Programs & Examples On #Google talk

is an XMPP based web chat service provided by Google and the name of its official client.

JavaScript, getting value of a td with id name

.innerText doesnt work in Firefox.

.innerHTML works in both the browsers.

Main differences between SOAP and RESTful web services in Java

  • REST stands for representational state transfer whereas SOAP stands for Simple Object Access Protocol.

  • SOAP defines its own security where as REST inherits security from the underlying transport.

  • SOAP does not support error handling, but REST has built-in error handling.

  • REST is lightweight and does not require XML parsing. REST can be consumed by any client, even a web browser with Ajax and JavaScript. REST consumes less bandwidth, it does not require a SOAP header for every message.

    • REST is useful over any protocol which provide a URI. Ignore point 5 for REST as mentioned below in the picture.


Get button click inside UITableViewCell

Swift 2.2

You need to add target for that button.

myButton.addTarget(self, action: #selector(ClassName.FunctionName(_:), forControlEvents: .TouchUpInside)

FunctionName: connected // for example

And of course you need to set tag of that button since you are using it.

myButton.tag = indexPath.row

You can achieve this by subclassing UITableViewCell. Use it in interface builder, drop a button on that cell, connect it via outlet and there you go.

To get the tag in the connected function:

func connected(sender: UIButton) {
    let buttonTag = sender.tag
    // Do any additional setup

How to detect escape key press with pure JS or jQuery?

The keydown event will work fine for Escape and has the benefit of allowing you to use keyCode in all browsers. Also, you need to attach the listener to document rather than the body.

Update May 2016

keyCode is now in the process of being deprecated and most modern browsers offer the key property now, although you'll still need a fallback for decent browser support for now (at time of writing the current releases of Chrome and Safari don't support it).

Update September 2018 evt.key is now supported by all modern browsers.

document.onkeydown = function(evt) {_x000D_
    evt = evt || window.event;_x000D_
    var isEscape = false;_x000D_
    if ("key" in evt) {_x000D_
        isEscape = (evt.key === "Escape" || evt.key === "Esc");_x000D_
    } else {_x000D_
        isEscape = (evt.keyCode === 27);_x000D_
    if (isEscape) {_x000D_
Click me then press the Escape key

Convert from days to milliseconds

Its important to mention that once in 4-5 years this method might give a 1 second error, becase of a leap-second (, and the correct formula for that day would be

(24*60*60 + 1) * 1000

There is a question Are leap seconds catered for by Calendar? and the answer is no.

So, if You're designing super time-dependant software, be careful about this formula.

python inserting variable string as file name

f = open('{}.csv'.format(), 'wb')

How to use index in select statement?

If you want to test the index to see if it works, here is the syntax:

FROM Table WITH(INDEX(Index_Name))

The WITH statement will force the index to be used.

ERROR 403 in loading resources like CSS and JS in my index.php

Find out the web server user

open up terminal and type lsof -i tcp:80

This will show you the user of the web server process Here is an example from a raspberry pi running debian:

apache2  7478 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)
apache2  7664 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)
apache2  7794 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)

The user is www-data

If you give ownership of the web files to the web server:

chown www-data:www-data -R /opt/lamp/htdocs

And chmod 755 for good measure:

chmod 755 -R /opt/lamp/htdocs

Let me know how you go, maybe you need to use 'sudo' before the command, i.e. sudo chown www-data:www-data -R /opt/lamp/htdocs

if it doesn't work, please give us the output of: ls -al /opt/lamp/htdocs

Aligning rotated xticklabels with their respective xticks

You can set the horizontal alignment of ticklabels, see the example below. If you imagine a rectangular box around the rotated label, which side of the rectangle do you want to be aligned with the tickpoint?

Given your description, you want: ha='right'


x = np.arange(n)
y = np.sin(np.linspace(-3,3,n))
xlabels = ['Ticklabel %i' % i for i in range(n)]

fig, axs = plt.subplots(1,3, figsize=(12,3))

ha = ['right', 'center', 'left']

for n, ax in enumerate(axs):
    ax.plot(x,y, 'o-')
    ax.set_xticklabels(xlabels, rotation=40, ha=ha[n])

enter image description here

What do two question marks together mean in C#?

Just because no-one else has said the magic words yet: it's the null coalescing operator. It's defined in section 7.12 of the C# 3.0 language specification.

It's very handy, particularly because of the way it works when it's used multiple times in an expression. An expression of the form:

a ?? b ?? c ?? d

will give the result of expression a if it's non-null, otherwise try b, otherwise try c, otherwise try d. It short-circuits at every point.

Also, if the type of d is non-nullable, the type of the whole expression is non-nullable too.

How to fill a datatable with List<T>

I also had to come up with an alternate solution, as none of the options listed here worked in my case. I was using an IEnumerable and the underlying data was a IEnumerable and the properties couldn't be enumerated. This did the trick:

// remove "this" if not on C# 3.0 / .NET 3.5
public static DataTable ConvertToDataTable<T>(this IEnumerable<T> data)
    List<IDataRecord> list = data.Cast<IDataRecord>().ToList();

    PropertyDescriptorCollection props = null;
    DataTable table = new DataTable();
    if (list != null && list.Count > 0)
        props = TypeDescriptor.GetProperties(list[0]);
        for (int i = 0; i < props.Count; i++)
            PropertyDescriptor prop = props[i];
            table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
    if (props != null)
        object[] values = new object[props.Count];
        foreach (T item in data)
            for (int i = 0; i < values.Length; i++)
                values[i] = props[i].GetValue(item) ?? DBNull.Value;
    return table;

Composer Update Laravel

this is command for composer update please try this...

composer self-update

GitHub Error Message - Permission denied (publickey)

Allow write access for the key (identity) and then click Add key

enter image description here

If on Windows check for more details in here.

How to truncate milliseconds off of a .NET DateTime

In my case, I was aiming to save TimeSpan from datetimePicker tool without saving the seconds and the milliseconds, and here is the solution.

First convert the datetimePicker.value to your desired format, which mine is "HH:mm" then convert it back to TimeSpan.

var datetime = datetimepicker1.Value.ToString("HH:mm");
TimeSpan timeSpan = Convert.ToDateTime(datetime).TimeOfDay;

How to pass parameters to a Script tag?

JQuery has a way to pass parameters from HTML to javascript:

Put this in the myhtml.html file:

<!-- Import javascript -->
<script src="//"></script>
<!-- Invoke a different javascript file called subscript.js -->
<script id="myscript" src="subscript.js" video_filename="foobar.mp4">/script>

In the same directory make a subscript.js file and put this in there:

//Use jquery to look up the tag with the id of 'myscript' above.  Get 
//the attribute called video_filename, stuff it into variable filename.
var filename = $('#myscript').attr("video_filename");

//print filename out to screen.

Analyze Result:

Loading the myhtml.html page has 'foobar.mp4' print to screen. The variable called video_filename was passed from html to javascript. Javascript printed it to screen, and it appeared as embedded into the html in the parent.

jsfiddle proof that the above works:

jquery loop on Json data using $.each

Have you converted your data from string to JavaScript object?

You can do it with data = eval('(' + string_data + ')'); or, which is safer, data = JSON.parse(string_data); but later will only works in FF 3.5 or if you include json2.js

jQuery since 1.4.1 also have function for that, $.parseJSON().

But actually, $.getJSON() should give you already parsed json object, so you should just check everything thoroughly, there is little mistake buried somewhere, like you might have forgotten to quote something in json, or one of the brackets is missing.

How to set session attribute in java?

By Java class, I am assuming you mean a Servlet class as setting session attribute in arbitrary Java class does not make sense.You can do something like this in your servlet's doGet/doPost methods

public void doGet(HttpServletRequest request, HttpServletResponse response) {

    HttpSession session = request.getSession();
    String username = (String)request.getAttribute("un");
    session.setAttribute("UserName", username);

DateTime.ToString("MM/dd/yyyy HH:mm:ss.fff") resulted in something like "09/14/2013"

You can use String.Format:

DateTime d = DateTime.Now;
string str = String.Format("{0:00}/{1:00}/{2:0000} {3:00}:{4:00}:{5:00}.{6:000}", d.Month, d.Day, d.Year, d.Hour, d.Minute, d.Second, d.Millisecond);
// I got this result: "02/23/2015 16:42:38.234"

Amazon S3 boto - how to create a folder?

With AWS SDK .Net works perfectly, just add "/" at the end of the folder name string:

var folderKey =  folderName + "/"; //end the folder name with "/"
AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client(AWSAccessKey, AWSSecretKey);
var request = new PutObjectRequest();
S3Response response = client.PutObject(request);

Then refresh your AWS console, and you will see the folder

How to get memory available or used in C#

You might want to check the GC.GetTotalMemory method.

It retrieves the number of bytes currently thought to be allocated by the garbage collector.

What’s the best RESTful method to return total number of items in an object?

You could consider counts as a resource. The URL would then be:


Using "If cell contains #N/A" as a formula condition.

Input the following formula in C1:



When #N/A:

enter image description here

When not #N/A:

enter image description here

Let us know if this helps.

How can I change NULL to 0 when getting a single value from a SQL function?



SELECT NVL(SUM(Price), 0) AS TotalPrice 
FROM Inventory
WHERE (DateAdded BETWEEN @StartDate AND @EndDate)

This SQL statement would return 0 if the SUM(Price) returned a null value. Otherwise, it would return the SUM(Price) value.

Tooltip on image

You can use the following format to generate a tooltip for an image.

<div class="tooltip"><img src="joe.jpg" />
  <span class="tooltiptext">Tooltip text</span>

Page unload event in

With AutoEventWireup which is turned on by default on a page you can just add methods prepended with **Page_***event* and have ASP.NET connect to the events for you.

In the case of Unload the method signature is:

protected void Page_Unload(object sender, EventArgs e)

For details see the MSDN article.

Get battery level and state in Android

Other answers didn't mention how to access battery status (chraging or not).

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = context.registerReceiver(null, ifilter);

// Are we charging / charged?
int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
                     status == BatteryManager.BATTERY_STATUS_FULL;

// How are we charging?
int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;

How to find a whole word in a String in java

How about something like Arrays.asList(String.split(" ")).contains("xx")?

See String.split() and How can I test if an array contains a certain value.

How to install grunt and how to build script with it

Some time we need to set PATH variable for WINDOWS


After that test with where grunt

Note: Do not forget to close the command prompt window and reopen it.

How to get database structure in MySQL via query

using this:


will give you the DDL for that table

DESCRIBE `users`

will list the columns in that table

Python "\n" tag extra line

use join(), don't rely on the , for formatting, and also print automatically puts the cursor on a newline every time, so no need of adding another '\n' in your print.

In [24]: for x in board:
    print " ".join(map(str,x))
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 3 2 1 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0

#ifdef replacement in the Swift language

func inDebugBuilds(_ code: () -> Void) {
    assert({ code(); return true }())


how to list all sub directories in a directory

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

namespace TRIAL
    public class Class1
        static void Main(string[] args)
           string[] fileArray = Directory.GetDirectories("YOUR PATH");
           for (int i = 0; i < fileArray.Length; i++)


What is Hive: Return Code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask

I was also facing same error when I was inserting the data into HIVE external table which was pointing to Elastic search cluster.

I replaced the older JAR elasticsearch-hadoop-2.0.0.RC1.jar to elasticsearch-hadoop-5.6.0.jar, and everything worked fine.

My Suggestion is please use the specific JAR as per the elastic search version. Don't use older JARs if you are using newer version of elastic search.

Thanks to this post Hive- Elasticsearch Write Operation #409

ASP.NET Background image

Just a heads up, while some of the answers posted here are correct (in a sense) one thing that you may need to do is go back to the root folder to delve down into the folder holding the image you want to set as the background. In other words, this code is correct in accomplishing your goal:

body {

But you may also need to add a little more to the code, like this:

body {

The difference, as you can see, is that you may need to add “../” in front of the “images/background.png” call. This same rule also applies in HTML5 web pages. So if you are trying the first sample code listed here and you are still not getting the background image, try adding the “../” in front of “images”. Hope this helps .

add allow_url_fopen to my php.ini using .htaccess

allow_url_fopen is generally set to On. If it is not On, then you can try two things.

