Programs & Examples On #Chat

Generic term for "Instant Messaging System". It can also represent a discussion that occurs in an Instant Messaging System.

Android Whatsapp/Chat Examples

If you are looking to create an instant messenger for Android, this code should get you started somewhere.

Excerpt from the source :

This is a simple IM application runs on Android, application makes http request to a server, implemented in php and mysql, to authenticate, to register and to get the other friends' status and data, then it communicates with other applications in other devices by socket interface.

EDIT : Just found this! Maybe it's not related to WhatsApp. But you can use the source to understand how chat applications are programmed.

There is a website called Scringo. These awesome people provide their own SDK which you can integrate in your existing application to exploit cool features like radaring, chatting, feedback, etc. So if you are looking to integrate chat in application, you could just use their SDK. And did I say the best part? It's free!

*UPDATE : * Scringo services will be closed down on 15 February, 2015.

Best way to store chat messages in a database?

There's nothing wrong with saving the whole history in the database, they are prepared for that kind of tasks.

Actually you can find here in Stack Overflow a link to an example schema for a chat: example

If you are still worried for the size, you could apply some optimizations to group messages, like adding a buffer to your application that you only push after some time (like 1 minute or so); that way you would avoid having only 1 line messages

Change color of Label in C#

You can try this with Color.FromArgb:

Random rnd = new Random();
lbl.ForeColor = Color.FromArgb(rnd.Next(255), rnd.Next(255), rnd.Next(255));

Scroll to bottom of div?

var mydiv = $("#scroll");
mydiv.scrollTop(mydiv.prop("scrollHeight"));

Works from jQuery 1.6

https://api.jquery.com/scrollTop/

http://api.jquery.com/prop/

Automatically scroll down chat div

As I am not master in js but I myself write code which check if user is at bottom. If user is at bottom then chat page will automatically scroll with new message. and if user scroll up then page will not auto scroll to bottom..

JS code -

var checkbottom;
jQuery(function($) {
$('.chat_screen').on('scroll', function() {
    var check = $(this).scrollTop() + $(this).innerHeight() >= $(this) 
[0].scrollHeight;
    if(check) {
       checkbottom = "bottom";
    }
    else {
    checkbottom = "nobottom";
    }
})
});
window.setInterval(function(){
if (checkbottom=="bottom") {
var objDiv = document.getElementById("chat_con");
objDiv.scrollTop = objDiv.scrollHeight;
}
}, 500);

html code -

<div id="chat_con" class="chat_screen">
</div>

How to update value of a key in dictionary in c#?

Just use the indexer and update directly:

dictionary["cat"] = 3

How to check not in array element

$array1 = "Orange";
$array2 = array("Apple","Grapes","Orange","Pineapple");
if(in_array($array1,$array2)){
    echo $array1.' exists in array2';
}else{
    echo $array1.'does not exists in array2';
}

Model Binding to a List MVC 4

A clean solution could be create a generic class to handle the list, so you don't need to create a different class each time you need it.

public class ListModel<T>
{
    public List<T> Items { get; set; }

    public ListModel(List<T> list) {
        Items = list;
    }
}

and when you return the View you just need to simply do:

List<customClass> ListOfCustomClass = new List<customClass>();
//Do as needed...
return View(new ListModel<customClass>(ListOfCustomClass));

then define the list in the model:

@model ListModel<customClass>

and ready to go:

@foreach(var element in Model.Items) {
  //do as needed...
}

Use of #pragma in C

#pragma is used to do something implementation-specific in C, i.e. be pragmatic for the current context rather than ideologically dogmatic.

The one I regularly use is #pragma pack(1) where I'm trying to squeeze more out of my memory space on embedded solutions, with arrays of structures that would otherwise end up with 8 byte alignment.

Pity we don't have a #dogma yet. That would be fun ;)

mysql: SOURCE error 2?

On my windows 8.1, and mysql 5.7.9 MySQL Community Server (GPL), I had to remove the ; after the file path.

This failed: source E:/jokoni/db/Banking/createTables.sql;

This Worked: source E:/jokoni/db/Banking/createTables.sql (without termination, and forward slashes instead of windows' backslashes in path)

JavaScript implementation of Gzip

I guess a generic client-side JavaScript compression implementation would be a very expensive operation in terms of processing time as opposed to transfer time of a few more HTTP packets with uncompressed payload.

Have you done any testing that would give you an idea how much time there is to save? I mean, bandwidth savings can't be what you're after, or can it?

Using Jquery AJAX function with datatype HTML

var datos = $("#id_formulario").serialize();
$.ajax({         
    url: "url.php",      
    type: "POST",                   
    dataType: "html",                 
    data: datos,                 
    success: function (prueba) { 
        alert("funciona!");
    }//FIN SUCCES

});//FIN  AJAX

Convert sqlalchemy row object to python dict

You may access the internal __dict__ of a SQLAlchemy object, like the following::

for u in session.query(User).all():
    print u.__dict__

NPM: npm-cli.js not found when running npm

This started happening for me after I installed GoogleChrome/puppeteer, the solution was to re-install npm:

$ npm i npm@latest

or

$ npm install npm@latest

'Use of Unresolved Identifier' in Swift

Once I had this problem after renaming a file. I renamed the file from within Xcode, but afterwards Xcode couldn't find the function in the file. Even a clean rebuild didn't fix the problem, but closing and then re-opening the project got the build to work.

Simple Digit Recognition OCR in OpenCV-Python

OCR which stands for Optical Character Recognition is a computer vision technique used to identify the different types of handwritten digits that are used in common mathematics. To perform OCR in OpenCV we will use the KNN algorithm which detects the nearest k neighbors of a particular data point and then classifies that data point based on the class type detected for n neighbors.

Data Used


This data contains 5000 handwritten digits where there are 500 digits for every type of digit. Each digit is of 20×20 pixel dimensions. We will split the data such that 250 digits are for training and 250 digits are for testing for every class.

Below is the implementation.




import numpy as np
import cv2
   
      
# Read the image
image = cv2.imread('digits.png')
  
# gray scale conversion
gray_img = cv2.cvtColor(image,
                        cv2.COLOR_BGR2GRAY)
  
# We will divide the image
# into 5000 small dimensions 
# of size 20x20
divisions = list(np.hsplit(i,100) for i in np.vsplit(gray_img,50))
  
# Convert into Numpy array
# of size (50,100,20,20)
NP_array = np.array(divisions)
   
# Preparing train_data
# and test_data.
# Size will be (2500,20x20)
train_data = NP_array[:,:50].reshape(-1,400).astype(np.float32)
  
# Size will be (2500,20x20)
test_data = NP_array[:,50:100].reshape(-1,400).astype(np.float32)
  
# Create 10 different labels 
# for each type of digit
k = np.arange(10)
train_labels = np.repeat(k,250)[:,np.newaxis]
test_labels = np.repeat(k,250)[:,np.newaxis]
   
# Initiate kNN classifier
knn = cv2.ml.KNearest_create()
  
# perform training of data
knn.train(train_data,
          cv2.ml.ROW_SAMPLE, 
          train_labels)
   
# obtain the output from the
# classifier by specifying the
# number of neighbors.
ret, output ,neighbours,
distance = knn.findNearest(test_data, k = 3)
   
# Check the performance and
# accuracy of the classifier.
# Compare the output with test_labels
# to find out how many are wrong.
matched = output==test_labels
correct_OP = np.count_nonzero(matched)
   
#Calculate the accuracy.
accuracy = (correct_OP*100.0)/(output.size)
   
# Display accuracy.
print(accuracy)


Output

91.64


Well, I decided to workout myself on my question to solve the above problem. What I wanted is to implement a simple OCR using KNearest or SVM features in OpenCV. And below is what I did and how. (it is just for learning how to use KNearest for simple OCR purposes).

1) My first question was about letter_recognition.data file that comes with OpenCV samples. I wanted to know what is inside that file.

It contains a letter, along with 16 features of that letter.

And this SOF helped me to find it. These 16 features are explained in the paper Letter Recognition Using Holland-Style Adaptive Classifiers. (Although I didn't understand some of the features at the end)

2) Since I knew, without understanding all those features, it is difficult to do that method. I tried some other papers, but all were a little difficult for a beginner.

So I just decided to take all the pixel values as my features. (I was not worried about accuracy or performance, I just wanted it to work, at least with the least accuracy)

I took the below image for my training data:

enter image description here

(I know the amount of training data is less. But, since all letters are of the same font and size, I decided to try on this).

To prepare the data for training, I made a small code in OpenCV. It does the following things:

  1. It loads the image.
  2. Selects the digits (obviously by contour finding and applying constraints on area and height of letters to avoid false detections).
  3. Draws the bounding rectangle around one letter and wait for key press manually. This time we press the digit key ourselves corresponding to the letter in the box.
  4. Once the corresponding digit key is pressed, it resizes this box to 10x10 and saves all 100 pixel values in an array (here, samples) and corresponding manually entered digit in another array(here, responses).
  5. Then save both the arrays in separate .txt files.

At the end of the manual classification of digits, all the digits in the training data (train.png) are labeled manually by ourselves, image will look like below:

enter image description here

Below is the code I used for the above purpose (of course, not so clean):

import sys

import numpy as np
import cv2

im = cv2.imread('pitrain.png')
im3 = im.copy()

gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray,(5,5),0)
thresh = cv2.adaptiveThreshold(blur,255,1,1,11,2)

#################      Now finding Contours         ###################

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

samples =  np.empty((0,100))
responses = []
keys = [i for i in range(48,58)]

for cnt in contours:
    if cv2.contourArea(cnt)>50:
        [x,y,w,h] = cv2.boundingRect(cnt)
        
        if  h>28:
            cv2.rectangle(im,(x,y),(x+w,y+h),(0,0,255),2)
            roi = thresh[y:y+h,x:x+w]
            roismall = cv2.resize(roi,(10,10))
            cv2.imshow('norm',im)
            key = cv2.waitKey(0)

            if key == 27:  # (escape to quit)
                sys.exit()
            elif key in keys:
                responses.append(int(chr(key)))
                sample = roismall.reshape((1,100))
                samples = np.append(samples,sample,0)

responses = np.array(responses,np.float32)
responses = responses.reshape((responses.size,1))
print "training complete"

np.savetxt('generalsamples.data',samples)
np.savetxt('generalresponses.data',responses)

Now we enter in to training and testing part.

For the testing part, I used the below image, which has the same type of letters I used for the training phase.

enter image description here

For training we do as follows:

  1. Load the .txt files we already saved earlier
  2. create an instance of the classifier we are using (it is KNearest in this case)
  3. Then we use KNearest.train function to train the data

For testing purposes, we do as follows:

  1. We load the image used for testing
  2. process the image as earlier and extract each digit using contour methods
  3. Draw a bounding box for it, then resize it to 10x10, and store its pixel values in an array as done earlier.
  4. Then we use KNearest.find_nearest() function to find the nearest item to the one we gave. ( If lucky, it recognizes the correct digit.)

I included last two steps (training and testing) in single code below:

import cv2
import numpy as np

#######   training part    ############### 
samples = np.loadtxt('generalsamples.data',np.float32)
responses = np.loadtxt('generalresponses.data',np.float32)
responses = responses.reshape((responses.size,1))

model = cv2.KNearest()
model.train(samples,responses)

############################# testing part  #########################

im = cv2.imread('pi.png')
out = np.zeros(im.shape,np.uint8)
gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
thresh = cv2.adaptiveThreshold(gray,255,1,1,11,2)

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

for cnt in contours:
    if cv2.contourArea(cnt)>50:
        [x,y,w,h] = cv2.boundingRect(cnt)
        if  h>28:
            cv2.rectangle(im,(x,y),(x+w,y+h),(0,255,0),2)
            roi = thresh[y:y+h,x:x+w]
            roismall = cv2.resize(roi,(10,10))
            roismall = roismall.reshape((1,100))
            roismall = np.float32(roismall)
            retval, results, neigh_resp, dists = model.find_nearest(roismall, k = 1)
            string = str(int((results[0][0])))
            cv2.putText(out,string,(x,y+h),0,1,(0,255,0))

cv2.imshow('im',im)
cv2.imshow('out',out)
cv2.waitKey(0)

And it worked, below is the result I got:

enter image description here


Here it worked with 100% accuracy. I assume this is because all the digits are of the same kind and the same size.

But anyway, this is a good start to go for beginners (I hope so).

Loop through checkboxes and count each one checked or unchecked

You can loop through all of the checkboxes by writing $(':checkbox').each(...).

If I understand your question correctly, you're looking for the following code:

var str = "";

$(':checkbox').each(function() {
    str += this.checked ? "1," : "0,";
});

str = str.substr(0, str.length - 1);    //Remove the trailing comma

This code will loop through all of the checkboxes and add either 1, or 0, to a string.

LINK : fatal error LNK1104: cannot open file 'D:\...\MyProj.exe'

I have just run into the same issue with VS2013, creating device drivers in C++ , and none of the above seemed to fix the issue. However, I have just discovered that in my case the issue appears to have been VMWare-related.

I was running a VMWare workstation client with a shared folder defined on the VM on my entire C: drive. When I disabled the shared folders on the VM Settings, VS2013 was able to happily build my .exe files.

My new process is:

1) Disable the shared folder on the vm (VM Settings | Options | Shared Folders - and uncheck the checkbox) 2) Run the build on the host PC 3) RE-enable the shared folder (and proceed from there)

Hopefully this might help someone else.

(BTW, the errors you receive are that the .exe (or other files) are locked or require Administrator permission, but that is a red herring - It seems to me that the VMWare share is causing those files to appear as locked.)

How do I format a number in Java?

public static void formatDouble(double myDouble){
 NumberFormat numberFormatter = new DecimalFormat("##.000");
 String result = numberFormatter.format(myDouble);
 System.out.println(result);
}

For instance, if the double value passed into the formatDouble() method is 345.9372, the following will be the result: 345.937 Similarly, if the value .7697 is passed to the method, the following will be the result: .770

Can I embed a custom font in an iPhone application?

