Programs & Examples On #Sl4a

Scripting Layer for Android, a library for executing scripting languages on Android

How do I convert a datetime to date?

import time
import datetime

# use mktime to step by one day
# end - the last day, numdays - count of days to step back
def gen_dates_list(end, numdays):
  start = end - datetime.timedelta(days=numdays+1)
  end   = int(time.mktime(end.timetuple()))
  start = int(time.mktime(start.timetuple()))
  # 86400 s = 1 day
  return xrange(start, end, 86400)

# if you need reverse the list of dates
for dt in reversed(gen_dates_list(datetime.datetime.today(), 100)):
    print datetime.datetime.fromtimestamp(dt).date()

ExecutorService that interrupts tasks after a timeout

After ton of time to survey,
Finally, I use invokeAll method of ExecutorService to solve this problem.
That will strictly interrupt the task while task running.
Here is example

ExecutorService executorService = Executors.newCachedThreadPool();

try {
    List<Callable<Object>> callables = new ArrayList<>();
    // Add your long time task (callable)
    callables.add(new VaryLongTimeTask());
    // Assign tasks for specific execution timeout (e.g. 2 sec)
    List<Future<Object>> futures = executorService.invokeAll(callables, 2000, TimeUnit.MILLISECONDS);
    for (Future<Object> future : futures) {
        // Getting result
    }
} catch (InterruptedException e) {
    e.printStackTrace();
}

executorService.shutdown();

The pro is you can also submit ListenableFuture at the same ExecutorService.
Just slightly change the first line of code.

ListeningExecutorService executorService = MoreExecutors.listeningDecorator(Executors.newCachedThreadPool());

ListeningExecutorService is the Listening feature of ExecutorService at google guava project (com.google.guava) )

<button> vs. <input type="button" />. Which to use?

Quoting the Forms Page in the HTML manual:

Buttons created with the BUTTON element function just like buttons created with the INPUT element, but they offer richer rendering possibilities: the BUTTON element may have content. For example, a BUTTON element that contains an image functions like and may resemble an INPUT element whose type is set to "image", but the BUTTON element type allows content.

Run a PHP file in a cron job using CPanel

This works fine and also sends email:

/usr/bin/php /home/xxYourUserNamexx/public_html/xxYourFolderxx/xxcronfile.php

The following two commands also work fine but do not send email:

/usr/bin/php -f /home/Same As Above

php -f /home/Same As Above

Set timeout for webClient.DownloadFile()

My answer comes from here

You can make a derived class, which will set the timeout property of the base WebRequest class:

using System;
using System.Net;

public class WebDownload : WebClient
{
    /// <summary>
    /// Time in milliseconds
    /// </summary>
    public int Timeout { get; set; }

    public WebDownload() : this(60000) { }

    public WebDownload(int timeout)
    {
        this.Timeout = timeout;
    }

    protected override WebRequest GetWebRequest(Uri address)
    {
        var request = base.GetWebRequest(address);
        if (request != null)
        {
            request.Timeout = this.Timeout;
        }
        return request;
    }
}

and you can use it just like the base WebClient class.

Using SVG as background image

Try placing it on your body

body {
    height: 100%;
    background-image: url(../img/bg.svg);
    background-size:100% 100%;
    -o-background-size: 100% 100%;
    -webkit-background-size: 100% 100%;
    background-size:cover;
}

How to reset / remove chrome's input highlighting / focus border?

The simpliest way is to use something like this but note that it may not be that good.

input {
  outline: none;
}

I hope you find this useful.

How to install SQL Server 2005 Express in Windows 8

install "SQL Express 2005 service pack 4" version "directly".

it contains sql Express 2005 inside . dont let the name fool you

runs succesfuly. from my experince

enter image description here

Everytime I run gulp anything, I get a assertion error. - Task function must be specified

https://fettblog.eu/gulp-4-parallel-and-series/

Because gulp.task(name, deps, func) was replaced by gulp.task(name, gulp.{series|parallel}(deps, func)).

You are using the latest version of gulp but older code. Modify the code or downgrade.

Difference between the System.Array.CopyTo() and System.Array.Clone()

The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identical object.

So the difference are :

1- CopyTo require to have a destination array when Clone return a new array.
2- CopyTo let you specify an index (if required) to the destination array.
Edit:

Remove the wrong example.

Sorting an array in C?

In your particular case the fastest sort is probably the one described in this answer. It is exactly optimized for an array of 6 ints and uses sorting networks. It is 20 times (measured on x86) faster than library qsort. Sorting networks are optimal for sort of fixed length arrays. As they are a fixed sequence of instructions they can even be implemented easily by hardware.

Generally speaking there is many sorting algorithms optimized for some specialized case. The general purpose algorithms like heap sort or quick sort are optimized for in place sorting of an array of items. They yield a complexity of O(n.log(n)), n being the number of items to sort.

The library function qsort() is very well coded and efficient in terms of complexity, but uses a call to some comparizon function provided by user, and this call has a quite high cost.

For sorting very large amount of datas algorithms have also to take care of swapping of data to and from disk, this is the kind of sorts implemented in databases and your best bet if you have such needs is to put datas in some database and use the built in sort.

Turn off warnings and errors on PHP and MySQL

You can set the type of error reporting you need in php.ini or by using the error_reporting() function on top of your script.

Get a json via Http Request in NodeJS

Just tell request that you are using json:true and forget about header and parse

var options = {
    hostname: '127.0.0.1',
    port: app.get('port'),
    path: '/users',
    method: 'GET',
    json:true
}
request(options, function(error, response, body){
    if(error) console.log(error);
    else console.log(body);
});

and the same for post

var options = {
    hostname: '127.0.0.1',
    port: app.get('port'),
    path: '/users',
    method: 'POST',
    json: {"name":"John", "lastname":"Doe"}
}
request(options, function(error, response, body){
    if(error) console.log(error);
    else console.log(body);
});

Ruby: Easiest Way to Filter Hash Keys?

As for bonus question:

  1. If you have output from #select method like this (list of 2-element arrays):

    [[:choice1, "Oh look, another one"], [:choice2, "Even more strings"], [:choice3, "But wait"]]
    

    then simply take this result and execute:

    filtered_params.join("\t")
    # or if you want only values instead of pairs key-value
    filtered_params.map(&:last).join("\t")
    
  2. If you have output from #delete_if method like this (hash):

    {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
    

    then:

    filtered_params.to_a.join("\t")
    # or
    filtered_params.values.join("\t")
    

Address already in use: JVM_Bind java

Address already in use: JVM_Bind

means that some other application is already listening on the port your current application is trying to bind.

what you need to do is, either change the port for your current application or better; just find out the already running application and kill it.

on Linux you can find the application pid by using,

netstat -tulpn

Binding a list in @RequestParam

Or you could just do it that way:

public String controllerMethod(@RequestParam(value="myParam[]") String[] myParams){
    ....
}

That works for example for forms like this:

<input type="checkbox" name="myParam[]" value="myVal1" />
<input type="checkbox" name="myParam[]" value="myVal2" />

This is the simplest solution :)

How to wait for all threads to finish, using ExecutorService?

You could wrap your tasks in another runnable, that will send notifications:

taskExecutor.execute(new Runnable() {
  public void run() {
    taskStartedNotification();
    new MyTask().run();
    taskFinishedNotification();
  }
});

Visual C++ executable and missing MSVCR100d.dll

You definitely should not need the debug version of the CRT if you're compiling in "release" mode. You can tell they're the debug versions of the DLLs because they end with a d.

More to the point, the debug version is not redistributable, so it's not as simple as "packaging" it with your executable, or zipping up those DLLs.

Check to be sure that you're compiling all components of your application in "release" mode, and that you're linking the correct version of the CRT and any other libraries you use (e.g., MFC, ATL, etc.).

You will, of course, require msvcr100.dll (note the absence of the d suffix) and some others if they are not already installed. Direct your friends to download the Visual C++ 2010 Redistributable (or x64), or include this with your application automatically by building an installer.

How can I turn a string into a list in Python?

The list() function [docs] will convert a string into a list of single-character strings.

>>> list('hello')
['h', 'e', 'l', 'l', 'o']

Even without converting them to lists, strings already behave like lists in several ways. For example, you can access individual characters (as single-character strings) using brackets:

>>> s = "hello"
>>> s[1]
'e'
>>> s[4]
'o'

You can also loop over the characters in the string as you can loop over the elements of a list:

>>> for c in 'hello':
...     print c + c,
... 
hh ee ll ll oo

Remove char at specific index - python

Use slicing, rebuilding the string minus the index you want to remove:

newstr = oldstr[:4] + oldstr[5:]

What does it mean: The serializable class does not declare a static final serialVersionUID field?

From the javadoc:

The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. If the receiver has loaded a class for the object that has a different serialVersionUID than that of the corresponding sender's class, then deserialization will result in an InvalidClassException. A serializable class can declare its own serialVersionUID explicitly by declaring a field named "serialVersionUID" that must be static, final, and of type long:

You can configure your IDE to:

  • ignore this, instead of giving a warning.
  • autogenerate an id

As per your additional question "Can it be that the discussed warning message is a reason why my GUI application freeze?":

No, it can't be. It can cause a problem only if you are serializing objects and deserializing them in a different place (or time) where (when) the class has changed, and it will not result in freezing, but in InvalidClassException.

Error in finding last used cell in Excel with VBA

However this question is seeking to find the last row using VBA, I think it would be good to include an array formula for worksheet function as this gets visited frequently:

{=ADDRESS(MATCH(INDEX(D:D,MAX(IF(D:D<>"",ROW(D:D)-ROW(D1)+1)),1),D:D,0),COLUMN(D:D))}

You need to enter the formula without brackets and then hit Shift + Ctrl + Enter to make it an array formula.

This will give you address of last used cell in the column D.

Maven artifact and groupId naming

Consider this to get a fully unique jar file:

  • GroupID - com.companyname.project
  • ArtifactId - com-companyname-project
  • Package - com.companyname.project

How to make circular background using css?

If you want to do it with only 1 element, you can use the ::before and ::after pseudo elements for the same div instead of a wrapper.
See http://css-tricks.com/pseudo-element-roundup/

Spring @ContextConfiguration how to put the right location for the xml

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = {"/Beans.xml"}) public class DemoTest{}

What are the basic rules and idioms for operator overloading?

The Decision between Member and Non-member

The binary operators = (assignment), [] (array subscription), -> (member access), as well as the n-ary () (function call) operator, must always be implemented as member functions, because the syntax of the language requires them to.

Other operators can be implemented either as members or as non-members. Some of them, however, usually have to be implemented as non-member functions, because their left operand cannot be modified by you. The most prominent of these are the input and output operators << and >>, whose left operands are stream classes from the standard library which you cannot change.

For all operators where you have to choose to either implement them as a member function or a non-member function, use the following rules of thumb to decide:

  1. If it is a unary operator, implement it as a member function.
  2. If a binary operator treats both operands equally (it leaves them unchanged), implement this operator as a non-member function.
  3. If a binary operator does not treat both of its operands equally (usually it will change its left operand), it might be useful to make it a member function of its left operand’s type, if it has to access the operand's private parts.

Of course, as with all rules of thumb, there are exceptions. If you have a type

enum Month {Jan, Feb, ..., Nov, Dec}

and you want to overload the increment and decrement operators for it, you cannot do this as a member functions, since in C++, enum types cannot have member functions. So you have to overload it as a free function. And operator<() for a class template nested within a class template is much easier to write and read when done as a member function inline in the class definition. But these are indeed rare exceptions.

(However, if you make an exception, do not forget the issue of const-ness for the operand that, for member functions, becomes the implicit this argument. If the operator as a non-member function would take its left-most argument as a const reference, the same operator as a member function needs to have a const at the end to make *this a const reference.)


Continue to Common operators to overload.

Storing images in SQL Server?

There's a really good paper by Microsoft Research called To Blob or Not To Blob.

Their conclusion after a large number of performance tests and analysis is this:

  • if your pictures or document are typically below 256KB in size, storing them in a database VARBINARY column is more efficient

  • if your pictures or document are typically over 1 MB in size, storing them in the filesystem is more efficient (and with SQL Server 2008's FILESTREAM attribute, they're still under transactional control and part of the database)

  • in between those two, it's a bit of a toss-up depending on your use

If you decide to put your pictures into a SQL Server table, I would strongly recommend using a separate table for storing those pictures - do not store the employee photo in the employee table - keep them in a separate table. That way, the Employee table can stay lean and mean and very efficient, assuming you don't always need to select the employee photo, too, as part of your queries.

For filegroups, check out Files and Filegroup Architecture for an intro. Basically, you would either create your database with a separate filegroup for large data structures right from the beginning, or add an additional filegroup later. Let's call it "LARGE_DATA".

Now, whenever you have a new table to create which needs to store VARCHAR(MAX) or VARBINARY(MAX) columns, you can specify this file group for the large data:

 CREATE TABLE dbo.YourTable
     (....... define the fields here ......)
     ON Data                   -- the basic "Data" filegroup for the regular data
     TEXTIMAGE_ON LARGE_DATA   -- the filegroup for large chunks of data

Check out the MSDN intro on filegroups, and play around with it!

clear cache of browser by command line

You can run Rundll32.exe for IE Options control panel applet and achieve following tasks.


Deletes ALL History - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 255

Deletes History Only - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 1

Deletes Cookies Only - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 2

Deletes Temporary Internet Files Only - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 8

Deletes Form Data Only - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 16

Deletes Password History Only - RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 32

Valid to use <a> (anchor tag) without href attribute?

It is valid. You can, for example, use it to show modals (or similar things that respond to data-toggle and data-target attributes).

Something like:

<a role="button" data-toggle="modal" data-target=".bs-example-modal-sm" aria-hidden="true"><i class="fa fa-phone"></i></a>

Here I use the font-awesome icon, which is better as a a tag rather than a button, to show a modal. Also, setting role="button" makes the pointer change to an action type. Without either href or role="button", the cursor pointer does not change.

How can I check the system version of Android?

For example, a feature only works for api21 up the following we fix bugs in api21 down

    if(Build.VERSION.SDK_INT >= 21) {
    //only api 21 above
    }else{
   //only api 21 down
    }

Java Byte Array to String to Byte Array

[JAVA 8]

import java.util.Base64;

String dummy= "dummy string";
byte[] byteArray = dummy.getBytes();

byte[] salt = new byte[]{ -47, 1, 16, ... }
String encoded = Base64.getEncoder().encodeToString(salt);

What is Domain Driven Design?

