Programs & Examples On #Generic variance

Generic variance is the ability to assign a generic interface or delegate type to the same type with another parameter, for example, assign IEnumerable to IEnumerable. Generic variance has to be defined on the generic parameter type that supports them. There are two kinds of generic variance, covariance and contravariance.

How to sort an ArrayList?

With Java8 there is a default sort method on the List interface that will allow you to sort the collection if you provide a Comparator. You can easily sort the example in the question as follows:

testList.sort((a, b) -> Double.compare(b, a));

Note: the args in the lambda are swapped when passed in to Double.compare to ensure the sort is descending

What is String pool in Java?

Let's start with a quote from the virtual machine spec:

Loading of a class or interface that contains a String literal may create a new String object (§2.4.8) to represent that literal. This may not occur if the a String object has already been created to represent a previous occurrence of that literal, or if the String.intern method has been invoked on a String object representing the same string as the literal.

This may not occur - This is a hint, that there's something special about String objects. Usually, invoking a constructor will always create a new instance of the class. This is not the case with Strings, especially when String objects are 'created' with literals. Those Strings are stored in a global store (pool) - or at least the references are kept in a pool, and whenever a new instance of an already known Strings is needed, the vm returns a reference to the object from the pool. In pseudo code, it may go like that:

1: a := "one" 
   --> if(pool[hash("one")] == null)  // true
           pool[hash("one") --> "one"]
       return pool[hash("one")]

2: b := "one" 
  --> if(pool[hash("one")] == null)   // false, "one" already in pool
        pool[hash("one") --> "one"]
      return pool[hash("one")] 

So in this case, variables a and b hold references to the same object. IN this case, we have (a == b) && (a.equals(b)) == true.

This is not the case if we use the constructor:

1: a := "one"
2: b := new String("one")

Again, "one" is created on the pool but then we create a new instance from the same literal, and in this case, it leads to (a == b) && (a.equals(b)) == false

So why do we have a String pool? Strings and especially String literals are widely used in typical Java code. And they are immutable. And being immutable allowed to cache String to save memory and increase performance (less effort for creation, less garbage to be collected).

As programmers we don't have to care much about the String pool, as long as we keep in mind:

  • (a == b) && (a.equals(b)) may be true or false (always use equals to compare Strings)
  • Don't use reflection to change the backing char[] of a String (as you don't know who is actualling using that String)

Foreign keys in mongo?

How to design table like this in mongodb?

First, to clarify some naming conventions. MongoDB uses collections instead of tables.

I think there are no foreign keys!

Take the following model:

student
{ 
  _id: ObjectId(...),
  name: 'Jane',
  courses: [
    { course: 'bio101', mark: 85 },
    { course: 'chem101', mark: 89 }
  ]
}

course
{
  _id: 'bio101',
  name: 'Biology 101',
  description: 'Introduction to biology'
}

Clearly Jane's course list points to some specific courses. The database does not apply any constraints to the system (i.e.: foreign key constraints), so there are no "cascading deletes" or "cascading updates". However, the database does contain the correct information.

In addition, MongoDB has a DBRef standard that helps standardize the creation of these references. In fact, if you take a look at that link, it has a similar example.

How can I solve this task?

To be clear, MongoDB is not relational. There is no standard "normal form". You should model your database appropriate to the data you store and the queries you intend to run.

Call to a member function on a non-object

It could also mean that when you initialized your object, you may have re-used the object name in another part of your code. Therefore changing it's aspect from an object to a standard variable.

IE

$game = new game;

$game->doGameStuff($gameReturn);

foreach($gameArray as $game)
{
   $game['STUFF']; // No longer an object and is now a standard variable pointer for $game.
}



$game->doGameStuff($gameReturn);  // Wont work because $game is declared as a standard variable.  You need to be careful when using common variable names and were they are declared in your code.

CSS: how do I create a gap between rows in a table?

If you don't have borders, or have borders and want the spacing inside the cells, you can use padding, or line-height. As far as I know, margin has no effect on cells and rows.
A CSS property for spacing of cells is border-spacing, but it doesn't work on IE6/7 (so you can use it depending on your crowd).

If all else fails you can use the old cellspacing attribute in your markup - but this will also give you spacing between the columns. Some CSS reset suggest you should set it anyway to get cross-browser support:

/* tables still need cellspacing="0" in the markup */

Show data on mouseover of circle

This concise example demonstrates common way how to create custom tooltip in d3.

_x000D_
_x000D_
var w = 500;_x000D_
var h = 150;_x000D_
_x000D_
var dataset = [5, 10, 15, 20, 25];_x000D_
_x000D_
// firstly we create div element that we can use as_x000D_
// tooltip container, it have absolute position and_x000D_
// visibility: hidden by default_x000D_
_x000D_
var tooltip = d3.select("body")_x000D_
  .append("div")_x000D_
  .attr('class', 'tooltip');_x000D_
_x000D_
var svg = d3.select("body")_x000D_
  .append("svg")_x000D_
  .attr("width", w)_x000D_
  .attr("height", h);_x000D_
_x000D_
// here we add some circles on the page_x000D_
_x000D_
var circles = svg.selectAll("circle")_x000D_
  .data(dataset)_x000D_
  .enter()_x000D_
  .append("circle");_x000D_
_x000D_
circles.attr("cx", function(d, i) {_x000D_
    return (i * 50) + 25;_x000D_
  })_x000D_
  .attr("cy", h / 2)_x000D_
  .attr("r", function(d) {_x000D_
    return d;_x000D_
  })_x000D_
  _x000D_
  // we define "mouseover" handler, here we change tooltip_x000D_
  // visibility to "visible" and add appropriate test_x000D_
  _x000D_
  .on("mouseover", function(d) {_x000D_
    return tooltip.style("visibility", "visible").text('radius = ' + d);_x000D_
  })_x000D_
  _x000D_
  // we move tooltip during of "mousemove"_x000D_
  _x000D_
  .on("mousemove", function() {_x000D_
    return tooltip.style("top", (event.pageY - 30) + "px")_x000D_
      .style("left", event.pageX + "px");_x000D_
  })_x000D_
  _x000D_
  // we hide our tooltip on "mouseout"_x000D_
  _x000D_
  .on("mouseout", function() {_x000D_
    return tooltip.style("visibility", "hidden");_x000D_
  });
_x000D_
.tooltip {_x000D_
    position: absolute;_x000D_
    z-index: 10;_x000D_
    visibility: hidden;_x000D_
    background-color: lightblue;_x000D_
    text-align: center;_x000D_
    padding: 4px;_x000D_
    border-radius: 4px;_x000D_
    font-weight: bold;_x000D_
    color: orange;_x000D_
}
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.11.0/d3.min.js"></script>
_x000D_
_x000D_
_x000D_

Git: which is the default configured remote for branch?

For the sake of completeness: the previous answers tell how to set the upstream branch, but not how to see it.

There are a few ways to do this:

git branch -vv shows that info for all branches. (formatted in blue in most terminals)

cat .git/config shows this also.

For reference:

Add jars to a Spark Job - spark-submit

When using spark-submit with --master yarn-cluster, the application jar along with any jars included with the --jars option will be automatically transferred to the cluster. URLs supplied after --jars must be separated by commas. That list is included in the driver and executor classpaths

Example :

spark-submit --master yarn-cluster --jars ../lib/misc.jar, ../lib/test.jar --class MainClass MainApp.jar

https://spark.apache.org/docs/latest/submitting-applications.html

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!)

https://www.youtube.com/watch?v=gDzAm25CORk

Then go to jupyter notebook and code

!pip install tensorflow

Then

import tensorflow as tf

It work for me! :)

How to make in CSS an overlay over an image?

You could use a pseudo element for this, and have your image on a hover:

_x000D_
_x000D_
.image {_x000D_
  position: relative;_x000D_
  height: 300px;_x000D_
  width: 300px;_x000D_
  background: url(http://lorempixel.com/300/300);_x000D_
}_x000D_
.image:before {_x000D_
  content: "";_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  height: 100%;_x000D_
  width: 100%;_x000D_
  transition: all 0.8s;_x000D_
  opacity: 0;_x000D_
  background: url(http://lorempixel.com/300/200);_x000D_
  background-size: 100% 100%;_x000D_
}_x000D_
.image:hover:before {_x000D_
  opacity: 0.8;_x000D_
}
_x000D_
<div class="image"></div>
_x000D_
_x000D_
_x000D_

Delete/Reset all entries in Core Data?

iOS 10 and Swift 3

Assuming that your entity name is "Photo", and that you create a CoreDataStack class...

 func clearData() {
        do {            
            let context = CoreDataStack.sharedInstance.persistentContainer.viewContext
            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Photo")
            do {
                let objects  = try context.fetch(fetchRequest) as? [NSManagedObject]
                _ = objects.map{$0.map{context.delete($0)}}
                CoreDataStack.sharedInstance.saveContext()
            } catch let error {
                print("ERROR DELETING : \(error)")
            }
        }
    }

Here is a good tutorial of how to use CoreData and how to use this method. https://medium.com/compileswift/parsing-json-response-and-save-it-in-coredata-step-by-step-fb58fc6ce16f#.1tu6kt8qb

How do I compare two columns for equality in SQL Server?

What's wrong with CASE for this? In order to see the result, you'll need at least a byte, and that's what you get with a single character.

CASE WHEN COLUMN1 = COLUMN2 THEN '1' ELSE '0' END AS MyDesiredResult

should work fine, and for all intents and purposes accomplishes the same thing as using a bit field.

How to build x86 and/or x64 on Windows from command line with CMAKE?

Besides CMAKE_GENERATOR_PLATFORM variable, there is also the -A switch

cmake -G "Visual Studio 16 2019" -A Win32
cmake -G "Visual Studio 16 2019" -A x64

https://cmake.org/cmake/help/v3.16/generator/Visual%20Studio%2016%202019.html#platform-selection

  -A <platform-name>           = Specify platform name if supported by
                                 generator.

How do I configure IIS for URL Rewriting an AngularJS application in HTML5 mode?

The easiest way I found is just to redirect the requests that trigger 404 to the client. This is done by adding an hashtag even when $locationProvider.html5Mode(true) is set.

This trick works for environments with more Web Application on the same Web Site and requiring URL integrity constraints (E.G. external authentication). Here is step by step how to do

index.html

Set the <base> element properly

<base href="@(Request.ApplicationPath + "/")">

web.config

First redirect 404 to a custom page, for example "Home/Error"

<system.web>
    <customErrors mode="On">
        <error statusCode="404" redirect="~/Home/Error" />
    </customErrors>
</system.web>

Home controller

Implement a simple ActionResult to "translate" input in a clientside route.

public ActionResult Error(string aspxerrorpath) {
    return this.Redirect("~/#/" + aspxerrorpath);
}

This is the simplest way.


It is possible (advisable?) to enhance the Error function with some improved logic to redirect 404 to client only when url is valid and let the 404 trigger normally when nothing will be found on client. Let's say you have these angular routes

.when("/", {
    templateUrl: "Base/Home",
    controller: "controllerHome"
})
.when("/New", {
    templateUrl: "Base/New",
    controller: "controllerNew"
})
.when("/Show/:title", {
    templateUrl: "Base/Show",
    controller: "controllerShow"
})

It makes sense to redirect URL to client only when it start with "/New" or "/Show/"

public ActionResult Error(string aspxerrorpath) {
    // get clientside route path
    string clientPath = aspxerrorpath.Substring(Request.ApplicationPath.Length);

    // create a set of valid clientside path
    string[] validPaths = { "/New", "/Show/" };

    // check if clientPath is valid and redirect properly
    foreach (string validPath in validPaths) {
        if (clientPath.StartsWith(validPath)) {
            return this.Redirect("~/#/" + clientPath);
        }
    }

    return new HttpNotFoundResult();
}

This is just an example of improved logic, of course every web application has different needs

Best timestamp format for CSV/Excel?

The earlier suggestion to use "yyyy-MM-dd HH:mm:ss" is fine, though I believe Excel has much finer time resolution than that. I find this post rather credible (follow the thread and you'll see lots of arithmetic and experimenting with Excel), and if it's correct, you'll have your milliseconds. You can just tack on decimal places at the end, i.e. "yyyy-mm-dd hh:mm:ss.000".

You should be aware that Excel may not necessarily format the data (without human intervention) in such a way that you will see all of that precision. On my computer at work, when I set up a CSV with "yyyy-mm-dd hh:mm:ss.000" data (by hand using Notepad), I get "mm:ss.0" in the cell and "m/d/yyyy  hh:mm:ss AM/PM" in the formula bar.

For maximum information[1] conveyed in the cells without human intervention, you may want to split up your timestamp into a date portion and a time portion, with the time portion only to the second. It looks to me like Excel wants to give you at most three visible "levels" (where fractions of a second are their own level) in any given cell, and you want seven: years, months, days, hours, minutes, seconds, and fractions of a second.

Or, if you don't need the timestamp to be human-readable but you want it to be as accurate as possible, you might prefer just to store a big number (internally, Excel is just using the number of days, including fractional days, since an "epoch" date).


[1]That is, numeric information. If you want to see as much information as possible but don't care about doing calculations with it, you could make up some format which Excel will definitely parse as a string, and thus leave alone; e.g. "yyyymmdd.hhmmss.000".

How much does it cost to develop an iPhone application?

The rates that were quoted above are what you would expect to pay US developers; however, I do know some people who have been able to get their apps built for as little as $4,000 by using offshore developers.

Here is a blog post from a group that did this: http://www.lolerapps.com/why-outsourcing-iphone-apps-was-a-no-brainer-for-us

Also, Carla White wrote a fantastic eBook about the process she used to outsource her app called "Inside Secrets to an iPhone App". She talks about how she got a great deal because she was willing to work with a team that was still learning iPhone app development.

So, there are alternatives to the higher price developers discussed above.