Here's the step by step instructions how to do it. No need extra library or any special coding.

http://shang-liang.com/blog/custom-fonts-in-ios4/

Most of the time the issue is with the font not the method. The best way to do it is to use a font that for sure will work, like verdana or geogia. Then change to the intended font. If it does not work, maybe the font name is not right, or the font is not a well formated font.

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

I finally was able to figure out a simple solution without the @Query annotation.

List<People> findDistinctByNameNotIn(List<String> names);

Of course, I got the people object instead of only Strings. I can then do the change in java.

Way to create multiline comments in Bash?

Here's how I do multiline comments in bash.

This mechanism has two advantages that I appreciate. One is that comments can be nested. The other is that blocks can be enabled by simply commenting out the initiating line.

#!/bin/bash
# : <<'####.block.A'
echo "foo {" 1>&2
fn data1
echo "foo }" 1>&2
: <<'####.block.B'
fn data2 || exit
exit 1
####.block.B
echo "can't happen" 1>&2
####.block.A

In the example above the "B" block is commented out, but the parts of the "A" block that are not the "B" block are not commented out.

Running that example will produce this output:

foo {
./example: line 5: fn: command not found
foo }
can't happen

Rails - Could not find a JavaScript runtime?

Note from Michael 12/28/2011 - I have changed my accept from this (rubytheracer) to above (nodejs) as therubyracer has code size issues. Heroku now strongly discourage it. It will 'work' but may have size/performance issues.

If you add a runtime, such as therubyracer to your Gemfile and run bundle then try and start the server it should work.

gem 'therubyracer'

A javascript runtime is required for compiling coffeescript and also for uglifier.

Update, 12/12/2011: Some folks found issues with rubytheracer (I think it was mostly code size). They found execjs (or nodejs) worked just as well (if not better) and were much smaller.

n.b. Coffeescript became a standard for 3.1+

How to multiply individual elements of a list with a number?

In NumPy it is quite simple

import numpy as np
P=2.45
S=[22, 33, 45.6, 21.6, 51.8]
SP = P*np.array(S)

I recommend taking a look at the NumPy tutorial for an explanation of the full capabilities of NumPy's arrays:

https://scipy.github.io/old-wiki/pages/Tentative_NumPy_Tutorial

Capitalize the first letter of string in AngularJs

a nicer way

app.filter('capitalize', function() {
  return function(token) {
      return token.charAt(0).toUpperCase() + token.slice(1);
   }
});

jQuery xml error ' No 'Access-Control-Allow-Origin' header is present on the requested resource.'

There's a kind of hack-tastic way to do it if you have php enabled on your server. Change this line:

url:   'http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml',

to this line:

url: '/path/to/phpscript.php',

and then in the php script (if you have permission to use the file_get_contents() function):

<?php

header('Content-type: application/xml');
echo file_get_contents("http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml");

?>

Php doesn't seem to mind if that url is from a different origin. Like I said, this is a hacky answer, and I'm sure there's something wrong with it, but it works for me.

Edit: If you want to cache the result in php, here's the php file you would use:

<?php

$cacheName = 'somefile.xml.cache';
// generate the cache version if it doesn't exist or it's too old!
$ageInSeconds = 3600; // one hour
if(!file_exists($cacheName) || filemtime($cacheName) > time() + $ageInSeconds) {
  $contents = file_get_contents('http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml');
  file_put_contents($cacheName, $contents);
}

$xml = simplexml_load_file($cacheName);

header('Content-type: application/xml');
echo $xml;

?>

Caching code take from here.

clear javascript console in Google Chrome

Based on Cobbal's answer, here's what I did:

In my JavaScript I put the following:

setInterval(function() {
  if(window.clear) {
    window.clear();
    console.log("this is highly repeated code");
  }
}, 10);

The conditional code won't run until you ASSIGN window.clear (meaning your log is empty until you do so). IN THE DEBUG CONSOLE TYPE:

window.clear = clear;

Violà - a log that clears itself.

Mac OS 10.6.8 - Chrome 15.0.874.106

How to hide a column (GridView) but still access its value?

You can do it programmatically:

grid0.Columns[0].Visible = true;
grid0.DataSource = dt;
grid0.DataBind();
grid0.Columns[0].Visible = false;

In this way you set the column to visible before databinding, so the column is generated. The you set the column to not visible, so it is not displayed.

How to read a file in reverse order?

I had to do this some time ago and used the below code. It pipes to the shell. I am afraid i do not have the complete script anymore. If you are on a unixish operating system, you can use "tac", however on e.g. Mac OSX tac command does not work, use tail -r. The below code snippet tests for which platform you're on, and adjusts the command accordingly

# We need a command to reverse the line order of the file. On Linux this
# is 'tac', on OSX it is 'tail -r'
# 'tac' is not supported on osx, 'tail -r' is not supported on linux.

if sys.platform == "darwin":
    command += "|tail -r"
elif sys.platform == "linux2":
    command += "|tac"
else:
    raise EnvironmentError('Platform %s not supported' % sys.platform)

Nodejs send file in response

Here's an example program that will send myfile.mp3 by streaming it from disk (that is, it doesn't read the whole file into memory before sending the file). The server listens on port 2000.

[Update] As mentioned by @Aftershock in the comments, util.pump is gone and was replaced with a method on the Stream prototype called pipe; the code below reflects this.

var http = require('http'),
    fileSystem = require('fs'),
    path = require('path');

http.createServer(function(request, response) {
    var filePath = path.join(__dirname, 'myfile.mp3');
    var stat = fileSystem.statSync(filePath);

    response.writeHead(200, {
        'Content-Type': 'audio/mpeg',
        'Content-Length': stat.size
    });

    var readStream = fileSystem.createReadStream(filePath);
    // We replaced all the event handlers with a simple call to readStream.pipe()
    readStream.pipe(response);
})
.listen(2000);

Taken from http://elegantcode.com/2011/04/06/taking-baby-steps-with-node-js-pumping-data-between-streams/

How can I override the OnBeforeUnload dialog and replace it with my own?

You can't modify the default dialogue for onbeforeunload, so your best bet may be to work with it.

window.onbeforeunload = function() {
    return 'You have unsaved changes!';
}

Here's a reference to this from Microsoft:

When a string is assigned to the returnValue property of window.event, a dialog box appears that gives users the option to stay on the current page and retain the string that was assigned to it. The default statement that appears in the dialog box, "Are you sure you want to navigate away from this page? ... Press OK to continue, or Cancel to stay on the current page.", cannot be removed or altered.

The problem seems to be:

  1. When onbeforeunload is called, it will take the return value of the handler as window.event.returnValue.
  2. It will then parse the return value as a string (unless it is null).
  3. Since false is parsed as a string, the dialogue box will fire, which will then pass an appropriate true/false.

The result is, there doesn't seem to be a way of assigning false to onbeforeunload to prevent it from the default dialogue.

Additional notes on jQuery:

  • Setting the event in jQuery may be problematic, as that allows other onbeforeunload events to occur as well. If you wish only for your unload event to occur I'd stick to plain ol' JavaScript for it.
  • jQuery doesn't have a shortcut for onbeforeunload so you'd have to use the generic bind syntax.

    $(window).bind('beforeunload', function() {} );
    

Edit 09/04/2018: custom messages in onbeforeunload dialogs are deprecated since chrome-51 (cf: release note)

How do I stop a web page from scrolling to the top when a link is clicked that triggers JavaScript?

When calling the function, follow it by return false example:

<input  type="submit" value="Add" onclick="addNewPayment();return false;">

Unicode via CSS :before

At first link fontwaesome CSS file in your HTML file then create an after or before pseudo class like "font-family: "FontAwesome"; content: "\f101";" then save. I hope this work good.

How can I remove item from querystring in asp.net using c#?

Try this ...

PropertyInfo isreadonly   =typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);    

isreadonly.SetValue(this.Request.QueryString, false, null);
this.Request.QueryString.Remove("foo");

Create an empty object in JavaScript with {} or new Object()?

I believe {} was recommended in one of the Javascript vids on here as a good coding convention. new is necessary for pseudoclassical inheritance. the var obj = {}; way helps to remind you that this is not a classical object oriented language but a prototypal one. Thus the only time you would really need new is when you are using constructors functions. For example:

var Mammal = function (name) {
  this.name = name;
};

Mammal.prototype.get_name = function () {
  return this.name;
}

Mammal.prototype.says = function() {
  return this.saying || '';
}

Then it is used like so:

var aMammal = new Mammal('Me warm-blooded');
var name = aMammal.get_name();

Another advantage to using {} as oppose to new Object is you can use it to do JSON-style object literals.

How do I load a file into the python console?

You can just use an import statement:

from file import *

So, for example, if you had a file named my_script.py you'd load it like so:

from my_script import *

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed

MySQL implicitly closed the database connection because the connection has been inactive for too long (34,247,052 milliseconds ˜ 9.5 hours). If your program then fetches a bad connection from the connection-pool that causes the MySQLNonTransientConnectionException: No operations allowed after connection closed.

MySQL suggests:

You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property autoReconnect=true to avoid this problem.

Vbscript list all PDF files in folder and subfolders

(For those who stumble upon this from your search engine of choice)

This just recursively traces down the folder, so you don't need to duplicate your code twice. Also the OPs logic is needlessly complex.

Wscript.Echo "begin."
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objSuperFolder = objFSO.GetFolder(WScript.Arguments(0))
Call ShowSubfolders (objSuperFolder)

Wscript.Echo "end."

WScript.Quit 0

Sub ShowSubFolders(fFolder)
    Set objFolder = objFSO.GetFolder(fFolder.Path)
    Set colFiles = objFolder.Files
    For Each objFile in colFiles
        If UCase(objFSO.GetExtensionName(objFile.name)) = "PDF" Then
            Wscript.Echo objFile.Name
        End If
    Next

    For Each Subfolder in fFolder.SubFolders
        ShowSubFolders(Subfolder)
    Next
End Sub

Count number of rows per group and add result to original data frame

One simple line in base R:

df$count = table(interaction(df[, (c("name", "type"))]))[interaction(df[, (c("name", "type"))])]

Same in two lines, for clarity/efficiency:

fact = interaction(df[, (c("name", "type"))])
df$count = table(fact)[fact]

DLL References in Visual C++

The additional include directories are relative to the project dir. This is normally the dir where your project file, *.vcproj, is located. I guess that in your case you have to add just "include" to your include and library directories.

If you want to be sure what your project dir is, you can check the value of the $(ProjectDir) macro. To do that go to "C/C++ -> Additional Include Directories", press the "..." button and in the pop-up dialog press "Macros>>".

How to join two tables by multiple columns in SQL?

Yes: You can use Inner Join to join on multiple columns.

SELECT E.CaseNum, E.FileNum, E.ActivityNum, E.Grade, V.Score from Evaluation E
INNER JOIN Value V
ON E.CaseNum = V.CaseNum AND
    E.FileNum = V.FileNum AND 
    E.ActivityNum = V.ActivityNum

Create table

CREATE TABLE MyNewTab(CaseNum int, FileNum int,
    ActivityNum int, Grade int, Score varchar(100))

Insert values

INSERT INTO MyNewTab Values(CaseNum, FileNum, ActivityNum, Grade, Score)
SELECT E.CaseNum, E.FileNum, E.ActivityNum, E.Grade, V.Score from Evaluation E
INNER JOIN Value V
ON E.CaseNum = V.CaseNum AND
    E.FileNum = V.FileNum AND 
    E.ActivityNum = V.ActivityNum

Android: How to turn screen on and off programmatically?

The best way to do it ( using rooted devices) :

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    .
    .
    .

    int flags = WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON;
    getWindow().addFlags(flags); // this is how your app will wake up the screen
    //you will call this activity later

   .
   .
   .
}

Now we have this two functions:

private void turnOffScreen(){

  try{
     Class c = Class.forName("android.os.PowerManager");
     PowerManager  mPowerManager = (PowerManager) this.getSystemService(Context.POWER_SERVICE);
     for(Method m : c.getDeclaredMethods()){
        if(m.getName().equals("goToSleep")){
          m.setAccessible(true);
          if(m.getParameterTypes().length == 1){
            m.invoke(mPowerManager,SystemClock.uptimeMillis()-2);
          }
        }
     } 
  } catch (Exception e){
  }
}

And this:

public void turnOnScreen(){
  Intent i = new Intent(this,YOURACTIVITYWITHFLAGS.class);
  startActivity(i);
}

Sorry for my bad english.

What does it mean when MySQL is in the state "Sending data"?

In this state:

The thread is reading and processing rows for a SELECT statement, and sending data to the client.

Because operations occurring during this this state tend to perform large amounts of disk access (reads).

That's why it takes more time to complete and so is the longest-running state over the lifetime of a given query.

What are the recommendations for html <base> tag?

Working with AngularJS the BASE tag broke $cookieStore silently and it took me a while to figure out why my app couldn't write cookies anymore. Be warned...

How to create duplicate table with new name in SQL Server 2008

To create a new table from an existing table: (copying all rows from Old_Table into de New_Table):

SELECT * INTO New_table FROM  Old_Table

To copy the data from one table to another (when you have already created them):

Insert into Table_Name2 select top 1 * from Table_Name1

Remember to remove the top 1 argument and apply a relevant where clause if needed on the Select

increase font size of hyperlink text html

increase the padding size of font and then try to increase font size:-

style="padding-bottom:40px; font-size: 50px;"

Script to get the HTTP status code of a list of urls?

I found a tool "webchk” written in Python. Returns a status code for a list of urls. https://pypi.org/project/webchk/

Output looks like this:

? webchk -i ./dxieu.txt | grep '200'
http://salesforce-case-status.dxi.eu/login ... 200 OK (0.108)
https://support.dxi.eu/hc/en-gb ... 200 OK (0.389)
https://support.dxi.eu/hc/en-gb ... 200 OK (0.401)

Hope that helps!