DDD(domain driven design) is a useful concept for analyse of requirements of a project and handling the complexity of these requirements.Before that people were analysing these requirements with considering the relationships between classes and tables and in fact their design were based on database tables relationships it is not old but it has some problems:

  • In big projects with complex requirements it is not useful although this is a great way of design for small projects.

  • when you are dealing with none technical persons that they don,t have technical concept, this conflict may cause some huge problems in our project.

So DDD handle the first problem with considering the main project as a Domain and splitting each part of this project to small pieces which we are famous to Bounded Context and each of them do not have any influence on other pieces. And the second problem has been solved with a ubiquitous language which is a common language between technical team members and Product owners which are not technical but have enough knowledge about their requirements

Generally the simple definition for Domain is the main project that makes money for the owners and other teams.

Abstract Class vs Interface in C++

interface were primarily made popular by Java.
Below are the nature of interface and its C++ equivalents:

  1. interface can contain only body-less abstract methods; C++ equivalent is pure virtual methods, though they can/cannot have body
  2. interface can contain only static final data members; C++ equivalent is static const data members which are compile time constants
  3. Multiple interface can be implemented by a Java class, this facility is needed because a Java class can inherit only 1 class; C++ supports multiple inheritance straight away with help of virtual keyword when needed

Because of point 3 interface concept was never formally introduced in C++. Still one can have a flexibility to do that.

Besides this you can refer Bjarne's FAQ on this topic.

ValueError: math domain error

Your code is doing a log of a number that is less than or equal to zero. That's mathematically undefined, so Python's log function raises an exception. Here's an example:

>>> from math import log
>>> log(-1)
Traceback (most recent call last):
  File "<pyshell#59>", line 1, in <module>
    log(-1)
ValueError: math domain error

Without knowing what your newtonRaphson2 function does, I'm not sure I can guess where the invalid x[2] value is coming from, but hopefully this will lead you on the right track.

Getting the location from an IP address

You could download a free GeoIP database and lookup the IP address locally, or you could use a third party service and perform a remote lookup. This is the simpler option, as it requires no setup, but it does introduce additional latency.

One third party service you could use is mine, http://ipinfo.io. They provide hostname, geolocation, network owner and additional information, eg:

$ curl ipinfo.io/8.8.8.8
{
  "ip": "8.8.8.8",
  "hostname": "google-public-dns-a.google.com",
  "loc": "37.385999999999996,-122.0838",
  "org": "AS15169 Google Inc.",
  "city": "Mountain View",
  "region": "CA",
  "country": "US",
  "phone": 650
}

Here's a PHP example:

$ip = $_SERVER['REMOTE_ADDR'];
$details = json_decode(file_get_contents("http://ipinfo.io/{$ip}/json"));
echo $details->city; // -> "Mountain View"

You can also use it client-side. Here's a simple jQuery example:

_x000D_
_x000D_
$.get("https://ipinfo.io/json", function (response) {_x000D_
    $("#ip").html("IP: " + response.ip);_x000D_
    $("#address").html("Location: " + response.city + ", " + response.region);_x000D_
    $("#details").html(JSON.stringify(response, null, 4));_x000D_
}, "jsonp");
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>_x000D_
<h3>Client side IP geolocation using <a href="http://ipinfo.io">ipinfo.io</a></h3>_x000D_
_x000D_
<hr/>_x000D_
<div id="ip"></div>_x000D_
<div id="address"></div>_x000D_
<hr/>Full response: <pre id="details"></pre>
_x000D_
_x000D_
_x000D_

How do I create executable Java program?

Jexecutable can create Windows exe for Java programs. It embeds the jars into exe file and you can run it like a Windows program.

How to establish ssh key pair when "Host key verification failed"

Also sometimes there is situation when you are working on serial console, then checking above command in verbose mode -v will show you /dev/tty does not exists, while it does.

In above case just remove /dev/tty and create a symlink of /dev/ttyS0 to /dev/tty.

Finish all activities at a time

For API 16+, use

finishAffinity();

For lower, use

ActivityCompat.finishAffinity(YourActivity.this)

SQL Server format decimal places with commas

Thankfully(?), in SQL Server 2012+, you can now use FORMAT() to achieve this:

FORMAT(@s,'#,0.0000')


In prior versions, at the risk of looking real ugly

[Query]:

declare @s decimal(18,10);
set @s = 1234.1234567;
select replace(convert(varchar,cast(floor(@s) as money),1),'.00',
    '.'+right(cast(@s * 10000 +10000.5 as int),4))

In the first part, we use MONEY->VARCHAR to produce the commas, but FLOOR() is used to ensure the decimals go to .00. This is easily identifiable and replaced with the 4 digits after the decimal place using a mixture of shifting (*10000) and CAST as INT (truncation) to derive the digits.

[Results]:

|   COLUMN_0 |
--------------
| 1,234.1235 |

But unless you have to deliver business reports using SQL Server Management Studio or SQLCMD, this is NEVER the correct solution, even if it can be done. Any front-end or reporting environment has proper functions to handle display formatting.

How to use format() on a moment.js duration?

If you use Angular >2, I made a Pipe inspired by @hai-alaluf answer.

import {Pipe, PipeTransform} from "@angular/core";

@Pipe({
  name: "duration",
})

export class DurationPipe implements PipeTransform {

  public transform(value: any, args?: any): any {

    // secs to ms
    value = value * 1000;
    const days = Math.floor(value / 86400000);
    value = value % 86400000;
    const hours = Math.floor(value / 3600000);
    value = value % 3600000;
    const minutes = Math.floor(value / 60000);
    value = value % 60000;
    const seconds = Math.floor(value / 1000);
    return (days ? days + " days " : "") +
      (hours ? hours + " hours " : "") +
      (minutes ? minutes + " minutes " : "") +
      (seconds ? seconds + " seconds " : "") +
      (!days && !hours && !minutes && !seconds ? 0 : "");
  }
}

Encrypt and decrypt a string in C#?

I have an open source project called X509Crypto that leverages certificates to encrypt and decrypt strings. It's very easy to use. Here is an example for how to use it:

1. Use the X509Crypto Commandline Interface (CLI) to generate a new encryption certificate and key pair

>x509crypto.exe
X509Crypto> makecert -context user -keysize medium -alias myvault

Certificate with thumbprint B31FE7E7AE5229F8186782742CF579197FA859FD was added to X509Alias "myvault" in the user X509Context

X509Crypto>

2. Use the Encrypt CLI command to add a secret to your new X509Alias

X509Crypto> encrypt -text -alias myvault -context user -secret apikey -in "80EAF03248965AC2B78090"

Secret apikey has been added to X509Alias myvault in the user X509Context

X509Crypto>

3. Reference the secret in your program

Once you have an X509Alias established with your secret(s) added, it is trivial to retreive them in your program with the Org.X509Crypto nuget package installed:

using Org.X509Crypto;

namespace SampleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var Alias = new X509Alias(@"myvault", X509Context.UserReadOnly);
            var apiKey = Alias.RecoverSecret(@"apikey");
        }
    }
}

Removing empty lines in Notepad++

It's very Simple ## No need of any extra plugin

You know what, now Notepad ++ has inbuilt functionality to do so...

  1. Open EDIT Menu by: Alt+E > Press down Arrow > Line Operations > Remove Empty Lines

Remove_Emplty_Lines

  1. Other Option is to use Replace press: ctrl + H

Find : \r\n\r\n

Replcate with : \r\n

Remove_by_Replace

Python : Trying to POST form using requests

You can use the Session object

import requests
headers = {'User-Agent': 'Mozilla/5.0'}
payload = {'username':'niceusername','password':'123456'}

session = requests.Session()
session.post('https://admin.example.com/login.php',headers=headers,data=payload)
# the session instance holds the cookie. So use it to get/post later.
# e.g. session.get('https://example.com/profile')

Uncaught TypeError: Object #<Object> has no method 'movingBoxes'

Please keep in mind that only a few elements can be self-closing, most others have to be closed through adding an explicit end tag. In the above case, the first script tag was not closed properly, the end script tag of the second script then closed the script section, causing only the first script to be loaded as external script source and ignoring the second script.

More info about which tags can be self-closed, have a look at the W3C drafts for HTML5 (although the definition was no different in earlier HTML-versions):

http://www.w3.org/TR/html5/syntax.html#end-tags (8.1.2.1, Point 6)

Exporting result of select statement to CSV format in DB2

This is how you can do it from DB2 client.

  1. Open the Command Editor and Run the select Query in the Commands Tab.

  2. Open the corresponding Query Results Tab

  3. Then from Menu --> Selected --> Export

Android - drawable with rounded corners at the top only

Create roung_top_corners.xml on drawable and copy the below code

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
<corners
    android:topLeftRadius="22dp"
    android:topRightRadius="22dp"
    android:bottomLeftRadius="0dp"
    android:bottomRightRadius="0dp"
    />
<gradient
    android:angle="180"
    android:startColor="#1d2b32"
    android:centerColor="#465059"
    android:endColor="#687079"
    android:type="linear" />
<padding
    android:left="0dp"
    android:top="0dp"
    android:right="0dp"
    android:bottom="0dp"
    />
<size
    android:width="270dp"
    android:height="60dp"
    /></shape>

CSS for the "down arrow" on a <select> element?

You would need to create your own dropdown using hidden divs and a hidden input element to record which option was "selected". My guess is that @Jan Hancic's link he posted is probably what you're looking for.

Right query to get the current number of connections in a PostgreSQL DB

Aggregation of all postgres sessions per their status (how many are idle, how many doing something...)

select state, count(*) from pg_stat_activity  where pid <> pg_backend_pid() group by 1 order by 1;

Best font for coding

I like Consolas a lot. This top-10 list is a good resource for others. It includes examples and descriptions.

DataGridView.Clear()

try setting RowCount to 0(allowuserstorows should be false), along with calling clear

Understanding the grid classes ( col-sm-# and col-lg-# ) in Bootstrap 3

"If I want two columns for anything over 768px, should I apply both classes?"

This should be as simple as:

<div class="row">
      <div class="col-sm-6"></div>
      <div class="col-sm-6"></div>    
</div>

No need to add the col-lg-6 too.

Demo: http://www.bootply.com/73119

How to remove the Flutter debug banner?

You can give simply hide this by giving a boolean parameter-----> debugShowCheckedModeBanner: false,

void main() {
  Bloc.observer = SimpleBlocDelegate();

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Prescription Writing Software',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        scaffoldBackgroundColor: Colors.white,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: SplashScreen(),
    );
  }
}

How do I get AWS_ACCESS_KEY_ID for Amazon?

It is very dangerous to create an access_key_id in "My Account ==> Security Credentials". Because the key has all authority. Please create "IAM" user and attach only some policies you need.

When and how should I use a ThreadLocal variable?

when?

When an object is not thread-safe, instead of synchronization which hampers the scalability, give one object to every thread and keep it thread scope, which is ThreadLocal. One of most often used but not thread-safe objects are database Connection and JMSConnection.

How ?

One example is Spring framework uses ThreadLocal heavily for managing transactions behind the scenes by keeping these connection objects in ThreadLocal variables. At high level, when a transaction is started it gets the connection ( and disables the auto commit ) and keeps it in ThreadLocal. on further db calls it uses same connection to communicate with db. At the end, it takes the connection from ThreadLocal and commits ( or rollback ) the transaction and releases the connection.

I think log4j also uses ThreadLocal for maintaining MDC.

Why does .NET foreach loop throw NullRefException when collection is null?

A foreach loop calls the GetEnumerator method.
If the collection is null, this method call results in a NullReferenceException.

It is bad practice to return a null collection; your methods should return an empty collection instead.

Why is Android Studio reporting "URI is not registered"?

Started getting this again, What actually works now is to add some rubbish inside build.gradle. Then try and sync. When it fails remove the rubbish and re-sync. After indexing, it works.

Error in Eclipse: "The project cannot be built until build path errors are resolved"

If you can't find the build path error, sometimes menu Project ? Clean... works like a charm.

How to reset settings in Visual Studio Code?

Steps to reset on Windows:

  • Press 'Windows-Key"+R , and enter %APPDATA%\Code\User

    enter image description here

    And delete 'setting.json' at this location.

  • Press 'Windows-Key"+R , and enter %USERPROFILE%.vscode\extensions

    enter image description here

    And delete all the extensions there.

EDIT

After two vote downs added images to make it more clear :)

How to set environment variables in PyCharm?

I was able to figure out this using a PyCharm plugin called EnvFile. This plugin, basically allows setting environment variables to run configurations from one or multiple files.

The installation is pretty simple:

Preferences > Plugins > Browse repositories... > Search for "Env File" > Install Plugin.

Then, I created a file, in my project root, called environment.env which contains:

DATABASE_URL=postgres://127.0.0.1:5432/my_db_name
DEBUG=1

Then I went to Run->Edit Configurations, and I followed the steps in the next image:

Set Environment Variables

In 3, I chose the file environment.env, and then I could just click the play button in PyCharm, and everything worked like a charm.

Remove legend ggplot 2.2

There might be another solution to this:
Your code was:

geom_point(aes(..., show.legend = FALSE))

You can specify the show.legend parameter after the aes call:

geom_point(aes(...), show.legend = FALSE)

then the corresponding legend should disappear

import sun.misc.BASE64Encoder results in error compiled in Eclipse

I am using unix system.

In eclipse project-> Properties -> Java Compiler -> Errors/Warning -> Forbidden Access(access rule) -> Turn it to warning/Ignore(Previously it was set to Error).

Groovy - Convert object to JSON string

You can use JsonBuilder for that.

Example Code:

import groovy.json.JsonBuilder

class Person {
    String name
    String address
}

def o = new Person( name: 'John Doe', address: 'Texas' )

println new JsonBuilder( o ).toPrettyString()

Load HTML file into WebView

The easiest way would probably be to put your web resources into the assets folder then call:

webView.loadUrl("file:///android_asset/filename.html");

For Complete Communication between Java and Webview See This

Update: The assets folder is usually the following folder: <project>/src/main/assets This can be changed in the asset folder configuration setting in your <app>.iml file as:

<option name=”ASSETS_FOLDER_RELATIVE_PATH” value=”/src/main/assets” /> See Article Where to place the assets folder in Android Studio

What is a 'NoneType' object?