  1. Create an .htaccess file and keep it in root folder ( sometimes it may need to place it one step back folder of the root) and paste this code there.

    php_value allow_url_fopen On
  2. Create a php.ini file (for update server php5.ini) and keep it in root folder (sometimes it may need to place it one step back folder of the root) and paste the following code there:

    allow_url_fopen = On;

I have personally tested the above solutions; they worked for me.

What difference between the DATE, TIME, DATETIME, and TIMESTAMP Types

I have a slightly different perspective on the difference between a DATETIME and a TIMESTAMP. A DATETIME stores a literal value of a date and time with no reference to any particular timezone. So, I can set a DATETIME column to a value such as '2019-01-16 12:15:00' to indicate precisely when my last birthday occurred. Was this Eastern Standard Time? Pacific Standard Time? Who knows? Where the current session time zone of the server comes into play occurs when you set a DATETIME column to some value such as NOW(). The value stored will be the current date and time using the current session time zone in effect. But once a DATETIME column has been set, it will display the same regardless of what the current session time zone is.

A TIMESTAMP column on the other hand takes the '2019-01-16 12:15:00' value you are setting into it and interprets it in the current session time zone to compute an internal representation relative to 1/1/1970 00:00:00 UTC. When the column is displayed, it will be converted back for display based on whatever the current session time zone is. It's a useful fiction to think of a TIMESTAMP as taking the value you are setting and converting it from the current session time zone to UTC for storing and then converting it back to the current session time zone for displaying.

If my server is in San Francisco but I am running an event in New York that starts on 9/1/1029 at 20:00, I would use a TIMESTAMP column for holding the start time, set the session time zone to 'America/New York' and set the start time to '2009-09-01 20:00:00'. If I want to know whether the event has occurred or not, regardless of the current session time zone setting I can compare the start time with NOW(). Of course, for displaying in a meaningful way to a perspective customer, I would need to set the correct session time zone. If I did not need to do time comparisons, then I would probably be better off just using a DATETIME column, which will display correctly (with an implied EST time zone) regardless of what the current session time zone is.


The TIMESTAMP type has a range of '1970-01-01 00:00:01' UTC to '2038-01-19 03:14:07' UTC and so it may not usable for your particular application. In that case you will have to use a DATETIME type. You will, of course, always have to be concerned that the current session time zone is set properly whenever you are using this type with date functions such as NOW().

Pointers, smart pointers or shared pointers?

To add a small bit to Sydius' answer, smart pointers will often provide a more stable solution by catching many easy to make errors. Raw pointers will have some perfromance advantages and can be more flexible in certain circumstances. You may also be forced to use raw pointers when linking into certain 3rd party libraries.

Write HTML file using Java

if it is becoming repetitive work ; i think you shud do code reuse ! why dont you simply write functions that "write" small building blocks of HTML. get the idea? see Eg. you can have a function to which you could pass a string and it would automatically put that into a paragraph tag and present it. Of course you would also need to write some kind of a basic parser to do this (how would the function know where to attach the paragraph!). i dont think you are a beginner .. so i am not elaborating ... do tell me if you do not understand..

Regex to extract URLs from href attribute in HTML with Python

import re

url = '<p>Hello World</p><a href="">More Examples</a><a href="">Even More Examples</a>'

urls = re.findall('https?://(?:[-\w.]|(?:%[\da-fA-F]{2}))+', url)

>>> print urls
['', '']

Setting up maven dependency for SQL Server


This worked for me(if you use maven)

Visual Studio 2015 Update 3 Offline Installer (ISO)

Its better to go through the Recommended Microsoft's Way to download Visual Studio 2015 Update 3 ISO (Community Edition).

The instructions below will help you to download any version of Visual Studio or even SQL Server etc provided by Microsoft in an easy to remember way. Though I recommend people using VS 2017 as there are not much big differences between 2015 and 2017.

Please follow the steps as mentioned below.

  1. Visit the standard URL

  2. Scroll down and click on encircled below as shown in snapshot down Snapshot showing how to download older visual studio versions

  3. After that join Visual Studio Web Dev essentials for Free as shown below. Try loggin in with your microsoft account and see that if it works otherwise click on Joinenter image description here

  4. Click on Downloads ICON on the encircled as shown below. enter image description here

  5. Now Type Visual Studio Community in the Search Box as shown below in the snapshot enter image description here.
  6. From the drowdown select the DVD type and start downloading enter image description here

CASE statement in SQLite query

Also, you do not have to use nested CASEs. You can use several WHEN-THEN lines and the ELSE line is also optional eventhough I recomend it

   WHEN [condition.1] THEN [expression.1]
   WHEN [condition.2] THEN [expression.2]
   WHEN [condition.n] THEN [expression.n]
   ELSE [expression] 

Hadoop: «ERROR : JAVA_HOME is not set»

In some distributives(CentOS/OpenSuSe,...) will work only if you set JAVA_HOME in the /etc/environment.

PDO with INSERT INTO through prepared statements

Please add try catch also in your code so that you can be sure that there in no exception.

try {
    $hostname = "servername";
    $dbname = "dbname";
    $username = "username";
    $pw = "password";
    $pdo = new PDO ("mssql:host=$hostname;dbname=$dbname","$username","$pw");
  } catch (PDOException $e) {
    echo "Failed to get DB handle: " . $e->getMessage() . "\n";

Nullable property to entity field, Entity Framework through Code First

The other option is to tell EF to allow the column to be null:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
        modelBuilder.Entity<SomeObject>().Property(m => m.somefield).IsOptional();            

This code should be in the object that inherits from DbContext.

How to get a barplot with several variables side by side grouped by a factor

Using reshape2 and dplyr. Your data:

df <- read.table(text=
"tea                coke            beer             water           gender
14.55              26.50793651     22.53968254      40              1
24.92997199        24.50980392     26.05042017      24.50980393     2
23.03732304        30.63063063     25.41827542      20.91377091     1   
225.51781276       24.6064623      24.85501243      50.80645161     1
24.53662842        26.03706973     25.24271845      24.18358341     2", header=TRUE)

Getting data into correct form:

df.melt <- melt(df, id="gender")
bar <- group_by(df.melt, variable, gender)%.%summarise(mean=mean(value))


ggplot(bar, aes(x=variable, y=mean, fill=factor(gender)))+
  geom_bar(position="dodge", stat="identity")

enter image description here

DataTables: Uncaught TypeError: Cannot read property 'defaults' of undefined

<script src=""defer</script>

Add Defer to the end of your Script tag, it worked for me (;

Everything needs to be loaded in the correct order (:

What is dtype('O'), in pandas?

It means "a python object", i.e. not one of the builtin scalar types supported by numpy.

=> dtype('O')

Rewrite URL after redirecting 404 error htaccess

Try adding this rule to the top of your htaccess:

RewriteEngine On
RewriteRule ^404/?$ /pages/errors/404.php [L]

Then under that (or any other rules that you have):

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^ [L,R]

Why is HttpContext.Current null?

try to implement Application_AuthenticateRequest instead of Application_Start.

this method has an instance for HttpContext.Current, unlike Application_Start (which fires very soon in app lifecycle, soon enough to not hold a HttpContext.Current object yet).

hope that helps.

How to pass parameters on onChange of html select

You can try bellow code

<select onchange="myfunction($(this).val())" id="myId">

How to subtract X days from a date using Java calendar?

tl;dr 10 )

Better to specify time zone. ZoneId.of( "America/Montreal" ) ).minusDays( 10 )


The old date-time classes bundled with early versions of Java, such as java.util.Date/.Calendar, have proven to be troublesome, confusing, and flawed. Avoid them.


Java 8 and later supplants those old classes with the new java.time framework. See Tutorial. Defined by JSR 310, inspired by Joda-Time, and extended by theThreeTen-Extra project. The ThreeTen-Backport project back-ports the classes to Java 6 & 7; the ThreeTenABP project to Android.

The Question is vague, not clear if it asks for a date-only or a date-time.


For a date-only, without time-of-day, use the LocalDate class. Note that a time zone in crucial in determining a date such as "today".

LocalDate today = ZoneId.of( "America/Montreal" ) );
LocalDate tenDaysAgo = today.minusDays( 10 );


If you meant a date-time, then use the Instant class to get a moment on the timeline in UTC. From there, adjust to a time zone to get a ZonedDateTime object.

Instant now =;  // UTC.
ZoneId zoneId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );
ZonedDateTime tenDaysAgo = zdt.minusDays( 10 );

Table of date-time types in Java, both modern and legacy.

About java.time

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

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

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

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

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

How (and why) to use display: table-cell (CSS)

After days trying to find the answer, I finally found

display: table;

There was surprisingly very little information available online about how to actually getting it to work, even here, so on to the "How":

To use this fantastic piece of code, you need to think back to when tables were the only real way to structure HTML, namely the syntax. To get a table with 2 rows and 3 columns, you'd have to do the following:


Similarly to get CSS to do it, you'd use the following:


<div id="table">
    <div class="tr">
        <div class="td"></div>
        <div class="td"></div>
        <div class="td"></div>
    <div class="tr">
        <div class="td"></div>
        <div class="td"></div>
        <div class="td"></div>


    display: table; 
    display: table-row; 
    display: table-cell; }

As you can see in the JSFiddle example below, the divs in the 3rd column have no content, yet are respecting the auto height set by the text in the first 2 columns. WIN!

It's worth noting that display: table; does not work in IE6 or 7 (thanks, FelipeAls), so depending on your needs with regards to browser compatibility, this may not be the answer that you are seeking.

Increment a Integer's int value?

Maybe you can try:

final AtomicInteger i = new AtomicInteger(0);

an attempt was made to access a socket in a way forbbiden by its access permissions. why?

Well I don't even understand the culprit of this problem. But in my case the problem is totally different. I've tried running netstat -o or netstat -ab, both show that there is not any app currently listening on port 62434 which is the one my app tries to listen on. So it's really confusing to me.

I just tried thinking of what I had made so that it stopped working (it did work before). Well then I thought of the Internet sharing I made on my Ethernet adapter with a private virtual LAN (using Hyper-v in Windows 10). I just needed to turn off the sharing and it worked just fine again.

Hope this helps someone else having the same issue. And of course if someone could explain this, please add more detail in your own answer or maybe as some comment to my answer.

Run parallel multiple commands at once in the same terminal

Based on comment of @alessandro-pezzato. Run multiples commands by using & between the commands.


$ sleep 3 & sleep 5 & sleep 2 &

It's will execute the commands in background.

sql server #region

No, #region does not exist in the T-SQL language.

You can get code-folding using begin-end blocks:

-- my region
    -- code goes here

I'm not sure I'd recommend using them for this unless the code cannot be acceptably refactored by other means though!

remove kernel on jupyter notebook

Run jupyter kernelspec list to get the paths of all your kernels.
Then simply uninstall your unwanted-kernel

jupyter kernelspec uninstall unwanted-kernel

Old answer
Delete the folder corresponding to the kernel you want to remove.

The docs has a list of the common paths for kernels to be stored in:

When to use malloc for char pointers

malloc is for allocating memory on the free-store. If you have a string literal that you do not want to modify the following is ok:

char *literal = "foo";

However, if you want to be able to modify it, use it as a buffer to hold a line of input and so on, use malloc:

char *buf = (char*) malloc(BUFSIZE); /* define BUFSIZE before */
// ...

Text file with 0D 0D 0A line breaks

Just saying, this is also the value (kind of...) that is returned from php upon:

<?php var_dump(urlencode(PHP_EOL)); ?> 
    // Prints: string '%0D%0A' (length=6)-- used in 5.4.24 at least

Sending GET request with Authentication headers using restTemplate

All of these answers appear to be incomplete and/or kludges. Looking at the RestTemplate interface, it sure looks like it is intended to have a ClientHttpRequestFactory injected into it, and then that requestFactory will be used to create the request, including any customizations of headers, body, and request params.

