Programs & Examples On #Tunneling

Tunneling is a technique that enables remote access users to connect to a variety of network resources through a public data network.

ssh: check if a tunnel is alive

These are more detailed steps to test or troubleshoot an SSH tunnel. You can use some of them in a script. I'm adding this answer because I had to troubleshoot the link between two applications after they stopped working. Just grepping for the ssh process wasn't enough, as it was still there. And I couldn't use nc -z because that option wasn't available on my incantation of netcat.

Let's start from the beginning. Assume there is a machine, which will be called local with IP address 10.0.0.1 and another, called remote, at 10.0.3.12. I will prepend these hostnames, to the commands below, so it's obvious where they're being executed.

The goal is to create a tunnel that will forward TCP traffic from the loopback address on the remote machine on port 123 to the local machine on port 456. This can be done with the following command, on the local machine:

local:~# ssh -N -R 123:127.0.0.1:456 10.0.3.12

To check that the process is running, we can do:

local:~# ps aux | grep ssh

If you see the command in the output, we can proceed. Otherwise, check that the SSH key is installed in the remote. Note that excluding the username before the remote IP, makes ssh use the current username.

Next, we want to check that the tunnel is open on the remote:

remote:~# netstat | grep 10.0.0.1

We should get an output similar to this:

tcp  0  0  10.0.3.12:ssh  10.0.0.1:45988  ESTABLISHED

Would be nice to actually see some data going through from the remote to the host. This is where netcat comes in. On CentOS it can be installed with yum install nc.

First, open a listening port on the local machine:

local:~# nc -l 127.0.0.1:456

Then make a connection on the remote:

remote:~# nc 127.0.0.1 123

If you open a second terminal to the local machine, you can see the connection. Something like this:

local:~# netstat | grep 456
tcp  0  0 localhost.localdom:456 localhost.localdo:33826 ESTABLISHED
tcp  0  0 localhost.localdo:33826 localhost.localdom:456 ESTABLISHED

Better still, go ahead and type something on the remote:

remote:~# nc 127.0.0.1 8888
Hallo?
anyone there?

You should see this being mirrored on the local terminal:

local:~# nc -l 127.0.0.1:456
Hallo?
anyone there?

The tunnel is working! But what if you have an application, called appname, which is supposed to be listening on port 456 on the local machine? Terminate nc on both sides then run your application. You can check that it's listening on the correct port with this:

local:~# netstat -tulpn | grep LISTEN | grep appname
tcp  0  0  127.0.0.1:456  0.0.0.0:* LISTEN  2964/appname

By the way, running the same command on the remote should show sshd listening on port 127.0.0.1:123.

How to get an object's property's value by property name?

Expanding upon @aquinas:

Get-something | select -ExpandProperty PropertyName

or

Get-something | select -expand PropertyName

or

Get-something | select -exp PropertyName

I made these suggestions for those that might just be looking for a single-line command to obtain some piece of information and wanted to include a real-world example.

In managing Office 365 via PowerShell, here was an example I used to obtain all of the users/groups that had been added to the "BookInPolicy" list:

Get-CalendarProcessing [email protected] | Select -expand BookInPolicy

Just using "Select BookInPolicy" was cutting off several members, so thank you for this information!

Line break in HTML with '\n'

You should consider replacing your line breaks with <br/>. In HTML a line break will only stand for new line in your code.

Alternatively you can use some other HTML markups like placing your lines in paragraphs:

<p>Sample line</p>
<p>Another line</p>

or other wrappers like for instance <div>sample</div> with CSS attribute: display: block.

You can also use <pre>. The content of pre will have its HTML styling ignored. In other words it will display pure HTML with normal \n line breaks.

shorthand If Statements: C#

To use shorthand to get the direction:

int direction = column == 0
                ? 0
                : (column == _gridSize - 1 ? 1 : rand.Next(2));

To simplify the code entirely:

if (column == gridSize - 1 || rand.Next(2) == 1)
{
}
else
{
}

Run exe file with parameters in a batch file

This should work:

start "" "c:\program files\php\php.exe" D:\mydocs\mp\index.php param1 param2

The start command interprets the first argument as a window title if it contains spaces. In this case, that means start considers your whole argument a title and sees no command. Passing "" (an empty title) as the first argument to start fixes the problem.

jQuery - find table row containing table cell containing specific text

$(function(){
    var search = 'foo';
    $("table tr td").filter(function() {
        return $(this).text() == search;
    }).parent('tr').css('color','red');
});

Will turn the text red for rows which have a cell whose text is 'foo'.

Passing two command parameters using a WPF binding

This task can also be solved with a different approach. Instead of programming a converter and enlarging the code in the XAML, you can also aggregate the various parameters in the ViewModel. As a result, the ViewModel then has one more property that contains all parameters.

An example of my current application, which also let me deal with the topic. A generic RelayCommand is required: https://stackoverflow.com/a/22286816/7678085

The ViewModelBase is extended here by a command SaveAndClose. The generic type is a named tuple that represents the various parameters.

public ICommand SaveAndCloseCommand => saveAndCloseCommand ??= new RelayCommand<(IBaseModel Item, Window Window)>
    (execute =>
    {
        execute.Item.Save();
        execute.Window?.Close(); // if NULL it isn't closed.
    },
    canExecute =>
    {
        return canExecute.Item?.IsItemValide ?? false;
    });
private ICommand saveAndCloseCommand;

Then it contains a property according to the generic type:

public (IBaseModel Item, Window Window) SaveAndCloseParameter 
{ 
    get => saveAndCloseParameter ; 
    set 
    {
        SetProperty(ref saveAndCloseParameter, value);
    }
}
private (IBaseModel Item, Window Window) saveAndCloseParameter;

The XAML code of the view then looks like this: (Pay attention to the classic click event)

<Button 
    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Click="ButtonApply_Click" 
    Content="Apply"
    Height="25" Width="100" />
<Button 
    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Click="ButtonSave_Click" 
    Content="Save"
    Height="25" Width="100" />

and in the code behind of the view, then evaluating the click events, which then set the parameter property.

private void ButtonApply_Click(object sender, RoutedEventArgs e)
{
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, null);
}

private void ButtonSave_Click(object sender, RoutedEventArgs e)
{
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, this);
}

Personally, I think that using the click events is not a break with the MVVM pattern. The program flow control is still located in the area of ??the ViewModel.

Running Windows batch file commands asynchronously

Use the START command:

start [programPath]

If the path to the program contains spaces remember to add quotes. In this case you also need to provide a title for the opening console window

start "[title]" "[program path]"

If you need to provide arguments append them at the end (outside the command quotes)

start "[title]" "[program path]" [list of command args]

Use the /b option to avoid opening a new console window (but in that case you cannot interrupt the application using CTRL-C

Download image with JavaScript

As @Ian explained, the problem is that jQuery's click() is not the same as the native one.

Therefore, consider using vanilla-js instead of jQuery:

var a = document.createElement('a');
a.href = "img.png";
a.download = "output.png";
document.body.appendChild(a);
a.click();
document.body.removeChild(a);

Demo

event Action<> vs event EventHandler<>

If you follow the standard event pattern, then you can add an extension method to make the checking of event firing safer/easier. (i.e. the following code adds an extension method called SafeFire() which does the null check, as well as (obviously) copying the event into a separate variable to be safe from the usual null race-condition that can affect events.)

(Although I am in kind of two minds whether you should be using extension methods on null objects...)

public static class EventFirer
{
    public static void SafeFire<TEventArgs>(this EventHandler<TEventArgs> theEvent, object obj, TEventArgs theEventArgs)
        where TEventArgs : EventArgs
    {
        if (theEvent != null)
            theEvent(obj, theEventArgs);
    }
}

class MyEventArgs : EventArgs
{
    // Blah, blah, blah...
}

class UseSafeEventFirer
{
    event EventHandler<MyEventArgs> MyEvent;

    void DemoSafeFire()
    {
        MyEvent.SafeFire(this, new MyEventArgs());
    }

    static void Main(string[] args)
    {
        var x = new UseSafeEventFirer();

        Console.WriteLine("Null:");
        x.DemoSafeFire();

        Console.WriteLine();

        x.MyEvent += delegate { Console.WriteLine("Hello, World!"); };
        Console.WriteLine("Not null:");
        x.DemoSafeFire();
    }
}

jQuery if checkbox is checked

See main difference between ATTR | PROP | IS below:

Source: http://api.jquery.com/attr/

_x000D_
_x000D_
$( "input" )_x000D_
  .change(function() {_x000D_
    var $input = $( this );_x000D_
    $( "p" ).html( ".attr( 'checked' ): <b>" + $input.attr( "checked" ) + "</b><br>" +_x000D_
      ".prop( 'checked' ): <b>" + $input.prop( "checked" ) + "</b><br>" +_x000D_
      ".is( ':checked' ): <b>" + $input.is( ":checked" ) + "</b>" );_x000D_
  })_x000D_
  .change();
_x000D_
p {_x000D_
    margin: 20px 0 0;_x000D_
  }_x000D_
  b {_x000D_
    color: blue;_x000D_
  }
_x000D_
<meta charset="utf-8">_x000D_
  <title>attr demo</title>_x000D_
  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>_x000D_
</head>_x000D_
<body>_x000D_
 _x000D_
<input id="check1" type="checkbox" checked="checked">_x000D_
<label for="check1">Check me</label>_x000D_
<p></p>_x000D_
 _x000D_
_x000D_
 _x000D_
</body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

How to use an environment variable inside a quoted string in Bash

If unsure, you might use the 'cols' request on the terminal, and forget COLUMNS:

COLS=$(tput cols)

Escaping ampersand in URL

You can rather pass your arguments using this encodeURIComponent function so you don't have to worry about passing any special characters.

data: "param1=getAccNos&param2="+encodeURIComponent('Dolce & Gabbana') OR
var someValue = 'Dolce & Gabbana';
data : "param1=getAccNos&param2="+encodeURIComponent(someValue)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent

How to clear PermGen space Error in tomcat

In Tomcat 7.0 Windows Service Installer Version.There is not catalina.bat in /bin . So you need open Tomcat7w.exe in /bin and add blow JVM argument

-XX:PermSize=256m -XX:MaxPermSize=512m

on Java Option in Java Tab, like this. You also add other options.

enter image description here

Another, if you use IntellijIDEA you need add JVM argument in Server Configurations,like this.

enter image description here

How to add http:// if it doesn't exist in the URL

Simply check if there is a protocol (delineated by "://") and add "http://" if there isn't.

if (false === strpos($url, '://')) {
    $url = 'http://' . $url;
}

Note: This may be a simple and straightforward solution, but Jack's answer using parse_url is almost as simple and much more robust. You should probably use that one.

When to use static keyword before global variables?

You should not define global variables in header files. You should define them in .c source file.

  • If global variable is to be visible within only one .c file, you should declare it static.

  • If global variable is to be used across multiple .c files, you should not declare it static. Instead you should declare it extern in header file included by all .c files that need it.

Example:

  • example.h

    extern int global_foo;
    
  • foo.c

    #include "example.h"
    
    int global_foo = 0;
    static int local_foo = 0;
    
    int foo_function()
    {
       /* sees: global_foo and local_foo
          cannot see: local_bar  */
       return 0;
    }
    
  • bar.c

    #include "example.h"
    
    static int local_bar = 0;
    static int local_foo = 0;
    
    int bar_function()
    {
        /* sees: global_foo, local_bar */
        /* sees also local_foo, but it's not the same local_foo as in foo.c
           it's another variable which happen to have the same name.
           this function cannot access local_foo defined in foo.c
        */
        return 0;
    }
    

Get table names using SELECT statement in MySQL

I think it may be helpful to point out that if you want to select tables that contain specific words you can easily do it using the SELECT (instead of SHOW). Below query easily narrows down the search to tables that contain "keyword"

SELECT *
FROM information_schema.tables
WHERE table_name like "%keyword%"

jQuery: get parent, parent id?

$(this).parent().parent().attr('id');

Is how you would get the id of the parent's parent.

EDIT:

$(this).closest('ul').attr('id');

Is a more foolproof solution for your case.

Change action bar color in android

If you use Android default action bar then. If you change from java then some time show previous color.

enter image description here

Example

Then your action bar code inside "app_bar_main". So go inside app_bar_main.xml and just add Background.

Example

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

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="#33691e"   <!--use your color -->
        app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main1" />

Is there a way to "limit" the result with ELOQUENT ORM of Laravel?

If you're looking to paginate results, use the integrated paginator, it works great!

$games = Game::paginate(30);
// $games->results = the 30 you asked for
// $games->links() = the links to next, previous, etc pages

Angular 5 Scroll to top on every Route click

EDIT: For Angular 6+, please use Nimesh Nishara Indimagedara's answer mentioning:

RouterModule.forRoot(routes, {
    scrollPositionRestoration: 'enabled'
});

Original Answer:

If all fails, then create some empty HTML element (eg: div) at the top (or desired scroll to location) with id="top" on template (or parent template):

<div id="top"></div>

And in component:

  ngAfterViewInit() {
    // Hack: Scrolls to top of Page after page view initialized
    let top = document.getElementById('top');
    if (top !== null) {
      top.scrollIntoView();
      top = null;
    }
  }

jquery 3.0 url.indexOf error

Better approach may be a polyfill like this

jQuery.fn.load = function(callback){ $(window).on("load", callback) };

With this you can leave the legacy code untouched. If you use webpack be sure to use script-loader.

imagecreatefromjpeg and similar functions are not working in PHP

After installing php5-gd apache restart is needed.

Sql query to insert datetime in SQL Server

No need to use convert. Simply list it as a quoted date in ISO 8601 format.
Like so:

select * from table1 where somedate between '2000/01/01' and '2099/12/31'

The separator needs to be a / and it needs to be surrounded by single ' quotes.

How does the data-toggle attribute work? (What's its API?)

The data-toggle attribute simple tell Bootstrap what exactly to do by giving it the name of the toggle action it is about to perform on a target element. If you specify collapse. It means bootstrap will collapse or uncollapse the element pointed by data-target of the action you clicked

Note: the target element must have the appropriate class for bootstrap to carry out the action

Source action:
data-toggle = collapse //type of toggle
data-target = #myDiv

Target:
class=collapse //I can collapse
id=myDiv

This is same for other type of toggle actions like tab, modal, dropdown

How to store values from foreach loop into an array?