Specifying trust store information in spring boot application.properties

java properties "javax.net.ssl.trustStore" and "javax.net.ssl.trustStorePassword" do not correspond to "server.ssl.trust-store" and "server.ssl.trust-store-password" from Spring boot "application.properties" ("application.yml")

so you can not set "javax.net.ssl.trustStore" and "javax.net.ssl.trustStorePassword" simply by setting "server.ssl.trust-store" and "server.ssl.trust-store-password" in "application.properties" ("application.yml")

an alternative of setting "javax.net.ssl.trustStore" and "javax.net.ssl.trustStorePassword" is by Spring boot Externalized Configuration

below are excerpts of my implementation :

Params class holds the external settings

@Component
@ConfigurationProperties("params")
public class Params{

    //default values, can be override by external settings
    public static String trustStorePath = "config/client-truststore.jks";
    public static String trustStorePassword = "wso2carbon";
    public static String keyStorePath = "config/wso2carbon.jks";
    public static String keyStorePassword = "wso2carbon";
    public static String defaultType = "JKS";
    
    public void setTrustStorePath(String trustStorePath){
        Params.trustStorePath = trustStorePath;
    }
           
    public void settrustStorePassword(String trustStorePassword){
        Params.trustStorePassword=trustStorePassword;
    }

    public void setKeyStorePath(String keyStorePath){
        Params.keyStorePath = keyStorePath;
    }
         
    public void setkeyStorePassword(String keyStorePassword){
        Params.keyStorePassword = keyStorePassword;
    }
    
    public void setDefaultType(String defaultType){
        Params.defaultType = defaultType;
    }

KeyStoreUtil class undertakes the settings of "javax.net.ssl.trustStore" and "javax.net.ssl.trustStorePassword"

public class KeyStoreUtil {
    
    public static void setTrustStoreParams() {
        File filePath = new File( Params.trustStorePath);
        String tsp = filePath.getAbsolutePath();
        System.setProperty("javax.net.ssl.trustStore", tsp);
        System.setProperty("javax.net.ssl.trustStorePassword", Params.trustStorePassword);
        System.setProperty("javax.net.ssl.keyStoreType", Params.defaultType);

    }

    public static void setKeyStoreParams() {
        File filePath = new File(Params.keyStorePath);
        String ksp = filePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", Params.keyStorePassword);

    }     
}

you get the setters executed within the startup function

@SpringBootApplication
@ComponentScan("com.myapp.profiles")
public class ProfilesApplication {

    public static void main(String[] args) {
        KeyStoreUtil.setKeyStoreParams();
        KeyStoreUtil.setTrustStoreParams();
        SpringApplication.run(ProfilesApplication.class, args);
    }
}

Edited on 2018-10-03

you may also want to adopt the annotation "PostConstruct" as as an alternative to execute the setters

import javax.annotation.PostConstruct;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication(scanBasePackages={"com.xxx"})
public class GateApplication {

    public static void main(String[] args) {
        SpringApplication.run(GateApplication.class, args);
    }
    
    @PostConstruct
    void postConstruct(){
        setTrustStoreParams();
        setKeyStoreParams();
    }
    
    
    private static void setTrustStoreParams() {
        File filePath = new File( Params.trustStorePath);
        String tsp = filePath.getAbsolutePath();
        System.setProperty("javax.net.ssl.trustStore", tsp);
        System.setProperty("javax.net.ssl.trustStorePassword", Params.trustStorePassword);
        System.setProperty("javax.net.ssl.keyStoreType", Params.defaultType);

    }

    private static void setKeyStoreParams() {
        File filePath = new File(Params.keyStorePath);
        String ksp = filePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", Params.keyStorePassword);

    }
}

the application.yml

---
 params: 
   trustStorePath: config/client-truststore.jks
   trustStorePassword: wso2carbon
   keyStorePath: config/wso2carbon.jks
   keyStorePassword: wso2carbon
   defaultType: JKS
---

finally, within the running environment(deployment server), you create a folder named "config" under the same folder where the jar archive is stored .

within the "config" folder, you store "application.yml", "client-truststore.jks", and "wso2carbon.jks". done!

Update on 2018-11-27 about Spring boot 2.x.x

starting from spring boot 2.x.x, static properties are no longer supported, please see here. I personally do not think it a good move, because complex changes have to be made along the reference chain...

anyway, an implementation excerpt might look like this

the 'Params' class

    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.stereotype.Component;
    
    import lombok.Data;
    
    /**
     * Params class represent all config parameters that can 
     * be external set by spring xml file
     */
    
    @Component
    @ConfigurationProperties("params")
    @Data
    public class Params{
    
        //default values, can be override by external settings
        public String trustStorePath = "config/client-truststore.jks";
        public String trustStorePassword = "wso2carbon";
        public String keyStorePath = "config/wso2carbon.jks";
        public String keyStorePassword = "wso2carbon";
        public String defaultType = "JKS";  
}

the 'Springboot application class' (with 'PostConstruct')

import java.io.File;
import javax.annotation.PostConstruct;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication(scanBasePackages={"com.xx.xx"})
public class BillingApplication {
    
    @Autowired
    Params params;
    
    public static void main(String[] args) {
        SpringApplication.run(BillingApplication.class, args);
    }
    
    @PostConstruct
    void postConstruct() {
        
        // set TrustStoreParams
        File trustStoreFilePath = new File(params.trustStorePath);
        String tsp = trustStoreFilePath.getAbsolutePath();
        System.setProperty("javax.net.ssl.trustStore", tsp);
        System.setProperty("javax.net.ssl.trustStorePassword", params.trustStorePassword);
        System.setProperty("javax.net.ssl.keyStoreType", params.defaultType);
        // set KeyStoreParams
        File keyStoreFilePath = new File(params.keyStorePath);
        String ksp = keyStoreFilePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", params.keyStorePassword);
    }
    
}

Open Url in default web browser

In React 16.8+, using functional components, you would do

import React from 'react';
import { Button, Linking } from 'react-native';

const ExternalLinkBtn = (props) => {
  return <Button
            title={props.title}
            onPress={() => {
                Linking.openURL(props.url)
                .catch(err => {
                    console.error("Failed opening page because: ", err)
                    alert('Failed to open page')
                })}}
          />
}

export default function exampleUse() {
  return (
    <View>
      <ExternalLinkBtn title="Example Link" url="https://example.com" />
    </View>
  )
}

Dynamically change color to lighter or darker by percentage CSS (Javascript)

Use the filter pure CSS property. for a complete description of the filter property functions read this awesome article.

I had a same issue like yours, and I fixed it by using the brightness function of filter property:

.my-class {
  background-color: #18d176;
  filter: brightness(90%);
}

window.onunload is not working properly in Chrome browser. Can any one help me?

Armin's answer is so useful, thank you. #2 is what's most important to know when trying to set up unload events that work in most browsers: you cannot alert() or confirm(), but returning a string will generate a confirm modal.

But I found that even with just returning a string, I had some cross-browser issues specific to Mootools (using version 1.4.5 in this instance). This Mootools-specific implementation worked great in Firefox, but did not result in a confirm popup in Chrome or Safari:

window.addEvent("beforeunload", function() {
    return "Are you sure you want to leave this page?";
});

So in order to get my onbeforeonload event to work across browsers, I had to use the JavaScript native call:

window.onbeforeunload = function() {
    return "Are you sure you want to leave this page?";
}

Not sure why this is the case, or if it's been fixed in later versions of Mootools.

python replace single backslash with double backslash

In python \ (backslash) is used as an escape character. What this means that in places where you wish to insert a special character (such as newline), you would use the backslash and another character (\n for newline)

With your example string you would notice that when you put "C:\Users\Josh\Desktop\20130216" in the repl you will get "C:\\Users\\Josh\\Desktop\x8130216". This is because \2 has a special meaning in a python string. If you wish to specify \ then you need to put two \\ in your string.

"C:\\Users\\Josh\\Desktop\\28130216"

The other option is to notify python that your entire string must NOT use \ as an escape character by pre-pending the string with r

r"C:\Users\Josh\Desktop\20130216"

This is a "raw" string, and very useful in situations where you need to use lots of backslashes such as with regular expression strings.

In case you still wish to replace that single \ with \\ you would then use:

directory = string.replace(r"C:\Users\Josh\Desktop\20130216", "\\", "\\\\")

Notice that I am not using r' in the last two strings above. This is because, when you use the r' form of strings you cannot end that string with a single \

Why can't Python's raw string literals end with a single backslash?

https://pythonconquerstheuniverse.wordpress.com/2008/06/04/gotcha-%E2%80%94-backslashes-are-escape-characters/

SQL Server Case Statement when IS NULL

Take a look at the ISNULL function. It helps you replace NULL values for other values. http://msdn.microsoft.com/en-us/library/ms184325.aspx

Jenkins Host key verification failed

Try

ssh-keygen -R hostname

-R hostname Removes all keys belonging to hostname from a known_hosts file. This option is useful to delete hashed hosts

Creating and Update Laravel Eloquent

like @JuanchoRamone posted above (thank @Juancho) it's very useful for me, but if your data is array you should modify a little like this:

public static function createOrUpdate($data, $keys) {
    $record = self::where($keys)->first();
    if (is_null($record)) {
        return self::create($data);
    } else {
        return $record->update($data);
    }
}

ERROR 1115 (42000): Unknown character set: 'utf8mb4'

Open your mysql file any edit tool

find

/*!40101 SET NAMES utf8mb4 */;

change

/*!40101 SET NAMES utf8 */;

Save and upload ur mysql.

How to abort a Task like aborting a Thread (Thread.Abort method)?

Everyone knows (hopefully) its bad to terminate thread. The problem is when you don't own a piece of code you're calling. If this code is running in some do/while infinite loop , itself calling some native functions, etc. you're basically stuck. When this happens in your own code termination, stop or Dispose call, it's kinda ok to start shooting the bad guys (so you don't become a bad guy yourself).

So, for what it's worth, I've written those two blocking functions that use their own native thread, not a thread from the pool or some thread created by the CLR. They will stop the thread if a timeout occurs:

// returns true if the call went to completion successfully, false otherwise
public static bool RunWithAbort(this Action action, int milliseconds) => RunWithAbort(action, new TimeSpan(0, 0, 0, 0, milliseconds));
public static bool RunWithAbort(this Action action, TimeSpan delay)
{
    if (action == null)
        throw new ArgumentNullException(nameof(action));

    var source = new CancellationTokenSource(delay);
    var success = false;
    var handle = IntPtr.Zero;
    var fn = new Action(() =>
    {
        using (source.Token.Register(() => TerminateThread(handle, 0)))
        {
            action();
            success = true;
        }
    });

    handle = CreateThread(IntPtr.Zero, IntPtr.Zero, fn, IntPtr.Zero, 0, out var id);
    WaitForSingleObject(handle, 100 + (int)delay.TotalMilliseconds);
    CloseHandle(handle);
    return success;
}

// returns what's the function should return if the call went to completion successfully, default(T) otherwise
public static T RunWithAbort<T>(this Func<T> func, int milliseconds) => RunWithAbort(func, new TimeSpan(0, 0, 0, 0, milliseconds));
public static T RunWithAbort<T>(this Func<T> func, TimeSpan delay)
{
    if (func == null)
        throw new ArgumentNullException(nameof(func));

    var source = new CancellationTokenSource(delay);
    var item = default(T);
    var handle = IntPtr.Zero;
    var fn = new Action(() =>
    {
        using (source.Token.Register(() => TerminateThread(handle, 0)))
        {
            item = func();
        }
    });

    handle = CreateThread(IntPtr.Zero, IntPtr.Zero, fn, IntPtr.Zero, 0, out var id);
    WaitForSingleObject(handle, 100 + (int)delay.TotalMilliseconds);
    CloseHandle(handle);
    return item;
}

[DllImport("kernel32")]
private static extern bool TerminateThread(IntPtr hThread, int dwExitCode);

[DllImport("kernel32")]
private static extern IntPtr CreateThread(IntPtr lpThreadAttributes, IntPtr dwStackSize, Delegate lpStartAddress, IntPtr lpParameter, int dwCreationFlags, out int lpThreadId);

[DllImport("kernel32")]
private static extern bool CloseHandle(IntPtr hObject);

[DllImport("kernel32")]
private static extern int WaitForSingleObject(IntPtr hHandle, int dwMilliseconds);

getting exception "IllegalStateException: Can not perform this action after onSaveInstanceState"

I was always getting this when I tried to show fragment in onActivityForResult() method, so the problem was next:

  1. My Activity is paused and stopped, which means, that onSaveInstanceState() was called already (for both pre-Honeycomb and post-Honeycomb devices).
  2. In case of any result I made transaction to show/hide fragment, which causes this IllegalStateException.

What I made is next:

  1. Added value for determining if action I want was done (e.g. taking photo from camere - isPhotoTaken) - it can be boolean or integer value depending how much different transactions you need.
  2. In overriden onResumeFragments() method I checked for my value and after made fragment transactions I needed. In this case commit() was not done after onSaveInstanceState, as state was returned in onResumeFragments() method.

Python unicode equal comparison failed

You may use the == operator to compare unicode objects for equality.

>>> s1 = u'Hello'
>>> s2 = unicode("Hello")
>>> type(s1), type(s2)
(<type 'unicode'>, <type 'unicode'>)
>>> s1==s2
True
>>> 
>>> s3='Hello'.decode('utf-8')
>>> type(s3)
<type 'unicode'>
>>> s1==s3
True
>>> 

But, your error message indicates that you aren't comparing unicode objects. You are probably comparing a unicode object to a str object, like so:

>>> u'Hello' == 'Hello'
True
>>> u'Hello' == '\x81\x01'
__main__:1: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
False

See how I have attempted to compare a unicode object against a string which does not represent a valid UTF8 encoding.

Your program, I suppose, is comparing unicode objects with str objects, and the contents of a str object is not a valid UTF8 encoding. This seems likely the result of you (the programmer) not knowing which variable holds unicide, which variable holds UTF8 and which variable holds the bytes read in from a file.

I recommend http://nedbatchelder.com/text/unipain.html, especially the advice to create a "Unicode Sandwich."

Does Internet Explorer 8 support HTML 5?

IE8 beta 2 supports two APIs from HTML5: cross-document messaging and non-SQL storage.

IE8 beta 2 doesn’t implement the HTML5 parsing algorithm or the new elements (no <canvas> or <video> support).

There are also bug fixes that align IE8 better with HTML5.

Change the "No file chosen":

Just change the width of the input. Around 90px

<input type="file" style="width: 90px" />

Eclipse JUnit - possible causes of seeing "initializationError" in Eclipse window

I had the same problem, the solution for me is the following.

I had only install the junit.jar file from the web, but this library related with the hacrest-core.jar When I downloaded the hacrest-core.jar file and added it in my project everything works fine.

How to code a BAT file to always run as admin mode?

Use the complete physical drive\path to your Target batch file in the shortcut Properties.

This does not work in Windows 10 if you use subst drives like I tried to do at first...

