregate to count rows by group: <- read.table(text = '
    month.year    my.cov
      Jan.2000     apple
      Jan.2000      pear
      Jan.2000     peach
      Jan.2001     apple
      Jan.2001     peach
      Feb.2002      pear
', header = TRUE, stringsAsFactors = FALSE, na.strings = NA)  <- aggregate(rep(1, length($month.year)),
                             by=list($month.year), sum)

#    Group.1 x
# 1 Feb.2002 1
# 2 Jan.2000 3
# 3 Jan.2001 2

Convert HH:MM:SS string to seconds only in javascript

This function works for MM:SS as well:

const convertTime = (hms) => {_x000D_
        if (hms.length <3){_x000D_
         return hms_x000D_
        } else if (hms.length <6){_x000D_
          const a = hms.split(':')_x000D_
          return hms = (+a[0]) * 60 + (+a[1])_x000D_
        } else {_x000D_
          const a = hms.split(':')_x000D_
          return hms = (+a[0]) * 60 * 60 + (+a[1]) * 60 + (+a[2])_x000D_

how to convert Lower case letters to upper case letters & and upper case letters to lower case letters

//This is to convert a letter from upper case to lower case
import java.util.Scanner;
    public class ChangeCase {
        public static void main(String[]args) {

            String input;
            Scanner sc= new Scanner(;
                System.out.println("Enter Letter from upper case");

            String result;
            result= input.toLowerCase();

ERROR 1396 (HY000): Operation CREATE USER failed for 'jack'@'localhost'

This post MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES) is useful. Sometimes, there is an anonymous user ''@'localhost' or ''@''. So, to solve the problem,

  1. first drop the user whose 'create user' failed.

  2. Create new user.

  3. Grant required privileges to the new user.

  4. Flush privileges.

Error importing SQL dump into MySQL: Unknown database / Can't create database

If you create your database in direct admin or cpanel, you must edit your sql with notepad or notepad++ and change CREATE DATABASE command to CREATE DATABASE IF NOT EXISTS in line22

Mongoose, update values in array of objects

I had similar issues. Here is the cleanest way to do it.

    const personQuery = {
       _id: 1  

    const itemID = 2;

    Person.findOne(personQuery).then(item => {
       const audioIndex = =>;
       item.items[audioIndex].name = 'Name value';;

Android Transparent TextView?

<TextView android:alpha="0.3" ..., for example.

Scanner is skipping nextLine() after using next() or nextFoo()?

Use this code it will fix your problem.

System.out.println("Enter numerical value");    
int option;
option = input.nextInt(); // Read numerical value from input
System.out.println("Enter 1st string"); 
String string1 = input.nextLine(); // Read 1st string (this is skipped)
System.out.println("Enter 2nd string");
String string2 = input.nextLine(); // Read 2nd string (this appears right after reading numerical value)

Accidentally committed .idea directory files into git

You can remove it from the repo and commit the change.

git rm .idea/ -r --cached
git add -u .idea/
git commit -m "Removed the .idea folder"

After that, you can push it to the remote and every checkout/clone after that will be ok.

Order a MySQL table by two columns

Default sorting is ascending, you need to add the keyword DESC to both your orders:

ORDER BY article_rating DESC, article_time DESC

How can I extract audio from video with ffmpeg?

Here's what I just used:

ffmpeg -i my.mkv -map 0:3 -vn -b:a 320k my.mp3

Options explanation:

  • my.mkv is a source video file, you can use other formats as well
  • -map 0:3 means I want 3rd stream from video file. Put your N there - video files often has multiple audio streams; you can omit it or use -map 0:a to take the default audio stream. Run ffprobe my.mkv to see what streams does the video file have.
  • my.mp3 is a target audio filename, and ffmpeg figures out I want an MP3 from its extension. In my case the source audio stream is ac3 DTS and just copying wasn't what I wanted
  • 320k is a desired target bitrate
  • -vn means I don't want video in target file

SQL Server Management Studio, how to get execution time down to milliseconds

Turn on Client Statistics by doing one of the following:

  • Menu: Query > Include client Statistics
  • Toolbar: Click the button (next to Include Actual Execution Time)
  • Keyboard: Shift-Alt-S

Then you get a new tab which records the timings, IO data and rowcounts etc for (up to) the last 10 exections (plus averages!):

enter image description here

In C++, what is a virtual base class?

About the memory layout

As a side note, the problem with the Dreaded Diamond is that the base class is present multiple times. So with regular inheritance, you believe you have:

 / \
B   C
 \ /

But in the memory layout, you have:

A   A
|   |
B   C
 \ /

This explain why when call D::foo(), you have an ambiguity problem. But the real problem comes when you want to use a member variable of A. For example, let's say we have:

class A
    public :
       foo() ;
       int m_iValue ;
} ;

When you'll try to access m_iValue from D, the compiler will protest, because in the hierarchy, it'll see two m_iValue, not one. And if you modify one, say, B::m_iValue (that is the A::m_iValue parent of B), C::m_iValue won't be modified (that is the A::m_iValue parent of C).

This is where virtual inheritance comes handy, as with it, you'll get back to a true diamond layout, with not only one foo() method only, but also one and only one m_iValue.

What could go wrong?


  • A has some basic feature.
  • B adds to it some kind of cool array of data (for example)
  • C adds to it some cool feature like an observer pattern (for example, on m_iValue).
  • D inherits from B and C, and thus from A.

With normal inheritance, modifying m_iValue from D is ambiguous and this must be resolved. Even if it is, there are two m_iValues inside D, so you'd better remember that and update the two at the same time.

With virtual inheritance, modifying m_iValue from D is ok... But... Let's say that you have D. Through its C interface, you attached an observer. And through its B interface, you update the cool array, which has the side effect of directly changing m_iValue...

As the change of m_iValue is done directly (without using a virtual accessor method), the observer "listening" through C won't be called, because the code implementing the listening is in C, and B doesn't know about it...


If you're having a diamond in your hierarchy, it means that you have 95% probability to have done something wrong with said hierarchy.

How do you easily horizontally center a <div> using CSS?

you can use margin: 0 auto on your css instead of margin-left: auto; margin-right: auto;

How can I plot with 2 different y-axes?

I too suggests, twoord.stackplot() in the plotrix package plots with more of two ordinate axes.

"e0AL fxAL e0CO fxCO e0BR fxBR anos
 51.8  5.9 50.6  6.8 51.0  6.2 1955
 54.7  5.9 55.2  6.8 53.5  6.2 1960
 57.1  6.0 57.9  6.8 55.9  6.2 1965
 59.1  5.6 60.1  6.2 57.9  5.4 1970
 61.2  5.1 61.8  5.0 59.8  4.7 1975
 63.4  4.5 64.0  4.3 61.8  4.3 1980
 65.4  3.9 66.9  3.7 63.5  3.8 1985
 67.3  3.4 68.0  3.2 65.5  3.1 1990
 69.1  3.0 68.7  3.0 67.5  2.6 1995
 70.9  2.8 70.3  2.8 69.5  2.5 2000
 72.4  2.5 71.7  2.6 71.1  2.3 2005
 73.3  2.3 72.9  2.5 72.1  1.9 2010
 74.3  2.2 73.8  2.4 73.2  1.8 2015
 75.2  2.0 74.6  2.3 74.2  1.7 2020
 76.0  2.0 75.4  2.2 75.2  1.6 2025
 76.8  1.9 76.2  2.1 76.1  1.6 2030
 77.6  1.9 76.9  2.1 77.1  1.6 2035
 78.4  1.9 77.6  2.0 77.9  1.7 2040
 79.1  1.8 78.3  1.9 78.7  1.7 2045
 79.8  1.8 79.0  1.9 79.5  1.7 2050
 80.5  1.8 79.7  1.9 80.3  1.7 2055
 81.1  1.8 80.3  1.8 80.9  1.8 2060
 81.7  1.8 80.9  1.8 81.6  1.8 2065
 82.3  1.8 81.4  1.8 82.2  1.8 2070
 82.8  1.8 82.0  1.7 82.8  1.8 2075
 83.3  1.8 82.5  1.7 83.4  1.9 2080
 83.8  1.8 83.0  1.7 83.9  1.9 2085
 84.3  1.9 83.5  1.8 84.4  1.9 2090
 84.7  1.9 83.9  1.8 84.9  1.9 2095
 85.1  1.9 84.3  1.8 85.4  1.9 2100", header=T)

twoord.stackplot(lx=data$anos, rx=data$anos, 
                 ldata=cbind(data$e0AL, data$e0BR, data$e0CO),
                 rdata=cbind(data$fxAL, data$fxBR, data$fxCO),
                 lcol=c("black","red", "blue"),
                 rcol=c("black","red", "blue"), 
                 lylab="Años de Vida", rylab="Hijos x Mujer", 
legend("bottomright", c(paste("Proy:", 
                      c("A. Latina", "Brasil", "Colombia"))), cex=1,
        col=c("black","red", "blue"), lwd=2, bty="n",  
        lty=c(1,1,2), pch=c(NA,1,1) )

Select count(*) from multiple tables

My experience is with SQL Server, but could you do:

select (select count(*) from table1) as count1,
  (select count(*) from table2) as count2

In SQL Server I get the result you are after.

How to do multiple conditions for single If statement

Use the 'And' keyword for a logical and. Like this:

If Not ((filename = testFileName) And (fileName <> "")) Then

How to send a pdf file directly to the printer using JavaScript?

a function to house the print trigger...

function printTrigger(elementId) {
    var getMyFrame = document.getElementById(elementId);

an button to give the user access...

(an onClick on an a or button or input or whatever you wish)

<input type="button" value="Print" onclick="printTrigger('iFramePdf');" />
an iframe pointing to your PDF...

<iframe id="iFramePdf" src="myPdfUrl.pdf" style="dispaly:none;"></iframe>

More :

PHP split alternative?

split is deprecated since it is part of the family of functions which make use of POSIX regular expressions; that entire family is deprecated in favour of the PCRE (preg_*) functions.

If you do not need the regular expression functionality, then explode is a very good choice (and would have been recommended over split even if that were not deprecated), if on the other hand you do need to use regular expressions then the PCRE alternate is simply preg_split.

Could not find or load main class

Check you class name first. It should be p1 as per your batch file instruction. And then check you package of that class, if it is inside any package, specify when you run.

If package is x.y

java x.y.p1

What does "hashable" mean in Python?

Let me give you a working example to understand the hashable objects in python. I am taking 2 Tuples for this example.Each value in a tuple has a unique Hash Value which never changes during its lifetime. So based on this has value, the comparison between two tuples is done. We can get the hash value of a tuple element using the Id().

Comparison between 2 tuplesEquivalence between 2 tuples

Installing PDO driver on MySQL Linux server

  1. PDO stands for PHP Data Object.
  2. PDO_MYSQL is the driver that will implement the interface between the dataobject(database) and the user input (a layer under the user interface called "code behind") accessing your data object, the MySQL database.

The purpose of using this is to implement an additional layer of security between the user interface and the database. By using this layer, data can be normalized before being inserted into your data structure. (Capitals are Capitals, no leading or trailing spaces, all dates at properly formed.)

But there are a few nuances to this which you might not be aware of.

First of all, up until now, you've probably written all your queries in something similar to the URL, and you pass the parameters using the URL itself. Using the PDO, all of this is done under the user interface level. User interface hands off the ball to the PDO which carries it down field and plants it into the database for a 7-point TOUCHDOWN.. he gets seven points, because he got it there and did so much more securely than passing information through the URL.

You can also harden your site to SQL injection by using a data-layer. By using this intermediary layer that is the ONLY 'player' who talks to the database itself, I'm sure you can see how this could be much more secure. Interface to datalayer to database, datalayer to database to datalayer to interface.


By implementing best practices while writing your code you will be much happier with the outcome.

Additional sources:

Re: MySQL Functions in the url php dot net/manual/en/ref dot pdo-mysql dot php

Re: three-tier architecture - adding security to your applications

Re: Object Oriented Design using UML If you really want to learn more about this, this is the best book on the market, Grady Booch was the father of UML

Or check with bitmonkey. There's a group there I'm sure you could learn a lot with.


If we knew what the terminology really meant we wouldn't need to learn anything.