<?php 
$items = array();
$count = 0;
foreach($group_membership as $i => $username) { 
 $items[$count++] = $username; 
} 
print_r($items); 
?>

Getting the IP address of the current machine using Java

EDIT 1: Updated code, since the previous link, exists no more

import java.io.*;
import java.net.*;

public class GetMyIP {
    public static void main(String[] args) {
        URL url = null;
        BufferedReader in = null;
        String ipAddress = "";
        try {
            url = new URL("http://bot.whatismyipaddress.com");
            in = new BufferedReader(new InputStreamReader(url.openStream()));
            ipAddress = in.readLine().trim();
            /* IF not connected to internet, then
             * the above code will return one empty
             * String, we can check it's length and
             * if length is not greater than zero, 
             * then we can go for LAN IP or Local IP
             * or PRIVATE IP
             */
            if (!(ipAddress.length() > 0)) {
                try {
                    InetAddress ip = InetAddress.getLocalHost();
                    System.out.println((ip.getHostAddress()).trim());
                    ipAddress = (ip.getHostAddress()).trim();
                } catch(Exception exp) {
                    ipAddress = "ERROR";
                }
            }
        } catch (Exception ex) {
            // This try will give the Private IP of the Host.
            try {
                InetAddress ip = InetAddress.getLocalHost();
                System.out.println((ip.getHostAddress()).trim());
                ipAddress = (ip.getHostAddress()).trim();
            } catch(Exception exp) {
                ipAddress = "ERROR";
            }
            //ex.printStackTrace();
        }
        System.out.println("IP Address: " + ipAddress);
    }
}

ACTUAL VERSION: This stopped working

Hopefully this snippet might help you to achieve this :

// Method to get the IP Address of the Host.
private String getIP()
{
    // This try will give the Public IP Address of the Host.
    try
    {
        URL url = new URL("http://automation.whatismyip.com/n09230945.asp");
        BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
        String ipAddress = new String();
        ipAddress = (in.readLine()).trim();
        /* IF not connected to internet, then
         * the above code will return one empty
         * String, we can check it's length and
         * if length is not greater than zero, 
         * then we can go for LAN IP or Local IP
         * or PRIVATE IP
         */
        if (!(ipAddress.length() > 0))
        {
            try
            {
                InetAddress ip = InetAddress.getLocalHost();
                System.out.println((ip.getHostAddress()).trim());
                return ((ip.getHostAddress()).trim());
            }
            catch(Exception ex)
            {
                return "ERROR";
            }
        }
        System.out.println("IP Address is : " + ipAddress);

        return (ipAddress);
    }
    catch(Exception e)
    {
        // This try will give the Private IP of the Host.
        try
        {
            InetAddress ip = InetAddress.getLocalHost();
            System.out.println((ip.getHostAddress()).trim());
            return ((ip.getHostAddress()).trim());
        }
        catch(Exception ex)
        {
            return "ERROR";
        }
    }
}

Spark : how to run spark file from spark shell

To load an external file from spark-shell simply do

:load PATH_TO_FILE

This will call everything in your file.

I don't have a solution for your SBT question though sorry :-)

List distinct values in a vector in R

If the data is actually a factor then you can use the levels() function, e.g.

levels( data$product_code )

If it's not a factor, but it should be, you can convert it to factor first by using the factor() function, e.g.

levels( factor( data$product_code ) )

Another option, as mentioned above, is the unique() function:

unique( data$product_code )

The main difference between the two (when applied to a factor) is that levels will return a character vector in the order of levels, including any levels that are coded but do not occur. unique will return a factor in the order the values first appear, with any non-occurring levels omitted (though still included in levels of the returned factor).

Splitting a string into separate variables

Like this?

$string = 'FirstPart SecondPart'
$a,$b = $string.split(' ')
$a
$b

Dynamically Add Images React Webpack

If you are bundling your code at the server-side, then there is nothing stopping you from requiring assets directly from jsx:

<div>
  <h1>Image</h1>
  <img src={require('./assets/image.png')} />
</div>

Display array values in PHP

the join() function must work for you:

$array = array('apple','banana','ananas');
$string = join(',', $array);
echo $string;

Output :

apple,banana,ananas

Creating Scheduled Tasks

This works for me https://www.nuget.org/packages/ASquare.WindowsTaskScheduler/

It is nicely designed Fluent API.

//This will create Daily trigger to run every 10 minutes for a duration of 18 hours
SchedulerResponse response = WindowTaskScheduler
    .Configure()
    .CreateTask("TaskName", "C:\\Test.bat")
    .RunDaily()
    .RunEveryXMinutes(10)
    .RunDurationFor(new TimeSpan(18, 0, 0))
    .SetStartDate(new DateTime(2015, 8, 8))
    .SetStartTime(new TimeSpan(8, 0, 0))
    .Execute();

Preloading CSS Images

I can confirm that my original code seems to work. I was casually sticking to an image with a wrong path.

Here's a test : http://paragraphe.org/slidetoggletest/test.html

<script>
    var pic = new Image();
    var pic2 = new Image();
    var pic3 = new Image();
    pic.src="images/inputs/input1.png";
    pic2.src="images/inputs/input2.png";
    pic3.src="images/inputs/input3.png";
</script>

Docker - a way to give access to a host USB or serial device?

Adding to the answers above, for those who want a quick way to use an external USB device (HDD, flash drive) working inside docker, and not using priviledged mode:

Find the devpath to your device on the host:

sudo fdisk -l

You can recognize your drive by it's capacity quite easily from the list. Copy this path (for the following example it is /dev/sda2).

Disque /dev/sda2 : 554,5 Go, 57151488 octets, 111624 secteurs
Unités : secteur de 1 × 512 = 512 octets
Taille de secteur (logique / physique) : 512 octets / 512 octets
taille d'E/S (minimale / optimale) : 512 octets / 512 octets

Mount this devpath (preferable to /media):

sudo mount <drive path> /media/<mount folder name>

You can then use this either as a param to docker run like:

docker run -it -v /media/<mount folder name>:/media/<mount folder name>

or in docker compose under volumes:

services:
  whatevermyserviceis:
    volumes:
      - /media/<mount folder name>:/media/<mount folder name>

And now when you run and enter your container, you should be able to access the drive inside the container at /media/<mount folder name>

DISCLAIMER:

  1. This will probably not work for serial devices such as webcams etc. I have only tested this for USB storage drives.
  2. If you need to reconnect and disconnect devices regularly, this method would be annoying, and also would not work unless you reset the mount path and restart the container.
  3. I used docker 17.06 + as prescribed in the docs

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

Yes the culprit is definitely word-wrapping. When I tested your two programs, NetBeans IDE 8.2 gave me the following result.

  1. First Matrix: O and # = 6.03 seconds
  2. Second Matrix: O and B = 50.97 seconds

Looking at your code closely you have used a line break at the end of first loop. But you didn't use any line break in second loop. So you are going to print a word with 1000 characters in the second loop. That causes a word-wrapping problem. If we use a non-word character " " after B, it takes only 5.35 seconds to compile the program. And If we use a line break in the second loop after passing 100 values or 50 values, it takes only 8.56 seconds and 7.05 seconds respectively.

Random r = new Random();
for (int i = 0; i < 1000; i++) {
    for (int j = 0; j < 1000; j++) {
        if(r.nextInt(4) == 0) {
            System.out.print("O");
        } else {
            System.out.print("B");
        }
        if(j%100==0){               //Adding a line break in second loop      
            System.out.println();
        }                    
    }
    System.out.println("");                
}

Another advice is that to change settings of NetBeans IDE. First of all, go to NetBeans Tools and click Options. After that click Editor and go to Formatting tab. Then select Anywhere in Line Wrap Option. It will take almost 6.24% less time to compile the program.

NetBeans Editor Settings

How to add leading zeros for for-loop in shell?

Use the following syntax:

$ for i in {01..05}; do echo "$i"; done
01
02
03
04
05

Disclaimer: Leading zeros only work in >=bash-4.

If you want to use printf, nothing prevents you from putting its result in a variable for further use:

$ foo=$(printf "%02d" 5)
$ echo "${foo}"
05

Suppress command line output

Because error messages often go to stderr not stdout.

Change the invocation to this:

taskkill /im "test.exe" /f >nul 2>&1

and all will be better.

That works because stdout is file descriptor 1, and stderr is file descriptor 2 by convention. (0 is stdin, incidentally.) The 2>&1 copies output file descriptor 2 from the new value of 1, which was just redirected to the null device.

This syntax is (loosely) borrowed from many Unix shells, but you do have to be careful because there are subtle differences between the shell syntax and CMD.EXE.

Update: I know the OP understands the special nature of the "file" named NUL I'm writing to here, but a commenter didn't and so let me digress with a little more detail on that aspect.

Going all the way back to the earliest releases of MSDOS, certain file names were preempted by the file system kernel and used to refer to devices. The earliest list of those names included NUL, PRN, CON, AUX and COM1 through COM4. NUL is the null device. It can always be opened for either reading or writing, any amount can be written on it, and reads always succeed but return no data. The others include the parallel printer port, the console, and up to four serial ports. As of MSDOS 5, there were several more reserved names, but the basic convention was very well established.

When Windows was created, it started life as a fairly thin application switching layer on top of the MSDOS kernel, and thus had the same file name restrictions. When Windows NT was created as a true operating system in its own right, names like NUL and COM1 were too widely assumed to work to permit their elimination. However, the idea that new devices would always get names that would block future user of those names for actual files is obviously unreasonable.

Windows NT and all versions that follow (2K, XP, 7, and now 8) all follow use the much more elaborate NT Namespace from kernel code and to carefully constructed and highly non-portable user space code. In that name space, device drivers are visible through the \Device folder. To support the required backward compatibility there is a special mechanism using the \DosDevices folder that implements the list of reserved file names in any file system folder. User code can brows this internal name space using an API layer below the usual Win32 API; a good tool to explore the kernel namespace is WinObj from the SysInternals group at Microsoft.

For a complete description of the rules surrounding legal names of files (and devices) in Windows, this page at MSDN will be both informative and daunting. The rules are a lot more complicated than they ought to be, and it is actually impossible to answer some simple questions such as "how long is the longest legal fully qualified path name?".

MySQL Update Inner Join tables query

For MySql WorkBench, Please use below :

update emp as a
inner join department b on a.department_id=b.id
set a.department_name=b.name
where a.emp_id in (10,11,12); 

C# ASP.NET Single Sign-On Implementation

There are several Identity providers with SSO support out of the box, also third-party** products.

** The only problem with third party products is that they charge per user/month, and it can be quite expensive.

Some of the tools available and with APIs for .NET are:

If you decide to go with your own implementation, you could use the frameworks below categorized by programming language.

  • C#

    • IdentityServer3 (OAuth/OpenID protocols, OWIN/Katana)
    • IdentityServer4 (OAuth/OpenID protocols, ASP.NET Core)
    • OAuth 2.0 by Okta
  • Javascript

    • passport-openidconnect (node.js)
    • oidc-provider (node.js)
    • openid-client (node.js)
  • Python

    • pyoidc
    • Django OIDC Provider

I would go with IdentityServer4 and ASP.NET Core application, it's easy configurable and you can also add your own authentication provider. It uses OAuth/OpenID protocols which are newer than SAML 2.0 and WS-Federation.

reading from stdin in c++

You have not defined the variable input_line.

Add this:

string input_line;

And add this include.

#include <string>

Here is the full example. I also removed the semi-colon after the while loop, and you should have getline inside the while to properly detect the end of the stream.

#include <iostream>
#include <string>

int main() {
    for (std::string line; std::getline(std::cin, line);) {
        std::cout << line << std::endl;
    }
    return 0;
}

Array Length in Java

It should be:

int a = arr.length;

Parenthesis should be avoided.

How do I populate a JComboBox with an ArrayList?

Check this simple code

import java.util.ArrayList;
import javax.swing.JComboBox;
import javax.swing.JFrame;


public class FirstFrame extends JFrame{

    static JComboBox<ArrayList> mycombo;

    FirstFrame()
    {
        this.setSize(600,500);
        this.setTitle("My combo");
        this.setLayout(null);

        ArrayList<String> names=new ArrayList<String>();   
        names.add("jessy");
        names.add("albert");
        names.add("grace");
        mycombo=new JComboBox(names.toArray());
        mycombo.setBounds(60,32,200,50);
        this.add(mycombo);
        this.setVisible(true); // window visible
    }   

    public static void main(String[] args) {

        FirstFrame frame=new FirstFrame();  

    }

}

How to change progress bar's progress color in Android

It is so simple using attr , if you are dealing with multistyle apps:

try this way:

Declare below attribute attrs.xml

 <attr name="circularProgressTheme" format="reference"></attr>

Paste below code in styles.xml

 <style name="ProgressThemeWhite" parent="ThemeOverlay.AppCompat.Light">
        <item name="colorAccent">#FF0000</item>
    </style>

    <style name="circularProgressThemeWhite">
        <item name="android:theme">@style/ProgressThemeWhite</item>
    </style>


  <style name="AppTheme" parent="Theme.AppCompat.NoActionBar">

   <item name="circularProgressTheme">@style/circularProgressThemeWhite</item>

 </style>

use progress bar like below

  <ProgressBar
        style="?attr/circularProgressTheme"
        android:id="@+id/commonProgress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="visible"/>

How do I install opencv using pip?

In case you use aarch64 platform with ARM64 cpu - and/or docker

On a development board on ARM64, no python-opencv version were found at all

version: NONE. I've had to build from source. This allowed to include CUDA support.

In my case it was already available on the board but it wasn't found on the development environment.

If compiling from source is out of reach, there are Dockers

Of course compiling will take some time (few hours on ARM core), but it is worthy process to know as most open source tools can be built this way in case of issues.

Difference between innerText, innerHTML and value?

The only difference between innerText and innerHTML is that innerText insert string as it is into the element, while innerHTML run it as html content.

_x000D_
_x000D_
const ourstring = 'My name is <b class="name">Satish chandra Gupta</b>.';_x000D_
document.getElementById('innertext').innerText = ourstring;_x000D_
document.getElementById('innerhtml').innerHTML = ourstring;
_x000D_
.name{_x000D_
color:red;_x000D_
}
_x000D_
<h3>Inner text below. It inject string as it is into the element.</h3>_x000D_
<div id="innertext"></div>_x000D_
<br />_x000D_
<h3>Inner html below. It renders the string into the element and treat as part of html document.</h3>_x000D_
<div id="innerhtml"></div>
_x000D_
_x000D_
_x000D_

Converting UTF-8 to ISO-8859-1 in Java - how to keep it as single byte

If you have the correct encoding in the string, you need not do more to get the bytes for another encoding.

public static void main(String[] args) throws Exception {
    printBytes("â");
    System.out.println(
            new String(new byte[] { (byte) 0xE2 }, "ISO-8859-1"));
    System.out.println(
            new String(new byte[] { (byte) 0xC3, (byte) 0xA2 }, "UTF-8"));
}

private static void printBytes(String str) {
    System.out.println("Bytes in " + str + " with ISO-8859-1");
    for (byte b : str.getBytes(StandardCharsets.ISO_8859_1)) {
        System.out.printf("%3X", b);
    }
    System.out.println();
    System.out.println("Bytes in " + str + " with UTF-8");
    for (byte b : str.getBytes(StandardCharsets.UTF_8)) {
        System.out.printf("%3X", b);
    }
    System.out.println();
}

Output:

Bytes in â with ISO-8859-1
 E2
Bytes in â with UTF-8
 C3 A2
â
â

Typing the Enter/Return key using Python and Selenium

For those folks who are using WebDriverJS Keys.RETURN would be referenced as

webdriver.Key.RETURN

A more complete example as a reference might be helpful too:

var pressEnterToSend = function () {
    var deferred = webdriver.promise.defer();
    webdriver.findElement(webdriver.By.id('id-of-input-element')).then(function (element) {
        element.sendKeys(webdriver.Key.RETURN);
        deferred.resolve();
    });

    return deferred.promise;
};

How to auto-size an iFrame?