HTTP Error 404.3-Not Found in IIS 7.5

In my case, along with Mekanik's suggestions, I was receiving this error in Windows Server 2012 and I had to tick "HTTP Activation" in "Add Role Services".

How do I specify unique constraint for multiple columns in MySQL?

This works for mysql version 5.5.32

ALTER TABLE  `tablename` ADD UNIQUE (`column1` ,`column2`);

Android Closing Activity Programmatically

you can use this.finish() if you want to close current activity.

this.finish()

Scraping data from website using vba

This question asked long before. But I thought following information will useful for newbies. Actually you can easily get the values from class name like this.

Sub ExtractLastValue()

Set objIE = CreateObject("InternetExplorer.Application")

objIE.Top = 0
objIE.Left = 0
objIE.Width = 800
objIE.Height = 600

objIE.Visible = True

objIE.Navigate ("https://uk.investing.com/rates-bonds/financial-futures/")

Do
DoEvents
Loop Until objIE.readystate = 4

MsgBox objIE.document.getElementsByClassName("pid-8907-last")(0).innerText

End Sub

And if you are new to web scraping please read this blog post.

Web Scraping - Basics

And also there are various techniques to extract data from web pages. This article explain few of them with examples.

Web Scraping - Collecting Data From a Webpage

The Response content must be a string or object implementing __toString(), "boolean" given after move to psql

You can use json_decode(Your variable Name):

json_decode($result)

I was getting value from Model.where a column has value like this way

{"dayList":[
            {"day":[1,2,3,4],"time":[{"in_time":"10:00"},{"late_time":"15:00"},{"out_time":"16:15"}]
             },
             {"day":[5,6,7],"time":[{"in_time":"10:00"},{"late_time":"15:00"},{"out_time":"16:15"}]}
           ]
}

so access this value form model. you have to use this code.

$dayTimeListObject = json_decode($settingAttendance->bio_attendance_day_time,1);

 foreach ( $dayTimeListObject['dayList'] as $dayListArr)
 {
     foreach ( $dayListArr['day'] as $dayIndex)
     {
         if( $dayIndex == Date('w',strtotime('2020-02-11')))
         {
             $dayTimeList= $dayListArr['time'];
         }
     }
 }

 return $dayTimeList[2]['out_time'] ;

You can also define caste in your Model file.

 protected $casts = [
    'your-column-name' => 'json'
  ];

so after this no need of this line .

$dayTimeListObject = json_decode($settingAttendance->bio_attendance_day_time,1);

you can directly access this code.

$settingAttendance->bio_attendance_day_time

Android: how to convert whole ImageView to Bitmap?

Just thinking out loud here (with admittedly little expertise working with graphics in Java) maybe something like this would work?:

ImageView iv = (ImageView)findViewById(R.id.imageview);
Bitmap bitmap = Bitmap.createBitmap(iv.getWidth(), iv.getHeight(), Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(bitmap);
iv.draw(canvas);

Out of curiosity, what are you trying to accomplish? There may be a better way to achieve your goal than what you have in mind.

Oracle SQL : timestamps in where clause

For everyone coming to this thread with fractional seconds in your timestamp use:

to_timestamp('2018-11-03 12:35:20.419000', 'YYYY-MM-DD HH24:MI:SS.FF')

How to develop a soft keyboard for Android?

A good place to start is the sample application provided on the developer docs.

  • Guidelines would be to just make it as usable as possible. Take a look at the others available on the market to see what you should be aiming for
  • Yes, services can do most things, including internet; provided you have asked for those permissions
  • You can open activities and do anything you like n those if you run into a problem with doing some things in the keyboard. For example HTC's keyboard has a button to open the settings activity, and another to open a dialog to change languages.

Take a look at other IME's to see what you should be aiming for. Some (like the official one) are open source.

How to get the current loop index when using Iterator?

This would be the simplest solution!

std::vector<double> v (5);

for(auto itr = v.begin();itr != v.end();++itr){

 auto current_loop_index = itr - v.begin();

  std::cout << current_loop_index << std::endl;

}

Tested on gcc-9 with -std=c++11 flag

Output:

0
1
2
3
4

Boxplot show the value of mean

You can use the output value from stat_summary()

ggplot(data=PlantGrowth, aes(x=group, y=weight, fill=group)) 
+ geom_boxplot() 
+ stat_summary(fun.y=mean, colour="darkred", geom="point", hape=18, size=3,show_guide = FALSE)
+ stat_summary(fun.y=mean, colour="red", geom="text", show_guide = FALSE, 
               vjust=-0.7, aes( label=round(..y.., digits=1)))

Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object

There could be several things causing this and it somewhat depends on what you have set up in your database.

First, you could be using a PK in the table that is also an FK to another table making the relationship 1-1. IN this case you may need to do an update rather than an insert. If you really can have only one address record for an order this may be what is happening.

Next you could be using some sort of manual process to determine the id ahead of time. The trouble with those manual processes is that they can create race conditions where two records gab the same last id and increment it by one and then the second one can;t insert.

Third, you query as it is sent to the database may be creating two records. To determine if this is the case, Run Profiler to see exactly what SQL code you are sending and if ti is a select instead of a values clause, then run the select and see if you have due to the joins gotten some records to be duplicated. IN any even when you are creating code on the fly like this the first troubleshooting step is ALWAYS to run Profiler and see if what got sent was what you expected to be sent.

how to execute php code within javascript

Any server side stuff such as php declaration must get evaluated in the host file (file with a .php extension) inside the script tags such as below

<script type="text/javascript">
    var1 = "<?php echo 'Hello';?>";
</script>

Then in the .js file, you can use the variable

alert(var1);

If you try to evaluate php declaration in the .js file, it will NOT work

How can you profile a Python script?

Simplest and quickest way to find where all the time is going.

1. pip install snakeviz

2. python -m cProfile -o temp.dat <PROGRAM>.py

3. snakeviz temp.dat

Draws a pie chart in a browser. Biggest piece is the problem function. Very simple.

Password encryption/decryption code in .NET

 string clearText = txtPassword.Text;
        string EncryptionKey = "MAKV2SPBNI99212";
        byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
        using (Aes encryptor = Aes.Create())
        {
            Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
            encryptor.Key = pdb.GetBytes(32);
            encryptor.IV = pdb.GetBytes(16);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(clearBytes, 0, clearBytes.Length);
                    cs.Close();
                }
                clearText = Convert.ToBase64String(ms.ToArray());
            }
        }

Add new column with foreign key constraint in one command

In MS SQL SERVER:

With user defined foreign key name

ALTER TABLE tableName
ADD columnName dataType,
CONSTRAINT fkName FOREIGN KEY(fkColumnName) 
   REFERENCES pkTableName(pkTableColumnName);

Without user defined foreign key name

ALTER TABLE tableName
ADD columnName dataType,
FOREIGN KEY(fkColumnName) REFERENCES pkTableName(pkTableColumnName);

Java - Best way to print 2D array?

Adapting from https://stackoverflow.com/a/49428678/1527469 (to add indexes):

System.out.print(" ");
for (int row = 0; row < array[0].length; row++) {
    System.out.print("\t" + row );
}
System.out.println();
for (int row = 0; row < array.length; row++) {
    for (int col = 0; col < array[row].length; col++) {
        if (col < 1) {
            System.out.print(row);
            System.out.print("\t" + array[row][col]);
        } else {

            System.out.print("\t" + array[row][col]);
        }
    }
    System.out.println();
}

What is the minimum I have to do to create an RPM file?

If you are familiar with Maven there also rpm-maven-plugin which simplifies making RPMs: you have to write only pom.xml which will be then used to build RPM. RPM build environment is created implicitly by the plugin.

Python CSV error: line contains NULL byte

Instead of csv reader I use read file and split function for string:

lines = open(input_file,'rb') 

for line_all in lines:

    line=line_all.replace('\x00', '').split(";")

How to set default values in Rails?

In case you're dealing with a Model, you can use the Attriutes API in Rails 5+ http://api.rubyonrails.org/classes/ActiveRecord/Attributes/ClassMethods.html#method-i-attribute

just add a migration with a proper column name and then in the model set it with:

class StoreListing < ActiveRecord::Base
  attribute :country, :string, default: 'PT'
end

T-SQL stored procedure that accepts multiple Id values

A superfast XML Method, if you want to use a stored procedure and pass the comma separated list of Department IDs :

Declare @XMLList xml
SET @XMLList=cast('<i>'+replace(@DepartmentIDs,',','</i><i>')+'</i>' as xml)
SELECT x.i.value('.','varchar(5)') from @XMLList.nodes('i') x(i))

All credit goes to Guru Brad Schulz's Blog

SQL injection that gets around mysql_real_escape_string()

The short answer is yes, yes there is a way to get around mysql_real_escape_string(). #For Very OBSCURE EDGE CASES!!!

The long answer isn't so easy. It's based off an attack demonstrated here.

The Attack

So, let's start off by showing the attack...

mysql_query('SET NAMES gbk');
$var = mysql_real_escape_string("\xbf\x27 OR 1=1 /*");
mysql_query("SELECT * FROM test WHERE name = '$var' LIMIT 1");

In certain circumstances, that will return more than 1 row. Let's dissect what's going on here:

  1. Selecting a Character Set

    mysql_query('SET NAMES gbk');
    

    For this attack to work, we need the encoding that the server's expecting on the connection both to encode ' as in ASCII i.e. 0x27 and to have some character whose final byte is an ASCII \ i.e. 0x5c. As it turns out, there are 5 such encodings supported in MySQL 5.6 by default: big5, cp932, gb2312, gbk and sjis. We'll select gbk here.

    Now, it's very important to note the use of SET NAMES here. This sets the character set ON THE SERVER. If we used the call to the C API function mysql_set_charset(), we'd be fine (on MySQL releases since 2006). But more on why in a minute...

  2. The Payload

    The payload we're going to use for this injection starts with the byte sequence 0xbf27. In gbk, that's an invalid multibyte character; in latin1, it's the string ¿'. Note that in latin1 and gbk, 0x27 on its own is a literal ' character.

    We have chosen this payload because, if we called addslashes() on it, we'd insert an ASCII \ i.e. 0x5c, before the ' character. So we'd wind up with 0xbf5c27, which in gbk is a two character sequence: 0xbf5c followed by 0x27. Or in other words, a valid character followed by an unescaped '. But we're not using addslashes(). So on to the next step...

  3. mysql_real_escape_string()

    The C API call to mysql_real_escape_string() differs from addslashes() in that it knows the connection character set. So it can perform the escaping properly for the character set that the server is expecting. However, up to this point, the client thinks that we're still using latin1 for the connection, because we never told it otherwise. We did tell the server we're using gbk, but the client still thinks it's latin1.

    Therefore the call to mysql_real_escape_string() inserts the backslash, and we have a free hanging ' character in our "escaped" content! In fact, if we were to look at $var in the gbk character set, we'd see:

    ?' OR 1=1 /*

    Which is exactly what the attack requires.

  4. The Query

    This part is just a formality, but here's the rendered query:

    SELECT * FROM test WHERE name = '?' OR 1=1 /*' LIMIT 1
    

Congratulations, you just successfully attacked a program using mysql_real_escape_string()...

The Bad

It gets worse. PDO defaults to emulating prepared statements with MySQL. That means that on the client side, it basically does a sprintf through mysql_real_escape_string() (in the C library), which means the following will result in a successful injection:

$pdo->query('SET NAMES gbk');
$stmt = $pdo->prepare('SELECT * FROM test WHERE name = ? LIMIT 1');
$stmt->execute(array("\xbf\x27 OR 1=1 /*"));

Now, it's worth noting that you can prevent this by disabling emulated prepared statements:

$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

This will usually result in a true prepared statement (i.e. the data being sent over in a separate packet from the query). However, be aware that PDO will silently fallback to emulating statements that MySQL can't prepare natively: those that it can are listed in the manual, but beware to select the appropriate server version).

The Ugly

I said at the very beginning that we could have prevented all of this if we had used mysql_set_charset('gbk') instead of SET NAMES gbk. And that's true provided you are using a MySQL release since 2006.

If you're using an earlier MySQL release, then a bug in mysql_real_escape_string() meant that invalid multibyte characters such as those in our payload were treated as single bytes for escaping purposes even if the client had been correctly informed of the connection encoding and so this attack would still succeed. The bug was fixed in MySQL 4.1.20, 5.0.22 and 5.1.11.

But the worst part is that PDO didn't expose the C API for mysql_set_charset() until 5.3.6, so in prior versions it cannot prevent this attack for every possible command! It's now exposed as a DSN parameter.

The Saving Grace

As we said at the outset, for this attack to work the database connection must be encoded using a vulnerable character set. utf8mb4 is not vulnerable and yet can support every Unicode character: so you could elect to use that instead—but it has only been available since MySQL 5.5.3. An alternative is utf8, which is also not vulnerable and can support the whole of the Unicode Basic Multilingual Plane.

Alternatively, you can enable the NO_BACKSLASH_ESCAPES SQL mode, which (amongst other things) alters the operation of mysql_real_escape_string(). With this mode enabled, 0x27 will be replaced with 0x2727 rather than 0x5c27 and thus the escaping process cannot create valid characters in any of the vulnerable encodings where they did not exist previously (i.e. 0xbf27 is still 0xbf27 etc.)—so the server will still reject the string as invalid. However, see @eggyal's answer for a different vulnerability that can arise from using this SQL mode.

Safe Examples

The following examples are safe:

mysql_query('SET NAMES utf8');
$var = mysql_real_escape_string("\xbf\x27 OR 1=1 /*");
mysql_query("SELECT * FROM test WHERE name = '$var' LIMIT 1");

Because the server's expecting utf8...

mysql_set_charset('gbk');
$var = mysql_real_escape_string("\xbf\x27 OR 1=1 /*");
mysql_query("SELECT * FROM test WHERE name = '$var' LIMIT 1");

Because we've properly set the character set so the client and the server match.

$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$pdo->query('SET NAMES gbk');
$stmt = $pdo->prepare('SELECT * FROM test WHERE name = ? LIMIT 1');
$stmt->execute(array("\xbf\x27 OR 1=1 /*"));

Because we've turned off emulated prepared statements.

$pdo = new PDO('mysql:host=localhost;dbname=testdb;charset=gbk', $user, $password);
$stmt = $pdo->prepare('SELECT * FROM test WHERE name = ? LIMIT 1');
$stmt->execute(array("\xbf\x27 OR 1=1 /*"));

Because we've set the character set properly.