In Python, to represent the absence of a value, you can use the None value types.NoneType.None

Set specific precision of a BigDecimal

Try this code ...

    Integer perc = 5;
    BigDecimal spread = BigDecimal.ZERO; 
    BigDecimal perc = spread.setScale(perc,BigDecimal.ROUND_HALF_UP);
    System.out.println(perc);

Result: 0.00000

if (boolean == false) vs. if (!boolean)

The first form, when used with an API that returns Boolean and compared against Boolean.FALSE, will never throw a NullPointerException.

The second form, when used with the java.util.Map interface, also, will never throw a NullPointerException because it returns a boolean and not a Boolean.

If you aren't concerned about consistent coding idioms, then you can pick the one you like, and in this concrete case it really doesn't matter. If you do care about consistent coding, then consider what you want to do when you check a Boolean that may be NULL.

Create a directory if it doesn't exist

#include <experimental/filesystem> // or #include <filesystem> for C++17 and up
    
namespace fs = std::experimental::filesystem;


if (!fs::is_directory("src") || !fs::exists("src")) { // Check if src folder exists
    fs::create_directory("src"); // create src folder
}

iOS 7 status bar overlapping UI

We can also check this within our js files

if (parseFloat(window.device.version) >= 7.0) {

    $("body").addClass("ios7");
}

In .css file define a class for this

 .ios7 .ui-page, .ios7 .ui-header, .ios7 .ui-pane {
     margin-top: 17px !important;
  }

Inserting a string into a list without getting split into characters

To add to the end of the list:

list.append('foo')

To insert at the beginning:

list.insert(0, 'foo')

jQuery vs. javascript?

Jquery like any other good JavaScript frameworks supplies you with functionality independent of browser platform wrapping all the intricacies, which you may not care about or don't want to care about.

I think using a framework is better instead of using pure JavaScript and doing all the stuff from scratch, unless you usage is very limited.

I definitely recommend JQuery!

Thanks

Git submodule head 'reference is not a tree' error

I got this error when I did:

$ git submodule update --init --depth 1

but the commit in the parent project was pointing at an earlier commit.

Deleting the submodule folder and running:

$ git submodule update --init

did NOT solve the problem. I deleted the repo and tried again without the depth flag and it worked.

This error happens in Ubuntu 16.04 git 2.7.4, but not on Ubuntu 18.04 git 2.17, TODO find exact fixing commit or version.

Android "gps requires ACCESS_FINE_LOCATION" error, even though my manifest file contains this

CAUSE: "Beginning in Android 6.0 (API level 23), users grant permissions to apps while the app is running, not when they install the app." In this case, "ACCESS_FINE_LOCATION" is a "dangerous permission and for that reason, you get this 'java.lang.SecurityException: "gps" location provider requires ACCESS_FINE_LOCATION permission.' error (https://developer.android.com/training/permissions/requesting.html).

SOLUTION: Implementing the code provided at https://developer.android.com/training/permissions/requesting.html under the "Request the permissions you need" and "Handle the permissions request response" headings.

How To Set Text In An EditText

String string="this is a text";
editText.setText(string)

I have found String to be a useful Indirect Subclass of CharSequence

http://developer.android.com/reference/android/widget/TextView.html find setText(CharSequence text)

http://developer.android.com/reference/java/lang/CharSequence.html

How to find common elements from multiple vectors?

There might be a cleverer way to go about this, but

intersect(intersect(a,b),c)

will do the job.

EDIT: More cleverly, and more conveniently if you have a lot of arguments:

Reduce(intersect, list(a,b,c))

How to use Git Revert

I reverted back a few commits by running 'git revert commit id' such as:

git revert b2cb7c248d416409f8eb42b561cbff91b0601712

Then i was prompted to commit the revert (just as you would when running 'git commit'). My default terminal program is Vim so i ran:

:wq 

Finally i pushed the change to the repository with:

git push

Adding JPanel to JFrame

Instead of having your Test2 class contain a JPanel, you should have it subclass JPanel:

public class Test2 extends JPanel {

Test2(){

...

}

More details:

JPanel is a subclass of Component, so any method that takes a Component as an argument can also take a JPanel as an argument.

Older versions didn't let you add directly to a JFrame; you had to use JFrame.getContentPane().add(Component). If you're using an older version, this might also be an issue. Newer versions of Java do let you call JFrame.add(Component) directly.

Select element based on multiple classes

Chain selectors are not limited just to classes, you can do it for both classes and ids.

Classes

.classA.classB {
/*style here*/
}

Class & Id

.classA#idB {
/*style here*/
}

Id & Id

#idA#idB {
/*style here*/
}

All good current browsers support this except IE 6, it selects based on the last selector in the list. So ".classA.classB" will select based on just ".classB".

For your case

li.left.ui-class-selector {
/*style here*/
}

or

.left.ui-class-selector {
/*style here*/
}

Solution to "subquery returns more than 1 row" error

You can use in():

select * 
from table
where id in (multiple row query)

or use a join:

select distinct t.* 
from source_of_id_table s
join table t on t.id = s.t_id
where <conditions for source_of_id_table>

The join is never a worse choice for performance, and depending on the exact situation and the database you're using, can give much better performance.

File Upload with Angular Material

html:
    <div class="upload">
        <span>upload image</span>
        <input
          #Image
          type="file"
          (change)="handleFileInput($event.target.files)"
          accept=".jpg,.svg,.png,.jpeg"
        />
        <img
          width="100%"
          height="100%"
          *ngIf="imageUrl"
          [src]="imageUrl"
          class="image"
        />
    </div>

app.component.ts

export class AppComponent {
  options = [{ value: "This is value 1", checked: true }];
  statuses = ["control"];

  // name = "Angular";//
  fileToUpload: any;
  imageUrl: any;
  handleFileInput(file: FileList) {
    this.fileToUpload = file.item(0);

    //Show image preview
    let reader = new FileReader();
    reader.onload = (event: any) => {
      this.imageUrl = event.target.result;
    };
    reader.readAsDataURL(this.fileToUpload);
  }
}

Alternative to itoa() for converting integer to string C++?

Most of the above suggestions technically aren't C++, they're C solutions.

Look into the use of std::stringstream.

RegEx to extract all matches from string using RegExp.exec

If you have ES9

(Meaning if your system: Chrome, Node.js, Firefox, etc supports Ecmascript 2019 or later)

Use the new yourString.matchAll( /your-regex/ ).

If you don't have ES9

If you have an older system, here's a function for easy copy and pasting

function findAll(regexPattern, sourceString) {
    let output = []
    let match
    // make sure the pattern has the global flag
    let regexPatternWithGlobal = RegExp(regexPattern,[...new Set("g"+regexPattern.flags)].join(""))
    while (match = regexPatternWithGlobal.exec(sourceString)) {
        // get rid of the string copy
        delete match.input
        // store the match data
        output.push(match)
    } 
    return output
}

example usage:

console.log(   findAll(/blah/g,'blah1 blah2')   ) 

outputs:

[ [ 'blah', index: 0 ], [ 'blah', index: 6 ] ]

Makefile - missing separator

You need to precede the lines starting with gcc and rm with a hard tab. Commands in make rules are required to start with a tab (unless they follow a semicolon on the same line). The result should look like this:

PROG = semsearch
all: $(PROG)
%: %.c
        gcc -o $@ $< -lpthread

clean:
        rm $(PROG)

Note that some editors may be configured to insert a sequence of spaces instead of a hard tab. If there are spaces at the start of these lines you'll also see the "missing separator" error. If you do have problems inserting hard tabs, use the semicolon way:

PROG = semsearch
all: $(PROG)
%: %.c ; gcc -o $@ $< -lpthread

clean: ; rm $(PROG)

how to create a Java Date object of midnight today and midnight tomorrow?

Date todayMidnightUTC = java.sql.Date.valueOf(LocalDate.now());
Date tomorrowMidnightUTC = java.sql.Date.valueOf(LocalDate.now().plusDays(1));
Date anyMidnightLocal = java.sql.Date.valueOf(LocalDate.from(dateTime.toInstant().atZone(ZoneId.systemDefault())));

But beware that java.sql.Date.toInstant() always throws UnsupportedOperationException.

Via LocalDate to java.util.Date and vice versa simpliest conversion?

Match the path of a URL, minus the filename extension

This general URL match allows you to select parts of a URL:

if (preg_match('/\\b(?P<protocol>https?|ftp):\/\/(?P<domain>[-A-Z0-9.]+)(?P<file>\/[-A-Z0-9+&@#\/%=~_|!:,.;]*)?(?P<parameters>\\?[-A-Z0-9+&@#\/%=~_|!:,.;]*)?/i', $subject, $regs)) {
    $result = $regs['file'];
    //or you can append the $regs['parameters'] too
} else {
    $result = "";
}

Reset the Value of a Select Box

This works for me:

$('select').prop('selectedIndex', 0);

FIDDLE

SQL WHERE condition is not equal to?

WHERE id <> 2 should work fine...Is that what you are after?

How to use SQL Order By statement to sort results case insensitive?

You can also do ORDER BY TITLE COLLATE NOCASE.

Edit: If you need to specify ASC or DESC, add this after NOCASE like

ORDER BY TITLE COLLATE NOCASE ASC

or

ORDER BY TITLE COLLATE NOCASE DESC

Apache error: _default_ virtualhost overlap on port 443

To resolve the issue on a Debian/Ubuntu system modify the /etc/apache2/ports.conf settings file by adding NameVirtualHost *:443 to it. My ports.conf is the following at the moment:

# /etc/apache/ports.conf
# If you just change the port or add more ports here, you will likely also
# have to change the VirtualHost statement in
# /etc/apache2/sites-enabled/000-default
# This is also true if you have upgraded from before 2.2.9-3 (i.e. from
# Debian etch). See /usr/share/doc/apache2.2-common/NEWS.Debian.gz and
# README.Debian.gz

NameVirtualHost *:80
Listen 80

<IfModule mod_ssl.c>
    # If you add NameVirtualHost *:443 here, you will also have to change
    # the VirtualHost statement in /etc/apache2/sites-available/default-ssl
    # to <VirtualHost *:443>
    # Server Name Indication for SSL named virtual hosts is currently not
    # supported by MSIE on Windows XP.

    NameVirtualHost *:443

    Listen 443
</IfModule>

<IfModule mod_gnutls.c>
    NameVirtualHost *:443
    Listen 443
</IfModule>

Furthermore ensure that 'sites-available/default-ssl' is not enabled, type a2dissite default-ssl to disable the site. While you're at it type a2dissite by itself to get a list and see if there is any other site settings that you have enabled that might be mapping onto port 443.

How to stop process from .BAT file?

taskkill /F /IM notepad.exe this is the best way to kill the task from task manager.

Split string, convert ToList<int>() in one line

You can use new C# 6.0 Language Features:

  • replace delegate (s) => { return Convert.ToInt32(s); } with corresponding method group Convert.ToInt32
  • replace redundant constructor call: new Converter<string, int>(Convert.ToInt32) with: Convert.ToInt32

The result will be:

var intList = new List<int>(Array.ConvertAll(sNumbers.Split(','), Convert.ToInt32));

How to uninstall downloaded Xcode simulator?

NOTE: This will only remove a device configuration from the Xcode devices list. To remove the simulator files from your hard drive see the previous answer.

For Xcode 7 just use Window \ Devices menu in Xcode:

Devices menu

Then select emulator to delete in the list on the left side and right click on it. Here is Delete option: enter image description here

That's all.

How to style child components from parent component's CSS file?

As of today (Angular 9), Angular uses a Shadow DOM to display the components as custom HTML elements. One elegant way to style those custom elements might be using custom CSS variables. Here is a generic example:

_x000D_
_x000D_
class ChildElement extends HTMLElement {_x000D_
  constructor() {_x000D_
    super();_x000D_
    _x000D_
    var shadow = this.attachShadow({mode: 'open'});_x000D_
    var wrapper = document.createElement('div');_x000D_
    wrapper.setAttribute('class', 'wrapper');_x000D_
    _x000D_
    // Create some CSS to apply to the shadow dom_x000D_
    var style = document.createElement('style');_x000D_
    _x000D_
    style.textContent = `_x000D_
    _x000D_
      /* Here we define the default value for the variable --background-clr */_x000D_
      :host {_x000D_
        --background-clr: green;_x000D_
      }_x000D_
      _x000D_
      .wrapper {_x000D_
        width: 100px;_x000D_
        height: 100px;_x000D_
        background-color: var(--background-clr);_x000D_
        border: 1px solid red;_x000D_
      }_x000D_
    `;_x000D_
    _x000D_
    shadow.appendChild(style);_x000D_
    shadow.appendChild(wrapper);_x000D_
  }_x000D_
}_x000D_
_x000D_
// Define the new element_x000D_
customElements.define('child-element', ChildElement);
_x000D_
/* CSS CODE */_x000D_
_x000D_
/* This element is referred as :host from the point of view of the custom element. Commenting out this CSS will result in the background to be green, as defined in the custom element */_x000D_
_x000D_
child-element {_x000D_
  --background-clr: yellow; _x000D_
}
_x000D_
<div>_x000D_
  <child-element></child-element>_x000D_
</div>
_x000D_
_x000D_
_x000D_

As we can see from the above code, we create a custom element, just like Angular would do for us with every component, and then we override the variable responsible for the background color within the shadow root of the custom element, from the global scope.

In an Angular app, this might be something like:

parent.component.scss

child-element {
  --background-clr: yellow;
}

child-element.component.scss

:host {
  --background-clr: green;
}

.wrapper {
  width: 100px;
  height: 100px;
  background-color: var(--background-clr);
  border: 1px solid red;
}

Why would Oracle.ManagedDataAccess not work when Oracle.DataAccess does?