This is the easiest method i have found using prototype:

Main.html:

<html>
<head>


<script src="prototype.js"></script>

<script>
    function init() {
        var iframe = $(document.getElementById("iframe"));
        var iframe_content = $(iframe.contentWindow.document.getElementById("iframe_content"));
        var cy = iframe_content.getDimensions().height;
        iframe.style.height = cy + "px";
    }
</script>

</head>

<body onload="init()">


<iframe src="./content.html" id="iframe" frameBorder="0" scroll="no"></iframe>

<br>
this is the next line

</body>
</html>

content.html:

<html>
<head>
<script src="prototype.js"></script>


<style>
body {
    margin: 0px;
    padding: 0px;
}
</style>


</head>

<body>


<div id="iframe_content" style="max-height:200px;">
Sub content<br>
Sub content<br>
...
...
...
</div>


</body>
</html>

This seems to work (so far) in all the major browsers.

Troubleshooting "Illegal mix of collations" error in mysql

I had a similar problem, was trying to use the FIND_IN_SET procedure with a string variable.

SET @my_var = 'string1,string2';
SELECT * from my_table WHERE FIND_IN_SET(column_name,@my_var);

and was receiving the error

Error Code: 1267. Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation 'find_in_set'

Short answer:

No need to change any collation_YYYY variables, just add the correct collation next to your variable declaration, i.e.

SET @my_var = 'string1,string2' COLLATE utf8_unicode_ci;
SELECT * from my_table WHERE FIND_IN_SET(column_name,@my_var);

Long answer:

I first checked the collation variables:

mysql> SHOW VARIABLES LIKE 'collation%';
    +----------------------+-----------------+
    | Variable_name        | Value           |
    +----------------------+-----------------+
    | collation_connection | utf8_general_ci |
    +----------------------+-----------------+
    | collation_database   | utf8_general_ci |
    +----------------------+-----------------+
    | collation_server     | utf8_general_ci |
    +----------------------+-----------------+

Then I checked the table collation:

mysql> SHOW CREATE TABLE my_table;

CREATE TABLE `my_table` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `column_name` varchar(40) COLLATE utf8_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=125 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

This means that my variable was configured with the default collation of utf8_general_ci while my table was configured as utf8_unicode_ci.

By adding the COLLATE command next to the variable declaration, the variable collation matched the collation configured for the table.

Turning off auto indent when pasting text into vim

Although :pastetoggle or :paste and :nopaste should be working fine (if implemented - they are not always as we can see from the discussion) I highly recomment pasting using the direct approach "+p or "*p and reading with "+r or "*r:

Vim has acess to ten types of registers (:help registers) and the questioner is interested in quotestar and quoteplus from section

  1. Selection and drop registers "*, "+ and "~

Use these registers for storing and retrieving the selected text for the GUI. See quotestar and quoteplus. When the clipboard is not available or not working, the unnamed register is used instead. For Unix systems the clipboard is only available when the +xterm_clipboard feature is present. {not in Vi}

Note that there is only a distinction between "* and "+ for X11 systems.

:help x11-selection further clarifies the difference of * and +:

                                                  quoteplus quote+

There are three documented X selections: PRIMARY (which is expected to represent the current visual selection - as in Vim's Visual mode), SECONDARY (which is ill-defined) and CLIPBOARD (which is expected to be used for cut, copy and paste operations).

Of these three, Vim uses PRIMARY when reading and writing the "* register (hence when the X11 selections are available, Vim sets a default value for 'clipboard' of "autoselect"), and CLIPBOARD when reading and writing the "+ register. Vim does not access the SECONDARY selection.

Examples: (assuming the default option values)

  • Select an URL in Visual mode in Vim. Go to your browser and click the middle mouse button in the URL text field. The selected text will be inserted (hopefully!). Note: in Firefox you can set the middlemouse.contentLoadURL preference to true in about:config, then the selected URL will be used when pressing middle mouse button in most places in the window.

  • Select some text in your browser by dragging with the mouse. Go to Vim and press the middle mouse button: The selected text is inserted.

  • Select some text in Vim and do "+y. Go to your browser, select some text in a textfield by dragging with the mouse. Now use the right mouse button and select "Paste" from the popup menu. The selected text is overwritten by the text from Vim. Note that the text in the "+ register remains available when making a Visual selection, which makes other text available in the "* register. That allows overwriting selected text.

Save base64 string as PDF at client side with JavaScript

you can use this function to download file from base64.

function downloadPDF(pdf) {
const linkSource = `data:application/pdf;base64,${pdf}`;
const downloadLink = document.createElement("a");
const fileName = "abc.pdf";
downloadLink.href = linkSource;
downloadLink.download = fileName;
downloadLink.click();}

This code will made an anchor tag with href and download file. if you want to use button then you can call click method on your button click.

i hope this will help of you thanks

SQL Server Jobs with SSIS packages - Failed to decrypt protected XML node "DTS:Password" with error 0x8009000B

It is because creator of the SSIS packages is someone else and other person is executing the packages.

If suppose A person has created SSIS packages and B person is trying to execute than the above error comes.

You can solve the error by changing creator name from package properties from A to B.

Thanks, Kiran Sagar

How to set null to a GUID property

I think this is the correct way:

Guid filed = Guid.Empty;

Sorting list based on values from another list

list1 = ['a','b','c','d','e','f','g','h','i']
list2 = [0,1,1,0,1,2,2,0,1]

output=[]
cur_loclist = []

To get unique values present in list2

list_set = set(list2)

To find the loc of the index in list2

list_str = ''.join(str(s) for s in list2)

Location of index in list2 is tracked using cur_loclist

[0, 3, 7, 1, 2, 4, 8, 5, 6]

for i in list_set:
cur_loc = list_str.find(str(i))

while cur_loc >= 0:
    cur_loclist.append(cur_loc)
    cur_loc = list_str.find(str(i),cur_loc+1)

print(cur_loclist)

for i in range(0,len(cur_loclist)):
output.append(list1[cur_loclist[i]])
print(output)

how to add css class to html generic control div?

if you want to add a class to an existing list of classes for an element:

element.Attributes.Add("class", element.Attributes["class"] + " " + sType);

Sql Server return the value of identity column after insert statement

SELECT SCOPE_IDENTITY()

after the insert statement

Please refer the following links

http://msdn.microsoft.com/en-us/library/ms190315.aspx

check if file exists in php

file_exists checks whether a file exist in the specified path or not.

Syntax:

file_exists ( string $filename )

Returns TRUE if the file or directory specified by filename exists; FALSE otherwise.

$filename = BASE_DIR."images/a/test.jpg";
if (file_exists($filename)){
    echo "File exist.";
}else{
    echo "File does not exist.";
}

Another alternative method you can use getimagesize(), it will return 0(zero) if file/directory is not available in the specified path.

if (@getimagesize($filename)) {...}

Make footer stick to bottom of page correctly

A simple solution that i use, works from IE8+

Give min-height:100% on html so that if content is less then still page takes full view-port height and footer sticks at bottom of page. When content increases the footer shifts down with content and keep sticking to bottom.

JS fiddle working Demo: http://jsfiddle.net/3L3h64qo/2/

Css

html{
  position:relative; 
  min-height: 100%;
}
/*Normalize html and body elements,this style is just good to have*/
html,body{
  margin:0;
  padding:0;
}
.pageContentWrapper{
  margin-bottom:100px;/* Height of footer*/
} 
.footer{
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height:100px;
    background:#ccc;
}

Html

   <html>
    <body>
        <div class="pageContentWrapper">
            <!-- All the page content goes here-->
        </div>
        <div class="footer">
        </div>
    </body>
    </html>

Maven Could not resolve dependencies, artifacts could not be resolved

Have come across such issue. The root cause is the .m2 folder. You gotta make sure that whatever you're trying to access is present there in your .m2 folder (this is your local repo). If the stuff is there then you're good. This is usually present inside of users folder on your system (be it mac/linux or even windows)

How can I check if a View exists in a Database?

IN SQL Server ,

declare @ViewName nvarchar(20)='ViewNameExample'

if exists(SELECT 1 from sys.objects where object_Id=object_Id(@ViewName) and Type_Desc='VIEW')
begin
    -- Your SQL Code goes here ...

end

Add alternating row color to SQL Server Reporting services report

When using row and column groups both, I had an issue where the colors would alternate between the columns even though it was the same row. I resolved this by using a global variable that alternates only when the row changes:

Public Dim BGColor As String = "#ffffff"

Function AlternateColor() As String
  If BGColor = "#cccccc" Then
    BGColor = "#ffffff"
    Return "#cccccc"
  Else
    BGColor = "#cccccc"
    Return "#ffffff"
  End  If
End Function

Now, in the first column of the row you want to alternate, set the color expression to:

=Code.AlternateColor()

-

In the remaining columns, set them all to:

=Code.BGColor

This should make the colors alternate only after the first column is drawn.

This may (unverifiably) improve performance, too, since it does not need to do a math computation for each column.

What are all the differences between src and data-src attributes?

Well the data src attribute is just used for binding data for example ASP.NET ...

W3School src attribute

MSDN datasrc attribute

How to get the next auto-increment id in mysql

use "mysql_insert_id()". mysql_insert_id() acts on the last performed query, be sure to call mysql_insert_id() immediately after the query that generates the value.

Below are the example of use:

<?php
    $link = mysql_connect('localhost', 'username', 'password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
mysql_select_db('mydb');

mysql_query("INSERT INTO mytable  VALUES('','value')");
printf("Last inserted record has id %d\n", mysql_insert_id());
    ?>

I hope above example is useful.

How to keep form values after post

you can save them into a $_SESSION variable and then when the user calls that page again populate all the inputs with their respective session variables.

I want to multiply two columns in a pandas DataFrame and add the result into a new column

If we're willing to sacrifice the succinctness of Hayden's solution, one could also do something like this:

In [22]: orders_df['C'] = orders_df.Action.apply(
               lambda x: (1 if x == 'Sell' else -1))

In [23]: orders_df   # New column C represents the sign of the transaction
Out[23]:
   Prices  Amount Action  C
0       3      57   Sell  1
1      89      42   Sell  1
2      45      70    Buy -1
3       6      43   Sell  1
4      60      47   Sell  1
5      19      16    Buy -1
6      56      89   Sell  1
7       3      28    Buy -1
8      56      69   Sell  1
9      90      49    Buy -1

Now we have eliminated the need for the if statement. Using DataFrame.apply(), we also do away with the for loop. As Hayden noted, vectorized operations are always faster.

In [24]: orders_df['Value'] = orders_df.Prices * orders_df.Amount * orders_df.C

In [25]: orders_df   # The resulting dataframe
Out[25]:
   Prices  Amount Action  C  Value
0       3      57   Sell  1    171
1      89      42   Sell  1   3738
2      45      70    Buy -1  -3150
3       6      43   Sell  1    258
4      60      47   Sell  1   2820
5      19      16    Buy -1   -304
6      56      89   Sell  1   4984
7       3      28    Buy -1    -84
8      56      69   Sell  1   3864
9      90      49    Buy -1  -4410

This solution takes two lines of code instead of one, but is a bit easier to read. I suspect that the computational costs are similar as well.

What does '?' do in C++?

This is commonly referred to as the conditional operator, and when used like this:

condition ? result_if_true : result_if_false

... if the condition evaluates to true, the expression evaluates to result_if_true, otherwise it evaluates to result_if_false.

It is syntactic sugar, and in this case, it can be replaced with

int qempty()
{ 
  if(f == r)
  {
      return 1;
  } 
  else 
  {
      return 0;
  }
}

Note: Some people refer to ?: it as "the ternary operator", because it is the only ternary operator (i.e. operator that takes three arguments) in the language they are using.

Post values from a multiple select

try this : here select is your select element

let select = document.getElementsByClassName('lstSelected')[0],
    options = select.options,
    len = options.length,
    data='',
    i=0;
while (i<len){
    if (options[i].selected)
        data+= "&" + select.name + '=' + options[i].value;
    i++;
}
return data;

Data is in the form of query string i.e.name=value&name=anotherValue

How to get the directory of the currently running file?

This should do it:

import (
    "fmt"
    "log"
    "os"
    "path/filepath"
)

func main() {
    dir, err := filepath.Abs(filepath.Dir(os.Args[0]))
    if err != nil {
            log.Fatal(err)
    }
    fmt.Println(dir)
}

What's the difference between MyISAM and InnoDB?

The main differences between InnoDB and MyISAM ("with respect to designing a table or database" you asked about) are support for "referential integrity" and "transactions".

If you need the database to enforce foreign key constraints, or you need the database to support transactions (i.e. changes made by two or more DML operations handled as single unit of work, with all of the changes either applied, or all the changes reverted) then you would choose the InnoDB engine, since these features are absent from the MyISAM engine.

Those are the two biggest differences. Another big difference is concurrency. With MyISAM, a DML statement will obtain an exclusive lock on the table, and while that lock is held, no other session can perform a SELECT or a DML operation on the table.

Those two specific engines you asked about (InnoDB and MyISAM) have different design goals. MySQL also has other storage engines, with their own design goals.

So, in choosing between InnoDB and MyISAM, the first step is in determining if you need the features provided by InnoDB. If not, then MyISAM is up for consideration.

A more detailed discussion of differences is rather impractical (in this forum) absent a more detailed discussion of the problem space... how the application will use the database, how many tables, size of the tables, the transaction load, volumes of select, insert, updates, concurrency requirements, replication features, etc.


The logical design of the database should be centered around data analysis and user requirements; the choice to use a relational database would come later, and even later would the choice of MySQL as a relational database management system, and then the selection of a storage engine for each table.

How do I reverse an int array in Java?

Solution with o(n) time complexity and o(1) space complexity.

void reverse(int[] array) {
    int start = 0;
    int end = array.length - 1;
    while (start < end) {
        int temp = array[start];
        array[start] = array[end];
        array[end] = temp;
        start++;
        end--;
    }
}

Better/Faster to Loop through set or list?