$mysqli->query('SET NAMES gbk');
$stmt = $mysqli->prepare('SELECT * FROM test WHERE name = ? LIMIT 1');
$param = "\xbf\x27 OR 1=1 /*";
$stmt->bind_param('s', $param);
$stmt->execute();

Because MySQLi does true prepared statements all the time.

Wrapping Up

If you:

  • Use Modern Versions of MySQL (late 5.1, all 5.5, 5.6, etc) AND mysql_set_charset() / $mysqli->set_charset() / PDO's DSN charset parameter (in PHP = 5.3.6)

OR

  • Don't use a vulnerable character set for connection encoding (you only use utf8 / latin1 / ascii / etc)

You're 100% safe.

Otherwise, you're vulnerable even though you're using mysql_real_escape_string()...

git push rejected

If nothing works, try:

git pull --allow-unrelated-histories <repo> <branch>

then do:

git push --set-upstream origin master

notifyDataSetChanged example

I had the same problem and I prefer not to replace the entire ArrayAdapter with a new instance continuously. Thus I have the AdapterHelper do the heavy lifting somewhere else.

Add this where you would normally (try to) call notify

new AdapterHelper().update((ArrayAdapter)adapter, new ArrayList<Object>(yourArrayList));
adapter.notifyDataSetChanged();

AdapterHelper class

public class AdapterHelper {
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public void update(ArrayAdapter arrayAdapter, ArrayList<Object> listOfObject){
        arrayAdapter.clear();
        for (Object object : listOfObject){
            arrayAdapter.add(object);
        }
    }
}

python JSON object must be str, bytes or bytearray, not 'dict

import json
data = json.load(open('/Users/laxmanjeergal/Desktop/json.json'))
jtopy=json.dumps(data) #json.dumps take a dictionary as input and returns a string as output.
dict_json=json.loads(jtopy) # json.loads take a string as input and returns a dictionary as output.
print(dict_json["shipments"])

Android Device not recognized by adb

Go to prompt command and type "adb devices". If it is empty, then make sure you allowed for "MTP Transfer" or similar and you enabled debugging on your phone.

To enable debugging, follow this tutorial: https://www.kingoapp.com/root-tutorials/how-to-enable-usb-debugging-mode-on-android.htm

Then type "adb devices" again. If a device is listed in there, then it should work now.

Differences between key, superkey, minimal superkey, candidate key and primary key

Superkey - An attribute or set of attributes that uniquely defines a tuple within a relation. However, a superkey may contain additional attributes that are not necessary for unique identification.

Candidate key - A superkey such that no proper subset is a superkey within the relation. So, basically has two properties: Each candidate key uniquely identifies tuple in the relation ; & no proper subset of the composite key has the uniqueness property.

Composite key - When a candidate key consists of more than one attribute.

Primary key - The candidate key chosen to identify tuples uniquely within the relation.

Alternate key - Candidate key that is not a primary key.

Foreign key - An attribute or set of attributes within a relation that matches the candidate key of some relation.

Android studio Error "Unsupported Modules Detected: Compilation is not supported for following modules"

I had the exact same error and it was so annoying to see the alert every time I stared Android Studio. I tried the solution mentioned above including invalidating cache, restart etc, nothing made it go away.

In my case, we had a module that was deleted from source and the reference also removed from settings.gradle. Turns out, .idea/modules.xml was still referencing that module.

All I needed to do was remove that line from <modules> in .idea/modules.xml and it made it all go away.

How to show/hide if variable is null

To clarify, the above example does work, my code in the example did not work for unrelated reasons.

If myvar is false, null or has never been used before (i.e. $scope.myvar or $rootScope.myvar never called), the div will not show. Once any value has been assigned to it, the div will show, except if the value is specifically false.

The following will cause the div to show:

$scope.myvar = "Hello World";

or

$scope.myvar = true;

The following will hide the div:

$scope.myvar = null;

or

$scope.myvar = false;

Apply Calibri (Body) font to text

If there is space between the letters of the font, you need to use quote.

font-family:"Calibri (Body)";

Factory Pattern. When to use factory methods?

They're also useful when you need several "constructors" with the same parameter type but with different behavior.

How to pass boolean values to a PowerShell script from a command prompt

I think, best way to use/set boolean value as parameter is to use in your PS script it like this:

Param(
    [Parameter(Mandatory=$false)][ValidateSet("true", "false")][string]$deployApp="false"   
)

$deployAppBool = $false
switch($deployPmCmParse.ToLower()) {
    "true" { $deployAppBool = $true }
    default { $deployAppBool = $false }
}

So now you can use it like this:

.\myApp.ps1 -deployAppBool True
.\myApp.ps1 -deployAppBool TRUE
.\myApp.ps1 -deployAppBool true
.\myApp.ps1 -deployAppBool "true"
.\myApp.ps1 -deployAppBool false
#and etc...

So in arguments from cmd you can pass boolean value as simple string :).

INNER JOIN in UPDATE sql for DB2

Joins in update statements are non-standard and not supported by all vendors. What you're trying to do can be accomplished with a sub-select:

update
  file1
set
  firstfield = (select 'stuff' concat something from file2 where substr(file1.field1, 10, 20) = substr(file2.xxx,1,10) )
where
  file1.foo like 'BLAH%'

adding css class to multiple elements

You need to qualify the a part of the selector too:

.button input, .button a {
    //css stuff here
}

Basically, when you use the comma to create a group of selectors, each individual selector is completely independent. There is no relationship between them.

Your original selector therefore matched "all elements of type 'input' that are descendants of an element with the class name 'button', and all elements of type 'a'".

How do I get unique elements in this array?

For those hitting this up in the future, you can now use the Mongoid::Criteria#distinct method from Origin to select only distinct values from the database:

# Requires a Mongoid::Criteria
Attendees.all.distinct(:user_id)

http://mongoid.org/en/mongoid/docs/querying.html (v3.1.0)

Label on the left side instead above an input field

The Bootstrap 3 documentation talks about this in the CSS documentation tab in the section labelled "Requires custom widths", which states:

Inputs, selects, and textareas are 100% wide by default in Bootstrap. To use the inline form, you'll have to set a width on the form controls used within.

If you use your browser and Firebug or Chrome tools to suppress or reduce the "width" style, you should see things line up they way you want. Clearly you can then create the appropriate CSS to fix the issue.

However, I find it odd that I need to do this at all. I couldn't help but feel this manipulation was both annoying and in the long term, error prone. Ultimately, I used a dummy class and some JS to globally shim all my inline inputs. It was small number of cases, so not much of a concern.

Nonetheless, I too would love to hear from someone who has the "right" solution, and could eliminate my shim/hack.

Hope this helps, and props to you for not blowing a gasket at all the people that ignored your request as a Bootstrap 3 concern.

Android Paint: .measureText() vs .getTextBounds()

This is how I calculated the real dimensions for the first letter (you can change the method header to suit your needs, i.e. instead of char[] use String):

private void calculateTextSize(char[] text, PointF outSize) {
    // use measureText to calculate width
    float width = mPaint.measureText(text, 0, 1);

    // use height from getTextBounds()
    Rect textBounds = new Rect();
    mPaint.getTextBounds(text, 0, 1, textBounds);
    float height = textBounds.height();
    outSize.x = width;
    outSize.y = height;
}

Note that I'm using TextPaint instead of the original Paint class.

Getting a list item by index

.NET List data structure is an Array in a "mutable shell".

So you can use indexes for accessing to it's elements like:

var firstElement = myList[0];
var secondElement = myList[1];

Starting with C# 8.0 you can use Index and Range classes for accessing elements. They provides accessing from the end of sequence or just access a specific part of sequence:

var lastElement = myList[^1]; // Using Index
var fiveElements = myList[2..7]; // Using Range, note that 7 is exclusive

You can combine indexes and ranges together:

var elementsFromThirdToEnd = myList[2..^0]; // Index and Range together

Also you can use LINQ ElementAt method but for 99% of cases this is really not necessary and just slow performance solution.

Multiple Where clauses in Lambda expressions

Maybe

x=> x.Lists.Include(l => l.Title)
    .Where(l => l.Title != string.Empty)
    .Where(l => l.InternalName != string.Empty)

?

You can probably also put it in the same where clause:

x=> x.Lists.Include(l => l.Title)
    .Where(l => l.Title != string.Empty && l.InternalName != string.Empty)

How to show x and y axes in a MATLAB graph?

Easiest solution:

plot([0,0],[0.0], xData, yData);

This creates an invisible line between the points [0,0] to [0,0] and since Matlab wants to include these points it will shows the axis.

Get the first element of each tuple in a list in Python

If you don't want to use list comprehension by some reasons, you can use map and operator.itemgetter:

>>> from operator import itemgetter
>>> rows = [(1, 2), (3, 4), (5, 6)]
>>> map(itemgetter(1), rows)
[2, 4, 6]
>>>

Wamp Server not goes to green color

I've had the above solutions work for me on many occasions, except one; that was after I buggered up an alias file - ie a file that allows the website folder to be located in another location other than the www folder. Here's the solution:

  1. Go to c:/wamp/alias
  2. Cut all of the alias files and paste in a temp folder somewhere
  3. Restart all WAMP services
  4. If the WAMP icon goes green, then add each alias file back to the alias folder one by one, restart WAMP, and when WAMP doesn't start, you know that alias file has some bad data in it. So, fix that file or delete it. Your choice.

Nginx 403 forbidden for all files

I've got this error and I finally solved it with the command below.

restorecon -r /var/www/html

The issue is caused when you mv something from one place to another. It preserves the selinux context of the original when you move it, so if you untar something in /home or /tmp it gets given an selinux context that matches its location. Now you mv that to /var/www/html and it takes the context saying it belongs in /tmp or /home with it and httpd is not allowed by policy to access those files.

If you cp the files instead of mv them, the selinux context gets assigned according to the location you're copying to, not where it's coming from. Running restorecon puts the context back to its default and fixes it too.

PHP strtotime +1 month adding an extra month

This should be

$endOfCycle=date('Y-m-d', strtotime("+30 days"));

strtotime

expects to be given a string containing a US English date format and will try to parse that format into a Unix timestamp (the number of seconds since January 1 1970 00:00:00 UTC), relative to the timestamp given in now, or the current time if now is not supplied.

while

date

Returns a string formatted according to the given format string using the given integer timestamp or the current time if no timestamp is given.

See the manual pages for:

How do I split a string into an array of characters?

You can use the regular expression /(?!$)/:

"overpopulation".split(/(?!$)/)

The negative look-ahead assertion (?!$) will match right in front of every character.

Parse HTML table to Python list?

Sven Marnach excellent solution is directly translatable into ElementTree which is part of recent Python distributions:

from xml.etree import ElementTree as ET

s = """<table>
  <tr><th>Event</th><th>Start Date</th><th>End Date</th></tr>
  <tr><td>a</td><td>b</td><td>c</td></tr>
  <tr><td>d</td><td>e</td><td>f</td></tr>
  <tr><td>g</td><td>h</td><td>i</td></tr>
</table>
"""

table = ET.XML(s)
rows = iter(table)
headers = [col.text for col in next(rows)]
for row in rows:
    values = [col.text for col in row]
    print(dict(zip(headers, values)))

same output as Sven Marnach's answer...

Bootstrap 3 jquery event for active tab change

This worked for me.

$('.nav-pills > li > a').click( function() {
    $('.nav-pills > li.active').removeClass('active');
    $(this).parent().addClass('active');
} );

Where Is Machine.Config?

It semi-depends though... mine is:

C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG

and

C:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG

How can I process each letter of text using Javascript?

If you want to do a transformation on the text on a character level, and get the transformed text back at the end, you would do something like this:

var value = "alma";
var new_value = value.split("").map(function(x) { return x+"E" }).join("")

So the steps:

  • Split the string into an array (list) of characters
  • Map each character via a functor
  • Join the resulting array of chars together into the resulting string

How to generate and auto increment Id with Entity Framework

This is a guess :)

Is it because the ID is a string? What happens if you change it to int?

I mean:

 public int Id { get; set; }

How to create an 2D ArrayList in java?

This can be achieve by creating object of List data structure, as follows

List list = new ArrayList();

For more information refer this link

How to create a Multidimensional ArrayList in Java?

R: Comment out block of code

Most of the editors take some kind of shortcut to comment out blocks of code. The default editors use something like command or control and single quote to comment out selected lines of code. In RStudio it's Command or Control+/. Check in your editor.

It's still commenting line by line, but they also uncomment selected lines as well. For the Mac RGUI it's command-option ' (I'm imagining windows is control option). For Rstudio it's just Command or Control + Shift + C again.

These shortcuts will likely change over time as editors get updated and different software becomes the most popular R editors. You'll have to look it up for whatever software you have.

Any implementation of Ordered Set in Java?

Take a look at LinkedHashSet class

From Java doc:

Hash table and linked list implementation of the Set interface, with predictable iteration order. This implementation differs from HashSet in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is the order in which elements were inserted into the set (insertion-order). Note that insertion order is not affected if an element is re-inserted into the set. (An element e is reinserted into a set s if s.add(e) is invoked when s.contains(e) would return true immediately prior to the invocation.).

Java JTable setting Column Width

Use this method

public static void setColumnWidths(JTable table, int... widths) {
    TableColumnModel columnModel = table.getColumnModel();
    for (int i = 0; i < widths.length; i++) {
        if (i < columnModel.getColumnCount()) {
            columnModel.getColumn(i).setMaxWidth(widths[i]);
        }
        else break;
    }
}

Or extend the JTable class:

public class Table extends JTable {
    public void setColumnWidths(int... widths) {
        for (int i = 0; i < widths.length; i++) {
            if (i < columnModel.getColumnCount()) {
                columnModel.getColumn(i).setMaxWidth(widths[i]);
            }
            else break;
        }
    }
}

And then

table.setColumnWidths(30, 150, 100, 100);

No output to console from a WPF application?

Right click on the project, "Properties", "Application" tab, change "Output Type" to "Console Application", and then it will also have a console.

Anonymous method in Invoke call

You need to create a delegate type. The keyword 'delegate' in the anonymous method creation is a bit misleading. You are not creating an anonymous delegate but an anonymous method. The method you created can be used in a delegate. Like this:

myControl.Invoke(new MethodInvoker(delegate() { (MyMethod(this, new MyEventArgs(someParameter)); }));

How to set conditional breakpoints in Visual Studio?