You either need a universal ClientHttpRequestFactory to inject into a single shared RestTemplate or else you need to get a new template instance via new RestTemplate(myHttpRequestFactory).

Unfortunately, it looks somewhat non-trivial to create such a factory, even when you just want to set a single Authorization header, which is pretty frustrating considering what a common requirement that likely is, but at least it allows easy use if, for example, your Authorization header can be created from data contained in a Spring-Security Authorization object, then you can create a factory that sets the outgoing AuthorizationHeader on every request by doing SecurityContextHolder.getContext().getAuthorization() and then populating the header, with null checks as appropriate. Now all outbound rest calls made with that RestTemplate will have the correct Authorization header.

Without more emphasis placed on the HttpClientFactory mechanism, providing simple-to-overload base classes for common cases like adding a single header to requests, most of the nice convenience methods of RestTemplate end up being a waste of time, since they can only rarely be used.

I'd like to see something simple like this made available

public class MyConfig {
  public RestTemplate getRestTemplate() {
    return new RestTemplate(new AbstractHeaderRewritingHttpClientFactory() {
        public HttpHeaders modifyHeaders(HttpHeaders headers) {
          headers.addHeader("Authorization", computeAuthString());
          return headers;
        public String computeAuthString() {
          // do something better than this, but you get the idea
          return SecurityContextHolder.getContext().getAuthorization().getCredential();

At the moment, the interface of the available ClientHttpRequestFactory's are harder to interact with than that. Even better would be an abstract wrapper for existing factory implementations which makes them look like a simpler object like AbstractHeaderRewritingRequestFactory for the purposes of replacing just that one piece of functionality. Right now, they are very general purpose such that even writing those wrappers is a complex piece of research.

Powershell script to check if service is started, if not then start it

Given $arrService = Get-Service -Name $ServiceName, $arrService.Status is a static property, corresponding to the value at the time of the call. Use $arrService.Refresh() when needed to renew the properties to current values.

MSDN ~ ServiceController.Refresh()

Refreshes property values by resetting the properties to their current values.

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

I think I encountered the same problem as you. I addressed this problem with the following steps:

1) Go to Google Developers Console

2) Set JavaScript origins:

3) Set Redirect URIs:

HTML Table cellspacing or padding just top / bottom

Cellspacing is all around the cell and cannot be changed (i.e. if it's set to one, there will be 1 pixel of space on all sides). Padding can be specified discreetly (e.g. padding-top, padding-bottom, padding-left, and padding-right; or padding: [top] [right] [bottom] [left];).

Selecting distinct values from a JSON

Give this a go:

var distinct_list 

  = (d) {return d[x];}).filter((v, i, a) => a.indexOf(v) === i)

Laravel - display a PDF file in storage without forcing download?

Since Laravel 5.2 you can use File Responses
Basically you can call it like this:

return response()->file($pathToFile);

and it will display files as PDF and images inline in the browser.

Android: how to handle button click

My sample, Tested in Android studio 2.1

Define button in xml layout

    android:layout_height="wrap_content" />

Java pulsation detect

Button clickButton = (Button) findViewById(;
if (clickButton != null) {
    clickButton.setOnClickListener( new View.OnClickListener() {

        public void onClick(View v) {
            /***Do what you want with the click here***/

Add my custom http header to Spring RestTemplate request / extend RestTemplate

Here's a method I wrote to check if an URL exists or not. I had a requirement to add a request header. It's Groovy but should be fairly simple to adapt to Java. Essentially I'm using the org.springframework.web.client.RestTemplate#execute(java.lang.String, org.springframework.http.HttpMethod, org.springframework.web.client.RequestCallback, org.springframework.web.client.ResponseExtractor<T>, java.lang.Object...) API method. I guess the solution you arrive at depends at least in part on the HTTP method you want to execute. The key take away from example below is that I'm passing a Groovy closure (The third parameter to method restTemplate.execute(), which is more or less, loosely speaking a Lambda in Java world) that is executed by the Spring API as a callback to be able to manipulate the request object before Spring executes the command,

boolean isUrlExists(String url) {
    try {
      return (restTemplate.execute(url, HttpMethod.HEAD,
              { ClientHttpRequest request -> request.headers.add('header-name', 'header-value') },
              { ClientHttpResponse response -> response.headers }) as HttpHeaders)?.get('some-response-header-name')?.contains('some-response-header-value')
    } catch (Exception e) {
      log.warn("Problem checking if $url exists", e)

object==null or null==object?

This is not of much value in Java (1.5+) except when the type of object is Boolean. In which case, this can still be handy.

if (object = null) will not cause compilation failure in Java 1.5+ if object is Boolean but would throw a NullPointerException at runtime.

Random integer in VB.NET

Use System.Random:

Dim MyMin As Integer = 1, MyMax As Integer = 5, My1stRandomNumber As Integer, My2ndRandomNumber As Integer

' Create a random number generator
Dim Generator As System.Random = New System.Random()

' Get a random number >= MyMin and <= MyMax
My1stRandomNumber = Generator.Next(MyMin, MyMax + 1) ' Note: Next function returns numbers _less than_ max, so pass in max + 1 to include max as a possible value

' Get another random number (don't create a new generator, use the same one)
My2ndRandomNumber = Generator.Next(MyMin, MyMax + 1)

Python: How to get values of an array at certain index positions?

Although you ask about numpy arrays, you can get the same behavior for regular Python lists by using operator.itemgetter.

>>> from operator import itemgetter
>>> a = [0,88,26,3,48,85,65,16,97,83,91]
>>> ind_pos = [1, 5, 7]
>>> print itemgetter(*ind_pos)(a)
(88, 85, 16)

How to disable and then enable onclick event on <div> with javascript

To enable use bind() method


call this handler

 function  eventhandler(){
      alert("Bind click")

To disable click useunbind()


ActiveRecord find and only return selected columns

In Rails 2

l = Location.find(:id => id, :select => "name, website, city", :limit => 1)


l = Location.find_by_sql(:conditions => ["SELECT name, website, city FROM locations WHERE id = ? LIMIT 1", id])

This reference doc gives you the entire list of options you can use with .find, including how to limit by number, id, or any other arbitrary column/constraint.

In Rails 3 w/ActiveRecord Query Interface

l = Location.where(["id = ?", id]).select("name, website, city").first

Ref: Active Record Query Interface

You can also swap the order of these chained calls, doing .select(...).where(...).first - all these calls do is construct the SQL query and then send it off.

Python re.sub replace with matched content

A backreference to the whole match value is \g<0>, see re.sub documentation:

The backreference \g<0> substitutes in the entire substring matched by the RE.

See the Python demo:

import re
method = 'images/:id/huge'
print(re.sub(r':[a-z]+', r'<span>\g<0></span>', method))
# => images/<span>:id</span>/huge

Using PropertyInfo.GetValue()

In your example propertyInfo.GetValue(this, null) should work. Consider altering GetNamesAndTypesAndValues() as follows:

public void GetNamesAndTypesAndValues()
  foreach (PropertyInfo propertyInfo in allClassProperties)
    Console.WriteLine("{0} [type = {1}] [value = {2}]",
      propertyInfo.GetValue(this, null));

how to use "AND", "OR" for RewriteCond on Apache?

This is an interesting question and since it isn't explained very explicitly in the documentation I'll answer this by going through the sourcecode of mod_rewrite; demonstrating a big benefit of open-source.

In the top section you'll quickly spot the defines used to name these flags:

#define CONDFLAG_NONE               1<<0
#define CONDFLAG_NOCASE             1<<1
#define CONDFLAG_NOTMATCH           1<<2
#define CONDFLAG_ORNEXT             1<<3
#define CONDFLAG_NOVARY             1<<4

and searching for CONDFLAG_ORNEXT confirms that it is used based on the existence of the [OR] flag:

else if (   strcasecmp(key, "ornext") == 0
         || strcasecmp(key, "OR") == 0    ) {
    cfg->flags |= CONDFLAG_ORNEXT;

The next occurrence of the flag is the actual implementation where you'll find the loop that goes through all the RewriteConditions a RewriteRule has, and what it basically does is (stripped, comments added for clarity):

# loop through all Conditions that precede this Rule
for (i = 0; i < rewriteconds->nelts; ++i) {
    rewritecond_entry *c = &conds[i];

    # execute the current Condition, see if it matches
    rc = apply_rewrite_cond(c, ctx);

    # does this Condition have an 'OR' flag?
    if (c->flags & CONDFLAG_ORNEXT) {
        if (!rc) {
            /* One condition is false, but another can be still true. */
        else {
            /* skip the rest of the chained OR conditions */
            while (   i < rewriteconds->nelts
                   && c->flags & CONDFLAG_ORNEXT) {
                c = &conds[++i];
    else if (!rc) {
        return 0;

You should be able to interpret this; it means that OR has a higher precedence, and your example indeed leads to if ( (A OR B) AND (C OR D) ). If you would, for example, have these Conditions:

RewriteCond A [or]
RewriteCond B [or]
RewriteCond C
RewriteCond D

it would be interpreted as if ( (A OR B OR C) and D ).

Python map object is not subscriptable

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:

Can Powershell Run Commands in Parallel?

This has been answered thoroughly. Just want to post this method i have created based on Powershell-Jobs as a reference.

Jobs are passed on as a list of script-blocks. They can be parameterized. Output of the jobs is color-coded and prefixed with a job-index (just like in a vs-build-process, as this will be used in a build) Can be used to startup multiple servers at a time or running build steps in parallel or so..

function Start-Parallel {
        [Parameter(Position = 0)]


    $jobs = $ScriptBlock | ForEach-Object { Start-Job -ScriptBlock $_ -ArgumentList $parameters }
    $colors = "Blue", "Red", "Cyan", "Green", "Magenta"
    $colorCount = $colors.Length

    try {
        while (($jobs | Where-Object { $_.State -ieq "running" } | Measure-Object).Count -gt 0) {
            $jobs | ForEach-Object { $i = 1 } {
                $fgColor = $colors[($i - 1) % $colorCount]
                $out = $_ | Receive-Job
                $out = $out -split [System.Environment]::NewLine
                $out | ForEach-Object {
                    Write-Host "$i> "-NoNewline -ForegroundColor $fgColor
                    Write-Host $_
    } finally {
        Write-Host "Stopping Parallel Jobs ..." -NoNewline
        $jobs | Stop-Job
        $jobs | Remove-Job -Force
        Write-Host " done."

sample output:

sample output

Which ORM should I use for Node.js and MySQL?

One major difference between Sequelize and Persistence.js is that the former supports a STRING datatype, i.e. VARCHAR(255). I felt really uncomfortable making everything TEXT.

How can I make my own event in C#?

You can declare an event with the following code:

public event EventHandler MyOwnEvent;

A custom delegate type instead of EventHandler can be used if needed.

You can find detailed information/tutorials on the use of events in .NET in the article Events Tutorial (MSDN).

What is difference between png8 and png24

There is only one PNG format, but it supports 5 color types.

PNG-8 refers to palette variant, which supports only 256 colors, but is usually smaller in size. PNG-8 can be a GIF substitute.

PNG-24 refers to true color variant, which supports more colors, but might be bigger. PNG-24 can be used instead of JPEG, if lossless image format is needed.

Any modern web browser will support both variants.

Force overwrite of local file with what's in origin repo?

I believe what you are looking for is "git restore".

The easiest way is to remove the file locally, and then execute the git restore command for that file:

$ rm file.txt
$ git restore file.txt 

Twitter Bootstrap - full width navbar

I know I'm a bit late to the party, but I got around the issue by tweaking the CSS to have the width span 100%, and setting l/r margins to 0px;

    margin-left: 0px;
    margin-right: 0px;
    width: 100%;

Random state (Pseudo-random number) in Scikit learn

If you don't specify the random_state in your code, then every time you run(execute) your code a new random value is generated and the train and test datasets would have different values each time.

However, if a fixed value is assigned like random_state = 42 then no matter how many times you execute your code the result would be the same .i.e, same values in train and test datasets.

