Programs & Examples On #Xmp

The Adobe Extensible Metadata Platform (XMP) is a standard, created by Adobe Systems Inc., for processing and storing standardized and proprietary information relating to the contents of a file.

Getting Image from API in Angular 4/5+?

angular 5 :

 getImage(id: string): Observable<Blob> {
    return this.httpClient.get('http://myip/image/'+id, {responseType: "blob"});

How to programmatically set the SSLContext of a JAX-WS client?

I tried the following and it didn't work on my environment:

bindingProvider.getRequestContext().put("", getCustomSocketFactory());

But different property worked like a charm:

bindingProvider.getRequestContext().put(JAXWSProperties.SSL_SOCKET_FACTORY, getCustomSocketFactory());

The rest of the code was taken from the first reply.

How to convert a .eps file to a high quality 1024x1024 .jpg?

For vector graphics, ImageMagick has both a render resolution and an output size that are independent of each other.

Try something like

convert -density 300 image.eps -resize 1024x1024 image.jpg

Which will render your eps at 300dpi. If 300 * width > 1024, then it will be sharp. If you render it too high though, you waste a lot of memory drawing a really high-res graphic only to down sample it again. I don't currently know of a good way to render it at the "right" resolution in one IM command.

The order of the arguments matters! The -density X argument needs to go before image.eps because you want to affect the resolution that the input file is rendered at.

This is not super obvious in the manpage for convert, but is hinted at:


convert [input-option] input-file [output-option] output-file

Position absolute and overflow hidden

What about position: relative for the outer div? In the example that hides the inner one. It also won't move it in its layout since you don't specify a top or left.

Which port(s) does XMPP use?

The ports required will be different for your XMPP Server and any XMPP Clients. Most "modern" XMPP Servers follow the defined IANA Ports for Server-to-Server 5269 and for Client-to-Server 5222. Any additional ports depends on what features you enable on the Server, i.e. if you offer BOSH then you may need to open port 80.

File Transfer is highly dependent on both the Clients you use and the Server as to what port it will use, but most of them also negotiate the connect via your existing XMPP Client-to-Server link so the required port opening will be client side (or proxied via port 80.)

How to Load RSA Private Key From File

Two things. First, you must base64 decode the mykey.pem file yourself. Second, the openssl private key format is specified in PKCS#1 as the RSAPrivateKey ASN.1 structure. It is not compatible with java's PKCS8EncodedKeySpec, which is based on the SubjectPublicKeyInfo ASN.1 structure. If you are willing to use the bouncycastle library you can use a few classes in the bouncycastle provider and bouncycastle PKIX libraries to make quick work of this.


import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;

// ...   

String keyPath = "mykey.pem";
BufferedReader br = new BufferedReader(new FileReader(keyPath));
Security.addProvider(new BouncyCastleProvider());
PEMParser pp = new PEMParser(br);
PEMKeyPair pemKeyPair = (PEMKeyPair) pp.readObject();
KeyPair kp = new JcaPEMKeyConverter().getKeyPair(pemKeyPair);
samlResponse.sign(Signature.getInstance("SHA1withRSA").toString(), kp.getPrivate(), certs);

Is there a WebSocket client implemented for Python?

Since I have been doing a bit of research in that field lately (Jan, '12), the most promising client is actually : WebSocket for Python. It support a normal socket that you can call like this :

ws = EchoClient('http://localhost:9000/ws')

The client can be Threaded or based on IOLoop from Tornado project. This will allow you to create a multi concurrent connection client. Useful if you want to run stress tests.

The client also exposes the onmessage, opened and closed methods. (WebSocket style).

What is the ellipsis (...) for in this method signature?

The three dot (...) notation is actually borrowed from mathematics, and it means "...and so on".

As for its use in Java, it stands for varargs, meaning that any number of arguments can be added to the method call. The only limitations are that the varargs must be at the end of the method signature and there can only be one per method.

Using a SELECT statement within a WHERE clause

The principle of subqueries is not at all bad, but I don't think that you should use it in your example. If I understand correctly you want to get the maximum score for each date. In this case you should use a GROUP BY.

What is the meaning of polyfills in HTML5?

First off let's clarify what a polyfil is not: A polyfill is not part of the HTML5 Standard. Nor is a polyfill limited to Javascript, even though you often see polyfills being referred to in those contexts.

The term polyfill itself refers to some code that "allows you to have some specific functionality that you expect in current or “modern” browsers to also work in other browsers that do not have the support for that functionality built in. "

Source and example of polyfill here:

What's the most efficient way to test two integer ranges for overlap?

This can easily warp a normal human brain, so I've found a visual approach to be easier to understand:

overlap madness

le Explanation

If two ranges are "too fat" to fit in a slot that is exactly the sum of the width of both, then they overlap.

For ranges [a1, a2] and [b1, b2] this would be:

 * we are testing for:
 *     max point - min point < w1 + w2    
if max(a2, b2) - min(a1, b1) < (a2 - a1) + (b2 - b1) {
  // too fat -- they overlap!

Iterating through a range of dates in Python

Use the dateutil library:

from datetime import date
from dateutil.rrule import rrule, DAILY

a = date(2009, 5, 30)
b = date(2009, 6, 9)

for dt in rrule(DAILY, dtstart=a, until=b):
    print dt.strftime("%Y-%m-%d")

This python library has many more advanced features, some very useful, like relative deltas—and is implemented as a single file (module) that's easily included into a project.

Is it possible to see more than 65536 rows in Excel 2007?

According to this MSDN entry, the limit is 1 million rows. You could be running in compatibility mode, which would limit you to the old standard of 65k. Does your excel say compatibility mode in the title? If so, you can save the file as a new style file under the "save as" menu, or change your default to always use the 2007 file standard.

PHP display image BLOB from MySQL

Since I have to store various types of content in my blob field/column, I am suppose to update my code like this:

echo "data: $mime" $result['$data']";

where: mime can be an image of any kind, text, word document, text document, PDF document, etc... content datatype is blob in database.

How to fetch FetchType.LAZY associations with JPA and Hibernate in a Spring Controller

it can only be lazily loaded whilst within a transaction. So you could access the collection in your repository, which has a transaction - or what I normally do is a get with association, or set fetchmode to eager.

Windows.history.back() + location.reload() jquery

You can't do window.history.back(); and location.reload(); in the same function.

window.history.back() breaks the javascript flow and redirects to previous page, location.reload() is never processed.

location.reload() has to be called on the page you redirect to when using window.history.back().

I would used an url to redirect instead of history.back, that gives you both a redirect and refresh.

SSIS Excel Connection Manager failed to Connect to the Source

Simple workaround is to open the file and simply press save button in Excel (no need to change the format). once saved in excel it will start to work and you should be able to see its sheets in the DFT.

(How) can I count the items in an enum?

Add a entry, at the end of your enum, called Folders_MAX or something similar and use this value when initializing your arrays.

ContainerClass* m_containers[Folders_MAX];

Return multiple values from a function, sub or type?

A function returns one value, but it can "output" any number of values. A sample code:

Function Test (ByVal Input1 As Integer, ByVal Input2 As Integer, _
ByRef Output1 As Integer, ByRef Output2 As Integer) As Integer

  Output1 = Input1 + Input2
  Output2 = Input1 - Input2
  Test = Output1 + Output2

End Function

Sub Test2()

  Dim Ret As Integer, Input1 As Integer, Input2 As Integer, _
  Output1 As integer, Output2 As Integer
  Input1 = 1
  Input2 = 2
  Ret = Test(Input1, Input2, Output1, Output2)
  Sheet1.Range("A1") = Ret     ' 2
  Sheet1.Range("A2") = Output1 ' 3
  Sheet1.Range("A3") = Output2 '-1

End Sub

Displaying the build date

For anyone that needs to get the compile time in Windows 8 / Windows Phone 8:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestamp(Assembly assembly)
        var pkg = Windows.ApplicationModel.Package.Current;
        if (null == pkg)
            return null;

        var assemblyFile = await pkg.InstalledLocation.GetFileAsync(assembly.ManifestModule.Name);
        if (null == assemblyFile)
            return null;

        using (var stream = await assemblyFile.OpenSequentialReadAsync())
            using (var reader = new DataReader(stream))
                const int PeHeaderOffset = 60;
                const int LinkerTimestampOffset = 8;

                //read first 2048 bytes from the assembly file.
                byte[] b = new byte[2048];
                await reader.LoadAsync((uint)b.Length);

                //get the pe header offset
                int i = System.BitConverter.ToInt32(b, PeHeaderOffset);

                //read the linker timestamp from the PE header
                int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);

                var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
                return dt.AddSeconds(secondsSince1970);

For anyone that needs to get the compile time in Windows Phone 7:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestampAsync(Assembly assembly)
        const int PeHeaderOffset = 60;
        const int LinkerTimestampOffset = 8;            
        byte[] b = new byte[2048];

            var rs = Application.GetResourceStream(new Uri(assembly.ManifestModule.Name, UriKind.Relative));
            using (var s = rs.Stream)
                var asyncResult = s.BeginRead(b, 0, b.Length, null, null);
                int bytesRead = await Task.Factory.FromAsync<int>(asyncResult, s.EndRead);
        catch (System.IO.IOException)
            return null;

        int i = System.BitConverter.ToInt32(b, PeHeaderOffset);
        int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);
        var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
        dt = dt.AddSeconds(secondsSince1970);
        return dt;

NOTE: In all cases you're running in a sandbox, so you'll only be able to get the compile time of assemblies that you deploy with your app. (i.e. this won't work on anything in the GAC).