Just another way of doing it, (or if you are using express) add the condition in code:

if(yourCondition)
{
    System.Diagnostics.Debugger.Break();
}

Reload .profile in bash shell script (in unix)?

Try this to reload your current shell:

source ~/.profile

node.js: cannot find module 'request'

I had same problem, for me npm install request --save solved the problem. Hope it helps.

"End of script output before headers" error in Apache

Probably this is an SELinux block. Try this:

# setsebool -P httpd_enable_cgi 1
# chcon -R -t httpd_sys_script_exec_t cgi-bin/your_script.cgi

How do you count the elements of an array in java

You can declare an array of booleans with the same length of your array:

true: is used
false: is not used

and change the value of the same cell number to true. Then you can count how many cells are used by using a for loop.

Git pull till a particular commit

git pull is nothing but git fetch followed by git merge. So what you can do is

git fetch remote example_branch

git merge <commit_hash>

Run a mySQL query as a cron job?

Try creating a shell script like the one below:

#!/bin/bash

mysql --user=[username] --password=[password] --database=[db name] --execute="DELETE FROM tbl_message WHERE DATEDIFF( NOW( ) ,  timestamp ) >=7"

You can then add this to the cron

How do you iterate through every file/directory recursively in standard C++?

In standard C++, technically there is no way to do this since standard C++ has no conception of directories. If you want to expand your net a little bit, you might like to look at using Boost.FileSystem. This has been accepted for inclusion in TR2, so this gives you the best chance of keeping your implementation as close as possible to the standard.

An example, taken straight from the website:

bool find_file( const path & dir_path,         // in this directory,
                const std::string & file_name, // search for this name,
                path & path_found )            // placing path here if found
{
  if ( !exists( dir_path ) ) return false;
  directory_iterator end_itr; // default construction yields past-the-end
  for ( directory_iterator itr( dir_path );
        itr != end_itr;
        ++itr )
  {
    if ( is_directory(itr->status()) )
    {
      if ( find_file( itr->path(), file_name, path_found ) ) return true;
    }
    else if ( itr->leaf() == file_name ) // see below
    {
      path_found = itr->path();
      return true;
    }
  }
  return false;
}

How do I update a Linq to SQL dbml file?

You could also check out the PLINQO set of code generation templates, based on CodeSmith, which allow you to do a lot of neat things for and with Linq-to-SQL:

  • generate one file per class (instead of a single, huge file)
  • update your model as needed
  • many more features

Check out the PLINQO site at http://www.plinqo.com and have a look at the intro videos.

The second tool I know of are the Huagati DBML/EDMX tools, which allow update of DBML (Linq-to-SQL) and EDMX (Entity Framework) mapping files, and more (like naming conventions etc.).

Marc

Unioning two tables with different number of columns

I came here and followed above answer. But mismatch in the Order of data type caused an error. The below description from another answer will come handy.

Are the results above the same as the sequence of columns in your table? because oracle is strict in column orders. this example below produces an error:

create table test1_1790 (
col_a varchar2(30),
col_b number,
col_c date);

create table test2_1790 (
col_a varchar2(30),
col_c date,
col_b number);

select * from test1_1790
union all
select * from test2_1790;

ORA-01790: expression must have same datatype as corresponding expression

As you see the root cause of the error is in the mismatching column ordering that is implied by the use of * as column list specifier. This type of errors can be easily avoided by entering the column list explicitly:

select col_a, col_b, col_c from test1_1790 union all select col_a, col_b, col_c from test2_1790; A more frequent scenario for this error is when you inadvertently swap (or shift) two or more columns in the SELECT list:

select col_a, col_b, col_c from test1_1790
union all
select col_a, col_c, col_b from test2_1790;

OR if the above does not solve your problem, how about creating an ALIAS in the columns like this: (the query is not the same as yours but the point here is how to add alias in the column.)

SELECT id_table_a, 
       desc_table_a, 
       table_b.id_user as iUserID, 
       table_c.field as iField
UNION
SELECT id_table_a, 
       desc_table_a, 
       table_c.id_user as iUserID, 
       table_c.field as iField

Selenium Web Driver & Java. Element is not clickable at point (x, y). Other element would receive the click

In case you need to use it with Javascript

We can use arguments[0].click() to simulate click operation.

var element = element(by.linkText('webdriverjs'));
browser.executeScript("arguments[0].click()",element);

How to force two figures to stay on the same page in LaTeX?

You can put two figures inside one figure environment. For example:

\begin{figure}[p]
\centering
\includegraphics{fig1}
\caption{Caption 1}
\includegraphics{fig2}
\caption{Caption 2}
\end{figure}

Each caption will generate a separate figure number.

Chaining Observables in RxJS

About promise composition vs. Rxjs, as this is a frequently asked question, you can refer to a number of previously asked questions on SO, among which :

Basically, flatMap is the equivalent of Promise.then.

For your second question, do you want to replay values already emitted, or do you want to process new values as they arrive? In the first case, check the publishReplay operator. In the second case, standard subscription is enough. However you might need to be aware of the cold. vs. hot dichotomy depending on your source (cf. Hot and Cold observables : are there 'hot' and 'cold' operators? for an illustrated explanation of the concept)

Is there a way to pass jvm args via command line to maven?

I think MAVEN_OPTS would be most appropriate for you. See here: http://maven.apache.org/configure.html

In Unix:

Add the MAVEN_OPTS environment variable to specify JVM properties, e.g. export MAVEN_OPTS="-Xms256m -Xmx512m". This environment variable can be used to supply extra options to Maven.

In Win, you need to set environment variable via the dialogue box

Add ... environment variable by opening up the system properties (WinKey + Pause),... In the same dialog, add the MAVEN_OPTS environment variable in the user variables to specify JVM properties, e.g. the value -Xms256m -Xmx512m. This environment variable can be used to supply extra options to Maven.

Convert a JSON String to a HashMap

You can use Jackson API as well for this :

    final String json = "....your json...";
    final ObjectMapper mapper = new ObjectMapper();
    final MapType type = mapper.getTypeFactory().constructMapType(
        Map.class, String.class, Object.class);
    final Map<String, Object> data = mapper.readValue(json, type);

Sorting a list using Lambda/Linq to objects

This is how I solved my problem:

List<User> list = GetAllUsers();  //Private Method

if (!sortAscending)
{
    list = list
           .OrderBy(r => r.GetType().GetProperty(sortBy).GetValue(r,null))
           .ToList();
}
else
{
    list = list
           .OrderByDescending(r => r.GetType().GetProperty(sortBy).GetValue(r,null))
           .ToList();
}

How do I change the UUID of a virtual disk?

Same solution as @Al3x for Windows x64, in cmd.exe:

cd %programfiles%\Oracle\VirtualBox

VBoxManage internalcommands sethduuid "full/path/to/.vdi"

This randomizes the UUID of the disk. Pro tip: Right click the .vdi file while holding shift and select "Copy as path" to obtain "full/path/to/.vdi" and enable quick edit in cmd.exe, then right click to paste.

Starting a shell in the Docker Alpine container

In case the container is already running:

docker exec -it container_id_or_name ash

Get the current URL with JavaScript?

Adding result for quick reference

window.location;

 Location {href: "https://stackoverflow.com/questions/1034621/get-the-current-url-with-javascript",
 ancestorOrigins: DOMStringList,
 origin: "https://stackoverflow.com",
 replace: ƒ, assign: ƒ, …}

document.location

  Location {href: "https://stackoverflow.com/questions/1034621/get-the-current-url-with-javascript", 
ancestorOrigins: DOMStringList,
 origin: "https://stackoverflow.com",
 replace: ƒ, assign: ƒ
, …}

window.location.pathname

"/questions/1034621/get-the-current-url-with-javascript"

window.location.href

"https://stackoverflow.com/questions/1034621/get-the-current-url-with-javascript"

location.hostname

"stackoverflow.com"

Java Returning method which returns arraylist?

Assuming you have something like so:

public class MyFirstClass {
   ...
   public ArrayList<Integer> myNumbers()    {
    ArrayList<Integer> numbers = new ArrayList<Integer>();
    numbers.add(5);
    numbers.add(11);
    numbers.add(3);
    return(numbers);
   }
   ...
}

You can call that method like so:

public class MySecondClass {
    ...
    MyFirstClass m1 = new MyFirstClass();
    List<Integer> myList = m1.myNumbers();
    ...
}

Since the method you are trying to call is not static, you will have to create an instance of the class which provides this method. Once you create the instance, you will then have access to the method.

Note, that in the code example above, I used this line: List<Integer> myList = m1.myNumbers();. This can be changed by the following: ArrayList<Integer> myList = m1.myNumbers();. However, it is usually recommended to program to an interface, and not to a concrete implementation, so my suggestion for the method you are using would be to do something like so:

public List<Integer> myNumbers()    {
    List<Integer> numbers = new ArrayList<Integer>();
    numbers.add(5);
    numbers.add(11);
    numbers.add(3);
    return(numbers);
   }

This will allow you to assign the contents of that list to whatever implements the List interface.

How to solve “Microsoft Visual Studio (VS)” error “Unable to connect to the configured development Web server”

SOLUTION

This means that you are missing the right for using it. Create it with Netsh Commands for Hypertext Transfer Protocol > add urlacl.

1) Open "Command Line Interface (CLI)" called "Command shell" with Win+R write "cmd"

2) Open CLI windows like administrator with mouse context menu on opened windows or icon "Run as administrator"

3) Insert command to register url

netsh http add urlacl url=http://{ip_addr}:{port}/ user=everyone

NOTE:

How to delete $_POST variable upon pressing 'Refresh' button on browser with PHP?

I have a single form and display where I "add / delete / edit / insert / move" data records using one form and one submit button. What I do first is to check to see if the $_post is set, if not, set it to nothing. then I run through the rest of the code,

then on the actual $_post's I use switches and if / else's based on the data entered and with error checking for each data part required for which function is being used.

After it does whatever to the data, I run a function to clear all the $_post data for each section. you can hit refresh till your blue in the face it won't do anything but refresh the page and display.

So you just need to think logically and make it idiot proof for your users...

Modify tick label text

Caveat: Unless the ticklabels are already set to a string (as is usually the case in e.g. a boxplot), this will not work with any version of matplotlib newer than 1.1.0. If you're working from the current github master, this won't work. I'm not sure what the problem is yet... It may be an unintended change, or it may not be...

Normally, you'd do something along these lines:

import matplotlib.pyplot as plt

fig, ax = plt.subplots()

# We need to draw the canvas, otherwise the labels won't be positioned and 
# won't have values yet.
fig.canvas.draw()

labels = [item.get_text() for item in ax.get_xticklabels()]
labels[1] = 'Testing'

ax.set_xticklabels(labels)

plt.show()

enter image description here

To understand the reason why you need to jump through so many hoops, you need to understand a bit more about how matplotlib is structured.

Matplotlib deliberately avoids doing "static" positioning of ticks, etc, unless it's explicitly told to. The assumption is that you'll want to interact with the plot, and so the bounds of the plot, ticks, ticklabels, etc will be dynamically changing.

Therefore, you can't just set the text of a given tick label. By default, it's re-set by the axis's Locator and Formatter every time the plot is drawn.

However, if the Locators and Formatters are set to be static (FixedLocator and FixedFormatter, respectively), then the tick labels stay the same.

This is what set_*ticklabels or ax.*axis.set_ticklabels does.

Hopefully that makes it slighly more clear as to why changing an individual tick label is a bit convoluted.

Often, what you actually want to do is just annotate a certain position. In that case, look into annotate, instead.

Show whitespace characters in Visual Studio Code

UPDATE (June 2019)

For those willing to toggle whitespace characters using a keyboard shortcut, you can easily add a keybinding for that.

In the latest versions of Visual Studio Code there is now a user-friendly graphical interface (i.e. no need to type JSON data etc) for viewing and editing all the available keyboard shortcuts. It is still under

File > Preferences > Keyboard Shortcuts (or use Ctrl+K Ctrl+S)

There is also a search field to help quickly find (and filter) the desired keybindings. So now both adding new and editing the existing keybindings is much easier:

enter image description here


Toggling whitespace characters has no default keybinding so feel free to add one. Just press the + sign on the left side of the related line (or press Enter, or double click anywhere on that line) and enter the desired combination in the pop-up window.

And if the keybinding you have chosen is already used for some other action(s) there will be a convenient warning which you can click and observe what action(s) already use your chosen keybinding:

enter image description here

As you can see, everything is very intuitive and convenient.
Good job, Microsoft!


Original (old) answer

For those willing to toggle whitespace characters using a keyboard shortcut, you can add a custom binding to the keybindings.json file (File > Preferences > Keyboard Shortcuts).

Example:

// Place your key bindings in this file to overwrite the defaults
[
    {
        "key": "ctrl+shift+i",
        "command": "editor.action.toggleRenderWhitespace"
    }
]

Here I have assigned a combination of Ctrl+Shift+i to toggle invisible characters, you may of course choose another combination.

Length of the String without using length() method

Just to complete this with the most stupid method I can come up with: Generate all possible strings of length 1, use equals to compare them to the original string; if they are equal, the string length is 1. If no string matches, generate all possible strings of length 2, compare them, for string length 2. Etc. Continue until you find the string length or the universe ends, whatever happens first.

What is thread Safe in java?

As Seth stated thread safe means that a method or class instance can be used by multiple threads at the same time without any problems occuring.

Consider the following method:

private int myInt = 0;
public int AddOne()
{
    int tmp = myInt;
    tmp = tmp + 1;
    myInt = tmp;
    return tmp;
}

Now thread A and thread B both would like to execute AddOne(). but A starts first and reads the value of myInt (0) into tmp. Now for some reason the scheduler decides to halt thread A and defer execution to thread B. Thread B now also reads the value of myInt (still 0) into it's own variable tmp. Thread B finishes the entire method, so in the end myInt = 1. And 1 is returned. Now it's Thread A's turn again. Thread A continues. And adds 1 to tmp (tmp was 0 for thread A). And then saves this value in myInt. myInt is again 1.

So in this case the method AddOne() was called two times, but because the method was not implemented in a thread safe way the value of myInt is not 2, as expected, but 1 because the second thread read the variable myInt before the first thread finished updating it.