Passing a varchar full of comma delimited values to a SQL Server IN function

I have same idea with user KM. but do not need extra table Number. Just this function only.

CREATE FUNCTION [dbo].[FN_ListToTable]
    @SplitOn              char(1)              --REQUIRED, the character to split the @List string on
   ,@List                 varchar(8000)        --REQUIRED, the list to split apart
@ParsedList table
    ListValue varchar(500)
    DECLARE @number int = 0
    DECLARE @childString varchar(502) = ''
    DECLARE @lengthChildString int = 0
    DECLARE @processString varchar(502) = @SplitOn + @List + @SplitOn

    WHILE @number < LEN(@processString)
        SET @number = @number + 1
        SET @lengthChildString = CHARINDEX(@SplitOn, @processString, @number + 1) - @number - 1
        IF @lengthChildString > 0
            SET @childString = LTRIM(RTRIM(SUBSTRING(@processString, @number + 1, @lengthChildString)))

            IF @childString IS NOT NULL AND @childString != ''
                INSERT INTO @ParsedList(ListValue) VALUES (@childString)
                SET @number = @number + @lengthChildString - 1



And here is the test:

SELECT ListValue FROM dbo.FN_ListToTable('/','a/////bb/c')



jQuery append text inside of an existing paragraph tag

I have just discovered a way to append text and its working fine at least.

 var text = 'Put any text here';

You can change text according to your need.

Hope this helps.

OR, AND Operator

If what interests you is bitwise operations look here for a brief tutorial : .bitwise operation perform the same operations like the ones exemplified above they just work with binary representation (the operation applies to each individual bit of the value)

If you want logical operation answers are already given.

Obtain form input fields using jQuery?

This piece of code will work instead of name, email enter your form fields name

    var name = $("input[name='name']",this).val();
    var email = $("input[name='email']",this).val();

node and Error: EMFILE, too many open files

I ran into this problem today, and finding no good solutions for it, I created a module to address it. I was inspired by @fbartho's snippet, but wanted to avoid overwriting the fs module.

The module I wrote is Filequeue, and you use it just like fs:

var Filequeue = require('filequeue');
var fq = new Filequeue(200); // max number of files to open at once

fq.readdir('/Users/xaver/Downloads/xaver/xxx/xxx/', function(err, files) {
    if(err) {
        throw err;
    files.forEach(function(file) {
        fq.readFile('/Users/xaver/Downloads/xaver/xxx/xxx/' + file, function(err, data) {
            // do something here

Why do package names often begin with "com"

It's the domain name spelt out in reverse.

For example, one of my domains is So, I use com.hedgee as the base name of all my packages.

How to close off a Git Branch?

after complete the code first merge branch to master then delete that branch

git checkout master
git merge <branch-name>
git branch -d <branch-name>

How to float a div over Google Maps?

absolute positioning is evil... this solution doesn't take into account window size. If you resize the browser window, your div will be out of place!

Python __call__ special method practical example

This is too late but I'm giving an example. Imagine you have a Vector class and a Point class. Both take x, y as positional args. Let's imagine you want to create a function that moves the point to be put on the vector.

4 Solutions

  • put_point_on_vec(point, vec)

  • Make it a method on the vector class. e.g my_vec.put_point(point)

  • Make it a method on the Point class. my_point.put_on_vec(vec)
  • Vector implements __call__, So you can use it like my_vec_instance(point)

This is actually part of some examples I'm working on for a guide for dunder methods explained with Maths that I'm gonna release sooner or later.

I left the logic of moving the point itself because this is not what this question is about

Access to the path is denied

I was having the same problem while trying to create a file on the server (actually a file that is a copy from a template).

Here's the complete error message:

{ERROR} 08/07/2012 22:15:58 - System.UnauthorizedAccessException: Access to the path 'C:\inetpub\wwwroot\SAvE\Templates\Cover.pdf' is denied.

I added a new folder called Templates inside the IIS app folder. One very important thing in my case is that I needed to give the Write (Gravar) permission for the IUSR user on that folder. You may also need to give Network Service and ASP.NET v$.# the same Write permission.

enter image description here

After doing this everything works as expected.

Java: Replace all ' in a string with \'

This doesn't say how to "fix" the problem - that's already been done in other answers; it exists to draw out the details and applicable documentation references.

When using String.replaceAll or any of the applicable Matcher replacers, pay attention to the replacement string and how it is handled:

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string. Dollar signs may be treated as references to captured subsequences as described above, and backslashes are used to escape literal characters in the replacement string.

As pointed out by isnot2bad in a comment, Matcher.quoteReplacement may be useful here:

Returns a literal replacement String for the specified String. .. The String produced will match the sequence of characters in s treated as a literal sequence. Slashes (\) and dollar signs ($) will be given no special meaning.

Configure Apache .conf for Alias

Sorry not sure what was going on this worked in the end:

<VirtualHost *> 
    DocumentRoot /var/www/html/mjp

    Alias /ncn "/var/www/html/ncn"

    <Directory "/var/www/html/ncn">
        Options None
        AllowOverride None
        Order allow,deny
        Allow from all

PyLint "Unable to import" error - how to set PYTHONPATH?


if __name__ == '__main__':
    from [whatever the name of your package is] import one
    import one

Note that in Python 3, the syntax for the part in the else clause would be

from .. import one

On second thought, this probably won't fix your specific problem. I misunderstood the question and thought that was being run as the main module, but that is not the case. And considering the differences in the way Python 2.6 (without importing absolute_import from __future__) and Python 3.x handle imports, you wouldn't need to do this for Python 2.6 anyway, I don't think.

Still, if you do eventually switch to Python 3 and plan on using a module as both a package module and as a standalone script inside the package, it may be a good idea to keep something like

if __name__ == '__main__':
    from [whatever the name of your package is] import one   # assuming the package is in the current working directory or a subdirectory of PYTHONPATH
    from .. import one

in mind.

EDIT: And now for a possible solution to your actual problem. Either run PyLint from the directory containing your one module (via the command line, perhaps), or put the following code somewhere when running PyLint:

import os

olddir = os.getcwd()
import one

Basically, as an alternative to fiddling with PYTHONPATH, just make sure the current working directory is the directory containing when you do the import.

(Looking at Brian's answer, you could probably assign the previous code to init_hook, but if you're going to do that then you could simply do the appending to sys.path that he does, which is slightly more elegant than my solution.)

What is the difference between Html.Hidden and Html.HiddenFor

Every method in HtmlHelper class has a twin with For suffix. Html.Hidden takes a string as an argument that you must provide but Html.HiddenFor takes an Expression that if you view is a strongly typed view you can benefit from this and feed that method a lambda expression like this


instead of "SomeProperty" in the case of using Html.Hidden method.

Batch script to delete files

Consider that the files you need to delete have an extension txt and is located in the location D:\My Folder, then you could use the below code inside the bat file.

cd "D:\My Folder"
DEL *.txt 

how to create Socket connection in Android?

Here, in this post you will find the detailed code for establishing socket between devices or between two application in the same mobile.

You have to create two application to test below code.

In both application's manifest file, add below permission

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

1st App code: Client Socket


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

<RelativeLayout xmlns:android=""


            android:hint="Enter message"
            android:inputType="text" />

            android:text="Send" />


            android:orientation="vertical" />

import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


 * Created by Girish Bhalerao on 5/4/2017.
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView mTextViewReplyFromServer;
    private EditText mEditTextSendMessage;

    protected void onCreate(Bundle savedInstanceState) {

        Button buttonSend = (Button) findViewById(;

        mEditTextSendMessage = (EditText) findViewById(;
        mTextViewReplyFromServer = (TextView) findViewById(;


    public void onClick(View v) {

        switch (v.getId()) {


    private void sendMessage(final String msg) {

        final Handler handler = new Handler();
        Thread thread = new Thread(new Runnable() {
            public void run() {

                try {
                    //Replace below IP with the IP of that device in which server socket open.
                    //If you change port then change the port number in the server side code also.
                    Socket s = new Socket("", 9002);

                    OutputStream out = s.getOutputStream();

                    PrintWriter output = new PrintWriter(out);

                    BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
                    final String st = input.readLine();

           Runnable() {
                        public void run() {

                            String s = mTextViewReplyFromServer.getText().toString();
                            if (st.trim().length() != 0)
                                mTextViewReplyFromServer.setText(s + "\nFrom Server : " + st);

                } catch (IOException e) {


2nd App Code - Server Socket


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

        android:text="STOP Receiving data"
        android:layout_marginTop="89dp" />


            android:orientation="vertical" />

        android:text="START Receiving data"
        android:layout_marginTop="14dp" />

import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


 * Created by Girish Bhalerao on 5/4/2017.
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    final Handler handler = new Handler();

    private Button buttonStartReceiving;
    private Button buttonStopReceiving;
    private TextView textViewDataFromClient;
    private boolean end = false;

    protected void onCreate(Bundle savedInstanceState) {

        buttonStartReceiving = (Button) findViewById(;
        buttonStopReceiving = (Button) findViewById(;
        textViewDataFromClient = (TextView) findViewById(;



    private void startServerSocket() {

        Thread thread = new Thread(new Runnable() {

            private String stringData = null;

            public void run() {

                try {

                    ServerSocket ss = new ServerSocket(9002);

                    while (!end) {
                        //Server is waiting for client here, if needed
                        Socket s = ss.accept();
                        BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
                        PrintWriter output = new PrintWriter(s.getOutputStream());

                        stringData = input.readLine();
                        output.println("FROM SERVER - " + stringData.toUpperCase());

                        try {
                        } catch (InterruptedException e) {
                        if (stringData.equalsIgnoreCase("STOP")) {
                            end = true;

                } catch (IOException e) {


    private void updateUI(final String stringData) { Runnable() {
            public void run() {

                String s = textViewDataFromClient.getText().toString();
                if (stringData.trim().length() != 0)
                    textViewDataFromClient.setText(s + "\n" + "From Client : " + stringData);

    public void onClick(View v) {

        switch (v.getId()) {



                //stopping server socket logic you can add yourself

Android Studio - Emulator - eglSurfaceAttrib not implemented

I've found the same thing, but only on emulators that have the Use Host GPU setting ticked. Try turning that off, you'll no longer see those warnings (and the emulator will run horribly, horribly slowly..)

In my experience those warnings are harmless. Notice that the "error" is EGL_SUCCESS, which would seem to indicate no error at all!

How to list all databases in the mongo shell?

For MongoDB shell version 3.0.5 insert the following command in the shell:


or alternatively:


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
    // 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)


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):

    // 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));
            return oldJSONStringify(input);

jsFiddle with example here

js Performance test here, via jsPerf

OPTION (RECOMPILE) is Always Faster; Why?

There are times that using OPTION(RECOMPILE) makes sense. In my experience the only time this is a viable option is when you are using dynamic SQL. Before you explore whether this makes sense in your situation I would recommend rebuilding your statistics. This can be done by running the following:

EXEC sp_updatestats

And then recreating your execution plan. This will ensure that when your execution plan is created it will be using the latest information.

Adding OPTION(RECOMPILE) rebuilds the execution plan every time that your query executes. I have never heard that described as creates a new lookup strategy but maybe we are just using different terms for the same thing.

When a stored procedure is created (I suspect you are calling ad-hoc sql from .NET but if you are using a parameterized query then this ends up being a stored proc call) SQL Server attempts to determine the most effective execution plan for this query based on the data in your database and the parameters passed in (parameter sniffing), and then caches this plan. This means that if you create the query where there are 10 records in your database and then execute it when there are 100,000,000 records the cached execution plan may no longer be the most effective.

In summary - I don't see any reason that OPTION(RECOMPILE) would be a benefit here. I suspect you just need to update your statistics and your execution plan. Rebuilding statistics can be an essential part of DBA work depending on your situation. If you are still having problems after updating your stats, I would suggest posting both execution plans.

And to answer your question - yes, I would say it is highly unusual for your best option to be recompiling the execution plan every time you execute the query.