To avoid all the Oracle mess of not knowing where it is looking for the TNSNAMES.ORA (I have the added confusion of multiple Oracle versions and 32/64 bit), you can copy the setting from your existing TNSNAMES.ORA to your own config file and use that for your connection.
Say you're happy with the 'DSDSDS' reference in TNSNAMES.ORA which maps to something like:

DSDSDS=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(Host=DSDSDSHost)(Port=4521)))(CONNECT_DATA=(SERVICE_NAME=DSDSDSService)))

You can take the text after the first '=' and use that wherever you are using 'DSDSDS' and it won't need to find TNSNAMES.ORA to know how to connect.
Now your connection string would look like this:
string connectionString = "Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(Host=DSDSDSHost)(Port=4521)))(CONNECT_DATA=(SERVICE_NAME=DSDSDSService)));User Id=UNUNUN;Password=PWPWPW;";

Get current time in hours and minutes

Provide a format string:

date +"%H:%M"

Running man date will give all the format options

%a     locale's abbreviated weekday name (e.g., Sun)
%A     locale's full weekday name (e.g., Sunday)
%b     locale's abbreviated month name (e.g., Jan)
%B     locale's full month name (e.g., January)
%c     locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
%C     century; like %Y, except omit last two digits (e.g., 20)
%d     day of month (e.g., 01)
%D     date; same as %m/%d/%y
%e     day of month, space padded; same as %_d
%F     full date; same as %Y-%m-%d
%g     last two digits of year of ISO week number (see %G)
%G     year of ISO week number (see %V); normally useful only with %V
%h     same as %b
%H     hour (00..23)
%I     hour (01..12)
%j     day of year (001..366)
%k     hour, space padded ( 0..23); same as %_H
%l     hour, space padded ( 1..12); same as %_I
%m     month (01..12)
%M     minute (00..59)
%n     a newline
%N     nanoseconds (000000000..999999999)
%p     locale's equivalent of either AM or PM; blank if not known
%P     like %p, but lower case
%r     locale's 12-hour clock time (e.g., 11:11:04 PM)
%R     24-hour hour and minute; same as %H:%M
%s     seconds since 1970-01-01 00:00:00 UTC
%S     second (00..60)
%t     a tab
%T     time; same as %H:%M:%S
%u     day of week (1..7); 1 is Monday
%U     week number of year, with Sunday as first day of week (00..53)
%V     ISO week number, with Monday as first day of week (01..53)
%w     day of week (0..6); 0 is Sunday
%W     week number of year, with Monday as first day of week (00..53)
%x     locale's date representation (e.g., 12/31/99)
%X     locale's time representation (e.g., 23:13:48)
%y     last two digits of year (00..99)
%Y     year
%z     +hhmm numeric time zone (e.g., -0400)
%:z    +hh:mm numeric time zone (e.g., -04:00)
%::z   +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z     alphabetic time zone abbreviation (e.g., EDT)

Dynamically replace img src attribute with jQuery

This is what you wanna do:

var oldSrc = 'http://example.com/smith.gif';
var newSrc = 'http://example.com/johnson.gif';
$('img[src="' + oldSrc + '"]').attr('src', newSrc);

Expression ___ has changed after it was checked

You can also create a timer using the rxjs Observable.timer function, and then update the message in your subscription:                    

Observable.timer(1).subscribe(()=> this.updateMessage());

CSS Display an Image Resized and Cropped

img {
    position: absolute;
    clip: rect(0px,60px,200px,0px);
} 

How to display a database table on to the table in the JSP page

The problem here is very simple. If you want to display value in JSP, you have to use <%= %> tag instead of <% %>, here is the solved code:

<tr> <td><%=rs.getInt("ID") %></td> <td><%=rs.getString("NAME") %></td> <td><%=rs.getString("SKILL") %></td> </tr>

Why does DEBUG=False setting make my django Static Files Access fail?

Just open your project urls.py, then find this if statement.

if settings.DEBUG:
    urlpatterns += patterns(
        'django.views.static',
        (r'^media/(?P<path>.*)','serve',{'document_root': settings.MEDIA_ROOT}), )

You can change settings.DEBUG on True and it will work always. But if your project is a something serious then you should to think about other solutions mentioned above.

if True:
    urlpatterns += patterns(
        'django.views.static',
        (r'^media/(?P<path>.*)','serve',{'document_root': settings.MEDIA_ROOT}), )

In django 1.10 you can write so:

urlpatterns += [ url(r'^media/(?P<path>.*)$', serve, { 'document_root': settings.MEDIA_ROOT, }), url(r'^static/(?P<path>.*)$', serve, { 'document_root': settings.STATIC_ROOT }), ]

What's the difference between ConcurrentHashMap and Collections.synchronizedMap(Map)?

For your needs, use ConcurrentHashMap. It allows concurrent modification of the Map from several threads without the need to block them. Collections.synchronizedMap(map) creates a blocking Map which will degrade performance, albeit ensure consistency (if used properly).

Use the second option if you need to ensure data consistency, and each thread needs to have an up-to-date view of the map. Use the first if performance is critical, and each thread only inserts data to the map, with reads happening less frequently.

If statement for strings in python?

Python is case sensitive and needs proper indentation. You need to use lowercase "if", indent your conditions properly and the code has a bug. proceed will evaluate to y

If a DOM Element is removed, are its listeners also removed from memory?

Regarding jQuery, the following common methods will also remove other constructs such as data and event handlers:

remove()

In addition to the elements themselves, all bound events and jQuery data associated with the elements are removed.

empty()

To avoid memory leaks, jQuery removes other constructs such as data and event handlers from the child elements before removing the elements themselves.

html()

Additionally, jQuery removes other constructs such as data and event handlers from child elements before replacing those elements with the new content.

Can we have multiple <tbody> in same <table>?

EDIT: The caption tag belongs to table and thus should only exist once. Do not associate a caption with each tbody element like I did:

<table>
    <caption>First Half of Table (British Dinner)</caption>
    <tbody>
        <tr><th>1</th><td>Fish</td></tr>
        <tr><th>2</th><td>Chips</td></tr>
        <tr><th>3</th><td>Pease</td></tr>
        <tr><th>4</th><td>Gravy</td></tr>
    </tbody>
    <caption>Second Half of Table (Italian Dinner)</caption>
    <tbody>
        <tr><th>5</th><td>Pizza</td></tr>
        <tr><th>6</th><td>Salad</td></tr>
        <tr><th>7</th><td>Oil</td></tr>
        <tr><th>8</th><td>Bread</td></tr>
    </tbody>
</table>

BAD EXAMPLE ABOVE: DO NOT COPY

The above example does not render as you would expect because writing like this indicates a misunderstanding of the caption tag. You would need lots of CSS hacks to make it render correctly because you would be going against standards.

I searched for W3Cs standards on the caption tag but could not find an explicit rule that states there must be only one caption element per table but that is in fact the case.

Hide password with "•••••••" in a textField

For SwiftUI, try

TextField ("Email", text: $email)
    .textFieldStyle(RoundedBorderTextFieldStyle()).padding()
SecureField ("Password", text: $password)
    .textFieldStyle(RoundedBorderTextFieldStyle()).padding()

Is it possible to have SSL certificate for IP address, not domain name?

The answer is yes. In short, it is a subject alternative name (SAN) certificate that contains IPs where you would typically see DNS entries. The certificate type is not limited to Public IPs - that restriction is only imposed by a signing authority rather than the technology. I just wanted to clarify that point. I suspect you really just want to get rid of that pesky insecure prompt on your internal websites and devices without the cost and hassle of giving them DNS names then paying for a CA to issue a cert every year or two. You should NOT be trying to convince the world that your IP address is a reputable website and folks should feel comfortable providing their payment information. Now that we have established why no reputable organization wants to issue this type of certificate, lets just do it ourselves with a self signed SAN certificate. Internally I have a trusted certificate that is deployed to all of our hosts, then I sign this type of certificate with it and all devices become trusted. Doing that here is beyond the scope of the question but I think it relevant to the discussion as the question and solution go hand in hand. To be concise, here is how to generate an individual self signed SAN certificate with IP addresses. Expand the IP list to include your entire subnet and use one cert for everything.

#!/bin/bash
#using: OpenSSL 1.1.1c FIPS  28 May 2019 / CentOS Linux release 8.2.2004

C=US ; ST=Confusion ; L=Anywhere ; O=Private\ Subnet ; [email protected]
BITS=2048
CN=RFC1918
DOM=company.com
SUBJ="/C=$C/ST=$ST/L=$L/O=$O/CN=$CN.$DOM"

openssl genrsa -out ip.key $BITS

SAN='\n[SAN]\nsubjectAltName=IP:192.168.1.0,IP:192.168.1.1,IP:192.168.1.2,IP:192.168.1.3,IP:192.168.1.4,IP:192.168.1.5,IP:192.168.1.6,IP:192.168.1.7,IP:192.168.1.8,IP:192.168.1.9,IP:192.168.1.10'

cp /etc/pki/tls/openssl.cnf /tmp/openssl.cnf
echo -e "$SAN" >> /tmp/openssl.cnf

openssl req -subj "$SUBJ" -new -x509 -days 10950 \
    -key ip.key -out ip.crt -batch \
    -set_serial 168933982 \
    -config /tmp/openssl.cnf \
    -extensions SAN

openssl x509 -in ip.crt -noout -text

XPath using starts-with function

Use:

/*/ITEM[starts-with(REVENUE_YEAR,'2552')]/REGION

Note: Unless your host language can't handle element instance as result, do not use text nodes specially in mixed content data model. Do not start expressions with // operator when the schema is well known.

This Row already belongs to another table error when trying to add rows?

you can give some id to the columns and name it uniquely.

Convert javascript object or array to json for ajax data

You can use JSON.stringify(object) with an object and I just wrote a function that'll recursively convert an array to an object, like this JSON.stringify(convArrToObj(array)), which is the following code (more detail can be found on this answer):

// Convert array to object
var convArrToObj = function(array){
    var thisEleObj = new Object();
    if(typeof array == "object"){
        for(var i in array){
            var thisEle = convArrToObj(array[i]);
            thisEleObj[i] = thisEle;
        }
    }else {
        thisEleObj = array;
    }
    return thisEleObj;
}

To make it more generic, you can override the JSON.stringify function and you won't have to worry about it again, to do this, just paste this at the top of your page:

// Modify JSON.stringify to allow recursive and single-level arrays
(function(){
    // Convert array to object
    var convArrToObj = function(array){
        var thisEleObj = new Object();
        if(typeof array == "object"){
            for(var i in array){
                var thisEle = convArrToObj(array[i]);
                thisEleObj[i] = thisEle;
            }
        }else {
            thisEleObj = array;
        }
        return thisEleObj;
    };
    var oldJSONStringify = JSON.stringify;
    JSON.stringify = function(input){
        return oldJSONStringify(convArrToObj(input));
    };
})();

And now JSON.stringify will accept arrays or objects! (link to jsFiddle with example)


Edit:

Here's another version that's a tad bit more efficient, although it may or may not be less reliable (not sure -- it depends on if JSON.stringify(array) always returns [], which I don't see much reason why it wouldn't, so this function should be better as it does a little less work when you use JSON.stringify with an object):

(function(){
    // Convert array to object
    var convArrToObj = function(array){
        var thisEleObj = new Object();
        if(typeof array == "object"){
            for(var i in array){
                var thisEle = convArrToObj(array[i]);
                thisEleObj[i] = thisEle;
            }
        }else {
            thisEleObj = array;
        }
        return thisEleObj;
    };
    var oldJSONStringify = JSON.stringify;
    JSON.stringify = function(input){
        if(oldJSONStringify(input) == '[]')
            return oldJSONStringify(convArrToObj(input));
        else
            return oldJSONStringify(input);
    };
})();

jsFiddle with example here

js Performance test here, via jsPerf

c++ array assignment of multiple values

There is a difference between initialization and assignment. What you want to do is not initialization, but assignment. But such assignment to array is not possible in C++.

Here is what you can do:

#include <algorithm>

int array [] = {1,3,34,5,6};
int newarr [] = {34,2,4,5,6};
std::copy(newarr, newarr + 5, array);

However, in C++0x, you can do this:

std::vector<int> array = {1,3,34,5,6};
array = {34,2,4,5,6};

Of course, if you choose to use std::vector instead of raw array.

What is HTTP "Host" header?

The Host Header tells the webserver which virtual host to use (if set up). You can even have the same virtual host using several aliases (= domains and wildcard-domains). In this case, you still have the possibility to read that header manually in your web app if you want to provide different behavior based on different domains addressed. This is possible because in your webserver you can (and if I'm not mistaken you must) set up one vhost to be the default host. This default vhost is used whenever the host header does not match any of the configured virtual hosts.

That means: You get it right, although saying "multiple hosts" may be somewhat misleading: The host (the addressed machine) is the same, what really gets resolved to the IP address are different domain names (including subdomains) that are also referred to as hostnames (but not hosts!).


Although not part of the question, a fun fact: This specification led to problems with SSL in early days because the web server has to deliver the certificate that corresponds to the domain the client has addressed. However, in order to know what certificate to use, the webserver should have known the addressed hostname in advance. But because the client sends that information only over the encrypted channel (which means: after the certificate has already been sent), the server had to assume you browsed the default host. That meant one ssl-secured domain per IP address / port-combination.

This has been overcome with Server Name Indication; however, that again breaks some privacy, as the server name is now transferred in plain text again, so every man-in-the-middle would see which hostname you are trying to connect to.

Although the webserver would know the hostname from Server Name Indication, the Host header is not obsolete, because the Server Name Indication information is only used within the TLS handshake. With an unsecured connection, there is no Server Name Indication at all, so the Host header is still valid (and necessary).

Another fun fact: Most webservers (if not all) reject your HTTP request if it does not contain exactly one Host header, even if it could be omitted because there is only the default vhost configured. That means the minimum required information in an http-(get-)request is the first line containing METHOD RESOURCE and PROTOCOL VERSION and at least the Host header, like this:

GET /someresource.html HTTP/1.1
Host: www.example.com

In the MDN Documentation on the "Host" header they actually phrase it like this:

A Host header field must be sent in all HTTP/1.1 request messages. A 400 (Bad Request) status code will be sent to any HTTP/1.1 request message that lacks a Host header field or contains more than one.

As mentioned by Darrel Miller, the complete specs can be found in RFC7230.

Max size of URL parameters in _GET

Ok, it seems that some versions of PHP have a limitation of length of GET params:

Please note that PHP setups with the suhosin patch installed will have a default limit of 512 characters for get parameters. Although bad practice, most browsers (including IE) supports URLs up to around 2000 characters, while Apache has a default of 8000.

