Programs & Examples On #Bea


Highlight Anchor Links when user manually scrolls?

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

Are all Spring Framework Java Configuration injection examples buggy?

In your test, you are comparing the two TestParent beans, not the single TestedChild bean.

Also, Spring proxies your @Configuration class so that when you call one of the @Bean annotated methods, it caches the result and always returns the same object on future calls.

See here:

Got a NumberFormatException while trying to parse a text file for objects

I changed Scanner fin = new Scanner(file); to Scanner fin = new Scanner(new File(file)); and it works perfectly now. I didn't think the difference mattered but there you go.

Call japplet from jframe

First of all, Applets are designed to be run from within the context of a browser (or applet viewer), they're not really designed to be added into other containers.

Technically, you can add a applet to a frame like any other component, but personally, I wouldn't. The applet is expecting a lot more information to be available to it in order to allow it to work fully.

Instead, I would move all of the "application" content to a separate component, like a JPanel for example and simply move this between the applet or frame as required...

ps- You can use f.setLocationRelativeTo(null) to center the window on the screen ;)


You need to go back to basics. Unless you absolutely must have one, avoid applets until you understand the basics of Swing, case in point...

Within the constructor of GalzyTable2 you are doing...

JApplet app = new JApplet(); add(app); app.init(); app.start(); 

...Why are you adding another applet to an applet??

Case in point...

Within the main method, you are trying to add the instance of JFrame to itself...

f.getContentPane().add(f, button2); 

Instead, create yourself a class that extends from something like JPanel, add your UI logical to this, using compound components if required.

Then, add this panel to whatever top level container you need.

Take the time to read through Creating a GUI with Swing

Updated with example

import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.event.ActionEvent; import javax.swing.ImageIcon; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException;  public class GalaxyTable2 extends JPanel {      private static final int PREF_W = 700;     private static final int PREF_H = 600;      String[] columnNames                     = {"Phone Name", "Brief Description", "Picture", "price",                         "Buy"};  // Create image icons     ImageIcon Image1 = new ImageIcon(                     getClass().getResource("s1.png"));     ImageIcon Image2 = new ImageIcon(                     getClass().getResource("s2.png"));     ImageIcon Image3 = new ImageIcon(                     getClass().getResource("s3.png"));     ImageIcon Image4 = new ImageIcon(                     getClass().getResource("s4.png"));     ImageIcon Image5 = new ImageIcon(                     getClass().getResource("note.png"));     ImageIcon Image6 = new ImageIcon(                     getClass().getResource("note2.png"));     ImageIcon Image7 = new ImageIcon(                     getClass().getResource("note3.png"));      Object[][] rowData = {         {"Galaxy S", "3G Support,CPU 1GHz",             Image1, 120, false},         {"Galaxy S II", "3G Support,CPU 1.2GHz",             Image2, 170, false},         {"Galaxy S III", "3G Support,CPU 1.4GHz",             Image3, 205, false},         {"Galaxy S4", "4G Support,CPU 1.6GHz",             Image4, 230, false},         {"Galaxy Note", "4G Support,CPU 1.4GHz",             Image5, 190, false},         {"Galaxy Note2 II", "4G Support,CPU 1.6GHz",             Image6, 190, false},         {"Galaxy Note 3", "4G Support,CPU 2.3GHz",             Image7, 260, false},};      MyTable ss = new MyTable(                     rowData, columnNames);      // Create a table     JTable jTable1 = new JTable(ss);      public GalaxyTable2() {         jTable1.setRowHeight(70);          add(new JScrollPane(jTable1),                         BorderLayout.CENTER);          JPanel buttons = new JPanel();          JButton button = new JButton("Home");         buttons.add(button);         JButton button2 = new JButton("Confirm");         buttons.add(button2);          add(buttons, BorderLayout.SOUTH);     }      @Override      public Dimension getPreferredSize() {         return new Dimension(PREF_W, PREF_H);     }      public void actionPerformed(ActionEvent e) {         new AMainFrame7().setVisible(true);     }      public static void main(String[] args) {          EventQueue.invokeLater(new Runnable() {             @Override             public void run() {                 try {                     UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());                 } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {                     ex.printStackTrace();                 }                  JFrame frame = new JFrame("Testing");                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                 frame.add(new GalaxyTable2());                 frame.pack();                 frame.setLocationRelativeTo(null);                 frame.setVisible(true);             }         });     } } 

You also seem to have a lack of understanding about how to use layout managers.

Take the time to read through Creating a GUI with Swing and Laying components out in a container

Schema validation failed with the following errors: Data path ".builders['app-shell']" should have required property 'class'

I have to say, if you don't want to change anything in package.json file, try to update your Node.js version to latest. (currently 12.13.1 LTS)

Access blocked by CORS policy: Response to preflight request doesn't pass access control check

If you are using Spring as Back-End server and especially using Spring Security then i found a solution by putting http.cors(); in the configure method. The method looks like that:

protected void configure(HttpSecurity http) throws Exception {
                .authorizeRequests() // authorize
                .anyRequest().authenticated() // all requests are authenticated


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


to use unverified ssl you can add this to your code:

import ssl
ssl._create_default_https_context = ssl._create_unverified_context

ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean

As for me, I removed the provided scope in tomcat dependency.

  <scope>provided</scope> // remove this scope

Axios handling errors

If I understand correctly you want then of the request function to be called only if request is successful, and you want to ignore errors. To do that you can create a new promise resolve it when axios request is successful and never reject it in case of failure.

Updated code would look something like this:

export function request(method, uri, body, headers) {
  let config = {
    method: method.toLowerCase(),
    url: uri,
    baseURL: API_URL,
    headers: { 'Authorization': 'Bearer ' + getToken() },
    validateStatus: function (status) {
      return status >= 200 && status < 400

  return new Promise(function(resolve, reject) {
      function (response) {
      function (error) {
        console.log('Show error notification!')


After Spring Boot 2.0 migration: jdbcUrl is required with driverClassName

In case you do need to define dataSource(), for example when you have multiple data sources, you can use:

@Autowired Environment env;

public DataSource customDataSource() {

    DriverManagerDataSource dataSource = new DriverManagerDataSource();

    return dataSource;


By setting up the dataSource yourself (instead of using DataSourceBuilder), it fixed my problem which you also had.

The always knowledgeable Baeldung has a tutorial which explains in depth.

Not able to pip install pickle in python 3.6

Pickle is a module installed for both Python 2 and Python 3 by default. See the standard library for 3.6.4 and 2.7.

Also to prove what I am saying is correct try running this script:

import pickle

This will print out the Pickle documentation showing you all the functions (and a bit more) it provides.

Or you can start the integrated Python 3.6 Module Docs and check there.

As a rule of thumb: if you can import the module without an error being produced then it is installed

The reason for the No matching distribution found for pickle is because libraries for included packages are not available via pip because you already have them (I found this out yesterday when I tried to install an integrated package).

If it's running without errors but it doesn't work as expected I would think that you made a mistake somewhere (perhaps quickly check the functions you are using in the docs). Python is very informative with it's errors so we generally know if something is wrong.

Python convert object to float

  • You can use pandas.Series.astype
  • You can do something like this :

    weather["Temp"] = weather.Temp.astype(float)
  • You can also use pd.to_numeric that will convert the column from object to float

  • For details on how to use it checkout this link :
  • Example :

    s = pd.Series(['apple', '1.0', '2', -3])
    print(pd.to_numeric(s, errors='ignore'))
    print(pd.to_numeric(s, errors='coerce'))
  • Output:

    0    apple
    1      1.0
    2        2
    3       -3
    dtype: object
    0    NaN
    1    1.0
    2    2.0
    3   -3.0
    dtype: float64
  • In your case you can do something like this:

    weather["Temp"] = pd.to_numeric(weather.Temp, errors='coerce')
  • Other option is to use convert_objects
  • Example is as follows

    >> pd.Series([1,2,3,4,'.']).convert_objects(convert_numeric=True)
    0     1
    1     2
    2     3
    3     4
    4   NaN
    dtype: float64
  • You can use this as follows:

    weather["Temp"] = weather.Temp.convert_objects(convert_numeric=True)
  • I have showed you examples because if any of your column won't have a number then it will be converted to NaN... so be careful while using it.

How to debug when Kubernetes nodes are in 'Not Ready' state

I recently started using VMWare Octant This is a better UI than the Kubernetes Dashboard. You can view the Kubernetes cluster and look at the details of the cluster and the PODS. This will allow you to check the logs and open a terminal into the POD(s).

How to sign in kubernetes dashboard?

You need to follow these steps before the token authentication

  1. Create a Cluster Admin service account

    kubectl create serviceaccount dashboard -n default
  2. Add the cluster binding rules to your dashboard account

    kubectl create clusterrolebinding dashboard-admin -n default --clusterrole=cluster-admin --serviceaccount=default:dashboard
  3. Get the secret token with this command

    kubectl get secret $(kubectl get serviceaccount dashboard -o jsonpath="{.secrets[0].name}") -o jsonpath="{.data.token}" | base64 --decode
  4. Choose token authentication in the Kubernetes dashboard login page enter image description here

  5. Now you can able to login

Can't create project on Netbeans 8.2

For anyone that wants to download jdk 8 without an oracle account: copy and paste the link. Jdk 15 didn't work for me so i tried using jdk 8 and it worked.

No String-argument constructor/factory method to deserialize from String value ('')

This exception says that you are trying to deserialize the object "Address" from string "\"\"" instead of an object description like "{…}". The deserializer can't find a constructor of Address with String argument. You have to replace "" by {} to avoid this error.

Java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException

Worked by lowering the spring boot starter parent to 1.5.13

    <relativePath/> <!-- lookup parent from repository -->

How to completely uninstall kubernetes

use kubeadm reset command. this will un-configure the kubernetes cluster.

How to send authorization header with axios

On non-simple http requests your browser will send a "preflight" request (an OPTIONS method request) first in order to determine what the site in question considers safe information to send (see here for the cross-origin policy spec about this). One of the relevant headers that the host can set in a preflight response is Access-Control-Allow-Headers. If any of the headers you want to send were not listed in either the spec's list of whitelisted headers or the server's preflight response, then the browser will refuse to send your request.

In your case, you're trying to send an Authorization header, which is not considered one of the universally safe to send headers. The browser then sends a preflight request to ask the server whether it should send that header. The server is either sending an empty Access-Control-Allow-Headers header (which is considered to mean "don't allow any extra headers") or it's sending a header which doesn't include Authorization in its list of allowed headers. Because of this, the browser is not going to send your request and instead chooses to notify you by throwing an error.

Any Javascript workaround you find that lets you send this request anyways should be considered a bug as it is against the cross origin request policy your browser is trying to enforce for your own safety.

tl;dr - If you'd like to send Authorization headers, your server had better be configured to allow it. Set your server up so it responds to an OPTIONS request at that url with an Access-Control-Allow-Headers: Authorization header.

RestClientException: Could not extract response. no suitable HttpMessageConverter found

Spring sets the default content-type to octet-stream when the response is missing that field. All you need to do is to add a message converter to fix this.

The origin server did not find a current representation for the target resource or is not willing to disclose that one exists

I had the same problem and spent about 6 hours to solve it. I didn't find that answer for exactly my situation so maybe it could be useful for somebody.

When I created project, I pointed GroupId in pom.xml as "myproject.myapp" but I didn't create first "prime" package with that name in the project, where would be other packages inside of this main package (like /src/main/app etc). When I created prime package "myproject.myapp" and moved other packages inside of it, the problem was solved.

The origin server did not find a current representation for the target resource or is not willing to disclose that one exists. on deploying to tomcat

Almost same problem get resolved by creating a geoexplorer.xml file in /opt/apache-tomcat-8.5.37/conf/Catalina/localhost content of geoexplorer.xml file is

<Context displayName="geoexplorer" docBase="/usr/share/opengeo/geoexplorer" path="/geoexplorer"/>

How to check if a key exists in Json Object and get its value

From the structure of your source Object, I would try:

containerObject= new JSONObject(container);
  JSONObject innerObject = containerObject.getJSONObject("LabelData");
        //Do with video

Export result set on Dbeaver to CSV

The problem was the box "open new connection" that was checked. So I couldn't use my temporary table.

Running Tensorflow in Jupyter Notebook

I believe a short video showing all the details if you have Anaconda is the following for mac (it is very similar to windows users as well) just open Anaconda navigator and everything is just the same (almost!)

Then go to jupyter notebook and code

!pip install tensorflow


import tensorflow as tf

It work for me! :)

'Field required a bean of type that could not be found.' error spring restful API using mongodb

Two types of mongo dependencies -


Two types of repositories -


Make sure you are using the right combination.

Vertical Align Center in Bootstrap 4

Place your content within a flexbox container that is 100% high i.e h-100. Then justify the content centrally by using justify-content-center class.

<section class="container h-100 d-flex justify-content-center">
    <div class="jumbotron my-auto">
        <h1 class="display-3">Hello, Malawi!</h1>

CORS error :Request header field Authorization is not allowed by Access-Control-Allow-Headers in preflight response

The res.header('Access-Control-Allow-Origin', '*'); wouldn't work with Autorization header. Just enable pre-flight request, using cors library:

var express = require('express')
var cors = require('cors')
var app = express()
app.options('*', cors())

MultipartException: Current request is not a multipart request

It looks like the problem is request to server is not a multi-part request. Basically you need to modify your client-side form. For example:

<form action="..." method="post" enctype="multipart/form-data">
  <input type="file" name="file" />

Hope this helps.

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled

I added @Component annotation from import org.springframework.stereotype.Component and the problem was solved.

ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

I ran this on MacOS /Applications/Python\ 3.6/Install\ Certificates.command

Consider defining a bean of type 'service' in your configuration [Spring boot]

Please make sure that you have added the dependency in pom.xml or gradle file


Using Axios GET with Authorization Header in React-Native App

For anyone else that comes across this post and might find it useful... There is actually nothing wrong with my code. I made the mistake of requesting client_credentials type access code instead of password access code (#facepalms). FYI I am using urlencoded post hence the use of querystring.. So for those that may be looking for some example code.. here is my full request

Big thanks to @swapnil for trying to help me debug this.

   const data = {
      grant_type: USER_GRANT_TYPE,
      client_id: CLIENT_ID,
      client_secret: CLIENT_SECRET,
      scope: SCOPE_INT,
      username: DEMO_EMAIL,
      password: DEMO_PASSWORD
    };, Querystring.stringify(data))   
   .then(response => {
      USER_TOKEN =;
      console.log('userresponse ' +; 
   .catch((error) => {
      console.log('error ' + error);   

const AuthStr = 'Bearer '.concat(USER_TOKEN); 
axios.get(URL, { headers: { Authorization: AuthStr } })
 .then(response => {
     // If request is good...
 .catch((error) => {
     console.log('error ' + error);

UnsatisfiedDependencyException: Error creating bean with name

See if your <context:component-scan base-package="your package "/> is missing in either config or context xml file

Caused by: org.flywaydb.core.api.FlywayException: Validate failed. Migration Checksum mismatch for migration 2

use this query in your local DB.

  1. select * from schema_version delete from schema_version where checksum Column = -1729781252;

    Note: -1729781252 is the "Resolved locally" value.

  2. Build and start the server.

Vue - Deep watching an array of objects and calculating the change?

Your comparison function between old value and new value is having some issue. It is better not to complicate things so much, as it will increase your debugging effort later. You should keep it simple.

The best way is to create a person-component and watch every person separately inside its own component, as shown below:

<person-component :person="person" v-for="person in people"></person-component>

Please find below a working example for watching inside person component. If you want to handle it on parent side, you may use $emit to send an event upwards, containing the id of modified person.

Vue.component('person-component', {_x000D_
    props: ["person"],_x000D_
    template: `_x000D_
        <div class="person">_x000D_
            <input type='text' v-model='person.age'/>_x000D_
    watch: {_x000D_
        person: {_x000D_
            handler: function(newValue) {_x000D_
                console.log("Person with ID:" + + " modified")_x000D_
                console.log("New age: " + newValue.age)_x000D_
            deep: true_x000D_
new Vue({_x000D_
    el: '#app',_x000D_
    data: {_x000D_
        people: [_x000D_
          {id: 0, name: 'Bob', age: 27},_x000D_
          {id: 1, name: 'Frank', age: 32},_x000D_
          {id: 2, name: 'Joe', age: 38}_x000D_
<script src="[email protected]/dist/vue.js"></script>_x000D_
    <div id="app">_x000D_
        <p>List of people:</p>_x000D_
        <person-component :person="person" v-for="person in people"></person-component>_x000D_

Sending the bearer token with axios

By using Axios interceptor:

const service = axios.create({
  timeout: 20000 // request timeout

// request interceptor

  config => {
    // Do something before request is sent

    config.headers["Authorization"] = "bearer " + getToken();
    return config;
  error => {

Changing background color of selected item in recyclerview

I made this implementation in kotlin I thing is not very efficient but works ivIsSelected is a ImageView that represent in my case a check mark

var selectedItems = mutableListOf<Int>(-1)

override fun onBindViewHolder(holder: ContactViewHolder, position: Int) {
    // holder.setData(ContactViewModel, position)  // I'm passing this to the ViewHolder
    holder.itemView.ivIsSelected.visibility = INVISIBLE
    selectedItems.forEach {
        if (it == position) {
            holder.itemView.setBackgroundColor(Color.argb(45, 0, 255, 43))
            holder.itemView.ivIsSelected.visibility = VISIBLE

    holder.itemView.setOnClickListener { it ->
        selectedItems.forEach { selectedItem ->  // this forEach is required to refresh all the list


Spring security CORS Filter

With Spring Security in Spring Boot 2 to configure CORS globally (e.g. enabled all request for development) you can do:

protected CorsConfigurationSource corsConfigurationSource() {
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    source.registerCorsConfiguration("/**", new CorsConfiguration().applyPermitDefaultValues());
    return source;

protected void configure(HttpSecurity http) throws Exception {

Consider defining a bean of type 'package' in your configuration [Spring-Boot]

I think, you are missing the @Bean annotation in your RequestController

Add the Bean in your file, this solved my issue
I got this solution while I was learning Spring Boot from tutorialspoint

private Applicant applicant;

public Applicant applicant() { 
    return new Applicant(); 

JWT authentication for ASP.NET Web API

I think you should use some 3d party server to support the JWT token and there is no out of the box JWT support in WEB API 2.

However there is an OWIN project for supporting some format of signed token (not JWT). It works as a reduced OAuth protocol to provide just a simple form of authentication for a web site.

You can read more about it e.g. here.

It's rather long, but most parts are details with controllers and ASP.NET Identity that you might not need at all. Most important are

Step 9: Add support for OAuth Bearer Tokens Generation

Step 12: Testing the Back-end API

There you can read how to set up endpoint (e.g. "/token") that you can access from frontend (and details on the format of the request).

Other steps provide details on how to connect that endpoint to the database, etc. and you can chose the parts that you require.

8080 port already taken issue when trying to redeploy project from Spring Tool Suite IDE

Goto Window->Preferences, search for Launching.

Select the "Terminate and Relaunch while launching" option.

Press Apply.

Error creating bean with name 'entityManagerFactory' defined in class path resource : Invocation of init method failed

The problem might be because of package conflicts. When you use @Id annotation in an entity, it might use the @Id of Spring framework; however, it must use @Id annotation of persistence API.

So use @javax.persistence.Id annotation in entities.

What are the main differences between JWT and OAuth authentication?

Jwt is a strict set of instructions for the issuing and validating of signed access tokens. The tokens contain claims that are used by an app to limit access to a user

OAuth2 on the other hand is not a protocol, its a delegated authorization framework. think very detailed guideline, for letting users and applications authorize specific permissions to other applications in both private and public settings. OpenID Connect which sits on top of OAUTH2 gives you Authentication and details how multiple different roles, users in your system, server side apps like an API, and clients such as websites or native mobile apps, can authenticate with each othe

Note oauth2 can work with jwt , flexible implementation, extandable to different applications

How to beautifully update a JPA entity in Spring Data?

Simple JPA update..

Customer customer = em.find(id, Customer.class); //Consider em as JPA EntityManager

Apache POI error loading XSSFWorkbook class

commons-collections4-x.x.jar definitely solve this problem but Apache has removed the Interface ListValuedMap from commons-Collections4-4.0.jar so use updated version 4.1 it has the required classes and Interfaces.

Refer here if you want to read Excel (2003 or 2007+) using java code.

How do you format code on save in VS Code

For eslint:

"editor.codeActionsOnSave": { "source.fixAll.eslint": true }

Correctly Parsing JSON in Swift 3

Swift 5 Cant fetch data from your api. Easiest way to parse json is Use Decodable protocol. Or Codable (Encodable & Decodable). For ex:

let json = """
    "dueDate": {
        "year": 2021,
        "month": 2,
        "day": 17

struct WrapperModel: Codable {
    var dueDate: DueDate

struct DueDate: Codable {
    var year: Int
    var month: Int
    var day: Int

let jsonData = Data(json.utf8)

let decoder = JSONDecoder()

do {
    let model = try decoder.decode(WrapperModel.self, from: jsonData)
} catch {

How can I change the user on Git Bash?

For any OS

This helped me so I'll put it here, just in case. Once you are done with adding the rsa keys for both the accounts, add a config file in your .ssh directory for both the accounts (.ssh/config)

# First account
   User git
   IdentityFile ~/.ssh/id_rsa_user1
# Second account
   User git
   IdentityFile ~/.ssh/id_rsa_user2

Make sure you use the correct usernames and RSA files. Next, you can open the terminal/git bash on the repository root and check which account you would be pushing from

git config

Suppose this returns the first user email and you want to push from the second user. Change the local and :

git config "SECOND_USER"
git config "[email protected]"

(This won't change the global config and you can have the first user set up as the global user). Once done, you can confirm with git config and it should return the email of the second user. You're all set to push to GitHub with the second user. The rest is all the same old git add , git commit and git push. To push from the first user, change the local again and follow the same steps. Hope it helps :)

If the above steps are still not working for you, check to see if you have uploaded the RSA keys within GitHub portal. Refer to GitHub documentation:

Then, clear your ssh cached keys Reference

ssh-add -D

Then add you 2 ssh keys

ssh-add ~/.ssh/id_rsa_user1
ssh-add ~/.ssh/id_rsa_user2

Then type in your terminal:

ssh -T [email protected]<SECOND_ACCOUNT_USERNAME_HERE>

You should see the following output:

Hi <SECOND_USERNAME>! You've successfully authenticated, but GitHub does not provide shell access.

Then, assign the correct remote to your local repository. Make sure you put the same username as the one you gave in your .ssh/config file next to Host. In the following case [email protected]<SECOND_ACCOUNT_USERNAME_HERE>.

git remote rm origin
git remote add origin [email protected]<SECOND_ACCOUNT_USERNAME_HERE>:/your_username/your_repository.git

ImportError: No module named google.protobuf

If you are a windows user and try to start py-script in cmd - don't forget to type python before filename.


I have "No module named google" error if forget to type it.

How do I get an OAuth 2.0 authentication token in C#

In Postman, click Generate Code and then in Generate Code Snippets dialog you can select a different coding language, including C# (RestSharp).

Also, you should only need the access token URL. The form parameters are then:


Code Snippet:

/* using RestSharp; // */

var client = new RestClient("");
var request = new RestRequest(Method.POST);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=client_credentials&client_id=abc&client_secret=123", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

From the response body you can then obtain your access token. For instance for a Bearer token type you can then add the following header to subsequent authenticated requests:

request.AddHeader("authorization", "Bearer <access_token>");

Spring Boot - Loading Initial Data

This will also work.

    CommandLineRunner init (StudentRepo studentRepo){
        return args -> {
            // Adding two students objects
            List<String> names = Arrays.asList("udara", "sampath");
            names.forEach(name -> Student(name)));

Could not load file or assembly 'CrystalDecisions.ReportAppServer.CommLayer, Version=13.0.2000.0

As I said in comment your crystaldecisions.reportappserver.commlayer.dll is not copied / present on your server. So for this you have to manually copy the dll and paste into you Bin folder

To copy a DLL from visual studio project follow the steps

1.Expand your Project's References hierarchy (Project should not be in debug mod)

2.Right Click on Particular Dll (in your case crystaldecisions.reportappserver.commlayer.dll) and select Properties and set 'Copy Local' attribute to TRUE

3 Build your project. The Dll should be there in your BIN Folder.

enter image description here

How to copy folders to docker image from Dockerfile?

Suppose you want to copy the contents from a folder where you have docker file into your container. Use ADD:

RUN mkdir /temp
ADD folder /temp/Newfolder  

it will add to your container with temp/newfolder

folder is the folder/directory where you have the dockerfile, more concretely, where you put your content and want to copy that.

Now can you check your copied/added folder by runining container and see the content using ls

How to configure Spring Security to allow Swagger URL to be accessed without authentication

I am using Spring Boot 5. I have this controller that I want an unauthenticated user to invoke.

  //Builds a form to send to devices   
@RequestMapping(value = "/{id}/ViewFormit", method = RequestMethod.GET)
String doFormIT(@PathVariable String id) {
        //Get a list of forms applicable to the current user
        FormService parent = new FormService();

Here is what i did in the configuuration.

   protected void configure(HttpSecurity http) throws Exception {

Hope this helps....

JPA Hibernate Persistence exception [PersistenceUnit: default] Unable to build Hibernate SessionFactory

The issue is that you are not able to get a connection to MYSQL database and hence it is throwing an error saying that cannot build a session factory.