How to set the allowed url length for a nginx request (error code: 414, uri too large)

For anyone having issues with this on, I managed to get this to work using a compilation of SO answers;

You will need the sudo password.

sudo nano /etc/nginx/conf.d/uploads.conf

Replace contents with the following;

fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k;

client_max_body_size 24M;
client_body_buffer_size 128k;

client_header_buffer_size 5120k;
large_client_header_buffers 16 5120k;

how to run a winform from console application?

It´s very simple to do:

Just add following attribute and code to your Main-method:

void Main(string[] args])
   //Do some stuff...
       Application.DoEvents(); //Now if you call "form.Show()" your form won´t be frozen
       //Do your stuff

Now you´re fully able to show WinForms :)

querying WHERE condition to character length?

Sorry, I wasn't sure which SQL platform you're talking about:


$query = ("SELECT * FROM $db WHERE conditions AND LENGTH(col_name) = 3");


$query = ("SELECT * FROM $db WHERE conditions AND LEN(col_name) = 3");

The LENGTH() (MySQL) or LEN() (MSSQL) function will return the length of a string in a column that you can use as a condition in your WHERE clause.


I know this is really old but thought I'd expand my answer because, as Paulo Bueno rightly pointed out, you're most likely wanting the number of characters as opposed to the number of bytes. Thanks Paulo.

So, for MySQL there's the CHAR_LENGTH(). The following example highlights the difference between LENGTH() an CHAR_LENGTH():

    word VARCHAR(100)
) ENGINE INNODB DEFAULT CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci;

INSERT INTO words(word) VALUES('??'), ('happy'), ('hayir');

SELECT word, LENGTH(word) as num_bytes, CHAR_LENGTH(word) AS num_characters FROM words;

| word   | num_bytes | num_characters |
| ??    |         6 |              2 |
| happy  |         5 |              5 |
| hayir  |         6 |              5 |

Be careful if you're dealing with multi-byte characters.

int *array = new int[n]; what is this function actually doing?

new allocates an amount of memory needed to store the object/array that you request. In this case n numbers of int.

The pointer will then store the address to this block of memory.

But be careful, this allocated block of memory will not be freed until you tell it so by writing

delete [] array;

Convert list or numpy array of single element to float in python

Just access the first item of the list/array, using the index access and the index 0:

>>> list_ = [4]
>>> list_[0]
>>> array_ = np.array([4])
>>> array_[0]

This will be an int since that was what you inserted in the first place. If you need it to be a float for some reason, you can call float() on it then:

>>> float(list_[0])

How should I unit test multithreaded code?

Testing MT code for correctness is, as already stated, quite a hard problem. In the end it boils down to ensuring that there are no incorrectly synchronised data races in your code. The problem with this is that there are infinitely many possibilities of thread execution (interleavings) over which you do not have much control (be sure to read this article, though). In simple scenarios it might be possible to actually prove correctness by reasoning but this is usually not the case. Especially if you want to avoid/minimize synchronization and not go for the most obvious/easiest synchronization option.

An approach that I follow is to write highly concurrent test code in order to make potentially undetected data races likely to occur. And then I run those tests for some time :) I once stumbled upon a talk where some computer scientist where showing off a tool that kind of does this (randomly devising test from specs and then running them wildly, concurrently, checking for the defined invariants to be broken).

By the way, I think this aspect of testing MT code has not been mentioned here: identify invariants of the code that you can check for randomly. Unfortunately, finding those invariants is quite a hard problem, too. Also they might not hold all the time during execution, so you have to find/enforce executions points where you can expect them to be true. Bringing the code execution to such a state is also a hard problem (and might itself incur concurrency issues. Whew, it's damn hard!

Some interesting links to read:

php how to go one level up on dirname(__FILE__)

You could use PHP's dirname function. <?php echo dirname(__DIR__); ?>. That will give you the name of the parent directory of __DIR__, which stores the current directory.

The role of #ifdef and #ifndef

The code looks strange because the printf are not in any function blocks.

SELECT only rows that contain only alphanumeric characters in MySQL

Try this code:

SELECT * FROM table WHERE column REGEXP '^[A-Za-z0-9]+$'

This makes sure that all characters match.

What are some good SSH Servers for windows?

I've been using Bitvise SSH Server for a number of years. It is a wonderful product and it is easy to setup and maintain. It gives you great control over how users connect to the server with support for security groups.

How to determine a user's IP address in node

If you get multiple IPs , this works for me:

var ipaddress = (req.headers['x-forwarded-for'] || _x000D_
req.connection.remoteAddress || _x000D_
req.socket.remoteAddress || _x000D_

PostgreSQL - SQL state: 42601 syntax error

Your function would work like this:

CREATE OR REPLACE FUNCTION prc_tst_bulk(sql text)
RETURNS TABLE (name text, rowcount integer) AS 

WITH v_tb_person AS (' || sql || $x$)
SELECT name, count(*)::int FROM v_tb_person WHERE nome LIKE '%a%' GROUP BY name
SELECT name, count(*)::int FROM v_tb_person WHERE gender = 1 GROUP BY name$x$;

$$ LANGUAGE plpgsql;


SELECT * FROM prc_tst_bulk($$SELECT a AS name, b AS nome, c AS gender FROM tbl$$)
  • You cannot mix plain and dynamic SQL the way you tried to do it. The whole statement is either all dynamic or all plain SQL. So I am building one dynamic statement to make this work. You may be interested in the chapter about executing dynamic commands in the manual.

  • The aggregate function count() returns bigint, but you had rowcount defined as integer, so you need an explicit cast ::int to make this work

  • I use dollar quoting to avoid quoting hell.

However, is this supposed to be a honeypot for SQL injection attacks or are you seriously going to use it? For your very private and secure use, it might be ok-ish - though I wouldn't even trust myself with a function like that. If there is any possible access for untrusted users, such a function is a loaded footgun. It's impossible to make this secure.

Craig (a sworn enemy of SQL injection!) might get a light stroke, when he sees what you forged from his piece of code in the answer to your preceding question. :)

The query itself seems rather odd, btw. But that's beside the point here.

HTML tag <a> want to add both href and onclick working

Use jQuery. You need to capture the click event and then go on to the website.

$("#myHref").on('click', function() {_x000D_
  alert("inside onclick");_x000D_
  window.location = "";_x000D_
<script src=""></script>_x000D_
<a href="#" id="myHref">Click me</a>

Form Validation With Bootstrap (jQuery)

Check this library, it's completable with booth bootstrap 3 and bootstrap 4


    <div class="form-group">
        <input class="form-control" data-validator="required|min:4|max:10">


$(document).on('blur', '[data-validator]', function () {
    new Validator($(this));

What are the differences in die() and exit() in PHP?

From what I know when I look at this question here

It said there that "in PHP, there is a distinct difference in Header output. In the examples below I chose to use a different header but for sake of showing the difference between exit() and die() that doesn't matter", and tested (personally)

Google Play Services GCM 9.2.0 asks to "update" back to 9.0.0

Just put this line at the bottom of your app-module's (not project root's) gradle file.

apply plugin: ''

Then rebuild your project.

How would I find the second largest salary from the employee table?

   select * from compensation where Salary = (
      select top 1 Salary from (
      select top 2 Salary from compensation 
      group by Salary order by Salary desc) top2
      order by Salary)

which will give you all rows with second highest salary, which a few people may share

Ignore cells on Excel line graph

Not for blanks in the middle of a range, but this works for a complex chart from a start date until infinity (ie no need to adjust the chart's data source each time informatiom is added), without showing any lines for dates that have not yet been entered. As you add dates and data to the spreadsheet, the chart expands. Without it, the chart has a brain hemorrhage.

So, to count a complex range of conditions over an extended period of time but only if the date of the events is not blank :

=IF($B6<>"",(COUNTIF($O6:$O6,Q$5)),"") returns “#N/A” if there is no date in column B.

In other words, "count apples or oranges or whatever in column O (as determined by what is in Q5) but only if column B (the dates) is not blank". By returning “#N/A”, the chart will skip the "blank" rows (blank as in a zero value or rather "#N/A").

From that table of returned values you can make a chart from a date in the past to infinity

Moment JS start and end of given month

your startDate is first-day-of-month, In this case we can use

var endDate = moment(startDate).add(1, 'months').subtract(1, 'days');

Hope this helps!!

How to set text size in a button in html

Try this, its working in FF

button {
 font-family: Arial,Helvetica,sans-serif;
 font-size: 14px;

How to check if a python module exists without importing it

You can also use importlib directly

import importlib

except ImportError:
    # Handle error

How to measure elapsed time in Python?

Use profiler module. It gives a very detailed profile.

import profile'main()')

it outputs something like:

          5 function calls in 0.047 seconds

   Ordered by: standard name

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
        1    0.000    0.000    0.000    0.000 :0(exec)
        1    0.047    0.047    0.047    0.047 :0(setprofile)
        1    0.000    0.000    0.000    0.000 <string>:1(<module>)
        0    0.000             0.000          profile:0(profiler)
        1    0.000    0.000    0.047    0.047 profile:0(main())
        1    0.000    0.000    0.000    0.000

I've found it very informative.

Min and max value of input in angular4 application

I succeeded by using a form control. This is my html code :

    <input type="number" min="0" max="100" required mdInput placeholder="Charge" [(ngModel)]="rateInput" name="rateInput" [formControl]="rateControl">
    <md-error>Please enter a value between 0 and 100</md-error>

And in my Typescript code, I have :

this.rateControl = new FormControl("", [Validators.max(100), Validators.min(0)])

So, if we enter a value higher than 100 or smaller than 0, the material design input become red and the field is not validate. So after, if the value is not good, I don't save when I click on the save button.

Error while waiting for device: Time out after 300seconds waiting for emulator to come online

I had the same problem. I'm using Android Studio 2.3 and Debian 9.1 Stretch 64 bits. In my case, the problem was in default settings established in graphics aceleration configuration. To solve the problem I opened the AVD Manager, then I selected the device and I opened config file (config.ini) selecting "Show on disk" option whitin "Actions" column. Within the file, I changed the value setted in hw.gpu.mode variable from mesa to swiftshader. After saved the changes, the emulator started without any problems. More options availables could be found on this link.

How do I display an alert dialog on Android?

Use AlertDialog.Builder :

AlertDialog alertDialog = new AlertDialog.Builder(this)
//set icon 
//set title
.setTitle("Are you sure to Exit")
//set message
.setMessage("Exiting will call finish() method")
//set positive button
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialogInterface, int i) {
   //set what would happen when positive button is clicked    
//set negative button
.setNegativeButton("No", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialogInterface, int i) {
   //set what should happen when negative button is clicked
        Toast.makeText(getApplicationContext(),"Nothing Happened",Toast.LENGTH_LONG).show();

You will get the following output.

android alert dialog

To view alert dialog tutorial use the link below.

Android Alert Dialog Tutorial

How do I make text bold in HTML?

HTML doesn't have a <bold> tag, instead you would have to use <b>. Note however, that using <b> is discouraged in favor of CSS for a while now. You would be better off using CSS to achieve that.

The <strong> tag is a semantic element for strong emphasis which defaults to bold.

CSS3 Transparency + Gradient

Yes. You can use rgba in both webkit and moz gradient declarations:

/* webkit example */
background-image: -webkit-gradient(
  linear, left top, left bottom, from(rgba(50,50,50,0.8)),
  to(rgba(80,80,80,0.2)), color-stop(.5,#333333)


/* mozilla example - FF3.6+ */
background-image: -moz-linear-gradient(
  rgba(255, 255, 255, 0.7) 0%, rgba(255, 255, 255, 0) 95%


Apparently you can even do this in IE, using an odd "extended hex" syntax. The first pair (in the example 55) refers to the level of opacity:

/* approximately a 33% opacity on blue */
filter: progid:DXImageTransform.Microsoft.gradient(
  startColorstr=#550000FF, endColorstr=#550000FF

/* IE8 uses -ms-filter for whatever reason... */
-ms-filter: progid:DXImageTransform.Microsoft.gradient(
  startColorstr=#550000FF, endColorstr=#550000FF


C: scanf to array


scanf("%d", &array[0]);

and use == for comparision instead of =

C# using Sendkey function to send a key to another application

If notepad is already started, you should write:

// import the function in your class
[DllImport ("User32.dll")]
static extern int SetForegroundWindow(IntPtr point);


Process p = Process.GetProcessesByName("notepad").FirstOrDefault();
if (p != null)
    IntPtr h = p.MainWindowHandle;

GetProcessesByName returns an array of processes, so you should get the first one (or find the one you want).