Restoring Nuget References?

I suffered from this issue too a lot, in my case Downloading missing NuGet was checked (but it is not restoring them) and i can not uninstall & re-install because i modified some of the installed packages ... so:

I just cleared the cached and rebuild and it worked. (Tools-Option-Nuget Package Manager - General)

also this link helps

How can I create a blank/hardcoded column in a sql query?

    0 as placeholder

And '' as placeholder for strings.

Difference between JSON.stringify and JSON.parse

They are the inverse of each other. JSON.stringify() serializes a JS object into a JSON string, whereas JSON.parse() will deserialize a JSON string into a JS object.

How to count frequency of characters in a string?

You can use a java Map and map a char to an int. You can then iterate over the characters in the string and check if they have been added to the map, if they have, you can then increment its value.

For example:

HashMap<Character, Integer> map = new HashMap<Character, Integer>();
String s = "aasjjikkk";
for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
    Integer val = map.get(c);
    if (val != null) {
        map.put(c, new Integer(val + 1));
    else {
       map.put(c, 1);

At the end you will have a count of all the characters you encountered and you can extract their frequencies from that.

Alternatively, you can use Bozho's solution of using a Multiset and counting the total occurences.

dplyr mutate with conditional values

It looks like derivedFactor from the mosaic package was designed for this. In this example, it would look something like:

myfile <- mutate(myfile, V5 = derivedFactor(
    "1" = (V1==1 & V2!=4),
    "2" = (V2==4 & V3!=1),
    .method = "first",
    .default = 0

(If you want the outcome to be numeric instead of a factor, wrap the derivedFactor with an as.numeric.)

Note that the .default option combined with .method = "first" sets the "else" condition -- this approach is described in the help file for derivedFactor.

How can I select an element by name with jQuery?

Any attribute can be selected using [attribute_name=value] way. See the sample here:

var value = $("[name='nameofobject']");

How to get public directory?

Use public_path()

For reference:

// Path to the project's root folder    
echo base_path();

// Path to the 'app' folder    
echo app_path();        

// Path to the 'public' folder    
echo public_path();

// Path to the 'storage' folder    
echo storage_path();

// Path to the 'storage/app' folder    
echo storage_path('app');

How to install grunt and how to build script with it

Some time we need to set PATH variable for WINDOWS


After that test with where grunt

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

Using an HTTP PROXY - Python

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

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

ES6 class variable alternatives

You can mimic es6 classes behaviour... and use your class variables :)

Look mum... no classes!

// Helper
const $constructor = Symbol();
const $extends = (parent, child) =>
  Object.assign(Object.create(parent), child);
const $new = (object, ...args) => {
  let instance = Object.create(object);
  instance[$constructor].call(instance, ...args);
  return instance;
const $super = (parent, context, ...args) => {
  parent[$constructor].call(context, ...args)
// class
var Foo = {
  classVariable: true,

  // constructor
  [$constructor](who){ = who;
    this.species = 'fufel';

  // methods
    return 'I am ' +;

// class extends Foo
var Bar = $extends(Foo, {

  // constructor
    $super(Foo, this, who);
    this.subtype = 'barashek';

  // methods
    console.log('Hello, ' + this.identify());

var a1 = $new(Foo, 'a1');
var b1 = $new(Bar, 'b1');
console.log(a1, b1);
console.log('b1.classVariable', b1.classVariable);

I put it on GitHub

Else clause on Python while statement

The better use of 'while: else:' construction in Python should be if no loop is executed in 'while' then the 'else' statement is executed. The way it works today doesn't make sense because you can use the code below with the same results...

n = 5
while n != 0:
    print n
    n -= 1
print "what the..."

No space left on device

Such difference between the output of du -sh and df -h may happen if some large file has been deleted, but is still opened by some process. Check with the command lsof | grep deleted to see which processes have opened descriptors to deleted files. You can restart the process and the space will be freed.

How to get jQuery to wait until an effect is finished?

You can as well use $.when() to wait until the promise finished:

var myEvent = function() {
    $( selector ).fadeOut( 'fast' );
$.when( myEvent() ).done( function() {
    console.log( 'Task finished.' );
} );

In case you're doing a request that could as well fail, then you can even go one step further:

$.when( myEvent() )
    .done( function( d ) {
        console.log( d, 'Task done.' );
    } )
    .fail( function( err ) {
        console.log( err, 'Task failed.' );
    } )
    // Runs always
    .then( function( data, textStatus, jqXHR ) {
        console.log( jqXHR.status, textStatus, 'Status 200/"OK"?' );
    } );

How to convert number to words in java

In this post i have just update Yanick Rochon's code. I have make it workable with lower version of java 1.6 and i was getting the output for 1.00 = one and  hundredth. So i have update the code. New i get the output for 1.00 = one and zero hundredth.

I don't not what should i do. Add a new answer or edit that post. As the answer is highly ranked so i have made a new post with updating the code. I have just change this two things have mention above.

 * This class will convert numeric values into an english representation
 * For units, see :
 * @author [email protected]
public class NumberToWords {

    static public class ScaleUnit {
        private int exponent;
        private String[] names;

        private ScaleUnit(int exponent, String... names) {
            this.exponent = exponent;
            this.names = names;

        public int getExponent() {
            return exponent;

        public String getName(int index) {
            return names[index];

     * See
    static private ScaleUnit[] SCALE_UNITS = new ScaleUnit[] {
            new ScaleUnit(63, "vigintillion", "decilliard"),
            new ScaleUnit(60, "novemdecillion", "decillion"),
            new ScaleUnit(57, "octodecillion", "nonilliard"),
            new ScaleUnit(54, "septendecillion", "nonillion"),
            new ScaleUnit(51, "sexdecillion", "octilliard"),
            new ScaleUnit(48, "quindecillion", "octillion"),
            new ScaleUnit(45, "quattuordecillion", "septilliard"),
            new ScaleUnit(42, "tredecillion", "septillion"),
            new ScaleUnit(39, "duodecillion", "sextilliard"),
            new ScaleUnit(36, "undecillion", "sextillion"),
            new ScaleUnit(33, "decillion", "quintilliard"),
            new ScaleUnit(30, "nonillion", "quintillion"),
            new ScaleUnit(27, "octillion", "quadrilliard"),
            new ScaleUnit(24, "septillion", "quadrillion"),
            new ScaleUnit(21, "sextillion", "trilliard"),
            new ScaleUnit(18, "quintillion", "trillion"),
            new ScaleUnit(15, "quadrillion", "billiard"),
            new ScaleUnit(12, "trillion", "billion"),
            new ScaleUnit(9, "billion", "milliard"),
            new ScaleUnit(6, "million", "million"),
            new ScaleUnit(3, "thousand", "thousand"),
            new ScaleUnit(2, "hundred", "hundred"),
            // new ScaleUnit(1, "ten", "ten"),
            // new ScaleUnit(0, "one", "one"),
            new ScaleUnit(-1, "tenth", "tenth"), new ScaleUnit(-2, "hundredth", "hundredth"),
            new ScaleUnit(-3, "thousandth", "thousandth"),
            new ScaleUnit(-4, "ten-thousandth", "ten-thousandth"),
            new ScaleUnit(-5, "hundred-thousandth", "hundred-thousandth"),
            new ScaleUnit(-6, "millionth", "millionth"),
            new ScaleUnit(-7, "ten-millionth", "ten-millionth"),
            new ScaleUnit(-8, "hundred-millionth", "hundred-millionth"),
            new ScaleUnit(-9, "billionth", "milliardth"),
            new ScaleUnit(-10, "ten-billionth", "ten-milliardth"),
            new ScaleUnit(-11, "hundred-billionth", "hundred-milliardth"),
            new ScaleUnit(-12, "trillionth", "billionth"),
            new ScaleUnit(-13, "ten-trillionth", "ten-billionth"),
            new ScaleUnit(-14, "hundred-trillionth", "hundred-billionth"),
            new ScaleUnit(-15, "quadrillionth", "billiardth"),
            new ScaleUnit(-16, "ten-quadrillionth", "ten-billiardth"),
            new ScaleUnit(-17, "hundred-quadrillionth", "hundred-billiardth"),
            new ScaleUnit(-18, "quintillionth", "trillionth"),
            new ScaleUnit(-19, "ten-quintillionth", "ten-trillionth"),
            new ScaleUnit(-20, "hundred-quintillionth", "hundred-trillionth"),
            new ScaleUnit(-21, "sextillionth", "trilliardth"),
            new ScaleUnit(-22, "ten-sextillionth", "ten-trilliardth"),
            new ScaleUnit(-23, "hundred-sextillionth", "hundred-trilliardth"),
            new ScaleUnit(-24, "septillionth", "quadrillionth"),
            new ScaleUnit(-25, "ten-septillionth", "ten-quadrillionth"),
            new ScaleUnit(-26, "hundred-septillionth", "hundred-quadrillionth"), };