Please see the error below:

 Caused by: java.sql.SQLException: Access denied for user ''@'localhost' (using password: NO) 

which points to username not getting populated.

Please recheck system properties


some packages seems to be missing as well pointing to a dependency issue:

package does not exist

Please run a mvn dependency:tree command to check for dependencies

How to write to a CSV line by line?

You could just write to the file as you would write any normal file.

with open('csvfile.csv','wb') as file:
    for l in text:

If just in case, it is a list of lists, you could directly use built-in csv module

import csv

with open("csvfile.csv", "wb") as file:
    writer = csv.writer(file)

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'demoRestController'

Your DemoApplication class is in the package and your LoginBean class is in the package. By default components (classes annotated with @Component) are found if they are in the same package or a sub-package of your main application class DemoApplication. This means that LoginBean isn't being found so dependency injection fails.

There are a couple of ways to solve your problem:

  1. Move LoginBean into or a sub-package.
  2. Configure the packages that are scanned for components using the scanBasePackages attribute of @SpringBootApplication that should be on DemoApplication.

A few of other things that aren't causing a problem, but are not quite right with the code you've posted:

  • @Service is a specialisation of @Component so you don't need both on LoginBean
  • Similarly, @RestController is a specialisation of @Component so you don't need both on DemoRestController
  • DemoRestController is an unusual place for @EnableAutoConfiguration. That annotation is typically found on your main application class (DemoApplication) either directly or via @SpringBootApplication which is a combination of @ComponentScan, @Configuration, and @EnableAutoConfiguration.

Android Studio - Failed to apply plugin [id '']

When I had this problem was beacuse my directory had non ASCII characteres. Try changing it

How to configure CORS in a Spring Boot + Spring Security application?

After much searching for the error coming from javascript CORS, the only elegant solution I found for this case was configuring the cors of Spring's own class org.springframework.web.cors.CorsConfiguration.CorsConfiguration()

public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    protected void configure(HttpSecurity http) throws Exception {
        http.cors().configurationSource(request -> new CorsConfiguration().applyPermitDefaultValues());

How to get response from S3 getObject in Node.js?

For someone looking for a NEST JS TYPESCRIPT version of the above:

     * to fetch a signed URL of a file
     * @param key key of the file to be fetched
     * @param bucket name of the bucket containing the file
    public getFileUrl(key: string, bucket?: string): Promise<string> {
        var scopeBucket: string = bucket ? bucket : this.defaultBucket;
        var params: any = {
            Bucket: scopeBucket,
            Key: key,
            Expires: signatureTimeout  // const value: 30
        return this.account.getSignedUrlPromise(getSignedUrlObject, params);

     * to get the downloadable file buffer of the file
     * @param key key of the file to be fetched
     * @param bucket name of the bucket containing the file
    public async getFileBuffer(key: string, bucket?: string): Promise<Buffer> {
        var scopeBucket: string = bucket ? bucket : this.defaultBucket;
        var params: GetObjectRequest = {
            Bucket: scopeBucket,
            Key: key
        var fileObject: GetObjectOutput = await this.account.getObject(params).promise();
        return Buffer.from(fileObject.Body.toString());

     * to upload a file stream onto AWS S3
     * @param stream file buffer to be uploaded
     * @param key key of the file to be uploaded
     * @param bucket name of the bucket 
    public async saveFile(file: Buffer, key: string, bucket?: string): Promise<any> {
        var scopeBucket: string = bucket ? bucket : this.defaultBucket;
        var params: any = {
            Body: file,
            Bucket: scopeBucket,
            Key: key,
            ACL: 'private'
        var uploaded: any = await this.account.upload(params).promise();
        if (uploaded && uploaded.Location && uploaded.Bucket === scopeBucket && uploaded.Key === key)
            return uploaded;
        else {
            throw new HttpException("Error occurred while uploading a file stream", HttpStatus.BAD_REQUEST);

Failed to load ApplicationContext (with annotation)

In my case, I had to do the following while running with Junit5

@SpringBootTest(classes = {abc.class}) @ExtendWith(SpringExtension.class

Here abc.class was the class that was being tested

What should I use to open a url instead of urlopen in urllib3

In urlip3 there's no .urlopen, instead try this:

import requests
html = requests.get(url)

disabling spring security in spring boot app

You could just comment the maven dependency for a while:

<!--        <dependency>

It worked fine for me

Disabling it from is deprecated for Spring Boot 2.0

Method List in Visual Studio Code

Invoke Code's Go to symbol command:

  • macOS: cmd+shift+o (the letter o, not zero)

  • Windows/Linux: ctrl+shift+o

Typing a colon (:) after invoking Go to symbol will group symbols by type (classes, interfaces, methods, properties, variables). Then just scroll to the methods section.

Could not autowire field:RestTemplate in Spring boot application

The simplest way I was able to achieve a similar feat to use the code below (reference), but I would suggest not to make API calls in controllers(SOLID principles). Also autowiring this way is better optimsed than the traditional way of doing it.

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

public class TestController {

    private final RestTemplate restTemplate;

    public TestController(RestTemplateBuilder builder) {
        this.restTemplate =;

    @RequestMapping(value="/micro/order/{id}", method= RequestMethod.GET, produces= MediaType.ALL_VALUE)
    public String placeOrder(@PathVariable("id") int customerId){

        System.out.println("Hit ===> PlaceOrder");

        Object[] customerJson = restTemplate.getForObject("http://localhost:8080/micro/customers", Object[].class);


        return "false";

Custom header to HttpClient request

I have found the answer to my question.


That should add a custom header to your request


On Debian 9 I had to:

$ sudo update-ca-certificates --fresh
$ export SSL_CERT_DIR=/etc/ssl/certs

I'm not sure why, but this enviroment variable was never set.

How, in general, does Node.js handle 10,000 concurrent requests?

Adding to slebetman's answer for more clarity on what happens while executing the code.

The internal thread pool in nodeJs just has 4 threads by default. and its not like the whole request is attached to a new thread from the thread pool the whole execution of request happens just like any normal request (without any blocking task) , just that whenever a request has any long running or a heavy operation like db call ,a file operation or a http request the task is queued to the internal thread pool which is provided by libuv. And as nodeJs provides 4 threads in internal thread pool by default every 5th or next concurrent request waits until a thread is free and once these operations are over the callback is pushed to the callback queue. and is picked up by event loop and sends back the response.

Now here comes another information that its not once single callback queue, there are many queues.

  1. NextTick queue
  2. Micro task queue
  3. Timers Queue
  4. IO callback queue (Requests, File ops, db ops)
  5. IO Poll queue
  6. Check Phase queue or SetImmediate
  7. close handlers queue

Whenever a request comes the code gets executing in this order of callbacks queued.

It is not like when there is a blocking request it is attached to a new thread. There are only 4 threads by default. So there is another queueing happening there.

Whenever in a code a blocking process like file read occurs , then calls a function which utilises thread from thread pool and then once the operation is done , the callback is passed to the respective queue and then executed in the order.

Everything gets queued based on the the type of callback and processed in the order mentioned above.

Spring Boot REST API - request timeout?

I feel like none of the answers really solve the issue. I think you need to tell the embedded server of Spring Boot what should be the maximum time to process a request. How exactly we do that is dependent on the type of the embedded server used.

In case of Undertow, one can do this:

class WebServerCustomizer : WebServerFactoryCustomizer<UndertowServletWebServerFactory> {
    override fun customize(factory: UndertowServletWebServerFactory) {
        factory.addBuilderCustomizers(UndertowBuilderCustomizer {
            it.setSocketOption(Options.READ_TIMEOUT, 5000)
            it.setSocketOption(Options.WRITE_TIMEOUT, 25000)

Spring Boot official doc:

How can I resolve the error "The security token included in the request is invalid" when running aws iam upload-server-certificate?

If you have been given a Session Token also, then you need to manually set it after configure:

aws configure set aws_session_token "<<your session token>>"

Spring Boot @autowired does not work, classes in different package

package com.test.springboot;
    @ComponentScan(basePackages = "com.test.springboot")
    public class SpringBoot1Application {

        public static void main(String[] args) {
            ApplicationContext context=, args);


package com.test.springboot;
    public class StudentController {
        private StudentDao studentDao;

        public String homePage() {
            return "home";

TypeError: a bytes-like object is required, not 'str' in python and CSV

just change wb to w




How to get bean using application context in spring boot

If you are inside of Spring bean (in this case @Controller bean) you shouldn't use Spring context instance at all. Just autowire className bean directly.

BTW, avoid using field injection as it's considered as bad practice.

How to restart kubernetes nodes?

If a node is so unhealthy that the master can't get status from it -- Kubernetes may not be able to restart the node. And if health checks aren't working, what hope do you have of accessing the node by SSH?

In this case, you may have to hard-reboot -- or, if your hardware is in the cloud, let your provider do it.

For example, the AWS EC2 Dashboard allows you to right-click an instance to pull up an "Instance State" menu -- from which you can reboot/terminate an unresponsive node.

Before doing this, you might choose to kubectl cordon node for good measure. And you may find kubectl delete node to be an important part of the process for getting things back to normal -- if the node doesn't automatically rejoin the cluster after a reboot.

Why would a node become unresponsive? Probably some resource has been exhausted in a way that prevents the host operating system from handling new requests in a timely manner. This could be disk, or network -- but the more insidious case is out-of-memory (OOM), which Linux handles poorly.

To help Kubernetes manage node memory safely, it's a good idea to do both of the following:

  • Reserve some memory for the system.
  • Be very careful with (avoid) opportunistic memory specifications for your pods. In other words, don't allow different values of requests and limits for memory.

The idea here is to avoid the complications associated with memory overcommit, because memory is incompressible, and both Linux and Kubernetes' OOM killers may not trigger before the node has already become unhealthy and unreachable.

Best HTTP Authorization header type for JWT

The best HTTP header for your client to send an access token (JWT or any other token) is the Authorization header with the Bearer authentication scheme.

This scheme is described by the RFC6750.


GET /resource HTTP/1.1
Authorization: Bearer eyJhbGciOiJIUzI1NiIXVCJ9TJV...r7E20RMHrHDcEfxjoYZgeFONFh7HgQ

If you need stronger security protection, you may also consider the following IETF draft: This draft seems to be a good alternative to the (abandoned?)

Note that even if this RFC and the above specifications are related to the OAuth2 Framework protocol, they can be used in any other contexts that require a token exchange between a client and a server.

Unlike the custom JWT scheme you mention in your question, the Bearer one is registered at the IANA.

Concerning the Basic and Digest authentication schemes, they are dedicated to authentication using a username and a secret (see RFC7616 and RFC7617) so not applicable in that context.

Spring boot - configure EntityManager

Hmmm you can find lot of examples for configuring spring framework. Anyways here is a sample

@ComponentScan(basePackageClasses = { 
    RepositoryMarker.class }
public class AppConfig {



@PropertySource(value = { "classpath:database/" })
public class PersistenceConfig {

    private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect";
    private static final String PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH = "hibernate.max_fetch_depth";
    private static final String PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE = "hibernate.jdbc.fetch_size";
    private static final String PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE = "hibernate.jdbc.batch_size";
    private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql";
    private static final String[] ENTITYMANAGER_PACKAGES_TO_SCAN = {"a.b.c.entities", "a.b.c.converters"};

    private Environment env;

     @Bean(destroyMethod = "close")
     public DataSource dataSource() {
         BasicDataSource dataSource = new BasicDataSource();
         return dataSource;

     public JpaTransactionManager jpaTransactionManager() {
         JpaTransactionManager transactionManager = new JpaTransactionManager();
         return transactionManager;

    private HibernateJpaVendorAdapter vendorAdaptor() {
         HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
         return vendorAdapter;

    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() {

         LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();

         return entityManagerFactoryBean;

     private Properties jpaHibernateProperties() {

         Properties properties = new Properties();


         properties.put(AvailableSettings.SCHEMA_GEN_DATABASE_ACTION, "none");
         properties.put(AvailableSettings.USE_CLASS_ENHANCER, "false");      
         return properties;       



public static void main(String[] args) { 
    try (GenericApplicationContext springContext = new AnnotationConfigApplicationContext(AppConfig.class)) {
        MyService myService = springContext.getBean(MyServiceImpl.class);
        try {
            myService.handleProcess(fromDate, toDate);
        } catch (Exception e) {
            logger.error("Exception occurs", e);
            myService.handleException(fromDate, toDate, e);
    } catch (Exception e) {
        logger.error("Exception occurs in loading Spring context: ", e);


public class MyServiceImpl implements MyService {

    private MyDao myDao;

    public void handleProcess(String fromDate, String toDate) {
        List<Student> myList =, toDate);


public class MyDaoImpl implements MyDao {

    private EntityManager entityManager;

    public Student select(String fromDate, String toDate){

        TypedQuery<Student> query = entityManager.createNamedQuery("Student.findByKey", Student.class);
        query.setParameter("fromDate", fromDate);
        query.setParameter("toDate", toDate);
        List<Student> list = query.getResultList();
        return CollectionUtils.isEmpty(list) ? null : list;


Assuming maven project: Properties file should be in src/main/resources/database folder file

jdbc.url=your db url
jdbc.username=your Username
jdbc.password=Your password

hibernate.max_fetch_depth = 3
hibernate.jdbc.fetch_size = 50
hibernate.jdbc.batch_size = 10
hibernate.show_sql = true

ServiceMarker and RepositoryMarker are just empty interfaces in your service or repository impl package.

Let's say you have package name a.b.c.service.impl. MyServiceImpl is in this package and so is ServiceMarker.

public interface ServiceMarker {


Same for repository marker. Let's say you have a.b.c.repository.impl or a.b.c.dao.impl package name. Then MyDaoImpl is in this this package and also Repositorymarker

public interface RepositoryMarker {



//dummy class and dummy query
@NamedQuery(name="Student.findByKey", query="select s from Student s where s.fromDate=:fromDate" and s.toDate = :toDate)
public class Student implements Serializable {

    private LocalDateTime fromDate;
    private LocalDateTime toDate;

    //getters setters



@Converter(autoApply = true)
public class LocalDateTimeConverter implements AttributeConverter<LocalDateTime, Timestamp> {

    public Timestamp convertToDatabaseColumn(LocalDateTime dateTime) {

        if (dateTime == null) {
            return null;
        return Timestamp.valueOf(dateTime);

    public LocalDateTime convertToEntityAttribute(Timestamp timestamp) {

        if (timestamp == null) {
            return null;
        return timestamp.toLocalDateTime();




    <!-- Spring -->









Hope it helps. Thanks

Spring jUnit Testing properties file

I faced the same issue, spent too much calories searching for the right fix until I decided to settle down with file reading:

Properties configProps = new Properties();
InputStream iStream = new ClassPathResource("").getInputStream();
InputStream iStream = getConfigFile();

HikariCP - connection is not available

I managed to fix it finally. The problem is not related to HikariCP. The problem persisted because of some complex methods in REST controllers executing multiple changes in DB through JPA repositories. For some reasons calls to these interfaces resulted in a growing number of "freezed" active connections, exhausting the pool. Either annotating these methods as @Transactional or enveloping all the logic in a single call to transactional service method seem to solve the problem.

Ubuntu: OpenJDK 8 - Unable to locate package

As you can see I only have java 1.7 installed (on a Ubuntu 14.04 machine).

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64

To install Java 8, I did,

sudo add-apt-repository ppa:openjdk-r/ppa
sudo apt-get update
sudo apt-get install openjdk-8-jdk

Afterwards, now I have java 7 and 8,

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64
java-1.8.0-openjdk-amd64 1069 /usr/lib/jvm/java-1.8.0-openjdk-amd64

BONUS ADDED (how to switch between different versions)

  • run the follwing command from the terminal:

sudo update-alternatives --config java

There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
  0            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      auto mode
  1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      manual mode
* 2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1069      manual mode

Press enter to keep the current choice[*], or type selection number:

As you can see I'm running open jdk 8. To switch to to jdk 7, press 1 and hit the Enter key. Do the same for javac as well with, sudo update-alternatives --config javac.

Check versions to confirm the change: java -version and javac -version.

How can I represent 'Authorization: Bearer <token>' in a Swagger Spec (swagger.json)

Posting 2021 answer in JSON using openapi 3.0.0:

  "openapi": "3.0.0",
  "servers": [
      "url": "/"
  "paths": {
    "/skills": {
      "put": {
        "security": [
              "bearerAuth": []

  "components": {        
    "securitySchemes": {
      "bearerAuth": {
        "type": "http",
        "scheme": "bearer",
        "bearerFormat": "JWT"

java.lang.IllegalStateException: Error processing condition on org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration

I had the same its because of version incompatibility check for version or remove version if using spring boot

How to Get JSON Array Within JSON Object?

I guess this will help you.

JSONObject jsonObj = new JSONObject(jsonStr);

JSONArray ja_data = jsonObj.getJSONArray("data");
int length = jsonObj.length();
for(int i=0; i<length; i++) {
  JSONObject jsonObj = ja_data.getJSONObject(i);
  Toast.makeText(this, jsonObj.getString("Name"), Toast.LENGTH_LONG).show();

  // getting inner array Ingredients
  JSONArray ja = jsonObj.getJSONArray("Ingredients");
  int len = ja.length();

  ArrayList<String> Ingredients_names = new ArrayList<>();
  for(int j=0; j<len; j++) {
    JSONObject json = ja.getJSONObject(j);

toBe(true) vs toBeTruthy() vs toBeTrue()

In javascript there are trues and truthys. When something is true it is obviously true or false. When something is truthy it may or may not be a boolean, but the "cast" value of is a boolean.


true == true; // (true) true
1 == true; // (true) truthy
"hello" == true;  // (true) truthy
[1, 2, 3] == true; // (true) truthy
[] == false; // (true) truthy
false == false; // (true) true
0 == false; // (true) truthy
"" == false; // (true) truthy
undefined == false; // (true) truthy
null == false; // (true) truthy

This can make things simpler if you want to check if a string is set or an array has any values.

var users = [];

if(users) {
  // this array is populated. do something with the array

var name = "";

if(!name) {
  // you forgot to enter your name!

And as stated. expect(something).toBe(true) and expect(something).toBeTrue() is the same. But expect(something).toBeTruthy() is not the same as either of those.

Mapping list in Yaml to list of objects in Spring Boot

The reason must be somewhere else. Using only Spring Boot 1.2.2 out of the box with no configuration, it Just Works. Have a look at this repo - can you get it to break?

Are you sure the YAML file looks exactly the way you pasted? No extra whitespace, characters, special characters, mis-indentation or something of that sort? Is it possible you have another file elsewhere in the search path that is used instead of the one you're expecting?

WARNING: Exception encountered during context initialization - cancelling refresh attempt

I was having the problem as a beginner..........

There was issue in the path of the xml file I have saved.

Spring - No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call

I had the same problem and I added tx:annotation-driven in applicationContext.xml and it worked.

How to find distinct rows with field in list using JPA and Spring?

@Query("SELECT DISTINCT name FROM people WHERE name NOT IN (:names)")
List<String> findNonReferencedNames(@Param("names") List<String> names);

Using Postman to access OAuth 2.0 Google APIs

The current answer is outdated. Here's the up-to-date flow:

The approach outlined here still works (10.12.2020) as confirmed by alexwhan.

We will use the YouTube Data API for our example. Make changes accordingly.

Make sure you have enabled your desired API for your project.

Create the OAuth 2.0 Client

  1. Visit
  3. Select OAuth client ID
  4. For Application Type choose Web Application
  5. Add a name
  6. Add following URI for Authorized redirect URIs
  1. Click Save
  2. Click on the OAuth client you just generated
  3. In the Topbar click on DOWNLOAD JSON and save the file somewhere on your machine.

We will use the file later to authenticate Postman.

Authorize Postman via OAuth 2.0 Client

  1. In the Auth tab under TYPE choose OAuth 2.0
  2. For Access Token enter the Access Token found inside the client_secret_[YourClientID].json file we downloaded in step 9
  3. Click on Get New Access Token
  4. Make sure your settings are as follows:

Click here to see the settings

You can find everything else you need in your .json file.

  1. Click on Request Token
  2. A new browser tab/window will open
  3. Once the browser tab opens, login via the appropriate Google account
  4. Accept the consent screen
  5. Done

Ignore the browser message "Not safe" etc. This will be shown until your app has been screened by Google officials. In this case it will always be shown since Postman is the app.

Error resolving template "index", template might not exist or might not be accessible by any of the configured Template Resolvers

It May be due to some exceptions like (Parsing NUMERIC to String or vise versa).

Please verify cell values either are null or do handle Exception and see.

Best, Shahid

pip install failing with: OSError: [Errno 13] Permission denied on directory

User doesn't have write permission for some Python installation paths. You can give the permission by:

sudo chown -R $USER /absolute/path/to/directory

So you should give permission, then try to install it again, if you have new paths you should also give permission:

sudo chown -R $USER /usr/local/lib/python2.7/

Spring Boot: Cannot access REST Controller on localhost (404)

For me, the problem was that I had set up the Application in a way that it always immediately shut down after starting. So by the time I tried out if I could access the controller, the Application wasn't running anymore. The problem with immediately shutting down is adressed in this thread.

Any way (or shortcut) to auto import the classes in IntelliJ IDEA like in Eclipse?

Use control+option+O to auto-import the package or auto remove unused packages on MacOS

How to set the title text color of UIButton?

referring to radio buttons ,you can also do it with Segmented Control as following:

step 1: drag a segmented control to your view in the attribute inspector change the title of the two segments ,for example "Male" and "Female"

step 2: create an outlet & an action for it in the code

step 3: create a variable for future use to contain choice's data

in the code do as following:

@IBOutlet weak var genderSeg: UISegmentedControl!

var genderPick : String = ""

 @IBAction func segAction(_ sender: Any) {

    if genderSeg.selectedSegmentIndex == 0 {
         genderPick = "Male"
    } else if genderSeg.selectedSegmentIndex == 1 {
        genderPick = "Female"

I'm getting favicon.ico error

Also, be careful so your href location isn't faulty. Study case:

My index page was in a temporary sub-folder named LAYOUTS. To reach the favicon.png from inside the IMAGES folder, which was a sibling of the LAYOUTS folder, I had to put a path in my href like this


Double periods are necessary for folder navigation "upwards", then the forward slash + images string gets you into the images folder (performing a tree branch "jump") and finally you get to reference your file by writing favicon-32x32.png.

This explanation is useful for those that start out from scratch and it would have been useful to have seen it a couple of times since I would forget that I had certain *.php files outside the LAYOUTS folder which needed different tree hrefs on my links, from the HEAD section of each page.

Reference the path to your favicon image accordingly.

How do I enable logging for Spring Security?

You can easily enable debugging support using an option for the @EnableWebSecurity annotation:

@EnableWebSecurity(debug = true)
public class SecurityConfiguration extends WebSecurityConfigurerAdapter {

If you need profile-specific control the in your application-{profile}.properties file

Get Detailed Post:

Spring MVC 4: "application/json" Content Type is not being set correctly

As other people have commented, because the return type of your method is String Spring won't feel need to do anything with the result.

If you change your signature so that the return type is something that needs marshalling, that should help:

@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
public Map<String, Object> bar() {
    HashMap<String, Object> map = new HashMap<String, Object>();
    map.put("test", "jsonRestExample");
    return map;

Correct way to set Bearer token with CURL

If you are working with a private token instead (like Gitlab API), you should replace:

$authorization = "Authorization: Bearer 080042cad6356ad5dc0a720c18b53b8e53d4c274"


$authorization = "PRIVATE-TOKEN 080042cad6356ad5dc0a720c18b53b8e53d4c274";

Using an authorization header with Fetch in React Native

It turns out, I was using the fetch method incorrectly.

fetch expects two parameters: an endpoint to the API, and an optional object which can contain body and headers.

I was wrapping the intended object within a second object, which did not get me any desired result.

Here's how it looks on a high level:

  .then(function(res) {
    return res.json();
  .then(function(resJson) {
    return resJson;

I structured my object as such:

var obj = {  
  method: 'POST',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    'Origin': '',
    'Host': ''
  body: JSON.stringify({
    'client_id': '(API KEY)',
    'client_secret': '(API SECRET)',
    'grant_type': 'client_credentials'

How do you format code in Visual Studio Code (VSCode)

  1. Right click somewhere in the content area (text) for the file
  2. Select Format Document from the menu:
    • Windows: Alt Shift F
    • Linux: Alt Shift I
    • macOS: ? ? F

Enter image description here

Making an API call in Python with an API that requires a bearer token

Here is full example of implementation in cURL and in Python - for authorization and for making API calls


1. Authorization

You have received access data like this:

Username: johndoe

Password: zznAQOoWyj8uuAgq

Consumer Key: ggczWttBWlTjXCEtk3Yie_WJGEIa

Consumer Secret: uuzPjjJykiuuLfHkfgSdXLV98Ciga

Which you can call in cURL like this:

curl -k -d "grant_type=password&username=Username&password=Password" \

                    -H "Authorization: Basic Base64(consumer-key:consumer-secret)" \


or for this case it would be:

curl -k -d "grant_type=password&username=johndoe&password=zznAQOoWyj8uuAgq" \

                    -H "Authorization: Basic zzRjettzNUJXbFRqWENuuGszWWllX1iiR0VJYTpRelBLZkp5a2l2V0xmSGtmZ1NkWExWzzhDaWdh" \


Answer would be something like:

    "access_token": "zz8d62zz-56zz-34zz-9zzf-azze1b8057f8",
    "refresh_token": "zzazz4c3-zz2e-zz25-zz97-ezz6e219cbf6",
    "scope": "default",
    "token_type": "Bearer",
    "expires_in": 3600

2. Calling API

Here is how you call some API that uses authentication from above. Limit and offset are just examples of 2 parameters that API could implement. You need access_token from above inserted after "Bearer ".So here is how you call some API with authentication data from above:

curl -k -X GET "" -H "accept: application/json" -H "Authorization: Bearer zz8d62zz-56zz-34zz-9zzf-azze1b8057f8"


Same thing from above implemented in Python. I've put text in comments so code could be copy-pasted.