To add support for long parameters with suhosin, add suhosin.get.max_value_length = <limit> in php.ini

Source: http://www.php.net/manual/en/reserved.variables.get.php#101469

How to calculate the sum of the datatable column in asp.net?

You can do like..

DataRow[] dr = dtbl.Select("SUM(Amount)");
txtTotalAmount.Text = Convert.ToString(dr[0]);

Setting "checked" for a checkbox with jQuery

If you are using .prop('checked', true|false) and don’t have changed checkbox, you need to add trigger('click') like this:

// Check
$('#checkboxF1').prop( "checked", true).trigger('click');


// Uncheck
$('#checkboxF1').prop( "checked", false).trigger('click');

Convert a negative number to a positive one in JavaScript

My minimal approach

For converting negative number to positive & vice-versa

_x000D_
_x000D_
var num = -24;_x000D_
num -= num*2;_x000D_
console.log(num)_x000D_
// result = 24
_x000D_
_x000D_
_x000D_

How to show code but hide output in RMarkdown?

For muting library("name_of_library") codes, meanly just showing the codes, {r loadlib, echo=T, results='hide', message=F, warning=F} is great. And imho a better way than library(package, warn.conflicts=F, quietly=T)

What size do you use for varchar(MAX) in your parameter declaration?

If you do something like this:

    cmd.Parameters.Add("@blah",SqlDbType.VarChar).Value = "some large text";

size will be taken from "some large text".Length

This can be problematic when it's an output parameter, you get back no more characters then you put as input.

Skip certain tables with mysqldump

For sake of completeness, here is a script which actually could be a one-liner to get a backup from a database, excluding (ignoring) all the views. The db name is assumed to be employees:

ignore=$(mysql --login-path=root1 INFORMATION_SCHEMA \
    --skip-column-names --batch \
    -e "select 
          group_concat(
            concat('--ignore-table=', table_schema, '.', table_name) SEPARATOR ' '
          ) 
        from tables 
        where table_type = 'VIEW' and table_schema = 'employees'")

mysqldump --login-path=root1 --column-statistics=0 --no-data employees $ignore > "./backups/som_file.sql"   

You can update the logic of the query. In general using group_concat and concat you can generate almost any desired string or shell command.

Only detect click event on pseudo-element

None of these answers are reliable, and mine wont be much more reliable.

Caveats aside, if you do get into the lucky scenario where the element you're trying to have clicked doesn't have padding (such that all of the "inner" space of the element is completely covered by sub-elements), then you can check the target of the click event against the container itself. If it matches, that means you've clicked a :before or :after element.

Obviously this would not be feasible with both types (before and after) however I have implemented it as a hack/speed fix and it is working very well, without a bunch of position checking, which may be inaccurate depending on about a million different factors.

Jquery how to find an Object by attribute in an Array

No need for jQuery.

JavaScript arrays have a find method, so you can achieve that in one line:

array.find((o) => { return o[propertyName] === propertyValue }

Example


const purposeObjects = [
    {purpose: "daily"},
    {purpose: "weekly"},
    {purpose: "monthly"}
];

purposeObjects.find((o) => { return o["purpose"] === "weekly" }

// output -> {purpose: "weekly"}

If you need IE compatibility, import this polyfill in your code.

Find and replace Android studio

If you use refactor->rename for the name of the file, everywhere the file is used in your project the refactor will replace it.

I have already rename variables, xml file, java file, multiple drawable and after the operation I could build directly without error.

Do a back-up of your project and try to see if it work for you.

What is the difference between an int and an Integer in Java and C#?

Java:

int, double, long, byte, float, double, short, boolean, char - primitives. Used for hold the basic data types supported by the language. the primitive types are not part of the object hierarchy, and they do not inherit Object. Thet can'be pass by reference to a method.

Double, Float, Long, Integer, Short, Byte, Character, and Boolean, are type Wrappers, packaged in java.lang. All of the numeric type wrappers define constructors that allow an object to be constructed from a given value, or a string representation of that value. Using objects can add an overhead to even the simplest of calculations.

Beginning with JDK 5, Java has included two very helpful features: autoboxing and autounboxing. Autoboxing/unboxing greatly simplifies and streamlines code that must convert primitive types into objects, and vice versa.

Example of constructors:

Integer(int num)
Integer(String str) throws NumberFormatException
Double(double num)
Double(String str) throws NumberFormatException

Example of boxing/unboxing:

class ManualBoxing {
        public static void main(String args[]) {
        Integer objInt = new Integer(20);  // Manually box the value 20.
        int i = objInt.intValue();  // Manually unbox the value 20
        System.out.println(i + " " + iOb); // displays 20 20
    }
}

Example of autoboxing/autounboxing:

class AutoBoxing {
    public static void main(String args[]) {
        Integer objInt = 40; // autobox an int
        int i = objInt ; // auto-unbox
        System.out.println(i + " " + iOb); // displays 40 40
    }
}

P.S. Herbert Schildt's book was taken as a reference.

How to add image in Flutter

How to include images in your app

1. Create an assets/images folder

  • This should be located in the root of your project, in the same folder as your pubspec.yaml file.
  • In Android Studio you can right click in the Project view
  • You don't have to call it assets or images. You don't even need to make images a subfolder. Whatever name you use, though, is what you will regester in the pubspec.yaml file.

2. Add your image to the new folder

  • You can just copy your image into assets/images. The relative path of lake.jpg, for example, would be assets/images/lake.jpg.

3. Register the assets folder in pubspec.yaml

  • Open the pubspec.yaml file that is in the root of your project.

  • Add an assets subsection to the flutter section like this:

      flutter:
        assets:
          - assets/images/lake.jpg
    
  • If you have multiple images that you want to include then you can leave off the file name and just use the directory name (include the final /):

      flutter:
        assets:
          - assets/images/
    

4. Use the image in code

  • Get the asset in an Image widget with Image.asset('assets/images/lake.jpg').

  • The entire main.dart file is here:

      import 'package:flutter/material.dart';
    
      void main() => runApp(MyApp());
    
      class MyApp extends StatelessWidget {
        @override
        Widget build(BuildContext context) {
          return MaterialApp(
            home: Scaffold(
              appBar: AppBar(
                title: Text("Image from assets"),
              ),
              body: Image.asset('assets/images/lake.jpg'), //   <--- image
            ),
          );
        }
      }
    

5. Restart your app

When making changes to pubspec.yaml I find that I often need to completely stop my app and restart it again, especially when adding assets. Otherwise I get a crash.

Running the app now you should have something like this:

enter image description here

Further reading

  • See the documentation for how to do things like provide alternate images for different densities.

Videos

The first video here goes into a lot of detail about how to include images in your app. The second video covers more about how to adjust how they look.

Get HTML code using JavaScript with a URL

Edit: doesnt work yet...

Add this to your JS:

var src = fetch('https://page.com')

It saves the source of page.com to variable 'src'

Can you call ko.applyBindings to bind a partial view?

ko.applyBindings accepts a second parameter that is a DOM element to use as the root.

This would let you do something like:

<div id="one">
  <input data-bind="value: name" />
</div>

<div id="two">
  <input data-bind="value: name" />
</div>

<script type="text/javascript">
  var viewModelA = {
     name: ko.observable("Bob")
  };

  var viewModelB = {
     name: ko.observable("Ted")
  };

  ko.applyBindings(viewModelA, document.getElementById("one"));
  ko.applyBindings(viewModelB, document.getElementById("two"));
</script>

So, you can use this technique to bind a viewModel to the dynamic content that you load into your dialog. Overall, you just want to be careful not to call applyBindings multiple times on the same elements, as you will get multiple event handlers attached.

How should you diagnose the error SEHException - External component has thrown an exception

if you are having a problem as describe in this post:

asp.net mvc debugger throwing SEHException

then the solution is:

if you have any application from Trusteer (like rapport or anything ) just uninstall and reboot your system, it'll work fine ... found this solution here:

http://forums.asp.net/t/1704958.aspx/8/10?Re+SEHException+thrown+when+I+run+the+application

response.sendRedirect() from Servlet to JSP does not seem to work

Instead of using

response.sendRedirect("/demo.jsp");

Which does a permanent redirect to an absolute URL path,

Rather use RequestDispatcher. Example:

RequestDispatcher dispatcher = request.getRequestDispatcher("demo.jsp");
dispatcher.forward(request, response);

"pip install json" fails on Ubuntu

While it's true that json is a built-in module, I also found that on an Ubuntu system with python-minimal installed, you DO have python but you can't do import json. And then I understand that you would try to install the module using pip!

If you have python-minimal you'll get a version of python with less modules than when you'd typically compile python yourself, and one of the modules you'll be missing is the json module. The solution is to install an additional package, called libpython2.7-stdlib, to install all 'default' python libraries.

sudo apt install libpython2.7-stdlib

And then you can do import json in python and it would work!

How do I extend a class with c# extension methods?

Extension methods are syntactic sugar for making static methods whose first parameter is an instance of type T look as if they were an instance method on T.

As such the benefit is largely lost where you to make 'static extension methods' since they would serve to confuse the reader of the code even more than an extension method (since they appear to be fully qualified but are not actually defined in that class) for no syntactical gain (being able to chain calls in a fluent style within Linq for example).

Since you would have to bring the extensions into scope with a using anyway I would argue that it is simpler and safer to create:

public static class DateTimeUtils
{
    public static DateTime Tomorrow { get { ... } }
}

And then use this in your code via:

WriteLine("{0}", DateTimeUtils.Tomorrow)

Strings and character with printf

If you want to display a single character then you can also use name[0] instead of using pointer.

It will serve your purpose but if you want to display full string using %c, you can try this:

#include<stdio.h>
void main()
{ 
    char name[]="siva";
    int i;
    for(i=0;i<4;i++)
    {
        printf("%c",*(name+i));
    }
} 

Response to preflight request doesn't pass access control check

You are running into CORS issues.

There are several ways to fix/workaround this.

  1. Turn off CORS. For example: how to turn off cors in chrome
  2. Use a plugin for your browser
  3. Use a proxy such as nginx. example of how to set up
  4. Go through the necessary setup for your server. This is more a factor of the web server you have loaded on your EC2 instance (presuming this is what you mean by "Amazon web service"). For your specific server you can refer to the enable CORS website.

More verbosely, you are trying to access api.serverurl.com from localhost. This is the exact definition of cross domain request.

By either turning it off just to get your work done (OK, but poor security for you if you visit other sites and just kicks the can down the road) you can use a proxy which makes your browser think all requests come from local host when really you have local server that then calls the remote server.

so api.serverurl.com might become localhost:8000/api and your local nginx or other proxy will send to the correct destination.


Now by popular demand, 100% more CORS info....same great taste!


Bypassing CORS is exactly what is shown for those simply learning the front end. https://codecraft.tv/courses/angular/http/http-with-promises/

When to use EntityManager.find() vs EntityManager.getReference() with JPA

Sssuming you have a parent Post entity and a child PostComment as illustrated in the following diagram:

enter image description here

If you call find when you try to set the @ManyToOne post association:

PostComment comment = new PostComment();
comment.setReview("Just awesome!");
 
Post post = entityManager.find(Post.class, 1L);
comment.setPost(post);
 
entityManager.persist(comment);

Hibernate will execute the following statements:

SELECT p.id AS id1_0_0_,
       p.title AS title2_0_0_
FROM   post p
WHERE p.id = 1
 
INSERT INTO post_comment (post_id, review, id)
VALUES (1, 'Just awesome!', 1)

The SELECT query is useless this time because we don’t need the Post entity to be fetched. We only want to set the underlying post_id Foreign Key column.

Now, if you use getReference instead:

PostComment comment = new PostComment();
comment.setReview("Just awesome!");
 
Post post = entityManager.getReference(Post.class, 1L);
comment.setPost(post);
 
entityManager.persist(comment);

This time, Hibernate will issue just the INSERT statement:

INSERT INTO post_comment (post_id, review, id)
VALUES (1, 'Just awesome!', 1)

Unlike find, the getReference only returns an entity Proxy which only has the identifier set. If you access the Proxy, the associated SQL statement will be triggered as long as the EntityManager is still open.

However, in this case, we don’t need to access the entity Proxy. We only want to propagate the Foreign Key to the underlying table record so loading a Proxy is sufficient for this use case.

When loading a Proxy, you need to be aware that a LazyInitializationException can be thrown if you try to access the Proxy reference after the EntityManager is closed.

TypeError: Object of type 'bytes' is not JSON serializable

I was dealing with this issue today, and I knew that I had something encoded as a bytes object that I was trying to serialize as json with json.dump(my_json_object, write_to_file.json). my_json_object in this case was a very large json object that I had created, so I had several dicts, lists, and strings to look at to find what was still in bytes format.

The way I ended up solving it: the write_to_file.json will have everything up to the bytes object that is causing the issue.

In my particular case this was a line obtained through

for line in text:
    json_object['line'] = line.strip()

I solved by first finding this error with the help of the write_to_file.json, then by correcting it to:

for line in text:
    json_object['line'] = line.strip().decode()

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'customerService' is defined

By reading your exception , It's sure that you forgot to autowire customerService

You should autowire your customerservice .

make following changes in your controller class

@Controller
public class CustomerController{

    @Autowired
    private Customerservice customerservice;
......other code......

}

Again your service implementation class

write

@Service
public class CustomerServiceImpl implements CustomerService {
    @Autowired
    private CustomerDAO customerDAO;
......other code......

.....add transactional methods
}

If you are using hibernate make necessary changes in your applicationcontext xml file(configuration of session factory is needed).

you should autowire sessionFactory set method in your DAO mplementation

please find samle application context :

<?xml  version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:lang="http://www.springframework.org/schema/lang"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd
        http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:annotation-config />
    <context:component-scan base-package="com.sparkle" />
    <!-- Configures the @Controller programming model -->
    <mvc:annotation-driven />

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" 
            p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" p:order="0" />

    <bean id="messageSource"
        class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basename" value="classpath:messages" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>
    <!-- <bean id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:location="/WEB-INF/jdbc.properties" /> -->

     <bean id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">         
        <list>
            <value>/WEB-INF/jdbc.properties</value>          

        </list>    
    </property>     
    </bean>




    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource"
        p:driverClassName="${jdbc.driverClassName}"
        p:url="${jdbc.databaseurl}" p:username="${jdbc.username}"
        p:password="${jdbc.password}" />


    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation">
            <value>classpath:hibernate.cfg.xml</value>
        </property>
        <property name="configurationClass">
            <value>org.hibernate.cfg.AnnotationConfiguration</value>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${jdbc.dialect}</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

    <tx:annotation-driven />


   <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"
          p:sessionFactory-ref="sessionFactory"/>


</beans>

note that i am using jdbc.properties file for jdbc url and driver specification

Bootstrap 4 card-deck with number of columns based on viewport

@Zim provided a great solution above (well deserved up-vote from me), however, it didn't quite fit what I needed since I was implementing this in Jekyll and wanted my card deck to automatically update every time I added a post to my site. Growing a card deck such as this with each new post is straight forward in Jekyll, the challenge was to correctly place the breakpoints. My solution make use of additional liquid tags and modulo mathematics.