"Could not find a part of the path" error message

I had the same error, although in my case the problem was with the formatting of the DESTINATION path. The comments above are correct with respect to debugging the path string formatting, but there seems to be a bug in the File.Copy exception reporting where it still throws back the SOURCE path instead of the DESTINATION path. So don't forget to look here as well.

-TC

How to find my Subversion server version number?

There really isn't an easy way to find out what version of Subversion your server is running -- except to get onto the server and see for yourself.

However, this may not be as big a problem as you may think. Subversion clients is were much of the grunt work is handled, and most versions of the Subversion clients can work with almost any version of the server.

The last release where the server version really made a difference to the client was the change from release 1.4 to release 1.5 when merge tracking was added. Merge tracking had been greatly improved in version 1.6, but that doesn't really affect the interactions between the client and server.

Let's take the latest changes in Subversion 1.8:

  • svn move is now a first class operation: Subversion finally understands the svn move is not a svn copy and svn delete. However, this is something that the client handles and doesn't really affect the server version.
  • svn merge --reintegrate deprecated: Again, as long as the server is at version 1.5 or greater this isn't an issue.
  • Property Inheritance: This is another 1.8 release update, but this will work with any Subversion server -- although Subversion servers running 1.8 will deliver better performance on inheritable properties.
  • Two new inheritable properties - svn:global-ignores and svn:auto-props: Alas! What we really wanted. A way to setup these two properties without depending upon the Subversion configuration file itself. However, this is a client-only issue, so it again doesn't matter what version of the server you're using.
  • gnu-agent memory caching: Another client-only feature.
  • fsfs performance enhancements and authz in-repository authentication. Nice features, but these work no matter what version of the client you're using.

Of all the features, only one depends upon the version of the server being 1.5 or greater (and 1.4 has been obsolete for quite a while. The newer features of 1.8 will improve performance of your working copy, but the server being at revision 1.8 isn't necessary. You're much more affected by your client version than your server version.

I know this isn't the answer you wanted (no official way to see the server version), but fortunately the server version doesn't really affect you that much.

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

.pyc contain the compiled bytecode of Python source files. The Python interpreter loads .pyc files before .py files, so if they're present, it can save some time by not having to re-compile the Python source code. You can get rid of them if you want, but they don't cause problems, they're not big, and they may save some time when running programs.

How to check if an object is defined?

If a class type is not defined, you'll get a compiler error if you try to use the class, so in that sense you should have to check.

If you have an instance, and you want to ensure it's not null, simply check for null:

if (value != null)
{
    // it's not null. 
}

How can I submit form on button click when using preventDefault()?

Change the submit button to a normal button and handle submitting in its onClick event.

As far as I know, there is no way to tell if the form was submitted by Enter Key or the submit button.

jQuery - add additional parameters on submit (NOT ajax)

This one did it for me:

var input = $("<input>")
               .attr("type", "hidden")
               .attr("name", "mydata").val("bla");
$('#form1').append(input);

is based on the Daff's answer, but added the NAME attribute to let it show in the form collection and changed VALUE to VAL Also checked the ID of the FORM (form1 in my case)

used the Firefox firebug to check whether the element was inserted.

Hidden elements do get posted back in the form collection, only read-only fields are discarded.

Michel

How do I make a Mac Terminal pop-up/alert? Applescript?

Use this command to trigger the notification center notification from the terminal.

osascript -e 'display notification "Lorem ipsum dolor sit amet" with title "Title"'

How do I set the eclipse.ini -vm option?

-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20140415-2008.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.200.v20140603-1326
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
512M
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
512m
--launcher.defaultAction
openFile
--launcher.appendVmargs
-vmargs
-Dosgi.requiredJavaVersion=1.6
-Xms2000m
-Xmx3512m

POST request via RestTemplate in JSON

This code is working for me;

RestTemplate restTemplate = new RestTemplate();
Payment payment = new Payment("Aa4bhs");
MultiValueMap<String, Object> map = new LinkedMultiValueMap<String, Object>();
map.add("payment", payment);
HttpEntity<MultiValueMap<String, Object>> httpEntity = new HttpEntity<MultiValueMap<String, Object>>(map, headerObject);

Payment res = restTemplate.postForObject(url, httpEntity, Payment.class);

Create a circular button in BS3

To add a rounded border in any button the best way is to add the border-radius property. I belive this class is better because you can add-it at any button size. If you set the height and widht you will need to create a "rouding" class to each button size.

_x000D_
_x000D_
.btn-circle {_x000D_
  border-radius: 50%;_x000D_
}
_x000D_
<button class='btn-circle'>Click Me!</button>_x000D_
<button class='btn-circle'>?</button>
_x000D_
_x000D_
_x000D_

Is there a simple way to use button to navigate page as a link does in angularjs

For me, best solution is to use Angular router native directives with ui-sref like:

<button ui-sref="state.name">Go!!</button>

To understand that directive and get more options visit ui-router docs at:

https://ui-router.github.io/docs/0.3.1/#/api/ui.router.state.directive:ui-sref

: )

Why is git push gerrit HEAD:refs/for/master used instead of git push origin master

In order to avoid having to fully specify the git push command you could alternatively modify your git config file:

[remote "gerrit"]
    url = https://your.gerrit.repo:44444/repo
    fetch = +refs/heads/master:refs/remotes/origin/master
    push = refs/heads/master:refs/for/master

Now you can simply:

git fetch gerrit
git push gerrit

This is according to Gerrit

Unable to run Java GUI programs with Ubuntu

Ubuntu has the option to install a headless Java -- this means without graphics libraries. This wasn't always the case, but I encountered this while trying to run a Java text editor on 10.10 the other day. Run the following command to install a JDK that has these libraries:

sudo apt-get install openjdk-6-jdk

EDIT: Actually, looking at my config, you might need the JRE. If that's the case, run:

sudo apt-get install openjdk-6-jre

How can I get the SQL of a PreparedStatement?

It's nowhere definied in the JDBC API contract, but if you're lucky, the JDBC driver in question may return the complete SQL by just calling PreparedStatement#toString(). I.e.

System.out.println(preparedStatement);

At least MySQL 5.x and PostgreSQL 8.x JDBC drivers support it. However, most other JDBC drivers doesn't support it. If you have such one, then your best bet is using Log4jdbc or P6Spy.

Alternatively, you can also write a generic function which takes a Connection, a SQL string and the statement values and returns a PreparedStatement after logging the SQL string and the values. Kickoff example:

public static PreparedStatement prepareStatement(Connection connection, String sql, Object... values) throws SQLException {
    PreparedStatement preparedStatement = connection.prepareStatement(sql);
    for (int i = 0; i < values.length; i++) {
        preparedStatement.setObject(i + 1, values[i]);
    }
    logger.debug(sql + " " + Arrays.asList(values));
    return preparedStatement;
}

and use it as

try {
    connection = database.getConnection();
    preparedStatement = prepareStatement(connection, SQL, values);
    resultSet = preparedStatement.executeQuery();
    // ...

Another alternative is to implement a custom PreparedStatement which wraps (decorates) the real PreparedStatement on construction and overrides all the methods so that it calls the methods of the real PreparedStatement and collects the values in all the setXXX() methods and lazily constructs the "actual" SQL string whenever one of the executeXXX() methods is called (quite a work, but most IDE's provides autogenerators for decorator methods, Eclipse does). Finally just use it instead. That's also basically what P6Spy and consorts already do under the hoods.

Why do I keep getting 'SVN: Working Copy XXXX locked; try performing 'cleanup'?

Solution: Step1: Have to remove “lock” file which present under “.svn” hidden file. Step2: In case if there is no “lock” file then you would see “we.db” you have to open this database and need to delete content alone from the following tables – lock – wc_lock Step3: Clean your project Step4: Try to commit now. Step5: Done.

SQlite - Android - Foreign key syntax

You have to define your TASK_CAT column first and then set foreign key on it.

private static final String TASK_TABLE_CREATE = "create table "
        + TASK_TABLE + " (" 
        + TASK_ID + " integer primary key autoincrement, " 
        + TASK_TITLE + " text not null, " 
        + TASK_NOTES + " text not null, "
        + TASK_DATE_TIME + " text not null,"
        + TASK_CAT + " integer,"
        + " FOREIGN KEY ("+TASK_CAT+") REFERENCES "+CAT_TABLE+"("+CAT_ID+"));";

More information you can find on sqlite foreign keys doc.

Is quitting an application frowned upon?

Almost 99% of the time there is no need for an Android application to take over its own life cycle. Most of the time it comes down to better planning or smarter design of the application. For example, rather build an internal service (not exported) to handle downloads, etc., or design actions and tasks around user workflow.

But that being said, where there is a will there is a way. Android provides - through the android.os.Process class, a much better API than Java to control the underlying process. And unlike Java it does not treat the developer like a moron by hiding it all behind a simple java.lang.System.exit() call.

So how do you ask your application to commit suicide in Android? Well, the trick is simple:

Create your own Android application class by inheriting from the standard android.app.Application class (remember to declare it in the AndroidManifest.xml file).

Override the onCreate() method, and store the process ID which started your application:

this.pid = android.os.Process.myPid(); // Save for later use.

Now to kill your application, provide a kill() method:

android.os.Process.sendSignal(pid, android.os.Process.SIGNAL_KILL);

Now whenever you need your app to commit suicide just type cast the application context, and call your kill method!

((MySuicidalApp) context.getApplicationContext()).kill()

Just remember that due to the process management policies in Android, specifically related to services, Android may just opt to restart your service (see You should not use task killers on Android).

Inserting multiple rows in mysql

If you have your data in a text-file, you can use LOAD DATA INFILE.

When loading a table from a text file, use LOAD DATA INFILE. This is usually 20 times faster than using INSERT statements.

Optimizing INSERT Statements

You can find more tips on how to speed up your insert statements on the link above.

error C4996: 'scanf': This function or variable may be unsafe in c programming

You can add "_CRT_SECURE_NO_WARNINGS" in Preprocessor Definitions.

Right-click your project->Properties->Configuration Properties->C/C++ ->Preprocessor->Preprocessor Definitions.

enter image description here

Is a URL allowed to contain a space?

Yes, the space is usually encoded to "%20" though. Any parameters that pass to a URL should be encoded, simply for safety reasons.

How to define several include path in Makefile

Make's substitutions feature is nice and helped me to write

%.i: src/%.c $(INCLUDE)
        gcc -E $(CPPFLAGS) $(INCLUDE:%=-I %) $< > $@

You might find this useful, because it asks make to check for changes in include folders too

How might I find the largest number contained in a JavaScript array?

Run this:

Array.prototype.max = function(){
    return Math.max.apply( Math, this );
};

And now try [3,10,2].max() returns 10

How to only find files in a given directory, and ignore subdirectories using bash

I got here with a bit more general problem - I wanted to find files in directories matching pattern but not in their subdirectories.

My solution (assuming we're looking for all cpp files living directly in arch directories):

find . -path "*/arch/*/*" -prune -o -path "*/arch/*.cpp" -print

I couldn't use maxdepth since it limited search in the first place, and didn't know names of subdirectories that I wanted to exclude.

How to Set AllowOverride all

In case you are on Ubuntu, edit the file /etc/apache2/apache2.conf (here we have an example of /var/www):

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride None
        Require all granted
</Directory>

and change it to;

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
</Directory>

then,

sudo service apache2 restart

You may need to also do sudo a2enmod rewrite to enable module rewrite.

How to wait until an element exists?

This is a simple solution for those who are used to promises and don't want to use any third party libs or timers.

I have been using it in my projects for a while

function waitForElm(selector) {
    return new Promise(resolve => {
        if (document.querySelector(selector)) {
            return resolve(document.querySelector(selector));
        }

        const observer = new MutationObserver(mutations => {
            if (document.querySelector(selector)) {
                resolve(document.querySelector(selector));
                observer.disconnect();
            }
        });

        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    });
}

To use it:

waitForElm('.some-class').then(elm => console.log(elm.textContent));

or with async/await

const elm = await waitForElm('.some-classs')

Pointer arithmetic for void pointer in C

You can't do pointer arithmetic on void * types, for exactly this reason!

CodeIgniter - How to return Json response from controller

For CodeIgniter 4, you can use the built-in API Response Trait

Here's sample code for reference:

<?php namespace App\Controllers;

use CodeIgniter\API\ResponseTrait;

class Home extends BaseController
{
    use ResponseTrait;

    public function index()
    {
        $data = [
            'data' => 'value1',
            'data2' => 'value2',
        ];

        return $this->respond($data);
    }
}

How can I write data attributes using Angular?

About access

<ol class="viewer-nav">
    <li *ngFor="let section of sections" 
        [attr.data-sectionvalue]="section.value"
        (click)="get_data($event)">
        {{ section.text }}
    </li>  
</ol>

And

get_data(event) {
   console.log(event.target.dataset.sectionvalue)
}

Convert Map to JSON using Jackson

Using jackson, you can do it as follows:

    ObjectMapper mapper = new ObjectMapper();
    String clientFilterJson = "";
    try {
        clientFilterJson = mapper.writeValueAsString(filterSaveModel);
    } catch (IOException e) {
        e.printStackTrace();
    }

One-line list comprehension: if-else variants

x if y else z is the syntax for the expression you're returning for each element. Thus you need:

[ x if x%2 else x*100 for x in range(1, 10) ]

The confusion arises from the fact you're using a filter in the first example, but not in the second. In the second example you're only mapping each value to another, using a ternary-operator expression.

With a filter, you need:

[ EXP for x in seq if COND ]

Without a filter you need:

[ EXP for x in seq ]

and in your second example, the expression is a "complex" one, which happens to involve an if-else.