    static public enum Scale {
        SHORT, LONG;

        public String getName(int exponent) {
            for (ScaleUnit unit : SCALE_UNITS) {
                if (unit.getExponent() == exponent) {
                    return unit.getName(this.ordinal());
            return "";

     * Change this scale to support American and modern British value (short scale) or Traditional
     * British value (long scale)
    static public Scale SCALE = Scale.SHORT;

    static abstract public class AbstractProcessor {

        static protected final String SEPARATOR = " ";
        static protected final int NO_VALUE = -1;

        protected List<Integer> getDigits(long value) {
            ArrayList<Integer> digits = new ArrayList<Integer>();
            if (value == 0) {
            } else {
                while (value > 0) {
                    digits.add(0, (int) value % 10);
                    value /= 10;
            return digits;

        public String getName(long value) {
            return getName(Long.toString(value));

        public String getName(double value) {
            return getName(Double.toString(value));

        abstract public String getName(String value);

    static public class UnitProcessor extends AbstractProcessor {

        static private final String[] TOKENS = new String[] { "one", "two", "three", "four",
                "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen",
                "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };

        public String getName(String value) {
            StringBuilder buffer = new StringBuilder();

            int offset = NO_VALUE;
            int number;
            if (value.length() > 3) {
                number = Integer.valueOf(value.substring(value.length() - 3), 10);
            } else {
                number = Integer.valueOf(value, 10);
            number %= 100;
            if (number < 10) {
                offset = (number % 10) - 1;
                // number /= 10;
            } else if (number < 20) {
                offset = (number % 20) - 1;
                // number /= 100;

            if (offset != NO_VALUE && offset < TOKENS.length) {

            return buffer.toString();


    static public class TensProcessor extends AbstractProcessor {

        static private final String[] TOKENS = new String[] { "twenty", "thirty", "fourty",
                "fifty", "sixty", "seventy", "eighty", "ninety" };

        static private final String UNION_SEPARATOR = "-";

        private UnitProcessor unitProcessor = new UnitProcessor();

        public String getName(String value) {
            StringBuilder buffer = new StringBuilder();
            boolean tensFound = false;

            int number;
            if (value.length() > 3) {
                number = Integer.valueOf(value.substring(value.length() - 3), 10);
            } else {
                number = Integer.valueOf(value, 10);
            number %= 100; // keep only two digits
            if (number >= 20) {
                buffer.append(TOKENS[(number / 10) - 2]);
                number %= 10;
                tensFound = true;
            } else {
                number %= 20;

            if (number != 0) {
                if (tensFound) {

            return buffer.toString();

    static public class HundredProcessor extends AbstractProcessor {

        private int EXPONENT = 2;

        private UnitProcessor unitProcessor = new UnitProcessor();
        private TensProcessor tensProcessor = new TensProcessor();

        public String getName(String value) {
            StringBuilder buffer = new StringBuilder();

            int number;
            if ("".equals(value)) {
                number = 0;
            } else if (value.length() > 4) {
                number = Integer.valueOf(value.substring(value.length() - 4), 10);
            } else {
                number = Integer.valueOf(value, 10);
            number %= 1000; // keep at least three digits

            if (number >= 100) {
                buffer.append(unitProcessor.getName(number / 100));

            String tensName = tensProcessor.getName(number % 100);

            if (!"".equals(tensName) && (number >= 100)) {

            return buffer.toString();

    static public class CompositeBigProcessor extends AbstractProcessor {

        private HundredProcessor hundredProcessor = new HundredProcessor();
        private AbstractProcessor lowProcessor;
        private int exponent;

        public CompositeBigProcessor(int exponent) {
            if (exponent <= 3) {
                lowProcessor = hundredProcessor;
            } else {
                lowProcessor = new CompositeBigProcessor(exponent - 3);
            this.exponent = exponent;

        public String getToken() {
            return SCALE.getName(getPartDivider());

        protected AbstractProcessor getHighProcessor() {
            return hundredProcessor;

        protected AbstractProcessor getLowProcessor() {
            return lowProcessor;

        public int getPartDivider() {
            return exponent;

        public String getName(String value) {
            StringBuilder buffer = new StringBuilder();

            String high, low;
            if (value.length() < getPartDivider()) {
                high = "";
                low = value;
            } else {
                int index = value.length() - getPartDivider();
                high = value.substring(0, index);
                low = value.substring(index);

            String highName = getHighProcessor().getName(high);
            String lowName = getLowProcessor().getName(low);

            if (!"".equals(highName)) {

                if (!"".equals(lowName)) {

            if (!"".equals(lowName)) {

            return buffer.toString();

    static public class DefaultProcessor extends AbstractProcessor {

        static private String MINUS = "minus";
        static private String UNION_AND = "and";

        static private String ZERO_TOKEN = "zero";

        private AbstractProcessor processor = new CompositeBigProcessor(63);

        public String getName(String value) {
            boolean negative = false;
            if (value.startsWith("-")) {
                negative = true;
                value = value.substring(1);

            int decimals = value.indexOf(".");
            String decimalValue = null;
            if (0 <= decimals) {
                decimalValue = value.substring(decimals + 1);
                value = value.substring(0, decimals);

            String name = processor.getName(value);

            if ("".equals(name)) {
                name = ZERO_TOKEN;
            } else if (negative) {
                name = MINUS.concat(SEPARATOR).concat(name);

            if (!(null == decimalValue || "".equals(decimalValue))) {

                String zeroDecimalValue = "";
                for (int i = 0; i < decimalValue.length(); i++) {
                    zeroDecimalValue = zeroDecimalValue + "0";
                if (decimalValue.equals(zeroDecimalValue)) {
                    name = name.concat(SEPARATOR).concat(UNION_AND).concat(SEPARATOR).concat(
                } else {
                    name = name.concat(SEPARATOR).concat(UNION_AND).concat(SEPARATOR).concat(


            return name;


    static public AbstractProcessor processor;

    public static void main(String... args) {

        processor = new DefaultProcessor();

        long[] values = new long[] { 0, 4, 10, 12, 100, 108, 299, 1000, 1003, 2040, 45213, 100000,
                100005, 100010, 202020, 202022, 999999, 1000000, 1000001, 10000000, 10000007,
                99999999, Long.MAX_VALUE, Long.MIN_VALUE };

        String[] strValues = new String[] { "0", "1.30", "0001.00", "3.141592" };

        for (long val : values) {
            System.out.println(val + " = " + processor.getName(val));

        for (String strVal : strValues) {
            System.out.println(strVal + " = " + processor.getName(strVal));

        // generate a very big number...
        StringBuilder bigNumber = new StringBuilder();
        for (int d = 0; d < 66; d++) {
            bigNumber.append((char) ((Math.random() * 10) + '0'));
        for (int d = 0; d < 26; d++) {
            bigNumber.append((char) ((Math.random() * 10) + '0'));
        System.out.println(bigNumber.toString() + " = " + processor.getName(bigNumber.toString()));