Creating thread safe methods is very hard in non trivial cases. And there are quite a few techniques. In Java you can mark a method as synchronized, this means that only one thread can execute that method at a given time. The other threads wait in line. This makes a method thread safe, but if there is a lot of work to be done in a method, then this wastes a lot of time. Another technique is to 'mark only a small part of a method as synchronized' by creating a lock or semaphore, and locking this small part (usually called the critical section). There are even some methods that are implemented as lockless thread safe, which means that they are built in such a way that multiple threads can race through them at the same time without ever causing problems, this can be the case when a method only executes one atomic call. Atomic calls are calls that can't be interrupted and can only be done by one thread at a time.

How to set header and options in axios?

You can pass a config object to axios like:

axios({
  method: 'post',
  url: '....',
  params: {'HTTP_CONTENT_LANGUAGE': self.language},
  headers: {'header1': value}
})

How can I quickly and easily convert spreadsheet data to JSON?

Assuming you really mean easiest and are not necessarily looking for a way to do this programmatically, you can do this:

  1. Add, if not already there, a row of "column Musicians" to the spreadsheet. That is, if you have data in columns such as:

    Rory Gallagher      Guitar
    Gerry McAvoy        Bass
    Rod de'Ath          Drums
    Lou Martin          Keyboards
    Donkey Kong Sioux   Self-Appointed Semi-official Stomper
    

    Note: you might want to add "Musician" and "Instrument" in row 0 (you might have to insert a row there)

  2. Save the file as a CSV file.

  3. Copy the contents of the CSV file to the clipboard

  4. Go to http://www.convertcsv.com/csv-to-json.htm

  5. Verify that the "First row is column names" checkbox is checked

  6. Paste the CSV data into the content area

  7. Mash the "Convert CSV to JSON" button

    With the data shown above, you will now have:

    [
      {
        "MUSICIAN":"Rory Gallagher",
        "INSTRUMENT":"Guitar"
      },
      {
        "MUSICIAN":"Gerry McAvoy",
        "INSTRUMENT":"Bass"
      },
      {
        "MUSICIAN":"Rod D'Ath",
        "INSTRUMENT":"Drums"
      },
      {
        "MUSICIAN":"Lou Martin",
        "INSTRUMENT":"Keyboards"
      }
      {
        "MUSICIAN":"Donkey Kong Sioux",
        "INSTRUMENT":"Self-Appointed Semi-Official Stomper"
      }
    ]
    

    With this simple/minimalistic data, it's probably not required, but with large sets of data, it can save you time and headache in the proverbial long run by checking this data for aberrations and abnormalcy.

  8. Go here: http://jsonlint.com/

  9. Paste the JSON into the content area

  10. Pres the "Validate" button.

If the JSON is good, you will see a "Valid JSON" remark in the Results section below; if not, it will tell you where the problem[s] lie so that you can fix it/them.

openCV program compile error "libopencv_core.so.2.4: cannot open shared object file: No such file or directory" in ubuntu 12.04

You haven't put the shared library in a location where the loader can find it. look inside the /usr/local/opencv and /usr/local/opencv2 folders and see if either of them contains any shared libraries (files beginning in lib and usually ending in .so). when you find them, create a file called /etc/ld.so.conf.d/opencv.conf and write to it the paths to the folders where the libraries are stored, one per line.

for example, if the libraries were stored under /usr/local/opencv/libopencv_core.so.2.4 then I would write this to my opencv.conf file:

/usr/local/opencv/

Then run

sudo ldconfig -v

If you can't find the libraries, try running

sudo updatedb && locate libopencv_core.so.2.4

in a shell. You don't need to run updatedb if you've rebooted since compiling OpenCV.

References:

About shared libraries on Linux: http://www.eyrie.org/~eagle/notes/rpath.html

About adding the OpenCV shared libraries: http://opencv.willowgarage.com/wiki/InstallGuide_Linux

How to select all records from one table that do not exist in another table?

This is pure set theory which you can achieve with the minus operation.

select id, name from table1
minus
select id, name from table2

Find unused npm packages in package.json

The script from gombosg is much better then npm-check.
I have modified a little bit, so devdependencies in node_modules will also be found.
example sass never used, but needed in sass-loader

#!/bin/bash
DIRNAME=${1:-.}
cd $DIRNAME

FILES=$(mktemp)
PACKAGES=$(mktemp)

# use fd
# https://github.com/sharkdp/fd

function check {
    cat package.json \
        | jq "{} + .$1 | keys" \
        | sed -n 's/.*"\(.*\)".*/\1/p' > $PACKAGES
    echo "--------------------------"
    echo "Checking $1..."
    fd '(js|ts|json)$' -t f > $FILES
    while read PACKAGE
    do
        if [ -d "node_modules/${PACKAGE}" ]; then
            fd  -t f '(js|ts|json)$' node_modules/${PACKAGE} >> $FILES
        fi
        RES=$(cat $FILES | xargs -I {} egrep -i "(import|require|loader|plugins|${PACKAGE}).*['\"](${PACKAGE}|.?\d+)[\"']" '{}' | wc -l)

        if [ $RES = 0 ]
        then
            echo -e "UNUSED\t\t $PACKAGE"
        else
            echo -e "USED ($RES)\t $PACKAGE"
        fi
    done < $PACKAGES
}

check "dependencies"
check "devDependencies"
check "peerDependencies"

Result with original script:

--------------------------
Checking dependencies...
UNUSED           jquery
--------------------------
Checking devDependencies...
UNUSED           @types/jquery
UNUSED           @types/jqueryui
USED (1)         autoprefixer
USED (1)         awesome-typescript-loader
USED (1)         cache-loader
USED (1)         css-loader
USED (1)         d3
USED (1)         mini-css-extract-plugin
USED (1)         postcss-loader
UNUSED           sass
USED (1)         sass-loader
USED (1)         terser-webpack-plugin
UNUSED           typescript
UNUSED           webpack
UNUSED           webpack-cli
USED (1)         webpack-fix-style-only-entries

and the modified:

Checking dependencies...
USED (5)         jquery
--------------------------
Checking devDependencies...
UNUSED           @types/jquery
UNUSED           @types/jqueryui
USED (1)         autoprefixer
USED (1)         awesome-typescript-loader
USED (1)         cache-loader
USED (1)         css-loader
USED (2)         d3
USED (1)         mini-css-extract-plugin
USED (1)         postcss-loader
USED (3)         sass
USED (1)         sass-loader
USED (1)         terser-webpack-plugin
USED (16)        typescript
USED (16)        webpack
USED (2)         webpack-cli
USED (2)         webpack-fix-style-only-entries

FormData.append("key", "value") is not working

New in Chrome 50+ and Firefox 39+ (resp. 44+):

  • formdata.entries() (combine with Array.from() for debugability)
  • formdata.get(key)
  • and more very useful methods

Original answer:

What I usually do to 'debug' a FormData object, is just send it (anywhere!) and check the browser logs (eg. Chrome devtools' Network tab).

You don't need a/the same Ajax framework. You don't need any details. Just send it:

var xhr = new XMLHttpRequest;
xhr.open('POST', '/', true);
xhr.send(data);

Easy.

How to use Visual Studio Code as Default Editor for Git

on windows 10 using the 64bit insiders edition the command should be:

git config --global core.editor "'C:\Program Files\Microsoft VS Code Insiders\bin\code-insiders.cmd'"

you can also rename the 'code-insiders.cmd' to 'code.cmd' in the 'Program Files' directory, in this way you can now use the command 'code .' to start editing the files on the . directory

What is the recommended project structure for spring boot rest projects?

config - class which will read from property files

cache - caching mechanism class files

constants - constant defined class

controller - controller class

exception - exception class

model - pojos classes will be present

security - security classes

service - Impl classes

util - utility classes

validation - validators classes

bootloader - main class

"Unable to get the VLookup property of the WorksheetFunction Class" error

I was having the same problem. It seems that passing Me.ComboBox1.Value as an argument for the Vlookup function is causing the issue. What I did was assign this value to a double and then put it into the Vlookup function.

Dim x As Double
x = Me.ComboBox1.Value
Me.TextBox1.Value = Application.WorksheetFunction.VLookup(x, Worksheets("Sheet3").Range("Names"), 2, False) 

Or, for a shorter method, you can just convert the type within the Vlookup function using Cdbl(<Value>).

So it would end up being

Me.TextBox1.Value = Application.WorksheetFunction.VLookup(Cdbl(Me.ComboBox1.Value), Worksheets("Sheet3").Range("Names"), 2, False) 

Strange as it may sound, it works for me.

Hope this helps.

How to create multidimensional array

I've created an npm module to do this with some added flexibility:

// create a 3x3 array
var twodimensional = new MultiDimensional([3, 3])

// create a 3x3x4 array
var threedimensional = new MultiDimensional([3, 3, 4])

// create a 4x3x4x2 array
var fourdimensional = new MultiDimensional([4, 3, 4, 2])

// etc...

You can also initialize the positions with any value:

// create a 3x4 array with all positions set to 0
var twodimensional = new MultiDimensional([3, 4], 0)

// create a 3x3x4 array with all positions set to 'Default String'
var threedimensionalAsStrings = new MultiDimensional([3, 3, 4], 'Default String')

Or more advanced:

// create a 3x3x4 array with all positions set to a unique self-aware objects.
var threedimensional = new MultiDimensional([3, 3, 4], function(position, multidimensional) {
    return {
        mydescription: 'I am a cell at position ' + position.join(),
        myposition: position,
        myparent: multidimensional
    }
})

Get and set values at positions:

// get value
threedimensional.position([2, 2, 2])

// set value
threedimensional.position([2, 2, 2], 'New Value')

How do I make case-insensitive queries on Mongodb?

An easy way would be to use $toLower as below.

db.users.aggregate([
    {
        $project: {
            name: { $toLower: "$name" }
        }
    },
    {
        $match: {
            name: the_name_to_search
        }
    }
])

How to view/delete local storage in Firefox?

As 'localStorage' is just another object, you can: create, view, and edit it in the 'Console'. Simply enter 'localStorage' as a command and press enter, it'll display a string containing the key-value pairs of localStorage (Tip: Click on that string for formatted output, i.e. to display each key-value pair in each line).

How do I validate a date in this format (yyyy-mm-dd) using jquery?

You could also just use regular expressions to accomplish a slightly simpler job if this is enough for you (e.g. as seen in [1]).

They are build in into javascript so you can use them without any libraries.

function isValidDate(dateString) {
  var regEx = /^\d{4}-\d{2}-\d{2}$/;
  return dateString.match(regEx) != null;
}

would be a function to check if the given string is four numbers - two numbers - two numbers (almost yyyy-mm-dd). But you can do even more with more complex expressions, e.g. check [2].

isValidDate("23-03-2012") // false
isValidDate("1987-12-24") // true
isValidDate("22-03-1981") // false
isValidDate("0000-00-00") // true

Find out time it took for a python script to complete execution

import time 

startTime = time.time()
# Your code here !
print ('The script took {0} second !'.format(time.time() - startTime))

The previous code works for me with no problem !

Align vertically using CSS 3

Try this also work perfectly:

html:

   <body>
    <div id="my-div"></div>
   </body>

css:

#my-div {               
    position: absolute;
    height: 100px;
    width: 100px;    
    left: 50%;
    top: 50%;
    background: red;
    display: table-cell;
    vertical-align: middle

}

Getting rid of bullet points from <ul>

Put

<style type="text/css">
 ul#otis {
     list-style-type: none;
   }
</style>

immediately before the list to test it out. Or

<ul style="list-style-type: none;">

How to declare Return Types for Functions in TypeScript

You are correct - here is a fully working example - you'll see that var result is implicitly a string because the return type is specified on the greet() function. Change the type to number and you'll get warnings.

class Greeter {
    greeting: string;
    constructor (message: string) {
        this.greeting = message;
    }
    greet() : string {
        return "Hello, " + this.greeting;
    }
} 

var greeter = new Greeter("Hi");
var result = greeter.greet();

Here is the number example - you'll see red squiggles in the playground editor if you try this:

greet() : number {
    return "Hello, " + this.greeting;
}

Basic HTTP authentication with Node and Express 4

function auth (req, res, next) {
  console.log(req.headers);
  var authHeader = req.headers.authorization;
  if (!authHeader) {
      var err = new Error('You are not authenticated!');
      res.setHeader('WWW-Authenticate', 'Basic');
      err.status = 401;
      next(err);
      return;
  }
  var auth = new Buffer.from(authHeader.split(' ')[1], 'base64').toString().split(':');
  var user = auth[0];
  var pass = auth[1];
  if (user == 'admin' && pass == 'password') {
      next(); // authorized
  } else {
      var err = new Error('You are not authenticated!');
      res.setHeader('WWW-Authenticate', 'Basic');      
      err.status = 401;
      next(err);
  }
}
app.use(auth);

Why .NET String is immutable?

string management is an expensive process. keeping strings immutable allows repeated strings to be reused, rather than re-created.

Reading and writing environment variables in Python?

First things first :) reading books is an excellent approach to problem solving; it's the difference between band-aid fixes and long-term investments in solving problems. Never miss an opportunity to learn. :D

You might choose to interpret the 1 as a number, but environment variables don't care. They just pass around strings:

   The argument envp is an array of character pointers to null-
   terminated strings. These strings shall constitute the
   environment for the new process image. The envp array is
   terminated by a null pointer.

(From environ(3posix).)

You access environment variables in python using the os.environ dictionary-like object:

>>> import os
>>> os.environ["HOME"]
'/home/sarnold'
>>> os.environ["PATH"]
'/home/sarnold/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games'
>>> os.environ["PATH"] = os.environ["PATH"] + ":/silly/"
>>> os.environ["PATH"]
'/home/sarnold/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/silly/'

What are the "spec.ts" files generated by Angular CLI for?

The .spec.ts files are for unit tests for individual components. You can run Karma task runner through ng test. In order to see code coverage of unit test cases for particular components run ng test --code-coverage

Jquery array.push() not working

Your HTML should include quotes for attributes : http://jsfiddle.net/dKWnb/4/

Not required when using a HTML5 doctype - thanks @bazmegakapa

You create the array each time and add a value to it ... its working as expected ?

Moving the array outside of the live() function works fine :

var myarray = []; // more efficient than new Array()
$("#test").live("click",function() {
        myarray.push($("#drop").val());
        alert(myarray);
});

http://jsfiddle.net/dKWnb/5/

Also note that in later versions of jQuery v1.7 -> the live() method is deprecated and replaced by the on() method.