How to extract year and month from date in PostgreSQL without using to_char() function?

to_char(timestamp, 'YYYY-MM')

You say that the order is not "right", but I cannot see why it is wrong (at least until year 10000 comes around).

Why do we use arrays instead of other data structures?

Not all programs do the same thing or run on the same hardware.

This is usually the answer why various language features exist. Arrays are a core computer science concept. Replacing arrays with lists/matrices/vectors/whatever advanced data structure would severely impact performance, and be downright impracticable in a number of systems. There are any number of cases where using one of these "advanced" data collection objects should be used because of the program in question.

In business programming (which most of us do), we can target hardware that is relatively powerful. Using a List in C# or Vector in Java is the right choice to make in these situations because these structures allow the developer to accomplish the goals faster, which in turn allows this type of software to be more featured.

When writing embedded software or an operating system an array may often be the better choice. While an array offers less functionality, it takes up less RAM, and the compiler can optimize code more efficiently for look-ups into arrays.

I am sure I am leaving out a number of the benefits for these cases, but I hope you get the point.

Entity Framework 6 Code first Default value

Your model properties don't have to be 'auto properties' Even though that is easier. And the DefaultValue attribute is really only informative metadata The answer accepted here is one alternative to the constructor approach.

public class Track
{

    private const int DEFAULT_LENGTH = 400;
    private int _length = DEFAULT_LENGTH;
    [DefaultValue(DEFAULT_LENGTH)]
    public int LengthInMeters {
        get { return _length; }
        set { _length = value; }
    }
}

vs.

public class Track
{
    public Track()
    {
        LengthInMeters = 400;   
    }

    public int LengthInMeters { get; set; }        
}

This will only work for applications creating and consuming data using this specific class. Usually this isn't a problem if data access code is centralized. To update the value across all applications you need to configure the datasource to set a default value. Devi's answer shows how it can be done using migrations, sql, or whatever language your data source speaks.

How can I get the order ID in WooCommerce?

I didnt test it and dont know were you need it, but:

$order = new WC_Order(post->ID);
echo $order->get_order_number();

Let me know if it works. I belive order number echoes with the "#" but you can split that if only need only the number.

phpMyAdmin - Error > Incorrect format parameter?

Compress your .sql file, and make sure to name it .[format].[compression], i.e. database.sql.zip.

As noted above, PhpMyAdmin throws this error if your .sql file is larger than the Maximum allowed upload size -- but, in my case the maximum was 50MiB despite that I had set all options noted in previous answers (look for the "Max: 50MiB" next to the upload button in PhpMyAdmin).

Generate random colors (RGB)

Taking a uniform random variable as the value of RGB may generate a large amount of gray, white, and black, which are often not the colors we want.

The cv::applyColorMap can easily generate a random RGB palette, and you can choose a favorite color map from the list here

Example for C++11:

#include <algorithm>
#include <numeric>
#include <random>
#include <opencv2/opencv.hpp>

std::random_device rd;
std::default_random_engine re(rd());

// Generating randomized palette
cv::Mat palette(1, 255, CV_8U);
std::iota(palette.data, palette.data + 255, 0);
std::shuffle(palette.data, palette.data + 255, re);
cv::applyColorMap(palette, palette, cv::COLORMAP_JET);

// ...

// Picking random color from palette and drawing
auto randColor = palette.at<cv::Vec3b>(i % palette.cols);
cv::rectangle(img, cv::Rect(0, 0, 100, 100), randColor, -1);

Example for Python3:

import numpy as np, cv2

palette = np.arange(0, 255, dtype=np.uint8).reshape(1, 255, 1)
palette = cv2.applyColorMap(palette, cv2.COLORMAP_JET).squeeze(0)
np.random.shuffle(palette)
# ...

rand_color = tuple(palette[i % palette.shape[0]].tolist())
cv2.rectangle(img, (0, 0), (100, 100), rand_color, -1)

If you don't need so many colors, you can just cut the palette to the desired length.

How do I get the raw request body from the Request.Content object using .net 4 api endpoint

For other future users who do not want to make their controllers asynchronous, or cannot access the HttpContext, or are using dotnet core (this answer is the first I found on Google trying to do this), the following worked for me:

[HttpPut("{pathId}/{subPathId}"),
public IActionResult Put(int pathId, int subPathId, [FromBody] myViewModel viewModel)
{

    var body = new StreamReader(Request.Body);
    //The modelbinder has already read the stream and need to reset the stream index
    body.BaseStream.Seek(0, SeekOrigin.Begin); 
    var requestBody = body.ReadToEnd();
    //etc, we use this for an audit trail
}

git: How to diff changed files versus previous versions after a pull?

I like to use:

git diff HEAD^

Or if I only want to diff a specific file:

git diff HEAD^ -- /foo/bar/baz.txt

Identifying and solving javax.el.PropertyNotFoundException: Target Unreachable

I got stuck on this error because in the class that has the @SpringBootApplication I forgot to specify the controller's package name.

I wanted to be more specific this time pointing out which components Spring had to scan, instead of configuring the base package.

It was like this:

@ComponentScan(basePackages = {"br.com.company.project.repository", "br.com.company.project.service"})

But the correct form is one of these:

@ComponentScan(basePackages = {"br.com.company.project.repository", "br.com.company.project.service", "br.com.company.project.controller"})

@ComponentScan(basePackages = {"br.com.company.project")

I decided to share my solution, because although the correct answer is very comprehensive, it doesn't cover this (idiotic) mistake :)

Printing chars and their ASCII-code in C

Chars within single quote ('XXXXXX'), when printed as decimal should output its ASCII value.

int main(){

    printf("D\n");
    printf("The ASCII of D is %d\n",'D');

    return 0;

}

Output:

% ./a.out
>> D
>> The ASCII of D is 68

How to center form in bootstrap 3

if you insist on using Bootstrap, use d-inline-block like below

    <div class="row d-inline-block">
       <form class="form-inline">
         <div class="form-group d-inline-block">
           <input type="email" aria-expanded="false" class="form-control mr-2" 
               placeholder="Enter your email">
           <button type="button" class="btn btn-danger">submit</button>
         </div>
       </form>
     </div>

How to change a css class style through Javascript?

Since classList is supported in all major browsers and jQuery drops support for IE<9 (in 2.x branch as Stormblack points in the comment), considering this HTML

<div id="mydiv" class="oldclass">text</div>

you can comfortably use this syntax:

document.getElementById('mydiv').classList.add("newClass");

This will also result in:

<div id="mydiv" class="oldclass newclass">text</div>

plus you can also use remove, toggle, contains methods.

Using filesystem in node.js with async / await

Recommend using an npm package such as https://github.com/davetemplin/async-file, as compared to custom functions. For example:

import * as fs from 'async-file';

await fs.rename('/tmp/hello', '/tmp/world');
await fs.appendFile('message.txt', 'data to append');
await fs.access('/etc/passd', fs.constants.R_OK | fs.constants.W_OK);

var stats = await fs.stat('/tmp/hello', '/tmp/world');

Other answers are outdated

Repeat a task with a time delay?

There are 3 ways to do it:

Use ScheduledThreadPoolExecutor

A bit of overkill since you don't need a pool of Thread

   //----------------------SCHEDULER-------------------------
    private final ScheduledThreadPoolExecutor executor_ =
            new ScheduledThreadPoolExecutor(1);
     ScheduledFuture<?> schedulerFuture;
   public void  startScheduler() {
       schedulerFuture=  executor_.scheduleWithFixedDelay(new Runnable() {
            @Override
            public void run() {
                //DO YOUR THINGS
                pageIndexSwitcher.setVisibility(View.GONE);
            }
        }, 0L, 5*MILLI_SEC,  TimeUnit.MILLISECONDS);
    }


    public void  stopScheduler() {
        pageIndexSwitcher.setVisibility(View.VISIBLE);
        schedulerFuture.cancel(false);
        startScheduler();
    }

Use Timer Task

Old Android Style

    //----------------------TIMER  TASK-------------------------

    private Timer carousalTimer;
    private void startTimer() {
        carousalTimer = new Timer(); // At this line a new Thread will be created
        carousalTimer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                //DO YOUR THINGS
                pageIndexSwitcher.setVisibility(INVISIBLE);
            }
        }, 0, 5 * MILLI_SEC); // delay
    }

    void stopTimer() {
        carousalTimer.cancel();
    }

Use Handler and Runnable

Modern Android Style

    //----------------------HANDLER-------------------------

    private Handler taskHandler = new android.os.Handler();

    private Runnable repeatativeTaskRunnable = new Runnable() {
        public void run() {
            //DO YOUR THINGS
        }
    };

   void startHandler() {
        taskHandler.postDelayed(repeatativeTaskRunnable, 5 * MILLI_SEC);
    }

    void stopHandler() {
        taskHandler.removeCallbacks(repeatativeTaskRunnable);
    }

Non-Leaky Handler with Activity / Context

Declare an inner Handler class which does not leak Memory in your Activity/Fragment class

/**
     * Instances of static inner classes do not hold an implicit
     * reference to their outer class.
     */
    private static class NonLeakyHandler extends Handler {
        private final WeakReference<FlashActivity> mActivity;

        public NonLeakyHandler(FlashActivity activity) {
            mActivity = new WeakReference<FlashActivity>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            FlashActivity activity = mActivity.get();
            if (activity != null) {
                // ...
            }
        }
    }

Declare a runnable which will perform your repetitive task in your Activity/Fragment class

   private Runnable repeatativeTaskRunnable = new Runnable() {
        public void run() {
            new Handler(getMainLooper()).post(new Runnable() {
                @Override
                public void run() {

         //DO YOUR THINGS
        }
    };

Initialize Handler object in your Activity/Fragment (here FlashActivity is my activity class)

//Task Handler
private Handler taskHandler = new NonLeakyHandler(FlashActivity.this);

To repeat a task after fix time interval

taskHandler.postDelayed(repeatativeTaskRunnable , DELAY_MILLIS);

To stop the repetition of task

taskHandler .removeCallbacks(repeatativeTaskRunnable );

UPDATE: In Kotlin:

    //update interval for widget
    override val UPDATE_INTERVAL = 1000L

    //Handler to repeat update
    private val updateWidgetHandler = Handler()

    //runnable to update widget
    private var updateWidgetRunnable: Runnable = Runnable {
        run {
            //Update UI
            updateWidget()
            // Re-run it after the update interval
            updateWidgetHandler.postDelayed(updateWidgetRunnable, UPDATE_INTERVAL)
        }

    }

 // SATART updating in foreground
 override fun onResume() {
        super.onResume()
        updateWidgetHandler.postDelayed(updateWidgetRunnable, UPDATE_INTERVAL)
    }


    // REMOVE callback if app in background
    override fun onPause() {
        super.onPause()
        updateWidgetHandler.removeCallbacks(updateWidgetRunnable);
    }

How do I correct the character encoding of a file?

I found a simple way to auto-detect file encodings - change the file to a text file (on a mac rename the file extension to .txt) and drag it to a Mozilla Firefox window (or File -> Open). Firefox will detect the encoding - you can see what it came up with under View -> Character Encoding.

I changed my file's encoding using TextMate once I knew the correct encoding. File -> Reopen using encoding and choose your encoding. Then File -> Save As and change the encoding to UTF-8 and line endings to LF (or whatever you want)

Stopping an Android app from console

In eclipse go to the DDMS perspective and in the devices tab click the process you want to kill under the device you want to kill it on. You then just need to press the stop button and it should kill the process.

I'm not sure how you'd do this from the command line tool but there must be a way. Maybe you do it through the adb shell...

In bash, how to store a return value in a variable?

It's due to the echo statements. You could switch your echos to prints and return with an echo. Below works

#!/bin/bash

set -x
echo "enter: "
read input

function password_formula
{
        length=${#input}
        last_two=${input:length-2:length}
        first=`echo $last_two| sed -e 's/\(.\)/\1 /g'|awk '{print $2}'`
        second=`echo $last_two| sed -e 's/\(.\)/\1 /g'|awk '{print $1}'`
        let sum=$first+$second
        sum_len=${#sum}
        print $second
        print $sum

        if [ $sum -gt 9 ]
        then
           sum=${sum:1}
        fi

        value=$second$sum$first
        echo $value
}
result=$(password_formula)
echo $result

I want to vertical-align text in select box

So far this is working fine for me:

line-height: 100%;

Formatting floats without trailing zeros

Here's a solution that worked for me. It's a blend of the solution by PolyMesh and use of the new .format() syntax.

for num in 3, 3., 3.0, 3.1, 3.14, 3.140:
    print('{0:.2f}'.format(num).rstrip('0').rstrip('.'))

Output:

3
3
3
3.1
3.14
3.14

How do I draw a set of vertical lines in gnuplot?

Here is a snippet from my perl script to do this:

print OUTPUT "set arrow from $x1,$y1 to $x1,$y2 nohead lc rgb \'red\'\n";

As you might guess from above, it's actually drawn as a "headless" arrow.

Java: Rotating Images

A simple way to do it without the use of such a complicated draw statement:

    //Make a backup so that we can reset our graphics object after using it.
    AffineTransform backup = g2d.getTransform();
    //rx is the x coordinate for rotation, ry is the y coordinate for rotation, and angle
    //is the angle to rotate the image. If you want to rotate around the center of an image,
    //use the image's center x and y coordinates for rx and ry.
    AffineTransform a = AffineTransform.getRotateInstance(angle, rx, ry);
    //Set our Graphics2D object to the transform
    g2d.setTransform(a);
    //Draw our image like normal
    g2d.drawImage(image, x, y, null);
    //Reset our graphics object so we can draw with it again.
    g2d.setTransform(backup);

Upload failed You need to use a different version code for your APK because you already have one with version code 2

(For Flutter App) You need to use a different version code for your APK or Android App Bundle because you already have one with version code 1.

Don't be panic...

You need to change in Flutter Version from pubspec.yaml file and Version Code from local.properties file.