Return array from function

At a minimum, change this:

function BlockID() {
    var IDs = new Array();
        images['s'] = "Images/Block_01.png";
        images['g'] = "Images/Block_02.png";
        images['C'] = "Images/Block_03.png";
        images['d'] = "Images/Block_04.png";
    return IDs;

To this:

function BlockID() {
    var IDs = new Object();
        IDs['s'] = "Images/Block_01.png";
        IDs['g'] = "Images/Block_02.png";
        IDs['C'] = "Images/Block_03.png";
        IDs['d'] = "Images/Block_04.png";
    return IDs;

There are a couple fixes to point out. First, images is not defined in your original function, so assigning property values to it will throw an error. We correct that by changing images to IDs. Second, you want to return an Object, not an Array. An object can be assigned property values akin to an associative array or hash -- an array cannot. So we change the declaration of var IDs = new Array(); to var IDs = new Object();.

After those changes your code will run fine, but it can be simplified further. You can use shorthand notation (i.e., object literal property value shorthand) to create the object and return it immediately:

function BlockID() {
    return {

Bulk Insert to Oracle using .NET

If you are using unmanaged oracle client (Oracle.DataAccess) then the fastest way is to use OracleBulkCopy, as was pointed by Tarik.

If you are using latest managed oracle client (Oracle.ManagedDataAccess) then the fastest way is to use array binding, as was pointed by Damien. If you wish keep your application code clean from array binding specifics, you could write your own implementation of OracleBulkCopy using array binding.

Here is usage example from real project:

var bulkWriter = new OracleDbBulkWriter();
        Enumerable.Range(1, 10000).Select(v => new TestData { Id = v, StringValue=v.ToString() }).ToList());

10K records are inserted in 500ms!

Here is implementation:

public class OracleDbBulkWriter : IDbBulkWriter
    public void Write<T>(IDbConnection connection, string targetTableName, IList<T> data, IList<ColumnToPropertyMapping> mappings = null)
        if (connection == null)
            throw new ArgumentNullException(nameof(connection));
        if (string.IsNullOrEmpty(targetTableName))
            throw new ArgumentNullException(nameof(targetTableName));
        if (data == null)
            throw new ArgumentNullException(nameof(data));
        if (mappings == null)
            mappings = GetGenericMappings<T>();

        mappings = GetUniqueMappings<T>(mappings);
        Dictionary<string, Array> parameterValues = InitializeParameterValues<T>(mappings, data.Count);
        FillParameterValues(parameterValues, data);

        using (var command = CreateCommand(connection, targetTableName, mappings, parameterValues))

    private static IDbCommand CreateCommand(IDbConnection connection, string targetTableName, IList<ColumnToPropertyMapping> mappings, Dictionary<string, Array> parameterValues)
        var command = (OracleCommandWrapper)connection.CreateCommand();
        command.ArrayBindCount = parameterValues.First().Value.Length;

        foreach(var mapping in mappings)
            var parameter = command.CreateParameter();
            parameter.ParameterName = mapping.Column;
            parameter.Value = parameterValues[mapping.Property];


        command.CommandText = $@"insert into {targetTableName} ({string.Join(",", mappings.Select(m => m.Column))}) values ({string.Join(",", mappings.Select(m => $":{m.Column}")) })";
        return command;

    private IList<ColumnToPropertyMapping> GetGenericMappings<T>()
        var accessor = TypeAccessor.Create(typeof(T));

        var mappings = accessor.GetMembers()
            .Select(m => new ColumnToPropertyMapping(m.Name, m.Name))

        return mappings;

    private static IList<ColumnToPropertyMapping> GetUniqueMappings<T>(IList<ColumnToPropertyMapping> mappings)
        var accessor = TypeAccessor.Create(typeof(T));
        var members = new HashSet<string>(accessor.GetMembers().Select(m => m.Name));

        mappings = mappings
                        .Where(m => m != null && members.Contains(m.Property))
                        .GroupBy(m => m.Column)
                        .Select(g => g.First())
        return mappings;

    private static Dictionary<string, Array> InitializeParameterValues<T>(IList<ColumnToPropertyMapping> mappings, int numberOfRows)
        var values = new Dictionary<string, Array>(mappings.Count);
        var accessor = TypeAccessor.Create(typeof(T));
        var members = accessor.GetMembers().ToDictionary(m => m.Name);

        foreach(var mapping in mappings)
            var member = members[mapping.Property];

            values[mapping.Property] = Array.CreateInstance(member.Type, numberOfRows);

        return values;

    private static void FillParameterValues<T>(Dictionary<string, Array> parameterValues, IList<T> data)
        var accessor = TypeAccessor.Create(typeof(T));
        for (var rowNumber = 0; rowNumber < data.Count; rowNumber++)
            var row = data[rowNumber];
            foreach (var pair in parameterValues)
                Array parameterValue = pair.Value;
                var propertyValue = accessor[row, pair.Key];
                parameterValue.SetValue(propertyValue, rowNumber);

NOTE: this implementation uses Fastmember package for optimized access to properties(much faster than reflection)

How to get the first line of a file in a bash script?

Just echo the first list of your source file into your target file.

echo $(head -n 1 source.txt) > target.txt

How to change current Theme at runtime in Android

This is what i have created for Material Design. May it will helpful you.

Have a look for MultipleThemeMaterialDesign

Using Server.MapPath() inside a static field in ASP.NET MVC

I think you can try this for calling in from a class


*----------------Sorry I oversight, for static function already answered the question by adrift*



I got exception while using System.Web.Hosting.HostingEnvironment.MapPath("~/SignatureImages/");

Ex details : System.ArgumentException: The relative virtual path 'SignatureImages' is not allowed here. at System.Web.VirtualPath.FailIfRelativePath()

Solution (tested in static webmethod)

System.Web.HttpContext.Current.Server.MapPath("~/SignatureImages/"); Worked

Java integer to byte array

using Java NIO's ByteBuffer is very simple:

byte[] bytes = ByteBuffer.allocate(4).putInt(1695609641).array();

for (byte b : bytes) {
   System.out.format("0x%x ", b);


0x65 0x10 0xf3 0x29 

Jquery - animate height toggle

The below code worked for me in jQuery2.1.3


Need not calculate your div height,padding,margin and borders. It will take care.

How to show Snackbar when Activity starts?

You can also define a super class for all your activities and find the view once in the parent activity.

for example :

public class AppActivity extends AppCompatActivity {

    protected View content;

    protected void onCreate(@Nullable Bundle savedInstanceState) {
        content = findViewById(;

and your snacks would look like this in every activity in your app:

Snackbar.make(content, "hello every body", Snackbar.LENGTH_SHORT).show();

It is better for performance you have to find the view once for every activity.

How to import an Oracle database from dmp file and log file?

All this peace of code put into *.bat file and run all at once:

My code for creating user in oracle. crate_drop_user.sql file

drop user "USER" cascade;




alter user USER quota unlimited on "USER";


create file import.bat and put this lines in it:

SQLPLUS SYSTEM/systempassword@ORA_alias @"crate_drop_user.SQL"
IMP SYSTEM/systempassword@ORA_alias FILE=user.DMP FROMUSER=user TOUSER=user GRANTS=Y log =user.log

Be carefull if you will import from one user to another. For example if you have user named user1 and you will import to user2 you may lost all grants , so you have to recreate it.

Good luck, Ivan

get current date with 'yyyy-MM-dd' format in Angular 4

Use the following:

new Date().toLocaleDateString();

Then as per your requirement just change locale for your application:

import { registerLocaleData } from '@angular/common';
import localeFr from '@angular/common/locales/fr';

//Provide the locale in any Module or Component by the LOCALE_ID token.
providers: [
 {provide: LOCALE_ID, useValue: 'fr'}

IN vs ANY operator in PostgreSQL

(Neither IN nor ANY is an "operator". A "construct" or "syntax element".)

Logically, quoting the manual:

IN is equivalent to = ANY.

But there are two syntax variants of IN and two variants of ANY. Details:

IN taking a set is equivalent to = ANY taking a set, as demonstrated here:

But the second variant of each is not equivalent to the other. The second variant of the ANY construct takes an array (must be an actual array type), while the second variant of IN takes a comma-separated list of values. This leads to different restrictions in passing values and can also lead to different query plans in special cases:

ANY is more versatile

The ANY construct is far more versatile, as it can be combined with various operators, not just =. Example:

SELECT 'foo' LIKE ANY('{FOO,bar,%oo%}');

For a big number of values, providing a set scales better for each:


Inversion / opposite / exclusion

"Find rows where id is in the given array":

SELECT * FROM tbl WHERE id = ANY (ARRAY[1, 2]);

Inversion: "Find rows where id is not in the array":

SELECT * FROM tbl WHERE id <> ALL (ARRAY[1, 2]);
SELECT * FROM tbl WHERE id <> ALL ('{1, 2}');  -- equivalent array literal
SELECT * FROM tbl WHERE NOT (id = ANY ('{1, 2}'));

All three equivalent. The first with array constructor, the other two with array literal. The data type can be derived from context unambiguously. Else, an explicit cast may be required, like '{1,2}'::int[].

Rows with id IS NULL do not pass either of these expressions. To include NULL values additionally:

SELECT * FROM tbl WHERE (id = ANY ('{1, 2}')) IS NOT TRUE;

How to abort an interactive rebase if --abort doesn't work?

Try to follow the advice you see on the screen, and first reset your master's HEAD to the commit it expects.

git update-ref refs/heads/master b918ac16a33881ce00799bea63d9c23bf7022d67

Then, abort the rebase again.

Lost connection to MySQL server during query?

You might like to read this - - that very well explains the reasons and fixes for "lost connection during query" scenarios.

In your case, it might be because of the max allowed packet size as pointed by Augusto. Or if you've verified it isn't the case, then it might be the connection wait timeout setting due to which the client is losing connection. However, I do not think latter is true here because it's a CSV file and not containing queries.

How to save password when using Subversion from the console

None of these wonderful answers worked for me on a fresh install of Ubuntu. Instead, a clue from this answer did the trick for me.

I had to allow "simple" password store by setting this empty in ~/.subversion/config:

password-stores =

There was no existing setting, so being empty is significant.

This was in addition to:

store-passwords = yes

in ~/.subversion/servers.

.trim() in JavaScript not working in IE

It looks like that function isn't implemented in IE. If you're using jQuery, you could use $.trim() instead (

jquery $(this).id return Undefined

this : is the DOM Element $(this) : Jquery objct, which wrapped with Dom Element, you can check this answer also this vs $(this)

try like this Attr(). Get the value of an attribute for the first element in the set of matched elements.

$(document).ready(function () {
    $(".inputs").click(function () {
         alert(" or " + $(this).attr("id"));


How can I view the shared preferences file using Android Studio?

I always find these commands useful in console:

  1. Find the correct file name

    adb shell

    ls /data/data/com.your.package/shared_prefs

  2. Get the file to local directory

    adb pull /data/data/com.your.package/shared_prefs/the_file_you_want $local_dir

  3. Check it in your $local_dir.

Get a list of dates between two dates using a function

SELECT  dateadd(dd,DAYS,'2013-09-07 00:00:00') DATES
INTO        #TEMP1
(SELECT TOP 365 colorder - 1 AS DAYS from master..syscolumns 
    WHERE id = -519536829 order by colorder) a

WHERE datediff(dd,dateadd(dd,DAYS,'2013-09-07 00:00:00'),'2013-09-13 00:00:00' ) >= 0 
    AND  dateadd(dd,DAYS,'2013-09-07 00:00:00') <=  '2013-09-13 00:00:00'  

How to use variables in a command in sed?


sed "s|\$ROOT|${HOME}|"


  • Use double quotes so that the shell would expand variables.
  • Use a separator different than / since the replacement contains /
  • Escape the $ in the pattern since you don't want to expand it.

EDIT: In order to replace all occurrences of $ROOT, say

sed "s|\$ROOT|${HOME}|g"

regular expression for Indian mobile numbers


Is also a valid expression. You can precede it with either 0091,+91 or 0 and is optional.