Get: TypeError: 'dict_values' object does not support indexing when using python 3.2.3

In Python 3, dict.values() (along with dict.keys() and dict.items()) returns a view, rather than a list. See the documentation here. You therefore need to wrap your call to dict.values() in a call to list like so:

v = list(d.values())
{names[i]:v[i] for i in range(len(names))}

How do I change the figure size for a seaborn plot?

You can set the context to be poster or manually set fig_size.

import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt

np.random.seed(0)
n, p = 40, 8
d = np.random.normal(0, 2, (n, p))
d += np.log(np.arange(1, p + 1)) * -5 + 10


# plot
sns.set_style('ticks')
fig, ax = plt.subplots()
# the size of A4 paper
fig.set_size_inches(11.7, 8.27)
sns.violinplot(data=d, inner="points", ax=ax)    
sns.despine()

fig.savefig('example.png')

enter image description here

Invalid use side-effecting operator Insert within a function

Disclaimer: This is not a solution, it is more of a hack to test out something. User-defined functions cannot be used to perform actions that modify the database state.

I found one way to make insert or update using sqlcmd.exe so you need just to replace the code inside @sql variable.

CREATE FUNCTION [dbo].[_tmp_func](@orderID NVARCHAR(50))
RETURNS INT
AS
BEGIN
DECLARE @sql varchar(4000), @cmd varchar(4000)
SELECT @sql = 'INSERT INTO _ord (ord_Code) VALUES (''' + @orderID + ''') '
SELECT @cmd = 'sqlcmd -S ' + @@servername +
              ' -d ' + db_name() + ' -Q "' + @sql + '"'
EXEC master..xp_cmdshell @cmd, 'no_output'
RETURN 1
END

How do I fix the error "Only one usage of each socket address (protocol/network address/port) is normally permitted"?

You are debugging two or more times. so the application may run more at a time. Then only this issue will occur. You should close all debugging applications using task-manager, Then debug again.

How do I configure the proxy settings so that Eclipse can download new plugins?

For me, I go to \eclipse\configuration.settings\org.eclipse.core.net.prefs set the property systemProxiesEnabled to true manually and restart eclipse.

Java: Detect duplicates in ArrayList?

I needed to do a similar operation for a Stream, but couldn't find a good example. Here's what I came up with.

public static <T> boolean areUnique(final Stream<T> stream) {
    final Set<T> seen = new HashSet<>();
    return stream.allMatch(seen::add);
}

This has the advantage of short-circuiting when duplicates are found early rather than having to process the whole stream and isn't much more complicated than just putting everything in a Set and checking the size. So this case would roughly be:

List<T> list = ...
boolean allDistinct = areUnique(list.stream());

How do you use the Immediate Window in Visual Studio?

The Immediate window is used to debug and evaluate expressions, execute statements, print variable values, and so forth. It allows you to enter expressions to be evaluated or executed by the development language during debugging.

To display Immediate Window, choose Debug >Windows >Immediate or press Ctrl-Alt-I

enter image description here

Here is an example with Immediate Window:

int Sum(int x, int y) { return (x + y);}
void main(){
int a, b, c;
a = 5;
b = 7;
c = Sum(a, b);
char temp = getchar();}

add breakpoint

enter image description here

call commands

enter image description here

https://msdn.microsoft.com/en-us/library/f177hahy.aspx

OpenVPN failed connection / All TAP-Win32 adapters on this system are currently in use

I found a solution to this. It's bloody witchcraft, but it works.

When you install the client, open Control Panel > Network Connections.

You'll see a disabled network connection that was added by the TAP installer (Local Area Connection 3 or some such).

Right Click it, click Enable.

The device will not reset itself to enabled, but that's ok; try connecting w/ the client again. It'll work.

How to post data in PHP using file_get_contents?

An alternative, you can also use fopen

$params = array('http' => array(
    'method' => 'POST',
    'content' => 'toto=1&tata=2'
));

$ctx = stream_context_create($params);
$fp = @fopen($sUrl, 'rb', false, $ctx);
if (!$fp)
{
    throw new Exception("Problem with $sUrl, $php_errormsg");
}

$response = @stream_get_contents($fp);
if ($response === false) 
{
    throw new Exception("Problem reading data from $sUrl, $php_errormsg");
}

Git push error: Unable to unlink old (Permission denied)

I had the same issue and none of the solutions above worked for me. I deleted the offending folder. Then:

git reset --hard

Deleted any lingering files to clean up the git status, then did:

git pull

It finally worked.

NOTE: If the folder was, for instance, a public folder with build files, remember to rebuild the files

How do I properly set the permgen size?

Completely removed from java 8 +
Partially removed from java 7 (interned Strings for example)
source

Sorting Python list based on the length of the string

When you pass a lambda to sort, you need to return an integer, not a boolean. So your code should instead read as follows:

xs.sort(lambda x,y: cmp(len(x), len(y)))

Note that cmp is a builtin function such that cmp(x, y) returns -1 if x is less than y, 0 if x is equal to y, and 1 if x is greater than y.

Of course, you can instead use the key parameter:

xs.sort(key=lambda s: len(s))

This tells the sort method to order based on whatever the key function returns.

EDIT: Thanks to balpha and Ruslan below for pointing out that you can just pass len directly as the key parameter to the function, thus eliminating the need for a lambda:

xs.sort(key=len)

And as Ruslan points out below, you can also use the built-in sorted function rather than the list.sort method, which creates a new list rather than sorting the existing one in-place:

print(sorted(xs, key=len))

HTML5 image icon to input placeholder

  1. You can set it as background-image and use text-indent or a padding to shift the text to the right.
  2. You can break it up into two elements.

Honestly, I would avoid usage of HTML5/CSS3 without a good fallback. There are just too many people using old browsers that don't support all the new fancy stuff. It will take a while before we can drop the fallback, unfortunately :(

The first method I mentioned is the safest and easiest. Both ways requires Javascript to hide the icon.

CSS:

input#search {
    background-image: url(bg.jpg);
    background-repeat: no-repeat;
    text-indent: 20px;
}

HTML:

<input type="text" id="search" name="search" onchange="hideIcon(this);" value="search" />

Javascript:

function hideIcon(self) {
    self.style.backgroundImage = 'none';
}

September 25h, 2013

I can't believe I said "Both ways requires JavaScript to hide the icon.", because this is not entirely true.

The most common timing to hide placeholder text is on change, as suggested in this answer. For icons however it's okay to hide them on focus which can be done in CSS with the active pseudo-class.

#search:active { background-image: none; }

Heck, using CSS3 you can make it fade away!

http://jsfiddle.net/2tTxE/


November 5th, 2013

Of course, there's the CSS3 ::before pseudo-elements too. Beware of browser support though!

            Chrome  Firefox     IE      Opera   Safari
:before     (yes)   1.0         8.0     4       4.0
::before    (yes)   1.5         9.0     7       4.0

https://developer.mozilla.org/en-US/docs/Web/CSS/::before

Css pseudo classes input:not(disabled)not:[type="submit"]:focus

Your syntax is pretty screwy.

Change this:

input:not(disabled)not:[type="submit"]:focus{

to:

input:not(:disabled):not([type="submit"]):focus{

Seems that many people don't realize :enabled and :disabled are valid CSS selectors...

Compare 2 JSON objects

Simply parsing the JSON and comparing the two objects is not enough because it wouldn't be the exact same object references (but might be the same values).

You need to do a deep equals.

From http://threebit.net/mail-archive/rails-spinoffs/msg06156.html - which seems the use jQuery.

Object.extend(Object, {
   deepEquals: function(o1, o2) {
     var k1 = Object.keys(o1).sort();
     var k2 = Object.keys(o2).sort();
     if (k1.length != k2.length) return false;
     return k1.zip(k2, function(keyPair) {
       if(typeof o1[keyPair[0]] == typeof o2[keyPair[1]] == "object"){
         return deepEquals(o1[keyPair[0]], o2[keyPair[1]])
       } else {
         return o1[keyPair[0]] == o2[keyPair[1]];
       }
     }).all();
   }
});

Usage:

var anObj = JSON.parse(jsonString1);
var anotherObj= JSON.parse(jsonString2);

if (Object.deepEquals(anObj, anotherObj))
   ...

How to adjust text font size to fit textview

I had this pain in my projects for soooo long until I found this library:

compile 'me.grantland:autofittextview:0.2.+'

You just need to add the xml by your needs and it's done. For example:

<me.grantland.widget.AutofitTextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:singleLine="true"
android:maxLines="2"
android:textSize="40sp"
autofit:minTextSize="16sp"
/>

TypeScript-'s Angular Framework Error - "There is no directive with exportAs set to ngForm"

(Just in case someone else is blind like me) form FTW! Make sure to use <form> tag

wont work:

<div (ngSubmit)="search()" #f="ngForm" class="input-group">
    <span class="input-group-btn">
      <button class="btn btn-secondary" type="submit">Go!</button>
    </span>
    <input type="text" ngModel class="form-control" name="search" placeholder="Search..." aria-label="Search...">
</div>

works like charm:

 <form (ngSubmit)="search()" #f="ngForm" class="input-group">
            <span class="input-group-btn">
              <button class="btn btn-secondary" type="submit">Go!</button>
            </span>
            <input type="text" ngModel class="form-control" name="search" placeholder="Search..." aria-label="Search...">
</form>

How do I install imagemagick with homebrew?

brew install imagemagick

Don't forget to install also gs which is a dependency if you want to convert pdf to images for example :

brew install ghostscript

Constructing pandas DataFrame from values in variables gives "ValueError: If using all scalar values, you must pass an index"

You need to provide iterables as the values for the Pandas DataFrame columns:

df2 = pd.DataFrame({'A':[a],'B':[b]})

Setting DEBUG = False causes 500 Error

For what it's worth - I was getting a 500 with DEBUG = False on some pages only. Tracing back the exception with pdb revealed a missing asset (I suspect the {% static ... %} template tag was the culprit for the 500.

Remove non-ASCII characters from CSV

As an alternative to sed or perl you may consider to use ed(1) and POSIX character classes.

Note: ed(1) reads the entire file into memory to edit it in-place, so for really large files you should use sed -i ..., perl -i ...

# see:
# - http://wiki.bash-hackers.org/doku.php?id=howto:edit-ed
# - http://en.wikipedia.org/wiki/Regular_expression#POSIX_character_classes

# test
echo $'aaa \177 bbb \200 \214 ccc \254 ddd\r\n' > testfile
ed -s testfile <<< $',l' 
ed -s testfile <<< $'H\ng/[^[:graph:][:space:][:cntrl:]]/s///g\nwq'
ed -s testfile <<< $',l'

How to dynamically create columns in datatable and assign values to it?

What have you tried, what was the problem?

Creating DataColumns and add values to a DataTable is straight forward:

Dim dt = New DataTable()
Dim dcID = New DataColumn("ID", GetType(Int32))
Dim dcName = New DataColumn("Name", GetType(String))
dt.Columns.Add(dcID)
dt.Columns.Add(dcName)
For i = 1 To 1000
    dt.Rows.Add(i, "Row #" & i)
Next

Edit:

If you want to read a xml file and load a DataTable from it, you can use DataTable.ReadXml.

Assign one struct to another in C

Did you mean "Complex" as in complex number with real and imaginary parts? This seems unlikely, so if not you'd have to give an example since "complex" means nothing specific in terms of the C language.

You will get a direct memory copy of the structure; whether that is what you want depends on the structure. For example if the structure contains a pointer, both copies will point to the same data. This may or may not be what you want; that is down to your program design.

To perform a 'smart' copy (or a 'deep' copy), you will need to implement a function to perform the copy. This can be very difficult to achieve if the structure itself contains pointers and structures that also contain pointers, and perhaps pointers to such structures (perhaps that's what you mean by "complex"), and it is hard to maintain. The simple solution is to use C++ and implement copy constructors and assignment operators for each structure or class, then each one becomes responsible for its own copy semantics, you can use assignment syntax, and it is more easily maintained.

JQuery, Spring MVC @RequestBody and JSON - making it work together

If you do not want to configure the message converters yourself, you can use either @EnableWebMvc or <mvc:annotation-driven />, add Jackson to the classpath and Spring will give you both JSON, XML (and a few other converters) by default. Additionally, you will get some other commonly used features for conversion, formatting and validation.

How to pass query parameters with a routerLink

queryParams

queryParams is another input of routerLink where they can be passed like

<a [routerLink]="['../']" [queryParams]="{prop: 'xxx'}">Somewhere</a>

fragment

<a [routerLink]="['../']" [queryParams]="{prop: 'xxx'}" [fragment]="yyy">Somewhere</a>

routerLinkActiveOptions

To also get routes active class set on parent routes:

[routerLinkActiveOptions]="{ exact: false }"

To pass query parameters to this.router.navigate(...) use

let navigationExtras: NavigationExtras = {
  queryParams: { 'session_id': sessionId },
  fragment: 'anchor'
};

// Navigate to the login page with extras
this.router.navigate(['/login'], navigationExtras);

See also https://angular.io/guide/router#query-parameters-and-fragments

Cannot execute RUN mkdir in a Dockerfile

You can also simply use

WORKDIR /var/www/app

It will automatically create the folders if they don't exist.

Then switch back to the directory you need to be in.

How do I convert between ISO-8859-1 and UTF-8 in Java?

Here is an easy way with String output (I created a method to do this):

public static String (String input){
    String output = "";
    try {
        /* From ISO-8859-1 to UTF-8 */
        output = new String(input.getBytes("ISO-8859-1"), "UTF-8");
        /* From UTF-8 to ISO-8859-1 */
        output = new String(input.getBytes("UTF-8"), "ISO-8859-1");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    return output;
}
// Example
input = "Música";
output = "Música";

Authentication failed because remote party has closed the transport stream

I would advise against restricting the SecurityProtocol to TLS 1.1.

The recommended solution is to use

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls

Another option is add the following Registry key:

Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319 
Value: SchUseStrongCrypto 

It is worth noting that .NET 4.6 will use the correct protocol by default and does not require either solution.

XAMPP keeps showing Dashboard/Welcome Page instead of the Configuration Page

my suggestion: Choose a different version. I had the same problem you have deinstalled v5.6.11, downloaded and installed v5.6.3, works fine for me.

cheers!

How to Update Multiple Array Elements in mongodb

I've been looking for a solution to this using the newest driver for C# 3.6 and here's the fix I eventually settled on. The key here is using "$[]" which according to MongoDB is new as of version 3.6. See https://docs.mongodb.com/manual/reference/operator/update/positional-all/#up.S[] for more information.