First go to your pubspec.yaml file. The first three lines should be name, description and version of App.

Before Release -

For you the version might look something like this:

version: 1.0.0+1

So before creating an apk for release (for update your exiting app on Google Play Console i.e for new update) make sure you increment this number by 1. (You should increment it as there's no requirement on increment step) .

Solution

Just change that version to (As per your need )

version: 1.0.1+2

And Second if

flutter.versionCode in Project -> android -> local.properties is

flutter.versionCode=1 then change it or upgrade it to the flutter.versionCode=2 or any other greater number than previous code.

And finally release the app as per documentation.

Using Selenium Web Driver to retrieve value of a HTML input

Following @ragzzy 's answer I use

 public static string Value(this IWebElement element, IJavaScriptExecutor javaScriptExecutor)
    {

        try
        {
            string value = javaScriptExecutor.ExecuteScript("return arguments[0].value", element) as string;
            return value;
        }
        catch (Exception)
        {
            return null;
        }
    }

It works quite well and does not alter the DOM

What is the difference between npm install and npm run build?

NPM in 2019

npm build no longer exists. You must call npm run build now. More info below.

TLDR;

npm install: installs dependencies, then calls the install from the package.json scripts field.

npm run build: runs the build field from the package.json scripts field.


NPM Scripts Field

https://docs.npmjs.com/misc/scripts

There are many things you can put into the npm package.json scripts field. Check out the documentation link above more above the lifecycle of the scripts - most have pre and post hooks that you can run scripts before/after install, publish, uninstall, test, start, stop, shrinkwrap, version.


To Complicate Things

  • npm install is not the same as npm run install
  • npm install installs package.json dependencies, then runs the package.json scripts.install
    • (Essentially calls npm run install after dependencies are installed.
  • npm run install only runs the package.json scripts.install, it will not install dependencies.
  • npm build used to be a valid command (used to be the same as npm run build) but it no longer is; it is now an internal command. If you run it you'll get: npm WARN build npm build called with no arguments. Did you mean to npm run-script build? You can read more on the documentation: https://docs.npmjs.com/cli/build

Extra Notes

There are still two top level commands that will run scripts, they are:

  • npm start which is the same as npm run start
  • npm test ==> npm run test

Calculate percentage Javascript

Heres another approach.

HTML:

<input type='text' id="pointspossible" class="clsInput" />
<input type='text' id="pointsgiven"  class="clsInput" />
<button id="btnCalculate">Calculate</button>
<input type='text' id="pointsperc" disabled/>

JS Code:

function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}


$('#btnCalculate').on('click', function() {
    var a = $('#pointspossible').val().replace(/ +/g, "");
    var b = $('#pointsgiven').val().replace(/ +/g, "");
    var perc = "0";
    if (a.length > 0 && b.length > 0) {
        if (isNumeric(a) && isNumeric(b)) {
            perc = a / b * 100;
        }
    }    
    $('#pointsperc').val(perc).toFixed(3);
});

Live Sample: Percentage Calculator

Set EditText cursor color

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">#36f0ff</item>
    <item name="colorPrimaryDark">#007781</item>
    <item name="colorAccent">#000</item>
</style>

<style name="AppTheme.NoActionBar">
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
</style>

<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

<style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

change t he color of colorAccent in styles.xm, that's it simple

Starting with Zend Tutorial - Zend_DB_Adapter throws Exception: "SQLSTATE[HY000] [2002] No such file or directory"

It looks like mysql service is either not working or stopped. you can start it by using below command (in Ubuntu):

service mysql start

It should work! If you are using any other operating system than Ubuntu then use appropriate way to start mysql

java.lang.NoSuchMethodError: javax.servlet.ServletContext.getContextPath()Ljava/lang/String;

java.lang.NoSuchMethodError: javax.servlet.ServletContext.getContextPath()Ljava/lang/String;

That method was added in Servlet 2.5.

So this problem can have at least 3 causes:

  1. The servlet container does not support Servlet 2.5.
  2. The web.xml is not declared conform Servlet 2.5 or newer.
  3. The webapp's runtime classpath is littered with servlet container specific JAR files of a different servlet container make/version which does not support Servlet 2.5.

To solve it,

  1. Make sure that your servlet container supports at least Servlet 2.5. That are at least Tomcat 6, Glassfish 2, JBoss AS 4.1, etcetera. Tomcat 5.5 for example supports at highest Servlet 2.4. If you can't upgrade Tomcat, then you'd need to downgrade Spring to a Servlet 2.4 compatible version.
  2. Make sure that the root declaration of web.xml complies Servlet 2.5 (or newer, at least the highest whatever your target runtime supports). For an example, see also somewhere halfway our servlets wiki page.
  3. Make sure that you don't have any servlet container specific libraries like servlet-api.jar or j2ee.jar in /WEB-INF/lib or even worse, the JRE/lib or JRE/lib/ext. They do not belong there. This is a pretty common beginner's mistake in an attempt to circumvent compilation errors in an IDE, see also How do I import the javax.servlet API in my Eclipse project?.

Make a div fill the height of the remaining screen space

Used: height: calc(100vh - 110px);

code:

_x000D_
_x000D_
  _x000D_
.header { height: 60px; top: 0; background-color: green}_x000D_
.body {_x000D_
    height: calc(100vh - 110px); /*50+60*/_x000D_
    background-color: gray;_x000D_
}_x000D_
.footer { height: 50px; bottom: 0; }_x000D_
  
_x000D_
<div class="header">_x000D_
    <h2>My header</h2>_x000D_
</div> _x000D_
<div class="body">_x000D_
    <p>The body</p>_x000D_
</div> _x000D_
<div class="footer">_x000D_
    My footer_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to catch a unique constraint error in a PL/SQL block?

EXCEPTION
      WHEN DUP_VAL_ON_INDEX
      THEN
         UPDATE

List the queries running on SQL Server

I would suggest querying the sys views. something similar to

SELECT * 
FROM 
   sys.dm_exec_sessions s
   LEFT  JOIN sys.dm_exec_connections c
        ON  s.session_id = c.session_id
   LEFT JOIN sys.dm_db_task_space_usage tsu
        ON  tsu.session_id = s.session_id
   LEFT JOIN sys.dm_os_tasks t
        ON  t.session_id = tsu.session_id
        AND t.request_id = tsu.request_id
   LEFT JOIN sys.dm_exec_requests r
        ON  r.session_id = tsu.session_id
        AND r.request_id = tsu.request_id
   OUTER APPLY sys.dm_exec_sql_text(r.sql_handle) TSQL

This way you can get a TotalPagesAllocated which can help you figure out the spid that is taking all the server resources. There has lots of times when I can't even bring up activity monitor and use these sys views to see what's going on.

I would recommend you reading the following article. I got this reference from here.

Exercises to improve my Java programming skills

You could try the problems at RosettaCode, many of which lack Java solutions at the moment. The problems are of many different difficulties, but each has a solution already in another language which should help with the algorithmic side.

Run a Docker image as a container

Since you have created an image from the Dockerfile, the image currently is not in active state. In order to work you need to run this image inside a container.

The $ docker images command describes how many images are currently available in the local repository. and

docker ps -a

shows how many containers are currently available, i.e. the list of active and exited containers.

There are two ways to run the image in the container:

$ docker run [OPTIONS] IMAGE[:TAG|@DIGEST] [COMMAND] [ARG...]

In detached mode:

-d=false: Detached mode: Run container in the background, print new container id

In interactive mode:

-i :Keep STDIN open even if not attached

Here is the Docker run command

$ docker run image_name:tag_name

For more clarification on Docker run, you can visit Docker run reference.

It's the best material to understand Docker.

Error creating bean with name

It looks like your Spring component scan Base is missing UserServiceImpl

<context:component-scan base-package="org.assessme.com.controller." />

document.getElementById("remember").visibility = "hidden"; not working on a checkbox

you can use

style="display:none"

Ex:

<asp:TextBox ID="txbProv" runat="server" style="display:none"></asp:TextBox>

Java program to find the largest & smallest number in n numbers without using arrays

import java.util.Scanner;

public class LargestSmallestNum {

    public void findLargestSmallestNo() {

        int smallest = Integer.MAX_VALUE;
        int large = 0;
        int num;

        System.out.println("enter the number");

        Scanner input = new Scanner(System.in);

        int n = input.nextInt();

        for (int i = 0; i < n; i++) {

            num = input.nextInt();

            if (num > large)
                large = num;

            if (num < smallest)
                smallest = num;

            System.out.println("the largest is:" + large);
            System.out.println("Smallest no is : "  + smallest);
        }
    }

    public static void main(String...strings){
        LargestSmallestNum largestSmallestNum = new LargestSmallestNum();
        largestSmallestNum.findLargestSmalestNo();
    }
}

How do I install Python packages on Windows?

You can also just download and run ez_setup.py, though the SetupTools documentation no longer suggests this. Worked fine for me as recently as 2 weeks ago.

Python extending with - using super() Python 3 vs Python 2

  • super() (without arguments) was introduced in Python 3 (along with __class__):

    super() -> same as super(__class__, self)
    

    so that would be the Python 2 equivalent for new-style classes:

    super(CurrentClass, self)
    
  • for old-style classes you can always use:

     class Classname(OldStyleParent):
        def __init__(self, *args, **kwargs):
            OldStyleParent.__init__(self, *args, **kwargs)
    

CSS "and" and "or"

&& works by stringing-together multiple selectors like-so:

<div class="class1 class2"></div>

div.class1.class2
{
  /* foo */
}

Another example:

<input type="radio" class="class1" />

input[type="radio"].class1
{
  /* foo */
}

|| works by separating multiple selectors with commas like-so:

<div class="class1"></div>
<div class="class2"></div>

div.class1,
div.class2
{
  /* foo */
}

Eclipse: stop code from running (java)

For newer versions of Eclipse:

  1. open the Debug perspective (Window > Open Perspective > Debug)

  2. select process in Devices list (bottom right)

  3. Hit Stop button (top right of Devices pane)

Using subprocess to run Python script on Windows

Just found sys.executable - the full path to the current Python executable, which can be used to run the script (instead of relying on the shbang, which obviously doesn't work on Windows)

import sys
import subprocess

theproc = subprocess.Popen([sys.executable, "myscript.py"])
theproc.communicate()

Chmod 777 to a folder and all contents

If you are going for a console command it would be:

chmod -R 777 /www/store. The -R (or --recursive) options make it recursive.

Or if you want to make all the files in the current directory have all permissions type:

chmod -R 777 ./

If you need more info about chmod command see: File permission

Quick easy way to migrate SQLite3 to MySQL?

Probably the quick easiest way is using the sqlite .dump command, in this case create a dump of the sample database.

sqlite3 sample.db .dump > dump.sql

You can then (in theory) import this into the mysql database, in this case the test database on the database server 127.0.0.1, using user root.

mysql -p -u root -h 127.0.0.1 test < dump.sql

I say in theory as there are a few differences between grammars.

In sqlite transactions begin

BEGIN TRANSACTION;
...
COMMIT;

MySQL uses just

BEGIN;
...
COMMIT;

There are other similar problems (varchars and double quotes spring back to mind) but nothing find and replace couldn't fix.

Perhaps you should ask why you are migrating, if performance/ database size is the issue perhaps look at reoginising the schema, if the system is moving to a more powerful product this might be the ideal time to plan for the future of your data.

Jersey stopped working with InjectionManagerFactory not found

The only way I could solve it was via:

org.glassfish.jersey.core jersey-server ${jersey-2-version}

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>${jersey-2-version}</version>
</dependency>

<dependency>
    <groupId>org.glassfish.jersey.inject</groupId>
    <artifactId>jersey-hk2</artifactId>
    <version>${jersey-2-version}</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.glassfish.jersey.core/jersey-common -->
<dependency>
    <groupId>org.glassfish.jersey.core</groupId>
    <artifactId>jersey-common</artifactId>
    <version>${jersey-2-version}</version>
</dependency>

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet-core</artifactId>
    <version>${jersey-2-version}</version>
</dependency>

So, only if I added jersey-container-servlet and jersey-hk2 would it run without errors

How to create a popup windows in javafx

You can either create a new Stage, add your controls into it or if you require the POPUP as Dialog box, then you may consider using DialogsFX or ControlsFX(Requires JavaFX8)

For creating a new Stage, you can use the following snippet

@Override
public void start(final Stage primaryStage) {
    Button btn = new Button();
    btn.setText("Open Dialog");
    btn.setOnAction(
        new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                final Stage dialog = new Stage();
                dialog.initModality(Modality.APPLICATION_MODAL);
                dialog.initOwner(primaryStage);
                VBox dialogVbox = new VBox(20);
                dialogVbox.getChildren().add(new Text("This is a Dialog"));
                Scene dialogScene = new Scene(dialogVbox, 300, 200);
                dialog.setScene(dialogScene);
                dialog.show();
            }
         });
    }

If you don't want it to be modal (block other windows), use:

dialog.initModality(Modality.NONE);

Powershell: How can I stop errors from being displayed in a script?

If you want the powershell errormessage for a cmdlet suppressed, but still want to catch the error, use "-erroraction 'silentlyStop'"

Is there a CSS selector by class prefix?

This is not possible with CSS selectors. But you could use two classes instead of one, e.g. status and important instead of status-important.

How can I display my windows user name in excel spread sheet using macros?

Range("A1").value = Environ("Username")

This is better than Application.Username, which doesn't always supply the Windows username. Thanks to Kyle for pointing this out.

  • Application Username is the name of the User set in Excel > Tools > Options
  • Environ("Username") is the name you registered for Windows; see Control Panel >System

Angular 5 Reactive Forms - Radio Button Group

IF you want to derive usg Boolean true False need to add "[]" around value

<form [formGroup]="form">
  <input type="radio" [value]=true formControlName="gender" >Male
  <input type="radio" [value]=false formControlName="gender">Female
</form>

How I can filter a Datatable?

use it:

.CopyToDataTable()

example:

string _sqlWhere = "Nachname = 'test'";
string _sqlOrder = "Nachname DESC";

DataTable _newDataTable = yurDateTable.Select(_sqlWhere, _sqlOrder).CopyToDataTable();

Define variable to use with IN operator (T-SQL)

I think you'll have to declare a string and then execute that SQL string.