# Authorization data

import base64
import requests

username = 'johndoe'
password= 'zznAQOoWyj8uuAgq'
consumer_key = 'ggczWttBWlTjXCEtk3Yie_WJGEIa'
consumer_secret = 'uuzPjjJykiuuLfHkfgSdXLV98Ciga'
consumer_key_secret = consumer_key+":"+consumer_secret
consumer_key_secret_enc = base64.b64encode(consumer_key_secret.encode()).decode()

# Your decoded key will be something like:

headersAuth = {
    'Authorization': 'Basic '+ str(consumer_key_secret_enc),

data = {
  'grant_type': 'password',
  'username': username,
  'password': password

## Authentication request

response ='', headers=headersAuth, data=data, verify=True)
j = response.json()

# When you print that response you will get dictionary like this:

        "access_token": "zz8d62zz-56zz-34zz-9zzf-azze1b8057f8",
        "refresh_token": "zzazz4c3-zz2e-zz25-zz97-ezz6e219cbf6",
        "scope": "default",
        "token_type": "Bearer",
        "expires_in": 3600

# You have to use `access_token` in API calls explained bellow.
# You can get `access_token` with j['access_token'].

# Using authentication to make API calls   

## Define header for making API calls that will hold authentication data

headersAPI = {
    'accept': 'application/json',
    'Authorization': 'Bearer '+j['access_token'],

### Usage of parameters defined in your API
params = (
    ('offset', '0'),
    ('limit', '20'),

# Making sample API call with authentication and API parameters data

response = requests.get('', headers=headersAPI, params=params, verify=True)
api_response = response.json()

How to get local server host and port in Spring Boot?

You can get hostname from spring cloud property in spring-cloud-commons-2.1.0.RC2.jar


spring.factories of spring-cloud-commons-2.1.0.RC2.jar


UnsatisfiedDependencyException: Error creating bean with name 'entityManagerFactory'

The MySQL dependency should be like the following syntax in the pom.xml file.


Make sure the syntax, groupId, artifactId, Version has included in the dependancy.

Getting "error": "unsupported_grant_type" when trying to get a JWT by calling an OWIN OAuth secured Web Api via Postman

With Postman, select Body tab and choose the raw option and type the following:


Required request body content is missing: org.springframework.web.method.HandlerMethod$HandlerMethodParameter

You shouldn't send a request body with an HTTP GET request. You should modify addDepartment() so that it only supports POST, and POST your JSON to that endpoint. If you want to GET information about a department, you should create a separate controller method that does that (and does not require a request body).

Also, double-check your endpoint definitions since you have misspelled "reimbursement" in the $.ajax call.

Can't Autowire @Repository annotated interface in Spring Boot

It seems your @ComponentScan annotation is not set properly. Try :

@ComponentScan(basePackages = {""})

Actually you do not need the component scan if you have your main class at the top of the structure, for example directly under package.

Also, you don't need both


The @SpringBootApplication annotation includes @EnableAutoConfiguration by default.

InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately

If you are not able to upgrade your Python version to 2.7.9, and want to suppress warnings,

you can downgrade your 'requests' version to 2.5.3:

pip install requests==2.5.3

Bugfix disclosure / Warning introduced in 2.6.0

changing kafka retention period during runtime

The following is the right way to alter topic config as of Kafka

bin/ --zookeeper <zk_host> --alter --entity-type topics --entity-name test_topic --add-config

Topic config alter operations have been deprecated for bin/

WARNING: Altering topic configuration from this script has been deprecated and may be removed in future releases.
     Going forward, please use for this functionality`

Convert a object into JSON in REST service by Spring MVC

Spring framework itself handles json conversion when controller is annotated properly.

For eg:

   @PutMapping(produces = {"application/json"})
        public UpdateResponse someMethod(){ //do something
return UpdateResponseInstance;

Here spring internally converts the UpdateResponse object to corresponding json string and returns it. In order to do it spring internally uses Jackson library.

If you require a json representation of a model object anywhere apart from controller then you can use objectMapper provided by jackson. Model should be properly annotated for this to work.


ObjectMapper mapper = new ObjectMapper();
SomeModelClass someModelObject = someModelRepository.findById(idValue).get();

Cannot find java. Please use the --jdkhome switch

Try Java SE Runtime Environment 8. It fixed it for me.

Netbeans 8.0.2 The module has not been deployed

Maybe because you may need to create Db Resource and Pool manually on the Glassfish server like this,

In Netbeans -> Projects, Open Server Resources -> glassfish-resources.xml We have to create JDBC Resource and JDBC Connection Pool Manually on Glassfish. I am using my values here, don't use them, see your .xml !

Value of jndi-name is your JDBC Resource and Value of pool-name is your JDBC Connection Pool.

Open Browser for Glassfish Admin, https://localhost:4848/

Go to, JDBC Connection Pool -> New: 1) Pool Name: mysql_customersdb_rootPool 2) Resource Type: javax.sql.ConnectionPoolDataSource 3) Database Driver Vendor: MySql

Press Next,

URL: jdbc:mysql://localhost:3306/customersdb?zeroDateTimeBehavior=convertToNull Url: jdbc:mysql://localhost:3306/customersdb?zeroDateTimeBehavior=convertToNull User: root Password: root

JDBC Resources -> New

JNDI Name: CustomersDS Pool Name: mysql_customersdb_rootPool

Press Ok.

Right Click your Project and Press Run :)

Spring boot - Not a managed type

I had this same problem but only when running spring boot tests cases that required JPA. The end result was that our own jpa test configuration was initializing an EntityManagerFactory and setting the packages to scan. This evidently will override the EntityScan parameters if you are setting it manually.

    final LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
    factory.setJpaVendorAdapter( vendorAdapter );
    factory.setPackagesToScan( Project.class.getPackage().getName());
    factory.setDataSource( dataSource );

Important to note: if you are still stuck you should set a break point in the org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager on the setPackagesToScan() method and take a look at where this is being called and what packages are being passed to it.

@Autowired - No qualifying bean of type found for dependency at least 1 bean

Guys I found the issue

I just tried by adding the qualifier name in employee service finally it solved my issue.


public class EmployeeServiceImpl implements EmployeeService{


"Could not find acceptable representation" using spring-boot-starter-web

I had this issue when accessing actuator. Putting following configuration class solved the issue:

public class MediaConverterConfiguration implements WebMvcConfigurer {
    public MappingJackson2HttpMessageConverter jacksonConverter() {
        MappingJackson2HttpMessageConverter mc =
                new MappingJackson2HttpMessageConverter();
        List<MediaType> supportedMediaTypes =
                new ArrayList<>(mc.getSupportedMediaTypes());
        return mc;

    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {

How to change default Anaconda python environment

The correct answer (as of Dec 2018) is... you can't. Upgrading conda install python=3.6 may work, but it might not if you have packages that are necessary, but cannot be uninstalled.

Anaconda uses a default environment named base and you cannot create a new (e.g. python 3.6) environment with the same name. This is intentional. If you want your base Anaconda to be python 3.6, the right way to do this is to install Anaconda for python 3.6. As a package manager, the goal of Anaconda is to make different environments encapsulated, hence why you must source activate into them and why you can't just quietly switch the base package at will as this could lead to many issues on production systems.

Open web in new tab Selenium + Python


Where browser is the webDriver

How to determine programmatically the current active profile using Spring boot

It doesn't matter is your app Boot or just raw Spring. There is just enough to inject org.springframework.core.env.Environment to your bean.

private Environment environment;


How to customise the Jackson JSON mapper implicitly used by Spring Boot?

The right way to add further configurations to the Spring Boot peconfigured ObjectMapper is to define a Jackson2ObjectMapperBuilderCustomizer. Else you are overwriting Springs configuration, which you do not want to lose.

public class MyJacksonConfigurer implements Jackson2ObjectMapperBuilderCustomizer {
    public void customize(Jackson2ObjectMapperBuilder builder) {
        builder.deserializerByType(LocalDate.class, new MyOwnJsonLocalDateTimeDeserializer());

Spring Could not Resolve placeholder

Hopefully it will be still helpful, the (or application.yml) file must be in both the paths:

  • src/main/resource/config
  • src/test/resource/config

containing the same property you are referring

Spring Boot - Error creating bean with name 'dataSource' defined in class path resource

It worked for me you can try your: Add this to VM options in Tomcat


How to autowire RestTemplate using annotations

You can add the method below to your class for providing a default implementation of RestTemplate:

public RestTemplate restTemplate() {
    return new RestTemplate();

How to use Spring Boot with MySQL database and JPA?

In the spring boot reference,it said:

When a class doesn’t include a package declaration it is considered to be in the “default package”. The use of the “default package” is generally discouraged, and should be avoided. It can cause particular problems for Spring Boot applications that use @ComponentScan, @EntityScan or @SpringBootApplication annotations, since every class from every jar, will be read.

 +- example
     +- myproject
         +- domain
         |   +-
         |   +-
         +- service
         |   +-
         +- web

In your cases. You must add scanBasePackages in the @SpringBootApplication annotation.just like@SpringBootApplication(scanBasePackages={"domain","contorller"..})

Can not deserialize instance of java.lang.String out of START_ARRAY token

The error is:

Can not deserialize instance of java.lang.String out of START_ARRAY token at [Source: line: 1, column: 1095] (through reference chain: JsonGen["platforms"])

In JSON, platforms look like this:

"platforms": [
        "platform": "iphone"
        "platform": "ipad"
        "platform": "android_phone"
        "platform": "android_tablet"

So try change your pojo to something like this:

private List platforms;

public List getPlatforms(){
    return this.platforms;

public void setPlatforms(List platforms){
    this.platforms = platforms;

EDIT: you will need change mobile_networks too. Will look like this:

private List mobile_networks;

public List getMobile_networks() {
    return mobile_networks;

public void setMobile_networks(List mobile_networks) {
    this.mobile_networks = mobile_networks;

Spring Boot Multiple Datasource

once you start work with jpa and some driver is in your class path spring boot right away puts it inside as your data source (e.g h2 ) for using the defult data source therefore u will need only to define

spring.datasource.url= jdbc:mysql://localhost:3306/

if we go one step farther and u want to use two I would reccomend to use two data sources such as explained here : Spring Boot Configure and Use Two DataSources

UnicodeEncodeError: 'charmap' codec can't encode characters


You may or may not need to set that second environment variable PYTHONLEGACYWINDOWSSTDIO.

Alternatively, this can be done in code (although it seems that doing it through env vars is recommended):


Additionally: Reproducing this error was a bit of a pain, so leaving this here too in case you need to reproduce it on your machine:

set PYTHONIOENCODING=windows-1252

Multipart File Upload Using Spring Rest Template + Spring Web MVC

For those who are getting the error as:

I/O error on POST request for "anothermachine:31112/url/path";: class path 
resource [fileName.csv] cannot be resolved to URL because it does not exist.

It can be resolved by using the

LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
map.add("file", new FileSystemResource(file));

If the file is not present in the classpath, and an absolute path is required.

intellij incorrectly saying no beans of type found for autowired repository

My solution to this issue in my spring boot application was to open the spring application context and adding the class for the missing autowired bean manually!

(access via Project Structure menu or spring tool window... edit "Spring Application Context")

So instead of SpringApplicationContext just containing my ExampleApplication spring configuration it also contains the missing Bean:



et voilà: The error message disappeared!

Show DataFrame as table in iPython Notebook

This answer is based on the 2nd tip from this blog post: 28 Jupyter Notebook tips, tricks and shortcuts

You can add the following code to the top of your notebook

from IPython.core.interactiveshell import InteractiveShell
InteractiveShell.ast_node_interactivity = "all"

This tells Jupyter to print the results for any variable or statement on it’s own line. So you can then execute a cell solely containing


and it will "print out the beautiful tables for both datasets".

Spring AMQP + RabbitMQ 3.3.5 ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN

The error

ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN. For details see the broker logfile.

can occur if the credentials that your application is trying to use to connect to RabbitMQ are incorrect or missing.

I had this happen when the RabbitMQ credentials stored in my ASP.NET application's web.config file had a value of "" for the password instead of the actual password string value.

How to filter an array of objects based on values in an inner array with jq?

Here is another solution which uses any/2

map(select(any(.Names[]; contains("data"))|not)|.Id)[]

with the sample data and the -r option it produces


org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set

I also had this problem. In my case it was because of no grants were assigned to MySQL user. Assigning grants to MySQL user which my app uses resolved the issue:

grant select, insert, delete, update on my_db.* to 'my_user'@'%';

Error starting Tomcat from NetBeans - '*' is not recognized as an internal or external command

I didnt try Sumama Waheed's answer but what worked for me was replacing the bin/catalina.jar with a working jar (I disposed of an older tomcat) and after adding in NetBeans, I put the original catalina.jar again.

How can I analyze a heap dump in IntelliJ? (memory leak)

There also exists a 'JVM Debugger Memory View' found in the plugin repository, which could be useful.

Spring Boot, Spring Data JPA with multiple DataSources

here is my solution. base on spring-boot.1.2.5.RELEASE.

first.datasource.validation-query=select 1

second.datasource.validation-query=select 1

public class DataSourceConfig {
    public DataSource firstDataSource() {
        DataSource ds =  DataSourceBuilder.create().build();
        return ds;

    public DataSource secondDataSource() {
        DataSource ds =  DataSourceBuilder.create().build();
        return ds;

How to include js and CSS in JSP with spring MVC

you need declare resources in dispatcher servelet file.below is two declarations

<mvc:annotation-driven />
<mvc:resources location="/resources/" mapping="/resources/**" />

Spring Hibernate - Could not obtain transaction-synchronized Session for current thread

My configuration was like this. I had a QuartzJob , a Service Bean , and Dao . as usual it was configured with LocalSessionFactoryBean (for hibernate) , and SchedulerFactoryBean for Quartz framework. while writing the Quartz job , I by mistake annotated it with @Service , I should not have done that because I was using another strategy to wire the QuartzBean using AutowiringSpringBeanJobFactory extending SpringBeanJobFactory.

So what actually was happening is that due to Quartz Autowire , TX was getting injected to the Job Bean and at the same time Tx Context was set by virtue of @Service annotation and hence the TX was falling out of sync !!

I hope it help to those for whom above solutions really didn't solved the issue. I was using Spring 4.2.5 and Hibernate 4.0.1 ,

I see that in this thread there is a unnecessary suggestion to add @Transactional annotation to the DAO(@Repository) , that is a useless suggestion cause @Repository has all what it needs to have don't have to specially set that @transactional on DAOs , as the DAOs are called from the services which have already being injected by @Trasancational . I hope this might be helpful people who are using Quartz , Spring and Hibernate together.

I have filtered my Excel data and now I want to number the rows. How do I do that?

Try this function:

=SUBTOTAL(3, B$2:B2)

You can find more details in this blog entry.

No found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations:

Look at the exception:

No qualifying bean of type [] found for dependency

This means that there's no bean available to fulfill that dependency. Yes, you have an implementation of the interface, but you haven't created a bean for that implementation. You have two options:

  • Annotate UserDaoImpl with @Component or @Repository, and let the component scan do the work for you, exactly as you have done with UserService.
  • Add the bean manually to your xml file, the same you have done with UserBoImpl.

Remember that if you create the bean explicitly you need to put the definition before the component scan. In this case the order is important.

Cannot start GlassFish 4.1 from within Netbeans 8.0.1 Service area

Yes you can solve this error by changing the port number of glassfish because the WAMP SERVER or ORACLE database software uses a port number 8080, so there is a conflict of port number.

1)open a path like C:\GlassFish_Server\glassfish\domains\domain1\config\domain.xml.

2)find out the 8080 port number with the help of ctrl+F. You will get the following code...

<network-listener protocol="http-listener-1" port="8080" name="http-listener-1" thread-pool="http-thread-pool" transport="tcp">

3) Change that port number from 8080 to 9090 or 1234 or whatever you like..

4) Save it. Open a Netbeans IDE goto the glassfish server .

5) Right click on the server -> select refresh option.

6) to check the port no. which is given by u just right click on the server-> property.

7) Start the Glassfish server . Yehhh the error is gone...

Difference between Amazon EC2 and AWS Elastic Beanstalk

First off, EC2 and Elastic Compute Cloud are the same thing.

Next, AWS encompasses the range of Web Services that includes EC2 and Elastic Beanstalk. It also includes many others such as S3, RDS, DynamoDB, and all the others.


EC2 is Amazon's service that allows you to create a server (AWS calls these instances) in the AWS cloud. You pay by the hour and only what you use. You can do whatever you want with this instance as well as launch n number of instances.

Elastic Beanstalk

Elastic Beanstalk is one layer of abstraction away from the EC2 layer. Elastic Beanstalk will setup an "environment" for you that can contain a number of EC2 instances, an optional database, as well as a few other AWS components such as a Elastic Load Balancer, Auto-Scaling Group, Security Group. Then Elastic Beanstalk will manage these items for you whenever you want to update your software running in AWS. Elastic Beanstalk doesn't add any cost on top of these resources that it creates for you. If you have 10 hours of EC2 usage, then all you pay is 10 compute hours.

Running Wordpress

For running Wordpress, it is whatever you are most comfortable with. You could run it straight on a single EC2 instance, you could use a solution from the AWS Marketplace, or you could use Elastic Beanstalk.

What to pick?

In the case that you want to reduce system operations and just focus on the website, then Elastic Beanstalk would be the best choice for that. Elastic Beanstalk supports a PHP stack (as well as others). You can keep your site in version control and easily deploy to your environment whenever you make changes. It will also setup an Autoscaling group which can spawn up more EC2 instances if traffic is growing.

Here's the first result off of Google when searching for "elastic beanstalk wordpress":

80-characters / right margin line in Sublime Text 3

Yes, it is possible both in Sublime Text 2 and 3 (which you should really upgrade to if you haven't already). Select View ? Ruler ? 80 (there are several other options there as well). If you like to actually wrap your text at 80 columns, select View ? Word Wrap Column ? 80. Make sure that View ? Word Wrap is selected.

To make your selections permanent (the default for all opened files or views), open Preferences ? Settings—User and use any of the following rules:

    // set vertical rulers in specified columns.
    // Use "rulers": [80] for just one ruler
    // default value is []
    "rulers": [80, 100, 120],

    // turn on word wrap for source and text
    // default value is "auto", which means off for source and on for text
    "word_wrap": true,

    // set word wrapping at this column
    // default value is 0, meaning wrapping occurs at window width
    "wrap_width": 80

These settings can also be used in a .sublime-project file to set defaults on a per-project basis, or in a syntax-specific .sublime-settings file if you only want them to apply to files written in a certain language (Python.sublime-settings vs. JavaScript.sublime-settings, for example). Access these settings files by opening a file with the desired syntax, then selecting Preferences ? Settings—More ? Syntax Specific—User.

As always, if you have multiple entries in your settings file, separate them with commas , except for after the last one. The entire content should be enclosed in curly braces { }. Basically, make sure it's valid JSON.

If you'd like a key combo to automatically set the ruler at 80 for a particular view/file, or you are interested in learning how to set the value without using the mouse, please see my answer here.

Finally, as mentioned in another answer, you really should be using a monospace font in order for your code to line up correctly. Other types of fonts have variable-width letters, which means one 80-character line may not appear to be the same length as another 80-character line with different content, and your indentations will look all messed up. Sublime has monospace fonts set by default, but you can of course choose any one you want. Personally, I really like Liberation Mono. It has glyphs to support many different languages and Unicode characters, looks good at a variety of different sizes, and (most importantly for a programming font) clearly differentiates between 0 and O (digit zero and capital letter oh) and 1 and l (digit one and lowercase letter ell), which not all monospace fonts do, unfortunately. Version 2.0 and later of the font are licensed under the open-source SIL Open Font License 1.1 (here is the FAQ).

Classpath resource not found when running as jar

I encountered this limitation too and created this library to overcome the issue: spring-boot-jar-resources It basically allows you to register a custom ResourceLoader with Spring Boot that extracts the classpath resources from the JAR as needed, transparently.

What is the OAuth 2.0 Bearer Token exactly?

Bearer token is one or more repetition of alphabet, digit, "-" , "." , "_" , "~" , "+" , "/" followed by 0 or more "=".

RFC 6750 2.1. Authorization Request Header Field (Format is ABNF (Augmented BNF))

The syntax for Bearer credentials is as follows:

     b64token    = 1*( ALPHA / DIGIT /
                       "-" / "." / "_" / "~" / "+" / "/" ) *"="
     credentials = "Bearer" 1*SP b64token

It looks like Base64 but according to Should the token in the header be base64 encoded?, it is not.

Digging a bit deeper in to "HTTP/1.1, part 7: Authentication"**, however, I see that b64token is just an ABNF syntax definition allowing for characters typically used in base64, base64url, etc.. So the b64token doesn't define any encoding or decoding but rather just defines what characters can be used in the part of the Authorization header that will contain the access token.

This fully addresses the first 3 items in the OP question's list. So I'm extending this answer to address the 4th question, about whether the token must be validated, so @mon feel free to remove or edit:

The authorizer is responsible for accepting or rejecting the http request. If the authorizer says the token is valid, it's up to you to decide what this means:

  • Does the authorizer have a way of inspecting the URL, identifying the operation, and looking up some role-based access control database to see if it is allowed? If yes and the request comes through, the service can assume it is allowed, and does not need to verify.
  • Is the token an all-or-nothing, so if the token is correct, all operations are allowed? Then the service doesn't need to verify.
  • Does the token mean "this request is allowed, but here is the UUID for the role, you check whether the operation is allowed". Then it's up to the service to look up that role, and see if the operation is allowed.


TransactionRequiredException Executing an update/delete query

I have also faced same issue when I work with Hibernate and Spring Jpa Data Repository. I forgot to place @Transactional on spring data repository method.

Its working for me after annotating with @Transactional.

Spring Boot value not populating

You can use Environment Class to get data :

private Environment env;
String prop= env.getProperty('some.prop');

Multipart File upload Spring Boot

In Controller, your method should be;

@RequestMapping(value = "/upload", method = RequestMethod.POST)
    public ResponseEntity<SaveResponse> uploadAttachment(@RequestParam("file") MultipartFile file, HttpServletRequest request) {

Further, you need to update application.yml (or to support maximum file size and request size.

            max-file-size: 5MB
            max-request-size: 20MB

Perform curl request in javascript?

curl is a command in linux (and a library in php). Curl typically makes an HTTP request.

What you really want to do is make an HTTP (or XHR) request from javascript.

Using this vocab you'll find a bunch of examples, for starters: Sending authorization headers with jquery and ajax

Essentially you will want to call $.ajax with a few options for the header, etc.

        url: '',
        beforeSend: function(xhr) {
             xhr.setRequestHeader("Authorization", "Bearer 6QXNMEMFHNY4FJ5ELNFMP5KRW52WFXN5")
        }, success: function(data){
            //process the JSON data etc

Spring Boot Remove Whitelabel Error Page

Manual here says that you have to set server.error.whitelabel.enabled to false to disable the standard error page. Maybe it is what you want?

I am experiencing the same error after adding /error mapping, by the way.

Understanding PrimeFaces process/update and JSF f:ajax execute/render attributes

If you have a hard time remembering the default values (I know I have...) here's a short extract from BalusC's answer:

Component    | Submit          | Refresh
------------ | --------------- | --------------
f:ajax       | execute="@this" | render="@none"
p:ajax       | process="@this" | update="@none"
p:commandXXX | process="@form" | update="@none"

How to create an alert message in jsp page after submit process is complete

You can also create a new jsp file sayng that form is submited and in your main action file just write its file name

Eg. Your form is submited is in a file succes.jsp Then your action file will have


Creating lowpass filter in SciPy - understanding methods and units

A few comments:

  • The Nyquist frequency is half the sampling rate.
  • You are working with regularly sampled data, so you want a digital filter, not an analog filter. This means you should not use analog=True in the call to butter, and you should use scipy.signal.freqz (not freqs) to generate the frequency response.
  • One goal of those short utility functions is to allow you to leave all your frequencies expressed in Hz. You shouldn't have to convert to rad/sec. As long as you express your frequencies with consistent units, the scaling in the utility functions takes care of the normalization for you.