I the list is vary large looping two time over it will take a lot of time and more in the second time you are looping a set not a list and as we know iterating over a set is slower than list.

i think you need the power of generator and set.

def first_test():

    def loop_one_time(my_list):
        # create a set to keep the items.
        iterated_items = set()
        # as we know iterating over list is faster then list.
        for value in my_list: 
            # as we know checking if element exist in set is very fast not
            # metter the size of the set.
            if value not in iterated_items:  
                iterated_items.add(value) # add this item to list
                yield value


    mylist = [3,1,5,2,4,4,1,4,2,5,1,3]

    for v in loop_one_time(mylist):pass



def second_test():
    mylist = [3,1,5,2,4,4,1,4,2,5,1,3]
    s = set(mylist)
    for v in s:pass


import timeit

print(timeit.timeit('first_test()', setup='from __main__ import first_test', number=10000))
print(timeit.timeit('second_test()', setup='from __main__ import second_test', number=10000))

out put:

   0.024003583388435043
   0.010424674188938422

Note: this technique order is guaranteed

How can I rename a field for all documents in MongoDB?

If you are using MongoMapper, this works:

Access.collection.update( {}, { '$rename' => { 'location' => 'location_info' } }, :multi => true )

Comparing two java.util.Dates to see if they are in the same day

private boolean isSameDay(Date date1, Date date2) {
        Calendar calendar1 = Calendar.getInstance();
        calendar1.setTime(date1);
        Calendar calendar2 = Calendar.getInstance();
        calendar2.setTime(date2);
        boolean sameYear = calendar1.get(Calendar.YEAR) == calendar2.get(Calendar.YEAR);
        boolean sameMonth = calendar1.get(Calendar.MONTH) == calendar2.get(Calendar.MONTH);
        boolean sameDay = calendar1.get(Calendar.DAY_OF_MONTH) == calendar2.get(Calendar.DAY_OF_MONTH);
        return (sameDay && sameMonth && sameYear);
    }

How to completely remove node.js from Windows

I came here because the Remove button was not available from Add/Remove programs. It was saying "Node.js cannot be removed".

This worked:

  1. Got the .msi of my installed Node version. Ran it to repair the installation just in case.
  2. Opened the Administrator command prompt and ran msiexec /uninstall <node.msi>.

How to insert text into the textarea at the current cursor position?

I like simple javascript, and I usually have jQuery around. Here's what I came up with, based off mparkuk's:

function typeInTextarea(el, newText) {
  var start = el.prop("selectionStart")
  var end = el.prop("selectionEnd")
  var text = el.val()
  var before = text.substring(0, start)
  var after  = text.substring(end, text.length)
  el.val(before + newText + after)
  el[0].selectionStart = el[0].selectionEnd = start + newText.length
  el.focus()
}

$("button").on("click", function() {
  typeInTextarea($("textarea"), "some text")
  return false
})

Here's a demo: http://codepen.io/erikpukinskis/pen/EjaaMY?editors=101

How to convert the following json string to java object?

Gson is also good for it: http://code.google.com/p/google-gson/

" Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of. "

Check the API examples: https://sites.google.com/site/gson/gson-user-guide#TOC-Overview More examples: http://www.mkyong.com/java/how-do-convert-java-object-to-from-json-format-gson-api/

Why is using a wild card with a Java import statement bad?

It's not bad to use a wild card with a Java import statement.

In Clean Code, Robert C. Martin actually recommends using them to avoid long import lists.

Here is the recommendation:

J1: Avoid Long Import Lists by Using Wildcards

If you use two or more classes from a package, then import the whole package with

import package.*;

Long lists of imports are daunting to the reader. We don’t want to clutter up the tops of our modules with 80 lines of imports. Rather we want the imports to be a concise statement about which packages we collaborate with.

Specific imports are hard dependencies, whereas wildcard imports are not. If you specifically import a class, then that class must exist. But if you import a package with a wildcard, no particular classes need to exist. The import statement simply adds the package to the search path when hunting for names. So no true dependency is created by such imports, and they therefore serve to keep our modules less coupled.

There are times when the long list of specific imports can be useful. For example, if you are dealing with legacy code and you want to find out what classes you need to build mocks and stubs for, you can walk down the list of specific imports to find out the true qualified names of all those classes and then put the appropriate stubs in place. However, this use for specific imports is very rare. Furthermore, most modern IDEs will allow you to convert the wildcarded imports to a list of specific imports with a single command. So even in the legacy case it’s better to import wildcards.

Wildcard imports can sometimes cause name conflicts and ambiguities. Two classes with the same name, but in different packages, will need to be specifically imported, or at least specifically qualified when used. This can be a nuisance but is rare enough that using wildcard imports is still generally better than specific imports.

How do I create the small icon next to the website tab for my site?

It is called favicon.ico and you can generate it from this site.

http://www.favicon.cc/

What is the difference between & vs @ and = in angularJS

@: one-way binding

=: two-way binding

&: function binding

Properly embedding Youtube video into bootstrap 3.0 page

I know it's late, I have the same issue with an old custom theme, just added to boostrap.css:

.embed-responsive {
  position: relative;
  display: block;
  height: 0;
  padding: 0;
  overflow: hidden;
}
.embed-responsive .embed-responsive-item,
.embed-responsive iframe,
.embed-responsive embed,
.embed-responsive object,
.embed-responsive video {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}
.embed-responsive-16by9 {
  padding-bottom: 56.25%;
}
.embed-responsive-4by3 {
  padding-bottom: 75%;
}

And for the video:

<div class="embed-responsive embed-responsive-16by9" >
<iframe class="embed-responsive-item"  src="https://www.youtube.com/embed/jVIxe3YLNs8"></iframe>
</div>

How do I get Flask to run on port 80?

set the port with app.run(port=80,debug=True) you should set debug to true when on dev

Angular 2: How to write a for loop, not a foreach loop

   queNumMin = 23;
   queNumMax= 26;
   result = 0;
for (let index = this.queNumMin; index <= this.queNumMax; index++) {
         this.result = index
         console.log( this.result);
     }

Range min and max number

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

You can stop banging your heads now. Here is the wrapper for the member function to support existing functions taking in plain C functions as arguments. thread_local directive is the key here.

http://cpp.sh/9jhk3

// Example program
#include <iostream>
#include <string>

using namespace std;

typedef int FooCooker_ (int);

// Existing function
extern "C" void cook_10_foo (FooCooker_ FooCooker) {
    cout << "Cooking 10 Foo ..." << endl;
    cout << "FooCooker:" << endl;
    FooCooker (10);
}

struct Bar_ {
    Bar_ (int Foo = 0) : Foo (Foo) {};
    int cook (int Foo) {
        cout << "This Bar got " << this->Foo << endl;
        if (this->Foo >= Foo) {
            this->Foo -= Foo;
            cout << Foo << " cooked" << endl;
            return Foo;
        } else {
            cout << "Can't cook " <<  Foo << endl;
            return 0;
        }
    }
    int Foo = 0;
};

// Each Bar_ object and a member function need to define
// their own wrapper with a global thread_local object ptr
// to be called as a plain C function.
thread_local static Bar_* BarPtr = NULL;
static int cook_in_Bar (int Foo) {
    return BarPtr->cook (Foo);
}

thread_local static Bar_* Bar2Ptr = NULL;
static int cook_in_Bar2 (int Foo) {
    return Bar2Ptr->cook (Foo);
}

int main () {
  BarPtr = new Bar_ (20);
  cook_10_foo (cook_in_Bar);

  Bar2Ptr = new Bar_ (40);
  cook_10_foo (cook_in_Bar2);

  delete BarPtr;
  delete Bar2Ptr;
  return 0;
}

Please comment on any issues with this approach.

Other answers fail to call existing plain C functions: http://cpp.sh/8exun

Failed to create provisioning profile

Change Deployment Target to newer version and then solved

Make an html number input always display 2 decimal places

an inline solution combines Groot and Ivaylo suggestions in the format below:

onchange="(function(el){el.value=parseFloat(el.value).toFixed(2);})(this)"

position fixed header in html

Your #container should be outside of the #header-wrap, then specify a fixed height for #header-wrap, after, specify margin-top for #container equal to the #header-wrap's height. Something like this:

#header-wrap {
    position: fixed;
    height: 200px;
    top: 0;
    width: 100%;
    z-index: 100;
}
#container{ 
    margin-top: 200px;
}

Hope this is what you need: http://jsfiddle.net/KTgrS/

Java executors: how to be notified, without blocking, when a task completes?

Define a callback interface to receive whatever parameters you want to pass along in the completion notification. Then invoke it at the end of the task.

You could even write a general wrapper for Runnable tasks, and submit these to ExecutorService. Or, see below for a mechanism built into Java 8.

class CallbackTask implements Runnable {

  private final Runnable task;

  private final Callback callback;

  CallbackTask(Runnable task, Callback callback) {
    this.task = task;
    this.callback = callback;
  }

  public void run() {
    task.run();
    callback.complete();
  }

}

With CompletableFuture, Java 8 included a more elaborate means to compose pipelines where processes can be completed asynchronously and conditionally. Here's a contrived but complete example of notification.

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;

public class GetTaskNotificationWithoutBlocking {

  public static void main(String... argv) throws Exception {
    ExampleService svc = new ExampleService();
    GetTaskNotificationWithoutBlocking listener = new GetTaskNotificationWithoutBlocking();
    CompletableFuture<String> f = CompletableFuture.supplyAsync(svc::work);
    f.thenAccept(listener::notify);
    System.out.println("Exiting main()");
  }

  void notify(String msg) {
    System.out.println("Received message: " + msg);
  }

}

class ExampleService {

  String work() {
    sleep(7000, TimeUnit.MILLISECONDS); /* Pretend to be busy... */
    char[] str = new char[5];
    ThreadLocalRandom current = ThreadLocalRandom.current();
    for (int idx = 0; idx < str.length; ++idx)
      str[idx] = (char) ('A' + current.nextInt(26));
    String msg = new String(str);
    System.out.println("Generated message: " + msg);
    return msg;
  }

  public static void sleep(long average, TimeUnit unit) {
    String name = Thread.currentThread().getName();
    long timeout = Math.min(exponential(average), Math.multiplyExact(10, average));
    System.out.printf("%s sleeping %d %s...%n", name, timeout, unit);
    try {
      unit.sleep(timeout);
      System.out.println(name + " awoke.");
    } catch (InterruptedException abort) {
      Thread.currentThread().interrupt();
      System.out.println(name + " interrupted.");
    }
  }

  public static long exponential(long avg) {
    return (long) (avg * -Math.log(1 - ThreadLocalRandom.current().nextDouble()));
  }

}

Using R to download zipped data file, extract, and import data

rio() would be very suitable for this - it uses the file extension of a file name to determine what kind of file it is, so it will work with a large variety of file types. I've also used unzip() to list the file names within the zip file, so its not necessary to specify the file name(s) manually.

library(rio)

# create a temporary directory
td <- tempdir()

# create a temporary file
tf <- tempfile(tmpdir=td, fileext=".zip")

# download file from internet into temporary location
download.file("http://download.companieshouse.gov.uk/BasicCompanyData-part1.zip", tf)

# list zip archive
file_names <- unzip(tf, list=TRUE)

# extract files from zip file
unzip(tf, exdir=td, overwrite=TRUE)

# use when zip file has only one file
data <- import(file.path(td, file_names$Name[1]))

# use when zip file has multiple files
data_multiple <- lapply(file_names$Name, function(x) import(file.path(td, x)))

# delete the files and directories
unlink(td)

Javascript: output current datetime in YYYY/mm/dd hh:m:sec format

I wrote a simple library for manipulating the JavaScript date object. You can try this:

var dateString = timeSolver.getString(new Date(), "YYYY/MM/DD HH:MM:SS.SSS")

Library here: https://github.com/sean1093/timeSolver

How to set a timer in android

I used to use (Timer, TimerTask) as well as Handler to kick off (time-consuming) tasks periodically. Now I've switched the whole to RxJava. RxJava provides Observable.timer which is simpler, less error-prone, hassle-free to use.

public class BetterTimerFragment extends Fragment {
  public static final String TAG = "BetterTimer";
  private TextView timeView;
  private Subscription timerSubscription;

  @Override
  public View onCreateView(LayoutInflater inflater,
                           @Nullable ViewGroup container,
                           @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_timer, container, false);
  }

  @Override
  public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    timeView = (TextView) view.findViewById(R.id.timeView);
  }

  @Override
  public void onResume() {
    super.onResume();

    // Right after the app is visible to users, delay 2 seconds
    // then kick off a (heavy) task every 10 seconds.
    timerSubscription = Observable.timer(2, 10, TimeUnit.SECONDS)
        .map(new Func1<Long, String>() {
          @Override
          public String call(Long unused) {
            // TODO: Probably do time-consuming work here.
            // This runs on a different thread than the main thread.
            return "Time: " + System.currentTimeMillis();
          }
        })
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Action1<String>() {
          @Override
          public void call(String timeText) {
            // The result will then be propagated back to the main thread.
            timeView.setText(timeText);
          }
        }, new Action1<Throwable>() {
          @Override
          public void call(Throwable throwable) {
            Log.e(TAG, throwable.getMessage(), throwable);
          }
        });
  }

  @Override
  public void onPause() {
    super.onPause();

    // Don't kick off tasks when the app gets invisible.
    timerSubscription.unsubscribe();
  }
}

Amazon Linux: apt-get: command not found

This is one of the command which you can run to install apt-get:

wget http://security.ubuntu.com/ubuntu/pool/main/a/apt/apt_1.4_amd64.deb

How to execute powershell commands from a batch file?

Type in cmd.exe Powershell -Help and see the examples.

How to delete a folder and all contents using a bat file in windows?

  1. del /s /q c:\where ever the file is\*
  2. rmdir /s /q c:\where ever the file is\
  3. mkdir c:\where ever the file is\

How to use callback with useState hook in react

you can utilize useCallback hook to do this.

function Parent() {
  const [name, setName] = useState("");
  const getChildChange = useCallback( (updatedName) => {
    setName(updatedName);
  }, []);

  return <div> {name} :
    <Child getChildChange={getChildChange} ></Child>
  </div>
}

function Child(props) {
  const [name, setName] = useState("");

  function handleChange(ele) {
    setName(ele.target.value);
    props.getChildChange(ele.target.value);
  }

  function collectState() {
    return name;
  }

  return (<div>
    <input onChange={handleChange} value={name}></input>
  </div>);
}

Android Support Design TabLayout: Gravity Center and Mode Scrollable

Tab gravity only effects MODE_FIXED.