Have a look at sp_executeSQL

Invalid attempt to read when no data is present

I just had this error, I was calling dr.NextResult() instead of dr.Read().

how to access iFrame parent page using jquery?

how to access iFrame parent page using jquery

window.parent.document.

jQuery is a library on top of JavaScript, not a complete replacement for it. You don't have to replace every last JavaScript expression with something involving $.

Calling the base class constructor from the derived class constructor

First off, a PetStore is not a farm.

Let's get past this though. You actually don't need access to the private members, you have everything you need in the public interface:

Animal_* getAnimal_(int i);
void addAnimal_(Animal_* newAnimal);

These are the methods you're given access to and these are the ones you should use.

I mean I did this Inheritance so I can add animals to my PetStore but now since sizeF is private how can I do that ??

Simple, you call addAnimal. It's public and it also increments sizeF.

Also, note that

PetStore()
{
 idF=0;
};

is equivalent to

PetStore() : Farm()
{
 idF=0;
};

i.e. the base constructor is called, base members are initialized.

Git: "Not currently on any branch." Is there an easy way to get back on a branch, while keeping the changes?

The following method may work:

git rebase HEAD master
git checkout master

This will rebase your current HEAD changes on top of the master. Then you can switch the branch.


Alternative way is to checkout the branch first:

git checkout master

Then Git should display SHA1 of your detached commits, then you can cherry pick them, e.g.

git cherry-pick YOURSHA1

Or you can also merge the latest one:

git merge YOURSHA1

To see all of your commits from different branches (to make sure you've them), run: git reflog.

How do you tell if a checkbox is selected in Selenium for Java?

For the event where there are multiple check-boxes from which you'd like to select/deselect only a few, the following work with the Chrome Driver (somehow failed for IE Driver):

NOTE: My check-boxes didn't have an ID associated with them, which would be the best way to identify them according to the Documentation. Note the ! sign at the beginning of the statement.

if(!driver.findElement(By.xpath("//input[@type='checkbox' and @name='<name>']")).isSelected()) 
{
  driver.findElement(By.xpath("//input[@type='checkbox' and @name= '<name>']")).click();
}

Force div element to stay in same place, when page is scrolled

You can do this replacing position:absolute; by position:fixed;.

How to sum a list of integers with java streams?

This will work, but the i -> i is doing some automatic unboxing which is why it "feels" strange. Either of the following will work and better explain what the compiler is doing under the hood with your original syntax:

integers.values().stream().mapToInt(i -> i.intValue()).sum();
integers.values().stream().mapToInt(Integer::intValue).sum();

How to view data saved in android database(SQLite)?

You can access this folder using the DDMS for your Emulator. you can't access this location on a real device unless you have a rooted device.

You can view Table structure and Data in Eclipse. Here are the steps

  1. Install SqliteManagerPlugin for Eclipse. Jump to step 5 if you already have it.
  2. Download the *.jar file from here
  3. Put the *.jar file into the folder eclipse/dropins/
  4. Restart eclipse
  5. In the top right of eclipse, click the DDMS icon
  6. Select the proper emulator in the left panel
  7. In the File Explorer tab on the main panel, go to /data/data/[YOUR.APP.NAMESPACE]/databases
  8. Underneath the DDMS icon, there should be a new blue icon of a Database light up when you select your database. Click it and you will see a Questoid Sqlite Manager tab open up to view your data.

*Note: If the database doesn't light up, it may be because your database doesn't have a *.db file extension. Be sure your database is called [DATABASE_NAME].db

*Note: if you want to use a DB without .db-Extension:

  1. Download this Questoid SqLiteBrowser: http://www.java2s.com/Code/JarDownload/com.questoid/com.questoid.sqlitebrowser_1.2.0.jar.zip

  2. Unzip and put it into eclipse/dropins (not Plugins)

Check this for more information

Adding external library into Qt Creator project

Are you using qmake projects? If so, you can add an external library using the LIBS variable. E.g:

win32:LIBS += path/to/Psapi.lib

Find the most popular element in int[] array

You can count the occurrences of the different numbers, then look for the highest one. This is an example that uses a Map, but could relatively easily be adapted to native arrays.

Second largest element: Let us take example : [1,5,4,2,3] in this case, Second largest element will be 4.

  1. Sort the Array in descending order, once the sort done output will be A = [5,4,3,2,1]

  2. Get the Second Largest Element from the sorted array Using Index 1. A[1] -> Which will give the Second largest element 4.

private static int getMostOccuringElement(int[] A) { Map occuringMap = new HashMap();

    //count occurences
    for (int i = 0; i < A.length; i++) { 
        if (occuringMap.get(A[i]) != null) {
            int val = occuringMap.get(A[i]) + 1;
            occuringMap.put(A[i], val);
        } else {
            occuringMap.put(A[i], 1);
        }
    }

    //find maximum occurence
    int max = Integer.MIN_VALUE; 
    int element = -1;
    for (Map.Entry<Integer, Integer> entry : occuringMap.entrySet()) {
        if (entry.getValue() > max) {
            max = entry.getValue();
            element = entry.getKey();
        }
    }
    return element;
}

What is the difference between .*? and .* regular expressions?

It is the difference between greedy and non-greedy quantifiers.

Consider the input 101000000000100.

Using 1.*1, * is greedy - it will match all the way to the end, and then backtrack until it can match 1, leaving you with 1010000000001.
.*? is non-greedy. * will match nothing, but then will try to match extra characters until it matches 1, eventually matching 101.

All quantifiers have a non-greedy mode: .*?, .+?, .{2,6}?, and even .??.

In your case, a similar pattern could be <([^>]*)> - matching anything but a greater-than sign (strictly speaking, it matches zero or more characters other than > in-between < and >).

See Quantifier Cheat Sheet.

How can I access my localhost from my Android device?

This solution is usable when your mobile device and computer is not in same network:

You need to use port forwarding in this case. In the Google chrome inspect window (chrome://inspect) You can see the connected devices. enter image description here

Click on the port fowading button, and set a random port say 3000 to the port which your laptop uses say 8080.

enter image description here

now use localhost:3000 from device to access the localhost:8080(or_whatever_ip:portno) in the laptop. You can check it in the mobile browser. Try localhost:3000 in the mobile browser. Make sure to check the "Enable port forwarding" checkbox in the "Port forwarding settings" window

How to fix "Incorrect string value" errors?

I solved this problem today by altering the column to 'LONGBLOB' type which stores raw bytes instead of UTF-8 characters.

The only disadvantage of doing this is that you have to take care of the encoding yourself. If one client of your application uses UTF-8 encoding and another uses CP1252, you may have your emails sent with incorrect characters. To avoid this, always use the same encoding (e.g. UTF-8) across all your applications.

Refer to this page http://dev.mysql.com/doc/refman/5.0/en/blob.html for more details of the differences between TEXT/LONGTEXT and BLOB/LONGBLOB. There are also many other arguments on the web discussing these two.

UnicodeEncodeError: 'charmap' codec can't encode - character maps to <undefined>, print function

I see three solutions to this:

  1. Change the output encoding, so it will always output UTF-8. See e.g. Setting the correct encoding when piping stdout in Python, but I could not get these example to work.

  2. Following example code makes the output aware of your target charset.

    # -*- coding: utf-8 -*-
    import sys
    
    print sys.stdout.encoding
    print u"Stöcker".encode(sys.stdout.encoding, errors='replace')
    print u"????????".encode(sys.stdout.encoding, errors='replace')
    

    This example properly replaces any non-printable character in my name with a question mark.

    If you create a custom print function, e.g. called myprint, using that mechanisms to encode output properly you can simply replace print with myprint whereever necessary without making the whole code look ugly.

  3. Reset the output encoding globally at the begin of the software:

    The page http://www.macfreek.nl/memory/Encoding_of_Python_stdout has a good summary what to do to change output encoding. Especially the section "StreamWriter Wrapper around Stdout" is interesting. Essentially it says to change the I/O encoding function like this:

    In Python 2:

    if sys.stdout.encoding != 'cp850':
      sys.stdout = codecs.getwriter('cp850')(sys.stdout, 'strict')
    if sys.stderr.encoding != 'cp850':
      sys.stderr = codecs.getwriter('cp850')(sys.stderr, 'strict')
    

    In Python 3:

    if sys.stdout.encoding != 'cp850':
      sys.stdout = codecs.getwriter('cp850')(sys.stdout.buffer, 'strict')
    if sys.stderr.encoding != 'cp850':
      sys.stderr = codecs.getwriter('cp850')(sys.stderr.buffer, 'strict')
    

    If used in CGI outputting HTML you can replace 'strict' by 'xmlcharrefreplace' to get HTML encoded tags for non-printable characters.

    Feel free to modify the approaches, setting different encodings, .... Note that it still wont work to output non-specified data. So any data, input, texts must be correctly convertable into unicode:

    # -*- coding: utf-8 -*-
    import sys
    import codecs
    sys.stdout = codecs.getwriter("iso-8859-1")(sys.stdout, 'xmlcharrefreplace')
    print u"Stöcker"                # works
    print "Stöcker".decode("utf-8") # works
    print "Stöcker"                 # fails
    

How to correctly dismiss a DialogFragment?

There are references to the official docs (DialogFragment Reference) in other answers, but no mention of the example given there:

void showDialog() {
    mStackLevel++;

    // DialogFragment.show() will take care of adding the fragment
    // in a transaction.  We also want to remove any currently showing
    // dialog, so make our own transaction and take care of that here.
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    Fragment prev = getFragmentManager().findFragmentByTag("dialog");
    if (prev != null) {
        ft.remove(prev);
    }
    ft.addToBackStack(null);

    // Create and show the dialog.
    DialogFragment newFragment = MyDialogFragment.newInstance(mStackLevel);
    newFragment.show(ft, "dialog");
}

This removes any currently shown dialog, creates a new DialogFragment with an argument, and shows it as a new state on the back stack. When the transaction is popped, the current DialogFragment and its Dialog will be destroyed, and the previous one (if any) re-shown. Note that in this case DialogFragment will take care of popping the transaction of the Dialog is dismissed separately from it.

For my needs I changed it to:

FragmentManager manager = getSupportFragmentManager();
Fragment prev = manager.findFragmentByTag(TAG);
if (prev != null) {
    manager.beginTransaction().remove(prev).commit();
}

MyDialogFragment fragment = new MyDialogFragment();
fragment.show(manager, TAG);

What are native methods in Java and where should they be used?

Java native code necessities:

  • h/w access and control.
  • use of commercial s/w and system services[h/w related].
  • use of legacy s/w that hasn't or cannot be ported to Java.
  • Using native code to perform time-critical tasks.

hope these points answers your question :)

Finding elements not in a list

Your code is a no-op. By the definition of the loop, "item" has to be in Z. A "For ... in" loop in Python means "Loop though the list called 'z', each time you loop, give me the next item in the list, and call it 'item'"

http://docs.python.org/tutorial/controlflow.html#for-statements

I think your confusion arises from the fact that you're using the variable name "item" twice, to mean two different things.

OnChange event handler for radio button (INPUT type="radio") doesn't work as one value

<input type="radio" name="brd" onclick="javascript:brd();" value="IN">   
<input type="radio" name="brd" onclick="javascript:brd();" value="EX">` 
<script type="text/javascript">
  function brd() {alert($('[name="brd"]:checked').val());}
</script>

Where can I download an offline installer of Cygwin?

If all you want is the UNIX command line tools I'd suggest not installing Cygwin. Cygwin wants to turn your Windows PC into a UNIX Workstation which is why it likes to install all its packages.

Have a look at GnuWin32 instead. It's Windows ports of the command line tools and nothing else. Here is the installer for the GnuWin32 diff.exe. There are offline installers for all the common tools.

(You asked for offline installers but in case you ever want one later there is a tool which will download and install everything for you.)

Method 2: make an offline install zip file for cygwin.

Don't mess with saving packages because the installed directory for cygwin can be canned in a zip file and expanded whenever you need it on any computer.

  1. Download Cygwin installer

  2. pick packages you want installed from gui.

  3. hit install and wait a really long time for everything to download.

  4. zip up the C:\Cygwin folder. Now you have your offline zip file for installing cygwin on any machine.

  5. Unzip this file on whatever computer you like. set cmd.exe paths appropriately to point to cygwin bin directory under windows control panel.

How to upgrade docker-compose to latest version

If the above methods aren't working for you, then refer to this answer: https://stackoverflow.com/a/40554985

curl -L "https://github.com/docker/compose/releases/download/1.22.0/docker-compose-$(uname -s)-$(uname -m)" > ./docker-compose
sudo mv ./docker-compose /usr/bin/docker-compose
sudo chmod +x /usr/bin/docker-compose

GSON throwing "Expected BEGIN_OBJECT but was BEGIN_ARRAY"?