Here's my modified version of your script, followed by the plot that it generates.

import numpy as np
from scipy.signal import butter, lfilter, freqz
import matplotlib.pyplot as plt

def butter_lowpass(cutoff, fs, order=5):
    nyq = 0.5 * fs
    normal_cutoff = cutoff / nyq
    b, a = butter(order, normal_cutoff, btype='low', analog=False)
    return b, a

def butter_lowpass_filter(data, cutoff, fs, order=5):
    b, a = butter_lowpass(cutoff, fs, order=order)
    y = lfilter(b, a, data)
    return y

# Filter requirements.
order = 6
fs = 30.0       # sample rate, Hz
cutoff = 3.667  # desired cutoff frequency of the filter, Hz

# Get the filter coefficients so we can check its frequency response.
b, a = butter_lowpass(cutoff, fs, order)

# Plot the frequency response.
w, h = freqz(b, a, worN=8000)
plt.subplot(2, 1, 1)
plt.plot(0.5*fs*w/np.pi, np.abs(h), 'b')
plt.plot(cutoff, 0.5*np.sqrt(2), 'ko')
plt.axvline(cutoff, color='k')
plt.xlim(0, 0.5*fs)
plt.title("Lowpass Filter Frequency Response")
plt.xlabel('Frequency [Hz]')

# Demonstrate the use of the filter.
# First make some data to be filtered.
T = 5.0         # seconds
n = int(T * fs) # total number of samples
t = np.linspace(0, T, n, endpoint=False)
# "Noisy" data.  We want to recover the 1.2 Hz signal from this.
data = np.sin(1.2*2*np.pi*t) + 1.5*np.cos(9*2*np.pi*t) + 0.5*np.sin(12.0*2*np.pi*t)

# Filter the data, and plot both the original and filtered signals.
y = butter_lowpass_filter(data, cutoff, fs, order)

plt.subplot(2, 1, 2)
plt.plot(t, data, 'b-', label='data')
plt.plot(t, y, 'g-', linewidth=2, label='filtered data')
plt.xlabel('Time [sec]')


lowpass example

No serializer found for class org.hibernate.proxy.pojo.javassist.Javassist?

It could be your Hibernate entity relationship causing the issue...simply stop lazy loading of that related entity...for example...I resolved below by setting lazy="false" for customerType.

<class name="Customer" table="CUSTOMER">
        <id name="custId" type="long">
            <column name="CUSTID" />
            <generator class="assigned" />
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        <property name="phone" type="java.lang.String">
            <column name="PHONE" />
        <property name="pan" type="java.lang.String">
            <column name="PAN" />

        <many-to-one name="customerType" not-null="true" lazy="false"></many-to-one>

Error: org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'text/plain;charset=UTF-8' not supported

Building on what is mentioned in the comments, the simplest solution would be:

@RequestMapping(method = RequestMethod.PUT, consumes = MediaType.APPLICATION_JSON_VALUE)
public Collection<BudgetDTO> updateConsumerBudget(@RequestBody SomeDto someDto) throws GeneralException, ParseException {



class SomeDto {

   private List<WhateverBudgerPerDateDTO> budgetPerDate;

  //getters setters

The solution assumes that the HTTP request you are creating actually has

Content-Type:application/json instead of text/plain

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

By default, JNDI is disabled in embedded Tomcat which is causing the NoInitialContextException. You need to call Tomcat.enableNaming() to enable it. The easiest way to do that is with a TomcatEmbeddedServletContainer subclass:

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

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

If you take this approach, you can also register the DataSource in JNDI by overriding the postProcessContext method in your TomcatEmbeddedServletContainerFactory subclass.

context.getNamingResources().addResource adds the resource to the java:comp/env context so the resource's name should be jdbc/mydatasource not java:comp/env/mydatasource.

Tomcat uses the thread context class loader to determine which JNDI context a lookup should be performed against. You're binding the resource into the web app's JNDI context so you need to ensure that the lookup is performed when the web app's class loader is the thread context class loader. You should be able to achieve this by setting lookupOnStartup to false on the jndiObjectFactoryBean. You'll also need to set expectedType to javax.sql.DataSource:

<bean class="org.springframework.jndi.JndiObjectFactoryBean">
    <property name="jndiName" value="java:comp/env/jdbc/mydatasource"/>
    <property name="expectedType" value="javax.sql.DataSource"/>
    <property name="lookupOnStartup" value="false"/>

This will create a proxy for the DataSource with the actual JNDI lookup being performed on first use rather than during application context startup.

The approach described above is illustrated in this Spring Boot sample.

How to stick table header(thead) on top while scrolling down the table rows with fixed header(navbar) in bootstrap 3?

I accomplished something similar using jQuery Waypoints.

There's a lot of moving parts, and quite a bit of logic (that I hope to get on GitHub some day soon), but essentially what you could do is...

  1. Duplicate the table DOM structure in JavaScript and add a class called fixed.
  2. Add styles for table.fixed that make it invisible.
  3. Set a way point at the bottom of the header navigation that adds a class called sticky to table.fixed
  4. Add styles for table.sticky.fixed that position it just below the navbar and also make just the thead content visible. This also has a z-index so it is laid above the rest of the content.
  5. Add another waypoint, but in the downward scroll event, that removes .sticky from the table.fixed

You have to duplicate the entire table DOM in order to ensure column widths line up appropriately.

If that sounds really complicated, you might want to try playing around with the DataTables plugin and the FixedHeader extension:

Failed to load ApplicationContext from Unit Test: FileNotFound

Add in in pom.xml give the following plugin:


javac: invalid target release: 1.8

Most of the time, these type of issues happen due to incorrect java version. Make sure your PATH and JAVA_HOME variables are pointing to the correct version.

Could not extract response: no suitable HttpMessageConverter found for response type

As Artem Bilan said, this problem occures because MappingJackson2HttpMessageConverter supports response with application/json content-type only. If you can't change server code, but can change client code(I had such case), you can change content-type header with interceptor:

restTemplate.getInterceptors().add((request, body, execution) -> {
            ClientHttpResponse response = execution.execute(request,body);
            return response;

How can I trigger the click event of another element in ng-click using angularjs?

One more directive




  return {
    restrict: 'AE', 
    template: '<div></div>', 
    link: function(s,e,a){

      var el = angular.element(e);
      var button = angular.element('<button type="button" class="btn btn-default btn-upload">Add File</button>'); 
      var fileForm = angular.element('<input type="file" style="display:none;"/>'); 

      fileForm.on('change', function(){
         // Actions after the file is selected
         console.log( fileForm[0].files[0].name );



Store a closure as a variable in Swift


@interface PopupView : UIView
@property (nonatomic, copy) void (^onHideComplete)();

@interface PopupView ()


- (IBAction)hideButtonDidTouch:(id sender) {
    // Do something
    // Callback
    if (onHideComplete) onHideComplete ();


PopupView * popupView = [[PopupView alloc] init]
popupView.onHideComplete = ^() {


class PopupView: UIView {
    var onHideComplete: (() -> Void)?

    @IBAction func hideButtonDidTouch(sender: AnyObject) {
        // Do something
        // Callback
        if let callback = self.onHideComplete {
            callback ()

var popupView = PopupView ()
popupView.onHideComplete = {
    () -> Void in 

Spring data jpa- No bean named 'entityManagerFactory' is defined; Injection of autowired dependencies failed

In my specific case I seemed to have been missing the dependency

 <!-- -->

Label encoding across multiple columns in scikit-learn

No, LabelEncoder does not do this. It takes 1-d arrays of class labels and produces 1-d arrays. It's designed to handle class labels in classification problems, not arbitrary data, and any attempt to force it into other uses will require code to transform the actual problem to the problem it solves (and the solution back to the original space).

bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?

In some references, use the second instead of the first:

soup_object= BeautifulSoup(markup,'html-parser')
soup_object= BeautifulSoup(markup,'html.parser')

SSL Error: unable to get local issuer certificate

If you are a linux user Update node to a later version by running

sudo apt update

 sudo apt install build-essential checkinstall libssl-dev

curl -o- | bash

nvm --version

nvm ls

nvm ls-remote

nvm install [version.number]

this should solve your problem

Which is best data type for phone number in MySQL and what should Java type mapping for it be?

My requirement is to display 10 digit phone number in the jsp. So here's the setup for me.
MySQL: numeric(10)

Java Side:

@NumberFormat(pattern = "#")  
private long mobileNumber;

and it worked!

java.lang.ClassNotFoundException: is part of spring-core-<version>.jar

But this lib is already in your lib folder. So I guess it is just a Deployment Problem. -- Try to clean your server and redeploy your application.

self.tableView.reloadData() not working in Swift

You'll need to reload the table on the UI thread via:

//swift 2.3
dispatch_async(dispatch_get_main_queue(), { () -> Void in

//swift 5

Follow up: An easier alternative to the connection.start() approach is to instead use NSURLConnection.sendAsynchronousRequest(...)

//NSOperationQueue.mainQueue() is the main thread
NSURLConnection.sendAsynchronousRequest(NSURLRequest(URL: url), queue: NSOperationQueue.mainQueue()) { (response, data, error) -> Void in
    //check error
    var jsonError: NSError?
    let json: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.allZeros, error: &jsonError)
    //check jsonError

This doesn't allow you the flexibility of tracking the bytes though, for example you might want to calculate the progress of the download via bytesDownloaded/bytesNeeded

connecting MySQL server to NetBeans

Fist of all make sure your SQL server is running. Actually I'm working on windows and I have installed a nice tool which is called MySQL workbench (you can find it here for almost any platform ).

you can see the server is running

Thus I just create a new database to test the connection, let's call it stackoverflow, with one table called user.


DROP SCHEMA IF EXISTS `stackoverflow` ;
USE `stackoverflow` ;

-- -----------------------------------------------------
-- Table `stackoverflow`.`user`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `stackoverflow`.`user` ;

CREATE TABLE IF NOT EXISTS `stackoverflow`.`user` (
  `name` VARCHAR(75) NOT NULL,
  `email` VARCHAR(150) NOT NULL,
  PRIMARY KEY (`iduser`),
  UNIQUE INDEX `iduser_UNIQUE` (`iduser` ASC),
  UNIQUE INDEX `email_UNIQUE` (`email` ASC))


You can reduce important part to


 CREATE TABLE IF NOT EXISTS `stackoverflow`.`user` (
      `name` VARCHAR(75) NOT NULL,
      `email` VARCHAR(150) NOT NULL,
      PRIMARY KEY (`iduser`),
      UNIQUE INDEX `iduser_UNIQUE` (`iduser` ASC),
      UNIQUE INDEX `email_UNIQUE` (`email` ASC))

So now I have my brand new stackoverflow database. Let's connect to it throught Netbeans. Launch netbeans and go to the services panel list of connections available Now right click on databases: new connection.. Choose MySql connector, they already come packed with netbeans. connector Then fill in the gaps the data you need. As shown in the picture add the database name and remove from the connection url the optional parameters as l?zeroDateTimeBehaviour=convertToNull . Use the right user name and password and test the connection. data

As you can see connection is successful.


You will have your connection successfully working and available under the services.


Spring Boot - Cannot determine embedded database driver class for database type NONE

I tried all the mentioned things above but could not resolve the issue. I am using SQLite and my SQLite file was in the resources directory.

a) Set Up done for IDE

I need to manually add below lines in the .classpath file of my project.

<classpathentry kind="src" path="resources"/>
<classpathentry kind="output" path="target/classes"/>

After that, I refreshed and Cleaned the project from MenuBar at the top. like Project->Clean->My Project Name.

After that, I run the project and problem resolved. for my project is


b) Set Up done if Jar deployment throw same error

You need to add following lines to your pom.xml


May be it may help someone.

Mipmap drawables for icons

mipmap-mdpi/ic_launcher.png (48x48 pixels)
mipmap-hdpi/ic_launcher.png (72x72)
mipmap-xhdpi/ic_launcher.png (96x96)
mipmap-xxhdpi/ic_launcher.png (144x144)
mipmap-xxxhdpi/ic_launcher.png (192x192)

MipMap for app icon for launcher

Spring boot Security Disable security

Add the below lines to your main app.

Remove org.activiti.spring.boot.SecurityAutoConfiguration.class if you're not using activiti.

Similarly, remove the one for actuator if you're not using spring-boot-actuator.

@EnableAutoConfiguration(exclude = {
org.springframework.boot.actuate.autoconfigure.ManagementWebSecurityAutoConfiguration.class, })

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'MyController':

Change from @Controller to @Service to CompteController and add @Service annotation to CompteDAOHib. Let me know if you still face this issue.

Node/Express file upload

If you are using Node.js Express and Typescript here is a working example, this works with javascript also, just change the let to var and the import to includes etc...

first import the following make sure you install formidable by running the following command:

npm install formidable

than import the following:

  import * as formidable from 'formidable';
  import * as fs from 'fs';

then your function like bellow:

    uploadFile(req, res) {
    let form = new formidable.IncomingForm();
    form.parse(req, function (err, fields, files) {
        let oldpath = files.file.path;
        let newpath = 'C:/test/' +;
        fs.rename(oldpath, newpath, function (err) {
            if (err) throw err;
            res.write('File uploaded and moved!');

Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener

If you are sure you haven't messed the jar, then please clean the project and perform mvn clean install. This should solve the problem.

How to test Spring Data repositories?

In the last version of spring boot 2.1.1.RELEASE, it is simple as :

@SpringBootTest(classes = SampleApplication.class)
public class CustomerRepositoryIntegrationTest {

    CustomerRepository repository;

    public void myTest() throws Exception {

        Customer customer = new Customer();

        List<?> queryResult = repository.findByLastName("Wick");


Complete code:

Using BeautifulSoup to extract text without tags

you can try this indside findall for loop:

item_price = item.find('span', attrs={'class':'s-item__price'}).text

it extracts only text and assigs it to "item_pice"

python BeautifulSoup parsing table

Here is working example for a generic <table>. (question links-broken)

Extracting the table from here countries by GDP (Gross Domestic Product).

htmltable = soup.find('table', { 'class' : 'table table-striped' })
# where the dictionary specify unique attributes for the 'table' tag

The tableDataText function parses a html segment started with tag <table> followed by multiple <tr> (table rows) and inner <td> (table data) tags. It returns a list of rows with inner columns. Accepts only one <th> (table header/data) in the first row.

def tableDataText(table):       
    rows = []
    trs = table.find_all('tr')
    headerow = [td.get_text(strip=True) for td in trs[0].find_all('th')] # header row
    if headerow: # if there is a header row include first
        trs = trs[1:]
    for tr in trs: # for every table row
        rows.append([td.get_text(strip=True) for td in tr.find_all('td')]) # data row
    return rows

Using it we get (first two rows).

list_table = tableDataText(htmltable)

  "GDP (IMF '19)",
  "GDP (UN '16)",
  'GDP Per Capita',
  '2019 Population'],
  'United States',
  '21.41 trillion',
  '18.62 trillion',

That can be easily transformed in a pandas.DataFrame for more advanced tools.

import pandas as pd
dftable = pd.DataFrame(list_table[1:], columns=list_table[0])

pandas DataFrame html table output

How to set up datasource with Spring for HikariCP?

This last error is caused by the library SLF4J not being found. HikariCP has two dependencies: slf4j and javassist. BTW, HikariDataSource does have a default constructor and does not need HikariConfig, see this link. So that was never the problem.

org.hibernate.hql.internal.ast.QuerySyntaxException: table is not mapped

In my case I just forgot to add nativeQuery = true

@Query( value = "some sql query ...", nativeQuery = true)

For Spring Boot with Spring Data JPA

WebService Client Generation Error with JDK8

The following works for wsimport 2.2.9 included in jdk 1.8.0_66:

wsimport -J-Djavax.xml.accessExternalSchema=all ....

Spring Boot JPA - configuring auto reconnect

As some people already pointed out, spring-boot 1.4+, has specific namespaces for the four connections pools. By default, hikaricp is used in spring-boot 2+. So you will have to specify the SQL here. The default is SELECT 1. Here's what you would need for DB2 for example: spring.datasource.hikari.connection-test-query=SELECT current date FROM sysibm.sysdummy1

Caveat: If your driver supports JDBC4 we strongly recommend not setting this property. This is for "legacy" drivers that do not support the JDBC4 Connection.isValid() API. This is the query that will be executed just before a connection is given to you from the pool to validate that the connection to the database is still alive. Again, try running the pool without this property, HikariCP will log an error if your driver is not JDBC4 compliant to let you know. Default: none

Google OAUTH: The redirect URI in the request did not match a registered redirect URI

You need to go into the developer console and set


as your callback URL.

This video is slightly outdated, as it shows the older Developer Console instead of the new one, however, the concepts should still apply. You need to find your project in the developer console and register a callback URL.

Printing Mongo query output to a file while in the mongo shell

If you invoke the shell with script-file, db address, and --quiet arguments, you can redirect the output (made with print() for example) to a file:

mongo localhost/mydatabase --quiet myScriptFile.js > output 

Configuration with name 'default' not found. Android Studio

I also faced the same problem and the problem was that the libraries were missing in some of the following files.

settings.gradle, app/build.gradle, package.json,

Suppose the library is react-native-vector-icons then it should be mentioned in following files;

In app/build.gradle file under dependencies section add:

compile project(':react-native-vector-icons')

In settings.gradle file under android folder, add the following:

include ':react-native-vector-icons' project(':react-native-vector-icons').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-vector-icons/android')

In, add the following:

Import the dependency: import com.oblador.vectoricons.VectorIconsPackage;

and then add: new VectorIconsPackage() in getPackages() method.

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

For those who use Tomcat with Bitronix, this will fix the problem:

The error indicates that no handler could be found for your datasource 'jdbc/mydb', so you'll need to make sure your tomcat server refers to your bitronix configuration files as needed.

In case you're using and files to configure the datasource, specify these two JVM arguments in tomcat:

(if you already used them, make sure your references are correct):

  • btm.root


-Dbtm.root="C:\Program Files\Apache Software Foundation\Tomcat 7.0.59""C:\Program Files\Apache Software Foundation\Tomcat 7.0.59\conf\" 

Now, restart your server and check the log.

Why does my Spring Boot App always shutdown immediately after starting?

I was having a similar problem. I only had the following starter web package.


But it is not enough. You need to add a parent too to get other required dependencies.

    <relativePath/> <!-- lookup parent from repository -->

@RequestParam in Spring MVC handling optional parameters

You need to give required = false for name and password request parameters as well. That's because, when you provide just the logout parameter, it actually expects for name and password as well as they are still mandatory.

It worked when you just gave name and password because logout wasn't a mandatory parameter thanks to required = false already given for logout.

Basic HTTP and Bearer Token Authentication

Standard ( says you can use:

  • Form-Encoded Body Parameter: Authorization: Bearer mytoken123
  • URI Query Parameter: access_token=mytoken123

So it's possible to pass many Bearer Token with URI, but doing this is discouraged (see section 5 in the standard).

Starting of Tomcat failed from Netbeans

It affects at least NetBeans versions 7.4 through 8.0.2. It was first reported from version 8.0 and fixed in NetBeans 8.1. It would have had the problem for any tomcat version (confirmed for versions 7.0.56 through 8.0.28).

Specifics are described as Netbeans bug #248182.

This problem is also related to postings mentioning the following error output:

'*' is not recognized as an internal or external command, operable program or batch file.

For a tomcat installed from the zip file, I fixed it by changing the catalina.bat file in the tomcat bin directory.

Find the bellow configuration in your catalina.bat file.



And change it as in below by removing the double quotes:



Now save your changes, and start your tomcat from within NetBeans.

org.apache.poi.POIXMLException: org.apache.poi.openxml4j.exceptions.InvalidFormatException:

You are trying to access an XLS file. However, you are using XSSFWorkbook and XSSFSheet class objects. These classes are mainly used for XLSX files.

For XLS file: HSSFWorkbook & HSSFSheet
For XLSX file: XSSFSheet & XSSFSheet

So in place of XSSFWorkbook use HSSFWorkbook and in place of XSSFSheet use HSSFSheet.

So your code should look like this after the changes are made:

HSSFWorkbook workbook = new HSSFWorkbook(file);

HSSFSheet sheet = workbook.getSheetAt(0);

Why is printing "B" dramatically slower than printing "#"?

Pure speculation is that you're using a terminal that attempts to do word-wrapping rather than character-wrapping, and treats B as a word character but # as a non-word character. So when it reaches the end of a line and searches for a place to break the line, it sees a # almost immediately and happily breaks there; whereas with the B, it has to keep searching for longer, and may have more text to wrap (which may be expensive on some terminals, e.g., outputting backspaces, then outputting spaces to overwrite the letters being wrapped).

But that's pure speculation.

Display Records From MySQL Database using JTable in Java

this is the easy way to do that you just need to download the jar file "rs2xml.jar" add it to your project and do that : 1- creat a connection 2- statment and resultset 3- creat a jtable 4- give the result set to DbUtils.resultSetToTableModel(rs) as define in this methode you well get your jtable so easy.

public void afficherAll(String tableName){
        String sql="select * from "+tableName;
        try {
        } catch (SQLException e) {
            // TODO Auto-generated catch block
             JOptionPane.showMessageDialog(null, e);

How to write JUnit test with Spring Autowire?

You should make another XML-spring configuration file in your test resource folder or just copy the old one, it looks fine, but if you're trying to start a web context for testing a micro service, just put the following code as your master test class and inherits from that:

@ContextConfiguration(locations = "classpath*:spring-test-config.xml")
public abstract class AbstractRestTest {
    private WebApplicationContext wac;

Spring get current ApplicationContext

Even better than having it with @Autowired is to let it be injected via constructor. Find some arguments pro constructor injection here

public class MyClass{
  private final ApplicationContext applicationContext;

  public MyClass(ApplicationContext applicationContext){
    this.applicationContext = applicationContext;

  //here will be your methods using the applicationcontext

Spring Boot: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean

use this one in your pom.xml :


or this one :


Jboss server error : Failed to start service jboss.deployment.unit."jbpm-console.war"

I had the exact same problem, found that I was missing

  <resource-adapter-ref resource-adapter-name="hornetq-ra"/>  
  <bean-instance-pool-ref pool-name="mdb-strict-max-pool"/>  


<subsystem xmlns="urn:jboss:domain:ejb3:1.2">  

in standalone/configuration/standalone.xml

How to fix 'sudo: no tty present and no askpass program specified' error?


ssh -t remotehost "sudo <cmd>"

This will remove the above errors.

Log4j2 configuration - No log4j2 configuration file found

Eclipse will never see a file until you force a refresh of the IDE. Its a feature! So you can put the file all over the project and Eclipse will ignore it completely and throw these errors. Hit refresh in Eclipse project view and then it works.

Converting list to *args when calling function

You can use the * operator before an iterable to expand it within the function call. For example:

timeseries_list = [timeseries1 timeseries2 ...]
r = scikits.timeseries.lib.reportlib.Report(*timeseries_list)

(notice the * before timeseries_list)

From the python documentation:

If the syntax *expression appears in the function call, expression must evaluate to an iterable. Elements from this iterable are treated as if they were additional positional arguments; if there are positional arguments x1, ..., xN, and expression evaluates to a sequence y1, ..., yM, this is equivalent to a call with M+N positional arguments x1, ..., xN, y1, ..., yM.

This is also covered in the python tutorial, in a section titled Unpacking argument lists, where it also shows how to do a similar thing with dictionaries for keyword arguments with the ** operator.

how to get date of yesterday using php?

Step 1

We need set format data in function date(): Function date() returns a string formatted according to the givenformat string using the given integer timestamp or the current time ifno timestamp is given. In other words, timestampis optional anddefaults to the value of time().

echo date("F j, Y");

result: March 30, 2010

Step 2

For "yesterday" date use php function mktime(): Function mktime() returns the Unix timestamp corresponding to thearguments given. This timestamp is a long integer containing the numberof seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and thetime specified. Arguments may be left out in order from right to left; any argumentsthus omitted will be set to the current value according to the localdate and time.

echo mktime(0, 0, 0, date("m"), date("d")-1, date("Y"));

result: 1269820800

Step 3

Now merge all and look at this:

$yesterday = date("Y-m-d", mktime(0, 0, 0, date("m") , date("d")-1,date("Y")));
echo $yesterday;

result: March 29, 2010

Operating similarly, it is possible to receive time hour back.

$yesterday = date("H:i:s",mktime(date("H"), 0, 0, date("m"),date("d"), date("Y")));
echo $yesterday;

result: 20:00:00

or 7 days ago:

$week = date("Y-m-d",mktime(0, 0, 0, date("m"), date("d")-7,date("Y")));
echo $week;

result: 2010-03-23

How to add scroll bar to the Relative Layout?

hi see the following sample code of xml file.

<ScrollView xmlns:android=""
    android:layout_height="fill_parent" >

        android:layout_height="fill_parent" >

            android:orientation="vertical" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >

                android:text="@+id/TextView01" >


Difference between 2 dates in SQLite

This answer is a little long-winded, and the documentation will not tell you this (because they assume you are storing your dates as UTC dates in the database), but the answer to this question depends largely on the timezone that your dates are stored in. You also don't use Date('now'), but use the julianday() function, to calculate both dates back against a common date, then subtract the difference of those results from each other.

If your dates are stored in UTC:

SELECT julianday('now') - julianday(DateCreated) FROM Payment;

This is what the top-ranked answer has, and is also in the documentation. It is only part of the picture, and a very simplistic answer, if you ask me.