The output is

0 = zero
4 = four
10 = ten
12 = twelve
100 = one hundred
108 = one hundred eight
299 = two hundred ninety-nine
1000 = one thousand
1003 = one thousand three
2040 = two thousand fourty
45213 = fourty-five thousand two hundred thirteen
100000 = one hundred thousand
100005 = one hundred thousand five
100010 = one hundred thousand ten
202020 = two hundred two thousand twenty
202022 = two hundred two thousand twenty-two
999999 = nine hundred ninety-nine thousand nine hundred ninety-nine
1000000 = one million
1000001 = one million one
10000000 = ten million
10000007 = ten million seven
99999999 = ninety-nine million nine hundred ninety-nine thousand nine hundred ninety-nine
9223372036854775807 = nine quintillion two hundred twenty-three quadrillion three hundred seventy-two trillion thirty-six billion eight hundred fifty-four million seven hundred seventy-five thousand eight hundred seven
-9223372036854775808 = minus nine quintillion two hundred twenty-three quadrillion three hundred seventy-two trillion thirty-six billion eight hundred fifty-four million seven hundred seventy-five thousand eight hundred eight
0.0 = zero and zero tenth
1.30 = one and thirty hundredth
0001.00 = one and zero hundredth
3.141592 = three and one hundred fourty-one thousand five hundred ninety-two millionth
354064188376576616844741830273568537829518115677552666352927559274.76892492652888527014418647 = three hundred fifty-four vigintillion sixty-four novemdecillion one hundred eighty-eight octodecillion three hundred seventy-six septendecillion five hundred seventy-six sexdecillion six hundred sixteen quindecillion eight hundred fourty-four quattuordecillion seven hundred fourty-one tredecillion eight hundred thirty duodecillion two hundred seventy-three undecillion five hundred sixty-eight decillion five hundred thirty-seven nonillion eight hundred twenty-nine octillion five hundred eighteen septillion one hundred fifteen sextillion six hundred seventy-seven quintillion five hundred fifty-two quadrillion six hundred sixty-six trillion three hundred fifty-two billion nine hundred twenty-seven million five hundred fifty-nine thousand two hundred seventy-four and seventy-six septillion eight hundred ninety-two sextillion four hundred ninety-two quintillion six hundred fifty-two quadrillion eight hundred eighty-eight trillion five hundred twenty-seven billion fourteen million four hundred eighteen thousand six hundred fourty-seven hundred-septillionth

Why can't I use the 'await' operator within the body of a lock statement?

Basically it would be the wrong thing to do.

There are two ways this could be implemented:

  • Keep hold of the lock, only releasing it at the end of the block.
    This is a really bad idea as you don't know how long the asynchronous operation is going to take. You should only hold locks for minimal amounts of time. It's also potentially impossible, as a thread owns a lock, not a method - and you may not even execute the rest of the asynchronous method on the same thread (depending on the task scheduler).

  • Release the lock in the await, and reacquire it when the await returns
    This violates the principle of least astonishment IMO, where the asynchronous method should behave as closely as possible like the equivalent synchronous code - unless you use Monitor.Wait in a lock block, you expect to own the lock for the duration of the block.

So basically there are two competing requirements here - you shouldn't be trying to do the first here, and if you want to take the second approach you can make the code much clearer by having two separated lock blocks separated by the await expression:

// Now it's clear where the locks will be acquired and released
lock (foo)
var result = await something;
lock (foo)

So by prohibiting you from awaiting in the lock block itself, the language is forcing you to think about what you really want to do, and making that choice clearer in the code that you write.

How to make my layout able to scroll down?

If you even did not get scroll after doing what is written above .....

Set the android:layout_height="250dp"or you can say xdp where x can be any numerical value.

Is Python strongly typed?

A Python variable stores an untyped reference to the target object that represent the value.

Any assignment operation means assigning the untyped reference to the assigned object -- i.e. the object is shared via the original and the new (counted) references.

The value type is bound to the target object, not to the reference value. The (strong) type checking is done when an operation with the value is performed (run time).

In other words, variables (technically) have no type -- it does not make sense to think in terms of a variable type if one wants to be exact. But references are automatically dereferenced and we actually think in terms of the type of the target object.

CodeIgniter : Unable to load the requested file:

"Unable to load the requested file"

Can be also caused by access permissions under linux , make sure you set the correct read permissions for the directory "views/home"

How can I dismiss the on screen keyboard?

Solution with FocusScope doesn't work for me. I found another:

import 'package:flutter/services.dart';


It solved my problem.

Converting String array to java.util.List

On Java 14 you can do this

List<String> strings = Arrays.asList("one", "two", "three");

How do you send a Firebase Notification to all devices via CURL?

I was looking solution for my Ionic Cordova app push notification.

Thanks to Syed Rafay's answer.

in app.component.ts

const options: PushOptions = {
  android: {
    topics: ['all']

in Server file

"to" => "/topics/all",

Why use Redux over Facebook Flux?

Redux author here!

Redux is not that different from Flux. Overall it has same architecture, but Redux is able to cut some complexity corners by using functional composition where Flux uses callback registration.

There is not a fundamental difference in Redux, but I find it makes certain abstractions easier, or at least possible to implement, that would be hard or impossible to implement in Flux.

Reducer Composition

Take, for example, pagination. My Flux + React Router example handles pagination, but the code for that is awful. One of the reasons it's awful is that Flux makes it unnatural to reuse functionality across stores. If two stores need to handle pagination in response to different actions, they either need to inherit from a common base store (bad! you're locking yourself into a particular design when you use inheritance), or call an externally defined function from within the event handler, which will need to somehow operate on the Flux store's private state. The whole thing is messy (although definitely in the realm of possible).

On the other hand, with Redux pagination is natural thanks to reducer composition. It's reducers all the way down, so you can write a reducer factory that generates pagination reducers and then use it in your reducer tree. The key to why it's so easy is because in Flux, stores are flat, but in Redux, reducers can be nested via functional composition, just like React components can be nested.

This pattern also enables wonderful features like no-user-code undo/redo. Can you imagine plugging Undo/Redo into a Flux app being two lines of code? Hardly. With Redux, it is—again, thanks to reducer composition pattern. I need to highlight there's nothing new about it—this is the pattern pioneered and described in detail in Elm Architecture which was itself influenced by Flux.

Server Rendering

People have been rendering on the server fine with Flux, but seeing that we have 20 Flux libraries each attempting to make server rendering “easier”, perhaps Flux has some rough edges on the server. The truth is Facebook doesn't do much server rendering, so they haven't been very concerned about it, and rely on the ecosystem to make it easier.

In traditional Flux, stores are singletons. This means it's hard to separate the data for different requests on the server. Not impossible, but hard. This is why most Flux libraries (as well as the new Flux Utils) now suggest you use classes instead of singletons, so you can instantiate stores per request.

There are still the following problems that you need to solve in Flux (either yourself or with the help of your favorite Flux library such as Flummox or Alt):

  • If stores are classes, how do I create and destroy them with dispatcher per request? When do I register stores?
  • How do I hydrate the data from the stores and later rehydrate it on the client? Do I need to implement special methods for this?

Admittedly Flux frameworks (not vanilla Flux) have solutions to these problems, but I find them overcomplicated. For example, Flummox asks you to implement serialize() and deserialize() in your stores. Alt solves this nicer by providing takeSnapshot() that automatically serializes your state in a JSON tree.

Redux just goes further: since there is just a single store (managed by many reducers), you don't need any special API to manage the (re)hydration. You don't need to “flush” or “hydrate” stores—there's just a single store, and you can read its current state, or create a new store with a new state. Each request gets a separate store instance. Read more about server rendering with Redux.

Again, this is a case of something possible both in Flux and Redux, but Flux libraries solve this problem by introducing a ton of API and conventions, and Redux doesn't even have to solve it because it doesn't have that problem in the first place thanks to conceptual simplicity.

Developer Experience

I didn't actually intend Redux to become a popular Flux library—I wrote it as I was working on my ReactEurope talk on hot reloading with time travel. I had one main objective: make it possible to change reducer code on the fly or even “change the past” by crossing out actions, and see the state being recalculated.

I haven't seen a single Flux library that is able to do this. React Hot Loader also doesn't let you do this—in fact it breaks if you edit Flux stores because it doesn't know what to do with them.

When Redux needs to reload the reducer code, it calls replaceReducer(), and the app runs with the new code. In Flux, data and functions are entangled in Flux stores, so you can't “just replace the functions”. Moreover, you'd have to somehow re-register the new versions with the Dispatcher—something Redux doesn't even have.


Redux has a rich and fast-growing ecosystem. This is because it provides a few extension points such as middleware. It was designed with use cases such as logging, support for Promises, Observables, routing, immutability dev checks, persistence, etc, in mind. Not all of these will turn out to be useful, but it's nice to have access to a set of tools that can be easily combined to work together.


Redux preserves all the benefits of Flux (recording and replaying of actions, unidirectional data flow, dependent mutations) and adds new benefits (easy undo-redo, hot reloading) without introducing Dispatcher and store registration.

Keeping it simple is important because it keeps you sane while you implement higher-level abstractions.

Unlike most Flux libraries, Redux API surface is tiny. If you remove the developer warnings, comments, and sanity checks, it's 99 lines. There is no tricky async code to debug.