One possible solution is to set your layout_width to wrap_content and layout_gravity to center_horizontal:

<android.support.design.widget.TabLayout
    android:id="@+id/sliding_tabs"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    app:tabMode="scrollable" />

If the tabs are smaller than the screen width, the TabLayout itself will also be smaller and it will be centered because of the gravity. If the tabs are bigger than the screen width, the TabLayout will match the screen width and scrolling will activate.

How can I get a side-by-side diff when I do "git diff"?

export GIT_EXTERNAL_DIFF='meld $2 $5; echo >/dev/null'

then simply:

git diff

How do I navigate to another page when PHP script is done?

if ($done)
{
    header("Location: /url/to/the/other/page");
    exit;
}

Using reflection in Java to create a new instance with the reference variable type set to the new instance class name?

This line seems to sum up the crux of your problem:

The issue with this is that now you can't call any new methods (only overrides) on the implementing class, as your object reference variable has the interface type.

You are pretty stuck in your current implementation, as not only do you have to attempt a cast, you also need the definition of the method(s) that you want to call on this subclass. I see two options:

1. As stated elsewhere, you cannot use the String representation of the Class name to cast your reflected instance to a known type. You can, however, use a String equals() test to determine whether your class is of the type that you want, and then perform a hard-coded cast:

try {
   String className = "com.path.to.ImplementationType";// really passed in from config
   Class c = Class.forName(className);
   InterfaceType interfaceType = (InterfaceType)c.newInstance();
   if (className.equals("com.path.to.ImplementationType") {
      ((ImplementationType)interfaceType).doSomethingOnlyICanDo();
   } 
} catch (Exception e) {
   e.printStackTrace();
}

This looks pretty ugly, and it ruins the nice config-driven process that you have. I dont suggest you do this, it is just an example.

2. Another option you have is to extend your reflection from just Class/Object creation to include Method reflection. If you can create the Class from a String passed in from a config file, you can also pass in a method name from that config file and, via reflection, get an instance of the Method itself from your Class object. You can then call invoke(http://java.sun.com/javase/6/docs/api/java/lang/reflect/Method.html#invoke(java.lang.Object, java.lang.Object...)) on the Method, passing in the instance of your class that you created. I think this will help you get what you are after.

Here is some code to serve as an example. Note that I have taken the liberty of hard coding the params for the methods. You could specify them in a config as well, and would need to reflect on their class names to define their Class obejcts and instances.

public class Foo {

    public void printAMessage() {
    System.out.println(toString()+":a message");
    }
    public void printAnotherMessage(String theString) {
        System.out.println(toString()+":another message:" + theString);
    }

    public static void main(String[] args) {
        Class c = null;
        try {
            c = Class.forName("Foo");
            Method method1 = c.getDeclaredMethod("printAMessage", new Class[]{});
            Method method2 = c.getDeclaredMethod("printAnotherMessage", new Class[]{String.class});
            Object o = c.newInstance();
            System.out.println("this is my instance:" + o.toString());
            method1.invoke(o);
            method2.invoke(o, "this is my message, from a config file, of course");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException nsme){
            nsme.printStackTrace();
        } catch (IllegalAccessException iae) {
            iae.printStackTrace();
        } catch (InstantiationException ie) {
            ie.printStackTrace();
        } catch (InvocationTargetException ite) {
            ite.printStackTrace();
        }
    }
}

and my output:

this is my instance:Foo@e0cf70
Foo@e0cf70:a message
Foo@e0cf70:another message:this is my message, from a config file, of course

python exception message capturing

Updating this to something simpler for logger (works for both python 2 and 3). You do not need traceback module.

import logging

logger = logging.Logger('catch_all')

def catchEverythingInLog():
    try:
        ... do something ...
    except Exception as e:
        logger.error(e, exc_info=True)
        ... exception handling ...

This is now the old way (though still works):

import sys, traceback

def catchEverything():
    try:
        ... some operation(s) ...
    except:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        ... exception handling ...

exc_value is the error message.

Which characters make a URL invalid?

I need to select character to split urls in string, so I decided to create list of characters which could not be found in URL by myself:

>>> allowed = "-_.~!*'();:@&=+$,/?%#[]?@ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
>>> from string import printable
>>> ''.join(set(printable).difference(set(allowed)))
'`" <\x0b\n\r\x0c\\\t{^}|>'

So, the possible choices are the newline, tab, space, backslash and "<>{}^|. I guess I'll go with the space or newline. :)

How to make a copy of an object in C#

You can use MemberwiseClone

obj myobj2 = (obj)myobj.MemberwiseClone();

The copy is a shallow copy which means the reference properties in the clone are pointing to the same values as the original object but that shouldn't be an issue in your case as the properties in obj are of value types.

If you own the source code, you can also implement ICloneable

JavaScript "cannot read property "bar" of undefined

Just check for it before you pass to your function. So you would pass:

thing.foo ? thing.foo.bar : undefined

Which Ruby version am I really running?

If you have access to a console in the context you are investigating, you can determine which version you are running by printing the value of the global constant RUBY_VERSION.

How to sort a List<Object> alphabetically using Object name field

This is assuming a list of YourClass instead of Object, as explained by amit.

You can use this bit from the Google Guava library:

Collections.sort(list, Ordering.natural()
  .onResultOf(new Function<String,YourClass>() {
  public String call(YourClass o) {
     return o.getName();
  }))
  .nullsLast();

The other answers which mention Comparator are not incorrect, since Ordering implements Comparator. This solution is, in my opinion, a little easier, though it may be harder if you're a beginner and not used to using libraries and/or "functional programming".

Copied shamelessly from this answer on my own question.

how to check redis instance version?

$ redis-server --version

gives you the version.

How to use ES6 Fat Arrow to .filter() an array of objects

It appears I cannot use an if statement.

Arrow functions either allow to use an expression or a block as their body. Passing an expression

foo => bar

is equivalent to the following block

foo => { return bar; }

However,

if (person.age > 18) person

is not an expression, if is a statement. Hence you would have to use a block, if you wanted to use if in an arrow function:

foo => {  if (person.age > 18) return person; }

While that technically solves the problem, this a confusing use of .filter, because it suggests that you have to return the value that should be contained in the output array. However, the callback passed to .filter should return a Boolean, i.e. true or false, indicating whether the element should be included in the new array or not.

So all you need is

family.filter(person => person.age > 18);

In ES5:

family.filter(function (person) {
  return person.age > 18;
});

Creating a procedure in mySql with parameters

(IN @brugernavn varchar(64)**)**,IN @password varchar(64))

The problem is the )

number several equations with only one number

First of all, you probably don't want the align environment if you have only one column of equations. In fact, your example is probably best with the cases environment. But to answer your question directly, used the aligned environment within equation - this way the outside environment gives the number:

\begin{equation}
  \begin{aligned}
  w^T x_i + b &\geq 1-\xi_i &\text{ if }& y_i=1,  \\
  w^T x_i + b &\leq -1+\xi_i & \text{ if } &y_i=-1,
  \end{aligned}
\end{equation}

The documentation of the amsmath package explains this and more.

Is it possible to define more than one function per file in MATLAB, and access them from outside that file?

You could also group functions in one main file together with the main function looking like this:

function [varargout] = main( subfun, varargin )
[varargout{1:nargout}] = feval( subfun, varargin{:} ); 

% paste your subfunctions below ....
function str=subfun1
str='hello'

Then calling subfun1 would look like this: str=main('subfun1')

How do I get the size of a java.sql.ResultSet?

The way of getting size of ResultSet, No need of using ArrayList etc

int size =0;  
if (rs != null)   
{  
rs.beforeFirst();  
 rs.last();  
size = rs.getRow();
}

Now You will get size, And if you want print the ResultSet, before printing use following line of code too,

rs.beforeFirst();  

How to query GROUP BY Month in a Year

I am doing like this in MSSQL

Getting Monthly Data:

 SELECT YEAR(DATE_CREATED) [Year], MONTH(DATE_CREATED) [Month], 
     DATENAME(MONTH,DATE_CREATED) [Month Name], SUM(Num_of_Pictures) [Pictures Count]
    FROM pictures_table
    GROUP BY YEAR(DATE_CREATED), MONTH(DATE_CREATED), 
     DATENAME(MONTH, DATE_CREATED)
    ORDER BY 1,2

Getting Monthly Data using PIVOT:

SELECT *
FROM (SELECT YEAR(DATE_CREATED) [Year], 
       DATENAME(MONTH, DATE_CREATED) [Month], 
       SUM(Num_of_Pictures) [Pictures Count]
      FROM pictures_table
      GROUP BY YEAR(DATE_CREATED), 
      DATENAME(MONTH, DATE_CREATED)) AS MontlySalesData
PIVOT( SUM([Pictures Count])   
    FOR Month IN ([January],[February],[March],[April],[May],
    [June],[July],[August],[September],[October],[November],
    [December])) AS MNamePivot

How to properly express JPQL "join fetch" with "where" clause as JPA 2 CriteriaQuery?

In JPQL the same is actually true in the spec. The JPA spec does not allow an alias to be given to a fetch join. The issue is that you can easily shoot yourself in the foot with this by restricting the context of the join fetch. It is safer to join twice.

This is normally more an issue with ToMany than ToOnes. For example,

Select e from Employee e 
join fetch e.phones p 
where p.areaCode = '613'

This will incorrectly return all Employees that contain numbers in the '613' area code but will left out phone numbers of other areas in the returned list. This means that an employee that had a phone in the 613 and 416 area codes will loose the 416 phone number, so the object will be corrupted.

Granted, if you know what you are doing, the extra join is not desirable, some JPA providers may allow aliasing the join fetch, and may allow casting the Criteria Fetch to a Join.

Automatically start forever (node) on system restart

I tried lots of the above answers. None of them worked for me. My app is installed in /home and as user, not as root. This probably means that when the above mentioned start scripts run, /home is not mounted yet, so the app is not started.

Then I found these instructions by Digital Ocean:

https://www.digitalocean.com/community/tutorials/how-to-use-pm2-to-setup-a-node-js-production-environment-on-an-ubuntu-vps

Using PM2 as explained was very simple and works perfectly: My virtual servers had two physical crashes since - downtime was only about a minute.

ReactJS: Warning: setState(...): Cannot update during an existing state transition

The solution that I use to open Popover for components is reactstrap (React Bootstrap 4 components).

    class Settings extends Component {
        constructor(props) {
            super(props);

            this.state = {
              popoversOpen: [] // array open popovers
            }
        }

        // toggle my popovers
        togglePopoverHelp = (selected) => (e) => {
            const index = this.state.popoversOpen.indexOf(selected);
            if (index < 0) {
              this.state.popoversOpen.push(selected);
            } else {
              this.state.popoversOpen.splice(index, 1);
            }
            this.setState({ popoversOpen: [...this.state.popoversOpen] });
        }

        render() {
            <div id="settings">
                <button id="PopoverTimer" onClick={this.togglePopoverHelp(1)} className="btn btn-outline-danger" type="button">?</button>
                <Popover placement="left" isOpen={this.state.popoversOpen.includes(1)} target="PopoverTimer" toggle={this.togglePopoverHelp(1)}>
                  <PopoverHeader>Header popover</PopoverHeader>
                  <PopoverBody>Description popover</PopoverBody>
                </Popover>

                <button id="popoverRefresh" onClick={this.togglePopoverHelp(2)} className="btn btn-outline-danger" type="button">?</button>
                <Popover placement="left" isOpen={this.state.popoversOpen.includes(2)} target="popoverRefresh" toggle={this.togglePopoverHelp(2)}>
                  <PopoverHeader>Header popover 2</PopoverHeader>
                  <PopoverBody>Description popover2</PopoverBody>
                </Popover>
            </div>
        }
    }

MySQL: Error Code: 1118 Row size too large (> 8126). Changing some columns to TEXT or BLOB

I recently created a table with 82 columns and had the same error with InnoDB. To bypass the problem we switched the table format to MyISAM as it was just used for a basic form.

Abort a git cherry-pick?

You can do the following

git cherry-pick --abort

From the git cherry-pick docs

--abort  

Cancel the operation and return to the pre-sequence state.

How do you set up use HttpOnly cookies in PHP

<?php
//None HttpOnly cookie:
setcookie("abc", "test", NULL, NULL, NULL, NULL, FALSE); 

//HttpOnly cookie:
setcookie("abc", "test", NULL, NULL, NULL, NULL, TRUE); 

?>

Source

Delete last N characters from field in a SQL Server database

I got the answer to my own question, ant this is:

select reverse(stuff(reverse('a,b,c,d,'), 1, N, ''))

Where N is the number of characters to remove. This avoids to write the complex column/string twice

Android : Capturing HTTP Requests with non-rooted android device

There is many ways to do that but one of them is fiddler

Fiddler Configuration

  1. Go to options
  2. In HTTPS tab, enable Capture HTTPS Connects and Decrypt HTTPS traffic
  3. In Connections tab, enable Allow remote computers to connect
  4. Restart fiddler

Android Configuration

  1. Connect to same network
  2. Modify network settings
  3. Add proxy for connection with your PC's IP address ( or hostname ) and default fiddler's port ( 8888 / you can change that in settings )

Now you can see full log from your device in fiddler

Also you can find a full instruction here

How to make padding:auto work in CSS?

You can reset the padding (and I think everything else) with initial to the default.

p {
    padding: initial;
}

What is the Regular Expression For "Not Whitespace and Not a hyphen"

In Java:

    String regex = "[^-\\s]";

    System.out.println("-".matches(regex)); // prints "false"
    System.out.println(" ".matches(regex)); // prints "false"
    System.out.println("+".matches(regex)); // prints "true"

The regex [^-\s] works as expected. [^\s-] also works.

See also

WRONGTYPE Operation against a key holding the wrong kind of value php

I faced this issue when trying to set something to redis. The problem was that I previously used "set" method to set data with a certain key, like

$redis->set('persons', $persons)

Later I decided to change to "hSet" method, and I tried it this way

foreach($persons as $person){
    $redis->hSet('persons', $person->id, $person);
}

Then I got the aforementioned error. So, what I had to do is to go to redis-cli and manually delete "persons" entry with

del persons

It simply couldn't write different data structure under existing key, so I had to delete the entry and hSet then.

Maven error: Could not find or load main class org.codehaus.plexus.classworlds.launcher.Launcher

The solution for later versions of Maven is straight-forward. I am on OS X ElCap, 10.11.6 and upgraded to Maven 3.3.9. I had the same problem with error "Could not find ...org.codehaus.plexus...". The link provided here offered the solution in a comment by McKamey - simply delete M2_HOME (unset M2_HOME). Once I tried that, it all worked as expected.

This can be confirmed by visiting the Maven install page: "Add the bin directory of the created directory apache-maven-3.3.9 to the PATH environment variable" -- no mention of M2_HOME or M3_HOME at all.