If you want to start notepad and send the key, you should write:

Process p = Process.Start("notepad.exe");
IntPtr h = p.MainWindowHandle;

The only situation in which the code may not work is when notepad is started as Administrator and your application is not.

Exact difference between CharSequence and String in java

From the Java API of CharSequence:

A CharSequence is a readable sequence of characters. This interface provides uniform, read-only access to many different kinds of character sequences.

This interface is then used by String, CharBuffer and StringBuffer to keep consistency for all method names.

How can I get zoom functionality for images?

Adding to @Mike's answer. I also needed double tap to restore the image to the original dimensions when first viewed. So I added a whole heap of "orig..." instance variables and added the SimpleOnGestureListener which did the trick.

import android.content.Context;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

    Matrix matrix = new Matrix();

    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // Remember some things for zooming
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;

    float redundantXSpace, redundantYSpace, origRedundantXSpace, origRedundantYSpace;;

    float width, height;
    static final int CLICK = 3;
    static final float SAVE_SCALE = 1f;
    float saveScale = SAVE_SCALE;

    float right, bottom, origWidth, origHeight, bmWidth, bmHeight, origScale, origBottom,origRight;

    ScaleGestureDetector mScaleDetector;
    GestureDetector mGestureDetector;

    Context context;

    public TouchImageView(Context context) {
        this.context = context;
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());

        matrix.setTranslate(1f, 1f);
        m = new float[9];

        setOnTouchListener(new OnTouchListener() {

            public boolean onTouch(View v, MotionEvent event) {

                boolean onDoubleTapEvent = mGestureDetector.onTouchEvent(event);
                if (onDoubleTapEvent) {
                    // Reset Image to original scale values
                    mode = NONE;
                    bottom = origBottom;
                    right = origRight;
                    last = new PointF();
                    start = new PointF();
                    m = new float[9];
                    saveScale = SAVE_SCALE;
                    matrix = new Matrix();
                    matrix.setScale(origScale, origScale);
                    matrix.postTranslate(origRedundantXSpace, origRedundantYSpace);
                    return true;


                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    last.set(event.getX(), event.getY());
                    mode = DRAG;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        float deltaX = curr.x - last.x;
                        float deltaY = curr.y - last.y;
                        float scaleWidth = Math.round(origWidth * saveScale);
                        float scaleHeight = Math.round(origHeight * saveScale);
                        if (scaleWidth < width) {
                            deltaX = 0;
                            if (y + deltaY > 0)
                                deltaY = -y;
                            else if (y + deltaY < -bottom)
                                deltaY = -(y + bottom);
                        } else if (scaleHeight < height) {
                            deltaY = 0;
                            if (x + deltaX > 0)
                                deltaX = -x;
                            else if (x + deltaX < -right)
                                deltaX = -(x + right);
                        } else {
                            if (x + deltaX > 0)
                                deltaX = -x;
                            else if (x + deltaX < -right)
                                deltaX = -(x + right);

                            if (y + deltaY > 0)
                                deltaY = -y;
                            else if (y + deltaY < -bottom)
                                deltaY = -(y + bottom);
                        matrix.postTranslate(deltaX, deltaY);
                        last.set(curr.x, curr.y);

                case MotionEvent.ACTION_UP:
                    mode = NONE;
                    int xDiff = (int) Math.abs(curr.x - start.x);
                    int yDiff = (int) Math.abs(curr.y - start.y);
                    if (xDiff < CLICK && yDiff < CLICK)

                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;


                return true; // indicate event was handled


        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            public boolean onDoubleTapEvent(MotionEvent e) {
                return true;

    public void setImageBitmap(Bitmap bm) {
        bmWidth = bm.getWidth();
        bmHeight = bm.getHeight();

    public void setMaxZoom(float x) {
        maxScale = x;

    private class ScaleListener extends
            ScaleGestureDetector.SimpleOnScaleGestureListener {
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            mode = ZOOM;
            return true;

        public boolean onScale(ScaleGestureDetector detector) {
            float mScaleFactor = (float) Math.min(
                    Math.max(.95f, detector.getScaleFactor()), 1.05);
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale) {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            } else if (saveScale < minScale) {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            right = width * saveScale - width
                    - (2 * redundantXSpace * saveScale);
            bottom = height * saveScale - height
                    - (2 * redundantYSpace * saveScale);
            if (origWidth * saveScale <= width
                    || origHeight * saveScale <= height) {
                matrix.postScale(mScaleFactor, mScaleFactor, width / 2,
                        height / 2);
                if (mScaleFactor < 1) {
                    float x = m[Matrix.MTRANS_X];
                    float y = m[Matrix.MTRANS_Y];
                    if (mScaleFactor < 1) {
                        if (Math.round(origWidth * saveScale) < width) {
                            if (y < -bottom)
                                matrix.postTranslate(0, -(y + bottom));
                            else if (y > 0)
                                matrix.postTranslate(0, -y);
                        } else {
                            if (x < -right)
                                matrix.postTranslate(-(x + right), 0);
                            else if (x > 0)
                                matrix.postTranslate(-x, 0);
            } else {
                matrix.postScale(mScaleFactor, mScaleFactor,
                        detector.getFocusX(), detector.getFocusY());
                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                if (mScaleFactor < 1) {
                    if (x < -right)
                        matrix.postTranslate(-(x + right), 0);
                    else if (x > 0)
                        matrix.postTranslate(-x, 0);
                    if (y < -bottom)
                        matrix.postTranslate(0, -(y + bottom));
                    else if (y > 0)
                        matrix.postTranslate(0, -y);
            return true;


    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        height = MeasureSpec.getSize(heightMeasureSpec);
        // Fit to screen.
        float scale;
        float scaleX = (float) width / (float) bmWidth;
        float scaleY = (float) height / (float) bmHeight;
        scale = Math.min(scaleX, scaleY);
        matrix.setScale(scale, scale);
        saveScale = SAVE_SCALE;
        origScale = scale;

        // Center the image
        redundantYSpace = (float) height - (scale * (float) bmHeight);
        redundantXSpace = (float) width - (scale * (float) bmWidth);
        redundantYSpace /= (float) 2;
        redundantXSpace /= (float) 2;

        origRedundantXSpace = redundantXSpace;
        origRedundantYSpace = redundantYSpace;

        matrix.postTranslate(redundantXSpace, redundantYSpace);

        origWidth = width - 2 * redundantXSpace;
        origHeight = height - 2 * redundantYSpace;
        right = width * saveScale - width - (2 * redundantXSpace * saveScale);
        bottom = height * saveScale - height
                - (2 * redundantYSpace * saveScale);
        origRight = right;
        origBottom = bottom;


Oracle ORA-12154: TNS: Could not resolve service name Error?

If you have a 32bit DSN and a 64bit DSN with same names, Windows will automatically choose the 64bit one and If your application is 32bit it shows this error. Just watch out for that.

Getting the name of a variable as a string

The only objects in Python that have canonical names are modules, functions, and classes, and of course there is no guarantee that this canonical name has any meaning in any namespace after the function or class has been defined or the module imported. These names can also be modified after the objects are created so they may not always be particularly trustworthy.

What you want to do is not possible without recursively walking the tree of named objects; a name is a one-way reference to an object. A common or garden-variety Python object contains no references to its names. Imagine if every integer, every dict, every list, every Boolean needed to maintain a list of strings that represented names that referred to it! It would be an implementation nightmare, with little benefit to the programmer.

SQL Server Pivot Table with multiple column aggregates

I would do this slightly different by applying both the UNPIVOT and the PIVOT functions to get the final result. The unpivot takes the values from both the totalcount and totalamount columns and places them into one column with multiple rows. You can then pivot on those results.:

select chardate,
  Australia_totalcount as [Australia # of Transactions], 
  Australia_totalamount as [Australia Total $ Amount],
  Austria_totalcount as [Austria # of Transactions], 
  Austria_totalamount as [Austria Total $ Amount]
    country +'_'+col col, 
    select numericmonth, 
      cast(totalcount as numeric(10, 2)) totalcount,
      cast(totalamount as numeric(10, 2)) totalamount
    from mytransactions
  ) src
    for col in (totalcount, totalamount)
  ) unpiv
) s
  for col in (Australia_totalcount, Australia_totalamount,
              Austria_totalcount, Austria_totalamount)
) piv
order by numericmonth

See SQL Fiddle with Demo.

If you have an unknown number of country names, then you can use dynamic SQL:

    @colsName AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(country +'_'+c.col) 
                      from mytransactions
                      cross apply 
                        select 'TotalCount' col
                        union all
                        select 'TotalAmount'
                      ) c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 

select @colsName 
    = STUFF((SELECT distinct ', ' + QUOTENAME(country +'_'+c.col) 
               +' as ['
               + country + case when c.col = 'TotalCount' then ' # of Transactions]' else 'Total $ Amount]' end
             from mytransactions
             cross apply 
                select 'TotalCount' col
                union all
                select 'TotalAmount'
             ) c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 

set @query 
  = 'SELECT chardate, ' + @colsName + ' 
        country +''_''+col col, 
        select numericmonth, 
          cast(totalcount as numeric(10, 2)) totalcount,
          cast(totalamount as numeric(10, 2)) totalamount
        from mytransactions
      ) src
        for col in (totalcount, totalamount)
      ) unpiv
     ) s
       for col in (' + @cols + ')
     ) p 
     order by numericmonth'


See SQL Fiddle with Demo

Both give the result:

| Jul-12               |                          36 |                   699.96 |                        11 |                 257.82 |
| Aug-12               |                          44 |                  1368.71 |                         5 |                 126.55 |
| Sep-12               |                          52 |                  1161.33 |                         7 |                  92.11 |
| Oct-12               |                          50 |                  1099.84 |                        12 |                 103.56 |
| Nov-12               |                          38 |                  1078.94 |                        21 |                 377.68 |
| Dec-12               |                          63 |                  1668.23 |                         3 |                  14.35 |

Search and replace part of string in database

I think 2 update calls should do

update VersionedFields
set Value = replace(value,'<iframe','<a><iframe')

update VersionedFields
set Value = replace(value,'> </iframe>','</a>')

Ruby optional parameters

1) You cannot overload the method (Why doesn't ruby support method overloading?) so why not write a new method altogether?

2) I solved a similar problem using the splat operator * for an array of zero or more length. Then, if I want to pass a parameter(s) I can, it is interpreted as an array, but if I want to call the method without any parameter then I don't have to pass anything. See Ruby Programming Language pages 186/187

rotate image with css

Perform rotation using transform: rotate(xdeg) and also apply overflow: hidden to the parent component to avoid overlapping effect

.div-parent {
   overflow: hidden

.div-child {
   transform: rotate(270deg);

How do I move files in node.js?

Using nodejs natively

var fs = require('fs')

var oldPath = 'old/path/file.txt'
var newPath = 'new/path/file.txt'

fs.rename(oldPath, newPath, function (err) {
  if (err) throw err
  console.log('Successfully renamed - AKA moved!')

(NOTE: "This will not work if you are crossing partitions or using a virtual filesystem not supporting moving files. [...]" – Flavien Volken Sep 2 '15 at 12:50")

Reading CSV file and storing values into an array

var firstColumn = new List<string>();
var lastColumn = new List<string>();

// your code for reading CSV file

foreach(var line in file)
    var array = line.Split(';');

var firstArray = firstColumn.ToArray();
var lastArray = lastColumn.ToArray();

UnhandledPromiseRejectionWarning: This error originated either by throwing inside of an async function without a catch block

I resolve the problem. It's very simple . if do you checking care the problem may be because the auxiliar variable has whitespace. Why ? I don't know but yus must use the trim() method and will resolve the problem

Changing MongoDB data store directory

Copy the contents of /var/lib/mongodb to /data/db. The files you should be looking for should have names like your_db_name.ns and your_dbname.n where n is a number starting with 0. If you do not see such files under /var/lib/mongodb, search for them on your filesystem.

Once copied over, use --dbpath=/data/db when starting MongoDB via the mongod command.

How to close a Java Swing application from the code

The following program includes code that will terminate a program lacking extraneous threads without explicitly calling System.exit(). In order to apply this example to applications using threads/listeners/timers/etc, one need only insert cleanup code requesting (and, if applicable, awaiting) their termination before the WindowEvent is manually initiated within actionPerformed().