You can actually read it and understand all of Redux.

See also my answer on downsides of using Redux compared to Flux.

Override back button to act like home button

Most of the time you need to create a Service to perform something in the background, and your visible Activity simply controls this Service. (I'm sure the Music player works in the same way, so the example in the docs seems a bit misleading.) If that's the case, then your Activity can finish as usual and the Service will still be running.

A simpler approach is to capture the Back button press and call moveTaskToBack(true) as follows:

// 2.0 and above
public void onBackPressed() {

// Before 2.0
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        return true;
    return super.onKeyDown(keyCode, event);

I think the preferred option should be for an Activity to finish normally and be able to recreate itself e.g. reading the current state from a Service if needed. But moveTaskToBack can be used as a quick alternative on occasion.

NOTE: as pointed out by Dave below Android 2.0 introduced a new onBackPressed method, and these recommendations on how to handle the Back button.

How do I save a stream to a file in C#?

Why not use a FileStream object?

public void SaveStreamToFile(string fileFullPath, Stream stream)
    if (stream.Length == 0) return;

    // Create a FileStream object to write a stream to a file
    using (FileStream fileStream = System.IO.File.Create(fileFullPath, (int)stream.Length))
        // Fill the bytes[] array with the stream data
        byte[] bytesInStream = new byte[stream.Length];
        stream.Read(bytesInStream, 0, (int)bytesInStream.Length);

        // Use FileStream object to write to the specified file
        fileStream.Write(bytesInStream, 0, bytesInStream.Length);

Sort an Array by keys based on another Array?

There you go:

function sortArrayByArray(array $array, array $orderArray) {
    $ordered = array();
    foreach ($orderArray as $key) {
        if (array_key_exists($key, $array)) {
            $ordered[$key] = $array[$key];
    return $ordered + $array;

What is the difference between parseInt() and Number()?

I found two links of performance compare among several ways of converting string to int.

str << 0

In Chart.js set chart title, name of x axis and y axis?

In Chart.js version 2.0, it is possible to set labels for axes:

options = {
  scales: {
    yAxes: [{
      scaleLabel: {
        display: true,
        labelString: 'probability'

See Labelling documentation for more details.

Is there an onSelect event or equivalent for HTML <select>?

use jquery:

<select class="target">

    $('.target').change(function() { doSomething(); });

Replace a character at a specific index in a string?

You can overwrite a string, as follows:

String myName = "halftime";
myName = myName.substring(0,4)+'x'+myName.substring(5);  

Note that the string myName occurs on both lines, and on both sides of the second line.

Therefore, even though strings may technically be immutable, in practice, you can treat them as editable by overwriting them.

How to set cell spacing and UICollectionView - UICollectionViewFlowLayout size ratio?

For Swift 3+ and Xcode 9+ Try using this

extension ViewController: UICollectionViewDelegateFlowLayout {

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let collectionWidth = collectionView.bounds.width
    return CGSize(width: collectionWidth/3, height: collectionWidth/3)


func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0


Google Maps API v3 adding an InfoWindow to each marker

You are having a very common closure problem in the for in loop:

Variables enclosed in a closure share the same single environment, so by the time the click callback from the addListener is called, the loop will have run its course and the info variable will be left pointing to the last object, which happens to be the last InfoWindow created.

In this case, one easy way to solve this problem would be to augment your Marker object with the InfoWindow:

var marker = new google.maps.Marker({map: map, position: point, clickable: true}); = new google.maps.InfoWindow({
  content: '<b>Speed:</b> ' + values.inst + ' knots'

google.maps.event.addListener(marker, 'click', function() {, marker);

This can be quite a tricky topic, if you are not familiar with how closures work. You may to check out the following Mozilla article for a brief introduction:

Also keep in mind, that the v3 API allows multiple InfoWindows on the map. If you intend to have just one InfoWindow visible at the time, you should instead use a single InfoWindow object, and then open it and change its content whenever the marker is clicked (Source).

PowerShell Script to Find and Replace for all Files with a Specific Extension

PowerShell is a good choice ;) It is very easy to enumerate files in given directory, read them and process.

The script could look like this:

Get-ChildItem C:\Projects *.config -recurse |
    Foreach-Object {
        $c = ($_ | Get-Content) 
        $c = $c -replace '<add key="Environment" value="Dev"/>','<add key="Environment" value="Demo"/>'
        [IO.File]::WriteAllText($_.FullName, ($c -join "`r`n"))

I split the code to more lines to be readable for you. Note that you could use Set-Content instead of [IO.File]::WriteAllText, but it adds new line at the end. With WriteAllText you can avoid it.

Otherwise the code could look like this: $c | Set-Content $_.FullName.

Having Django serve downloadable files

A "download" is simply an HTTP header change.

See for how to respond with a download.

You only need one URL definition for "/download".

The request's GET or POST dictionary will have the "f=somefile.txt" information.

Your view function will simply merge the base path with the "f" value, open the file, create and return a response object. It should be less than 12 lines of code.

What is the difference between signed and unsigned int

Sometimes we know in advance that the value stored in a given integer variable will always be positive-when it is being used to only count things, for example. In such a case we can declare the variable to be unsigned, as in, unsigned int num student;. With such a declaration, the range of permissible integer values (for a 32-bit compiler) will shift from the range -2147483648 to +2147483647 to range 0 to 4294967295. Thus, declaring an integer as unsigned almost doubles the size of the largest possible value that it can otherwise hold.

Java: Getting a substring from a string starting after a particular character

I think that would be better if we use directly the split function

String toSplit = "/abc/def/ghfj.doc";

String result[] = toSplit.split("/");

String returnValue = result[result.length - 1]; //equals "ghfj.doc"

Why when I transfer a file through SFTP, it takes longer than FTP?

I'm the author of HPN-SSH and I was asked by a commenter here to weigh in. I'd like to start with a couple of background items. First off, it's important to keep in mind that SSHv2 is a multiplexed protocol - multiple channels over a single TCP connection. As such, the SSH channels are essentially unaware of the underlying flow control algorithm used by TCP. This means that SSHv2 has to implement its own flow control algorithm. The most common implementation basically reimplements sliding windows. The means that you have the SSH sliding window riding on top of the TCP sliding window. The end results is that the effective size of the receive buffer is the minimum of the receive buffers of the two sliding windows. Stock OpenSSH has a maximum receive buffer size of 2MB but this really ends up being closer to ~1.2MB. Most modern OSes have a buffer that can grow (using auto-tuning receive buffers) up to an effective size of 4MB. Why does this matter? If the receive buffer size is less than the bandwidth delay product (BDP) then you will never be able to fully fill the pipe regardless of how fast your system is.

This is complicated by the fact that SFTP adds another layer of flow control onto of the TCP and SSH flow controls. SFTP uses a concept of outstanding messages. Each message may be a command, a result of a command, or bulk data flow. The outstanding messages may be up to a specific datagram size. So you end up with what you might as well think of as yet another receive buffer. The size of this receive buffer is datagram size * maximum outstanding messages (both of which may be set on the command line). The default is 32k * 64 (2MB). So when using SFTP you have to make sure that the TCP receive buffer, the SSH receive buffer, and the SFTP receive buffer are all of sufficient size (without being too large or you can have over buffering problems in interactive sessions).

HPN-SSH directly addresses the SSH buffer problem by having a maximum buffer size of around 16MB. More importantly, the buffer dynamically grows to the proper size by polling the proc entry for the TCP connection's buffer size (basically poking a hole between layers 3 and 4). This avoids overbuffering in almost all situations. In SFTP we raise the maximum number of outstanding requests to 256. At least we should be doing that - it looks like that change didn't propagate as expected to the 6.3 patch set (though it is in 6.2. I'll fix that soon). There isn't a 6.4 version because 6.3 patches cleanly against 6.4 (which is a 1 line security fix from 6.3). You can get the patch set from sourceforge.

I know this sounds odd but right sizing the buffers was the single most important change in terms of performance. In spite of what many people think the encryption is not the real source of poor performance in most cases. You can prove this to yourself by transferring data to sources that are increasingly far away (in terms of RTT). You'll notice that the longer the RTT the lower the throughput. That clearly indicates that this is an RTT dependent performance problem.

Anyway, with this change I started seeing improvements of up to 2 orders of magnitude. If you understand TCP you'll understand why this made such a difference. It's not about the size of the datagram or the number of packets or anything like that. It's entire because in order to make efficient use of the network path you must have a receive buffer equal to the amount of data that can be in transit between the two hosts. This also means that you may not see any improvement whatsoever if the path isn't sufficiently fast and long enough. If the BDP is less than 1.2MB HPN-SSH may be of no value to you.