For more details with code sample, refer to my blog.

How to properly make a http web GET request

Servers sometimes compress their responses to save on bandwidth, when this happens, you need to decompress the response before attempting to read it. Fortunately, the .NET framework can do this automatically, however, we have to turn the setting on.

Here's an example of how you could achieve that.

string html = string.Empty;
string url = @"";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.AutomaticDecompression = DecompressionMethods.GZip;

using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
using (Stream stream = response.GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
    html = reader.ReadToEnd();



public string Get(string uri)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

    using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return reader.ReadToEnd();

GET async

public async Task<string> GetAsync(string uri)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

    using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return await reader.ReadToEndAsync();

Contains the parameter method in the event you wish to use other HTTP methods such as PUT, DELETE, ETC

public string Post(string uri, string data, string contentType, string method = "POST")
    byte[] dataBytes = Encoding.UTF8.GetBytes(data);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
    request.ContentLength = dataBytes.Length;
    request.ContentType = contentType;
    request.Method = method;

    using(Stream requestBody = request.GetRequestStream())
        requestBody.Write(dataBytes, 0, dataBytes.Length);

    using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return reader.ReadToEnd();


POST async
Contains the parameter method in the event you wish to use other HTTP methods such as PUT, DELETE, ETC

public async Task<string> PostAsync(string uri, string data, string contentType, string method = "POST")
    byte[] dataBytes = Encoding.UTF8.GetBytes(data);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
    request.ContentLength = dataBytes.Length;
    request.ContentType = contentType;
    request.Method = method;

    using(Stream requestBody = request.GetRequestStream())
        await requestBody.WriteAsync(dataBytes, 0, dataBytes.Length);

    using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return await reader.ReadToEndAsync();

How to hide app title in android?

You can do it programatically:

import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

public class ActivityName extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        // remove title

Or you can do it via your AndroidManifest.xml file:

<activity android:name=".ActivityName"

Edit: I added some lines so that you can show it in fullscreen, as it seems that's what you want.

GenyMotion Unable to start the Genymotion virtual device

it worked for me when I start Gennymotion in Admin mode

How to remove all click event handlers using jQuery?

Is there a way to remove all previous click events that have been assigned to a button?


Why does this "Slow network detected..." log appear in Chrome?

I just managed to make the filter regex work: /^((?!Fallback\sfont).)*$/.

Add it to the filter field just above the console and it'll hide all messages containing Fallback font.

You can make it more specific if you want.

Entity Framework .Remove() vs. .DeleteObject()

If you really want to use Deleted, you'd have to make your foreign keys nullable, but then you'd end up with orphaned records (which is one of the main reasons you shouldn't be doing that in the first place). So just use Remove()

ObjectContext.DeleteObject(entity) marks the entity as Deleted in the context. (It's EntityState is Deleted after that.) If you call SaveChanges afterwards EF sends a SQL DELETE statement to the database. If no referential constraints in the database are violated the entity will be deleted, otherwise an exception is thrown.

EntityCollection.Remove(childEntity) marks the relationship between parent and childEntity as Deleted. If the childEntity itself is deleted from the database and what exactly happens when you call SaveChanges depends on the kind of relationship between the two:

A thing worth noting is that setting .State = EntityState.Deleted does not trigger automatically detected change. (archive)

Android Fragment onClick button Method

Your activity must have

public void insertIntoDb(View v) {

not Fragment .

If you don't want the above in activity. initialize button in fragment and set listener to the same.

    android:id="@+id/btn_conferma" // + missing


public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

   View view = inflater.inflate(R.layout.fragment_rssitem_detail,
    container, false);
   Button button = (Button) view.findViewById(;
   button.setOnClickListener(new OnClickListener()
             public void onClick(View v)
                // do something
   return view;

SQL Server: the maximum number of rows in table

It depends, but I would say it is better to keep everything in one table for that sake of simplicity.

100,000 rows a day is not really that much of an enormous amount. (Depending on your server hardware). I have personally seen MSSQL handle up to 100M rows in a single table without any problems. As long as your keep your indexes in order it should be all good. The key is to have heaps of memory so that indexes don't have to be swapped out to disk.

On the other hand, it depends on how you are using the data, if you need to make lots of query's, and its unlikely data will be needed that spans multiple days (so you won't need to join the tables) it will be faster to separate out it out into multiple tables. This is often used in applications such as industrial process control where you might be reading the value on say 50,000 instruments every 10 seconds. In this case speed is extremely important, but simplicity is not.

Copy and Paste a set range in the next empty row

The reason the code isn't working is because lastrow is measured from whatever sheet is currently active, and "A:A500" (or other number) is not a valid range reference.

Private Sub CommandButton1_Click()
    Dim lastrow As Long

    lastrow = Sheets("Summary Info").Range("A65536").End(xlUp).Row    ' or + 1
    Range("A3:E3").Copy Destination:=Sheets("Summary Info").Range("A" & lastrow)
End Sub

Python threading.timer - repeat function every 'n' seconds

This is an alternate implementation using function instead of class. Inspired by @Andrew Wilkins above.

Because wait is more accurate than sleep ( it takes function runtime into account ):

import threading

PING_ON = threading.Event()

def ping():
  while not PING_ON.wait(1):
    print("my thread %s" % str(threading.current_thread().ident))

t = threading.Thread(target=ping)


TypeError: only integer scalar arrays can be converted to a scalar index with 1D numpy indices array

A simple case that generates this error message:

In [8]: [1,2,3,4,5][np.array([1])]
TypeError                                 Traceback (most recent call last)
<ipython-input-8-55def8e1923d> in <module>()
----> 1 [1,2,3,4,5][np.array([1])]

TypeError: only integer scalar arrays can be converted to a scalar index

Some variations that work:

In [9]: [1,2,3,4,5][np.array(1)]     # this is a 0d array index
Out[9]: 2
In [10]: [1,2,3,4,5][np.array([1]).item()]    
Out[10]: 2
In [11]: np.array([1,2,3,4,5])[np.array([1])]
Out[11]: array([2])

Basic python list indexing is more restrictive than numpy's:

In [12]: [1,2,3,4,5][[1]]
TypeError: list indices must be integers or slices, not list


Looking again at

indices = np.random.choice(range(len(X_train)), replace=False, size=50000, p=train_probs)

indices is a 1d array of integers - but it certainly isn't scalar. It's an array of 50000 integers. List's cannot be indexed with multiple indices at once, regardless of whether they are in a list or array.

How to set variable from a SQL query?

You can use this, but remember that your query gives 1 result, multiple results will throw the exception.

declare @ModelID uniqueidentifer
Set @ModelID = (select Top(1) modelid from models where areaid = 'South Coast')

Another way:

Select Top(1)@ModelID = modelid from models where areaid = 'South Coast'

How do I make an asynchronous GET request in PHP?

This works fine for me, sadly you cannot retrieve the response from your request:


It works very fast, no need for raw tcp sockets :)

Detecting the onload event of a window opened with

The core problem seems to be you are opening a window to show a page whose content is already cached in the browser. Therefore no loading happens and therefore no load-event happens.

One possibility could be to use the 'pageshow' -event instead, as described in:

Insert node at a certain position in a linked list C++

Node* insert_node_at_nth_pos(Node *head, int data, int position)
    /* current node */
    Node* cur = head;

    /* initialize new node to be inserted at given position */
    Node* nth = new Node;
    nth->data = data;
    nth->next = NULL;

    if(position == 0){
        /* insert new node at head */
        head = nth;
        head->next = cur;
        return head;
        /* traverse list */
        int count = 0;            
        Node* pre = new Node;

        while(count != position){
            if(count == (position - 1)){
                pre = cur;
            cur = cur->next;            

        /* insert new node here */
        pre->next = nth;
        nth->next = cur;

        return head;

Unable to copy a file from obj\Debug to bin\Debug

Mine got solved by:

  1. Clean solution
  2. Close all processes depending on VS (Current instances).
  3. Rebuild

Initialize value of 'var' in C# to null

var variables still have a type - and the compiler error message says this type must be established during the declaration.

The specific request (assigning an initial null value) can be done, but I don't recommend it. It doesn't provide an advantage here (as the type must still be specified) and it could be viewed as making the code less readable:

var x = (String)null;

Which is still "type inferred" and equivalent to:

String x = null;

The compiler will not accept var x = null because it doesn't associate the null with any type - not even Object. Using the above approach, var x = (Object)null would "work" although it is of questionable usefulness.

Generally, when I can't use var's type inference correctly then

  1. I am at a place where it's best to declare the variable explicitly; or
  2. I should rewrite the code such that a valid value (with an established type) is assigned during the declaration.

The second approach can be done by moving code into methods or functions.

Jackson - How to process (deserialize) nested JSON?

I'm quite late to the party, but one approach is to use a static inner class to unwrap values:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

class Scratch {
    private final String aString;
    private final String bString;
    private final String cString;
    private final static String jsonString;

    static {
        jsonString = "{\n" +
                "  \"wrap\" : {\n" +
                "    \"A\": \"foo\",\n" +
                "    \"B\": \"bar\",\n" +
                "    \"C\": \"baz\"\n" +
                "  }\n" +

    Scratch(@JsonProperty("A") String aString,
            @JsonProperty("B") String bString,
            @JsonProperty("C") String cString) {
        this.aString = aString;
        this.bString = bString;
        this.cString = cString;

    public String toString() {
        return "Scratch{" +
                "aString='" + aString + '\'' +
                ", bString='" + bString + '\'' +
                ", cString='" + cString + '\'' +

    public static class JsonDeserializer {
        private final Scratch scratch;

        public JsonDeserializer(@JsonProperty("wrap") Scratch scratch) {
            this.scratch = scratch;

        public Scratch getScratch() {
            return scratch;

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        Scratch scratch = objectMapper.readValue(jsonString, Scratch.JsonDeserializer.class).getScratch();

However, it's probably easier to use objectMapper.configure(SerializationConfig.Feature.UNWRAP_ROOT_VALUE, true); in conjunction with @JsonRootName("aName"), as pointed out by pb2q

How to unset (remove) a collection element after fetching it?

Laravel Collection implements the PHP ArrayAccess interface (which is why using foreach is possible in the first place).

If you have the key already you can just use PHP unset.

I prefer this, because it clearly modifies the collection in place, and is easy to remember.

foreach ($collection as $key => $value) {

Javascript "Not a Constructor" Exception while creating objects

In my case I'd forgotten the open and close parantheses at the end of the definition of the function wrapping all of my code in the exported module. I.e. I had:

(function () {
  'use strict';

  module.exports.MyClass = class{

Instead of:

(function () {
  'use strict';

  module.exports.MyClass = class{

The compiler doesn't complain, but the require statement in the importing module doesn't set the variable it's being assigned to, so it's undefined at the point you try to construct it and it will give the TypeError: MyClass is not a constructor error.

Is there a method for String conversion to Title Case?

Apache Commons StringUtils.capitalize() or Commons Text WordUtils.capitalize()

e.g: WordUtils.capitalize("i am FINE") = "I Am FINE" from WordUtils doc

How to clear a data grid view

IF you want to clear not only Data, but also ComboBoxes, Checkboxes, try


How do I add a library path in cmake?

might fail working with link_directories, then add each static library like following:

target_link_libraries(foo /path_to_static_library/libbar.a)

Difference between "git add -A" and "git add ."

Things changed with Git 2.0 (2014-05-28):

  • -A is now the default
  • The old behavior is now available with --ignore-removal.
  • git add -u and git add -A in a subdirectory without paths on the command line operate on the entire tree.

So for Git 2 the answer is:

  • git add . and git add -A . add new/modified/deleted files in the current directory
  • git add --ignore-removal . adds new/modified files in the current directory
  • git add -u . adds modified/deleted files in the current directory
  • Without the dot, add all files in the project regardless of the current directory.

Git Symlinks in Windows

Short answer: They are now supported nicely, if you can enable developer mode.


Now in Windows 10 Creators Update, a user (with admin rights) can first enable Developer Mode, and then any user on the machine can run the mklink command without elevating a command-line console.