Matplotlib connect scatterplot points with line - Python

In addition to what provided in the other answers, the keyword "zorder" allows one to decide the order in which different objects are plotted vertically. E.g.:

plt.plot(x,y,zorder=1) 
plt.scatter(x,y,zorder=2)

plots the scatter symbols on top of the line, while

plt.plot(x,y,zorder=2)
plt.scatter(x,y,zorder=1)

plots the line over the scatter symbols.

See, e.g., the zorder demo

jquery how to catch enter key and change event to tab

Here is what I've been using:

$("[tabindex]").addClass("TabOnEnter");
$(document).on("keypress", ".TabOnEnter", function (e) {
 //Only do something when the user presses enter
     if (e.keyCode == 13) {
          var nextElement = $('[tabindex="' + (this.tabIndex + 1) + '"]');
          console.log(this, nextElement);
           if (nextElement.length)
                nextElement.focus()
           else
                $('[tabindex="1"]').focus();
      }
});

Pays attention to the tabindex and is not specific to the form but to the whole page.

Note live has been obsoleted by jQuery, now you should be using on

Unstaged changes left after git reset --hard

Similar issue, although I'm sure only on surface. Anyway, it may help someone: what I did (FWIW, in SourceTree): stashed the uncommitted file, then did a hard reset.

Working with TIFFs (import, export) in Python using numpy

I recommend using the python bindings to OpenImageIO, it's the standard for dealing with various image formats in the vfx world. I've ovten found it more reliable in reading various compression types compared to PIL.

import OpenImageIO as oiio
input = oiio.ImageInput.open ("/path/to/image.tif")

How to empty/destroy a session in rails?

To clear only certain parameters, you can use:

[:param1, :param2, :param3].each { |k| session.delete(k) }

JavaScript - Replace all commas in a string

Just for fun:

var mystring = "this,is,a,test"  
var newchar = '|'
mystring = mystring.split(',').join(newchar);

Why is using the JavaScript eval function a bad idea?

It's generally only an issue if you're passing eval user input.

Matplotlib 2 Subplots, 1 Colorbar

The solution of using a list of axes by abevieiramota works very well until you use only one row of images, as pointed out in the comments. Using a reasonable aspect ratio for figsize helps, but is still far from perfect. For example:

import numpy as np
import matplotlib.pyplot as plt

fig, axes = plt.subplots(nrows=1, ncols=3, figsize=(9.75, 3))
for ax in axes.flat:
    im = ax.imshow(np.random.random((10,10)), vmin=0, vmax=1)

fig.colorbar(im, ax=axes.ravel().tolist())

plt.show()

1 x 3 image array

The colorbar function provides the shrink parameter which is a scaling factor for the size of the colorbar axes. It does require some manual trial and error. For example:

fig.colorbar(im, ax=axes.ravel().tolist(), shrink=0.75)

1 x 3 image array with shrunk colorbar

Android: How can I validate EditText input?

In order to reduce the verbosity of the validation logic I have authored a library for Android. It takes care of most of the day to day validations using Annotations and built-in rules. There are constraints such as @TextRule, @NumberRule, @Required, @Regex, @Email, @IpAddress, @Password, etc.,

You can add these annotations to your UI widget references and perform validations. It also allows you to perform validations asynchronously which is ideal for situations such as checking for unique username from a remote server.

There is a example on the project home page on how to use annotations. You can also read the associated blog post where I have written sample codes on how to write custom rules for validations.

Here is a simple example that depicts the usage of the library.

@Required(order = 1)
@Email(order = 2)
private EditText emailEditText;

@Password(order = 3)
@TextRule(order = 4, minLength = 6, message = "Enter at least 6 characters.")
private EditText passwordEditText;

@ConfirmPassword(order = 5)
private EditText confirmPasswordEditText;

@Checked(order = 6, message = "You must agree to the terms.")
private CheckBox iAgreeCheckBox;

The library is extendable, you can write your own rules by extending the Rule class.

Python multiprocessing PicklingError: Can't pickle <type 'function'>

Building on @rocksportrocker solution, It would make sense to dill when sending and RECVing the results.

import dill
import itertools
def run_dill_encoded(payload):
    fun, args = dill.loads(payload)
    res = fun(*args)
    res = dill.dumps(res)
    return res

def dill_map_async(pool, fun, args_list,
                   as_tuple=True,
                   **kw):
    if as_tuple:
        args_list = ((x,) for x in args_list)

    it = itertools.izip(
        itertools.cycle([fun]),
        args_list)
    it = itertools.imap(dill.dumps, it)
    return pool.map_async(run_dill_encoded, it, **kw)

if __name__ == '__main__':
    import multiprocessing as mp
    import sys,os
    p = mp.Pool(4)
    res = dill_map_async(p, lambda x:[sys.stdout.write('%s\n'%os.getpid()),x][-1],
                  [lambda x:x+1]*10,)
    res = res.get(timeout=100)
    res = map(dill.loads,res)
    print(res)

Format numbers to strings in Python

Starting with Python 3.6, formatting in Python can be done using formatted string literals or f-strings:

hours, minutes, seconds = 6, 56, 33
f'{hours:02}:{minutes:02}:{seconds:02} {"pm" if hours > 12 else "am"}'

or the str.format function starting with 2.7:

"{:02}:{:02}:{:02} {}".format(hours, minutes, seconds, "pm" if hours > 12 else "am")

or the string formatting % operator for even older versions of Python, but see the note in the docs:

"%02d:%02d:%02d" % (hours, minutes, seconds)

And for your specific case of formatting time, there’s time.strftime:

import time

t = (0, 0, 0, hours, minutes, seconds, 0, 0, 0)
time.strftime('%I:%M:%S %p', t)

#1025 - Error on rename of './database/#sql-2e0f_1254ba7' to './database/table' (errno: 150)

There is probably another table with a foreign key referencing the primary key you are trying to change.

To find out which table caused the error you can run SHOW ENGINE INNODB STATUS and then look at the LATEST FOREIGN KEY ERROR section.

How to concatenate strings in windows batch file for loop?

Try this, with strings:

set "var=string1string2string3"

and with string variables:

set "var=%string1%%string2%%string3%"

How to set some xlim and ylim in Seaborn lmplot facetgrid

You need to get hold of the axes themselves. Probably the cleanest way is to change your last row:

lm = sns.lmplot('X','Y',df,col='Z',sharex=False,sharey=False)

Then you can get hold of the axes objects (an array of axes):

axes = lm.axes

After that you can tweak the axes properties

axes[0,0].set_ylim(0,)
axes[0,1].set_ylim(0,)

creates:

enter image description here

How can I make a jQuery UI 'draggable()' div draggable for touchscreen?

I was struggling with a similar problem yesterday. I already had a "working" solution using jQuery UI's draggable together with jQuery Touch Punch, which are mentioned in other answers. However, using this method was causing weird bugs in some Android devices for me, and therefore I decided to write a small jQuery plugin that can make HTML elements draggable by using touch events instead of using a method that emulates fake mouse events.

The result of this is jQuery Draggable Touch which is a simple jQuery plugin for making elements draggable, that has touch devices as it's main target by using touch events (like touchstart, touchmove, touchend, etc.). It still has a fallback that uses mouse events if the browser/device doesn't support touch events.

How do I detect what .NET Framework versions and service packs are installed?

For a 64-bit OS, the path would be:

HKEY_LOCAL_MACHINE\SOFTWARE\wow6432Node\Microsoft\NET Framework Setup\NDP\

A simple command line to download a remote maven2 artifact to the local repository?

Give them a trivial pom with these jars listed as dependencies and instructions to run:

mvn dependency:go-offline

This will pull the dependencies to the local repo.

A more direct solution is dependency:get, but it's a lot of arguments to type:

mvn dependency:get -DrepoUrl=something -Dartifact=group:artifact:version

Difference between dates in JavaScript

    // This is for first date
    first = new Date(2010, 03, 08, 15, 30, 10); // Get the first date epoch object
    document.write((first.getTime())/1000); // get the actual epoch values
    second = new Date(2012, 03, 08, 15, 30, 10); // Get the first date epoch object
    document.write((second.getTime())/1000); // get the actual epoch values
    diff= second - first ;
    one_day_epoch = 24*60*60 ;  // calculating one epoch
    if ( diff/ one_day_epoch > 365 ) // check , is it exceei
    {
    alert( 'date is exceeding one year');
    }

How to add elements of a string array to a string array list?

Arrays.asList is bridge between Array and collection framework and it returns a fixed size List backed by Array.

species = Arrays.asList(speciesArr);

Obtaining ExitCode using Start-Process and WaitForExit instead of -Wait

While trying out the final suggestion above, I discovered an even simpler solution. All I had to do was cache the process handle. As soon as I did that, $process.ExitCode worked correctly. If I didn't cache the process handle, $process.ExitCode was null.

example:

$proc = Start-Process $msbuild -PassThru
$handle = $proc.Handle # cache proc.Handle
$proc.WaitForExit();

if ($proc.ExitCode -ne 0) {
    Write-Warning "$_ exited with status code $($proc.ExitCode)"
}

Reminder - \r\n or \n\r?

I'd use the word 'return' to remember, the r comes before the n.

Loading a .json file into c# program

Use Server.MapPath to get the actual path of the JSON file and load and read the file using StreamReader

using System;
using System.Collections.Generic;
using Newtonsoft.Json;

public class RootObject
{
    public string url_short { get; set; }
    public string url_long { get; set; }
    public int type { get; set; }
}

public class Program
{
    static public void Main()
    {
       using (StreamReader r = new StreamReader(Server.MapPath("~/test.json")))
       {
           string json = r.ReadToEnd();
           List<RootObject> ro = JsonConvert.DeserializeObject<List<RootObject>>(json);
       }

    Console.WriteLine(ro[0].url_short);                 
    }  
}

Note : Look below link also I have answered for question similar to this.It will be help full for you How to Parse an example string in C#

HashMap: One Key, multiple Values

Here is the code how to get extract the hashmap into arrays, hashmap that contains arraylist

Map<String, List<String>> country_hashmap = new HashMap<String, List<String>>();

//Creating two lists and inserting some data in it
List<String> list_1 = new ArrayList<String>();
list_1.add("16873538.webp");
list_1.add("16873539.webp");

List<String> list_2 = new ArrayList<String>();
list_2.add("16873540.webp");
list_2.add("16873541.webp");

//Inserting both the lists and key to the Map 
country_hashmap.put("Malaysia", list_1);
country_hashmap.put("Japanese", list_2);

for(Map.Entry<String, List<String>> hashmap_data : country_hashmap.entrySet()){
      String key = hashmap_data.getKey(); // contains the keys
      List<String> val = hashmap_data.getValue(); // contains arraylists
      // print all the key and values in the hashmap
      System.out.println(key + ": " +val);
      
      // using interator to get the specific values arraylists
      Iterator<String> itr = val.iterator();
      int i = 0;
      String[] data = new String[val.size()];
        while (itr.hasNext()){
            String array = itr.next();
            data[i] = array;
            System.out.println(data[i]); // GET THE VALUE
            i++;
        }
  }

How to cast DATETIME as a DATE in mysql?

Use DATE() function:

select * from follow_queue group by DATE(follow_date)

How can I test an AngularJS service from the console?

First of all, a modified version of your service.

a )

var app = angular.module('app',[]);

app.factory('ExampleService',function(){
    return {
        f1 : function(world){
            return 'Hello' + world;
        }
    };
});

This returns an object, nothing to new here.

Now the way to get this from the console is

b )

var $inj = angular.injector(['app']);
var serv = $inj.get('ExampleService');
serv.f1("World");

c )

One of the things you were doing there earlier was to assume that the app.factory returns you the function itself or a new'ed version of it. Which is not the case. In order to get a constructor you would either have to do

app.factory('ExampleService',function(){
        return function(){
            this.f1 = function(world){
                return 'Hello' + world;
            }
        };
    });

This returns an ExampleService constructor which you will next have to do a 'new' on.

Or alternatively,

app.service('ExampleService',function(){
            this.f1 = function(world){
                return 'Hello' + world;
            };
    });

This returns new ExampleService() on injection.

How to get value of a div using javascript

DIVs do not have a value property.

Technically, according to the DTDs, they shouldn't have a value attribute either, but generally you'll want to use .getAttribute() in this case:

function overlay()
{
    var cookieValue = document.getElementById('demo').getAttribute('value');
    alert(cookieValue);
}

How to view log output using docker-compose run?

Update July 1st 2019

docker-compose logs <name-of-service>

From the documentation:

Usage: logs [options] [SERVICE...]

Options:

--no-color Produce monochrome output.

-f, --follow Follow log output.

-t, --timestamps Show timestamps.

--tail="all" Number of lines to show from the end of the logs for each container.

See docker logs

You can start Docker compose in detached mode and attach yourself to the logs of all container later. If you're done watching logs you can detach yourself from the logs output without shutting down your services.

  1. Use docker-compose up -d to start all services in detached mode (-d) (you won't see any logs in detached mode)
  2. Use docker-compose logs -f -t to attach yourself to the logs of all running services, whereas -f means you follow the log output and the -t option gives you timestamps (See Docker reference)
  3. Use Ctrl + z or Ctrl + c to detach yourself from the log output without shutting down your running containers

If you're interested in logs of a single container you can use the docker keyword instead:

  1. Use docker logs -t -f <name-of-service>

Save the output

To save the output to a file you add the following to your logs command:

  1. docker-compose logs -f -t >> myDockerCompose.log

Install apps silently, with granted INSTALL_PACKAGES permission

I have been implementing installation without user consent recently - it was a kiosk application for API level 21+ where I had full control over environment.

The basic requirements are

  • API level 21+
  • root access to install the updater as a system privileged app.

The following method reads and installs APK from InputStream:

public static boolean installPackage(Context context, InputStream in, String packageName)
            throws IOException {
        PackageInstaller packageInstaller = context.getPackageManager().getPackageInstaller();
        PackageInstaller.SessionParams params = new PackageInstaller.SessionParams(
                PackageInstaller.SessionParams.MODE_FULL_INSTALL);
        params.setAppPackageName(packageName);
        // set params
        int sessionId = packageInstaller.createSession(params);
        PackageInstaller.Session session = packageInstaller.openSession(sessionId);
        OutputStream out = session.openWrite("COSU", 0, -1);
        byte[] buffer = new byte[65536];
        int c;
        while ((c = in.read(buffer)) != -1) {
            out.write(buffer, 0, c);
        }
        session.fsync(out);
        in.close();
        out.close();

        Intent intent = new Intent(context, MainActivity.class);
        intent.putExtra("info", "somedata");  // for extra data if needed..