While this question is old, I came across it and found it useful, and maybe someday someone will come along wanting to do this with Jekyll.

<div class = "container">
  <div class = "card-deck">

    {% for post in site.posts %}
      <div class = "card border-0 mt-2">
        <a href = "{{ post.url }}"><img src = "{{ site.baseurl }}{{ post.image }}" class = "mx-auto" alt = "..."></a>
        <div class = "card-body">
          <h5 class = "card-title"><a href = "{{ post.url }}">{{ post.title }}</a></h5>
          <span>Published: {{ post.date | date_to_long_string }} </span>
          <p class = "text-muted">{{ post.excerpt }}</p>
        </div>
        <div class = "card-footer bg-white border-0"><a href = "{{ post.url }}" class = "btn btn-primary">Read more</a></div>
      </div>

      <!-- Use modulo to add divs to handle break points -->
      {% assign sm = forloop.index | modulo: 2 %}
      {% assign md = forloop.index | modulo: 3 %}
      {% assign lg = forloop.index | modulo: 4 %}
      {% assign xl = forloop.index | modulo: 5 %}

      {% if sm == 0 %}
        <div class="w-100 d-none d-sm-block d-md-none"><!-- wrap every 2 on sm--></div>
      {% endif %}

      {% if md == 0 %}
        <div class="w-100 d-none d-md-block d-lg-none"><!-- wrap every 3 on md--></div>
      {% endif %}

      {% if lg == 0 %}
        <div class="w-100 d-none d-lg-block d-xl-none"><!-- wrap every 4 on lg--></div>
      {% endif %}

      {% if xl == 0 %}
        <div class="w-100 d-none d-xl-block"><!-- wrap every 5 on xl--></div>
      {% endif %}

    {% endfor %}
  </div>
</div>

This whole code block can be used directly in a website or saved in your Jekyll project _includes folder.

How to format a URL to get a file from Amazon S3?

As @stevebot said, do this:

https://<bucket-name>.s3.amazonaws.com/<key>

The one important thing I would like to add is that you either have to make your bucket objects all publicly accessible OR you can add a custom policy to your bucket policy. That custom policy could allow traffic from your network IP range or a different credential.

How to automatically add user account AND password with a Bash script?

You can run the passwd command and send it piped input. So, do something like:

echo thePassword | passwd theUsername --stdin

Compare if BigDecimal is greater than zero

This works too:

value > BigDecimal.ZERO

How to resolve ORA 00936 Missing Expression Error?

This answer is not the answer for the above mentioned question but it is related to same topic and might be useful for people searching for same error.

I faced the same error when I executed below mentioned query.

select OR.* from ORDER_REL_STAT OR

problem with above query was OR is keyword so it was expecting other values when I replaced with some other alias it worked fine.

How to verify Facebook access token?

Exchange Access Token for Mobile Number and Country Code (Server Side OR Client Side)

You can get the mobile number with your access_token with this API https://graph.accountkit.com/v1.1/me/?access_token=xxxxxxxxxxxx. Maybe, once you have the mobile number and the id, you can work with it to verify the user with your server & database.

xxxxxxxxxx above is the Access Token

Example Response :

{
   "id": "61940819992708",
   "phone": {
      "number": "+91XX82923912",
      "country_prefix": "91",
      "national_number": "XX82923912"
   }
}


Exchange Auth Code for Access Token (Server Side)

If you have an Auth Code instead, you can first get the Access Token with this API - https://graph.accountkit.com/v1.1/access_token?grant_type=authorization_code&code=xxxxxxxxxx&access_token=AA|yyyyyyyyyy|zzzzzzzzzz

xxxxxxxxxx, yyyyyyyyyy and zzzzzzzzzz above are the Auth Code, App ID and App Secret respectively.

Example Response

{
   "id": "619XX819992708",
   "access_token": "EMAWdcsi711meGS2qQpNk4XBTwUBIDtqYAKoZBbBZAEZCZAXyWVbqvKUyKgDZBniZBFwKVyoVGHXnquCcikBqc9ROF2qAxLRrqBYAvXknwND3dhHU0iLZCRwBNHNlyQZD",
   "token_refresh_interval_sec": XX92000
}

Note - This is preferred on the server-side since the API requires the APP Secret which is not meant to be shared for security reasons.

Good Luck.

C free(): invalid pointer

You're attempting to free something that isn't a pointer to a "freeable" memory address. Just because something is an address doesn't mean that you need to or should free it.

There are two main types of memory you seem to be confusing - stack memory and heap memory.

  • Stack memory lives in the live span of the function. It's temporary space for things that shouldn't grow too big. When you call the function main, it sets aside some memory for your variables you've declared (p,token, and so on).

  • Heap memory lives from when you malloc it to when you free it. You can use much more heap memory than you can stack memory. You also need to keep track of it - it's not easy like stack memory!

You have a few errors:

  • You're trying to free memory that's not heap memory. Don't do that.

  • You're trying to free the inside of a block of memory. When you have in fact allocated a block of memory, you can only free it from the pointer returned by malloc. That is to say, only from the beginning of the block. You can't free a portion of the block from the inside.

For your bit of code here, you probably want to find a way to copy relevant portion of memory to somewhere else...say another block of memory you've set aside. Or you can modify the original string if you want (hint: char value 0 is the null terminator and tells functions like printf to stop reading the string).

EDIT: The malloc function does allocate heap memory*.

"9.9.1 The malloc and free Functions

The C standard library provides an explicit allocator known as the malloc package. Programs allocate blocks from the heap by calling the malloc function."

~Computer Systems : A Programmer's Perspective, 2nd Edition, Bryant & O'Hallaron, 2011

EDIT 2: * The C standard does not, in fact, specify anything about the heap or the stack. However, for anyone learning on a relevant desktop/laptop machine, the distinction is probably unnecessary and confusing if anything, especially if you're learning about how your program is stored and executed. When you find yourself working on something like an AVR microcontroller as H2CO3 has, it is definitely worthwhile to note all the differences, which from my own experience with embedded systems, extend well past memory allocation.

Selecting Multiple Values from a Dropdown List in Google Spreadsheet

If the answers must be constrained to Google Sheets, this answer works but it has limitations and is clumsy enough UX that it may be hard to get others to adopt. In trying to solve this problem I've found that, for many applications, Airtable solves this by allowing for multi-select columns and the UX is worlds better.

Remove Object from Array using JavaScript

Use splice function on arrays. Specify the position of the start element and the length of the subsequence you want to remove.

someArray.splice(pos, 1);

Support for ES6 in Internet Explorer 11

The statement from Microsoft regarding the end of Internet Explorer 11 support mentions that it will continue to receive security updates, compatibility fixes, and technical support until its end of life. The wording of this statement leads me to believe that Microsoft has no plans to continue adding features to Internet Explorer 11, and instead will be focusing on Edge.

If you require ES6 features in Internet Explorer 11, check out a transpiler such as Babel.

Convert HashBytes to VarChar

With personal experience of using the following code within a Stored Procedure which Hashed a SP Variable I can confirm, although undocumented, this combination works 100% as per my example:

@var=SUBSTRING(master.dbo.fn_varbintohexstr(HashBytes('SHA2_512', @SPvar)), 3, 128)

remove all special characters in java

Your problem is that the indices returned by match.start() correspond to the position of the character as it appeared in the original string when you matched it; however, as you rewrite the string c every time, these indices become incorrect.

The best approach to solve this is to use replaceAll, for example:

        System.out.println(c.replaceAll("[^a-zA-Z0-9]", ""));

Spring get current ApplicationContext

Simply inject it..

@Autowired
private ApplicationContext appContext;

or implement this interface: ApplicationContextAware

unresolved external symbol __imp__fprintf and __imp____iob_func, SDL2

As answered above, the right answer is to compile everything with VS2015, but for interest the following is my analysis of the problem.

This symbol does not appear to be defined in any static library provided by Microsoft as part of VS2015, which is rather peculiar since all others are. To discover why, we need to look at the declaration of that function and, more importantly, how it's used.

Here's a snippet from the Visual Studio 2008 headers:

_CRTIMP FILE * __cdecl __iob_func(void);
#define stdin (&__iob_func()[0])
#define stdout (&__iob_func()[1])
#define stderr (&__iob_func()[2])

So we can see that the job of the function is to return the start of an array of FILE objects (not handles, the "FILE *" is the handle, FILE is the underlying opaque data structure storing the important state goodies). The users of this function are the three macros stdin, stdout and stderr which are used for various fscanf, fprintf style calls.

Now let's take a look at how Visual Studio 2015 defines the same things:

_ACRTIMP_ALT FILE* __cdecl __acrt_iob_func(unsigned);
#define stdin (__acrt_iob_func(0))
#define stdout (__acrt_iob_func(1))
#define stderr (__acrt_iob_func(2))

So the approach has changed for the replacement function to now return the file handle rather than the address of the array of file objects, and the macros have changed to simply call the function passing in an identifying number.

So why can't they/we provide a compatible API? There are two key rules which Microsoft can't contravene in terms of their original implementation via __iob_func:

  1. There must be an array of three FILE structures which can be indexed in the same manner as before.
  2. The structural layout of FILE cannot change.

Any change in either of the above would mean existing compiled code linked against that would go badly wrong if that API is called.

Let's take a look at how FILE was/is defined.

First the VS2008 FILE definition:

struct _iobuf {
        char *_ptr;
        int   _cnt;
        char *_base;
        int   _flag;
        int   _file;
        int   _charbuf;
        int   _bufsiz;
        char *_tmpfname;
        };
typedef struct _iobuf FILE;

And now the VS2015 FILE definition:

typedef struct _iobuf
{
    void* _Placeholder;
} FILE;

So there is the crux of it: the structure has changed shape. Existing compiled code referring to __iob_func relies upon the fact that the data returned is both an array that can be indexed and that in that array the elements are the same distance apart.

The possible solutions mentioned in the answers above along these lines would not work (if called) for a few reasons:

FILE _iob[] = {*stdin, *stdout, *stderr};

extern "C" FILE * __cdecl __iob_func(void)
{
    return _iob;
}

The FILE array _iob would be compiled with VS2015 and so it would be laid out as a block of structures containing a void*. Assuming 32-bit alignment, these elements would be 4 bytes apart. So _iob[0] is at offset 0, _iob[1] is at offset 4 and _iob[2] is at offset 8. The calling code will instead expect FILE to be much longer, aligned at 32 bytes on my system, and so it will take the address of the returned array and add 0 bytes to get to element zero (that one is okay), but for _iob[1] it will deduce that it needs to add 32 bytes and for _iob[2] it will deduce that it needs to add 64-bytes (because that's how it looked in the VS2008 headers). And indeed the disassembled code for VS2008 demonstrates this.

A secondary issue with the above solution is that it copies the content of the FILE structure (*stdin), not the FILE * handle. So any VS2008 code would be looking at a different underlying structure to VS2015. This might work if the structure only contained pointers, but that's a big risk. In any case the first issue renders this irrelevant.

The only hack I've been able to dream up is one in which __iob_func walks the call stack to work out which actual file handle they are looking for (based on the offset added to the returned address) and returns a computed value such that it gives the right answer. This is every bit as insane as it sounds, but the prototype for x86 only (not x64) is listed below for your amusement. It worked okay in my experiments, but your mileage may vary - not recommended for production use!

#include <windows.h>
#include <stdio.h>
#include <dbghelp.h>

/* #define LOG */

#if defined(_M_IX86)

#define GET_CURRENT_CONTEXT(c, contextFlags) \
  do { \
    c.ContextFlags = contextFlags; \
    __asm    call x \
    __asm x: pop eax \
    __asm    mov c.Eip, eax \
    __asm    mov c.Ebp, ebp \
    __asm    mov c.Esp, esp \
  } while(0);

#else

/* This should work for 64-bit apps, but doesn't */
#define GET_CURRENT_CONTEXT(c, contextFlags) \
  do { \
    c.ContextFlags = contextFlags; \
    RtlCaptureContext(&c); \
} while(0);

#endif

FILE * __cdecl __iob_func(void)
{
    CONTEXT c = { 0 };
    STACKFRAME64 s = { 0 };
    DWORD imageType;
    HANDLE hThread = GetCurrentThread();
    HANDLE hProcess = GetCurrentProcess();

    GET_CURRENT_CONTEXT(c, CONTEXT_FULL);

#ifdef _M_IX86
    imageType = IMAGE_FILE_MACHINE_I386;
    s.AddrPC.Offset = c.Eip;
    s.AddrPC.Mode = AddrModeFlat;
    s.AddrFrame.Offset = c.Ebp;
    s.AddrFrame.Mode = AddrModeFlat;
    s.AddrStack.Offset = c.Esp;
    s.AddrStack.Mode = AddrModeFlat;
#elif _M_X64
    imageType = IMAGE_FILE_MACHINE_AMD64;
    s.AddrPC.Offset = c.Rip;
    s.AddrPC.Mode = AddrModeFlat;
    s.AddrFrame.Offset = c.Rsp;
    s.AddrFrame.Mode = AddrModeFlat;
    s.AddrStack.Offset = c.Rsp;
    s.AddrStack.Mode = AddrModeFlat;
#elif _M_IA64
    imageType = IMAGE_FILE_MACHINE_IA64;
    s.AddrPC.Offset = c.StIIP;
    s.AddrPC.Mode = AddrModeFlat;
    s.AddrFrame.Offset = c.IntSp;
    s.AddrFrame.Mode = AddrModeFlat;
    s.AddrBStore.Offset = c.RsBSP;
    s.AddrBStore.Mode = AddrModeFlat;
    s.AddrStack.Offset = c.IntSp;
    s.AddrStack.Mode = AddrModeFlat;
#else
#error "Platform not supported!"
#endif

    if (!StackWalk64(imageType, hProcess, hThread, &s, &c, NULL, SymFunctionTableAccess64, SymGetModuleBase64, NULL))
    {
#ifdef LOG
        printf("Error: 0x%08X (Address: %p)\n", GetLastError(), (LPVOID)s.AddrPC.Offset);
#endif
        return NULL;
    }

    if (s.AddrReturn.Offset == 0)
    {
        return NULL;
    }

    {
        unsigned char const * assembly = (unsigned char const *)(s.AddrReturn.Offset);
#ifdef LOG
        printf("Code bytes proceeding call to __iob_func: %p: %02X,%02X,%02X\n", assembly, *assembly, *(assembly + 1), *(assembly + 2));
#endif
        if (*assembly == 0x83 && *(assembly + 1) == 0xC0 && (*(assembly + 2) == 0x20 || *(assembly + 2) == 0x40))
        {
            if (*(assembly + 2) == 32)
            {
                return (FILE*)((unsigned char *)stdout - 32);
            }
            if (*(assembly + 2) == 64)
            {
                return (FILE*)((unsigned char *)stderr - 64);
            }

        }
        else
        {
            return stdin;
        }
    }
    return NULL;
}

How can I tell when HttpClient has timed out?