Alternative could be

to make your response look like

myCustom_JSONResponse

{"master":[
   {
      "updated_at":"2012-03-02 21:06:01",
      "fetched_at":"2012-03-02 21:28:37.728840",
      "description":null,
      "language":null,
      "title":"JOHN",
      "url":"http://rus.JOHN.JOHN/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f4791da203d0c2d76000035",
      "modified":"2012-03-02 23:28:58.840076"
   },
   {
      "updated_at":"2012-03-02 14:07:44",
      "fetched_at":"2012-03-02 21:28:37.033108",
      "description":null,
      "language":null,
      "title":"PETER",
      "url":"http://PETER.PETER.lv/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f476f61203d0c2d89000253",
      "modified":"2012-03-02 23:28:57.928001"
   }
]
}

instead of

server_JSONResponse

[
   {
      "updated_at":"2012-03-02 21:06:01",
      "fetched_at":"2012-03-02 21:28:37.728840",
      "description":null,
      "language":null,
      "title":"JOHN",
      "url":"http://rus.JOHN.JOHN/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f4791da203d0c2d76000035",
      "modified":"2012-03-02 23:28:58.840076"
   },
   {
      "updated_at":"2012-03-02 14:07:44",
      "fetched_at":"2012-03-02 21:28:37.033108",
      "description":null,
      "language":null,
      "title":"PETER",
      "url":"http://PETER.PETER.lv/rss.php",
      "icon_url":null,
      "logo_url":null,
      "id":"4f476f61203d0c2d89000253",
      "modified":"2012-03-02 23:28:57.928001"
   }
]

CODE

  String server_JSONResponse =.... // the string in which you are getting your JSON Response after hitting URL
String myCustom_JSONResponse="";// in which we will keep our response after adding object element to it
     MyClass apiResponse = new MyClass();

     myCustom_JSONResponse="{\"master\":"+server_JSONResponse+"}";



    apiResponse = gson.fromJson(myCustom_JSONResponse, MyClass .class);

After this it will be just any other GSON Parsing

How do I change column default value in PostgreSQL?

If you want to remove the default value constraint, you can do:

ALTER TABLE <table> ALTER COLUMN <column> DROP DEFAULT;

How to disable sort in DataGridView?

For extending control functionality like this, I like to use extension methods so that it can be reused easily. Here is a starter extensions file that contains an extension to disable sorting on a datagridview.

To use it, just include it in your project and call like this

myDatagridView.DisableSorting()

In my case, I added this line of code in the DataBindingComplete eventhandler of the DataGridView where I wanted sorting disabled

Imports System.ComponentModel
Imports System.Reflection
Imports System.Runtime.CompilerServices
Imports System.Windows.Forms

Public Module Extensions

<Extension()>
Public Sub DisableSorting(datagrid As DataGridView)
    For index = 0 To datagrid.Columns.Count - 1
        datagrid.Columns(index).SortMode = DataGridViewColumnSortMode.NotSortable
    Next
End Sub


End Module

PHP float with 2 decimal places: .00

0.00 is actually 0. If you need to have the 0.00 when you echo, simply use number_format this way:

number_format($number, 2);

Find object in list that has attribute equal to some value (that meets any condition)

For below code, xGen is an anonomous generator expression, yFilt is a filter object. Note that for xGen the additional None parameter is returned rather than throwing StopIteration when the list is exhausted.

arr =((10,0), (11,1), (12,2), (13,2), (14,3))

value = 2
xGen = (x for x in arr if x[1] == value)
yFilt = filter(lambda x: x[1] == value, arr)
print(type(xGen))
print(type(yFilt))

for i in range(1,4):
    print('xGen: pass=',i,' result=',next(xGen,None))
    print('yFilt: pass=',i,' result=',next(yFilt))

Output:

<class 'generator'>
<class 'filter'>
xGen: pass= 1  result= (12, 2)
yFilt: pass= 1  result= (12, 2)
xGen: pass= 2  result= (13, 2)
yFilt: pass= 2  result= (13, 2)
xGen: pass= 3  result= None
Traceback (most recent call last):
  File "test.py", line 12, in <module>
    print('yFilt: pass=',i,' result=',next(yFilt))
StopIteration

Hashcode and Equals for Hashset

Because in 2nd case you adding same reference twice and HashSet have check against this in HashMap.put() on which HashSet is based:

        if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
            V oldValue = e.value;
            e.value = value;
            e.recordAccess(this);
            return oldValue;
        }

As you can see, equals will be called only if hash of key being added equals to the key already present in set and references of these two are different.

Hibernate Query By Example and Projections

Can I see your User class? This is just using restrictions below. I don't see why Restrictions would be really any different than Examples (I think null fields get ignored by default in examples though).

getCurrentSession().createCriteria(User.class)
.setProjection( Projections.distinct( Projections.projectionList()
.add( Projections.property("name"), "name")
.add( Projections.property("city"), "city")))
.add( Restrictions.eq("city", "TEST")))
.setResultTransformer(Transformers.aliasToBean(User.class))
.list();

I've never used the alaistToBean, but I just read about it. You could also just loop over the results..

List<Object> rows = criteria.list();
for(Object r: rows){
  Object[] row = (Object[]) r;
  Type t = ((<Type>) row[0]);
}

If you have to you can manually populate User yourself that way.

Its sort of hard to look into the issue without some more information to diagnose the issue.

How to "select distinct" across multiple data frame columns in pandas?

There is no unique method for a df, if the number of unique values for each column were the same then the following would work: df.apply(pd.Series.unique) but if not then you will get an error. Another approach would be to store the values in a dict which is keyed on the column name:

In [111]:
df = pd.DataFrame({'a':[0,1,2,2,4], 'b':[1,1,1,2,2]})
d={}
for col in df:
    d[col] = df[col].unique()
d

Out[111]:
{'a': array([0, 1, 2, 4], dtype=int64), 'b': array([1, 2], dtype=int64)}

How to get Url Hash (#) from server side

Possible solution for GET requests:

New Link format: http://example.com/yourDirectory?hash=video01

Call this function toward top of controller or http://example.com/yourDirectory/index.php:

function redirect()
{
    if (!empty($_GET['hash'])) {
        /** Sanitize & Validate $_GET['hash']
               If valid return string
               If invalid: return empty or false
        ******************************************************/
        $validHash = sanitizeAndValidateHashFunction($_GET['hash']);
        if (!empty($validHash)) {
            $url = './#' . $validHash;
        } else {
            $url = '/your404page.php';
        }
        header("Location: $url");
    }
}

MySQL JOIN ON vs USING?

Wikipedia has the following information about USING:

The USING construct is more than mere syntactic sugar, however, since the result set differs from the result set of the version with the explicit predicate. Specifically, any columns mentioned in the USING list will appear only once, with an unqualified name, rather than once for each table in the join. In the case above, there will be a single DepartmentID column and no employee.DepartmentID or department.DepartmentID.

Tables that it was talking about:

enter image description here

The Postgres documentation also defines them pretty well:

The ON clause is the most general kind of join condition: it takes a Boolean value expression of the same kind as is used in a WHERE clause. A pair of rows from T1 and T2 match if the ON expression evaluates to true.

The USING clause is a shorthand that allows you to take advantage of the specific situation where both sides of the join use the same name for the joining column(s). It takes a comma-separated list of the shared column names and forms a join condition that includes an equality comparison for each one. For example, joining T1 and T2 with USING (a, b) produces the join condition ON T1.a = T2.a AND T1.b = T2.b.

Furthermore, the output of JOIN USING suppresses redundant columns: there is no need to print both of the matched columns, since they must have equal values. While JOIN ON produces all columns from T1 followed by all columns from T2, JOIN USING produces one output column for each of the listed column pairs (in the listed order), followed by any remaining columns from T1, followed by any remaining columns from T2.

How to enter a series of numbers automatically in Excel

Enter the first in the series and select that cell, then series fill (HOME > Editing - Fill, Series..., Columns):

SO8615149 example

It is very fast and the results are values not formulae.

Angular 4 img src is not found

<img src="images/no-record-found.png" width="50%" height="50%"/>

Your images folder and your index.html should be in same directory(follow following dir structure). it will even work after build

Directory Structure

-src
    |-images
    |-index.html
    |-app 

How do I install Python 3 on an AWS EC2 instance?

As of Amazon Linux version 2017.09 python 3.6 is now available:

sudo yum install python36 python36-virtualenv python36-pip

See the Release Notes for more info and other packages

How to force child div to be 100% of parent div's height without specifying parent's height?

using jQuery:

$(function() {
    function unifyHeights() {
        var maxHeight = 0;
        $('#container').children('#navigation, #content').each(function() {
            var height = $(this).outerHeight();
            // alert(height);
            if ( height > maxHeight ) {
                maxHeight = height;
            }
        });
        $('#navigation, #content').css('height', maxHeight);
    }
    unifyHeights();
});

How to loop through a dataset in powershell?

Here's a practical example (build a dataset from your current location):

$ds = new-object System.Data.DataSet
$ds.Tables.Add("tblTest")
[void]$ds.Tables["tblTest"].Columns.Add("Name",[string])
[void]$ds.Tables["tblTest"].Columns.Add("Path",[string])

dir | foreach {
    $dr = $ds.Tables["tblTest"].NewRow()
    $dr["Name"] = $_.name
    $dr["Path"] = $_.fullname
    $ds.Tables["tblTest"].Rows.Add($dr)
}


$ds.Tables["tblTest"]

$ds.Tables["tblTest"] is an object that you can manipulate just like any other Powershell object:

$ds.Tables["tblTest"] | foreach {
    write-host 'Name value is : $_.name
    write-host 'Path value is : $_.path
}

How to check if a variable is not null?

The two conditional statements you list here are not better than one another. Your usage depends on the situation. You have a typo by the way in the 2nd example. There should be only one equals sign after the exclamation mark.

The 1st example determines if the value in myVar is true and executes the code inside of the {...}

The 2nd example evaluates if myVar does not equal null and if that case is true it will execute your code inside of the {...}

I suggest taking a look into conditional statements for more techniques. Once you are familiar with them, you can decide when you need them.

A non well formed numeric value encountered

This helped me a lot -

$new_date = date_format(date_create($old_date), 'Y-m-d');

Here, date_create() provides you a date object for a given date & date_format() will set it in a given format.

for example,

<?php
    $date = date_create("13-02-2013");  // DateTime Object ( [date] => 2013-02-13 00:00:00.000000 [timezone_type] => 3 [timezone] => America/New_York )
    echo date_format($date,"Y-m-d");    // 2013-02-13
?>

TSQL Default Minimum DateTime

Sometimes you inherit brittle code that is already expecting magic values in a lot of places. Everyone is correct, you should use NULL if possible. However, as a shortcut to make sure every reference to that value is the same, I like to put "constants" (for lack of a better name) in SQL in a scaler function and then call that function when I need the value. That way if I ever want to update them all to be something else, I can do so easily. Or if I want to change the default value moving forward, I only have one place to update it.

The following code creates the function and a table using it for the default DateTime value. Then inserts and select from the table without specifying the value for Modified. Then cleans up after itself. I hope this helps.

-- CREATE FUNCTION
CREATE FUNCTION dbo.DateTime_MinValue ( )
RETURNS DATETIME
AS 
    BEGIN
        DECLARE @dateTime_min DATETIME ;
        SET @dateTime_min = '1/1/1753 12:00:00 AM'
        RETURN @dateTime_min ;
    END ;
GO


-- CREATE TABLE USING FUNCTION FOR DEFAULT
CREATE TABLE TestTable
(
  TestTableId INT IDENTITY(1, 1)
                  PRIMARY KEY CLUSTERED ,
  Value VARCHAR(50) ,
  Modified DATETIME DEFAULT dbo.DateTime_MinValue()
) ;


-- INSERT VALUE INTO TABLE
INSERT  INTO TestTable
        ( Value )
VALUES  ( 'Value' ) ;


-- SELECT FROM TABLE
SELECT  TestTableId ,
        VALUE ,
        Modified
FROM    TestTable ;


-- CLEANUP YOUR DB
DROP TABLE TestTable ;
DROP FUNCTION dbo.DateTime_MinValue ;

support FragmentPagerAdapter holds reference to old fragments

You can remove the fragments when destroy the viewpager, in my case, I removed them on onDestroyView() of my fragment:

@Override
public void onDestroyView() {

    if (getChildFragmentManager().getFragments() != null) {
        for (Fragment fragment : getChildFragmentManager().getFragments()) {
            getChildFragmentManager().beginTransaction().remove(fragment).commitAllowingStateLoss();
        }
    }

    super.onDestroyView();
}

This API project is not authorized to use this API. Please ensure that this API is activated in the APIs Console

Here are the steps that worked for me:

  1. Enable Directions API; Geocoding API; Gelocation API console.cloud.google.com/google/maps-apis
  2. Enable APIS and Services to select APIs console.developers.google.com/apis/library

jQuery delete all table rows except first

Consider a table with id tbl: the jQuery code would be:

$('#tbl tr:not(:first)').remove();

How to redirect a page using onclick event in php?

you are using onclick which is javascript event. there is two ways

Javascript

<input type="button" value="Home" class="homebutton" id="btnHome" 
onClick="window.location = 'http://google.com'" />

Or PHP

create another page as redirect.php and put

<?php header('location : google.com') ?>

and insert this link on any page within the same directory

<a href="redirect.php">google<a/>

hope this helps its simplest!!

Visual C++: How to disable specific linker warnings?

The PDB file is typically used to store debug information. This warning is caused probably because the file vc80.pdb is not found when linking the target object file. Read the MSDN entry on LNK4099 here.

Alternatively, you can turn off debug information generation from the Project Properties > Linker > Debugging > Generate Debug Info field.

Event detect when css property changed using Jquery

For properties for which css transition will affect, can use transitionend event, example for z-index:

_x000D_
_x000D_
$(".observed-element").on("webkitTransitionEnd transitionend", function(e) {_x000D_
  console.log("end", e);_x000D_
  alert("z-index changed");_x000D_
});_x000D_
_x000D_
$(".changeButton").on("click", function() {_x000D_
  console.log("click");_x000D_
  document.querySelector(".observed-element").style.zIndex = (Math.random() * 1000) | 0;_x000D_
});
_x000D_
.observed-element {_x000D_
  transition: z-index 1ms;_x000D_
  -webkit-transition: z-index 1ms;_x000D_
}_x000D_
div {_x000D_
  width: 100px;_x000D_
  height: 100px;_x000D_
  border: 1px solid;_x000D_
  position: absolute;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<button class="changeButton">change z-index</button>_x000D_
<div class="observed-element"></div>
_x000D_
_x000D_
_x000D_

How to extend a class in python?

class MyParent:

    def sayHi():
        print('Mamma says hi')
from path.to.MyParent import MyParent

class ChildClass(MyParent):
    pass

An instance of ChildClass will then inherit the sayHi() method.