For those who wish to copy/paste code capable of running exactly as shown, a slightly-ugly but otherwise irrelevant main method is included at the end.

public class CloseExample extends JFrame implements ActionListener {

    private JButton turnOffButton;

    private void addStuff() {
        turnOffButton = new JButton("Exit");

    public void actionPerformed(ActionEvent quitEvent) {
        /* Iterate through and close all timers, threads, etc here */
                new WindowEvent(
                      this, WindowEvent.WINDOW_CLOSING));

    public CloseExample() {
        super("Close Me!");

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                CloseExample cTW = new CloseExample();
                cTW.setSize(200, 100);

ConnectivityManager getNetworkInfo(int) deprecated

It is good to check whether your network is connected to Internet:

fun isNetworkAvailable(context: Context): Boolean {
    try {
        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        return if (Build.VERSION.SDK_INT > 22) {
            val an = cm.activeNetwork ?: return false
            val capabilities = cm.getNetworkCapabilities(an) ?: return false
        } else {
            val a = cm.activeNetworkInfo ?: return false
            a.isConnected && (a.type == ConnectivityManager.TYPE_WIFI || a.type == ConnectivityManager.TYPE_MOBILE)
    } catch (e: Exception) {
    return false

How to retrieve the current value of an oracle sequence without increment it?

select MY_SEQ_NAME.currval from DUAL;

Keep in mind that it only works if you ran select MY_SEQ_NAME.nextval from DUAL; in the current sessions.

Can grep show only words that match search pattern?

You can also try pcregrep. There is also a -w option in grep, but in some cases it doesn't work as expected.

From Wikipedia:

cat fruitlist.txt

grep -w apple fruitlist.txt

Create a folder if it doesn't already exist

Here you go.

if (!is_dir('path/to/directory')) {
    if (!mkdir('path/to/directory', 0777, true) && !is_dir('path/to/directory')) {
        throw new \RuntimeException(sprintf('Directory "%s" was not created', 'path/to/directory'));

How to get first character of string?

Looks like I am late to the party, but try the below solution which I personally found the best solution:

var x = "testing sub string"

Output should show alert with below values: "t" "e"

How to use andWhere and orWhere in Doctrine?

Here's an example for those who have more complicated conditions and using Doctrine 2.* with QueryBuilder:

$qb->where(' = 1')
      $qb->expr()->eq('', 1),
      $qb->expr()->eq('', 2)

Those are expressions mentioned in Czechnology answer.

What is the difference between "px", "dip", "dp" and "sp"?

px - Pixels - point per scale corresponds to actual pixels on the screen.

i - Inches - based on the physical size of the screen.

mm - Millimeters - based on the physical size of the screen.

pt - Points - 1/72 of an inch based on the physical size of the screen.

dp - Density-independent Pixels - an abstract unit that is based on the physical density of the screen. These units are relative to a 160 dpi screen, so one dp is one pixel on a 160 dpi screen. The ratio of dp-to-pixel will change with the screen density, but not necessarily in direct proportion. Note: The compiler accepts both dip and dp, though dp is more consistent with sp.

sp - scalable pixels - this is like the dp unit, but it is also scaled by the user's font size preference. It is recommended that you use this unit when specifying font sizes, so they will be adjusted for both the screen density and user's preference.

Take the example of two screens that are the same size but one has a screen density of 160 dpi (dots per inch, i.e. pixels per inch) and the other is 240 dpi.

                          Lower resolution screen     Higher resolution, same size
Physical Width                      1.5 inches                        1.5 inches
Dots Per Inch (“dpi”)               160                               240
Pixels (=width*dpi)                 240                               360
Density (factor of baseline 160)    1.0                               1.5

Density-independent pixels          240                               240
(“dip” or “dp” or “dps”)

Scale-independent pixels 
 (“sip” or “sp”)                  Depends on user font size settings    same

How to use 'find' to search for files created on a specific date?

You can't. The -c switch tells you when the permissions were last changed, -a tests the most recent access time, and -m tests the modification time. The filesystem used by most flavors of Linux (ext3) doesn't support a "creation time" record. Sorry!

How do I get the directory that a program is running from?

No, there's no standard way. I believe that the C/C++ standards don't even consider the existence of directories (or other file system organizations).

On Windows the GetModuleFileName() will return the full path to the executable file of the current process when the hModule parameter is set to NULL. I can't help with Linux.

Also you should clarify whether you want the current directory or the directory that the program image/executable resides. As it stands your question is a little ambiguous on this point.

Android Studio 3.0 Flavor Dimension Issue

in KotlinDSL you can use like this :

flavorDimensions ("PlaceApp")
productFlavors {
    create("tapsi") {
        buildConfigField("String", "API_BASE_URL", "https://xxx/x/x/")


NodeJS accessing file with relative path

Simple! The folder named .. is the parent folder, so you can make the path to the file you need as such

var foobar = require('../config/dev/foobar.json');

If you needed to go up two levels, you would write ../../ etc

Some more details about this in this SO answer and it's comments

Android - Best and safe way to stop thread

Currently and unfortunately we can't do anything to stop the thread....

Adding something to Matt's answer we can call interrupt() but that doesn't stop thread... Just tells the system to stop the thread when system wants to kill some threads. Rest is done by system, and we can check it by calling interrupted().

[p.s. : If you are really going with interrupt() I would ask you to do some experiments with a short sleep after calling interrupt()]

The module was expected to contain an assembly manifest

First try to open the file with a decompiler such as ILSpy, your dll might be corrupt. I had this error on an online web site, when I downloaded the dll and tried to open it, it was corrupt, probably some error occurred while uploading it via ftp.

GC overhead limit exceeded

From Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning

the following

Excessive GC Time and OutOfMemoryError

The concurrent collector will throw an OutOfMemoryError if too much time is being spent in garbage collection: if more than 98% of the total time is spent in garbage collection and less than 2% of the heap is recovered, an OutOfMemoryError will be thrown. This feature is designed to prevent applications from running for an extended period of time while making little or no progress because the heap is too small. If necessary, this feature can be disabled by adding the option -XX:-UseGCOverheadLimit to the command line.

The policy is the same as that in the parallel collector, except that time spent performing concurrent collections is not counted toward the 98% time limit. In other words, only collections performed while the application is stopped count toward excessive GC time. Such collections are typically due to a concurrent mode failure or an explicit collection request (e.g., a call to System.gc()).

in conjunction with a passage further down

One of the most commonly encountered uses of explicit garbage collection occurs with RMIs distributed garbage collection (DGC). Applications using RMI refer to objects in other virtual machines. Garbage cannot be collected in these distributed applications without occasionally collection the local heap, so RMI forces full collections periodically. The frequency of these collections can be controlled with properties. For example,

java -Dsun.rmi.dgc.client.gcInterval=3600000

-Dsun.rmi.dgc.server.gcInterval=3600000 specifies explicit collection once per hour instead of the default rate of once per minute. However, this may also cause some objects to take much longer to be reclaimed. These properties can be set as high as Long.MAX_VALUE to make the time between explicit collections effectively infinite, if there is no desire for an upper bound on the timeliness of DGC activity.

Seems to imply that the evaluation period for determining the 98% is one minute long, but it might be configurable on Sun's JVM with the correct define.

Of course, other interpretations are possible.

Convert audio files to mp3 using ffmpeg

Never mind,

I am converting my audio files to mp2 by using the command:

ffmpeg -i input.wav -f mp2 output.mp3

This command works perfectly.

I know that this actually converts the files to mp2 format, but then the resulting file sizes are the same..

How to convert rdd object to dataframe in spark

This code works perfectly from Spark 2.x with Scala 2.11

Import necessary classes

import org.apache.spark.sql.{Row, SparkSession}
import org.apache.spark.sql.types.{DoubleType, StringType, StructField, StructType}

Create SparkSession Object, and Here it's spark

val spark: SparkSession = SparkSession.builder.master("local").getOrCreate
val sc = spark.sparkContext // Just used to create test RDDs

Let's an RDD to make it DataFrame

val rdd = sc.parallelize(
    ("first", Array(2.0, 1.0, 2.1, 5.4)),
    ("test", Array(1.5, 0.5, 0.9, 3.7)),
    ("choose", Array(8.0, 2.9, 9.1, 2.5))

Method 1

Using SparkSession.createDataFrame(RDD obj).

val dfWithoutSchema = spark.createDataFrame(rdd)
|    _1|                  _2|
| first|[2.0, 1.0, 2.1, 5.4]|
|  test|[1.5, 0.5, 0.9, 3.7]|
|choose|[8.0, 2.9, 9.1, 2.5]|

Method 2

Using SparkSession.createDataFrame(RDD obj) and specifying column names.

val dfWithSchema = spark.createDataFrame(rdd).toDF("id", "vals")
|    id|                vals|
| first|[2.0, 1.0, 2.1, 5.4]|
|  test|[1.5, 0.5, 0.9, 3.7]|
|choose|[8.0, 2.9, 9.1, 2.5]|

Method 3 (Actual answer to the question)

This way requires the input rdd should be of type RDD[Row].

val rowsRdd: RDD[Row] = sc.parallelize(
    Row("first", 2.0, 7.0),
    Row("second", 3.5, 2.5),
    Row("third", 7.0, 5.9)

create the schema

val schema = new StructType()
  .add(StructField("id", StringType, true))
  .add(StructField("val1", DoubleType, true))
  .add(StructField("val2", DoubleType, true))

Now apply both rowsRdd and schema to createDataFrame()

val df = spark.createDataFrame(rowsRdd, schema)
|    id|val1|val2|
| first| 2.0| 7.0|
|second| 3.5| 2.5|
| third| 7.0| 5.9|

How to count the number of set bits in a 32-bit integer?

if you're using C++ another option is to use template metaprogramming:

// recursive template to sum bits in an int
template <int BITS>
int countBits(int val) {
        // return the least significant bit plus the result of calling ourselves with
        // .. the shifted value
        return (val & 0x1) + countBits<BITS-1>(val >> 1);

// template specialisation to terminate the recursion when there's only one bit left
int countBits<1>(int val) {
        return val & 0x1;

usage would be:

// to count bits in a byte/char (this returns 8)
countBits<8>( 255 )

// another byte (this returns 7)
countBits<8>( 254 )

// counting bits in a word/short (this returns 1)
countBits<16>( 256 )

you could of course further expand this template to use different types (even auto-detecting bit size) but I've kept it simple for clarity.

edit: forgot to mention this is good because it should work in any C++ compiler and it basically just unrolls your loop for you if a constant value is used for the bit count (in other words, I'm pretty sure it's the fastest general method you'll find)

How to retrieve the hash for the current commit in Git?

To turn arbitrary extended object reference into SHA-1, use simply git-rev-parse, for example

git rev-parse HEAD


git rev-parse --verify HEAD

You can also retrieve the short version like this

git rev-parse --short HEAD

Sidenote: If you want to turn references (branches and tags) into SHA-1, there is git show-ref and git for-each-ref.

GDB: Listing all mapped memory regions for a crashed process

You can also use info files to list all the sections of all the binaries loaded in process binary.

How get permission for camera in android.(Specifically Marshmallow)

This works for me, the source is here

// Here, this is the current activity
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED)
     if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA))

          ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA );
          // app-defined int constant. The callback method gets the
          // result of the request.

Breaking out of nested loops

If you're able to extract the loop code into a function, a return statement can be used to exit the outermost loop at any time.

def foo():
    for x in range(10):
        for y in range(10):
            if x*y > 50:

If it's hard to extract that function you could use an inner function, as @bjd2385 suggests, e.g.

def your_outer_func():
    def inner_func():
        for x in range(10):
            for y in range(10):
                if x*y > 50:

Best way to randomize an array with .NET

You don't need complicated algorithms.

Just one simple line:

Random random = new Random();
array.ToList().Sort((x, y) => random.Next(-1, 1)).ToArray();

Note that we need to convert the Array to a List first, if you don't use List in the first place.

Also, mind that this is not efficient for very large arrays! Otherwise it's clean & simple.

Python conversion between coordinates

Using numpy, you can define the following:

import numpy as np

def cart2pol(x, y):
    rho = np.sqrt(x**2 + y**2)
    phi = np.arctan2(y, x)
    return(rho, phi)

def pol2cart(rho, phi):
    x = rho * np.cos(phi)
    y = rho * np.sin(phi)
    return(x, y)

how to evenly distribute elements in a div next to each other?

Make all spans used inline-block elements. Create an empty stretch span with a 100% width beneath the list of spans containing the menu items. Next make the div containing the spans text-align: justified. This would then force the inline-block elements [your menu items] to evenly distribute.