If your dates are stored in local time, using the above code will make your answer WRONG by the number of hours your GMT offset is. If you are in the Eastern U.S. like me, which is GMT -5, your result will have 5 hours added onto it. And if you try making DateCreated conform to UTC because julianday('now') goes against a GMT date:

SELECT julianday('now') - julianday(DateCreated, 'utc') FROM Payment;

This has a bug where it will add an hour for a DateCreated that is during Daylight Savings Time (March-November). Say that "now" is at noon on a non-DST day, and you created something back in June (during DST) at noon, your result will give 1 hour apart, instead of 0 hours, for the hours portion. You'd have to write a function in your application's code that is displaying the result to modify the result and subtract an hour from DST dates. I did that, until I realized there's a better solution to that problem that I was having: SQLite vs. Oracle - Calculating date differences - hours

Instead, as was pointed out to me, for dates stored in local time, make both match to local time:

SELECT julianday('now', 'localtime') - julianday(DateCreated) FROM Payment;

Or append 'Z' to local time:

julianday(datetime('now', 'localtime')||'Z') - julianday(CREATED_DATE||'Z')

Both of these seem to compensate and do not add the extra hour for DST dates and do straight subtraction - so that item created at noon on a DST day, when checking at noon on a non-DST day, will not get an extra hour when performing the calculation.

And while I recognize most will say don't store dates in local time in your database, and to store them in UTC so you don't run into this, well not every application has a world-wide audience, and not every programmer wants to go through the conversion of EVERY date in their system to UTC and back again every time they do a GET or SET in the database and deal with figuring out if something is local or in UTC.

Indent List in HTML and CSS

It sounds like some of your styles are being reset.

By default in most browsers, uls and ols have margin and padding added to them.

You can override this (and many do) by adding a line to your css like so


In this case, you would remove the element from this list or add a margin/padding back, like so



How to filter data in dataview

DataView view = new DataView();
view.Table = DataSet1.Tables["Suppliers"];
view.RowFilter = "City = 'Berlin'";
view.RowStateFilter = DataViewRowState.ModifiedCurrent;
view.Sort = "CompanyName DESC";

// Simple-bind to a TextBox control
Text1.DataBindings.Add("Text", view, "CompanyName");


Grep to find item in Perl array

You seem to be using grep() like the Unix grep utility, which is wrong.

Perl's grep() in scalar context evaluates the expression for each element of a list and returns the number of times the expression was true. So when $match contains any "true" value, grep($match, @array) in scalar context will always return the number of elements in @array.

Instead, try using the pattern matching operator:

if (grep /$match/, @array) {
    print "found it\n";

Using Google Text-To-Speech in Javascript

Run this code it will take input as audio(microphone) and convert into the text than audio play.

<!doctype HTML>
<title>MY Echo</title>
<script src=""></script>
<link rel="stylesheet" type="text/css" href="" />
<style type="text/css">
    body {
        font-family: verdana;

    #result {
        height: 100px;
        border: 1px solid #ccc;
        padding: 10px;
        box-shadow: 0 0 10px 0 #bbb;
        margin-bottom: 30px;
        font-size: 14px;
        line-height: 25px;

    button {
        font-size: 20px;
        position: relative;
        left: 50%;

Speech to text converter in JS var r = document.getElementById('result');

    function startConverting() {
        if ('webkitSpeechRecognition' in window) {
            var speechRecognizer = new webkitSpeechRecognition();
            speechRecognizer.continuous = true;
            speechRecognizer.interimResults = true;
            speechRecognizer.lang = 'en-IN';
            var finalTranscripts = '';
            speechRecognizer.onresult = function(event) {
                var interimTranscripts = '';
                for (var i = event.resultIndex; i < event.results.length; i++) {
                    var transcript = event.results[i][0].transcript;
                    transcript.replace("\n", "<br>");
                    if (event.results[i].isFinal) {
                        finalTranscripts += transcript;
                        var speechresult = finalTranscripts;
                        if (speechresult) {
                            responsiveVoice.speak(speechresult, "UK English Female", {
                                pitch: 1
                            }, {
                                rate: 1
                    } else {
                        interimTranscripts += transcript;
                r.innerHTML = finalTranscripts + '<span style="color:#999">' + interimTranscripts + '</span>';
            speechRecognizer.onerror = function(event) {};
        } else {
            r.innerHTML = 'Your browser is not supported. If google chrome, please upgrade!';


Python : List of dict, if exists increment a dict value, if not append a new dict

That is a very strange way to organize things. If you stored in a dictionary, this is easy:

# This example should work in any version of Python.
# urls_d will contain URL keys, with counts as values, like: {'' : 1 }
urls_d = {}
for url in list_of_urls:
    if not url in urls_d:
        urls_d[url] = 1
        urls_d[url] += 1

This code for updating a dictionary of counts is a common "pattern" in Python. It is so common that there is a special data structure, defaultdict, created just to make this even easier:

from collections import defaultdict  # available in Python 2.5 and newer

urls_d = defaultdict(int)
for url in list_of_urls:
    urls_d[url] += 1

If you access the defaultdict using a key, and the key is not already in the defaultdict, the key is automatically added with a default value. The defaultdict takes the callable you passed in, and calls it to get the default value. In this case, we passed in class int; when Python calls int() it returns a zero value. So, the first time you reference a URL, its count is initialized to zero, and then you add one to the count.

But a dictionary full of counts is also a common pattern, so Python provides a ready-to-use class: containers.Counter You just create a Counter instance by calling the class, passing in any iterable; it builds a dictionary where the keys are values from the iterable, and the values are counts of how many times the key appeared in the iterable. The above example then becomes:

from collections import Counter  # available in Python 2.7 and newer

urls_d = Counter(list_of_urls)

If you really need to do it the way you showed, the easiest and fastest way would be to use any one of these three examples, and then build the one you need.

from collections import defaultdict  # available in Python 2.5 and newer

urls_d = defaultdict(int)
for url in list_of_urls:
    urls_d[url] += 1

urls = [{"url": key, "nbr": value} for key, value in urls_d.items()]

If you are using Python 2.7 or newer you can do it in a one-liner:

from collections import Counter

urls = [{"url": key, "nbr": value} for key, value in Counter(list_of_urls).items()]

How can I pass arguments to anonymous functions in JavaScript?


<input type="button" value="Click me" id="myButton">
    var myButton = document.getElementById("myButton");
    var test = "zipzambam";
    myButton.onclick = function(eventObject) {
        if (!eventObject) {
            eventObject = window.event;
        if (! {
   = eventObject.srcElement;
    (function(myMessage) {

Fragment transaction animation: slide in and slide out


<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="">
        android:toYDelta="100%p" />


<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="">
        android:toYDelta="0%p" />


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


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

direction = down

                    .setCustomAnimations(R.anim.slide_out_down, R.anim.slide_in_down)
                    .replace(, new CardFrontFragment())

direction = up

                    .setCustomAnimations(R.anim.slide_in_up, R.anim.slide_out_up)
                    .replace(, new CardFrontFragment())

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

Earlier this could be achieved using DOCKER_OPTS in the /etc/default/docker config file which worked on Ubuntu 14:04 and had some issues on Ubuntu 15:04. Not sure if this has been fixed.

The below line needs to go into the file /etc/default/docker on the host which runs the docker daemon. The change points to the private registry is installed in your local network. Note: you would require to restart the docker service followed with this change.

DOCKER_OPTS="--insecure-registry <priv registry hostname/ip>:<port>"

How to calculate the time interval between two time strings

Take a look at the datetime module and the timedelta objects. You should end up constructing a datetime object for the start and stop times, and when you subtract them, you get a timedelta.

Struct Constructor in C++?

Yes, but if you have your structure in a union then you cannot. It is the same as a class.

struct Example
   unsigned int mTest;

Unions will not allow constructors in the structs. You can make a constructor on the union though. This question relates to non-trivial constructors in unions.

How to get 0-padded binary representation of an integer in java?

A naive solution that work would be

String temp = Integer.toBinaryString(5);
while (temp.length() < Integer.SIZE) temp = "0"+temp; //pad leading zeros
temp = temp.substring(Integer.SIZE - Short.SIZE); //remove excess

One other method would be

String temp = Integer.toBinaryString((m | 0x80000000));
temp = temp.substring(Integer.SIZE - Short.SIZE);

This will produce a 16 bit string of the integer 5

drop down list value in

These are ALL great answers if you want to work that hard. But my guess is that you already have the items you want for the list coming from a databound element, and only want to add to the top of that list the "Hey, dude - pick one!" option. Assuming that is the case...

Here's the EASY Answer. And it ALWAYS works...

  1. Do your Databound List just like you planned.
  2. THEN, in Visual Studio, edit the items on dropdown,
  3. Add ONE MANUAL ITEM, make that your "Select an Item" choice,
  4. Using the properties window for the item in VS2012, check it as selected. Now close that window.
  5. Now, go to the properties box in Visual Studio on the lower left hand (make sure the dropdown is selected), and look for the property "AppendDataBoundItems".
  6. It will read False, set this to True.

Now you will get a Drop Down with all of your data items in it, PRECEDED BY your "Select an Item" statement made in the manual item. Try giving it a default value if possible, this will eliminate any errors you may encounter. The default is Zero, so if zero is not a problem, then leave it alone, if zero IS a problem, replace the default zero in the item with something that will NOT crash your code.

And stop working so hard...that's what Visual Studio is for.

How to strip comma in Python string

This will strip all commas from the text and left justify it.

for row in inputfile:
    place = row['your_row_number_here'].strip(', ')

? ????? ??????

Getting the WordPress Post ID of current post

you can use $post->ID for current id.

How to extract an assembly from the GAC?

Copying from a command line is unnecessary. I typed in the name of the DLL from the Start Window search. I chose See More Results. The one in the GAC was returned in the search window. I right clicked on it and said open file location. It opened in normal Windows Explorer. I copied the file. I closed the window. Done.

How to get HQ youtube thumbnails?

You need to get id from:

And put this in:

I hope that I helped :D

C++ error 'Undefined reference to Class::Function()'

In the definition of your Card class, a declaration for a default construction appears:

class Card
    // ...

    Card(); // <== Declaration of default constructor!

    // ...

But no corresponding definition is given. In fact, this function definition (from card.cpp):

void Card() {

Does not define a constructor, but rather a global function called Card that returns void. You probably meant to write this instead:

Card::Card() {

Unless you do that, since the default constructor is declared but not defined, the linker will produce error about undefined references when a call to the default constructor is found.

The same applies to your constructor accepting two arguments. This:

void Card(Card::Rank rank, Card::Suit suit) {
    cardRank = rank;
    cardSuit = suit;

Should be rewritten into this:

Card::Card(Card::Rank rank, Card::Suit suit) {
    cardRank = rank;
    cardSuit = suit;

And the same also applies for other member functions: it seems you did not add the Card:: qualifier before the member function names in their definitions. Without it, those functions are global functions rather than definitions of member functions.

Your destructor, on the other hand, is declared but never defined. Just provide a definition for it in card.cpp:

Card::~Card() { }

Most efficient way to reverse a numpy array

In order to have it working with negative numbers and a long list you can do the following:

b = numpy.flipud(numpy.array(a.split(),float))

Where flipud is for 1d arra

How to preview a part of a large pandas DataFrame, in iPython notebook?

To see the first n rows of DataFrame:

df.head(n) # (n=5 by default)

To see the last n rows:


NewtonSoft.Json Serialize and Deserialize class with property of type IEnumerable<ISomeInterface>

You don't need to use JsonConverterAttribute, keep your model clean, also use CustomCreationConverter, the code is simpler:

public class SampleConverter : CustomCreationConverter<ISample>
    public override ISample Create(Type objectType)
        return new Sample();


var sz = JsonConvert.SerializeObject( sampleGroupInstance );
JsonConvert.DeserializeObject<SampleGroup>( sz, new SampleConverter());

Documentation: Deserialize with CustomCreationConverter

iframe refuses to display

For any of you calling back to the same server for your IFRAME, pass this simple header inside the IFRAME page:

Content-Security-Policy: frame-ancestors 'self'

Or, add this to your web server's CSP configuration.

Iterate through dictionary values?

If all your values are unique, you can make a reverse dictionary:

PIXO_reverse = {v: k for k, v in PIX0.items()}


>>> PIXO_reverse

{'320x240': 'QVGA', '640x480': 'VGA', '800x600': 'SVGA'}

Now you can use the same logic as before.

Return JSON for ResponseEntity<String>

The root of the problem is that Spring (via ResponseEntity, RestController, and/or ResponseBody) will use the contents of the string as the raw response value, rather than treating the string as JSON value to be encoded. This is true even when the controller method uses produces = MediaType.APPLICATION_JSON_VALUE, as in the question here.

It's essentially like the difference between the following:

// yields: This is a String
System.out.println("This is a String");

// yields: "This is a String"
System.out.println("\"This is a String\"");

The first output cannot be parsed as JSON, but the second output can.

Something like '"'+myString+'"' is probably not a good idea however, as that won't handle proper escaping of double-quotes within the string and will not produce valid JSON for any such string.

One way to handle this would be to embed your string inside an object or list, so that you're not passing a raw string to Spring. However, that changes the format of your output, and really there's no good reason not to be able to return a properly-encoded JSON string if that's what you want to do. If that's what you want, the best way to handle it is via a JSON formatter such as Json or Google Gson. Here's how it might look with Gson:


public class MyController

    private static final Gson gson = new Gson();

    @RequestMapping(value = "so", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    ResponseEntity<String> so() {
        return ResponseEntity.ok(gson.toJson("This is a String"));

Array and string offset access syntax with curly braces is deprecated

It's really simple to fix the issue, however keep in mind that you should fork and commit your changes for each library you are using in their repositories to help others as well.

Let's say you have something like this in your code:

$str = "test";

since PHP 7.4 curly braces method to get individual characters inside a string has been deprecated, so change the above syntax into this:

$str = "test";

Fixing the code in the question will look something like this:

public function getRecordID(string $zoneID, string $type = '', string $name = ''): string
    $records = $this->listRecords($zoneID, $type, $name);
    if (isset($records->result[0]->id)) {
        return $records->result[0]->id;
    return false;

Accessing member of base class

You are incorrectly using the super and this keyword. Here is an example of how they work:

class Animal {
    public name: string;
    constructor(name: string) { = name;
    move(meters: number) {
        console.log( + " moved " + meters + "m.");

class Horse extends Animal {
    move() {
        console.log( + " is Galloping...");
        console.log( + " is Galloping...");

var tom: Animal = new Horse("Tommy the Palomino"); = 'horseee'; 

// Outputs:

// horseee is Galloping...
// Tommy the Palomino is Galloping...
// Tommy the Palomino moved 45m.


  1. The first log outputs, this refers to the prototype chain of the object tom, not the object tom self. Because we have added a name property on the Animal.prototype, horseee will be outputted.
  2. The second log outputs, the this keyword refers to the the tom object itself.
  3. The third log is logged using the move method of the Animal base class. This method is called from Horse class move method with the syntax super.move(45);. Using the super keyword in this context will look for a move method on the prototype chain which is found on the Animal prototype.

Remember TS still uses prototypes under the hood and the class and extends keywords are just syntactic sugar over prototypical inheritance.

Is it possible to use an input value attribute as a CSS selector?

Yes, but note: since the attribute selector (of course) targets the element's attribute, not the DOM node's value property (elem.value), it will not update while the form field is being updated.

Otherwise (with some trickery) I think it could have been used to make a CSS-only substitute for the "placeholder" attribute/functionality. Maybe that's what the OP was after? :)

How to get height of Keyboard?

Update Swift 4.2

private func setUpObserver() {
    NotificationCenter.default.addObserver(self, selector: .keyboardWillShow, name: UIResponder.keyboardWillShowNotification, object: nil)

selector method:

@objc fileprivate func keyboardWillShow(notification:NSNotification) {
    if let keyboardRectValue = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        let keyboardHeight = keyboardRectValue.height


private extension Selector {
    static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(notification:)) 

Update Swift 3.0

private func setUpObserver() {
    NotificationCenter.default.addObserver(self, selector: .keyboardWillShow, name: .UIKeyboardWillShow, object: nil)

selector method:

@objc fileprivate func keyboardWillShow(notification:NSNotification) {
    if let keyboardRectValue = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        let keyboardHeight = keyboardRectValue.height


private extension Selector {
    static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(notification:)) 


UIKeyboardDidShowNotification or UIKeyboardWillShowNotification might called twice and got different result, this article explained why called twice.

In Swift 2.2

Swift 2.2 deprecates using strings for selectors and instead introduces new syntax: #selector.

Something like:

private func setUpObserver() {

    NSNotificationCenter.defaultCenter().addObserver(self, selector: .keyboardWillShow, name: UIKeyboardWillShowNotification, object: nil)

selector method:

@objc private func keyboardWillShow(notification:NSNotification) {

    let userInfo:NSDictionary = notification.userInfo!
    let keyboardFrame:NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
    let keyboardRectangle = keyboardFrame.CGRectValue()
    let keyboardHeight = keyboardRectangle.height
    editorBottomCT.constant = keyboardHeight


    private extension Selector {

    static let keyboardWillShow = #selector(YourViewController.keyboardWillShow(_:)) 

Gradient borders

It's a hack, but you can achieve this effect in some cases by using the background-image to specify the gradient and then masking the actual background with a box-shadow. For example:

p {
  display: inline-block;
  width: 50px;
  height: 50px;
  /* The background is used to specify the border background */
  background: -moz-linear-gradient(45deg, #f00, #ff0);
  background: -webkit-linear-gradient(45deg, #f00, #ff0);
  /* Background origin is the padding box by default.
  Override to make the background cover the border as well. */
  -moz-background-origin: border;
  background-origin: border-box;
  /* A transparent border determines the width */
  border: 4px solid transparent;
  border-radius: 8px;
    inset 0 0 12px #0cc, /* Inset shadow */
    0 0 12px #0cc, /* Outset shadow */
    inset -999px 0 0 #fff; /* The background color */


Tomcat Servlet: Error 404 - The requested resource is not available

You definitely need to map your servlet onto some URL. If you use Java EE 6 (that means at least Servlet API 3.0) then you can annotate your servlet like

@WebServlet(name="helloServlet", urlPatterns={"/hello"})
public class HelloWorld extends HttpServlet {
     //rest of the class

Then you can just go to the localhost:8080/yourApp/hello and the value should be displayed. In case you can't use Servlet 3.0 API than you need to register this servlet into web.xml file like


Error in : figure margins too large in R

enter image description here

Just zoom this area if you use RStudio.

@Html.DisplayFor - DateFormat ("mm/dd/yyyy")

I have been using this change in my code :

old code :

  @Html.DisplayFor(modelItem => item.dataakt)

new :


jQuery Ajax error handling, show custom exception messages

First we need to set <serviceDebug includeExceptionDetailInFaults="True" /> in web.config:

 <behavior name=""> 
  <serviceMetadata httpGetEnabled="true" /> 
    **<serviceDebug includeExceptionDetailInFaults="true" />** 

In addition to that at jquery level in error part you need to parse error response that contains exception like:

.error(function (response, q, t) { 
  var r = jQuery.parseJSON(response.responseText); 

Then using r.Message you can actully show exception text.

Check complete code:

Faster alternative in Oracle to SELECT COUNT(*) FROM sometable

If the table has an index on a NOT NULL column the COUNT(*) will use that. Otherwise it is executes a full table scan. Note that the index doesn't have to be UNIQUE it just has to be NOT NULL.

Here is a table...

SQL> desc big23
 Name                                      Null?    Type
 ----------------------------------------- -------- ---------------------------
 PK_COL                                    NOT NULL NUMBER
 COL_1                                              VARCHAR2(30)
 COL_2                                              VARCHAR2(30)
 COL_3                                              NUMBER
 COL_4                                              DATE
 COL_5                                              NUMBER
 NAME                                               VARCHAR2(10)


First we'll do a count with no indexes ....

SQL> explain plan for
  2      select count(*) from big23
  3  /


SQL> select * from table(dbms_xplan.display)
  2  /
select * from table)dbms_xplan.display)

Plan hash value: 983596667

| Id  | Operation          | Name  | Rows  | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |       |     1 |  1618   (1)| 00:00:20 |
|   1 |  SORT AGGREGATE    |       |     1 |            |          |
|   2 |   TABLE ACCESS FULL| BIG23 |   472K|  1618   (1)| 00:00:20 |


   - dynamic sampling used for this statement

13 rows selected.


No we create an index on a column which can contain NULL entries ...

SQL> create index i23 on big23(col_5)
  2  /

Index created.

SQL> delete from plan_table
  2  /

3 rows deleted.

SQL> explain plan for
  2      select count(*) from big23
  3  /


SQL> select * from table(dbms_xplan.display)
  2  /

Plan hash value: 983596667

| Id  | Operation          | Name  | Rows  | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |       |     1 |  1618   (1)| 00:00:20 |
|   1 |  SORT AGGREGATE    |       |     1 |            |          |
|   2 |   TABLE ACCESS FULL| BIG23 |   472K|  1618   (1)| 00:00:20 |


   - dynamic sampling used for this statement

13 rows selected.


Finally let's build the index on the NOT NULL column ....

SQL> drop index i23
  2  /

Index dropped.

SQL> create index i23 on big23(pk_col)
  2  /

Index created.

SQL> delete from plan_table
  2  /

3 rows deleted.

SQL> explain plan for
  2      select count(*) from big23
  3  /


SQL> select * from table(dbms_xplan.display)
  2  /

Plan hash value: 1352920814

| Id  | Operation             | Name | Rows  | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT      |      |     1 |   326   (1)| 00:00:04 |
|   1 |  SORT AGGREGATE       |      |     1 |            |          |
|   2 |   INDEX FAST FULL SCAN| I23  |   472K|   326   (1)| 00:00:04 |


   - dynamic sampling used for this statement

13 rows selected.


Groovy built-in REST/HTTP client?

HTTPBuilder is it. Very easy to use.


def http = new HTTPBuilder('')
def html = http.get(path : '/search', query : [q:'waffles'])

It is especially useful if you need error handling and generally more functionality than just fetching content with GET.

Get everything after the dash in a string in JavaScript

Use a regular expression of the form: \w-\d+ where a \w represents a word and \d represents a digit. They won't work out of the box, so play around. Try this.

How to use ? : if statements with Razor and inline code blocks

This should work:

<span class="vote-up@(puzzle.UserVote == VoteType.Up ? "-selected" : "")">Vote Up</span>

Printing with "\t" (tabs) does not result in aligned columns

Building on this question, I use the following code to indent my messages:

String prefix1 = "short text:";
String prefix2 = "looooooooooooooong text:";
String msg = "indented";
* The second string begins after 40 characters. The dash means that the
* first string is left-justified.
String format = "%-40s%s%n";
System.out.printf(format, prefix1, msg);
System.out.printf(format, prefix2, msg);

This is the output:

short text:                             indented
looooooooooooooong text:                indented

This is documented in section "Flag characters" in man 3 printf.

How to install Java SDK on CentOS?

use the below commands to install oracle java8 through terminal

Step -1) Visit Oracle JDK download page, look for RPM version

Step -2) Download oracle java 8 using the below command wget --header "Cookie: oraclelicense=accept-securebackup-cookie"

Step -3) Install the java8 using below command sudo yum localinstall jdk-8u121-linux-x64.rpm Now the JDK should be installed at /usr/java/jdk1.8.0_121 Step -4) Remove the downloaded .rpm file to utilize the space. rm jdk-8u121-linux-x64.rpm

Step -5) Verify the java by using command java -version

Step -6) If the CentOS has multiple JDK installed, you can use the alternatives command to set the default java sudo alternatives --config java

Step -7)Optional set JAVA_HOME Environment variables. copy the path of jdk install i.e /usr/java/jdk1.8.0_121 use below command to export java home export JAVA_HOME=/usr/java/jdk1.8.0_121 export PATH=$PATH:$JAVA_HOME

How do I alter the position of a column in a PostgreSQL database table?

I don't think you can at present: see this article on the Postgresql wiki.

The three workarounds from this article are:

  1. Recreate the table
  2. Add columns and move data
  3. Hide the differences with a view.

Is it possible to create a 'link to a folder' in a SharePoint document library?

i couldn't change the permissions on the sharepoint i'm using but got a round it by uploading .url files with the drag and drop multiple files uploader.

Using the normal upload didn't work because they are intepreted by the file open dialog when you try to open them singly so it just tries to open the target not the .url file.

.url files can be made by saving a favourite with internet exploiter.

Beautiful Soup and extracting a div and its contents by ID

Here is a code fragment

soup = BeautifulSoup(:"index.html")
titleList = soup.findAll('title')
divList = soup.findAll('div', attrs={ "class" : "article story"})

As you can see I find all tags and then I find all tags with class="article" inside

Is there a <meta> tag to turn off caching in all browsers?

This is a link to a great Case Study on the industry wide misunderstanding of controlling caches.

In summary, according to this article, only Cache-Control: no-store is recognized by Chrome, Firefox, and IE. IE recognizes other controls, but Chrome and Firefox do not.

A generic list of anonymous class

Here is the answer.

string result = String.Empty;

var list = new[]
    new { Number = 10, Name = "Smith" },
    new { Number = 10, Name = "John" } 

foreach (var item in list)
    result += String.Format("Name={0}, Number={1}\n", item.Name, item.Number);


Eclipse - debugger doesn't stop at breakpoint

This could be related to one of the bugs in JDK 6 Update 14, as indicated in the release notes for JDK 6 update 15.

If this indeed turns out to be the issue, you should move to a higher version of the JDK (that's no guarantee though, since fixes have been released against 6u16, 6u18 and 7b1). The best bet is to use -XX:+UseParallelGC flag. Increasing the size of the minimum and maximum heap size, to delay the first GC, bring temporary relief.