From http://msdn.microsoft.com/en-us/library/system.net.http.httpclient.timeout.aspx

A Domain Name System (DNS) query may take up to 15 seconds to return or time out. If your request contains a host name that requires resolution and you set Timeout to a value less than 15 seconds, it may take 15 seconds or more before a WebException is thrown to indicate a timeout on your request.

You then get access to the Status property, see WebExceptionStatus

Iterating over each line of ls -l output

The read(1) utility along with output redirection of the ls(1) command will do what you want.

Single selection in RecyclerView

This might help for those who want a single radiobutton to work --> Radio Button RecycleView - Gist

If lambda expressions aren't supported, use this instead:

View.OnClickListener listener = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        notifyItemChanged(mSelectedItem); // to update last selected item.
        mSelectedItem = getAdapterPosition();
    }
};

Cheers

Best way to log POST data in Apache?

An easier option may be to log the POST data before it gets to the server. For web applications, I use Burp Proxy and set Firefox to use it as an HTTP/S proxy, and then I can watch (and mangle) data 'on the wire' in real time.

For making API requests without a browser, SoapUI is very useful and may show similar info. I would bet that you could probably configure SoapUI to connect through Burp as well (just a guess though).

Return value from a VBScript function

To return a value from a VBScript function, assign the value to the name of the function, like this:

Function getNumber
    getNumber = "423"
End Function

Hide/Show components in react native

checkincheckout = () => {
        this.setState({ visible: !this.state.visible })
}

render() {
        return (
{this.state.visible == false ?
        <View style={{ alignItems: 'center', flexDirection: 'row', marginTop: 50 }}>

        <View style={{ flex: 1, alignItems: 'center', flexDirection: 'column' }}>

            <TouchableOpacity onPress={() => this.checkincheckout()}>

                <Text style={{ color: 'white' }}>Click to Check in</Text>

            </TouchableOpacity>

        </View>

    </View>
:
<View style={{ alignItems: 'center', flexDirection: 'row', marginTop: 50 }}>

<View style={{ flex: 1, alignItems: 'center', flexDirection: 'column' }}>

   <TouchableOpacity onPress={() => this.checkincheckout()}>

        <Text style={{ color: 'white' }}>Click to Check out</Text>

    </TouchableOpacity>

</View>

</View>
 }

);
}

thats all. enjoy your coding...

Returning null in a method whose signature says return int?

int is a primitive, null is not a value that it can take on. You could change the method return type to return java.lang.Integer and then you can return null, and existing code that returns int will get autoboxed.

Nulls are assigned only to reference types, it means the reference doesn't point to anything. Primitives are not reference types, they are values, so they are never set to null.

Using the object wrapper java.lang.Integer as the return value means you are passing back an Object and the object reference can be null.

On delete cascade with doctrine2

There are two kinds of cascades in Doctrine:

1) ORM level - uses cascade={"remove"} in the association - this is a calculation that is done in the UnitOfWork and does not affect the database structure. When you remove an object, the UnitOfWork will iterate over all objects in the association and remove them.

2) Database level - uses onDelete="CASCADE" on the association's joinColumn - this will add On Delete Cascade to the foreign key column in the database:

@ORM\JoinColumn(name="father_id", referencedColumnName="id", onDelete="CASCADE")

I also want to point out that the way you have your cascade={"remove"} right now, if you delete a Child object, this cascade will remove the Parent object. Clearly not what you want.

How to get the mouse position without events (without moving the mouse)?

Real answer: No, it's not possible.

OK, I have just thought of a way. Overlay your page with a div that covers the whole document. Inside that, create (say) 2,000 x 2,000 <a> elements (so that the :hover pseudo-class will work in IE 6, see), each 1 pixel in size. Create a CSS :hover rule for those <a> elements that changes a property (let's say font-family). In your load handler, cycle through each of the 4 million <a> elements, checking currentStyle / getComputedStyle() until you find the one with the hover font. Extrapolate back from this element to get the co-ordinates within the document.

N.B. DON'T DO THIS.

Sorting dropdown alphabetically in AngularJS

For anyone who wants to sort the variable in third layer:

<select ng-option="friend.pet.name for friend in friends"></select>

you can do it like this

<select ng-option="friend.pet.name for friend in friends | orderBy: 'pet.name'"></select>

Creating a recursive method for Palindrome

Some of the codes are string heavy. Instead of creating substring which creates new object, we can just pass on indexes in recursive calls like below:

private static boolean isPalindrome(String str, int left, int right) {
    if(left >= right) {
        return true;
    }
    else {
        if(str.charAt(left) == str.charAt(right)) {

            return isPalindrome(str, ++left, --right);
        }
        else {
            return false;
        }
    }
}


 public static void main(String []args){
    String str = "abcdcbb"; 
    System.out.println(isPalindrome(str, 0, str.length()-1));
 }

Convert a binary NodeJS Buffer to JavaScript ArrayBuffer

I tried the above for a Float64Array and it just did not work.

I ended up realising that really the data needed to be read 'INTO' the view in correct chunks. This means reading 8 bytes at a time from the source Buffer.

Anyway this is what I ended up with...

var buff = new Buffer("40100000000000004014000000000000", "hex");
var ab = new ArrayBuffer(buff.length);
var view = new Float64Array(ab);

var viewIndex = 0;
for (var bufferIndex=0;bufferIndex<buff.length;bufferIndex=bufferIndex+8)            {

    view[viewIndex] = buff.readDoubleLE(bufferIndex);
    viewIndex++;
}

ng serve not detecting file changes automatically

Only need to run sudo ng serve to resolve the issue.

Recommended way to get hostname in Java

Although this topic has already been answered there's more to say.

First of all: Clearly we need some definitions here. The InetAddress.getLocalHost().getHostName() gives you the name of the host as seen from a network perspective. The problems with this approach are well documented in the other answers: it often requires a DNS lookup, it's ambiguous if the host has multiple network interfaces and it just plain fails sometimes (see below).

But on any OS there's another name as well. A name of the host that gets defined very early in the boot process, long before the network is initialized. Windows refers to this as computername, Linux calls it kernel hostname and Solaris uses the word nodename. I like best the word computername, so I'll use that word from now on.

Finding the computername

  • On Linux/Unix the computername is what you get from the C function gethostname(), or hostname command from shell or HOSTNAME environment variable in Bash-like shells.

  • On Windows the computername is what you get from environment variable COMPUTERNAME or Win32 GetComputerName function.

Java has no way of obtaining what I've defined as 'computername'. Sure, there are workarounds as described in other answers, like for Windows calling System.getenv("COMPUTERNAME"), but on Unix/Linux there's no good workaround without resorting to JNI/JNA or Runtime.exec(). If you don't mind a JNI/JNA solution then there's gethostname4j which is dead simple and very easy to use.

Let's move on with two examples, one from Linux and one from Solaris, which demonstrate how you can easily get into a situation where you cannot obtain the computername using standard Java methods.

Linux example

On a newly created system, where the host during installation has been named as 'chicago', we now change the so-called kernel hostname:

$ hostnamectl --static set-hostname dallas

Now the kernel hostname is 'dallas', as evident from the hostname command:

$ hostname
dallas

But we still have

$ cat /etc/hosts
127.0.0.1   localhost
127.0.0.1   chicago

There's no misconfiguration in this. It just means the host's networked name (or rather the name of the loopback interface) is different from the host's computername.

Now, try executing InetAddress.getLocalHost().getHostName() and it will throw java.net.UnknownHostException. You are basically stuck. There's no way to retrieve neither the value 'dallas' nor the value 'chicago'.

Solaris example

The example below is based on Solaris 11.3.

The host has deliberately been configured so that the loopback name <> nodename.

In other words we have:

$ svccfg -s system/identity:node listprop config
...
...
config/loopback             astring        chicago
config/nodename             astring        dallas

and the contents of /etc/hosts :

:1 chicago localhost
127.0.0.1 chicago localhost loghost

and the result of the hostname command would be:

$ hostname
dallas

Just like in the Linux example a call to InetAddress.getLocalHost().getHostName() will fail with

java.net.UnknownHostException: dallas:  dallas: node name or service name not known

Just like the Linux example you are now stuck. There's no way to retrieve neither the value 'dallas' nor the value 'chicago'.

When will you really struggle with this?

Very often you'll find that InetAddress.getLocalHost().getHostName() will indeed return a value which is equal to the computername. So there's no problem (except for the added overhead of name resolution).

The problem arises typically within PaaS environments where there's a difference between computername and the name of the loopback interface. For example people report problems in Amazon EC2.

Bug/RFE reports

A bit of searching reveals this RFE report : link1, link2. However, judging from the comments on that report the issue seems to have been largely misunderstood by the JDK team, so it is unlikely it will be addressed.

I like the comparison in the RFE to other programming languages.

Excel plot time series frequency with continuous xaxis

I would like to compliment Ram Narasimhans answer with some tips I found on an Excel blog

Non-uniformly distributed data can be plotted in excel in

  • X Y (Scatter Plots)
  • Linear plots with Date axis
    • These don't take time into account, only days.
    • This method is quite cumbersome as it requires translating your time units to days, months, or years.. then change the axis labels... Not Recommended

Just like Ram Narasimhan suggested, to have the points centered you will want the mid point but you don't need to move to a numeric format, you can stay in the time format.

1- Add the center point to your data series

+---------------+-------+------+
|    Time       | Time  | Freq |
+---------------+-------+------+
| 08:00 - 09:00 | 08:30 |  12  |
| 09:00 - 10:00 | 09:30 |  13  |
| 10:00 - 11:00 | 10:30 |  10  |
| 13:00 - 14:00 | 13:30 |   5  |
| 14:00 - 15:00 | 14:30 |  14  |
+---------------+-------+------+

2- Create a Scatter Plot

3- Excel allows you to specify time values for the axis options. Time values are a parts per 1 of a 24-hour day. Therefore if we want to 08:00 to 15:00, then we Set the Axis options to:

  • Minimum : Fix : 0.33333
  • Maximum : Fix : 0.625
  • Major unit : Fix : 0.041667

Line Scatter Plot


Alternative Display:

Make the points turn into columns:

To be able to represent these points as bars instead of just point we need to draw disjoint lines. Here is a way to go about getting this type of chart.

1- You're going to need to add several rows where we draw the line and disjoint the data

+-------+------+
| Time  | Freq |
+-------+------+
| 08:30 |   0  |
| 08:30 |  12  |
|       |      |
| 09:30 |   0  |
| 09:30 |  13  |
|       |      |
| 10:30 |   0  |
| 10:30 |  10  |
|       |      |
| 13:30 |   0  |
| 13:30 |   5  |
|       |      |
| 14:30 |   0  |
| 14:30 |  14  |
+-------+------+

2- Plot an X Y (Scatter) Chart with Lines.

3- Now you can tweak the data series to have a fatter line, no markers, etc.. to get a bar/column type chart with non-uniformly distributed data.

Bar-Line Scatter Plot

How do I convert between big-endian and little-endian values in C++?

From The Byte Order Fallacy by Rob Pike:

Let's say your data stream has a little-endian-encoded 32-bit integer. Here's how to extract it (assuming unsigned bytes):

i = (data[0]<<0) | (data[1]<<8) | (data[2]<<16) | (data[3]<<24);

If it's big-endian, here's how to extract it:

i = (data[3]<<0) | (data[2]<<8) | (data[1]<<16) | (data[0]<<24);

TL;DR: don't worry about your platform native order, all that counts is the byte order of the stream your are reading from, and you better hope it's well defined.

Note: it was remarked in the comment that absent explicit type conversion, it was important that data be an array of unsigned char or uint8_t. Using signed char or char (if signed) will result in data[x] being promoted to an integer and data[x] << 24 potentially shifting a 1 into the sign bit which is UB.

Resize Cross Domain Iframe Height

If you have access to manipulate the code of the site you are loading, the following should provide a comprehensive method to updating the height of the iframe container anytime the height of the framed content changes.

Add the following code to the pages you are loading (perhaps in a header). This code sends a message containing the height of the HTML container any time the DOM is updated (if you're lazy loading) or the window is resized (when the user modifies the browser).

window.addEventListener("load", function(){
    if(window.self === window.top) return; // if w.self === w.top, we are not in an iframe 
    send_height_to_parent_function = function(){
        var height = document.getElementsByTagName("html")[0].clientHeight;
        //console.log("Sending height as " + height + "px");
        parent.postMessage({"height" : height }, "*");
    }
    // send message to parent about height updates
    send_height_to_parent_function(); //whenever the page is loaded
    window.addEventListener("resize", send_height_to_parent_function); // whenever the page is resized
    var observer = new MutationObserver(send_height_to_parent_function);           // whenever DOM changes PT1
    var config = { attributes: true, childList: true, characterData: true, subtree:true}; // PT2
    observer.observe(window.document, config);                                            // PT3 
});

Add the following code to the page that the iframe is stored on. This will update the height of the iframe, given that the message came from the page that that iframe loads.