Here's the code:

{
   var filter = Builders<Scene>.Filter.Where(i => i.ID != null);
   var update = Builders<Scene>.Update.Unset("area.$[].discoveredBy");
   var result = collection.UpdateMany(filter, update, new UpdateOptions { IsUpsert = true});
}

For more context see my original post here: Remove array element from ALL documents using MongoDB C# driver

for or while loop to do something n times

This is lighter weight than xrange (and the while loop) since it doesn't even need to create the int objects. It also works equally well in Python2 and Python3

from itertools import repeat
for i in repeat(None, 10):
    do_sth()

Get the (last part of) current directory name in C#

rather then using the '/' for the call to split, better to use the Path.DirectorySeparatorChar :

like so:

path.split(Path.DirectorySeparatorChar).Last() 

java.lang.NoSuchMethodError: org.apache.commons.codec.binary.Base64.encodeBase64String() in Java EE application

Some Google tooling such as GWT has an embedded version of commons-codec with a pre-1.4 Base64 class. You may need to make such tooling JARs inaccessible to your code by refactoring your project such that only the parts of your code that need that tooling can see the dependency.

How to create a hash or dictionary object in JavaScript

You want to create an Object, not an Array.

Like so,

var Map = {};

Map['key1'] = 'value1';
Map['key2'] = 'value2';

You can check if the key exists in multiple ways:

Map.hasOwnProperty(key);
Map[key] != undefined // For illustration // Edit, remove null check
if (key in Map) ...

Does Python have a ternary conditional operator?

if variable is defined and you want to check if it has value you can just a or b

def test(myvar=None):
    # shorter than: print myvar if myvar else "no Input"
    print myvar or "no Input"

test()
test([])
test(False)
test('hello')
test(['Hello'])
test(True)

will output

no Input
no Input
no Input
hello
['Hello']
True

How do you switch pages in Xamarin.Forms?

If you do not want to go the previous page i.e. do not let the user go back to the login screen once authorization is done, then you can use;

 App.Current.MainPage = new HomePage();

If you want to enable back functionality, just use

Navigation.PushModalAsync(new HomePage())

Most Useful Attributes

In Hofstadtian spirit, the [Attribute] attribute is very useful, since it's how you create your own attributes. I've used attributes instead of interfaces to implement plugin systems, add descriptions to Enums, simulate multiple dispatch and other tricks.

SQLite add Primary Key

As long as you are using CREATE TABLE, if you are creating the primary key on a single field, you can use:

CREATE TABLE mytable (
field1 TEXT,
field2 INTEGER PRIMARY KEY,
field3 BLOB,
);

With CREATE TABLE, you can also always use the following approach to create a primary key on one or multiple fields:

CREATE TABLE mytable (
field1 TEXT,
field2 INTEGER,
field3 BLOB,
PRIMARY KEY (field2, field1)
);

Reference: http://www.sqlite.org/lang_createtable.html

This answer does not address table alteration.

How to create custom spinner like border around the spinner with down triangle on the right side?

To change only "background" (add corners, change color, ....) you can put it into FrameLayout with wanted background drawable, else you need to make nine patch background for to not lose spinner arrow. Spinner background is transparent.

How do I find the data directory for a SQL Server instance?

From the GUI: open your server properties, go to Database Settings, and see Database default locations.

Note that you can drop your database files wherever you like, though it seems cleaner to keep them in the default directory.

Convert a String In C++ To Upper Case

My solution (clearing 6th bit for alpha):

#include <ctype.h>

inline void toupper(char* str)
{
    while (str[i]) {
        if (islower(str[i]))
            str[i] &= ~32; // Clear bit 6 as it is what differs (32) between Upper and Lowercases
        i++;
    }
}

Elegant way to report missing values in a data.frame

ExPanDaR’s package function prepare_missing_values_graph can be used to explore panel data:

enter image description here

jquery how to catch enter key and change event to tab

$('input').live("keypress", function(e) {
            /* ENTER PRESSED*/
            if (e.keyCode == 13) {
                /* FOCUS ELEMENT */
                var inputs = $(this).parents("form").eq(0).find(":input:visible");
                var idx = inputs.index(this);

                if (idx == inputs.length - 1) {
                    inputs[0].select()
                } else {
                    inputs[idx + 1].focus(); //  handles submit buttons
                    inputs[idx + 1].select();
                }
                return false;
            }
        });

visible input cann't be focused.

Spring MVC How take the parameter value of a GET HTTP Request in my controller method?

You could also use a URI template. If you structured your request into a restful URL Spring could parse the provided value from the url.

HTML

<li>
    <a id="byParameter" 
       class="textLink" href="<c:url value="/mapping/parameter/bar />">By path, method,and
           presence of parameter</a>
</li>

Controller

@RequestMapping(value="/mapping/parameter/{foo}", method=RequestMethod.GET)
public @ResponseBody String byParameter(@PathVariable String foo) {
    //Perform logic with foo
    return "Mapped by path + method + presence of query parameter! (MappingController)";
}

Spring URI Template Documentation

Disabling Log4J Output in Java

If you want to turn off logging programmatically then use

List<Logger> loggers = Collections.<Logger>list(LogManager.getCurrentLoggers());
loggers.add(LogManager.getRootLogger());
for ( Logger logger : loggers ) {
    logger.setLevel(Level.OFF);
}

Post request with Wget?

Wget currently only supports x-www-form-urlencoded data. --post-file is not for transmitting files as form attachments, it expects data with the form: key=value&otherkey=example.

--post-data and --post-file work the same way: the only difference is that --post-data allows you to specify the data in the command line, while --post-file allows you to specify the path of the file that contain the data to send.

Here's the documentation:

 --post-data=string
       --post-file=file
           Use POST as the method for all HTTP requests and send the specified data
           in the request body.  --post-data sends string as data, whereas
           --post-file sends the contents of file.  Other than that, they work in
           exactly the same way. In particular, they both expect content of the
           form "key1=value1&key2=value2", with percent-encoding for special
           characters; the only difference is that one expects its content as a
           command-line parameter and the other accepts its content from a file. In
           particular, --post-file is not for transmitting files as form
           attachments: those must appear as "key=value" data (with appropriate
           percent-coding) just like everything else. Wget does not currently
           support "multipart/form-data" for transmitting POST data; only
           "application/x-www-form-urlencoded". Only one of --post-data and
           --post-file should be specified.

Regarding your authentication token, it should either be provided in the header, in the path of the url, or in the data itself. This must be indicated somewhere in the documentation of the service you use. In a POST request, as in a GET request, you must specify the data using keys and values. This way the server will be able to receive multiple information with specific names. It's similar with variables.

Hence, you can't just send a magic token to the server, you also need to specify the name of the key. If the key is "token", then it should be token=YOUR_TOKEN.

wget --post-data 'user=foo&password=bar' http://example.com/auth.php

Also, you should consider using curl if you can because it is easier to send files using it. There are many examples on the Internet for that.

How do I uninstall nodejs installed from pkg (Mac OS X)?

A little convenience script expanding on previous answers.

#!/bin/bash

# Uninstall node.js
# 
# Options:
#
# -d Actually delete files, otherwise the script just _prints_ a command to delete.
# -p Installation prefix. Default /usr/local
# -f BOM file. Default /var/db/receipts/org.nodejs.pkg.bom

CMD="echo sudo rm -fr"
BOM_FILE="/var/db/receipts/org.nodejs.pkg.bom"
PREFIX="/usr/local"

while getopts "dp:f:" arg; do
    case $arg in
        d)
            CMD="sudo rm -fr"
            ;;
        p)
            PREFIX=$arg
            ;;
        f)
            BOM_FILE=$arg
            ;;
    esac
done

lsbom -f -l -s -pf ${BOM_FILE} \
    | while read i; do
          $CMD ${PREFIX}/${i}
      done

$CMD ${PREFIX}/lib/node \
     ${PREFIX}/lib/node_modules \
     ${BOM_FILE}

Save it to file and run with:

# bash filename.sh

What is a "bundle" in an Android application

Bundle:- A mapping from String values to various Parcelable types.

Bundle is generally used for passing data between various activities of android.

when we call onPause() then onStop() and then in reverse order onStop() to onPause().

The saved data that the system uses to restore the previous state is called the "instance state" and is a collection of key-value pairs stored in a Bundle object.

How to use parameters with HttpPost

To set parameters to your HttpPostRequest you can use BasicNameValuePair, something like this :

    HttpClient httpclient;
    HttpPost httpPost;
    ArrayList<NameValuePair> postParameters;
    httpclient = new DefaultHttpClient();
    httpPost = new HttpPost("your login link");


    postParameters = new ArrayList<NameValuePair>();
    postParameters.add(new BasicNameValuePair("param1", "param1_value"));
    postParameters.add(new BasicNameValuePair("param2", "param2_value"));

    httpPost.setEntity(new UrlEncodedFormEntity(postParameters, "UTF-8"));

    HttpResponse response = httpclient.execute(httpPost);

Convert String to Calendar Object in Java

tl;dr

The modern approach uses the java.time classes.

YearMonth.from(
    ZonedDateTime.parse( 
        "Mon Mar 14 16:02:37 GMT 2011" , 
        DateTimeFormatter.ofPattern( "E MMM d HH:mm:ss z uuuu" )
     )
).toString()

2011-03

Avoid legacy date-time classes

The modern way is with java.time classes. The old date-time classes such as Calendar have proven to be poorly-designed, confusing, and troublesome.

Define a custom formatter to match your string input.

String input = "Mon Mar 14 16:02:37 GMT 2011";
DateTimeFormatter f = DateTimeFormatter.ofPattern( "E MMM d HH:mm:ss z uuuu" );

Parse as a ZonedDateTime.

ZonedDateTime zdt = ZonedDateTime.parse( input , f );

You are interested in the year and month. The java.time classes include YearMonth class for that purpose.

YearMonth ym = YearMonth.from( zdt );

You can interrogate for the year and month numbers if needed.

int year = ym.getYear();
int month = ym.getMonthValue();

But the toString method generates a string in standard ISO 8601 format.

String output = ym.toString();

Put this all together.

String input = "Mon Mar 14 16:02:37 GMT 2011";
DateTimeFormatter f = DateTimeFormatter.ofPattern( "E MMM d HH:mm:ss z uuuu" );
ZonedDateTime zdt = ZonedDateTime.parse( input , f );
YearMonth ym = YearMonth.from( zdt );
int year = ym.getYear();
int month = ym.getMonthValue();

Dump to console.

System.out.println( "input: " + input );
System.out.println( "zdt: " + zdt );
System.out.println( "ym: " + ym );

input: Mon Mar 14 16:02:37 GMT 2011

zdt: 2011-03-14T16:02:37Z[GMT]

ym: 2011-03

Live code

See this code running in IdeOne.com.

Conversion

If you must have a Calendar object, you can convert to a GregorianCalendar using new methods added to the old classes.

GregorianCalendar gc = GregorianCalendar.from( zdt );

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to java.time.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

  • Java SE 8 and SE 9 and later
    • Built-in.
    • Part of the standard Java API with a bundled implementation.
    • Java 9 adds some minor features and fixes.
  • Java SE 6 and SE 7
    • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
  • Android

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Trim characters in Java

public static String trim(String value, char c) {

    if (c <= 32) return value.trim();

    int len = value.length();
    int st = 0;
    char[] val = value.toCharArray();    /* avoid getfield opcode */

    while ((st < len) && (val[st] == c)) {
        st++;
    }
    while ((st < len) && (val[len - 1] == c)) {
        len--;
    }
    return ((st > 0) || (len < value.length())) ? value.substring(st, len) : value;
}

How do I import from Excel to a DataSet using Microsoft.Office.Interop.Excel?

Have you seen this one? From http://www.aspspider.com/resources/Resource510.aspx:

public DataTable Import(String path)
{
    Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
    Microsoft.Office.Interop.Excel.Workbook workBook = app.Workbooks.Open(path, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);

    Microsoft.Office.Interop.Excel.Worksheet workSheet = (Microsoft.Office.Interop.Excel.Worksheet)workBook.ActiveSheet;

    int index = 0;
    object rowIndex = 2;

    DataTable dt = new DataTable();
    dt.Columns.Add("FirstName");
    dt.Columns.Add("LastName");
    dt.Columns.Add("Mobile");
    dt.Columns.Add("Landline");
    dt.Columns.Add("Email");
    dt.Columns.Add("ID");

    DataRow row;

    while (((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 1]).Value2 != null)
    {

        row = dt.NewRow();
        row[0] = Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 1]).Value2);
        row[1] = Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 2]).Value2);
        row[2] = Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 3]).Value2);
        row[3] = Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 4]).Value2);
        row[4] = Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[rowIndex, 5]).Value2);
        index++;

        rowIndex = 2 + index;
        dt.Rows.Add(row);
    }
    app.Workbooks.Close();
    return dt;
}

How to list active / open connections in Oracle?

When I'd like to view incoming connections from our application servers to the database I use the following command:

SELECT username FROM v$session 
WHERE username IS NOT NULL 
ORDER BY username ASC;

Simple, but effective.

Check if a number is odd or even in python

One of the simplest ways is to use de modulus operator %. If n % 2 == 0, then your number is even.

Hope it helps,

Detect current device with UI_USER_INTERFACE_IDIOM() in Swift

if/else case:

 if (UIDevice.current.userInterfaceIdiom == UIUserInterfaceIdiom.pad)     
 {
        // Ipad
 }
 else 
 {
       // Iphone
 }

Writing/outputting HTML strings unescaped

You can use

@{ WriteLiteral("html string"); }

What is the difference between .py and .pyc files?

"A program doesn't run any faster when it is read from a ".pyc" or ".pyo" file than when it is read from a ".py" file; the only thing that's faster about ".pyc" or ".pyo" files is the speed with which they are loaded. "

http://docs.python.org/release/1.5.1p1/tut/node43.html

How to convert nanoseconds to seconds using the TimeUnit enum?

TimeUnit is an enum, so you can't create a new one.

The following will convert 1000000000000ns to seconds.

TimeUnit.NANOSECONDS.toSeconds(1000000000000L);

PHP: Call to undefined function: simplexml_load_string()

For Nginx (without apache) and PHP 7.2, installing php7.2-xml wasn't enough. Had to install php7.2-simplexml package to get it to work

So the commands for debian/ubuntu, update packages and install both packages

apt update
apt install php7.2-xml php7.2-simplexml

And restart both Nginx and php

systemctl restart nginx php7.2-fpm