What drove this change? The availability and use of symlinks is a big deal to modern developers:

Many popular development tools like git and package managers like npm recognize and persist symlinks when creating repos or packages, respectively. When those repos or packages are then restored elsewhere, the symlinks are also restored, ensuring disk space (and the user’s time) isn’t wasted.

Easy to overlook with all the other announcements of the "Creator's update", but if you enable Developer Mode, you can create symlinks without elevated privileges. You might have to re-install git and make sure symlink support is enabled, as it's not by default.

Symbolic Links aren't enabled by default

What is the difference between & and && in Java?

it's as specified in the JLS (15.22.2):

When both operands of a &, ^, or | operator are of type boolean or Boolean, then the type of the bitwise operator expression is boolean. In all cases, the operands are subject to unboxing conversion (§5.1.8) as necessary.

For &, the result value is true if both operand values are true; otherwise, the result is false.

For ^, the result value is true if the operand values are different; otherwise, the result is false.

For |, the result value is false if both operand values are false; otherwise, the result is true.

The "trick" is that & is an Integer Bitwise Operator as well as an Boolean Logical Operator. So why not, seeing this as an example for operator overloading is reasonable.

Appending a list to a list of lists in R

outlist <- list(resultsa)
outlist[2] <- list(resultsb)
outlist[3] <- list(resultsc)

append's help file says it is for vectors. But it can be used here. I thought I had tried that before but there were some strange anomalies in the OP's code that may have mislead me:

outlist <- list(resultsa)
outlist <- append(outlist,list(resultsb))
outlist <- append(outlist,list(resultsc))

Same results.

Custom HTTP Authorization Header

Put it in a separate, custom header.

Overloading the standard HTTP headers is probably going to cause more confusion than it's worth, and will violate the principle of least surprise. It might also lead to interoperability problems for your API client programmers who want to use off-the-shelf tool kits that can only deal with the standard form of typical HTTP headers (such as Authorization).

How to pass values between Fragments

// In

Bundle bundle = new Bundle();
bundle.putString("key","abc"); // Put anything what you want

Fragment_2 fragment2 = new Fragment_2();

      .replace(, fragment2)

// In

Bundle bundle = this.getArguments();

if(bundle != null){
     // handle your code here.

Hope this help you.

if condition in sql server update query

The current answers are fine and should work ok, but what's wrong with the more simple, more obvious, and more maintainable:

IF @flag = 1
    UPDATE table_name SET column_A = column_A + @new_value WHERE ID = @ID;
    UPDATE table_name SET column_B = column_B + @new_value WHERE ID = @ID;

This is much easier to read albeit this is a very simple query.

Here's a working example courtesy of @snyder: SqlFiddle.

finding the type of an element using jQuery

It is worth noting that @Marius's second answer could be used as pure Javascript solution.


concatenate two database columns into one resultset column

Normal behaviour with NULL is that any operation including a NULL yields a NULL...

- 9 * NULL  = NULL  
- NULL + '' = NULL  
- etc  

To overcome this use ISNULL or COALESCE to replace any instances of NULL with something else..

SELECT (ISNULL(field1,'') + '' + ISNULL(field2,'') + '' + ISNULL(field3,'')) FROM table1

Python data structure sort list alphabetically

You can use built-in sorted function.

print sorted(['Stem', 'constitute', 'Sedge', 'Eflux', 'Whim', 'Intrigue'])

Excel 2007 - Compare 2 columns, find matching values

You could fill the C Column with variations on the following formula:


Then C would only contain values that were in A and C.

Cast to generic type in C#

I had a similar problem. I have a class;


which has a property of type T.

How do I get the property when I don't know T? I can't cast to Action<> unless I know T.


Implement a non-generic interface;

public interface IGetGenericTypeInstance
    object GenericTypeInstance();

Now I can cast the object to IGetGenericTypeInstance and GenericTypeInstance will return the property as type object.

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

AngularJS – Isolated Scopes – @ vs = vs &

Short examples with explanation are available at below link :

@ – one way binding

In directive:

scope : { nameValue : "@name" }

In view:

<my-widget name="{{nameFromParentScope}}"></my-widget>

= – two way binding

In directive:

scope : { nameValue : "=name" },
link : function(scope) { = "Changing the value here will get reflected in parent scope value";

In view:

<my-widget name="{{nameFromParentScope}}"></my-widget>

& – Function call

In directive :

scope : { nameChange : "&" }
link : function(scope) {

In view:

<my-widget nameChange="onNameChange(newName)"></my-widget>

How to stop an app on Heroku?

Go to your dashboard on heroku. Select the app. There is a dynos section. Just pull the sliders for the dynos down, (a decrease in dynos is to the left), to the number of dynos you want to be running. The slider goes to 0. Then save your changes. Boom.

According to the comment below: there is a pencil icon that needs to be clicked to accomplish this. I have not checked - but am putting it here in case it helps.

how to load CSS file into jsp

I use this version

<style><%@include file="/WEB-INF/css/style.css"%></style>

jQuery UI Tabs - How to Get Currently Selected Tab Index

Try the following:

var $tabs = $('#tabs-menu').tabs();

var selected = $tabs.tabs('option', 'selected');

var divAssocAtual = $('#tabs-menu ul li').tabs()[selected].hash;

How to Select Top 100 rows in Oracle?

First 10 customers inserted into db (table customers):

select * from customers where customer_id <=
(select  min(customer_id)+10 from customers)

Last 10 customers inserted into db (table customers):

select * from customers where customer_id >=
(select  max(customer_id)-10 from customers)

Hope this helps....

Two-dimensional array in Swift

Before using multidimensional arrays in Swift, consider their impact on performance. In my tests, the flattened array performed almost 2x better than the 2D version:

var table = [Int](repeating: 0, count: size * size)
let array = [Int](1...size)
for row in 0..<size {
    for column in 0..<size {
        let val = array[row] * array[column]
        // assign
        table[row * size + column] = val

Average execution time for filling up a 50x50 Array: 82.9ms


var table = [[Int]](repeating: [Int](repeating: 0, count: size), count: size)
let array = [Int](1...size)
for row in 0..<size {
    for column in 0..<size {
        // assign
        table[row][column] = val

Average execution time for filling up a 50x50 2D Array: 135ms

Both algorithms are O(n^2), so the difference in execution times is caused by the way we initialize the table.

Finally, the worst you can do is using append() to add new elements. That proved to be the slowest in my tests:

var table = [Int]()    
let array = [Int](1...size)
for row in 0..<size {
    for column in 0..<size {

Average execution time for filling up a 50x50 Array using append(): 2.59s


Avoid multidimensional arrays and use access by index if execution speed matters. 1D arrays are more performant, but your code might be a bit harder to understand.

You can run the performance tests yourself after downloading the demo project from my GitHub repo:

How can I mix LaTeX in with Markdown?

Sorry to rouse a really old thread, but I've been using jemdoc for a couple of years and it is really excellent.

git error: failed to push some refs to remote

I find the solution to this problem in github help.

You can see it from:Dealing with non-fast-forward errors

It says:

You can fix this by fetching and merging the changes made on the remote branch with the changes that you have made locally:

$ git fetch origin
# Fetches updates made to an online repository
$ git merge origin branch
# Merges updates made online with your local work

Or, you can simply use git pull to perform both commands at once:

$ git pull origin branch
# Grabs online updates and merges them with your local work

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

There are 2 method to overcome this

  1. Place the bootup application at start of the package structure and rest all controller inside it.

    Example :

    package; - You bootup application(i.e. Main Method, args);)

    You Rest Controller in with the same package structure Example : package;

  2. Explicitly define the Controller in the Bootup package.

Method 1 is more cleaner.

cURL POST command line on WINDOWS RESTful service

I ran into the same issue on my win7 x64 laptop and was able to get it working using the curl release that is labeled Win64 - Generic w SSL by using the very similar command line format:

C:\Projects\curl-7.23.1-win64-ssl-sspi>curl -H "Content-Type: application/json" -X POST http://localhost/someapi -d "{\"Name\":\"Test Value\"}"

Which only differs from your 2nd escape version by using double-quotes around the escaped ones and the header parameter value. Definitely prefer the linux shell syntax more.

How to create range in Swift?

I want to do this:

// out: Error

But unfortunately, I can't write a subscript of my own because the loathed one takes up the name space.

We can do this however:

print("Hello"[range: 1...3])
// out: ell 

Just add this to your project:

extension String {
    subscript(range: ClosedRange<Int>) -> String {
        get {
            let start = String.Index(utf16Offset: range.lowerBound, in: self)
            let end = String.Index(utf16Offset: range.upperBound, in: self)
            return String(self[start...end])

Android: Difference between Parcelable and Serializable?

Serializable is a standard Java interface. You simply mark a class Serializable by implementing the interface, and Java will automatically serialize it in certain situations.

Parcelable is an Android specific interface where you implement the serialization yourself. It was created to be far more efficient that Serializable, and to get around some problems with the default Java serialization scheme.

I believe that Binder and AIDL work with Parcelable objects.

However, you can use Serializable objects in Intents.

Can I change the scroll speed using css or jQuery?

I just made a pure Javascript function based on that code. Javascript only version demo:

That is the independent code from jQuery

if (window.addEventListener) {window.addEventListener('DOMMouseScroll', wheel, false); 
window.onmousewheel = document.onmousewheel = wheel;}

function wheel(event) {
    var delta = 0;
    if (event.wheelDelta) delta = (event.wheelDelta)/120 ;
    else if (event.detail) delta = -(event.detail)/3;

    if (event.preventDefault) event.preventDefault();
    event.returnValue = false;

function handle(sentido) {
    var inicial = document.body.scrollTop;
    var time = 1000;
    var distance = 200;
    delay: 0,
    duration: time,
    delta: function(p) {return p;},
    step: function(delta) {
window.scrollTo(0, inicial-distance*delta*sentido);   

function animate(opts) {
  var start = new Date();
  var id = setInterval(function() {
    var timePassed = new Date() - start;
    var progress = (timePassed / opts.duration);
    if (progress > 1) {progress = 1;}
    var delta =;
    if (progress == 1) {clearInterval(id);}}, opts.delay || 10);

How to split csv whose columns may contain ,

I had a problem with a CSV that contains fields with a quote character in them, so using the TextFieldParser, I came up with the following:

private static string[] parseCSVLine(string csvLine)
  using (TextFieldParser TFP = new TextFieldParser(new MemoryStream(Encoding.UTF8.GetBytes(csvLine))))
    TFP.HasFieldsEnclosedInQuotes = true;

      return TFP.ReadFields();
    catch (MalformedLineException)
      StringBuilder m_sbLine = new StringBuilder();

      for (int i = 0; i < TFP.ErrorLine.Length; i++)
        if (i > 0 && TFP.ErrorLine[i]== '"' &&(TFP.ErrorLine[i + 1] != ',' && TFP.ErrorLine[i - 1] != ','))

      return parseCSVLine(m_sbLine.ToString());

A StreamReader is still used to read the CSV line by line, as follows:

using(StreamReader SR = new StreamReader(FileName))
  while (SR.Peek() >-1)
    myStringArray = parseCSVLine(SR.ReadLine());

SelectedValue vs SelectedItem.Value of DropDownList

One important distinction between the two (which is visible in the Reflected code) is that SelectedValue will return an empty string if a nothing is selected, whereas SelectedItem.Value will throw a NullReference exception.

Operation must use an updatable query. (Error 3073) Microsoft Access

I had a similar problem where the following queries wouldn't work;

update tbl_Lot_Valuation_Details as LVD
set LVD.LGAName = (select LGA.LGA_NAME from tbl_Prop_LGA as LGA where LGA.LGA_CODE = LVD.LGCode)
where LVD.LGAName is null;

update tbl_LOT_VALUATION_DETAILS inner join tbl_prop_LGA on tbl_LOT_VALUATION_DETAILS.LGCode = tbl_prop_LGA.LGA_CODE 
where tbl_LOT_VALUATION_DETAILS.LGAName is null;

However using DLookup resolved the problem;

update tbl_Lot_Valuation_Details as LVD
set LVD.LGAName = dlookup("LGA_NAME", "tbl_Prop_LGA", "LGA_CODE="+LVD.LGCode)
where LVD.LGAName is null;

This solution was originally proposed at

how to delete files from amazon s3 bucket?