<script>
window.addEventListener("message", function(e){
    var this_frame = document.getElementById("healthy_behavior_iframe");
    if (this_frame.contentWindow === e.source) {
        this_frame.height = e.data.height + "px";
        this_frame.style.height = e.data.height + "px";
    }
})
</script>

where is create-react-app webpack config and files?

A lot of people come to this page with the goal of finding the webpack config and files in order to add their own configuration to them. Another way to achieve this without running npm run eject is to use react-app-rewired. This allows you to overwrite your webpack config file without ejecting.

Using Regular Expressions to Extract a Value in Java

Full example:

private static final Pattern p = Pattern.compile("^([a-zA-Z]+)([0-9]+)(.*)");
public static void main(String[] args) {
    // create matcher for pattern p and given string
    Matcher m = p.matcher("Testing123Testing");

    // if an occurrence if a pattern was found in a given string...
    if (m.find()) {
        // ...then you can use group() methods.
        System.out.println(m.group(0)); // whole matched expression
        System.out.println(m.group(1)); // first expression from round brackets (Testing)
        System.out.println(m.group(2)); // second one (123)
        System.out.println(m.group(3)); // third one (Testing)
    }
}

Since you're looking for the first number, you can use such regexp:

^\D+(\d+).*

and m.group(1) will return you the first number. Note that signed numbers can contain a minus sign:

^\D+(-?\d+).*

Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

Here's what worked for me:

ln -s /var/lib/mysql/mysql.sock /tmp/mysql.sock
service mysqld restart

Loading existing .html file with android WebView

paste your .html file in assets folder of your project folder. and create an xml file in layout folder with the fol code: my.xml:

<WebView  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/webview"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
    />

add fol code in activity

setContentView(R.layout.my);
    WebView mWebView = null;
    mWebView = (WebView) findViewById(R.id.webview);
    mWebView.getSettings().setJavaScriptEnabled(true);
    mWebView.loadUrl("file:///android_asset/new.html"); //new.html is html file name.

Can't append <script> element

Another way you can do it if you want to append code is using the document.createElement method but then using .innerHTML instead of .src.

var script = document.createElement( 'script' );
script.type = 'text/javascript';
script.innerHTML = 'alert("Hey there... you just appended this script to the body");';
$("body").append( script );

Javascript - removing undefined fields from an object

Here's a plain javascript (no library required) solution:

function removeUndefinedProps(obj) {
    for (var prop in obj) {
        if (obj.hasOwnProperty(prop) && obj[prop] === undefined) {
            delete obj[prop];
        }
    }
}

Working demo: http://jsfiddle.net/jfriend00/djj5g5fu/

How to generate a random int in C?

Hearing a good explanation of why using rand() to produce uniformly distributed random numbers in a given range is a bad idea, I decided to take a look at how skewed the output actually is. My test case was fair dice throwing. Here's the C code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[])
{
    int i;
    int dice[6];

    for (i = 0; i < 6; i++) 
      dice[i] = 0;
    srand(time(NULL));

    const int TOTAL = 10000000;
    for (i = 0; i < TOTAL; i++)
      dice[(rand() % 6)] += 1;

    double pers = 0.0, tpers = 0.0;
    for (i = 0; i < 6; i++) {
      pers = (dice[i] * 100.0) / TOTAL;
      printf("\t%1d  %5.2f%%\n", dice[i], pers);
      tpers += pers;
    }
    printf("\ttotal:  %6.2f%%\n", tpers);
}

and here's its output:

 $ gcc -o t3 t3.c
 $ ./t3 
        1666598  16.67%     
        1668630  16.69%
        1667682  16.68%
        1666049  16.66%
        1665948  16.66%
        1665093  16.65%
        total:  100.00%
 $ ./t3     
        1667634  16.68%
        1665914  16.66%
        1665542  16.66%
        1667828  16.68%
        1663649  16.64%
        1669433  16.69%
        total:  100.00%

I don't know how uniform you need your random numbers to be, but the above appears uniform enough for most needs.

Edit: it would be a good idea to initialize the PRNG with something better than time(NULL).

The 'packages' element is not declared

Use <packages xmlns="urn:packages">in the place of <packages>

How to make use of SQL (Oracle) to count the size of a string?

Regardless to Your example

select length('Burger') from dual;

I hope this will help :)

Remove a symlink to a directory

On CentOS, just run rm linkname and it will ask to "remove symbolic link?". Type Y and Enter, the link will be gone and the directory be safe.

In bootstrap how to add borders to rows without adding up?

You can remove the border from top if the element is sibling of the row . Add this to css :

.row + .row {
   border-top:0;
}

Here is the link to the fiddle http://jsfiddle.net/7cb3Y/3/

React navigation goBack() and update parent state

You can pass a callback function as parameter when you call navigate like this:

  const DEMO_TOKEN = await AsyncStorage.getItem('id_token');
  if (DEMO_TOKEN === null) {
    this.props.navigation.navigate('Login', {
      onGoBack: () => this.refresh(),
    });
    return -3;
  } else {
    this.doSomething();
  }

And define your callback function:

refresh() {
  this.doSomething();
}

Then in the login/registration view, before goBack, you can do this:

await AsyncStorage.setItem('id_token', myId);
this.props.navigation.state.params.onGoBack();
this.props.navigation.goBack();

Update for React Navigation v5:

await AsyncStorage.setItem('id_token', myId);
this.props.route.params.onGoBack();
this.props.navigation.goBack();

How can I solve "Non-static method xxx:xxx() should not be called statically in PHP 5.4?

I don't suggest you just hidding the stricts errors on your project. Intead, you should turn your method to static or try to creat a new instance of the object:

$var = new YourClass();
$var->method();

You can also use the new way to do the same since PHP 5.4:

(new YourClass)->method();

I hope it helps you!

How can I get the assembly file version

When I want to access the application file version (what is set in Assembly Information -> File version), say to set a label's text to it on form load to display the version, I have just used

versionlabel.Text = "Version " + Application.ProductVersion;

This approach requires a reference to System.Windows.Forms.

Javascript array search and remove string?

List of One Liners

Let's solve this problem for this array:

var array = ['A', 'B', 'C'];

1. Remove only the first: Use If you are sure that the item exist

array.splice(array.indexOf('B'), 1);

2. Remove only the last: Use If you are sure that the item exist

array.splice(array.lastIndexOf('B'), 1);

3. Remove all occurrences:

array = array.filter(v => v !== 'B'); 

How to use XMLReader in PHP?

Most of my XML parsing life is spent extracting nuggets of useful information out of truckloads of XML (Amazon MWS). As such, my answer assumes you want only specific information and you know where it is located.

I find the easiest way to use XMLReader is to know which tags I want the information out of and use them. If you know the structure of the XML and it has lots of unique tags, I find that using the first case is the easy. Cases 2 and 3 are just to show you how it can be done for more complex tags. This is extremely fast; I have a discussion of speed over on What is the fastest XML parser in PHP?

The most important thing to remember when doing tag-based parsing like this is to use if ($myXML->nodeType == XMLReader::ELEMENT) {... - which checks to be sure we're only dealing with opening nodes and not whitespace or closing nodes or whatever.

function parseMyXML ($xml) { //pass in an XML string
    $myXML = new XMLReader();
    $myXML->xml($xml);

    while ($myXML->read()) { //start reading.
        if ($myXML->nodeType == XMLReader::ELEMENT) { //only opening tags.
            $tag = $myXML->name; //make $tag contain the name of the tag
            switch ($tag) {
                case 'Tag1': //this tag contains no child elements, only the content we need. And it's unique.
                    $variable = $myXML->readInnerXML(); //now variable contains the contents of tag1
                    break;

                case 'Tag2': //this tag contains child elements, of which we only want one.
                    while($myXML->read()) { //so we tell it to keep reading
                        if ($myXML->nodeType == XMLReader::ELEMENT && $myXML->name === 'Amount') { // and when it finds the amount tag...
                            $variable2 = $myXML->readInnerXML(); //...put it in $variable2. 
                            break;
                        }
                    }
                    break;

                case 'Tag3': //tag3 also has children, which are not unique, but we need two of the children this time.
                    while($myXML->read()) {
                        if ($myXML->nodeType == XMLReader::ELEMENT && $myXML->name === 'Amount') {
                            $variable3 = $myXML->readInnerXML();
                            break;
                        } else if ($myXML->nodeType == XMLReader::ELEMENT && $myXML->name === 'Currency') {
                            $variable4 = $myXML->readInnerXML();
                            break;
                        }
                    }
                    break;

            }
        }
    }
$myXML->close();
}

What are some reasons for jquery .focus() not working?

I found that focus does not work when trying to get a focus on a text element (such as a notice div), but does work when focusing on input fields.

Android splash screen image sizes to fit all devices

Density buckets

LDPI    120dpi    .75x
MDPI    160dpi    1x
HDPI    240dpi    1.5x
XHDPI   320dpi    2x
XXHDPI  480dpi    3x
XXXHDPI 640dpi    4x

px / dp = dpi / 160 dpi

With jQuery, how do I capitalize the first letter of a text field while the user is still editing that field?

This will simply transform you first letter of text:

yourtext.substr(0,1).toUpperCase()+yourtext.substr(1);

How can I clear the NuGet package cache using the command line?

If you need to clear the NuGet cache for your build server/agent you can find the cache for NuGet packages here:

%windir%/ServiceProfiles/[account under build service runs]\AppData\Local\NuGet\Cache

Example:

C:\Windows\ServiceProfiles\NetworkService\AppData\Local\NuGet\Cache

How to cancel a local git commit

Use --soft instead of --hard flag:

git reset --soft HEAD^

How to trap the backspace key using jQuery?

try this one :

 $('html').keyup(function(e){if(e.keyCode == 8)alert('backspace trapped')})  

MS Access - execute a saved query by name in VBA

You should investigate why VBA can't find queryname.

I have a saved query named qryAddLoginfoRow. It inserts a row with the current time into my loginfo table. That query runs successfully when called by name by CurrentDb.Execute.

CurrentDb.Execute "qryAddLoginfoRow"

My guess is that either queryname is a variable holding the name of a query which doesn't exist in the current database's QueryDefs collection, or queryname is the literal name of an existing query but you didn't enclose it in quotes.

Edit: You need to find a way to accept that queryname does not exist in the current db's QueryDefs collection. Add these 2 lines to your VBA code just before the CurrentDb.Execute line.

Debug.Print "queryname = '" & queryname & "'"
Debug.Print CurrentDb.QueryDefs(queryname).Name

The second of those 2 lines will trigger run-time error 3265, "Item not found in this collection." Then go to the Immediate window to verify the name of the query you're asking CurrentDb to Execute.

Why I can't access remote Jupyter Notebook server?

Have you configured the jupyter_notebook_config.py file to allow external connections?

By default, Jupyter Notebook only accepts connections from localhost (eg, from the same computer that its running on). By modifying the NotebookApp.allow_origin option from the default ' ' to '*', you allow Jupyter to be accessed externally.

c.NotebookApp.allow_origin = '*' #allow all origins

You'll also need to change the IPs that the notebook will listen on:

c.NotebookApp.ip = '0.0.0.0' # listen on all IPs


Also see the details in a subsequent answer in this thread.

Documentation on the Jupyter Notebook config file.

Service Reference Error: Failed to generate code for the service reference

Restarting Visual Studio did the trick for me. I am using VS 2015.

How can I make a div not larger than its contents?

The answer for your question lays in the future my friend ...

namely "intrinsic" is coming with the latest CSS3 update

width: intrinsic;

unfortunately IE is behind with it so it doesn't support it yet

More about it: CSS Intrinsic & Extrinsic Sizing Module Level 3 and Can I Use?: Intrinsic & Extrinsic Sizing.

For now you have to be satisfied with <span> or <div> set to

display: inline-block;

Convert INT to DATETIME (SQL)

Try this:

select CONVERT(datetime, convert(varchar(10), 20120103))

How to clear the logs properly for a Docker container?

You can't do this directly through a Docker command.

You can either limit the log's size, or use a script to delete logs related to a container. You can find scripts examples here (read from the bottom): Feature: Ability to clear log history #1083

Check out the logging section of the docker-compose file reference, where you can specify options (such as log rotation and log size limit) for some logging drivers.

How to fix git error: RPC failed; curl 56 GnuTLS

You can set some option to resolve the issue

Either at global level: (needed if you clone, don't forget to reset after)

$ git config --global http.sslVerify false
$ git config --global http.postBuffer 1048576000

or on a local repository

$ git config http.sslVerify false
$ git config http.postBuffer 1048576000

SecurityException during executing jnlp file (Missing required Permissions manifest attribute in main jar)

If you'd like to set this globally for all users of a machine, you can create the following directory and file structures:

mkdir %windir%\Sun\Java\Deployment

Create a file deployment.config with the content:

deployment.system.config=file:///c:/windows/Sun/Java/Deployment/deployment.properties
deployment.system.config.mandatory=TRUE

Create a file deployment.properties

deployment.user.security.exception.sites=C\:/WINDOWS/Sun/Java/Deployment/exception.sites

Create a file exception.sites

http://example1.com
http://example2.com/path/to/specific/directory/

Reference https://blogs.oracle.com/java-platform-group/entry/upcoming_exception_site_list_in

JavaScript Editor Plugin for Eclipse

Think that JavaScriptDevelopmentTools might do it. Although, I have eclipse indigo, and I'm pretty sure it does that kind of thing automatically.

How can I embed a YouTube video on GitHub wiki pages?

It's not possible to embed videos directly, but you can put an image which links to a YouTube video:

[![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/YOUTUBE_VIDEO_ID_HERE/0.jpg)](https://www.youtube.com/watch?v=YOUTUBE_VIDEO_ID_HERE)

How to select some rows with specific rownames from a dataframe?

Assuming that you have a data frame called students, you can select individual rows or columns using the bracket syntax, like this:

  • students[1,2] would select row 1 and column 2, the result here would be a single cell.
  • students[1,] would select all of row 1, students[,2] would select all of column 2.

If you'd like to select multiple rows or columns, use a list of values, like this:

  • students[c(1,3,4),] would select rows 1, 3 and 4,
  • students[c("stu1", "stu2"),] would select rows named stu1 and stu2.

Hope I could help.

How to change fontFamily of TextView in Android

There is a nice library available for this

    implementation 'uk.co.chrisjenx:calligraphy:2.3.0'