  <div id="container">

          <div class="social">
            <a href="#" target="_blank" aria-label="facebook-link">
            <img src="">
            <a href="#" target="_blank" aria-label="twitter-link">
                <img src="">
            <a href="#" target="_blank" aria-label="youtube-link">
                <img src="">
            <a href="#" target="_blank" aria-label="pinterest-link">
                 <img src="">
            <a href="#" target="_blank" aria-label="snapchat-link">
                <img src="">
            <a href="#" target="_blank" aria-label="blog-link">
                 <img src="">

            <a href="#" aria-label="phone-link">
                 <img src="">
            <span class="stretch"></span>

How can I SELECT multiple columns within a CASE WHEN on SQL Server?

"Case" can return single value only, but you can use complex type:

create type foo as (a int, b text);
select (case 1 when 1 then (1,'qq')::foo else (2,'ww')::foo end).*;

Android Button setOnClickListener Design

If you're targeting 1.6 or later, you can use the android:onClick xml attribute to remove some of the repetitive code. See this blog post by Romain Guy.

   android:onClick="myClickHandler" />

And in the Java class, use these below lines of code:

class MyActivity extends Activity {
    public void myClickHandler(View target) {
        // Do stuff

Count number of 1's in binary representation

I saw the following solution from another website:

int count_one(int x){
    x = (x & (0x55555555)) + ((x >> 1) & (0x55555555));
    x = (x & (0x33333333)) + ((x >> 2) & (0x33333333));
    x = (x & (0x0f0f0f0f)) + ((x >> 4) & (0x0f0f0f0f));
    x = (x & (0x00ff00ff)) + ((x >> 8) & (0x00ff00ff));
    x = (x & (0x0000ffff)) + ((x >> 16) & (0x0000ffff));
    return x;

How to change the docker image installation directory?

With recent versions of Docker, you would set the value of the data-root parameter to your custom path, in /etc/docker/daemon.json (according to

With older versions, you can change Docker's storage base directory (where container and images go) using the -goption when starting the Docker daemon. (check docker --help). You can have this setting applied automatically when Docker starts by adding it to /etc/default/docker

Why dict.get(key) instead of dict[key]?

get takes a second optional value. If the specified key does not exist in your dictionary, then this value will be returned.

dictionary = {"Name": "Harry", "Age": 17}
dictionary.get('Year', 'No available data')
>> 'No available data'

If you do not give the second parameter, None will be returned.

If you use indexing as in dictionary['Year'], nonexistent keys will raise KeyError.

ASP.NET 4.5 has not been registered on the Web server

For Windows 8 client computers, turn on "IIS-ASPNET45" in "Turn Windows Features On/Off" under "Internet Information Services-> World Wide Web Services -> Application Development Features -> ASP.NET 4.5".

Using Page_Load and Page_PreRender in ASP.Net

Page_Load happens after ViewState and PostData is sent into all of your server side controls by ASP.NET controls being created on the page. Page_Init is the event fired prior to ViewState and PostData being reinstated. Page_Load is where you typically do any page wide initilization. Page_PreRender is the last event you have a chance to handle prior to the page's state being rendered into HTML. Page_Load is the more typical event to work with.

Difference between int and double

Operations on integers are exact. double is a floating point data type, and floating point operations are approximate whenever there's a fraction.

double also takes up twice as much space as int in many implementations (e.g. most 32-bit systems) .

How to pass an object into a state using UI-router?

In version 0.2.13, You should be able to pass objects into $state.go,

$state.go('myState', {myParam: {some: 'thing'}})

$stateProvider.state('myState', {
                url: '/myState/{myParam:json}',
                params: {myParam: null}, ...

and then access the parameter in your controller.

$stateParams.myParam //should be {some: 'thing'}

myParam will not show up in the URL.


See the comment by christopherthielen, reproduced here for convenience:

christopherthielen: Yes, this should be working now in 0.2.13.

.state('foo', { url: '/foo/:param1?param2', params: { param3: null } // null is the default value });

$state.go('foo', { param1: 'bar', param2: 'baz', param3: { id: 35, name: 'what' } });

$stateParams in 'foo' is now { param1: 'bar', param2: 'baz', param3: { id: 35, name: 'what' } }

url is /foo/bar?param2=baz.

Show/hide forms using buttons and JavaScript

There's something I bet you already heard about this! It's called jQuery.

$("#button1").click(function() {

It's really easy and you can use CSS-like selectors and you can add animations. It's really easy to learn.

Create session factory in Hibernate 4

Try this!

package your.package;

import org.hibernate.HibernateException;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateUtil
    private static SessionFactory sessionFactory;
    private static ServiceRegistry serviceRegistry;

//          Configuration configuration = new Configuration();
            Configuration configuration = new Configuration().configure();

            serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        catch (HibernateException he)
            System.err.println("Error creating Session: " + he);
            throw new ExceptionInInitializerError(he);

    public static SessionFactory getSessionFactory()
        return sessionFactory;

How to clear the canvas for redrawing

in webkit you need to set the width to a different value, then you can set it back to the initial value

"insufficient memory for the Java Runtime Environment " message in eclipse

Try to modify your eclipse.ini with below


Once you open your eclipse you can try below

Looks like your application consumes more memory than allocated (Default). I will try two things

  1. As suggested by Harmlezz increase your memory allocation to JVM to -Xms2g -Xmx2g (If needed increase it more and try it out)

  2. Download eclipse memory analyzer and check for what causing memory leak OR even you can use JConsole to see JVM memory utilization in order to figure out application memory leak issue.

How to place div in top right hand corner of page

You can use css float

<div style='float: left;'><a href="login.php">Log in</a></div>

<div style='float: right;'><a href="home.php">Back to Home</a></div>

Have a look at this CSS Positioning

How to append multiple items in one line in Python

use for loop. like this:

for x in [1,2,7,8,9,10,13,14,19,20,21,22]:
    new_list.append(my_list[i + x])

Get type name without full namespace

typeof(T).Name // class name, no namespace
typeof(T).FullName // namespace and class name
typeof(T).Namespace // namespace, no class name

How to do a SOAP Web Service call from Java class?

I understand your problem boils down to how to call a SOAP (JAX-WS) web service from Java and get its returning object. In that case, you have two possible approaches:

  1. Generate the Java classes through wsimport and use them; or
  2. Create a SOAP client that:
    1. Serializes the service's parameters to XML;
    2. Calls the web method through HTTP manipulation; and
    3. Parse the returning XML response back into an object.

About the first approach (using wsimport):

I see you already have the services' (entities or other) business classes, and it's a fact that the wsimport generates a whole new set of classes (that are somehow duplicates of the classes you already have).

I'm afraid, though, in this scenario, you can only either:

  • Adapt (edit) the wsimport generated code to make it use your business classes (this is difficult and somehow not worth it - bear in mind everytime the WSDL changes, you'll have to regenerate and readapt the code); or
  • Give up and use the wsimport generated classes. (In this solution, you business code could "use" the generated classes as a service from another architectural layer.)

About the second approach (create your custom SOAP client):

In order to implement the second approach, you'll have to:

  1. Make the call:
    • Use the SAAJ (SOAP with Attachments API for Java) framework (see below, it's shipped with Java SE 1.6 or above) to make the calls; or
    • You can also do it through (and some handling).
  2. Turn the objects into and back from XML:
    • Use an OXM (Object to XML Mapping) framework such as JAXB to serialize/deserialize the XML from/into objects
    • Or, if you must, manually create/parse the XML (this can be the best solution if the received object is only a little bit differente from the sent one).

Creating a SOAP client using classic is not that hard (but not that simple either), and you can find in this link a very good starting code.

I recommend you use the SAAJ framework:

SOAP with Attachments API for Java (SAAJ) is mainly used for dealing directly with SOAP Request/Response messages which happens behind the scenes in any Web Service API. It allows the developers to directly send and receive soap messages instead of using JAX-WS.

See below a working example (run it!) of a SOAP web service call using SAAJ. It calls this web service.

import javax.xml.soap.*;

public class SOAPClientSAAJ {

    // SAAJ - SOAP Client Testing
    public static void main(String args[]) {
            The example below requests from the Web Service at:

            To call other WS, change the parameters below, which are:
             - the SOAP Endpoint URL (that is, where the service is responding from)
             - the SOAP Action

            Also change the contents of the method createSoapEnvelope() in this class. It constructs
             the inner part of the SOAP envelope that is actually sent.
        String soapEndpointUrl = "";
        String soapAction = "";

        callSoapWebService(soapEndpointUrl, soapAction);

    private static void createSoapEnvelope(SOAPMessage soapMessage) throws SOAPException {
        SOAPPart soapPart = soapMessage.getSOAPPart();

        String myNamespace = "myNamespace";
        String myNamespaceURI = "";

        // SOAP Envelope
        SOAPEnvelope envelope = soapPart.getEnvelope();
        envelope.addNamespaceDeclaration(myNamespace, myNamespaceURI);

            Constructed SOAP Request Message:
            <SOAP-ENV:Envelope xmlns:SOAP-ENV="" xmlns:myNamespace="">

        // SOAP Body
        SOAPBody soapBody = envelope.getBody();
        SOAPElement soapBodyElem = soapBody.addChildElement("CelsiusToFahrenheit", myNamespace);
        SOAPElement soapBodyElem1 = soapBodyElem.addChildElement("Celsius", myNamespace);

    private static void callSoapWebService(String soapEndpointUrl, String soapAction) {
        try {
            // Create SOAP Connection
            SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
            SOAPConnection soapConnection = soapConnectionFactory.createConnection();

            // Send SOAP Message to SOAP Server
            SOAPMessage soapResponse =, soapEndpointUrl);

            // Print the SOAP Response
            System.out.println("Response SOAP Message:");

        } catch (Exception e) {
            System.err.println("\nError occurred while sending SOAP Request to Server!\nMake sure you have the correct endpoint URL and SOAPAction!\n");

    private static SOAPMessage createSOAPRequest(String soapAction) throws Exception {
        MessageFactory messageFactory = MessageFactory.newInstance();
        SOAPMessage soapMessage = messageFactory.createMessage();


        MimeHeaders headers = soapMessage.getMimeHeaders();
        headers.addHeader("SOAPAction", soapAction);


        /* Print the request message, just for debugging purposes */
        System.out.println("Request SOAP Message:");

        return soapMessage;


About using JAXB for serializing/deserializing, it is very easy to find information about it. You can start here:

python convert list to dictionary

If you are still thinking what the! You would not be alone, its actually not that complicated really, let me explain.

How to turn a list into a dictionary using built-in functions only

We want to turn the following list into a dictionary using the odd entries (counting from 1) as keys mapped to their consecutive even entries.

l = ["a", "b", "c", "d", "e"]


To create a dictionary we can use the built in dict function for Mapping Types as per the manual the following methods are supported.

dict(one=1, two=2)
dict({'one': 1, 'two': 2})
dict(zip(('one', 'two'), (1, 2)))
dict([['two', 2], ['one', 1]])

The last option suggests that we supply a list of lists with 2 values or (key, value) tuples, so we want to turn our sequential list into:

l = [["a", "b"], ["c", "d"], ["e",]]

We are also introduced to the zip function, one of the built-in functions which the manual explains:

returns a list of tuples, where the i-th tuple contains the i-th element from each of the arguments

In other words if we can turn our list into two lists a, c, e and b, d then zip will do the rest.

slice notation

Slicings which we see used with Strings and also further on in the List section which mainly uses the range or short slice notation but this is what the long slice notation looks like and what we can accomplish with step:

>>> l[::2]
['a', 'c', 'e']

>>> l[1::2]
['b', 'd']

>>> zip(['a', 'c', 'e'], ['b', 'd'])
[('a', 'b'), ('c', 'd')]

>>> dict(zip(l[::2], l[1::2]))
{'a': 'b', 'c': 'd'}

Even though this is the simplest way to understand the mechanics involved there is a downside because slices are new list objects each time, as can be seen with this cloning example:

>>> a = [1, 2, 3]
>>> b = a
>>> b
[1, 2, 3]

>>> b is a

>>> b = a[:]
>>> b
[1, 2, 3]

>>> b is a

Even though b looks like a they are two separate objects now and this is why we prefer to use the grouper recipe instead.

grouper recipe

Although the grouper is explained as part of the itertools module it works perfectly fine with the basic functions too.

Some serious voodoo right? =) But actually nothing more than a bit of syntax sugar for spice, the grouper recipe is accomplished by the following expression.