        Random generator = new Random();

        PendingIntent i = PendingIntent.getActivity(context, generator.nextInt(), intent,PendingIntent.FLAG_UPDATE_CURRENT);
            session.commit(i.getIntentSender());


        return true;
    }

The following code calls the installation

 try {
     InputStream is = getResources().openRawResource(R.raw.someapk_source);
                    installPackage(MainActivity.this, is, "com.example.apk");
     } catch (IOException e) {
                    Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
     }

for the whole thing to work you desperately need INSTALL_PACKAGES permission, or the code above will fail silently

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

to get this permission you must install your APK as System application which REQUIRES root (however AFTER you have installed your updater application it seem to work WITHOUT root)

To install as system application I created a signed APK and pushed it with

adb push updater.apk /sdcard/updater.apk

and then moved it to system/priv-app - which requires remounting FS (this is why the root is required)

adb shell
su
mount -o rw,remount /system
mv /sdcard/updater.apk /system/priv-app
chmod 644 /system/priv-app/updater.apk

for some reason it didn't work with simple debug version, but logcat shows useful info if your application in priv-app is not picked up for some reason.

Bootstrap modal opening on page load

I found the problem. This code was placed in a separate file that was added with a php include() function. And this include was happening before the Bootstrap files were loaded. So the Bootstrap JS file was not loaded yet, causing this modal to not do anything.

With the above code sample is nothing wrong and works as intended when placed in the body part of a html page.

<script type="text/javascript">
$('#memberModal').modal('show');
</script>

Difference between $.ajax() and $.get() and $.load()

$.get = $.ajax({type: 'GET'});

$.load() is a helper function which only can be invoked on elements.

$.ajax() gives you most control. you can specify if you want to POST data, got more callbacks etc.

Looking to understand the iOS UIViewController lifecycle

iOS 10,11 (Swift 3.1,Swift 4.0)

According to UIViewController in UIKit developers,

1. loadView()

This is where subclasses should create their custom view hierarchy if they aren't using a nib. Should never be called directly.

2. loadViewIfNeeded()

Loads the view controller's view if it has not already been set.

3. viewDidLoad()

Called after the view has been loaded. For view controllers created in code, this is after -loadView. For view controllers unarchived from a nib, this is after the view is set.

4. viewWillAppear(_ animated: Bool)

Called when the view is about to made visible. Default does nothing

5. viewWillLayoutSubviews()

Called just before the view controller's view's layoutSubviews method is invoked. Subclasses can implement as necessary. Default does nothing.

6. viewDidLayoutSubviews()

Called just after the view controller's view's layoutSubviews method is invoked. Subclasses can implement as necessary. Default does nothing.

7. viewDidAppear(_ animated: Bool)

Called when the view has been fully transitioned onto the screen. Default does nothing

8. viewWillDisappear(_ animated: Bool)

Called when the view is dismissed, covered or otherwise hidden. Default does nothing

9. viewDidDisappear(_ animated: Bool)

Called after the view was dismissed, covered or otherwise hidden. Default does nothing

10. viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator)

Called when the view is Transitioning.

11. willMove(toParentViewController parent: UIViewController?)

12. didMove(toParentViewController parent: UIViewController?)

These two methods are public for container subclasses to call when transitioning between child controllers. If they are overridden, the overrides should ensure to call the super.

The parent argument in both of these methods is nil when a child is being removed from its parent; otherwise it is equal to the new parent view controller.

13. didReceiveMemoryWarning()

Called when the parent application receives a memory warning. On iOS 6.0 it will no longer clear the view by default.

Alternative to the HTML Bold tag

A very old thread, I know. - but for completeness:

I use <span class="bold">my text</span>    

as I upload the four font styles: normal; bold; italic and bold italic into my web-site via css.

I feel the resulting output is better than simply modifying a font and is closer to the designers intention of how the boldened font should look.

The same applies for italic and bolditalic of course, which gives me additional flexibility.

How to use wait and notify in Java without IllegalMonitorStateException?

To be able to call notify() you need to synchronize on the same object.

synchronized (someObject) {
    someObject.wait();
}

/* different thread / object */
synchronized (someObject) {
    someObject.notify();
}

Importing text file into excel sheet

There are many ways you can import Text file to the current sheet. Here are three (including the method that you are using above)

  1. Using a QueryTable
  2. Open the text file in memory and then write to the current sheet and finally applying Text To Columns if required.
  3. If you want to use the method that you are currently using then after you open the text file in a new workbook, simply copy it over to the current sheet using Cells.Copy

Using a QueryTable

Here is a simple macro that I recorded. Please amend it to suit your needs.

Sub Sample()
    With ActiveSheet.QueryTables.Add(Connection:= _
        "TEXT;C:\Sample.txt", Destination:=Range("$A$1") _
        )
        .Name = "Sample"
        .FieldNames = True
        .RowNumbers = False
        .FillAdjacentFormulas = False
        .PreserveFormatting = True
        .RefreshOnFileOpen = False
        .RefreshStyle = xlInsertDeleteCells
        .SavePassword = False
        .SaveData = True
        .AdjustColumnWidth = True
        .RefreshPeriod = 0
        .TextFilePromptOnRefresh = False
        .TextFilePlatform = 437
        .TextFileStartRow = 1
        .TextFileParseType = xlDelimited
        .TextFileTextQualifier = xlTextQualifierDoubleQuote
        .TextFileConsecutiveDelimiter = False
        .TextFileTabDelimiter = True
        .TextFileSemicolonDelimiter = False
        .TextFileCommaDelimiter = True
        .TextFileSpaceDelimiter = False
        .TextFileColumnDataTypes = Array(1, 1, 1, 1, 1, 1)
        .TextFileTrailingMinusNumbers = True
        .Refresh BackgroundQuery:=False
    End With
End Sub

Open the text file in memory

Sub Sample()
    Dim MyData As String, strData() As String

    Open "C:\Sample.txt" For Binary As #1
    MyData = Space$(LOF(1))
    Get #1, , MyData
    Close #1
    strData() = Split(MyData, vbCrLf)
End Sub

Once you have the data in the array you can export it to the current sheet.

Using the method that you are already using

Sub Sample()
    Dim wbI As Workbook, wbO As Workbook
    Dim wsI As Worksheet

    Set wbI = ThisWorkbook
    Set wsI = wbI.Sheets("Sheet1") '<~~ Sheet where you want to import

    Set wbO = Workbooks.Open("C:\Sample.txt")

    wbO.Sheets(1).Cells.Copy wsI.Cells

    wbO.Close SaveChanges:=False
End Sub

FOLLOWUP

You can use the Application.GetOpenFilename to choose the relevant file. For example...

Sub Sample()
    Dim Ret

    Ret = Application.GetOpenFilename("Prn Files (*.prn), *.prn")

    If Ret <> False Then
        With ActiveSheet.QueryTables.Add(Connection:= _
        "TEXT;" & Ret, Destination:=Range("$A$1"))

            '~~> Rest of the code

        End With
    End If
End Sub

Using getline() in C++

If you're using getline() after cin >> something, you need to flush the newline character out of the buffer in between. You can do it by using cin.ignore().

It would be something like this:

string messageVar;
cout << "Type your message: ";
cin.ignore(); 
getline(cin, messageVar);

This happens because the >> operator leaves a newline \n character in the input buffer. This may become a problem when you do unformatted input, like getline(), which reads input until a newline character is found. This happening, it will stop reading immediately, because of that \n that was left hanging there in your previous operation.

What's the difference between integer class and numeric class in R

First off, it is perfectly feasible to use R successfully for years and not need to know the answer to this question. R handles the differences between the (usual) numerics and integers for you in the background.

> is.numeric(1)

[1] TRUE

> is.integer(1)

[1] FALSE

> is.numeric(1L)

[1] TRUE

> is.integer(1L)

[1] TRUE

(Putting capital 'L' after an integer forces it to be stored as an integer.)

As you can see "integer" is a subset of "numeric".

> .Machine$integer.max

[1] 2147483647

> .Machine$double.xmax

[1] 1.797693e+308

Integers only go to a little more than 2 billion, while the other numerics can be much bigger. They can be bigger because they are stored as double precision floating point numbers. This means that the number is stored in two pieces: the exponent (like 308 above, except in base 2 rather than base 10), and the "significand" (like 1.797693 above).

Note that 'is.integer' is not a test of whether you have a whole number, but a test of how the data are stored.

One thing to watch out for is that the colon operator, :, will return integers if the start and end points are whole numbers. For example, 1:5 creates an integer vector of numbers from 1 to 5. You don't need to append the letter L.

> class(1:5)
[1] "integer"

Reference: https://www.quora.com/What-is-the-difference-between-numeric-and-integer-in-R

Using an HTTP PROXY - Python

Just wanted to mention, that you also may have to set the https_proxy OS environment variable in case https URLs need to be accessed. In my case it was not obvious to me and I tried for hours to discover this.

My use case: Win 7, jython-standalone-2.5.3.jar, setuptools installation via ez_setup.py

Is there a way to instantiate a class by name in Java?

Use java reflection

Creating New Objects There is no equivalent to method invocation for constructors, because invoking a constructor is equivalent to creating a new object (to be the most precise, creating a new object involves both memory allocation and object construction). So the nearest equivalent to the previous example is to say:

import java.lang.reflect.*;

   public class constructor2 {
      public constructor2()
      {
      }

      public constructor2(int a, int b)
      {
         System.out.println(
           "a = " + a + " b = " + b);
      }

      public static void main(String args[])
      {
         try {
           Class cls = Class.forName("constructor2");
           Class partypes[] = new Class[2];
            partypes[0] = Integer.TYPE;
            partypes[1] = Integer.TYPE;
            Constructor ct 
              = cls.getConstructor(partypes);
            Object arglist[] = new Object[2];
            arglist[0] = new Integer(37);
            arglist[1] = new Integer(47);
            Object retobj = ct.newInstance(arglist);
         }
         catch (Throwable e) {
            System.err.println(e);
         }
      }
   }

which finds a constructor that handles the specified parameter types and invokes it, to create a new instance of the object. The value of this approach is that it's purely dynamic, with constructor lookup and invocation at execution time, rather than at compilation time.

Removing leading zeroes from a field in a SQL statement

select substring(ColumnName, patindex('%[^0]%',ColumnName), 10)

How to quit android application programmatically

It depends on how fast you want to close your app.

A safe way to close your app is finishAffinity();

It closes you app after all processes finished processing. This may need some time. If you close your app this way, and restart it after a short time, it is possible that your new application runs in the same process. With all the not finished processes and singleton objects of the old application.

If you want to be sure, that your app is closed completly use System.exit(0);

This will close your app immediatly. But it is possible, that you damage files that your app has open or an edit on shared preferences does not finish. So use this carefully.

If you use watchdog in combination with a long running task, you can see the influences of the different methods.

new ANRWatchDog(2000).setANRListener(new ANRWatchDog.ANRListener() {
    public void onAppNotResponding(ANRError error) {
        MainActivity.this.finishAffinity();
        System.exit(0);
    }
}).start();
for(int i = 0; i < 10; ++i){
    --i;
}

This kills your app after 2 seconds without displaying an ANR dialog or something like that. If you remove System.exit(0), run this code and restart the app after it is closed, you will experience some strange behaviour, because the endless loop is still running.

CSS set li indent

to indent a ul dropdown menu, use

/* Main Level */
ul{
  margin-left:10px;
}

/* Second Level */
ul ul{
  margin-left:15px;
}

/* Third Level */
ul ul ul{
  margin-left:20px;
}

/* and so on... */

You can indent the lis and (if applicable) the as (or whatever content elements you have) as well , each with differing effects. You could also use padding-left instead of margin-left, again depending on the effect you want.

Update

By default, many browsers use padding-left to set the initial indentation. If you want to get rid of that, set padding-left: 0px;

Still, both margin-left and padding-left settings impact the indentation of lists in different ways. Specifically: margin-left impacts the indentation on the outside of the element's border, whereas padding-left affects the spacing on the inside of the element's border. (Learn more about the CSS box model here)

Setting padding-left: 0; leaves the li's bullet icons hanging over the edge of the element's border (at least in Chrome), which may or may not be what you want.

Examples of padding-left vs margin-left and how they can work together on ul: https://jsfiddle.net/daCrosby/bb7kj8cr/1/

ASP.NET Core Web API Authentication

I have implemented BasicAuthenticationHandler for basic authentication so you can use it with standart attributes Authorize and AllowAnonymous.

public class BasicAuthenticationHandler : AuthenticationHandler<BasicAuthenticationOptions>
{
    protected override Task<AuthenticateResult> HandleAuthenticateAsync()
    {
        var authHeader = (string)this.Request.Headers["Authorization"];

        if (!string.IsNullOrEmpty(authHeader) && authHeader.StartsWith("basic", StringComparison.OrdinalIgnoreCase))
        {
            //Extract credentials
            string encodedUsernamePassword = authHeader.Substring("Basic ".Length).Trim();
            Encoding encoding = Encoding.GetEncoding("iso-8859-1");
            string usernamePassword = encoding.GetString(Convert.FromBase64String(encodedUsernamePassword));

            int seperatorIndex = usernamePassword.IndexOf(':', StringComparison.OrdinalIgnoreCase);

            var username = usernamePassword.Substring(0, seperatorIndex);
            var password = usernamePassword.Substring(seperatorIndex + 1);

            //you also can use this.Context.Authentication here
            if (username == "test" && password == "test")
            {
                var user = new GenericPrincipal(new GenericIdentity("User"), null);
                var ticket = new AuthenticationTicket(user, new AuthenticationProperties(), Options.AuthenticationScheme);
                return Task.FromResult(AuthenticateResult.Success(ticket));
            }
            else
            {
                return Task.FromResult(AuthenticateResult.Fail("No valid user."));
            }
        }

        this.Response.Headers["WWW-Authenticate"]= "Basic realm=\"yourawesomesite.net\"";
        return Task.FromResult(AuthenticateResult.Fail("No credentials."));
    }
}

public class BasicAuthenticationMiddleware : AuthenticationMiddleware<BasicAuthenticationOptions>
{
    public BasicAuthenticationMiddleware(
       RequestDelegate next,
       IOptions<BasicAuthenticationOptions> options,
       ILoggerFactory loggerFactory,
       UrlEncoder encoder)
       : base(next, options, loggerFactory, encoder)
    {
    }

    protected override AuthenticationHandler<BasicAuthenticationOptions> CreateHandler()
    {
        return new BasicAuthenticationHandler();
    }
}

public class BasicAuthenticationOptions : AuthenticationOptions
{
    public BasicAuthenticationOptions()
    {
        AuthenticationScheme = "Basic";
        AutomaticAuthenticate = true;
    }
}

Registration at Startup.cs - app.UseMiddleware<BasicAuthenticationMiddleware>();. With this code, you can restrict any controller with standart attribute Autorize:

[Authorize(ActiveAuthenticationSchemes = "Basic")]
[Route("api/[controller]")]
public class ValuesController : Controller

and use attribute AllowAnonymous if you apply authorize filter on application level.