Python DNS module import error

On Debian 7 Wheezy, I had to do:

pip install --upgrade dnspython

even if python-dns package was installed.

Bootstrap 3 grid with no gap

I always add this style to my Bootstrap LESS / SASS:

.row-no-padding {
  [class*="col-"] {
    padding-left: 0 !important;
    padding-right: 0 !important;
  }
}

Then in the HTML you can write:

<div class="row row-no-padding">

How do disable paging by swiping with finger in ViewPager but still be able to swipe programmatically?

To disable swipe

mViewPager.beginFakeDrag();

To enable swipe

mViewPager.endFakeDrag();

WPF Image Dynamically changing Image source during runtime

Me.imgAddNew.Source = New System.Windows.Media.Imaging.BitmapImage(New Uri("/SPMS;component/Images/Cancel__Red-64.png", UriKind.Relative))

Add default value of datetime field in SQL Server to a timestamp

Disallow Nulls on the column and set a default on the column of getdate()

/*Deal with any existing NULLs*/
UPDATE YourTable SET created_date=GETDATE() /*Or some sentinel value 
                                                '19000101' maybe?*/
WHERE created_date IS NULL


/*Disallow NULLs*/
ALTER TABLE YourTable ALTER COLUMN created_date DATE NOT NULL

/*Add default constraint*/
ALTER TABLE YourTable ADD CONSTRAINT
    DF_YourTable_created_date DEFAULT GETDATE() FOR created_date

dlib installation on Windows 10

Follow these steps:

  • pip install cmake
  • Install Visual Studio build tools from here.
  • In Visual Studio 2017 go to the Individual Components tab, Visual C++ Tools for Cmake, and check the checkbox under the "Compilers, build tools and runtimes" section.
  • pip install dlib

How to convert JSON to XML or XML to JSON?

I'm not sure there is point in such conversion (yes, many do it, but mostly to force a square peg through round hole) -- there is structural impedance mismatch, and conversion is lossy. So I would recommend against such format-to-format transformations.

But if you do it, first convert from json to object, then from object to xml (and vice versa for reverse direction). Doing direct transformation leads to ugly output, loss of information, or possibly both.

How to remove last n characters from a string in Bash?

I tried the following and it worked for me:

#! /bin/bash

var="hello.c"
length=${#var}
endindex=$(expr $length - 4)
echo ${var:0:$endindex}

Output: hel

Warning: implode() [function.implode]: Invalid arguments passed

function my_get_tags_sitemap(){
    if ( !function_exists('wp_tag_cloud') || get_option('cb2_noposttags')) return;
    $unlinkTags = get_option('cb2_unlinkTags'); 
    echo '<div class="tags"><h2>Tags</h2>';
    $ret = []; // here you need to add array which you call inside implode function
    if($unlinkTags)
    {
        $tags = get_tags();
        foreach ($tags as $tag){
            $ret[]= $tag->name;
        }
        //ERROR OCCURS HERE
        echo implode(', ', $ret);
    }
    else
    {
        wp_tag_cloud('separator=, &smallest=11&largest=11');
    }
    echo '</div>';
}

How to compress image size?

Use Compressor (Image compression library). Visit zetbaitsu/Compressor for code and documentation.

  1. add dependency in gradle (app level)

    dependencies {
        implementation 'id.zelory:compressor:3.0.0'
    }
    
  2. To Compress Image use one of these approaches:

  • Compress Image File:

          val compressedImageFile = Compressor.compress(context, actualImageFile)
    
  • Compress Image File to Bitmap:

          val compressedImageFile = Compressor.compress(context, actualImageFile)
          val bitmap = BitmapFactory.decodeFile(compressedImageFile.path)
    

Check if a String is in an ArrayList of Strings

    List list1 = new ArrayList();
    list1.add("one");
    list1.add("three");
    list1.add("four");

    List list2 = new ArrayList();
    list2.add("one");
    list2.add("two");
    list2.add("three");
    list2.add("four");
    list2.add("five");


    list2.stream().filter( x -> !list1.contains(x) ).forEach(x -> System.out.println(x));

The output is:

two
five

Why is Java Vector (and Stack) class considered obsolete or deprecated?

You can use the synchronizedCollection/List method in java.util.Collection to get a thread-safe collection from a non-thread-safe one.

Remove the last character in a string in T-SQL?

I can suggest this -hack- ;).

select 
    left(txt, abs(len(txt + ',') - 2))
from 
    t;

SQL Server Fiddle Demo

Change x axes scale in matplotlib

Try using matplotlib.pyplot.ticklabel_format:

import matplotlib.pyplot as plt
...
plt.ticklabel_format(style='sci', axis='x', scilimits=(0,0))

This applies scientific notation (i.e. a x 10^b) to your x-axis tickmarks

Inserting HTML into a div

As alternative you can use insertAdjacentHTML - however I dig into and make some performance tests - (2019.09.13 Friday) MacOs High Sierra 10.13.6 on Chrome 76.0.3809 (64-bit), Safari 12.1.2 (13604.5.6), Firefox 69.0.0 (64-bit) ). The test F is only for reference - it is out of the question scope because we need to insert dynamically html - but in F I do it by 'hand' (in static way) - theoretically (as far I know) this should be the fastest way to insert new html elements.

enter image description here

SUMMARY

  • The A innerHTML = (do not confuse with +=) is fastest (Safari 48k operations per second, Firefox 43k op/sec, Chrome 23k op/sec) The A is ~31% slower than ideal solution F only chrome but on safari and firefox is faster (!)
  • The B innerHTML +=... is slowest on all browsers (Chrome 95 op/sec, Firefox 88 op/sec, Sfari 84 op/sec)
  • The D jQuery is second slow on all browsers (Safari 14 op/sec, Firefox 11k op/sec, Chrome 7k op/sec)
  • The reference solution F (theoretically fastest) is not fastest on firefox and safari (!!!) - which is surprising
  • The fastest browser was Safari

More info about why innerHTML = is much faster than innerHTML += is here. You can perform test on your machine/browser HERE

_x000D_
_x000D_
let html = "<div class='box'>Hello <span class='msg'>World</span> !!!</div>"_x000D_
_x000D_
function A() {    _x000D_
  container.innerHTML = `<div id="A_oiio">A: ${html}</div>`;_x000D_
}_x000D_
_x000D_
function B() {    _x000D_
  container.innerHTML += `<div id="B_oiio">B: ${html}</div>`;_x000D_
}_x000D_
_x000D_
function C() {    _x000D_
  container.insertAdjacentHTML('beforeend', `<div id="C_oiio">C: ${html}</div>`);_x000D_
}_x000D_
_x000D_
function D() {    _x000D_
  $('#container').append(`<div id="D_oiio">D: ${html}</div>`);_x000D_
}_x000D_
_x000D_
function E() {_x000D_
  let d = document.createElement("div");_x000D_
  d.innerHTML = `E: ${html}`;_x000D_
  d.id = 'E_oiio';_x000D_
  container.appendChild(d);_x000D_
}_x000D_
_x000D_
function F() {    _x000D_
  let dm = document.createElement("div");_x000D_
  dm.id = "F_oiio";_x000D_
  dm.appendChild(document.createTextNode("F: "));_x000D_
_x000D_
  let d = document.createElement("div");_x000D_
  d.classList.add('box');_x000D_
  d.appendChild(document.createTextNode("Hello "));_x000D_
  _x000D_
  let s = document.createElement("span");_x000D_
  s.classList.add('msg');_x000D_
  s.appendChild(document.createTextNode("World"));_x000D_
_x000D_
  d.appendChild(s);_x000D_
  d.appendChild(document.createTextNode(" !!!"));_x000D_
  dm.appendChild( d );_x000D_
  _x000D_
  container.appendChild(dm);_x000D_
}_x000D_
_x000D_
_x000D_
A();_x000D_
B();_x000D_
C();_x000D_
D();_x000D_
E();_x000D_
F();
_x000D_
.warr { color: red } .msg { color: blue } .box {display: inline}
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
_x000D_
<div class="warr">This snippet only for show code used in test (in jsperf.com) - it not perform test itself. </div>_x000D_
<div id="container"></div>
_x000D_
_x000D_
_x000D_

How to Empty Caches and Clean All Targets Xcode 4 and later

I have been pulling out hair from my head because I thought that I had the same problem. When building the app I didn't get the same result on my iPhone as on the simulator.

The problem was that I had somehow made a localized version of the MainStoryboard.storyboard file. So when I ran the app on my phone it showed the danish version... and the simulator showed the english version.

Yeah I'm new! :)

How can I check whether a variable is defined in Node.js?

Determine if property is existing (but is not a falsy value):

if (typeof query !== 'undefined' && query !== null){
   doStuff();
}

Usually using

if (query){
   doStuff();
}

is sufficient. Please note that:

if (!query){
   doStuff();
}

doStuff() will execute even if query was an existing variable with falsy value (0, false, undefined or null)

Btw, there's a sexy coffeescript way of doing this:

if object?.property? then doStuff()

which compiles to:

if ((typeof object !== "undefined" && object !== null ? object.property : void 0) != null) 

{
  doStuff();
}

Sending arrays with Intent.putExtra

This code sends array of integer values

Initialize array List

List<Integer> test = new ArrayList<Integer>();

Add values to array List

test.add(1);
test.add(2);
test.add(3);
Intent intent=new Intent(this, targetActivty.class);

Send the array list values to target activity

intent.putIntegerArrayListExtra("test", (ArrayList<Integer>) test);
startActivity(intent);

here you get values on targetActivty

Intent intent=getIntent();
ArrayList<String> test = intent.getStringArrayListExtra("test");

What does \0 stand for?

In C, \0 denotes a character with value zero. The following are identical:

char a = 0;
char b = '\0';

The utility of this escape sequence is greater inside string literals, which are arrays of characters:

char arr[] = "abc\0def\0ghi\0";

(Note that this array has two zero characters at the end, since string literals include a hidden, implicit terminal zero.)

Is it possible to sort a ES6 map object?

You can convert to an array and call array soring methods on it:

[...map].sort(/* etc */);

Bootstrap 4 - Inline List?

Inline

_x000D_
_x000D_
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" >
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>


<ul class="list-inline">
  <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">FB</a></li>
  <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">G+</a></li>
  <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">T</a></li>
</ul>
_x000D_
_x000D_
_x000D_

and learn more about https://getbootstrap.com/docs/4.0/content/typography/#inline

Bootstrap 4 responsive tables won't take up 100% width

That's because the .table-responsive class adds the property display: block to your element which changes it from the previous display: table.

Override this property back to display: table in your own stylesheet

.table-responsive {
    display: table;
}

Note: make sure this style executes after your bootstrap code for it to override.

How can I find the number of days between two Date objects in Ruby?

Subtract the beginning date from the end date:

endDate - beginDate 

windows batch file rename

I rename in code

echo off

setlocal EnableDelayedExpansion

for %%a in (*.txt) do (
    REM echo %%a
    set x=%%a
    set mes=!x:~17,3!

    if !mes!==JAN (
        set mes=01
    )

    if !mes!==ENE (
        set mes=01
    )

    if !mes!==FEB (
        set mes=02
    )

    if !mes!==MAR (
        set mes=03
    )

    if !mes!==APR (
        set mes=04
    )

    if !mes!==MAY (
        set mes=05
    )

    if !mes!==JUN (
        set mes=06
    )

    if !mes!==JUL (
        set mes=07
    )

    if !mes!==AUG (
        set mes=08
    )

    if !mes!==SEP (
        set mes=09
    )

    if !mes!==OCT (
        set mes=10
    )

    if !mes!==NOV (
        set mes=11
    )

    if !mes!==DEC (
        set mes=12
    )

    ren %%a !x:~20,4!!mes!!x:~15,2!.txt 

    echo !x:~20,4!!mes!!x:~15,2!.txt 

)

Convert file: Uri to File in Android

For folks that are here looking for a solution for images in particular here it is.

private Bitmap getBitmapFromUri(Uri contentUri) {
        String path = null;
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = getContentResolver().query(contentUri, projection, null, null, null);
        if (cursor.moveToFirst()) {
            int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
            path = cursor.getString(columnIndex);
        }
        cursor.close();
        Bitmap bitmap = BitmapFactory.decodeFile(path);
        return bitmap;
    }

JavaScript to get rows count of a HTML table

This is another option, using jQuery and getting only tbody rows (with the data) and desconsidering thead/tfoot.

$("#tableId > tbody > tr").length

_x000D_
_x000D_
console.log($("#myTableId > tbody > tr").length);
_x000D_
.demo {
   width:100%;
   height:100%;
   border:1px solid #C0C0C0;
   border-collapse:collapse;
   border-spacing:2px;
   padding:5px;
}

.demo caption {
   caption-side:top;
   text-align:center;
}

.demo th {
   border:1px solid #C0C0C0;
   padding:5px;
   background:#F0F0F0;
}

.demo td {
   border:1px solid #C0C0C0;
   text-align:left;
   padding:5px;
   background:#FFFFFF;
}
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table id="myTableId" class="demo">
   <caption>Table 1</caption>
   <thead>
      <tr>
         <th>Header 1</th>
         <th>Header 2</th>
         <th>Header 3</th>
         <th>Header 4</th>
      </tr>
   </thead>
   <tbody>
      <tr>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
      </tr>
      <tr>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
      </tr>
      <tr>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
      </tr>
      <tr>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
         <td>&nbsp;</td>
      </tr>
   </tbody>
   <tfoot>
      <tr>
         <td colspan=4 style="background:#F0F0F0">&nbsp; </td>
      </tr>
   </tfoot>
</table>
_x000D_
_x000D_
_x000D_