Which more or less translates to two arguments of the same iterator wrapped in a list, if that makes any sense. Lets break it down to help shed some light.

zip for shortest

>>> l*2
['a', 'b', 'c', 'd', 'e', 'a', 'b', 'c', 'd', 'e']

>>> [l]*2
[['a', 'b', 'c', 'd', 'e'], ['a', 'b', 'c', 'd', 'e']]

>>> [iter(l)]*2
[<listiterator object at 0x100486450>, <listiterator object at 0x100486450>]

>>> zip([iter(l)]*2)
[(<listiterator object at 0x1004865d0>,),(<listiterator object at 0x1004865d0>,)]

>>> zip(*[iter(l)]*2)
[('a', 'b'), ('c', 'd')]

>>> dict(zip(*[iter(l)]*2))
{'a': 'b', 'c': 'd'}

As you can see the addresses for the two iterators remain the same so we are working with the same iterator which zip then first gets a key from and then a value and a key and a value every time stepping the same iterator to accomplish what we did with the slices much more productively.

You would accomplish very much the same with the following which carries a smaller What the? factor perhaps.

>>> it = iter(l)     
>>> dict(zip(it, it))
{'a': 'b', 'c': 'd'}

What about the empty key e if you've noticed it has been missing from all the examples which is because zip picks the shortest of the two arguments, so what are we to do.

Well one solution might be adding an empty value to odd length lists, you may choose to use append and an if statement which would do the trick, albeit slightly boring, right?

>>> if len(l) % 2:
...     l.append("")

>>> l
['a', 'b', 'c', 'd', 'e', '']

>>> dict(zip(*[iter(l)]*2))
{'a': 'b', 'c': 'd', 'e': ''}

Now before you shrug away to go type from itertools import izip_longest you may be surprised to know it is not required, we can accomplish the same, even better IMHO, with the built in functions alone.

map for longest

I prefer to use the map() function instead of izip_longest() which not only uses shorter syntax doesn't require an import but it can assign an actual None empty value when required, automagically.

>>> l = ["a", "b", "c", "d", "e"]
>>> l
['a', 'b', 'c', 'd', 'e']

>>> dict(map(None, *[iter(l)]*2))
{'a': 'b', 'c': 'd', 'e': None} 

Comparing performance of the two methods, as pointed out by KursedMetal, it is clear that the itertools module far outperforms the map function on large volumes, as a benchmark against 10 million records show.

$ time python -c 'dict(map(None, *[iter(range(10000000))]*2))'
real    0m3.755s
user    0m2.815s
sys     0m0.869s
$ time python -c 'from itertools import izip_longest; dict(izip_longest(*[iter(range(10000000))]*2, fillvalue=None))'
real    0m2.102s
user    0m1.451s
sys     0m0.539s

However the cost of importing the module has its toll on smaller datasets with map returning much quicker up to around 100 thousand records when they start arriving head to head.

$ time python -c 'dict(map(None, *[iter(range(100))]*2))'
real    0m0.046s
user    0m0.029s
sys     0m0.015s
$ time python -c 'from itertools import izip_longest; dict(izip_longest(*[iter(range(100))]*2, fillvalue=None))'
real    0m0.067s
user    0m0.042s
sys     0m0.021s

$ time python -c 'dict(map(None, *[iter(range(100000))]*2))'
real    0m0.074s
user    0m0.050s
sys     0m0.022s
$ time python -c 'from itertools import izip_longest; dict(izip_longest(*[iter(range(100000))]*2, fillvalue=None))'
real    0m0.075s
user    0m0.047s
sys     0m0.024s

See nothing to it! =)


How to remove all line breaks from a string

To remove new line chars use this:

yourString.replace(/\r?\n?/g, '')

Then you can trim your string to remove leading and trailing spaces:


Hide/Show Column in an HTML Table

I would like to do this without attaching a class to every td

Personally, I would go with the the class-on-each-td/th/col approach. Then you can switch columns on and off using a single write to className on the container, assuming style rules like:

table.hide1 .col1 { display: none; }
table.hide2 .col2 { display: none; }

This is going to be faster than any JS loop approach; for really long tables it can make a significant difference to responsiveness.

If you can get away with not supporting IE6, you could use adjacency selectors to avoid having to add the class attributes to tds. Or alternatively, if your concern is making the markup cleaner, you could add them from JavaScript automatically in an initialisation step.

How to get the full path of running process?

 using System.Diagnostics;
 var process = Process.GetCurrentProcess(); // Or whatever method you are using
 string fullPath = process.MainModule.FileName;
 //fullPath has the path to exe.

There is one catch with this API, if you are running this code in 32 bit application, you'll not be able to access 64-bit application paths, so you'd have to compile and run you app as 64-bit application (Project Properties ? Build ? Platform Target ? x64).

How do I split a string with multiple separators in JavaScript?

For fun, I solved this with reduce and filter. In real life I would probably use Aarons answere here. Nevertheless I think my version isn't totally unreadable or inefficient:

[' ','_','-','.',',',':','@'].reduce(
(segs, sep) => segs.reduce(
(out, seg) => out.concat(seg.split(sep)), []), 
['E-mail Address: [email protected], Phone Number: +1-800-555-0011']
).filter(x => x)

Or as a function:

function msplit(str, seps) {
  return seps.reduce((segs, sep) => segs.reduce(
    (out, seg) => out.concat(seg.split(sep)), []
  ), [str]).filter(x => x);

This will output:


Without the filter at the end you would get empty strings in the array where two different separators are next to each other.

Bootstrap tab activation with JQuery

Applying a selector from the .nav-tabs seems to be working: See this demo.


function activaTab(tab){
    $('.nav-tabs a[href="#' + tab + '"]').tab('show');

I would prefer @codedme's answer, since if you know which tab you want prior to page load, you should probably change the page html and not use JS for this particular task.

I tweaked the demo for his answer, as well.

(If this is not working for you, please specify your setting - browser, environment, etc.)

How to launch an Activity from another Application in Android

// check for the app if it exist in the phone it will lunch it otherwise, it will search for the app in google play app in the phone and to avoid any crash, if no google play app installed in the phone, it will search for the app in the google play store using the browser : 

 public void onLunchAnotherApp() {

        final String appPackageName = getApplicationContext().getPackageName();

        Intent intent = getPackageManager().getLaunchIntentForPackage(appPackageName);
        if (intent != null) {


        } else {

            onGoToAnotherInAppStore(intent, appPackageName);



    public void onGoToAnotherInAppStore(Intent intent, String appPackageName) {

        try {

            intent = new Intent(Intent.ACTION_VIEW);
            intent.setData(Uri.parse("market://details?id=" + appPackageName));

        } catch (android.content.ActivityNotFoundException anfe) {

            intent = new Intent(Intent.ACTION_VIEW);
            intent.setData(Uri.parse("" + appPackageName));



Check if a file exists or not in Windows PowerShell?

You want to use Test-Path:

Test-Path <path to file> -PathType Leaf

AppendChild() is not a function javascript

Just change

var div = '<div>top div</div>'; // you just created a text string


var div = document.createElement("div"); // we want a DIV element instead
div.innerHTML = "top div";

Can I change the viewport meta tag in mobile safari on the fly?

in your <head>

<meta id="viewport"
      content="width=1024, height=768, initial-scale=0, minimum-scale=0.25" />

somewhere in your javascript

      "initial-scale=0.5; maximum-scale=1.0; user-scalable=0;");

... but good luck with tweaking it for your device, fiddling for hours... and i'm still not there!


Boolean checking in the 'if' condition

I would suggest that you do:

if (status) {
    //positive work
} else {
    // negative work

The == tests, while obviously redundant, also run the risk of a single = typo which would result in an assignment.

How to convert an integer (time) to HH:MM:SS::00 in SQL Server 2008?

declare @T int

set @T = 10455836
--set @T = 421151

select (@T / 1000000) % 100 as hour,
       (@T / 10000) % 100 as minute,
       (@T / 100) % 100 as second,
       (@T % 100) * 10 as millisecond

select dateadd(hour, (@T / 1000000) % 100,
       dateadd(minute, (@T / 10000) % 100,
       dateadd(second, (@T / 100) % 100,
       dateadd(millisecond, (@T % 100) * 10, cast('00:00:00' as time(2))))))  


hour        minute      second      millisecond
----------- ----------- ----------- -----------
10          45          58          360

(1 row(s) affected)


(1 row(s) affected)

React Router v4 - How to get current route?

Here is a solution using history Read more

import { createBrowserHistory } from "history";

const history = createBrowserHistory()

inside Router


Create an empty list in python with certain size

Make it more reusable as a function.

def createEmptyList(length,fill=None):
    return a (empty) list of a given length
        print createEmptyList(3,-1)
        >> [-1, -1, -1]
        print createEmptyList(4)
        >> [None, None, None, None]
    return [fill] * length

Composer killed while updating

Fix for AWS ec2 Ubuntu Server Php Memory Value Upgrade For Magento 2.3.X

  • Php 7.2 / 7.3
  • nginx
  • ubuntu
  • composer 1.X
  • mariaDB
  • magento 2.3.X

Error : Updating dependencies (including require-dev) Killed for

  1. Ram Must at least 4GB
  2. Change instance type to suitable or Upgrade Ram
  3. Php Memory Value change
  4. Server Restart
  5. Try to install the same package again

PHP value update may locate under '/etc/php/7.2/fpm/php.ini' depend on your server and PHP fpm X.XX version

Using Seed command 'change as your server requires' on my case >> /etc/php/7.2/fpm/php.ini

memory limit type as "3.5G" or "3500MB" Php 7.2.X

sudo sed -i "s/memory_limit = .*/memory_limit = 3.5G/" /etc/php/7.2/fpm/php.ini

Php 7.3.X

  sudo sed -i "s/memory_limit = .*/memory_limit = 3.5G/" /etc/php/7.3/fpm/php.ini

Test if applied on 'free -h' command

    free -h

Install-Package Again#

Install extension via Composer

go to your Magento 2 installation directory

cd /var/www/html/

with 'superuser' privileges

sudo su

Start installation

composer require XXXXXX/XXXXXXX

Enable Module s

php bin/magento module:enable XXXXXX/XXXXXXX

php bin/magento setup:upgrade
php bin/magento setup:di:compile
php bin/magento setup:static-content:deploy
sudo reboot


How to ignore the certificate check when ssl

Just incidentally, this is a the least verbose way of turning off all certificate validation in a given app that I know of:

ServicePointManager.ServerCertificateValidationCallback = (a, b, c, d) => true;

How to show text in combobox when no item selected?

Why not do it XAML?

<ComboBox x:Name="myComboBoxMenu" PlaceholderText="Hello"/>

Remove CSS from a Div using JQuery

Before adding a class you should check if it already had class with .hasClass() method

For your specific question. You should be putting your stuff in Cascading Stylesheet. It's best practice to separate design and functionality.

so the proposed solution of adding and removing class names is best practice.

however when you are manipulating elements you don't control of how they are rendered. removeAttr('style') is BEST way to remove all inline styles.

Sql select rows containing part of string

You can use the LIKE operator to compare the content of a T-SQL string, e.g.

SELECT * FROM [table] WHERE [field] LIKE '%stringtosearchfor%'.

The percent character '%' is a wild card- in this case it says return any records where [field] at least contains the value "stringtosearchfor".

what does "dead beef" mean?

It was used as a pattern to store in memory as a series of hex bytes (0xde, 0xad, 0xbe, 0xef). You could see if memory was corrupted because of hardware failure, buffer overruns, etc.

Python: Find index of minimum item in list of floats

You're effectively scanning the list once to find the min value, then scanning it again to find the index, you can do both in one go:

from operator import itemgetter
min(enumerate(a), key=itemgetter(1))[0] 

Position of a string within a string using Linux shell script?

I used awk for this

a="The cat sat on the mat"
awk -v a="$a" -v b="$test" 'BEGIN{print index(a,b)}'

How to compile a c++ program in Linux?

As the other answers say, use g++ instead of gcc.

Or use make: make hi

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

in ActivitySaludo, this line,


you must set the content view for the activity only once.

Print array to a file

Here is what I learned in last 17 hours which solved my problem while searching for a similar solution.


Specific Code :

// The following is okay, as it's inside a string. Constants are not looked for
// within strings, so no E_NOTICE occurs here
print "Hello $arr[fruit]";      // Hello apple

What I took from above, $arr[fruit] can go inside " " (double quotes) and be accepted as string by PHP for further processing.