The parallelized AES-CTR cipher is a performance boost on systems with multiple cores if you need to have full encryption end to end. Usually I suggest people (or have control over both the server and client) to use the NONE cipher switch (encrypted authentication, bulk data passed in clear) as most data isn't all that sensitive. However, this only works in non-interactive sessions like SCP. It doesn't work in SFTP.

There are some other performance improvements as well but nothing as important as the right sizing of the buffers and the encryption work. When I get some free time I'll probably pipeline the HMAC process (currently the biggest drag on performance) and do some more minor optimization work.

So if HPN-SSH is so awesome why hasn't OpenSSH adopted it? That's a long story and people who know the OpenBSD team probably already know the answer. I understand many of their reasons - it's a big patch which would require additional work on their end (and they are a small team), they don't care as much about performance as security (though there is no security implications to HPN-SSH), etc etc etc. However, even though OpenSSH doesn't use HPN-SSH Facebook does. So do Google, Yahoo, Apple, most ever large research data center, NASA, NOAA, the government, the military, and most financial institutions. It's pretty well vetted at this point.

If anyone has any questions feel free to ask but I may not be keeping up to date on this forum. You can always send me mail via the HPN-SSH email address (google it).

How should I do integer division in Perl?

you can:

use integer;

it is explained by Michael Ratanapintha or else use manually:



notice, 'int' is not casting. this is function for converting number to integer form. this is because Perl 5 does not have separate integer division. exception is when you 'use integer'. Then you will lose real division.

Checking Bash exit status of several commands efficiently

Instead of creating runner functions or using set -e, use a trap:

trap 'echo "error"; do_cleanup failed; exit' ERR
trap 'echo "received signal to stop"; do_cleanup interrupted; exit' SIGQUIT SIGTERM SIGINT

do_cleanup () { rm tempfile; echo "$1 $(date)" >> script_log; }


The trap even has access to the line number and the command line of the command that triggered it. The variables are $BASH_LINENO and $BASH_COMMAND.

UIBarButtonItem in navigation bar programmatically?

iOS 11

Setting a custom button using constraint:

let buttonWidth = CGFloat(30)
let buttonHeight = CGFloat(30)

let button = UIButton(type: .custom)
button.setImage(UIImage(named: "img name"), for: .normal)
button.addTarget(self, action: #selector(buttonTapped(sender:)), for: .touchUpInside)
button.widthAnchor.constraint(equalToConstant: buttonWidth).isActive = true
button.heightAnchor.constraint(equalToConstant: buttonHeight).isActive = true

self.navigationItem.rightBarButtonItem = UIBarButtonItem.init(customView: button)

How to get base64 encoded data from html image

You can also use the FileReader class :

    var reader = new FileReader();
    reader.onload = function (e) {
        var data = this.result;
    reader.readAsDataURL( file );

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

A simple use:

Type typeYouWant = Type.GetType("NamespaceOfType.TypeName, AssemblyName");


Type dogClass = Type.GetType("Animals.Dog, Animals");

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

With bootstrap you can use

<a href="#/new-page.html" class="btn btn-primary">

Perl regular expression (using a variable as a search string with Perl operator characters included)

You can use quotemeta (\Q \E) if your Perl is version 5.16 or later, but if below you can simply avoid using a regular expression at all.

For example, by using the index command:

if (index($text_to_search, $search_string) > -1) {
    print "wee";

Getting an object array from an Angular service

Take a look at your code :

 getUsers(): Observable<User[]> {
        return Observable.create(observer => {
            this.http.get('').map(response => response.json();

and code from (BTW. really good tutorial, you should check it out)

 getHeroes(): Promise<Hero[]> {
    return this.http.get(this.heroesUrl)
               .then(response => response.json().data as Hero[])

The HttpService inside Angular2 already returns an observable, sou don't need to wrap another Observable around like you did here:

   return Observable.create(observer => {
        this.http.get('').map(response => response.json()

Try to follow the guide in link that I provided. You should be just fine when you study it carefully.


First of all WHERE you log the this.users variable? JavaScript isn't working that way. Your variable is undefined and it's fine, becuase of the code execution order!

Try to do it like this:

  getUsers(): void {
            .then(users => {
               this.users = users
               console.log('this.users=' + this.users);


See where the console.log(...) is!

Try to resign from toPromise() it's seems to be just for ppl with no RxJs background.

Catch another link: Build your service once again with RxJs observables.

Loop through a comma-separated shell variable

Here is an alternative tr based solution that doesn't use echo, expressed as a one-liner.

for v in $(tr ',' '\n' <<< "$var") ; do something_with "$v" ; done

It feels tidier without echo but that is just my personal preference.

Always pass weak reference of self into block in ARC?

As Leo points out, the code you added to your question would not suggest a strong reference cycle (a.k.a., retain cycle). One operation-related issue that could cause a strong reference cycle would be if the operation is not getting released. While your code snippet suggests that you have not defined your operation to be concurrent, but if you have, it wouldn't be released if you never posted isFinished, or if you had circular dependencies, or something like that. And if the operation isn't released, the view controller wouldn't be released either. I would suggest adding a breakpoint or NSLog in your operation's dealloc method and confirm that's getting called.

You said:

I understand the notion of retain cycles, but I am not quite sure what happens in blocks, so that confuses me a little bit

The retain cycle (strong reference cycle) issues that occur with blocks are just like the retain cycle issues you're familiar with. A block will maintain strong references to any objects that appear within the block, and it will not release those strong references until the block itself is released. Thus, if block references self, or even just references an instance variable of self, that will maintain strong reference to self, that is not resolved until the block is released (or in this case, until the NSOperation subclass is released.

For more information, see the Avoid Strong Reference Cycles when Capturing self section of the Programming with Objective-C: Working with Blocks document.

If your view controller is still not getting released, you simply have to identify where the unresolved strong reference resides (assuming you confirmed the NSOperation is getting deallocated). A common example is the use of a repeating NSTimer. Or some custom delegate or other object that is erroneously maintaining a strong reference. You can often use Instruments to track down where objects are getting their strong references, e.g.:

record reference counts in Xcode 6

Or in Xcode 5:

record reference counts in Xcode 5

How to change column datatype from character to numeric in PostgreSQL 8.4

If your VARCHAR column contains empty strings (which are not the same as NULL for PostgreSQL as you might recall) you will have to use something in the line of the following to set a default:

            USING COALESCE(NULLIF(code, '')::NUMERIC, 0);

(found with the help of this answer)

C: scanf to array

int main()
  int array[11];
  printf("Write down your ID number!\n");
  for(int i=0;i<id_length;i++)
  scanf("%d", &array[i]);
  if (array[0]==1)
    printf("\nThis person is a male.");
  else if (array[0]==2)
    printf("\nThis person is a female.");
  return 0;

Save classifier to disk in scikit-learn

sklearn.externals.joblib has been deprecated since 0.21 and will be removed in v0.23:

/usr/local/lib/python3.7/site-packages/sklearn/externals/joblib/ FutureWarning: sklearn.externals.joblib is deprecated in 0.21 and will be removed in 0.23. Please import this functionality directly from joblib, which can be installed with: pip install joblib. If this warning is raised when loading pickled models, you may need to re-serialize those models with scikit-learn 0.21+.
warnings.warn(msg, category=FutureWarning)

Therefore, you need to install joblib:

pip install joblib

and finally write the model to disk:

import joblib
from sklearn.datasets import load_digits
from sklearn.linear_model import SGDClassifier

digits = load_digits()
clf = SGDClassifier().fit(,

with open('myClassifier.joblib.pkl', 'wb') as f:
    joblib.dump(clf, f, compress=9)

Now in order to read the dumped file all you need to run is:

with open('myClassifier.joblib.pkl', 'rb') as f:
    my_clf = joblib.load(f)

Package opencv was not found in the pkg-config search path

with opencv 4.0;

  • add -DOPENCV_GENERATE_PKGCONFIG=ON to build arguments
  • pkg-config --cflags --libs opencv4 instead of opencv

jQuery UI 1.10: dialog and zIndex option

moveToTop is the proper way.

z-Index is not correct. It works initially, but multiple dialogs will continue to float underneath the one you altered with z-index. No good.

Make footer stick to bottom of page correctly

Why not using: { position: fixed; bottom: 0 } ?

Convert NSArray to NSString in Objective-C

Swift 3.0 solution:

let string = array.joined(separator: " ")

Where are my postgres *.conf files?


sudo updatedb

followed by

locate postgresql.conf

m2e error in MavenArchiver.getManifest()

I solved this error in pom.xml by adding the below code

spring-rest-demo org.apache.maven.plugins maven-war-plugin 2.6

The action or event has been blocked by Disabled Mode

From access help:

Stop Disabled Mode from blocking a query If you try to run an append query and it seems like nothing happens, check the Access status bar for the following message:

This action or event has been blocked by Disabled Mode.