By the way, use this bug report in Eclipse to track how others have been faring.

Find a value anywhere in a database

I wrote once a tool for myself to do exactly that thing:

a7 SqlTools

It's free and open-source:

github link

How to use jQuery to call an ASP.NET web service?

I don't know about that specific SharePoint web service, but you can decorate a page method or a web service with <WebMethod()> (in VB.NET) to ensure that it serializes to JSON. You can probably just wrap the method that webservice.asmx uses internally, in your own web service.

Dave Ward has a nice walkthrough on this.

java: ArrayList - how can I check if an index exists?

a simple way to do this:

try {
  list.get( index ); 
catch ( IndexOutOfBoundsException e ) {
  if(list.isEmpty() || index >= list.size()){
    // Adding new item to list.

E: Unable to locate package mongodb-org

I had the same issue in 14.04, but I fixed it by these steps:

  1. sudo apt-key adv --keyserver hkp:// --recv 7F0CEB10
  2. echo "deb "$(lsb_release -sc)"/mongodb- org/3.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.0.list
  3. sudo apt-get update
  4. sudo apt-get install -y mongodb

It worked like charm :)

NGinx Default public www location?

You can search for it, no matter where did they move it (system admin moved or newer version of nginx)

find / -name nginx

Storing Data in MySQL as JSON

json characters are nothing special when it comes down to storage, chars such as

{,},[,],',a-z,0-9.... are really nothing special and can be stored as text.

the first problem your going to have is this

{ profile_id: 22, username: 'Robert', password: 'skhgeeht893htgn34ythg9er' }

that stored in a database is not that simple to update unless you had your own proceedure and developed a jsondecode for mysql

UPDATE users SET JSON(user_data,'username') = 'New User';

So as you cant do that you would Have to first SELECT the json, Decode it, change it, update it, so in theory you might as well spend more time constructing a suitable database structure!

I do use json to store data but only Meta Data, data that dont get updated often, not related to the user specific.. example if a user adds a post, and in that post he adds images ill parse the images and create thumbs and then use the thumb urls in a json format.

nginx 502 bad gateway

You have to match the settings for PHP-FPM and Nginx to communicate over sockets or TCP.

So go to /etc/php5/fpm/pool.d/www.conf and look for this line:

listen = /var/run/php5-fpm.sock

Then go to /etc/nginx/nginx.conf

Look for this:

upstream php {
    server unix:/var/run/php5-fpm.socket;

Match those values and you should be all set.

Authentication failed for

If you are entering your credentials into the Visual Studio popup you might see an error that says "Login was not successful". However, this might not be true. Studio will open a browser window saying that it was in fact successful. There is then a dance between the browser and Studio where you need to accept / allow the authentication at certain points.

Get Category name from Post ID

Use get_the_category() function.

$post_categories = wp_get_post_categories( 4 );
$categories = get_the_category($post_categories[0]);

Websocket connections with Postman

It's not possible in Postman yet; But there is a new alternative for Postman, named Postwoman. it's open source and supports realtime Websocket and SSE requests.


It seems they have rebranded Postwoman to Hoppscotch and have improved the Websocket support.

Hide Signs that Meteor.js was Used

A Meteor app does not, by default, add any X-Powered-By headers to HTTP responses, as you might find in various PHP apps. The headers look like:

$ curl -I  HTTP/1.1 200 OK content-type: text/html; charset=utf-8 date: Tue, 31 Dec 2013 23:12:25 GMT connection: keep-alive 

However, this doesn't mask that Meteor was used. Viewing the source of a Meteor app will look very distinctive.

<script type="text/javascript"> __meteor_runtime_config__ = {"meteorRelease":"","ROOT_URL":"","serverId":"62a4cf6a-3b28-f7b1-418f-3ddf038f84af","DDP_DEFAULT_CONNECTION_URL":"ddp+sockjs://ddp--****"}; </script> 

If you're trying to avoid people being able to tell you are using Meteor even by viewing source, I don't think that's possible.

Pointer vs. Reference


  • A pointer is a variable that holds a memory address.
  • A pointer declaration consists of a base type, an *, and the variable name.
  • A pointer can point to any number of variables in lifetime
  • A pointer that does not currently point to a valid memory location is given the value null (Which is zero)

    BaseType* ptrBaseType;
    BaseType objBaseType;
    ptrBaseType = &objBaseType;
  • The & is a unary operator that returns the memory address of its operand.

  • Dereferencing operator (*) is used to access the value stored in the variable which pointer points to.

       int nVar = 7;
       int* ptrVar = &nVar;
       int nVar2 = *ptrVar;


  • A reference (&) is like an alias to an existing variable.

  • A reference (&) is like a constant pointer that is automatically dereferenced.

  • It is usually used for function argument lists and function return values.

  • A reference must be initialized when it is created.

  • Once a reference is initialized to an object, it cannot be changed to refer to another object.

  • You cannot have NULL references.

  • A const reference can refer to a const int. It is done with a temporary variable with value of the const

    int i = 3;    //integer declaration
    int * pi = &i;    //pi points to the integer i
    int& ri = i;    //ri is refers to integer i – creation of reference and initialization

enter image description here

enter image description here

Angular2 - Focusing a textbox on component load

Directive for autoFocus first field

import {_x000D_
} from "@angular/core";_x000D_
  selector: "[appFocusFirstEmptyInput]"_x000D_
export class FocusFirstEmptyInputDirective implements AfterViewInit {_x000D_
  constructor(private el: ElementRef) {}_x000D_
  ngAfterViewInit(): void {_x000D_
    const invalidControl = this.el.nativeElement.querySelector(".ng-untouched");_x000D_
    if (invalidControl) {_x000D_

How to fix the " No subject alternative names present" error?

This code will work like charm and use the restTemple object for rest of the code.

  RestTemplate restTemplate = new RestTemplate();   
  TrustStrategy acceptingTrustStrategy = new TrustStrategy() {
            public boolean isTrusted([] x509Certificates, String s) {
                return true;


        SSLContext sslContext = null;
        try {
            sslContext = org.apache.http.ssl.SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy)
        } catch (NoSuchAlgorithmException e) {
        } catch (KeyManagementException e) {
        } catch (KeyStoreException e) {
        SSLConnectionSocketFactory csf = new SSLConnectionSocketFactory(sslContext, new NoopHostnameVerifier());
        CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(csf).build();
        HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();


How do I convert a long to a string in C++?

Check out std::stringstream.

Blurry text after using CSS transform: scale(); in Chrome


I´ve tried all suggestions here. But diden't work. My college found a great solution, that works better:

You should NOT scale past 1.0

And include translateZ(0) in the hover but NOT in the none-hover/initial position.


a {
    transition: all 500ms cubic-bezier(0.165, 0.840, 0.440, 1.000);
    transform: scale(0.8, 0.8);

a:hover {
    transform: translateZ(0)scale(1.0, 1.0);

-didSelectRowAtIndexPath: not being called

Check if your viewController has following method:

- (BOOL) tableView:(UITableView *)tableView shouldHighlightRowAtIndexPath:(NSIndexPath *)indexPath {
    return NO;

if you return "NO" didSelectRow won't be called

Detect if value is number in MySQL

I recommend: if your search is simple , you can use `

column*1 = column

` operator interesting :) is work and faster than on fields varchar/char

SELECT * FROM myTable WHERE column*1 = column;

ABC*1 => 0 (NOT EQU **ABC**)
AB15*A => 15 (NOT EQU **AB15**)
15AB => 15 (NOT EQU **15AB**)
15 => 15 (EQUALS TRUE **15**)

How to comment and uncomment blocks of code in the Office VBA Editor

Have you checked MZTools?? It does a lot of cool stuff...

If I'm not wrong, one of the functionalities it offers is to set your own shortcuts.

Class 'App\Http\Controllers\DB' not found and I also cannot use a new Model

Try Like this:


    namespace App\Http\Controllers;

    use Illuminate\Http\Request;

    use DB;

    class UserController extends Controller

    function  index(){

    $users = DB::table('users')->get();

    foreach ($users as $user)



How do I empty an input value with jQuery?

           $('#upload input, #upload select').each(
                    var input = $(this);
                        document.getElementById(input.attr('id')).value = null;
                    }else if(input.attr('type')=='checkbox'){
                        document.getElementById(input.attr('id')).checked = false;
                    }else if(input.attr('type')=='radio'){
                        document.getElementById(input.attr('id')).checked = false;
                        document.getElementById(input.attr('id')).value = '';
                        //alert('Type: ' + input.attr('type') + ' -Name: ' + input.attr('name') + ' -Value: ' + input.val());

CSS selector for "foo that contains bar"?

No, what you are looking for would be called a parent selector. CSS has none; they have been proposed multiple times but I know of no existing or forthcoming standard including them. You are correct that you would need to use something like jQuery or use additional class annotations to achieve the effect you want.

Here are some similar questions with similar results:

Warning about `$HTTP_RAW_POST_DATA` being deprecated

If you are using WAMP...

you should add or uncomment the property always_populate_raw_post_data in php.ini and set its value to -1. In my case php.ini is located in:


..but if you are still getting the warning (as I was)

You should also set always_populate_raw_post_data = -1 in phpForApache.ini:


If you can't find this file, open a browser window and go to:


and look for the value of Loaded Configuration File key. In my case the php.ini used by WAMP is located in:

C:\wamp64\bin\apache\apache2.4.23\bin\php.ini (symlink to C:\wamp64\bin\php\php5.6.25\phpForApache.ini)

Finally restart WAMP (or click restart all services)

java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0

java.lang.UnsupportedClassVersionError happens because of a higher JDK during compile time and lower JDK during runtime.

Here's the list of versions:

Java SE 9 = 53,
Java SE 8 = 52,
Java SE 7 = 51,
Java SE 6.0 = 50,
Java SE 5.0 = 49,
JDK 1.4 = 48,
JDK 1.3 = 47,
JDK 1.2 = 46,
JDK 1.1 = 45

virtualenvwrapper and Python 3

You can add this to your .bash_profile or similar:

alias mkvirtualenv3='mkvirtualenv --python=`which python3`'

Then use mkvirtualenv3 instead of mkvirtualenv when you want to create a python 3 environment.

How to send a POST request in Go?

You have mostly the right idea, it's just the sending of the form that is wrong. The form belongs in the body of the request.

req, err := http.NewRequest("POST", url, strings.NewReader(form.Encode()))

Convert month name to month number in SQL Server

I recently had a similar experience (sql server 2012). I did not have the luxury of controlling the input, I just had a requirement to report on it. Luckily the dates were entered with leading 3 character alpha month abbreviations, so this made it simple & quick:


It worked for 12 hour:
Feb-14-2015 5:00:00 PM 2015-02-14 17:00:00.000
and 24 hour times:
Sep-27-2013 22:45 2013-09-27 22:45:00.000

(thanks ryanyuyu)

docker: Error response from daemon: Get Service Unavailable. IN DOCKER , MAC

  1. ReCheck Proxy Settings with following commands

    docker info | grep Proxy

  2. Check VPN Connectivity

  3. If VPN not using CHECK NET connectivity

  4. Reinsrtall Docker and repeat above steps.

  5. Enjoy

Drawing an SVG file on a HTML5 canvas

EDIT Dec 16th, 2019

Path2D is supported by all major browsers now

EDIT November 5th, 2014

You can now use ctx.drawImage to draw HTMLImageElements that have a .svg source in some but not all browsers. Chrome, IE11, and Safari work, Firefox works with some bugs (but nightly has fixed them).

var img = new Image();
img.onload = function() {
    ctx.drawImage(img, 0, 0);
img.src = "";

Live example here. You should see a green square in the canvas. The second green square on the page is the same <svg> element inserted into the DOM for reference.

You can also use the new Path2D objects to draw SVG (string) paths. In other words, you can write:

var path = new Path2D('M 100,100 h 50 v 50 h 50');

Live example of that here.

Old posterity answer:

There's nothing native that allows you to natively use SVG paths in canvas. You must convert yourself or use a library to do it for you.

I'd suggest looking in to canvg:

PHPMailer - SMTP ERROR: Password command failed when send mail from my server

I face the same problem, and think that I do know why this happens.

The gmail account that I use is normally used from India, and the webserver that I use is located in The Netherlands.

Google notifies that there was a login attempt from am unusualy location and requires to login from that location via a web browser.

Furthermore I had to accept suspicious access to the gmail account via

But in the end my problem is not yet solved, because I have to login to gmail from a location in The Netherlands.

I hope this will help you a little! (sorry, I do not read email replies on this email address)

error: passing xxx as 'this' argument of xxx discards qualifiers

The objects in the std::set are stored as const StudentT. So when you try to call getId() with the const object the compiler detects a problem, mainly you're calling a non-const member function on const object which is not allowed because non-const member functions make NO PROMISE not to modify the object; so the compiler is going to make a safe assumption that getId() might attempt to modify the object but at the same time, it also notices that the object is const; so any attempt to modify the const object should be an error. Hence compiler generates an error message.

The solution is simple: make the functions const as:

int getId() const {
    return id;
string getName() const {
    return name;

This is necessary because now you can call getId() and getName() on const objects as:

void f(const StudentT & s)
     cout << s.getId();   //now okay, but error with your versions
     cout << s.getName(); //now okay, but error with your versions

As a sidenote, you should implement operator< as :

inline bool operator< (const StudentT & s1, const StudentT & s2)
    return  s1.getId() < s2.getId();

Note parameters are now const reference.

Event listener for when element becomes visible?

As @figha says, if this is your own web page, you should just run whatever you need to run after you make the element visible.

However, for the purposes of answering the question (and anybody making Chrome or Firefox Extensions, where this is a common use case), Mutation Summary and Mutation Observer will allow DOM changes to trigger events.

For example, triggering an event for a elements with data-widget attribute being added to the DOM. Borrowing this excellent example from David Walsh's blog:

var observer = new MutationObserver(function(mutations) {
    // For the sake of...observation...let's output the mutation to console to see how this all works
    mutations.forEach(function(mutation) {

// Notify me of everything!
var observerConfig = {
    attributes: true, 
    childList: true, 
    characterData: true 

// Node, config
// In this case we'll listen to all changes to body and child nodes
var targetNode = document.body;
observer.observe(targetNode, observerConfig);

Responses include added, removed, valueChanged and more. valueChanged includes all attributes, including display etc.

"inconsistent use of tabs and spaces in indentation"


My Solution to this problem was to open it in idle editor and then idle editor will uncover your problem



while run:

    milli = clock.tick()
    seconds = milli/1000
    timeForLevel += seconds


while run:

       milli = clock.tick()
    seconds = milli/1000
    timeForLevel += seconds

I am not saying that you should only use idle editor. I'm saying that if you get that error you should check idle editor

pandas how to check dtype for all columns in a dataframe?

To go one step further, I assume you want to do something with these dtypes. df.dtypes.to_dict() comes in handy.

my_type = 'float64' #<---

dtypes = dataframe.dtypes.to_dict()

for col_nam, typ in dtypes.items():
    if (typ != my_type): #<---
        raise ValueError(f"Yikes - `dataframe['{col_name}'].dtype == {typ}` not {my_type}")

You'll find that Pandas did a really good job comparing NumPy classes and user-provided strings. For example: even things like 'double' == dataframe['col_name'].dtype will succeed when .dtype==np.float64.

Spring: Returning empty HTTP Responses with ResponseEntity<Void> doesn't work

Your method implementation is ambiguous, try the following , edited your code a little bit and used HttpStatus.NO_CONTENT i.e 204 No Content as in place of HttpStatus.OK

The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation. The response MAY include new or updated metainformation in the form of entity-headers, which if present SHOULD be associated with the requested variant.

Any value of T will be ignored for 204, but not for 404

  public ResponseEntity<?> taxonomyPackageExists( @PathVariable final String key ) {
            LOG.debug( "taxonomyPackageExists queried with key: {0}", key ); //$NON-NLS-1$
            final TaxonomyKey taxonomyKey = TaxonomyKey.fromString( key );
            LOG.debug( "Taxonomy key created: {0}", taxonomyKey ); //$NON-NLS-1$

            if ( this.xbrlInstanceValidator.taxonomyPackageExists( taxonomyKey ) ) {
                LOG.debug( "Taxonomy package with key: {0} exists.", taxonomyKey ); //$NON-NLS-1$
                 return new ResponseEntity<T>(HttpStatus.NO_CONTENT);
            } else {
               LOG.debug( "Taxonomy package with key: {0} does NOT exist.", taxonomyKey ); //$NON-NLS-1$
                return new ResponseEntity<T>( HttpStatus.NOT_FOUND );


Making Python loggers output all messages to stdout in addition to log file

It's possible using multiple handlers.

import logging
import auxiliary_module

# create logger with 'spam_application'
log = logging.getLogger('spam_application')

# create formatter and add it to the handlers
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')

# create file handler which logs even debug messages
fh = logging.FileHandler('spam.log')

# create console handler with a higher log level
ch = logging.StreamHandler()
log.addHandler(ch)'creating an instance of auxiliary_module.Auxiliary')
a = auxiliary_module.Auxiliary()'created an instance of auxiliary_module.Auxiliary')'calling auxiliary_module.Auxiliary.do_something')
a.do_something()'finished auxiliary_module.Auxiliary.do_something')'calling auxiliary_module.some_function()')
auxiliary_module.some_function()'done with auxiliary_module.some_function()')

# remember to close the handlers
for handler in log.handlers:

Please see:

Download history stock prices automatically from yahoo finance in python

It's trivial when you know how:

import yfinance as yf
df ='CVS', '2015-01-01')

If you wish to plot it:

import finplot as fplt

enter image description here

How to set up a PostgreSQL database in Django

$ sudo apt-get install libpq-dev

Year, this solve my problem. After execute this, do: pip install psycopg2

assembly to compare two numbers

This depends entirely on the processor you're talking about but it tends to be of the form:

cmp r1, r2
ble label7

In other words, a compare instruction to set the relevant flags, followed by a conditional branch depending on those flags.

This is generally as low as you need to get for programming. You only need to know the machine language for it if you're writing assemblers and you only need to know the microcode and/or circuit designs if you're building processors.

My kubernetes pods keep crashing with "CrashLoopBackOff" but I can't find any log

In my case the problem was what Steve S. mentioned:

The pod is crashing because it starts up then immediately exits, thus Kubernetes restarts and the cycle continues.

Namely I had a Java application whose main threw an exception (and something overrode the default uncaught exception handler so that nothing was logged). The solution was to put the body of main into try { ... } catch and print out the exception. Thus I could find out what was wrong and fix it.

(Another cause could be something in the app calling System.exit; you could use a custom SecurityManager with an overridden checkExit to prevent (or log the caller of) exit; see

Python: Get relative path from comparing two absolute paths

A write-up of jme's suggestion, using pathlib, in Python 3.

from pathlib import Path
parent = Path(r'/a/b')
son = Path(r'/a/b/c/d')            
if parent in son.parents or parent==son:
    print(son.relative_to(parent)) # returns Path object equivalent to 'c/d'

How to set value to variable using 'execute' in t-sql?

A slight change in the execute query will solve the problem:

DECLARE @dbName nvarchar(128) = 'myDb'
DECLARE @siteId int 
exec ('SELECT TOP 1 **''@siteId''** = Id FROM ' + @dbName + '..myTbl')  
select @siteId

"std::endl" vs "\n"

I've always had a habit of just using std::endl because it is easy for me to see.

Fragment MyFragment not attached to Activity

I faced similar issues when the application settings activity with the loaded preferences was visible. If I would change one of the preferences and then make the display content rotate and change the preference again, it would crash with a message that the fragment (my Preferences class) was not attached to an activity.

When debugging it looked like the onCreate() Method of the PreferencesFragment was being called twice when the display content rotated. That was strange enough already. Then I added the isAdded() check outside of the block where it would indicate the crash and it solved the issue.

Here is the code of the listener that updates the preferences summary to show the new entry. It is located in the onCreate() method of my Preferences class which extends the PreferenceFragment class:

public static class Preferences extends PreferenceFragment {
    SharedPreferences.OnSharedPreferenceChangeListener listener;

    public void onCreate(Bundle savedInstanceState) {
        // ...
        listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
            public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
                // check if the fragment has been added to the activity yet (necessary to avoid crashes)
                if (isAdded()) {
                    // for the preferences of type "list" set the summary to be the entry of the selected item
                    if (key.equals(getString(R.string.pref_fileviewer_textsize))) {
                        ListPreference listPref = (ListPreference) findPreference(key);
                        listPref.setSummary("Display file content with a text size of " + listPref.getEntry());
                    } else if (key.equals(getString(R.string.pref_fileviewer_segmentsize))) {
                        ListPreference listPref = (ListPreference) findPreference(key);
                        listPref.setSummary("Show " + listPref.getEntry() + " bytes of a file at once");
        // ...

I hope this will help others!

How to prompt for user input and read command-line arguments

To read user input you can try the cmd module for easily creating a mini-command line interpreter (with help texts and autocompletion) and raw_input (input for Python 3+) for reading a line of text from the user.

text = raw_input("prompt")  # Python 2
text = input("prompt")  # Python 3

Command line inputs are in sys.argv. Try this in your script:

import sys
print (sys.argv)

There are two modules for parsing command line options: optparse (deprecated since Python 2.7, use argparse instead) and getopt. If you just want to input files to your script, behold the power of fileinput.

The Python library reference is your friend.

Python data structure sort list alphabetically

>>> a = ()
>>> type(a)
<type 'tuple'>
>>> a = []
>>> type(a)
<type 'list'>
>>> a = {}
>>> type(a)
<type 'dict'>
>>> a =  ['Stem', 'constitute', 'Sedge', 'Eflux', 'Whim', 'Intrigue'] 
>>> a.sort()
>>> a
['Eflux', 'Intrigue', 'Sedge', 'Stem', 'Whim', 'constitute']

Checkout old commit and make it a new commit

The other answers so far create new commits that undo what is in older commits. It is possible to go back and "change history" as it were, but this can be a bit dangerous. You should only do this if the commit you're changing has not been pushed to other repositories.

The command you're looking for is git rebase --interactive

If you want to change HEAD~3, the command you want to issue is git rebase --interactive HEAD~4. This will open a text editor and allow you to specify which commits you want to change.

Practice on a different repository before you try this with something important. The man pages should give you all the rest of the information you need.

new Image(), how to know if image 100% loaded or not?

Using the Promise pattern:

function getImage(url){
        return new Promise(function(resolve, reject){
            var img = new Image()
            img.onload = function(){
            img.onerror = function(){
            img.src = url

And when calling the function we can handle its response or error quite neatly.

    //do stufff
    //do stuff

Responsive css background images

Try using background-size but using TWO ARGUMENTS One for the width and the other one for the height

background-size: 100% 100%; // Here the first argument will be the width 
// and the second will be the height.

Design DFA accepting binary strings divisible by a number 'n'

I know I am quite late, but I just wanted to add a few things to the already correct answer provided by @Grijesh. I'd like to just point out that the answer provided by @Grijesh does not produce the minimal DFA. While the answer surely is the right way to get a DFA, if you need the minimal DFA you will have to look into your divisor.

Like for example in binary numbers, if the divisor is a power of 2 (i.e. 2^n) then the minimum number of states required will be n+1. How would you design such an automaton? Just see the properties of binary numbers. For a number, say 8 (which is 2^3), all its multiples will have the last 3 bits as 0. For example, 40 in binary is 101000. Therefore for a language to accept any number divisible by 8 we just need an automaton which sees if the last 3 bits are 0, which we can do in just 4 states instead of 8 states. That's half the complexity of the machine.

In fact, this can be extended to any base. For a ternary base number system, if for example we need to design an automaton for divisibility with 9, we just need to see if the last 2 numbers of the input are 0. Which can again be done in just 3 states.

Although if the divisor isn't so special, then we need to go through with @Grijesh's answer only. Like for example, in a binary system if we take the divisors of 3 or 7 or maybe 21, we will need to have that many number of states only. So for any odd number n in a binary system, we need n states to define the language which accepts all multiples of n. On the other hand, if the number is even but not a power of 2 (only in case of binary numbers) then we need to divide the number by 2 till we get an odd number and then we can find the minimum number of states by adding the odd number produced and the number of times we divided by 2.

For example, if we need to find the minimum number of states of a DFA which accepts all binary numbers divisible by 20, we do :

20/2 = 10 
10/2 = 5

Hence our answer is 5 + 1 + 1 = 7. (The 1 + 1 because we divided the number 20 twice).

How to call gesture tap on UIView programmatically in swift

Inside ViewDidLoad

let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(imageTapped(tapGestureRecognizer:)))
    self.imgMainAdView.isUserInteractionEnabled = true

//MARK: - Image Tap Method -
@objc func imageTapped(tapGestureRecognizer: UITapGestureRecognizer)
    if let url = URL(string: self.strMAinAdvLink)
    {, options: [:])

Calling Purpose

@IBAction func btnCall1Action(_ sender: Any)
    let text = self.strPhoneNumber1!
    let test = String(text.filter { !" -()".contains($0) })
    UIApplication.shared.openURL(NSURL(string: "tel://\(test)")! as URL)

Mail Purpose


 @IBAction func btnMailAction(_ sender: Any)
    let strEmail = SAFESTRING(str:  (self.dictEventDetails?.value(forKeyPath: "") as! String))

    if !MFMailComposeViewController.canSendMail()
        AppDelegate.sharedInstance().showAlertAction(strTitle: "OK", strMessage: "Mail services are not available") { (success) in
    let composeVC = MFMailComposeViewController()
    composeVC.mailComposeDelegate = self
    composeVC.setMessageBody("", isHTML: false)
    self.present(composeVC, animated: true, completion: nil)
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?)
    controller.dismiss(animated: true, completion: nil)

Can a CSS class inherit one or more other classes?