Second Resource is the code in one of the answers above:

file_put_contents($file, print_r($array, true), FILE_APPEND)

This is the second thing I didn't knew, FILE_APPEND.

What I was trying to achieve is get contents from a file, edit desired data and update the file with new data but after deleting old data.

Now I only need to know how to delete data from file before adding updated data.

About other solutions:

Just so that it may be helpful to other people; when I tried var_export or Print_r or Serialize or Json.Encode, I either got special characters like => or ; or ' or [] in the file or some kind of error. Tried too many things to remember all errors. So if someone may want to try them again (may have different scenario than mine), they may expect errors.

About reading file, editing and updating:

I used fgets() function to load file array into a variable ($array) and then use unset($array[x]) (where x stands for desired array number, 1,2,3 etc) to remove particular array. Then use array_values() to re-index and load the array into another variable and then use a while loop and above solutions to dump the array (without any special characters) into target file.


while ($x <= $lines-1) //$lines is count($array) i.e. number of lines in array $array
        $txt= "$array[$x]";
        file_put_contents("file.txt", $txt, FILE_APPEND);

jQuery .get error response function?

$.get does not give you the opportunity to set an error handler. You will need to use the low-level $.ajax function instead:

    url: '',
    type: 'GET',
    success: function(data){ 
        $(data).find('#reviews .card').appendTo('#reviews');
    error: function(data) {
        alert('woops!'); //or whatever

Edit March '10

Note that with the new jqXHR object in jQuery 1.5, you can set an error handler after calling $.get:

$.get('', function(data){ 
    $(data).find('#reviews .card').appendTo('#reviews');
}).fail(function() {
    alert('woops'); // or whatever

How to find and restore a deleted file in a Git repository

I had the same question. Without knowing it, I had created a dangling commit.

List dangling commits

git fsck --lost-found

Inspect each dangling commit

git reset --hard <commit id>

My files reappeared when I moved to the dangling commit.

git status for the reason:

“HEAD detached from <commit id where it detached>”

How to convert int[] into List<Integer> in Java?

Also from guava libraries...

List<Integer> Ints.asList(int...)

How to get the last row of an Oracle a table

$sql = "INSERT INTO table_name( field1, field2 )  VALUES ('foo','bar') 
        RETURNING ID INTO :mylastid";
$stmt = oci_parse($db, $sql);
oci_bind_by_name($stmt, "mylastid", $last_id, 8, SQLT_INT);

echo "last inserted id is:".$last_id;

Tip: you have to use your id column name in {your_id_col_name} below...

"RETURNING {your_id_col_name} INTO :mylastid"

How to properly create an SVN tag from trunk?

Another option to tag a Subversion repository is to add the tag to the svn:log property like this:

   echo "TAG: your_tag_text" > newlog
   svn propget $REPO --revprop -r $tagged_revision >> newlog
   svn propset $REPO --revprop -r $tagged_revision -F newlog
   rm newlog

I recently started thinking that this is the most "right" way to tag. This way you don't create extra revisions (as you do with "svn cp") and still can easily extract all tags by using grep on "svn log" output:

   svn log | awk '/----/ {
                  /^r[[:digit:]]+/ {
                      if(expect_rev) {
                  /^TAG:/ {
                      if(expect_tag) {
                          print "Revision "rev", Tag: "$2;

Also, this way you may seamlessly delete tags if you need to. So the tags become a complete meta-information, and I like it.

Cleaning up old remote git branches

This command will "dry run" delete all remote (origin) merged branches, apart from master. You can change that, or, add additional branches after master: grep -v for-example-your-branch-here |

git branch -r --merged | 
  grep origin | 
  grep -v '>' | 
  grep -v master | 
  xargs -L1 | 
  awk '{sub(/origin\//,"");print}'| 
  xargs git push origin --delete --dry-run

If it looks good, remove the --dry-run. Additionally, you may like to test this on a fork first.

How to make Toolbar transparent?

Add below code to styles.xml file

<style name="LayoutPageTheme" parent="@style/Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowActionBarOverlay">true</item>
    <!-- Support library compatibility -->
    <item name="windowActionBarOverlay">true</item>
    <item name="android:actionBarStyle">@style/TransparentActionBar</item>
<!-- ActionBar styles -->
<style name="TransparentActionBar"
    <item name="android:background">@android:color/transparent</item>

            app:popupTheme="@style/AppTheme.PopupOverlay" />

Don't forget to write: android:background="@android:color/transparent"

The most efficient way to remove first N elements in a list?

l = [1, 2, 3, 4, 5]
del l[0:3] # Here 3 specifies the number of items to be deleted.

This is the code if you want to delete a number of items from the list. You might as well skip the zero before the colon. It does not have that importance. This might do as well.

l = [1, 2, 3, 4, 5]
del l[:3] # Here 3 specifies the number of items to be deleted.

Putty: Getting Server refused our key Error

Oh my God I spent days trying to fix this. So here is what worked for me. I went back to the root fold like this: cd /root/ mkdir .ssh cd .ssh chmod 700 .ssh nano -w authorized_keys service ssh restart So I used root to logging via Putty and it worked. so try to do the same with the user you want to use in putty.

Python module os.chmod(file, 664) does not change the permission to rw-rw-r-- but -w--wx----

Using the stat.* bit masks does seem to me the most portable and explicit way of doing this. But on the other hand, I often forget how best to handle that. So, here's an example of masking out the 'group' and 'other' permissions and leaving 'owner' permissions untouched. Using bitmasks and subtraction is a useful pattern.

import os
import stat
def chmodme(pn):
    """Removes 'group' and 'other' perms. Doesn't touch 'owner' perms."""
    mode = os.stat(pn).st_mode
    mode -= (mode & (stat.S_IRWXG | stat.S_IRWXO))
    os.chmod(pn, mode)

What is /var/www/html?

In the most shared hosts you can't set it.

On a VPS or dedicated server, you can set it, but everything has its price.

On shared hosts, in general you receive a Linux account, something such as /home/(your username)/, and the equivalent of /var/www/html turns to /home/(your username)/public_html/ (or something similar, such as /home/(your username)/www)

If you're accessing your account via FTP, you automatically has accessing the your */home/(your username)/ folder, just find the www or public_html and put your site in it.

If you're using absolute path in the code, bad news, you need to refactor it to use relative paths in the code, at least in a shared host.

Working with time DURATION, not time of day

Let's say that you want to display the time elapsed between 5pm on Monday and 2:30pm the next day, Tuesday.

In cell A1 (for example), type in the date. In A2, the time. (If you type in 5 pm, including the space, it will display as 5:00 PM. If you want the day of the week to display as well, then in C3 (for example) enter the formula, =A1, then highlight the cell, go into the formatting dropdown menu, select Custom, and type in dddd.

Repeat all this in the row below.

Finally, say you want to display that duration in cell D2. Enter the formula, =(a2+b2)-(a1+b1). If you want this displayed as "22h 30m", select the cell, and in the formatting menu under Custom, type in h"h" m"m".

Better way of getting time in milliseconds in javascript?

As far that I know you only can get time with Date. is the solution but is not available everywhere :

var currentTime = +new Date();

This gives you the current time in milliseconds.

For your jumps. If you compute interpolations correctly according to the delta frame time and you don't have some rounding number error, I bet for the garbage collector (GC).

If there is a lot of created temporary object in your loop, garbage collection has to lock the thread to make some cleanup and memory re-organization.

With Chrome you can see how much time the GC is spending in the Timeline panel.

EDIT: Since my answer, should be considered as the best option as it is supported everywhere and on IE >= 9.

node.js: cannot find module 'request'

I was running into the same problem, here is how I got it working..

open terminal:

mkdir testExpress
cd testExpress
npm install request


sudo npm install -g request // If you would like to globally install.

now don't use

node app.js or node test.js, you will run into this problem doing so. You can also print the problem that is being cause by using this command.. "node -p app.js"

The above command to start nodeJs has been deprecated. Instead use

npm start

You should see this..

[email protected] start /Users/{username}/testExpress
node ./bin/www

Open your web browser and check for localhost:3000

You should see Express install (Welcome to Express)

javascript onclick increment number

In its most basic incarnation..


    var i = 0;
    function buttonClick() {
        document.getElementById('inc').value = ++i;


<button onclick="buttonClick()">Click Me</button>
<input type="text" id="inc" value="0"></input>

Set custom attribute using JavaScript

Use the setAttribute method:

document.getElementById('item1').setAttribute('data', "icon: 'base2.gif', url: 'output.htm', target: 'AccessPage', output: '1'");

But you really should be using data followed with a dash and with its property, like:

<li ... data-icon="base.gif" ...>

And to do it in JS use the dataset property:

document.getElementById('item1').dataset.icon = "base.gif";

Storing and Retrieving ArrayList values from hashmap

for (Map.Entry<String, ArrayList<Integer>> entry : map.entrySet()) {
 System.out.println( entry.getKey());     
 System.out.println( entry.getValue());//Returns the list of values

Javascript array sort and unique

How about:

array.sort().filter(function(elem, index, arr) {
  return index == arr.length - 1 || arr[index + 1] != elem

This is similar to @loostro answer but instead of using indexOf which will reiterate the array for each element to verify that is the first found, it just checks that the next element is different than the current.

Installing a pip package from within a Jupyter Notebook not working

conda create -n py27 python=2.7 ipykernel

source activate py27

pip install geocoder

How to add class active on specific li on user click with jQuery

        // Remove active for all items.
        $('.sidebar-menu li').removeClass('active');
        // highlight submenu item
        $('li a[href="' + this.location.pathname + '"]').parent().addClass('active');
        // Highlight parent menu item.
        $('ul a[href="' + this.location.pathname + '"]').parents('li').addClass('active')

The property 'value' does not exist on value of type 'HTMLElement'

The problem is here:


You know that HTMLElement returned from getElementById() is actually an instance of HTMLInputElement inheriting from it because you are passing an ID of input element. Similarly in statically typed Java this won't compile:

public Object foo() {
  return 42;


signum() is a method of Integer, but the compiler only knows the static type of foo(), which is Object. And Object doesn't have a signum() method.

But the compiler can't know that, it can only base on static types, not dynamic behaviour of your code. And as far as the compiler knows, the type of document.getElementById(elementId) expression does not have value property. Only input elements have value.

For a reference check HTMLElement and HTMLInputElement in MDN. I guess Typescript is more or less consistent with these.

dynamically add and remove view to viewpager

I was looking for simple solution to remove views from viewpager (no fragments) dynamically. So, if you have some info, that your pages belongs to, you can set it to View as tag. Just like that (adapter code):

public Object instantiateItem(ViewGroup collection, int position)
    ImageView iv = new ImageView(mContext);
    MediaMessage msg = mMessages.get(position);

    return iv;

public int getItemPosition (Object object)
    View o = (View) object;
    int index = mMessages.indexOf(o.getTag());
    if (index == -1)
        return POSITION_NONE;
        return index;

You just need remove your info from mMessages, and then call notifyDataSetChanged() for your adapter. Bad news there is no animation in this case.

Difference between FetchType LAZY and EAGER in Java Persistence API?

From the Javadoc:

The EAGER strategy is a requirement on the persistence provider runtime that data must be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime that data should be fetched lazily when it is first accessed.

E.g., eager is more proactive than lazy. Lazy only happens on first use (if the provider takes the hint), whereas with eager things (may) get pre-fetched.

In Windows cmd, how do I prompt for user input and use the result in another command?

@echo off
set /p input="Write something, it will be used in the command "echo""
echo %input%

if i get what you want, this works fine. you can use %input% in other commands too.