Not able to pip install pickle in python 3.6

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

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

import pickle
print(pickle.__doc__)

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

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

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

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

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

Removing character in list of strings

Try this:

lst = [("aaaa8"),("bb8"),("ccc8"),("dddddd8")]
print([s.strip('8') for s in lst]) # remove the 8 from the string borders
print([s.replace('8', '') for s in lst]) # remove all the 8s 

Effectively use async/await with ASP.NET Web API

I would change your service layer to:

public Task<BackOfficeResponse<List<Country>>> ReturnAllCountries()
{
    return Task.Run(() =>
    {
        return _service.Process<List<Country>>(BackOfficeEndpoint.CountryEndpoint, "returnCountries");
    }      
}

as you have it, you are still running your _service.Process call synchronously, and gaining very little or no benefit from awaiting it.

With this approach, you are wrapping the potentially slow call in a Task, starting it, and returning it to be awaited. Now you get the benefit of awaiting the Task.

Can I underline text in an Android layout?

HtmlCompat.fromHtml(
                    String.format(context.getString(R.string.set_target_with_underline)),
                    HtmlCompat.FROM_HTML_MODE_LEGACY)
<string name="set_target_with_underline">&lt;u>Set Target&lt;u> </string>

Note the Escape symbol in xml file

postgresql return 0 if returned value is null

(this answer was added to provide shorter and more generic examples to the question - without including all the case-specific details in the original question).


There are two distinct "problems" here, the first is if a table or subquery has no rows, the second is if there are NULL values in the query.

For all versions I've tested, postgres and mysql will ignore all NULL values when averaging, and it will return NULL if there is nothing to average over. This generally makes sense, as NULL is to be considered "unknown". If you want to override this you can use coalesce (as suggested by Luc M).

$ create table foo (bar int);
CREATE TABLE

$ select avg(bar) from foo;
 avg 
-----

(1 row)

$ select coalesce(avg(bar), 0) from foo;
 coalesce 
----------
        0
(1 row)

$ insert into foo values (3);
INSERT 0 1
$ insert into foo values (9);
INSERT 0 1
$ insert into foo values (NULL);
INSERT 0 1
$ select coalesce(avg(bar), 0) from foo;
      coalesce      
--------------------
 6.0000000000000000
(1 row)

of course, "from foo" can be replaced by "from (... any complicated logic here ...) as foo"

Now, should the NULL row in the table be counted as 0? Then coalesce has to be used inside the avg call.

$ select coalesce(avg(coalesce(bar, 0)), 0) from foo;
      coalesce      
--------------------
 4.0000000000000000
(1 row)

How do I debug Windows services in Visual Studio?

You should separate out all the code that will do stuff from the service project into a separate project, and then make a test application that you can run and debug normally.

The service project would be just the shell needed to implement the service part of it.

Get root password for Google Cloud Engine VM

I tried "ManiIOT"'s solution and it worked surprisingly. I've added another role (Compute Admin Role) for my google user account from IAM admin. Then stopped and restarted the VM. Afterwards 'sudo passwd' let me to generate a new password for the user.

So here are steps.

  1. Go to IAM & Admin
  2. Select IAM
  3. Find your user name service account (basically your google account) and click Edit-member
  4. Add another role --> select 'Compute Engine' - 'Compute Admin'
  5. Restart your Compute VM
  6. open SSH shell and run the command 'sudo passwd'
  7. enter a brand new password. Voilà!

How to set all elements of an array to zero or any same value?

You could use memset, if you sure about the length.

memset(ptr, 0x00, length)

Forward slash in Java Regex

The problem is actually that you need to double-escape backslashes in the replacement string. You see, "\\/" (as I'm sure you know) means the replacement string is \/, and (as you probably don't know) the replacement string \/ actually just inserts /, because Java is weird, and gives \ a special meaning in the replacement string. (It's supposedly so that \$ will be a literal dollar sign, but I think the real reason is that they wanted to mess with people. Other languages don't do it this way.) So you have to write either:

"Hello/You/There".replaceAll("/", "\\\\/");

or:

"Hello/You/There".replaceAll("/", Matcher.quoteReplacement("\\/"));

(Using java.util.regex.Matcher.quoteReplacement(String).)

How can I merge properties of two JavaScript objects dynamically?

Just if anyone is using Google Closure Library:

goog.require('goog.object');
var a = {'a': 1, 'b': 2};
var b = {'b': 3, 'c': 4};
goog.object.extend(a, b);
// Now object a == {'a': 1, 'b': 3, 'c': 4};

Similar helper function exists for array:

var a = [1, 2];
var b = [3, 4];
goog.array.extend(a, b); // Extends array 'a'
goog.array.concat(a, b); // Returns concatenation of array 'a' and 'b'

Using number_format method in Laravel

This should work :

<td>{{ number_format($Expense->price, 2) }}</td>

How to update data in one table from corresponding data in another table in SQL Server 2005

update test1 t1, test2 t2
set t2.deptid = t1.deptid
where t2.employeeid = t1.employeeid

you can not use from keyword for the mysql

Powershell: A positional parameter cannot be found that accepts argument "xxx"

Cmdlets in powershell accept a bunch of arguments. When these arguments are defined you can define a position for each of them.

This allows you to call a cmdlet without specifying the parameter name. So for the following cmdlet the path attribute is define with a position of 0 allowing you to skip typing -Path when invoking it and as such both the following will work.

Get-Item -Path C:\temp\thing.txt
Get-Item C:\temp\thing.txt

However if you specify more arguments than there are positional parameters defined then you will get the error.

Get-Item C:\temp\thing.txt "*"

As this cmdlet does not know how to accept the second positional parameter you get the error. You can fix this by telling it what the parameter is meant to be.

Get-Item C:\temp\thing.txt -Filter "*"

I assume you are getting the error on the following line of code as it seems to be the only place you are not specifying the parameter names correctly, and maybe it is treating the = as a parameter and $username as another parameter.

Set-ADUser $user -userPrincipalName = $newname

Try specifying the parameter name for $user and removing the =

MySQL Error: #1142 - SELECT command denied to user

You need to give privileges to the particular user by giving the command mysql> GRANT ALL PRIVILEGES . To 'username'@'localhost'; and then give FLUSH PRIVILEGES; command. Then it won't give this error.., hope it helps thank you..!

how to rotate a bitmap 90 degrees

Below is the code to rotate or re size your image in android

public class bitmaptest extends Activity {
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        LinearLayout linLayout = new LinearLayout(this);

        // load the origial BitMap (500 x 500 px)
        Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
               R.drawable.android);

        int width = bitmapOrg.width();
        int height = bitmapOrg.height();
        int newWidth = 200;
        int newHeight = 200;

        // calculate the scale - in this case = 0.4f
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;

        // createa matrix for the manipulation
        Matrix matrix = new Matrix();
        // resize the bit map
        matrix.postScale(scaleWidth, scaleHeight);
        // rotate the Bitmap
        matrix.postRotate(45);

        // recreate the new Bitmap
        Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
                          width, height, matrix, true);

        // make a Drawable from Bitmap to allow to set the BitMap
        // to the ImageView, ImageButton or what ever
        BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);

        ImageView imageView = new ImageView(this);

        // set the Drawable on the ImageView
        imageView.setImageDrawable(bmd);

        // center the Image
        imageView.setScaleType(ScaleType.CENTER);

        // add ImageView to the Layout
        linLayout.addView(imageView,
                new LinearLayout.LayoutParams(
                      LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
                )
        );

        // set LinearLayout as ContentView
        setContentView(linLayout);
    }
}

You can also check this link for details : http://www.anddev.org/resize_and_rotate_image_-_example-t621.html

How to assert greater than using JUnit Assert?

Alternatively if adding extra library such as hamcrest is not desirable, the logic can be implemented as utility method using junit dependency only:

public static void assertGreaterThan(int greater, int lesser) {
    assertGreaterThan(greater, lesser, null);
}

public static void assertGreaterThan(int greater, int lesser, String message) {
    if (greater <= lesser) {
        fail((StringUtils.isNotBlank(message) ? message + " ==> " : "") +
                "Expected: a value greater than <" + lesser + ">\n" +
                "But <" + greater + "> was " + (greater == lesser ? "equal to" : "less than") + " <" + lesser + ">");
    }
}

Error message 'Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.'

In case none of the other answers help you:

When I had this problem, it turned out my Windows service was built for an x64 platform, and I was inadvertently running the 32-bit version of InstallUtil.exe. So make sure you're using the right version of InstallUtil for the platform you built for.

Is calculating an MD5 hash less CPU intensive than SHA family functions?

sha1sum is quite a bit faster on Power9 than md5sum

$ uname -mov
#1 SMP Mon May 13 12:16:08 EDT 2019 ppc64le GNU/Linux

$ cat /proc/cpuinfo
processor       : 0
cpu             : POWER9, altivec supported
clock           : 2166.000000MHz
revision        : 2.2 (pvr 004e 1202)

$ ls -l linux-master.tar
-rw-rw-r-- 1 x x 829685760 Jan 29 14:30 linux-master.tar

$ time sha1sum linux-master.tar
10fbf911e254c4fe8e5eb2e605c6c02d29a88563  linux-master.tar

real    0m1.685s
user    0m1.528s
sys     0m0.156s

$ time md5sum linux-master.tar
d476375abacda064ae437a683c537ec4  linux-master.tar

real    0m2.942s
user    0m2.806s
sys     0m0.136s

$ time sum linux-master.tar
36928 810240

real    0m2.186s
user    0m1.917s
sys     0m0.268s

C# Reflection: How to get class reference from string?

Bit late for reply but this should do the trick

Type myType = Type.GetType("AssemblyQualifiedName");

your assembly qualified name should be like this

"Boom.Bam.Class, Boom.Bam, Version=1.0.0.262, Culture=neutral, PublicKeyToken=e16dba1a3c4385bd"

Is there an alternative to string.Replace that is case-insensitive?

The regular expression method should work. However what you can also do is lower case the string from the database, lower case the %variables% you have, and then locate the positions and lengths in the lower cased string from the database. Remember, positions in a string don't change just because its lower cased.

Then using a loop that goes in reverse (its easier, if you do not you will have to keep a running count of where later points move to) remove from your non-lower cased string from the database the %variables% by their position and length and insert the replacement values.

JavaScript Array splice vs slice

Splice and Slice are built-in Javascript commands -- not specifically AngularJS commands. Slice returns array elements from the "start" up until just before the "end" specifiers. Splice mutates the actual array, and starts at the "start" and keeps the number of elements specified. Google has plenty of info on this, just search.

Logcat not displaying my log calls

After upgrade to Android 3.6.1, I have experienced this issue multiple times. The only thing that works in my case is RESTARTING THE DEVICE.

JavaScript: Is there a way to get Chrome to break on all errors?

This is now supported in Chrome by the "Pause on all exceptions" button.

To enable it:

  • Go to the "Sources" tab in Chrome Developer Tools
  • Click the "Pause" button at the bottom of the window to switch to "Pause on all exceptions mode".

Note that this button has multiple states. Keep clicking the button to switch between

  • "Pause on all exceptions" - the button is colored light blue
  • "Pause on uncaught exceptions", the button is colored purple.
  • "Dont pause on exceptions" - the button is colored gray

How to call loading function with React useEffect only once

If you only want to run the function given to useEffect after the initial render, you can give it an empty array as second argument.

function MyComponent() {
  useEffect(() => {
    loadDataOnlyOnce();
  }, []);

  return <div> {/* ... */} </div>;
}

how to clear the screen in python

If you mean the screen where you have that interpreter prompt >>> you can do CTRL+L on Bash shell can help. Windows does not have equivalent. You can do

import os
os.system('cls')  # on windows

or

os.system('clear')  # on linux / os x

git pull remote branch cannot find remote ref

You need to set your local branch to track the remote branch, which it won't do automatically if they have different capitalizations.

Try:

git branch --set-upstream downloadmanager origin/DownloadManager
git pull

UPDATE:

'--set-upstream' option is no longer supported.

git branch --set-upstream-to downloadmanager origin/DownloadManager
git pull

Using 'sudo apt-get install build-essentials'

Try

sudo apt-get update
sudo apt-get install build-essential

(If I recall correctly the package name is without the extra s at the end).

error MSB6006: "cmd.exe" exited with code 1

Navigate from Error List Tab to the Visual Studios Output folder by one of the following:

  • Select tab Output in standard VS view at the bottom
  • Click in Menubar View > Output or Ctrl+Alt+O

where Show output from <build> should be selected.

You can find out more by analyzing the output logs.


In my case it was an error in the Cmake step, see below. It could be in any build step, as described in the other answers.

> -- Build Type is debug 
> CMake Error in CMakeLists.txt:
>     A logical block opening on the line
>     <path_to_file:line_number>    
>     is not closed.

Docker is in volume in use, but there aren't any Docker containers

I am pretty sure that those volumes are actually mounted on your system. Look in /proc/mounts and you will see them there. You will likely need to sudo umount <path> or sudo umount -f -n <path>. You should be able to get the mounted path either in /proc/mounts or through docker volume inspect

Accessing @attribute from SimpleXML

Try this

$xml->attributes()->Token

How to for each the hashmap?

You can iterate over a HashMap (and many other collections) using an iterator, e.g.:

HashMap<T,U> map = new HashMap<T,U>();

...

Iterator it = map.values().iterator();

while (it.hasNext()) {
    System.out.println(it.next());
}

org.hibernate.MappingException: Could not determine type for: java.util.List, at table: College, for columns: [org.hibernate.mapping.Column(students)]

You are using field access strategy (determined by @Id annotation). Put any JPA related annotation right above each field instead of getter property

@OneToMany(targetEntity=Student.class, mappedBy="college", fetch=FetchType.EAGER)
private List<Student> students;

Class JavaLaunchHelper is implemented in both ... libinstrument.dylib. One of the two will be used. Which one is undefined

As other answers detail, this is a bug in the JDK (up to u45) which will be fixed in JDK7u60 - while this is not out yet, you may download the b01 from: https://jdk7.java.net/download.html

It's beta, but fixed that issue for me.

CSS: create white glow around image

late to the party here; however just wanted to add a bit of extra fun..

box-shadow: 0px 0px 5px rgba(0,0,0,.3);
padding:7px;

will give you a nice looking padded in image. The padding will give you a simulated white border (or whatever border you have set). the rgba is just allowing you to do an opicity on the particular color; 0,0,0 being black. You could just as easily use any other RGB color.

Hope this helps someone!

UIButton: set image for selected-highlighted state

You can do this in Interface Builder.

Select the UIButton you wish to set in IB then go to the attributes inspector.

In the screen shots,I am using a custom button type , but that does not matter.

Custom Default

enter image description here

enter image description here