To stop Disabled Mode from blocking the query, you must enable the database content. You use the Options button in the Message Bar to enable the query.

Enable the append query In the Message Bar, click Options. In the Microsoft Office Security Options dialog box, click Enable this content, and then click OK. If you don't see the Message Bar, it may be hidden. You can show it, unless it has also been disabled. If the Message Bar has been disabled, you can enable it.

Show the Message Bar If the Message Bar is already visible, you can skip this step.

On the Database Tools tab, in the Show/Hide group, select the Message Bar check box. If the Message Bar check box is disabled, you will have to enable it.

Enable the Message Bar If the Message Bar check box is enabled, you can skip this step.

Click the Microsoft Office Button , and then click Access Options. In the left pane of the Access Options dialog box, click Trust Center. In the right pane, under Microsoft Office Access Trust Center, click Trust Center Settings. In the left pane of the Trust Center dialog box, click Message Bar. In the right pane, click Show the Message Bar in all applications when content has been blocked, and then click OK. Close and reopen the database to apply the changed setting. Note When you enable the append query, you also enable all other database content.

For more information about Access security, see the article Help secure an Access 2007 database.

Using the "With Clause" SQL Server 2008

There are two types of WITH clauses:

Here is the FizzBuzz in SQL form, using a WITH common table expression (CTE).

;WITH mil AS (
 SELECT TOP 1000000 ROW_NUMBER() OVER ( ORDER BY c.column_id ) [n]
 FROM master.sys.all_columns as c
 CROSS JOIN master.sys.all_columns as c2
             CASE WHEN n  % 5 = 0 THEN 'FizzBuzz' ELSE 'Fizz' END
        WHEN n % 5 = 0 THEN 'Buzz'
        ELSE CAST(n AS char(6))
     END + CHAR(13)
 FROM mil

Here is a select statement also using a WITH clause

SELECT * FROM orders WITH (NOLOCK) where order_id = 123

ImportError in importing from sklearn: cannot import name check_build

>>> from sklearn import preprocessing, metrics, cross_validation

Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    from sklearn import preprocessing, metrics, cross_validation
  File "D:\Python27\lib\site-packages\sklearn\", line 31, in <module>
    from . import __check_build
ImportError: cannot import name __check_build
>>> ================================ RESTART ================================
>>> from sklearn import preprocessing, metrics, cross_validation

So, simply try to restart the shell!

What is Func, how and when is it used

Func<T1,R> and the other predefined generic Func delegates (Func<T1,T2,R>, Func<T1,T2,T3,R> and others) are generic delegates that return the type of the last generic parameter.

If you have a function that needs to return different types, depending on the parameters, you can use a Func delegate, specifying the return type.

How do you get a directory listing sorted by creation date in python?

This was my version:

import os

folder_path = r'D:\Movies\extra\new\dramas' # your path
os.chdir(folder_path) # make the path active
x = sorted(os.listdir(), key=os.path.getctime)  # sorted using creation time

folder = 0

for folder in range(len(x)):
    print(x[folder]) # print all the foldername inside the folder_path
    folder = +1

Output PowerShell variables to a text file

I was lead here in my Google searching. In a show of good faith I have included what I pieced together from parts of this code and other code I've gathered along the way.

# This script is useful if you have attributes or properties that span across several commandlets_x000D_
# and you wish to export a certain data set but all of the properties you wish to export are not_x000D_
# included in only one commandlet so you must use more than one to export the data set you want_x000D_
# Created: Joshua Biddle 08/24/2017_x000D_
# Edited: Joshua Biddle 08/24/2017_x000D_
$A = Get-ADGroupMember "YourGroupName"_x000D_
# Construct an out-array to use for data export_x000D_
$Results = @()_x000D_
foreach ($B in $A)_x000D_
  # Construct an object_x000D_
        $myobj = Get-ADuser $B.samAccountName -Properties ScriptPath,Office_x000D_
  # Fill the object_x000D_
  $Properties = @{_x000D_
  samAccountName = $myobj.samAccountName_x000D_
  Name = $myobj.Name _x000D_
  Office = $myobj.Office _x000D_
  ScriptPath = $myobj.ScriptPath_x000D_
        # Add the object to the out-array_x000D_
        $Results += New-Object psobject -Property $Properties_x000D_
  # Wipe the object just to be sure_x000D_
        $myobj = $null_x000D_
# After the loop, export the array to CSV_x000D_
$Results | Select "samAccountName", "Name", "Office", "ScriptPath" | Export-CSV "C:\Temp\YourData.csv"


Installing python module within code

You can also use something like:

import pip

def install(package):
    if hasattr(pip, 'main'):
        pip.main(['install', package])
        pip._internal.main(['install', package])

# Example
if __name__ == '__main__':

Is it possible to decrypt SHA1

SHA1 is a cryptographic hash function, so the intention of the design was to avoid what you are trying to do.

However, breaking a SHA1 hash is technically possible. You can do so by just trying to guess what was hashed. This brute-force approach is of course not efficient, but that's pretty much the only way.

So to answer your question: yes, it is possible, but you need significant computing power. Some researchers estimate that it costs $70k - $120k.

As far as we can tell today, there is also no other way but to guess the hashed input. This is because operations such as mod eliminate information from your input. Suppose you calculate mod 5 and you get 0. What was the input? Was it 0, 5 or 500? You see, you can't really 'go back' in this case.

How to cherry-pick multiple commits

Another variant worth mentioning is that if you want the last n commits from a branch, the ~ syntax can be useful:

git cherry-pick some-branch~4..some-branch

In this case, the above command would pick the last 4 commits from a branch called some-branch (though you could also use a commit hash in place of a branch name)

How to add Action bar options menu in Android Fragments

in AndroidManifest.xml set theme holo like this:

android:name="your Fragment or activity"
android:theme="@android:style/Theme.Holo" >

How to remove border of drop down list : CSS

You can't style the drop down box itself, only the input field. The box is rendered by the operating system.

enter image description here

If you want more control over the look of your input fields, you can always look into JavaScript solutions.

If, however, your intent was to remove the border from the input itself, your selector is wrong. Try this instead:

select#xyz {
    border: none;

How to use UIPanGestureRecognizer to move object? iPhone/iPad

Casting my hat into the ring a couple years later.

Will need to save the beginning center of the image view:

var panBegin:

Then update the new center using a transform:

if recognizer.state == .began {
     panBegin = imageView!.center

} else if recognizer.state == .ended {
    panBegin =

} else if recognizer.state == .changed {
    let translation = recognizer.translation(in: view)
    let panOffsetTransform = CGAffineTransform( translationX: translation.x, y: translation.y)

    imageView!.center = panBegin.applying(panOffsetTransform)

Select multiple columns from a table, but group by one

I had a similar problem to the OP. Then I saw the answer from @Urs Marian which helped a lot. But additionally what I was looking for is, when there are multiple values in a column and they will be grouped, how I can get the last submitted value (e.g. ordered by a date/id column).


We have following table structure:

CREATE TABLE tablename(
    [msgid] [int] NOT NULL,
    [userid] [int] NOT NULL,
    [username] [varchar](70) NOT NULL,
    [message] [varchar](5000) NOT NULL

Now there are at least two datasets in the table:

| msgid | userid | username | message |
|     1 |      1 | userA    | hello   |
|     2 |      1 | userB    | world   |

Therefore following SQL script does work (checked on MSSQL) to group it, also if the same userid has different username values. In the example below, the username with the highest msgid will be shown:

SELECT m.userid, 
(select top 1 username from table where userid = m.userid order by msgid desc) as username,
count(*) as messages
FROM tablename m
GROUP BY m.userid
ORDER BY count(*) DESC

How do I load external fonts into an HTML document?

If you want to support more browsers than the CSS3 fancy, you can look at the open source library cufon javascript library

And here is the API, if you want to do more funky stuff.

Major Pro: Allows you to do what you want / need.

Major Con: Disallows text selection in some browsers, so use is appropiate on header texts (but you can use it in all your site if you want)

How to run specific test cases in GoogleTest

You could use advanced options to run Google tests.

To run only some unit tests you could use --gtest_filter=Test_Cases1* command line option with value that accepts the * and ? wildcards for matching with multiple tests. I think it will solve your problem.