@echo off
echo Write something, it will be used in the command "echo"
set /p input=""
echo %input%

How can I check if a string represents an int, without using try/except?

with positive integers you could use .isdigit:

>>> '16'.isdigit()

it doesn't work with negative integers though. suppose you could try the following:

>>> s = '-17'
>>> s.startswith('-') and s[1:].isdigit()

it won't work with '16.0' format, which is similar to int casting in this sense.


def check_int(s):
    if s[0] in ('-', '+'):
        return s[1:].isdigit()
    return s.isdigit()

Github permission denied: ssh add agent has no identities

Run the following commands:

ssh-keygen -t rsa
ssh-add /Users/*yourUserNameHere*/.ssh/id_rsa** 
pbcopy < ~/.ssh/**

Go to your Github account :

1) Click : SSH and GPG keys

2) New SSH Key and Past it there

3) Add SSH Key


How to include route handlers in multiple files in Express?


const express = require("express");
const app = express();
const http = require('http');
const server = http.createServer(app).listen(3000);
const router = (global.router = (express.Router()));
app.use('/books', require('./routes/books'))
app.use('/users', require('./routes/users'))


const router = global.router
router.get('/', (req, res) => {
    res.jsonp({name: 'John Smith'})

module.exports = router


const router = global.router
router.get('/', (req, res) => {
    res.jsonp({name: 'Dreams from My Father by Barack Obama'})

module.exports = router

if you have your server running local (http://localhost:3000) then

// Users
curl --request GET 'localhost:3000/users' => {name: 'John Smith'}

// Books
curl --request GET 'localhost:3000/users' => {name: 'Dreams from My Father by Barack Obama'}

What is "android.R.layout.simple_list_item_1"?

android.R.layout.simple_list_item_1, this is row layout file in your res/layout folder which contains the corresponding design for your row in listview. Now we just bind the array list items to the row layout by using mylistview.setadapter(aa);

How to add an object to an ArrayList in Java

Contacts.add(objt.Data(name, address, contact));

This is not a perfect way to call a constructor. The constructor is called at the time of object creation automatically. If there is no constructor java class creates its own constructor.

The correct way is:

// object creation. 
Data object1 = new Data(name, address, contact);      

// adding Data object to ArrayList object Contacts.

How to change permissions for a folder and its subfolders/files in one step?

It's very simple.

In Terminal go to file manager. example: sudo nemo. Go /opt/ then click Properties ? Permission. and then Other. Finally, change to create and delete and file acess to read and write and click on button apply... And work.

'Static readonly' vs. 'const'

Constants are like the name implies, fields which don't change and are usually defined statically at compile time in the code.

Read-only variables are fields that can change under specific conditions.

They can be either initialized when you first declare them like a constant, but usually they are initialized during object construction inside the constructor.

They cannot be changed after the initialization takes place, in the conditions mentioned above.

Static read-only sounds like a poor choice to me since, if it's static and it never changes, so just use it public const. If it can change then it's not a constant and then, depending on your needs, you can either use read-only or just a regular variable.

Also, another important distinction is that a constant belongs to the class, while the read-only variable belongs to the instance!

JSON.Parse,'Uncaught SyntaxError: Unexpected token o

Maybe what comes from the server is already evaluated as JSON object? For example, using jQuery get method:

$.get('/service', function(data) {  
  var obj = data;

         "obj" is evaluated at this point if server responded 
         with "application/json" or similar.
      for (var i = 0; i < obj.length; i++) {

Alternatively, if you need to turn JSON object into JSON string literal, you can use JSON.stringify:

var json = [{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}];
var jsonString = JSON.stringify(json);

But in this case I don't understand why you can't just take the json variable and refer to it instead of stringifying and parsing.

How to load a model from an HDF5 file in Keras?

load_weights only sets the weights of your network. You still need to define its architecture before calling load_weights:

def create_model():
   model = Sequential()
   model.add(Dense(64, input_dim=14, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(64, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(2, init='uniform'))
   return model

def train():
   model = create_model()
   sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
   model.compile(loss='binary_crossentropy', optimizer=sgd)

   checkpointer = ModelCheckpoint(filepath="/tmp/weights.hdf5", verbose=1, save_best_only=True), y_train, nb_epoch=20, batch_size=16, show_accuracy=True, validation_split=0.2, verbose=2, callbacks=[checkpointer])

def load_trained_model(weights_path):
   model = create_model()

How should I tackle --secure-file-priv in MySQL?

If the file is local to your machine use the LOCAL in your command

LOAD DATA LOCAL INFILE "text.txt" INTO table mytable;

How to get screen dimensions as pixels in Android

There is a non-deprecated way to do this using DisplayMetrics (API 1), that avoids the try/catch messiness:

 // initialize the DisplayMetrics object
 DisplayMetrics deviceDisplayMetrics = new DisplayMetrics();

 // populate the DisplayMetrics object with the display characteristics

 // get the width and height
 screenWidth = deviceDisplayMetrics.widthPixels;
 screenHeight = deviceDisplayMetrics.heightPixels;

How to remove foreign key constraint in sql server?

If you find yourself in a situation where the FK name of a table has been auto-generated and you aren't able to view what it exactly is (in the case of not having rights to a database for instance) you could try something like this:

SELECT @table = N'dbo.Table';
SELECT @sql = 'ALTER TABLE ' + @table
    + ' DROP CONSTRAINT ' + NAME + ';'
    FROM sys.foreign_keys
    WHERE [type] = 'F'
    AND [parent_object_id] = OBJECT_ID(@table);
EXEC sp_executeSQL @sql;

Build up a stored proc which drops the constraint of the specified table without specifying the actual FK name. It drops the constraint where the object [type] is equal to F (Foreign Key constraint).

Note: if there are multiple FK's in the table it will drop them all. So this solution works best if the table you are targeting has just one FK.

How do you determine what SQL Tables have an identity column programmatically

Another potential way to do this for SQL Server, which has less reliance on the system tables (which are subject to change, version to version) is to use the INFORMATION_SCHEMA views:

order by TABLE_NAME 

Loop through the rows of a particular DataTable

You want to loop on the .Rows, and access the column for the row like q("column")


        For Each q In dtDataTable.Rows
            strDetail = q("Detail")

Also make sure to check msdn doc for any class you are using + use intellisense

Check synchronously if file/directory exists in Node.js

fs.exists() is deprecated dont use it

You could implement the core nodejs way used at this:

function statPath(path) {
  try {
    return fs.statSync(path);
  } catch (ex) {}
  return false;

this will return the stats object then once you've got the stats object you could try

var exist = statPath('/path/to/your/file.js');
if(exist && exist.isFile()) {
  // do something

Check if inputs are empty using jQuery

Doing it on blur is too limited. It assumes there was focus on the form field, so I prefer to do it on submit, and map through the input. After years of dealing with fancy blur, focus, etc. tricks, keeping things simpler will yield more usability where it counts.

$('#signupform').submit(function() {
    var errors = 0;
    $("#signupform :input").map(function(){
         if( !$(this).val() ) {
        } else if ($(this).val()) {
    if(errors > 0){
        $('#errorwarn').text("All fields are required");
        return false;
    // do the ajax..    

How to make a stable two column layout in HTML/CSS

Piece of cake.

Use 960Grids Go to the automatic layout builder and make a two column, fluid design. Build a left column to the width of grids that works....this is the only challenge using grids and it's very easy once you read a tutorial. In a nutshell, each column in a grid is a certain width, and you set the amount of columns you want to use. To get a column that's exactly a certain width, you have to adjust your math so that your column width is exact. Not too tough.

No chance of wrapping because others have already fought that battle for you. Compatibility back as far as you likely will ever need to go. Quick and easy....Now, download, customize and deploy.

Voila. Grids FTW.

How to generate a git patch for a specific commit?

git format-patch commit_Id~1..commit_Id  
git apply patch-file-name

Fast and simple solution.

Sending POST data without form

If you don't want your data to be seen by the user, use a PHP session.

Data in a post request is still accessible (and manipulable) by the user.

Checkout this tutorial on PHP Sessions.

How to use mod operator in bash?

for i in {1..600}

C++ Double Address Operator? (&&)

This is C++11 code. In C++11, the && token can be used to mean an "rvalue reference".

What is the difference between printf() and puts() in C?

(This is pointed out in a comment by Zan Lynx, but I think it deserves an aswer - given that the accepted answer doesn't mention it).

The essential difference between puts(mystr); and printf(mystr); is that in the latter the argument is interpreted as a formatting string. The result will be often the same (except for the added newline) if the string doesn't contain any control characters (%) but if you cannot rely on that (if mystr is a variable instead of a literal) you should not use it.

So, it's generally dangerous -and conceptually wrong- to pass a dynamic string as single argument of printf:

  char * myMessage;
  // ... myMessage gets assigned at runtime, unpredictable content
  printf(myMessage);  // <--- WRONG! (what if myMessage contains a '%' char?) 
  puts(myMessage);    // ok
  printf("%s\n",myMessage); // ok, equivalent to the previous, perhaps less efficient

The same applies to fputs vs fprintf (but fputs doesn't add the newline).

Unbound classpath container in Eclipse

Given the FAQ, sharing a project file seems have to have advantages and is even recommended practice for Java projects (personally, I would not do that).

Maybe some of the following work for you:

  1. Edit the project's properties (right-click project, Properties, Java Build Path, Libraries, Remove and Add Library.
  2. Import the project's files without the "project file"
  3. Install JDK1.5 from and see whether you can fix paths

Invisible characters - ASCII

There is actually a truly invisible character: U+FEFF. This character is called the Byte Order Mark and is related to the Unicode 8 system. It is a really confusing concept that can be explained HERE The Byte Order Mark or BOM for short is an invisible character that doesn't take up any space. You can copy the character bellow between the > and <.

Here is the character:

> <

How to catch this character in action:

  • Copy the character between the > and <,
  • Write a line of text, then randomly put your caret in the line of text
  • Paste the character in the line.
  • Go to the beginning of the line and press and hold the right arrow key.

You will notice that when your caret gets to the place you pasted the character, it will briefly stop for around half a second. This is becuase the caret is passing over the invisible character. Even though you can't see it doesn't mean it isn't there. The caret still sees that there is a character in that area that you pasted the BOM and will pass through it. Since the BOM is invisble, the caret will look like it has paused for a brief moment. You can past the BOM multiple times in an area and redo the steps above to really show the affect. Good luck!

EDIT: Sadly, Stackoverflow doesn't like the character. Here is an example from

Create a new RGB OpenCV image using Python?

The new cv2 interface for Python integrates numpy arrays into the OpenCV framework, which makes operations much simpler as they are represented with simple multidimensional arrays. For example, your question would be answered with:

import cv2  # Not actually necessary if you just want to create an image.
import numpy as np
blank_image = np.zeros((height,width,3), np.uint8)

This initialises an RGB-image that is just black. Now, for example, if you wanted to set the left half of the image to blue and the right half to green , you could do so easily:

blank_image[:,0:width//2] = (255,0,0)      # (B, G, R)
blank_image[:,width//2:width] = (0,255,0)

If you want to save yourself a lot of trouble in future, as well as having to ask questions such as this one, I would strongly recommend using the cv2 interface rather than the older cv one. I made the change recently and have never looked back. You can read more about cv2 at the OpenCV Change Logs.

TypeError: 'type' object is not subscriptable when indexing in to a dictionary

Normally Python throws NameError if the variable is not defined:

>>> d[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'd' is not defined

However, you've managed to stumble upon a name that already exists in Python.

Because dict is the name of a built-in type in Python you are seeing what appears to be a strange error message, but in reality it is not.

The type of dict is a type. All types are objects in Python. Thus you are actually trying to index into the type object. This is why the error message says that the "'type' object is not subscriptable."

>>> type(dict)
<type 'type'>
>>> dict[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'type' object is not subscriptable

Note that you can blindly assign to the dict name, but you really don't want to do that. It's just going to cause you problems later.

>>> dict = {1:'a'}
>>> type(dict)
<class 'dict'>
>>> dict[1]

The true source of the problem is that you must assign variables prior to trying to use them. If you simply reorder the statements of your question, it will almost certainly work:

d = {1: "walk1.png", 2: "walk2.png", 3: "walk3.png"}
m1 = pygame.image.load(d[1])
m2 = pygame.image.load(d[2])
m3 = pygame.image.load(d[3])
playerxy = (375,130)
window.blit(m1, (playerxy))

javascript get x and y coordinates on mouse click

It sounds like your printMousePos function should:

  1. Get the X and Y coordinates of the mouse
  2. Add those values to the HTML

Currently, it does this:

  1. Creates (undefined) variables for the X and Y coordinates of the mouse
  2. Attaches a function to the "mousemove" event (which will set those variables to the mouse coordinates when triggered by a mouse move)
  3. Adds the current values of your variables to the HTML

See the problem? Your variables are never getting set, because as soon as you add your function to the "mousemove" event you print them.

It seems like you probably don't need that mousemove event at all; I would try something like this:

function printMousePos(e) {
    var cursorX = e.pageX;
    var cursorY = e.pageY;
    document.getElementById('test').innerHTML = "x: " + cursorX + ", y: " + cursorY;