I think this one is a better solution:

[class*=“button-“] {
  /* base button properties */
.button-primary { ... }
.button-plain { ... }

How to erase the file contents of text file in Python?

Opening a file in "write" mode clears it, you don't specifically have to write to it:

open("filename", "w").close()

(you should close it as the timing of when the file gets closed automatically may be implementation specific)

How to check if a given directory exists in Ruby


Dir[] returns an array, so it will never be nil. If you want to do it your way, you could do


which will return true if it wasn't found.

How to select all checkboxes with jQuery?

One checkbox to rule them all

For people still looking for plugin to control checkboxes through one that's lightweight, has out-of-the-box support for UniformJS and iCheck and gets unchecked when at least one of controlled checkboxes is unchecked (and gets checked when all controlled checkboxes are checked of course) I've created a jQuery checkAll plugin.

Feel free to check the examples on documentation page.

For this question example all you need to do is:

$( '#select_all' ).checkall({
    target: 'input[type="checkbox"][name="select"]'

Isn't that clear and simple?

display: inline-block extra margin

A year later, stumbled across this question for a inline LI problem, but have found a great solution that may apply here.

vertical-align:bottom on all my LI elements fixed my "extra margin" problem in all browsers.

remove None value from a list without removing the 0 value

@jamylak answer is quite nice, however if you don't want to import a couple of modules just to do this simple task, write your own lambda in-place:

>>> L = [0, 23, 234, 89, None, 0, 35, 9]
>>> filter(lambda v: v is not None, L)
[0, 23, 234, 89, 0, 35, 9]

Convert or extract TTC font to TTF - how to?

If you've got a Mac the easiest way to split those would be to use DfontSplitter, available at

The Windows version they provide doesn't work with ttc files.

cordova Android requirements failed: "Could not find an installed version of Gradle"

Solution for linux with apt-get (eg.: Ubuntu, Debian)

I have quite similar problem. I obtained error:

Error: Could not find an installed version of Gradle either in Android Studio,
or on your system to install the gradle wrapper. Please include gradle 
in your path, or install Android Studi

but without Exception. I solved it on Ubuntu by

sudo apt-get install gradle

I found also commands that allows install newest version of gradle in Ubuntu. It works only when first command is executed before (probably some dependecies are incorrect).

sudo add-apt-repository ppa:cwchien/gradle
sudo apt-get update
sudo apt-get install gradle-ppa

If it does not work, try:

export PATH=$PATH:/opt/gradle/gradle-3.5/bin

More info:

For CentOS

Instruction of instalation gradle for CentOS is under this link


Now I installing gradle by sdkman it is something like nvm for node.

Install sdkman

curl -s "" | bash 

Install gradle

sdk install gradle 4.0.2

Simple PowerShell LastWriteTime compare

I have an example I would like to share

$File = "C:\Foo.txt"
#retrieves the Systems current Date and Time in a DateTime Format
$today = Get-Date
#subtracts 12 hours from the date to ensure the file has been written to recently
$today = $today.AddHours(-12)
#gets the last time the $file was written in a DateTime Format
$lastWriteTime = (Get-Item $File).LastWriteTime

#If $File doesn't exist we will loop indefinetely until it does exist.
# also loops until the $File that exists was written to in the last twelve hours
while((!(Test-Path $File)) -or ($lastWriteTime -lt $today))
    #if a file exists then the write time is wrong so update it
    if (Test-Path $File)
        $lastWriteTime = (Get-Item $File).LastWriteTime
    #Sleep for 5 minutes
    $time = Get-Date
    Write-Host "Sleep" $time
    Start-Sleep -s 300;

Java generics: multiple generic parameters?

In your function definition you're constraining sets a and b to the same type. You can also write

public <X,Y> void myFunction(Set<X> s1, Set<Y> s2){...}

Pandas percentage of total with groupby

Simple way I have used is a merge after the 2 groupby's then doing simple division.

import numpy as np
import pandas as pd
df = pd.DataFrame({'state': ['CA', 'WA', 'CO', 'AZ'] * 3,
               'office_id': list(range(1, 7)) * 2,
               'sales': [np.random.randint(100000, 999999) for _ in range(12)]})

state_office = df.groupby(['state', 'office_id'])['sales'].sum().reset_index()
state = df.groupby(['state'])['sales'].sum().reset_index()
state_office = state_office.merge(state, left_on='state', right_on ='state', how = 'left')
state_office['sales_ratio'] = 100*(state_office['sales_x']/state_office['sales_y'])

   state  office_id  sales_x  sales_y  sales_ratio
0     AZ          2   222579  1310725    16.981365
1     AZ          4   252315  1310725    19.250033
2     AZ          6   835831  1310725    63.768601
3     CA          1   405711  2098663    19.331879
4     CA          3   710581  2098663    33.858747
5     CA          5   982371  2098663    46.809373
6     CO          1   404137  1096653    36.851857
7     CO          3   217952  1096653    19.874290
8     CO          5   474564  1096653    43.273852
9     WA          2   535829  1543854    34.707233
10    WA          4   548242  1543854    35.511259
11    WA          6   459783  1543854    29.781508

What is the meaning of the term "thread-safe"?

Yes and no.

Thread safety is a little bit more than just making sure your shared data is accessed by only one thread at a time. You have to ensure sequential access to shared data, while at the same time avoiding race conditions, deadlocks, livelocks, and resource starvation.

Unpredictable results when multiple threads are running is not a required condition of thread-safe code, but it is often a by-product. For example, you could have a producer-consumer scheme set up with a shared queue, one producer thread, and few consumer threads, and the data flow might be perfectly predictable. If you start to introduce more consumers you'll see more random looking results.

What is the best regular expression to check if a string is a valid URL?

        function validateURL(textval) {
            var urlregex = new RegExp(
            return urlregex.test(textval);

Matches | ftp://user:[email protected]:21/file/dir

Non-Matches |

How do you get an iPhone's device name

In addition to the above answer, this is the actual code:

[[UIDevice currentDevice] name];

Angular redirect to login page

Following the awesome answers above I would also like to CanActivateChild: guarding child routes. It can be used to add guard to children routes helpful for cases like ACLs

It goes like this

src/app/auth-guard.service.ts (excerpt)

import { Injectable }       from '@angular/core';
import {
  CanActivate, Router,
}                           from '@angular/router';
import { AuthService }      from './auth.service';

export class AuthGuard implements CanActivate, CanActivateChild {
  constructor(private authService: AuthService, private router:     Router) {}

  canActivate(route: ActivatedRouteSnapshot, state:    RouterStateSnapshot): boolean {
    let url: string = state.url;
    return this.checkLogin(url);

  canActivateChild(route: ActivatedRouteSnapshot, state:  RouterStateSnapshot): boolean {
    return this.canActivate(route, state);

/* . . . */

src/app/admin/admin-routing.module.ts (excerpt)

const adminRoutes: Routes = [
    path: 'admin',
    component: AdminComponent,
    canActivate: [AuthGuard],
    children: [
        path: '',
        canActivateChild: [AuthGuard],
        children: [
          { path: 'crises', component: ManageCrisesComponent },
          { path: 'heroes', component: ManageHeroesComponent },
          { path: '', component: AdminDashboardComponent }

  imports: [
  exports: [
export class AdminRoutingModule {}

This is taken from!#can-activate-guard

Visual Studio: LINK : fatal error LNK1181: cannot open input file

I solved it with the following:

Go to View-> Property Pages -> Configuration Properties -> Linker -> Input

Under additional dependencies add the thelibrary.lib. Don't use any quotations.

Difference between adjustResize and adjustPan in android?

You can use android:windowSoftInputMode="stateAlwaysHidden|adjustResize" in AndroidManifest.xml for your current activity, and use android:fitsSystemWindows="true" in styles or rootLayout.

When to use RabbitMQ over Kafka?

The only benefit that I can think of is Transactional feature, rest all can be done by using Kafka

Java8: HashMap<X, Y> to HashMap<X, Z> using Stream / Map-Reduce / Collector

A generic solution like so

public static <X, Y, Z> Map<X, Z> transform(Map<X, Y> input,
        Function<Y, Z> function) {
    return input
                    Collectors.toMap((entry) -> entry.getKey(),
                            (entry) -> function.apply(entry.getValue())));


Map<String, String> input = new HashMap<String, String>();
input.put("string1", "42");
input.put("string2", "41");
Map<String, Integer> output = transform(input,
            (val) -> Integer.parseInt(val));

Force the origin to start at 0

In the latest version of ggplot2, this can be more easy.

p <- ggplot(mtcars, aes(wt, mpg))
p + geom_point()
p+ geom_point() + scale_x_continuous(expand = expansion(mult = c(0, 0))) + scale_y_continuous(expand = expansion(mult = c(0, 0)))

enter image description here

See ?expansion() for more details.

How can you check for a #hash in a URL using JavaScript?

function getHash() {
  if (window.location.hash) {
    var hash = window.location.hash.substring(1);

    if (hash.length === 0) { 
      return false;
    } else { 
      return hash; 
  } else { 
    return false; 

How can I get a specific field of a csv file?

import csv
mycsv = csv.reader(open(myfilepath))
for row in mycsv:
   text = row[1]

Following the comments to the SO question here, a best, more robust code would be:

import csv
with open(myfilepath, 'rb') as f:
    mycsv = csv.reader(f)
    for row in mycsv:
        text = row[1]

Update: If what the OP actually wants is the last string in the last row of the csv file, there are several aproaches that not necesarily needs csv. For example,

fulltxt = open(mifilepath, 'rb').read()
laststring = fulltxt.split(',')[-1]

This is not good for very big files because you load the complete text in memory but could be ok for small files. Note that laststring could include a newline character so strip it before use.

And finally if what the OP wants is the second string in line n (for n=2):

Update 2: This is now the same code than the one in the answer from J.F.Sebastian. (The credit is for him):

import csv
line_number = 2     
with open(myfilepath, 'rb') as f:
    mycsv = csv.reader(f)
    mycsv = list(mycsv)
    text = mycsv[line_number][1]

How can I set the background color of <option> in a <select> element?

I assume you mean the <select> input element?

Support for that is pretty new, but FF 3.6, Chrome and IE 8 render this all right:

<select name="select">
  <option value="1" style="background-color: blue">Test</option>
  <option value="2" style="background-color: green">Test</option>

Javascript to set hidden form value on drop down change

  <input type="hidden" name="selval">
  <select onchange="this.form.selval.value=this.selectedIndex">

pure javascript from within a form

Static vs class functions/variables in Swift classes?

class vs static

class is used inside Reference Type(class):

  • computed property
  • method
  • can be overridden by subclass

static is used inside Reference Type and Value Type(class, enum):

  • computed property and stored property
  • method
  • cannot be changed by subclass
protocol MyProtocol {
//    class var protocolClassVariable : Int { get }//ERROR: Class properties are only allowed within classes
    static var protocolStaticVariable : Int { get }
//    class func protocolClassFunc()//ERROR: Class methods are only allowed within classes
    static func protocolStaticFunc()

struct ValueTypeStruct: MyProtocol {
    //MyProtocol implementation begin
    static var protocolStaticVariable: Int = 1
    static func protocolStaticFunc() {
    //MyProtocol implementation end
//    class var classVariable = "classVariable"//ERROR: Class properties are only allowed within classes
    static var staticVariable = "staticVariable"

//    class func classFunc() {} //ERROR: Class methods are only allowed within classes
    static func staticFunc() {}

class ReferenceTypeClass: MyProtocol {
    //MyProtocol implementation begin
    static var protocolStaticVariable: Int = 2
    static func protocolStaticFunc() {
    //MyProtocol implementation end
    var variable = "variable"

//    class var classStoredPropertyVariable = "classVariable"//ERROR: Class stored properties not supported in classes

    class var classComputedPropertyVariable: Int {
        get {
            return 1

    static var staticStoredPropertyVariable = "staticVariable"

    static var staticComputedPropertyVariable: Int {
        get {
            return 1

    class func classFunc() {}
    static func staticFunc() {}

final class FinalSubReferenceTypeClass: ReferenceTypeClass {
    override class var classComputedPropertyVariable: Int {
        get {
            return 2
    override class func classFunc() {}

//class SubFinalSubReferenceTypeClass: FinalSubReferenceTypeClass {}// ERROR: Inheritance from a final class

[Reference vs Value Type]

Convert Java string to Time, NOT Date

java.sql.Time timeValue = new java.sql.Time(formatter.parse(fajr_prayertime).getTime());

Force browser to clear cache

I had similiar problem and this is how I solved it:

  1. In index.html file I've added manifest:

    <html manifest="cache.manifest">
  2. In <head> section included script updating the cache:

    <script type="text/javascript" src="update_cache.js"></script>
  3. In <body> section I've inserted onload function:

    <body onload="checkForUpdate()">
  4. In cache.manifest I've put all files I want to cache. It is important now that it works in my case (Apache) just by updating each time the "version" comment. It is also an option to name files with "?ver=001" or something at the end of name but it's not needed. Changing just # version 1.01 triggers cache update event.

    # version 1.01
    #all other files

    It's important to include 1., 2. and 3. points only in index.html. Otherwise


    occurs because every "child" file tries to cache the page while the page is already cached.

  5. In update_cache.js file I've put this code:

    function checkForUpdate()
        if (window.applicationCache != undefined && window.applicationCache != null)
            window.applicationCache.addEventListener('updateready', updateApplication);
    function updateApplication(event)
        if (window.applicationCache.status != 4) return;
        window.applicationCache.removeEventListener('updateready', updateApplication);

Now you just change files and in manifest you have to update version comment. Now visiting index.html page will update the cache.

The parts of solution aren't mine but I've found them through internet and put together so that it works.

Automate scp file transfer using a shell script

rsync is a program that behaves in much the same way that rcp does, but has many more options and uses the rsync remote-update protocol to greatly speed up file transfers when the destination file is being updated.

The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network connection, using an efficient checksum-search algorithm described in the technical report that accompanies this package.

Copying folder from one location to another

   #!/usr/bin/expect -f   
   spawn rsync -a -e ssh [email protected]:/cool/cool1/* /tmp/cool/   
   expect "password:"   
   send "cool\r"   
   expect "*\r"   
   expect "\r"  

How to set default value for form field in Symfony2?

I usually just set the default value for specific field in my entity:

 * @var int
 * @ORM\Column(type="integer", nullable=true)
protected $development_time = 0;

This will work for new records or if just updating existing ones.

JavaScript split String with white space

You can just split on the word boundary using \b. See MDN

"\b: Matches a zero-width word boundary, such as between a letter and a space."

You should also make sure it is followed by whitespace \s. so that strings like "My car isn't red" still work:

var stringArray = str.split(/\b(\s)/);

The initial \b is required to take multiple spaces into account, e.g. my car is red

EDIT: Added grouping

Eclipse says: “Workspace in use or cannot be created, chose a different one.” How do I unlock a workspace?

I faced the same problem, but for some reasons the .lock file in workspace was not getting deleted. Even creating a new workspace was also getting locked.

So what I did was cleaning the windows temp folder, the %PREFETCH% folder and %TEMP% locations. Restart the system and then it allowed to delete the .lock file.

Maybe it will help someone.

How to correctly use the extern keyword in C

extern tells the compiler that this data is defined somewhere and will be connected with the linker.

With the help of the responses here and talking to a few friends here is the practical example of a use of extern.

Example 1 - to show a pitfall:

File stdio.h:

int errno;
/* other stuff...*/

#include <stdio.h>


#include <stdio.h>


If myCFile1.o and myCFile2.o are linked, each of the c files have separate copies of errno. This is a problem as the same errno is supposed to be available in all linked files.

Example 2 - The fix.

File stdio.h:

extern int errno;
/* other stuff...*/

File stdio.c

int errno;

#include <stdio.h>


#include <stdio.h>


Now if both myCFile1.o and MyCFile2.o are linked by the linker they will both point to the same errno. Thus, solving the implementation with extern.

Remove the last character in a string in T-SQL?

If you want to do this in two steps, rather than the three of REVERSE-STUFF-REVERSE, you can have your list separator be one or two spaces. Then use RTRIM to trim the trailing spaces, and REPLACE to replace the double spaces with ','

select REPLACE(RTRIM('a  b  c  d  '),'  ', ', ')

However, this is not a good idea if your original string can contain internal spaces.

Not sure about performance. Each REVERSE creates a new copy of the string, but STUFF is a third faster than REPLACE.

also see this

Ways to insert javascript into URL?

I don't believe you can hack via the URL. Someone could try to inject code into your application if you are passing parameters (either GET or POST) into your app so your avoidance is going to be very similar to what you'd do for a local application.

Make sure you aren't adding parameters to SQL or other script executions that were passed into the code from the browser without making sure the strings don't contain any script language. Search the next for details about injection attacks for the development platform you are working with, that should yield lots of good advice and examples.

Close dialog on click (anywhere)

If you have several dialogs that could be opened on a page, this will allow any of them to be closed by clicking on the background:

$('body').on('click','.ui-widget-overlay', function() {
    $('.ui-dialog').filter(function () {
    return $(this).css("display") === "block";

(Only works for modal dialogs, as it relies on '.ui-widget-overlay'. And it does close all open dialogs any time the background of one of them is clicked.)

QR Code encoding and decoding using zxing

this is my working example Java code to encode QR code using ZXing with UTF-8 encoding, please note: you will need to change the path and utf8 data to your path and language characters

package com.mypackage.qr;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.util.Hashtable;


public class CreateQR {

public static void main(String[] args)
    Charset charset = Charset.forName("UTF-8");
    CharsetEncoder encoder = charset.newEncoder();
    byte[] b = null;
    try {
        // Convert a string to UTF-8 bytes in a ByteBuffer
        ByteBuffer bbuf = encoder.encode(CharBuffer.wrap("utf 8 characters - i used hebrew, but you should write some of your own language characters"));
        b = bbuf.array();
    } catch (CharacterCodingException e) {

    String data;
    try {
        data = new String(b, "UTF-8");
        // get a byte matrix for the data
        BitMatrix matrix = null;
        int h = 100;
        int w = 100; writer = new MultiFormatWriter();
        try {
            Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>(2);
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            matrix = writer.encode(data,
  , w, h, hints);
        } catch ( e) {

        // change this path to match yours (this is my mac home folder, you can use: c:\\qr_png.png if you are on windows)
                String filePath = "/Users/shaybc/Desktop/OutlookQR/qr_png.png";
        File file = new File(filePath);
        try {
            MatrixToImageWriter.writeToFile(matrix, "PNG", file);
            System.out.println("printing to " + file.getAbsolutePath());
        } catch (IOException e) {
    } catch (UnsupportedEncodingException e) {


Still Reachable Leak detected by Valgrind

For future readers, "Still Reachable" might mean you forgot to close something like a file. While it doesn't seem that way in the original question, you should always make sure you've done that.

How to access SOAP services from iPhone

One word: Don't.

OK obviously that isn't a real answer. But still SOAP should be avoided at all costs. ;-) Is it possible to add a proxy server between the iPhone and the web service? Perhaps something that converts REST into SOAP for you?

You could try CSOAP, a SOAP library that depends on libxml2 (which is included in the iPhone SDK).

I've written my own SOAP framework for OSX. However it is not actively maintained and will require some time to port to the iPhone (you'll need to replace NSXML with TouchXML for a start)

How to replace NaNs by preceding values in pandas DataFrame?

You can use fillna to remove or replace NaN values.

NaN Remove

import pandas as pd

df = pd.DataFrame([[1, 2, 3], [4, None, None], [None, None, 9]])

     0    1    2
0  1.0  2.0  3.0
1  4.0  2.0  3.0
2  4.0  2.0  9.0

NaN Replace

df.fillna(0) # 0 means What Value you want to replace 
     0    1    2
0  1.0  2.0  3.0
1  4.0  0.0  0.0
2  0.0  0.0  9.0

Reference pandas.DataFrame.fillna

How to create JSON object Node.js

What I believe you're looking for is a way to work with arrays as object values:

var o = {} // empty Object
var key = 'Orientation Sensor';
o[key] = []; // empty Array, which you can push() values into

var data = {
    sampleTime: '1450632410296',
    data: '76.36731:3.4651554:0.5665419'
var data2 = {
    sampleTime: '1450632410296',
    data: '78.15431:0.5247617:-0.20050584'

This is standard JavaScript and not something NodeJS specific. In order to serialize it to a JSON string you can use the native JSON.stringify:

//> '{"Orientation Sensor":[{"sampleTime":"1450632410296","data":"76.36731:3.4651554:0.5665419"},{"sampleTime":"1450632410296","data":"78.15431:0.5247617:-0.20050584"}]}'

restrict edittext to single line

for me i do it like this , go to your textView in xml file and add this two lines

` android:maxLines="1"


How to find substring from string?

As user1511510 has identified, there's an unusual case when abc is at the end of the file name. We need to look for either /abc/ or /abc followed by a string-terminator '\0'. A naive way to do this would be to check if either /abc/ or /abc\0 are substrings:

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

int main() {
    const char *str = "/user/desktop/abc";
    const int exists = strstr(str, "/abc/") || strstr(str, "/abc\0");
    return 0;

but exists will be 1 even if abc is not followed by a null-terminator. This is because the string literal "/abc\0" is equivalent to "/abc". A better approach is to test if /abc is a substring, and then see if the character after this substring (indexed using the pointer returned by strstr()) is either a / or a '\0':

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

int main() {
    const char *str = "/user/desktop/abc", *substr;
    const int exists = (substr = strstr(str, "/abc")) && (substr[4] == '\0' || substr[4] == '/');
    return 0;

This should work in all cases.

What is the difference between Swing and AWT?

The base difference that which already everyone mentioned is that one is heavy weight and other is light weight. Let me explain, basically what the term heavy weight means is that when you're using the awt components the native code used for getting the view component is generated by the Operating System, thats why it the look and feel changes from OS to OS. Where as in swing components its the responsibility of JVM to generate the view for the components. Another statement which i saw is that swing is MVC based and awt is not.

How to use SharedPreferences in Android to store, fetch and edit values

I wanted to add here that most of the snippets for this question will have something like MODE_PRIVATE when using SharedPreferences. Well, MODE_PRIVATE means that whatever you write into this shared preference can only be read by your application only.

Whatever key you pass to getSharedPreferences() method, android creates a file with that name and stores the preference data into it. Also remember that getSharedPreferences() is supposed to be used when you intend to have multiple preference files for your application. If you intend to use single preference file and store all key-value pairs into it then use the getSharedPreference() method. Its weird why everyone (including myself) simply uses getSharedPreferences() flavor without even understanding the difference between the above two.

The following video tutorial should help

Best way to do a PHP switch with multiple values per case?

Put those many values into an array and query the array, as the switch-case seems to hide the underlying semantics of what you're trying to achieve when a string variable is used as the condition, making it harder to read and understand, e.g.:

$current_home = null;
$current_users = null;
$current_forum = null;

$lotsOfStrings = array('', 'users.location', 'users.featured', '');

if(empty($p)) {
    $current_home = 'current';

if(in_array($p,$lotsOfStrings)) {
    $current_users = 'current';

if(0 === strcmp('forum',$p)) {
    $current_forum = 'current';

How to delete SQLite database from Android programmatically

context.deleteDatabase(DATABASE_NAME); will delete the database only if all the connections are closed. If you are maintaining singleton instance for handling your database helper - it is easy to close the opened Connection.

Incase the databasehelper is used in multiple place by instantiating directly, the deleteDatabase + killProcess will do the job even if some connections are open. This can be used if the application scenario doesn't have any issues in restarting the app.

Remove plot axis values

Using base graphics, the standard way to do this is to use axes=FALSE, then create your own axes using Axis (or axis). For example,

x <- 1:20
y <- runif(20)
plot(x, y, axes=FALSE, frame.plot=TRUE)
Axis(side=1, labels=FALSE)
Axis(side=2, labels=FALSE)

The lattice equivalent is

xyplot(y ~ x, scales=list(alternating=0))

Is there a way to make HTML5 video fullscreen?

Safari supports it through webkitEnterFullscreen.

Chrome should support it since it's WebKit also, but errors out.

Chris Blizzard of Firefox said they're coming out with their own version of fullscreen which will allow any element to go to fullscreen. e.g. Canvas

Philip Jagenstedt of Opera says they'll support it in a later release.

Yes, the HTML5 video spec says not to support fullscreen, but since users want it, and every browser is going to support it, the spec will change.

Docker-Compose can't connect to Docker Daemon

just try with sudo. It seems like permission issue!

sudo docker-compose -f docker-compose-deps.yml up -d

it worked for me.

Create a txt file using batch file in a specific folder

You can also use

cd %localhost%

to set the directory to the folder the batch file was opened from. Your script would look like this:

@echo off
cd %localhost%
echo .> dblank.txt

Make sure you set the directory before you use the command to create the text file.

AngularJS ui router passing data between states without URL

The params object is included in $stateParams, but won't be part of the url.