Use the S3FileSystem.rm function in s3fs.

You can delete a single file or several at once:

import s3fs
file_system = s3fs.S3FileSystem()

file_system.rm('s3://my-bucket/foo.txt')  # single file

files = ['s3://my-bucket/bar.txt', 's3://my-bucket/baz.txt']
file_system.rm(files)  # several files

Add object to ArrayList at specified index

You can do it like this:

list.add(1, object1)
list.add(2, object3)
list.add(2, object2)

After you add object2 to position 2, it will move object3 to position 3.

If you want object3 to be at position3 all the time I'd suggest you use a HashMap with position as key and object as a value.

Oracle - Best SELECT statement for getting the difference in minutes between two DateTime columns?

By default, oracle date subtraction returns a result in # of days.

So just multiply by 24 to get # of hours, and again by 60 for # of minutes.


  round((second_date - first_date) * (60 * 24),2) as time_in_minutes
    to_date('01/01/2008 01:30:00 PM','mm/dd/yyyy hh:mi:ss am') as first_date
   ,to_date('01/06/2008 01:35:00 PM','mm/dd/yyyy HH:MI:SS AM') as second_date
  ) test_data

What does 'useLegacyV2RuntimeActivationPolicy' do in the .NET 4 config?

Here's an explanation I wrote recently to help with the void of information on this attribute.,guid,ecc34c3c-be44-4422-86b7-900900e451f9.aspx (Internet Archive Wayback Machine link)

To quote the most relevant bits:

[Installing .NET] v4 is “non-impactful”. It should not change the behavior of existing components when installed.

The useLegacyV2RuntimeActivationPolicy attribute basically lets you say, “I have some dependencies on the legacy shim APIs. Please make them work the way they used to with respect to the chosen runtime.”

Why don’t we make this the default behavior? You might argue that this behavior is more compatible, and makes porting code from previous versions much easier. If you’ll recall, this can’t be the default behavior because it would make installation of v4 impactful, which can break existing apps installed on your machine.

The full post explains this in more detail. At RTM, the MSDN docs on this should be better. cannot identify image file - Python?

Seems like a Permissions Issue. I was facing the same error. But when I ran it from the root account, it worked. So either give the read permission to the file using chmod (in linux) or run your script after logging in as a root user.

JavaScript: What are .extend and .prototype used for?

Some extend functions in third party libraries are more complex than others. Knockout.js for instance contains a minimally simple one that doesn't have some of the checks that jQuery's does:

function extend(target, source) {
    if (source) {
        for(var prop in source) {
            if(source.hasOwnProperty(prop)) {
                target[prop] = source[prop];
    return target;

Python `if x is not None` or `if not x is None`?

Personally, I use

if not (x is None):

which is understood immediately without ambiguity by every programmer, even those not expert in the Python syntax.

JSON to pandas DataFrame

#Use the small trick to make the data json interpret-able
#Since your data is not directly interpreted by json.loads()

>>> import json
>>> f=open("sampledata.txt","r+")
>>> data =
>>> for x in data.split("\n"):
...     strlist = "["+x+"]"
...     datalist=json.loads(strlist)
...     for y in datalist:
...             print(type(y))
...             print(y)
<type 'dict'>
{u'0': [[10.8, 36.0], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'1': [[10.8, 36.1], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'2': [[10.8, 36.2], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'3': [[10.8, 36.300000000000004], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'4': [[10.8, 36.4], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'5': [[10.8, 36.5], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'6': [[10.8, 36.6], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'7': [[10.8, 36.7], {u'10': 0, u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'8': [[10.8, 36.800000000000004], {u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}
<type 'dict'>
{u'9': [[10.8, 36.9], {u'1': 0, u'0': 0, u'3': 0, u'2': 0, u'5': 0, u'4': 0, u'7': 0, u'6': 0, u'9': 0, u'8': 0}]}

Delayed rendering of React components

Depends on your use case.

If you want to do some animation of children blending in, use the react animation add-on: Otherwise, make the rendering of the children dependent on props and add the props after some delay.

I wouldn't delay in the component, because it will probably haunt you during testing. And ideally, components should be pure.

ImportError: No module named tensorflow

Try installing tensorflow in the user site - This installation only works for you.

pip install tensorflow --user

What does Maven do, in theory and in practice? When is it worth to use it?

What it does

Maven is a "build management tool", it is for defining how your .java files get compiled to .class, packaged into .jar (or .war or .ear) files, (pre/post)processed with tools, managing your CLASSPATH, and all others sorts of tasks that are required to build your project. It is similar to Apache Ant or Gradle or Makefiles in C/C++, but it attempts to be completely self-contained in it that you shouldn't need any additional tools or scripts by incorporating other common tasks like downloading & installing necessary libraries etc.

It is also designed around the "build portability" theme, so that you don't get issues as having the same code with the same buildscript working on one computer but not on another one (this is a known issue, we have VMs of Windows 98 machines since we couldn't get some of our Delphi applications compiling anywhere else). Because of this, it is also the best way to work on a project between people who use different IDEs since IDE-generated Ant scripts are hard to import into other IDEs, but all IDEs nowadays understand and support Maven (IntelliJ, Eclipse, and NetBeans). Even if you don't end up liking Maven, it ends up being the point of reference for all other modern builds tools.

Why you should use it

There are three things about Maven that are very nice.

  1. Maven will (after you declare which ones you are using) download all the libraries that you use and the libraries that they use for you automatically. This is very nice, and makes dealing with lots of libraries ridiculously easy. This lets you avoid "dependency hell". It is similar to Apache Ant's Ivy.

  2. It uses "Convention over Configuration" so that by default you don't need to define the tasks you want to do. You don't need to write a "compile", "test", "package", or "clean" step like you would have to do in Ant or a Makefile. Just put the files in the places in which Maven expects them and it should work off of the bat.

  3. Maven also has lots of nice plug-ins that you can install that will handle many routine tasks from generating Java classes from an XSD schema using JAXB to measuring test coverage with Cobertura. Just add them to your pom.xml and they will integrate with everything else you want to do.

The initial learning curve is steep, but (nearly) every professional Java developer uses Maven or wishes they did. You should use Maven on every project although don't be surprised if it takes you a while to get used to it and that sometimes you wish you could just do things manually, since learning something new sometimes hurts. However, once you truly get used to Maven you will find that build management takes almost no time at all.

How to Start

The best place to start is "Maven in 5 Minutes". It will get you start with a project ready for you to code in with all the necessary files and folders set-up (yes, I recommend using the quickstart archetype, at least at first).

After you get started you'll want a better understanding over how the tool is intended to be used. For that "Better Builds with Maven" is the most thorough place to understand the guts of how it works, however, "Maven: The Complete Reference" is more up-to-date. Read the first one for understanding, but then use the second one for reference.

Reverse of JSON.stringify?

$("#save").click(function () {
    var xx = [];
    var dd = { "firstname": "", "lastname": "", "address": "" };
    var otable1 = $("#table1").dataTable().fnGetData();

    for (var i = 0; i < otable1.length; i++) {
        dd.firstname = otable1[i][0];
        dd.lastname = otable1[i][1];
        dd.address = otable1[i][2];
        var dd = { "firstname": "", "lastname": "", "address": "" };

        url: '../Home/save',
        type: 'POST',
        data: JSON.stringify({ u: xx }),
        contentType: 'application/json;',
        dataType: 'json',
        success: function (event) {

Custom designing EditText

Use the below code in your rounded_edittext.xml :

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

    <stroke android:width="2dp"

    <corners android:radius="3dp" />

    <gradient   android:startColor="#C8C8C8"


Android; Check if file exists without creating a new one

It worked for me:

File file = new File(getApplicationContext().getFilesDir(),"whatever.txt");
       //Do something

What is the "continue" keyword and how does it work in Java?

Generally, I see continue (and break) as a warning that the code might use some refactoring, especially if the while or for loop declaration isn't immediately in sight. The same is true for return in the middle of a method, but for a slightly different reason.

As others have already said, continue moves along to the next iteration of the loop, while break moves out of the enclosing loop.

These can be maintenance timebombs because there is no immediate link between the continue/break and the loop it is continuing/breaking other than context; add an inner loop or move the "guts" of the loop into a separate method and you have a hidden effect of the continue/break failing.

IMHO, it's best to use them as a measure of last resort, and then to make sure their use is grouped together tightly at the start or end of the loop so that the next developer can see the "bounds" of the loop in one screen.

continue, break, and return (other than the One True Return at the end of your method) all fall into the general category of "hidden GOTOs". They place loop and function control in unexpected places, which then eventually causes bugs.

Can't find file executable in your configured search path for gnc gcc compiler

Just open your setting->compiler and click on the reset defaults and it will start work.

Get list of data-* attributes using javascript / jQuery

Have a look here:

If the browser also supports the HTML5 JavaScript API, you should be able to get the data with:

var attributes = element.dataset


var cat =

Oh, but I also read:

Unfortunately, the new dataset property has not yet been implemented in any browser, so in the meantime it’s best to use getAttribute and setAttribute as demonstrated earlier.

It is from May 2010.

If you use jQuery anyway, you might want to have a look at the customdata plugin. I have no experience with it though.

What is console.log?

I really feel web programming easy when i start console.log for debugging.

var i;

If i want to check value of i runtime..


you can check current value of i in firebug's console tab. It is specially used for debugging.

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

With gradle, I replaced this line at build.gradle.kts file inside dependencies block


with this


and works fine.

Reloading .env variables without restarting server (Laravel 5, shared hosting)

I know this is old, but for local dev, this is what got things back to a production .env file:

rm bootstrap/cache/config.php


php artisan config:cache
php artisan config:clear
php artisan cache:clear

Apache Spark: map vs mapPartitions?


Map transformation.

The map works on a single Row at a time.

Map returns after each input Row.

The map doesn’t hold the output result in Memory.

Map no way to figure out then to end the service.

// map example

val dfList = (1 to 100) toList

val df = dfList.toDF()

val dfInt = => x.getInt(0)+2)



MapPartition transformation.

MapPartition works on a partition at a time.

MapPartition returns after processing all the rows in the partition.

MapPartition output is retained in memory, as it can return after processing all the rows in a particular partition.

MapPartition service can be shut down before returning.

// MapPartition example

Val dfList = (1 to 100) toList

Val df = dfList.toDF()

Val df1 = df.repartition(4).rdd.mapPartition((int) => Iterator(itr.length))



For more details, please refer to the Spark map vs mapPartitions transformation article.

Hope this is helpful!

How to deal with the URISyntaxException

I had this exception in the case of a test for checking some actual accessed URLs by users.

And the URLs are sometime contains an illegal-character and hang by this error.

So I make a function to encode only the characters in the URL string like this.

String encodeIllegalChar(String uriStr,String enc)
  throws URISyntaxException,UnsupportedEncodingException {
  String _uriStr = uriStr;
  int retryCount = 17;
       new URI(_uriStr);
     }catch(URISyntaxException e){
       String reason = e.getReason();
       if(reason == null ||
          reason.contains("in path") ||
          reason.contains("in query") ||
          reason.contains("in fragment")
         throw e;
       if(0 > retryCount--){
         throw e;
       String input = e.getInput();
       int idx = e.getIndex();
       String illChar = String.valueOf(input.charAt(idx));
       _uriStr = input.replace(illChar,URLEncoder.encode(illChar,enc));
  return _uriStr;


String q =  "\\'|&`^\"<>)(}{][";
String url = "" + q + "#" + q;
String eic = encodeIllegalChar(url,'UTF-8');
System.out.println(String.format("  original:%s",url));
System.out.println(String.format("   encoded:%s",eic));
System.out.println(String.format("   uri-obj:%s",new URI(eic)));