1) In the route configuration:

$stateProvider.state('edit_user', {
    url: '/users/:user_id/edit',
    templateUrl: 'views/editUser.html',
    controller: 'editUserCtrl',
    params: {
        paramOne: { objectProperty: "defaultValueOne" },  //default value
        paramTwo: "defaultValueTwo"

2) In the controller:

.controller('editUserCtrl', function ($stateParams, $scope) {       
    $scope.paramOne = $stateParams.paramOne;
    $scope.paramTwo = $stateParams.paramTwo;

3A) Changing the State from a controller

$state.go("edit_user", {
    user_id: 1,                
    paramOne: { objectProperty: "test_not_default1" },
    paramTwo: "from controller"

3B) Changing the State in html

<div ui-sref="edit_user({ user_id: 3, paramOne: { objectProperty: 'from_html1' }, paramTwo: 'fromhtml2' })"></div>

Example Plunker

Custom "confirm" dialog in JavaScript?

To enable you to use the confirm box like the normal confirm dialog, I would use Promises which will enable you to await on the result of the outcome and then act on this, rather than having to use callbacks.

This will allow you to follow the same pattern you have in other parts of your code with code such as...

  const confirm = await ui.confirm('Are you sure you want to do this?');

    alert('yes clicked');
  } else{
    alert('no clicked');

See codepen for example, or run the snippet below.

enter image description here

const ui = {_x000D_
  confirm: async (message) => createConfirm(message)_x000D_
const createConfirm = (message) => {_x000D_
  return new Promise((complete, failed)=>{_x000D_
    $('#confirmYes').on('click', ()=> { $('.confirm').hide(); complete(true); });_x000D_
    $('#confirmNo').on('click', ()=> { $('.confirm').hide(); complete(false); });_x000D_
const saveForm = async () => {_x000D_
  const confirm = await ui.confirm('Are you sure you want to do this?');_x000D_
    alert('yes clicked');_x000D_
  } else{_x000D_
    alert('no clicked');_x000D_
body {_x000D_
  margin: 0px;_x000D_
  font-family: "Arial";_x000D_
.example {_x000D_
  padding: 20px;_x000D_
input[type=button] {_x000D_
  padding: 5px 10px;_x000D_
  margin: 10px 5px;_x000D_
  border-radius: 5px;_x000D_
  cursor: pointer;_x000D_
  background: #ddd;_x000D_
  border: 1px solid #ccc;_x000D_
input[type=button]:hover {_x000D_
  background: #ccc;_x000D_
.confirm {_x000D_
  display: none;_x000D_
.confirm > div:first-of-type {_x000D_
  position: fixed;_x000D_
  width: 100%;_x000D_
  height: 100%;_x000D_
  background: rgba(0, 0, 0, 0.5);_x000D_
  top: 0px;_x000D_
  left: 0px;_x000D_
.confirm > div:last-of-type {_x000D_
  padding: 10px 20px;_x000D_
  background: white;_x000D_
  position: absolute;_x000D_
  width: auto;_x000D_
  height: auto;_x000D_
  left: 50%;_x000D_
  top: 50%;_x000D_
  transform: translate(-50%, -50%);_x000D_
  border-radius: 5px;_x000D_
  border: 1px solid #333;_x000D_
.confirm > div:last-of-type div:first-of-type {_x000D_
  min-width: 150px;_x000D_
  padding: 10px;_x000D_
.confirm > div:last-of-type div:last-of-type {_x000D_
  text-align: right;_x000D_
<script src=""></script>_x000D_
<div class="example">_x000D_
  <input type="button" onclick="saveForm()" value="Save" />_x000D_
<!-- Hidden confirm markup somewhere at the bottom of page -->_x000D_
<div class="confirm">_x000D_
    <div id="confirmMessage"></div>_x000D_
      <input id="confirmYes" type="button" value="Yes" />_x000D_
      <input id="confirmNo" type="button" value="No" />_x000D_

Ansible: create a user with sudo privileges

Sometimes it's knowing what to ask. I didn't know as I am a developer who has taken on some DevOps work.

Apparently 'passwordless' or NOPASSWD login is a thing which you need to put in the /etc/sudoers file.

The answer to my question is at Ansible: best practice for maintaining list of sudoers.

The Ansible playbook code fragment looks like this from my problem:

- name: Make sure we have a 'wheel' group
    name: wheel
    state: present

- name: Allow 'wheel' group to have passwordless sudo
    dest: /etc/sudoers
    state: present
    regexp: '^%wheel'
    line: '%wheel ALL=(ALL) NOPASSWD: ALL'
    validate: 'visudo -cf %s'

- name: Add sudoers users to wheel group

- name: Set up authorized keys for the deployer user
  authorized_key: user=deployer key="{{item}}"
    - /home/railsdev/.ssh/

And the best part is that the solution is idempotent. It doesn't add the line


to /etc/sudoers when the playbook is run a subsequent time. And yes...I was able to ssh into the server as "deployer" and run sudo commands without having to give a password.

How to compile the finished C# project and then run outside Visual Studio?

In the project file is folder "bin/debug/your_appliacion_name.exe". This is final executable program file.

jquery select option click handler

The problem that I had with the change handler was that it triggered on every keypress that I scrolled up and down the <select>.

I wanted to get the event for whenever an option was clicked or when enter was pressed on the desired option. This is how I ended up doing it:

let blockChange = false;

$element.keydown(function (e) {

    const keycode = (e.keyCode ? e.keyCode : e.which);

    // prevents select opening when enter is pressed
    if (keycode === 13) {

    // lets the change event know that these keypresses are to be ignored
    if([38, 40].indexOf(keycode) > -1){
        blockChange = true;


$element.keyup(function(e) {

    const keycode = (e.keyCode ? e.keyCode : e.which);
    // handle enter press
    if(keycode === 13) {


$element.change(function(e) {

    // this effective handles the click only as preventDefault was used on enter
    if(!blockChange) {
    blockChange = false;


Getting The ASCII Value of a character in a C# string

Here is another alternative. It will of course give you a bad result if the input char is not ascii. I've not perf tested it but I think it would be pretty fast:

private static int GetAsciiVal(string s, int index) {
    return GetAsciiVal(s[index]);

private static int GetAsciiVal(char c) {
    return unchecked(c & 0xFF);

How to make ConstraintLayout work with percentage values?

With the ConstraintLayout v1.1.2, the dimension should be set to 0dp and then set the layout_constraintWidth_percent or layout_constraintHeight_percent attributes to a value between 0 and 1 like :

<!-- 50% width centered Button -->
    app:layout_constraintWidth_percent=".5" />

(You don't need to set app:layout_constraintWidth_default="percent" or app:layout_constraintHeight_default="percent" with ConstraintLayout 1.1.2 and following versions)

How to access share folder in virtualbox. Host Win7, Guest Fedora 16?

May be this can help other guys: I had the same problem, and after looking with Google I found that can be because of the permissions of the folder... So, you need first to add permissions...

$ chmod 777 share_folder

Then run again

$ sudo mount -t vboxsf D:\share_folder_vm \share_folder

Check the answers here: Error mounting VirtualBox shared folders in an Ubuntu guest...

How to remove the last element added into the List?

The direct answer to this question is:

if(rows.Any()) //prevent IndexOutOfRangeException for empty list
    rows.RemoveAt(rows.Count - 1);

However... in the specific case of this question, it makes more sense not to add the row in the first place:

Row row = new Row();

if (!row.cell[0].Equals("Something"))

TBH, I'd go a step further by testing "Something" against user."", and not even instantiating a Row unless the condition is satisfied, but seeing as user."" won't compile, I'll leave that as an exercise for the reader.

What's the PowerShell syntax for multiple values in a switch statement?

You should be able to use a wildcard for your values:

switch -wildcard ($someString.ToLower())
    "y*" { "You entered Yes." }
    default { "You entered No." }

Regular expressions are also allowed.

switch -regex ($someString.ToLower())
    "y(es)?" { "You entered Yes." }
    default { "You entered No." }

PowerShell switch documentation: Using the Switch Statement

Recommended SQL database design for tags or tagging

I've always kept the tags in a separate table and then had a mapping table. Of course I've never done anything on a really large scale either.

Having a "tags" table and a map table makes it pretty trivial to generate tag clouds & such since you can easily put together SQL to get a list of tags with counts of how often each tag is used.

Generate a random letter in Python

All previous answers are correct, if you are looking for random characters of various types (i.e. alphanumeric and special characters) then here is an script that I created to demonstrate various types of creating random functions, it has three functions one for numbers, alpha- characters and special characters. The script simply generates passwords and is just an example to demonstrate various ways of generating random characters.

import string
import random
import sys

#make sure it's 3.7 or above

def create_str(str_length):
    return random.sample(string.ascii_letters, str_length)

def create_num(num_length):
    digits = []
    for i in range(num_length):
        digits.append(str(random.randint(1, 100)))

    return digits

def create_special_chars(special_length):
    stringSpecial = []
    for i in range(special_length):

    return stringSpecial

print("how many characters would you like to use ? (DO NOT USE LESS THAN 8)")
str_cnt = input()
print("how many digits would you like to use ? (DO NOT USE LESS THAN 2)")
num_cnt = input()
print("how many special characters would you like to use ? (DO NOT USE LESS THAN 1)")
s_chars_cnt = input()
password_values = create_str(int(str_cnt)) +create_num(int(num_cnt)) + create_special_chars(int(s_chars_cnt))

#shuffle/mix the values

print("generated password is: ")


enter image description here

Failed Apache2 start, no error log

On XAMPP use

D:\xampp\apache\bin>httpd -t -D DUMP_VHOSTS

This will yield errors in your configuration of the virtual hosts

GDB: Listing all mapped memory regions for a crashed process

In GDB 7.2:

(gdb) help info proc
Show /proc process information about any running process.
Specify any process id, or use the program being debugged by default.
Specify any of the following keywords for detailed info:
  mappings -- list of mapped memory regions.
  stat     -- list a bunch of random process info.
  status   -- list a different bunch of random process info.
  all      -- list all available /proc info.

You want info proc mappings, except it doesn't work when there is no /proc (such as during pos-mortem debugging).

Try maintenance info sections instead.

ASP.NET Web Site or ASP.NET Web Application?

WebSite : It generates app_code folder automatically and if you publish it on the server and after that if you do some changes in any particular file or page than you don't have to do compile all files.

Web Application It generates solutions file automatically which website doesn't generate and if you change in one file than you have to compile full project to reflects its changes.

How can I remove the last character of a string in python?

As you say, you don't need to use a regex for this. You can use rstrip.

my_file_path = my_file_path.rstrip('/')

If there is more than one / at the end, this will remove all of them, e.g. '/file.jpg//' -> '/file.jpg'. From your question, I assume that would be ok.

onchange event for input type="number"

$(':input').bind('click keyup', function(){
    // do stuff


How do you normalize a file path in Bash?

I discovered today that you can use the stat command to resolve paths.

So for a directory like "~/Documents":

You can run this:

stat -f %N ~/Documents

To get the full path:


For symlinks, you can use the %Y format option:

stat -f %Y example_symlink

Which might return a result like:


The formatting options might be different on other versions of *NIX but these worked for me on OSX.

How can I add a username and password to Jenkins?

Go to Manage Jenkins > Configure Global Security and select the Enable Security checkbox.

For the basic username/password authentication, I would recommend selecting Jenkins Own User Database for the security realm and then selecting Logged in Users can do anything or a matrix based strategy (in case when you have multiple users with different permissions) for the Authorization.

LINQ: Select where object does not contain items from list

dump this into a more specific collection of just the ids you don't want

var notTheseBarIds = filterBars.Select(fb => fb.BarId);

then try this:

fooSelect = (from f in fooBunch
             where !notTheseBarIds.Contains(f.BarId)
             select f).ToList();

or this:

fooSelect = fooBunch.Where(f => !notTheseBarIds.Contains(f.BarId)).ToList();

how to use javascript Object.defineProperty

defineProperty is a method on Object which allow you to configure the properties to meet some criterias. Here is a simple example with an employee object with two properties firstName & lastName and append the two properties by overriding the toString method on the object.

var employee = {
    firstName: "Jameel",
    lastName: "Moideen"
employee.toString=function () {
    return this.firstName + " " + this.lastName;

You will get Output as : Jameel Moideen

I am going to change the same code by using defineProperty on the object

var employee = {
    firstName: "Jameel",
    lastName: "Moideen"
Object.defineProperty(employee, 'toString', {
    value: function () {
        return this.firstName + " " + this.lastName;
    writable: true,
    enumerable: true,
    configurable: true

The first parameter is the name of the object and then second parameter is name of the property we are adding , in our case it’s toString and then the last parameter is json object which have a value going to be a function and three parameters writable,enumerable and configurable.Right now I just declared everything as true.

If u run the example you will get Output as : Jameel Moideen

Let’s understand why we need the three properties such as writable,enumerable and configurable.


One of the very annoying part of the javascript is , if you change the toString property to something else for example

enter image description here

if you run this again , everything gets breaks. Let’s change writable to false. If run the same again you will get the correct output as ‘Jameel Moideen’ . This property will prevent overwrite this property later.


if you print all the keys inside the object , you can see all the properties including toString.


enter image description here

if you set enumerable to false , you can hide toString property from everybody else. If run this again you will get firstName,lastName


if someone later redefined the object on later for example enumerable to true and run it. You can see toString property came again.

var employee = {
    firstName: "Jameel",
    lastName: "Moideen"
Object.defineProperty(employee, 'toString', {
    value: function () {
        return this.firstName + " " + this.lastName;
    writable: false,
    enumerable: false,
    configurable: true

//change enumerable to false
Object.defineProperty(employee, 'toString', {

    enumerable: true

enter image description here

you can restrict this behavior by set configurable to false.

Orginal reference of this information is from my personal Blog

Remove the last character from a string

You can use

substr(string $string, int $start, int[optional] $length=null);

See substr in the PHP documentation. It returns part of a string.

how to compare the Java Byte[] array?

Cause they're not equal, ie: they're different arrays with equal elements inside.

Try using Arrays.equals() or Arrays.deepEquals().

How to redirect in a servlet filter?

Try and check of your ServletResponse response is an instanceof HttpServletResponse like so:

if (response instanceof HttpServletResponse) {

Oracle PL Sql Developer cannot find my tnsnames.ora file

I had the same problema, but as described in the manual.pdf, you have to:

You are using an Oracle Instant Client but have not set all required environment variables:

  • PATH: Needs to include the Instant Client directory where oci.dll is located
  • TNS_ADMIN: Needs to point to the directory where tnsnames.ora is located.
  • NLS_LANG: Defines the language, territory, and character set for the client.


How to deal with a slow SecureRandom generator?

If your hardware supports it try using Java RdRand Utility of which I'm the author.

Its based on Intel's RDRAND instruction and is about 10 times faster than SecureRandom and no bandwidth issues for large volume implementation.

Note that this implementation only works on those CPU's that provide the instruction (i.e. when the rdrand processor flag is set). You need to explicitly instantiate it through the RdRandRandom() constructor; no specific Provider has been implemented.

XPath:: Get following Sibling


In Chrome (possible Safari too) you can inspect an element, then right click on the tag you want to get the xpath for, then you can copy the xpath to select that element.

How to unzip a file in Powershell?

Use Expand-Archive cmdlet with one of parameter set:

Expand-Archive -LiteralPath C:\source\file.Zip -DestinationPath C:\destination
Expand-Archive -Path file.Zip -DestinationPath C:\destination

Adding Multiple Values in ArrayList at a single index

@Ahamed has a point, but if you're insisting on using lists so you can have three arraylist like this:

ArrayList<Integer> first = new ArrayList<Integer>(Arrays.AsList(100,100,100,100,100));
ArrayList<Integer> second = new ArrayList<Integer>(Arrays.AsList(50,35,25,45,65));
ArrayList<Integer> third = new ArrayList<Integer>();

for(int i = 0; i < first.size(); i++) {

Edit: If you have those values on your list that below:

List<double[]> values = new ArrayList<double[]>(2);

what you want to do is combine them, right? You can try something like this: (I assume that both array are same sized, otherwise you need to use two for statement)

ArrayList<Double> yourArray = new ArrayList<Double>();
for(int i = 0; i < values.get(0).length; i++) {

No Main class found in NetBeans

if all that is your code you forgot to close the main method

everything else sounds good to me

public class LuisRp3 {

public static void main(String[] args) throws FileNotFoundException  { newFile = new"LuisRamosp4.txt");

    if (newFile.exists()) {

    System.setOut(new PrintStream(newFile));

    Guitar guitar = new Guitar(); 

try that

How to measure the a time-span in seconds using System.currentTimeMillis()?

I have written the following code in my last assignment, it may help you:

// A method that converts the nano-seconds to Seconds-Minutes-Hours form
private static String formatTime(long nanoSeconds)
    int hours, minutes, remainder, totalSecondsNoFraction;
    double totalSeconds, seconds;

    // Calculating hours, minutes and seconds
    totalSeconds = (double) nanoSeconds / 1000000000.0;
    String s = Double.toString(totalSeconds);
    String [] arr = s.split("\\.");
    totalSecondsNoFraction = Integer.parseInt(arr[0]);
    hours = totalSecondsNoFraction / 3600;
    remainder = totalSecondsNoFraction % 3600;
    minutes = remainder / 60;
    seconds = remainder % 60;
    if(arr[1].contains("E")) seconds = Double.parseDouble("." + arr[1]);
    else seconds += Double.parseDouble("." + arr[1]);

    // Formatting the string that conatins hours, minutes and seconds
    StringBuilder result = new StringBuilder(".");
    String sep = "", nextSep = " and ";
    if(seconds > 0)
        result.insert(0, " seconds").insert(0, seconds);
        sep = nextSep;
        nextSep = ", ";
    if(minutes > 0)
        if(minutes > 1) result.insert(0, sep).insert(0, " minutes").insert(0, minutes);
        else result.insert(0, sep).insert(0, " minute").insert(0, minutes);
        sep = nextSep;
        nextSep = ", ";
    if(hours > 0)
        if(hours > 1) result.insert(0, sep).insert(0, " hours").insert(0, hours);
        else result.insert(0, sep).insert(0, " hour").insert(0, hours);
    return result.toString();

Just convert nano-seconds to milli-seconds.

Making an array of integers in iOS

I created a simple Objective C wrapper around the good old C array to be used more conveniently:

How do I install PyCrypto on Windows?

If you don't already have a C/C++ development environment installed that is compatible with the Visual Studio binaries distributed by, then you should stick to installing only pure Python packages or packages for which a Windows binary is available.

Fortunately, there are PyCrypto binaries available for Windows:

As @Udi suggests in the comment below, the following command also installs pycrypto and can be used in virtualenv as well:


Notice to choose the relevant link for your setup from this list

If you're looking for builds for Python 3.5, see PyCrypto on python 3.5

How do you get the list of targets in a makefile?

Yet another additional answer to above.

tested on MacOSX using only cat and awk on terminal

cat Makefile | awk '!/SHELL/ && /^[A-z]/ {print $1}' | awk '{print substr($0, 1, length($0)-1)}'

will output of the make file like below:




in the Makefile, it should be the same statement, ensure that you escape the variables using $$variable rather than $variable.


cat - spits out the contents

| - pipe parses output to next awk

awk - runs regex excluding "shell" and accepting only "A-z" lines then prints out the $1 first column

awk - yet again removes the last character ":" from the list

this is a rough output and you can do more funky stuff with just AWK. Try to avoid sed as its not as consistent in BSDs variants i.e. some works on *nix but fails on BSDs like MacOSX.


You should be able add this (with modifications) to a file for make, to the default bash-completion folder /usr/local/etc/bash-completion.d/ meaning when you "make tab tab" .. it will complete the targets based on the one liner script.

Whats the CSS to make something go to the next line in the page?

Have the element display as a block:

display: block;

lvalue required as left operand of assignment error when using C++

if you use an assignment operator but use it in wrong way or in wrong place, then you'll get this types of errors!

suppose if you type:
p+1=p; you will get the error!!

you will get the same error for this:
if(ch>='a' && ch='z')
as you see can see that I i tried to assign in if() statement!!!
how silly I am!!! right??
ha ha
actually i forgot to give less then(<) sign
if(ch>='a' && ch<='z')
and got the error!!

Center content vertically on Vuetify

Here's another approach using Vuetify grid system available in Vuetify 2.x:

    <v-row align="center">
        Hello I am center to vertically using "grid".

How to properly make a http web GET request

Simpliest way for my opinion

  var web = new WebClient();
  var url = $"{hostname}/LoadDataSync?systemID={systemId}";
  var responseString = web.DownloadString(url);


 var bytes = web.DownloadData(url);

In AVD emulator how to see sdcard folder? and Install apk to AVD?

  1. switch to DDMS perspective
  2. select the emulator in devices list, whose sdcard you want to explore.
  3. open File Explorer tab on right hand side.
  4. expand tree structure. mnt/sdcard/

refer to image belowenter image description here

To install apk manually: copy your apk to to sdk/platform-tools folder and run following command in the same folder

adb install apklocation.apk

PL/SQL ORA-01422: exact fetch returns more than requested number of rows

A SELECT INTO statement will throw an error if it returns anything other than 1 row. If it returns 0 rows, you'll get a no_data_found exception. If it returns more than 1 row, you'll get a too_many_rows exception. Unless you know that there will always be exactly 1 employee with a salary greater than 3000, you do not want a SELECT INTO statement here.

Most likely, you want to use a cursor to iterate over (potentially) multiple rows of data (I'm also assuming that you intended to do a proper join between the two tables rather than doing a Cartesian product so I'm assuming that there is a departmentID column in both tables)

                FROM EMPLOYEE, 
               WHERE employee.departmentID = department.departmentID
                 AND EMPLOYEE.SALARY > 3000)
    DBMS_OUTPUT.PUT_LINE ('Employee Nnumber: ' || rec.EMPID);
    DBMS_OUTPUT.PUT_LINE ('---------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Name: ' || rec.ENAME);
    DBMS_OUTPUT.PUT_LINE ('---------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Designation: ' || rec.DESIGNATION);
    DBMS_OUTPUT.PUT_LINE ('----------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Salary: ' || rec.SALARY);
    DBMS_OUTPUT.PUT_LINE ('----------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Department: ' || rec.DEPT_NAME);

I'm assuming that you are just learning PL/SQL as well. In real code, you'd never use dbms_output like this and would not depend on anyone seeing data that you write to the dbms_output buffer.

Which Architecture patterns are used on Android?

enter image description here

When i reach this post it really help me to understand patterns with example so i have make below table to clearly see the Design patterns & their example in Android Framework

I hope you will find it helpful.

How to part DATE and TIME from DATETIME in MySQL

You can achieve that using DATE_FORMAT() (click the link for more other formats)

       DATE_FORMAT(colName,'%H:%i:%s') TIMEONLY

SQLFiddle Demo

Maximum number of threads in a .NET app?

i did a test on a 64bit system with c# console, the exception is type of out of memory, using 2949 threads.

I realize we should be using threading pool, which I do, but this answer is in response to the main question ;)

How to activate virtualenv?

instead of ./activate

use source activate

See this screenshot

The best way to calculate the height in a binary search tree? (balancing an AVL-tree)

Well, you can compute the height of a tree with the following recursive function:

int height(struct tree *t) {
    if (t == NULL)
        return 0;
        return max(height(t->left), height(t->right)) + 1;

with an appropriate definition of max() and struct tree. You should take the time to figure out why this corresponds to the definition based on path-length that you quote. This function uses zero as the height of the empty tree.

However, for something like an AVL tree, I don't think you actually compute the height each time you need it. Instead, each tree node is augmented with a extra field that remembers the height of the subtree rooted at that node. This field has to be kept up-to-date as the tree is modified by insertions and deletions.

I suspect that, if you compute the height each time instead of caching it within the tree like suggested above, that the AVL tree shape will be correct, but it won't have the expected logarithmic performance.

100% width in React Native Flexbox

Here you go:

Just change the line1 style as per below:

line1: {
    backgroundColor: '#FDD7E4',

jquery - is not a function error

This problem is "best" solved by using an anonymous function to pass-in the jQuery object thusly:

The Anonymous Function Looks Like:

<script type="text/javascript">
    (function($) {
        // You pass-in jQuery and then alias it with the $-sign
        // So your internal code doesn't change

This is JavaScript's method of implementing (poor man's) 'Dependency Injection' when used alongside things like the 'Module Pattern'.

So Your Code Would Look Like:
Of course, you might want to make some changes to your internal code now, but you get the idea.

<script type="text/javascript">
    (function($) {
        $.fn.pluginbutton = function(options) {
            myoptions = $.extend({ left: true });
            return this.each(function() {
                var focus = false;
                if (focus === false) {
                    this.hover(function() {
                        this.animate({ backgroundPosition: "0 -30px" }, { duration: 0 });
                    }, function() {
                        this.animate({ backgroundPosition: "0 0" }, { duration: 0 });
                this.mousedown(function() {
                    focus = true
                    this.animate({ backgroundPosition: "0 30px" }, { duration: 0 });
                }, function() {
                    focus = false;
                    this.animate({ backgroundPosition: "0 0" }, { duration: 0 });

How can I query a value in SQL Server XML column

if your field name is Roles and table name is table1 you can use following to search

DECLARE @Role varchar(50);
SELECT * FROM table1
WHERE Roles.exist ('/root/role = sql:variable("@Role")') = 1

ipad safari: disable scrolling, and bounce effect?

overflow: scroll;
-webkit-overflow-scrolling: touch;

On container you can set bounce effect inside element