Well, the question was how to run specific test cases. Integration of gtest with your GUI is another thing, which I can't really comment, because you didn't provide details of your approach. However I believe the following approach might be a good start:

  1. Get all testcases by running tests with --gtest_list_tests
  2. Parse this data into your GUI
  3. Select test cases you want ro run
  4. Run test executable with option --gtest_filter

Time complexity of Euclid's Algorithm

Here is the analysis in the book Data Structures and Algorithm Analysis in C by Mark Allen Weiss (second edition, 2.4.4):

Euclid's algorithm works by continually computing remainders until 0 is reached. The last nonzero remainder is the answer.

Here is the code:

unsigned int Gcd(unsigned int M, unsigned int N)

    unsigned int Rem;
    while (N > 0) {
        Rem = M % N;
        M = N;
        N = Rem;
    Return M;

Here is a THEOREM that we are going to use:

If M > N, then M mod N < M/2.


There are two cases. If N <= M/2, then since the remainder is smaller than N, the theorem is true for this case. The other case is N > M/2. But then N goes into M once with a remainder M - N < M/2, proving the theorem.

So, we can make the following inference:

Variables    M      N      Rem

initial      M      N      M%N

1 iteration  N     M%N    N%(M%N)

2 iterations M%N  N%(M%N) (M%N)%(N%(M%N)) < (M%N)/2

So, after two iterations, the remainder is at most half of its original value. This would show that the number of iterations is at most 2logN = O(logN).

Note that, the algorithm computes Gcd(M,N), assuming M >= N.(If N > M, the first iteration of the loop swaps them.)

SQL Error: ORA-12899: value too large for column

As mentioned, the error message shows you the exact problem: you are passing 25 characters into a field set up to hold 20. You might also want to consider defining the columns a little more precisely. You can define whether the VARCHAR2 column will store a certain number of bytes or characters. You may encounter a problem in the future where you try to insert a multi byte character into the field, for example this is 5 characters in length but it won't fit into 5 bytes: 'ÀÈÌÕÛ'

Here is an example:

CREATE TABLE Customers(CustomerID  VARCHAR2(9 BYTE), ...


CREATE TABLE Customers(CustomerID  VARCHAR2(9 CHAR), ...

How do I import other TypeScript files?

Quick Easy Process in Visual Studio

Drag and Drop the file with .ts extension from solution window to editor, it will generate inline reference code like..

/// <reference path="../../components/someclass.ts"/>

div hover background-color change?

div hover background color change

Try like this:


Why should I use a pointer rather than the object itself?

A pointer directly references the memory location of an object. Java has nothing like this. Java has references that reference the location of object through hash tables. You cannot do anything like pointer arithmetic in Java with these references.

To answer your question, it's just your preference. I prefer using the Java-like syntax.

jQuery get value of select onChange

Try this-

$('select').on('change', function() {_x000D_
  alert( this.value );_x000D_
<script src=""></script>_x000D_
    <option value="1">One</option>_x000D_
    <option value="2">Two</option>_x000D_

You can also reference with onchange event-

function getval(sel)_x000D_
<select onchange="getval(this);">_x000D_
    <option value="1">One</option>_x000D_
    <option value="2">Two</option>_x000D_

How to add a border just on the top side of a UIView

Added capability for rounded corners to Adam Waite's original post, and the multiple edits

Important!: Don't forgot to add 'label.layoutIfNeeded()' right before calling 'addborder' as previously commented

Note: I've only tested this on UILabels.

extension CALayer {
    enum BorderSide {
        case top
        case right
        case bottom
        case left
        case notRight
        case notLeft
        case topAndBottom
        case all
    enum Corner {
        case topLeft
        case topRight
        case bottomLeft
        case bottomRight
    func addBorder(side: BorderSide, thickness: CGFloat, color: CGColor, maskedCorners: CACornerMask? = nil) {
        var topWidth = frame.size.width; var bottomWidth = topWidth
        var leftHeight = frame.size.height; var rightHeight = leftHeight
        var topXOffset: CGFloat = 0; var bottomXOffset: CGFloat = 0
        var leftYOffset: CGFloat = 0; var rightYOffset: CGFloat = 0
        // Draw the corners and set side offsets
        switch maskedCorners {
        case [.layerMinXMinYCorner, .layerMaxXMinYCorner]: // Top only
            addCorner(.topLeft, thickness: thickness, color: color)
            addCorner(.topRight, thickness: thickness, color: color)
            topWidth -= cornerRadius*2
            leftHeight -= cornerRadius; rightHeight -= cornerRadius
            topXOffset = cornerRadius; leftYOffset = cornerRadius; rightYOffset = cornerRadius
        case [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]: // Bottom only
            addCorner(.bottomLeft, thickness: thickness, color: color)
            addCorner(.bottomRight, thickness: thickness, color: color)
            bottomWidth -= cornerRadius*2
            leftHeight -= cornerRadius; rightHeight -= cornerRadius
            bottomXOffset = cornerRadius
        case [.layerMinXMinYCorner, .layerMinXMaxYCorner]: // Left only
            addCorner(.topLeft, thickness: thickness, color: color)
            addCorner(.bottomLeft, thickness: thickness, color: color)
            topWidth -= cornerRadius; bottomWidth -= cornerRadius
            leftHeight -= cornerRadius*2
            leftYOffset = cornerRadius; topXOffset = cornerRadius; bottomXOffset = cornerRadius;
        case [.layerMaxXMinYCorner, .layerMaxXMaxYCorner]: // Right only
            addCorner(.topRight, thickness: thickness, color: color)
            addCorner(.bottomRight, thickness: thickness, color: color)
            topWidth -= cornerRadius; bottomWidth -= cornerRadius
            rightHeight -= cornerRadius*2
            rightYOffset = cornerRadius
        case [.layerMaxXMinYCorner, .layerMaxXMaxYCorner,  // All
              .layerMinXMaxYCorner, .layerMinXMinYCorner]:
            addCorner(.topLeft, thickness: thickness, color: color)
            addCorner(.topRight, thickness: thickness, color: color)
            addCorner(.bottomLeft, thickness: thickness, color: color)
            addCorner(.bottomRight, thickness: thickness, color: color)
            topWidth -= cornerRadius*2; bottomWidth -= cornerRadius*2
            topXOffset = cornerRadius; bottomXOffset = cornerRadius
            leftHeight -= cornerRadius*2; rightHeight -= cornerRadius*2
            leftYOffset = cornerRadius; rightYOffset = cornerRadius
        default: break
        // Draw the sides
        switch side {
        case .top:
            addLine(x: topXOffset, y: 0, width: topWidth, height: thickness, color: color)
        case .right:
            addLine(x: frame.size.width - thickness, y: rightYOffset, width: thickness, height: rightHeight, color: color)
        case .bottom:
            addLine(x: bottomXOffset, y: frame.size.height - thickness, width: bottomWidth, height: thickness, color: color)
        case .left:
            addLine(x: 0, y: leftYOffset, width: thickness, height: leftHeight, color: color)

        // Multiple Sides
        case .notRight:
            addLine(x: topXOffset, y: 0, width: topWidth, height: thickness, color: color)
            addLine(x: 0, y: leftYOffset, width: thickness, height: leftHeight, color: color)
            addLine(x: bottomXOffset, y: frame.size.height - thickness, width: bottomWidth, height: thickness, color: color)

        case .notLeft:
            addLine(x: topXOffset, y: 0, width: topWidth, height: thickness, color: color)
            addLine(x: frame.size.width - thickness, y: rightYOffset, width: thickness, height: rightHeight, color: color)
            addLine(x: bottomXOffset, y: frame.size.height - thickness, width: bottomWidth, height: thickness, color: color)

        case .topAndBottom:
            addLine(x: topXOffset, y: 0, width: topWidth, height: thickness, color: color)
            addLine(x: bottomXOffset, y: frame.size.height - thickness, width: bottomWidth, height: thickness, color: color)

        case .all:
            addLine(x: topXOffset, y: 0, width: topWidth, height: thickness, color: color)
            addLine(x: frame.size.width - thickness, y: rightYOffset, width: thickness, height: rightHeight, color: color)
            addLine(x: bottomXOffset, y: frame.size.height - thickness, width: bottomWidth, height: thickness, color: color)
            addLine(x: 0, y: leftYOffset, width: thickness, height: leftHeight, color: color)
    private func addLine(x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat, color: CGColor) {
        let border = CALayer()
        border.frame = CGRect(x: x, y: y, width: width, height: height)
        border.backgroundColor = color
    private func addCorner(_ corner: Corner, thickness: CGFloat, color: CGColor) {
        // Set default to top left
        let width = frame.size.width; let height = frame.size.height
        var x = cornerRadius
        var y = cornerRadius
        var startAngle: CGFloat = .pi; var endAngle: CGFloat = .pi*3/2
        switch corner {
        case .bottomLeft:
            y = height - cornerRadius 
            startAngle = .pi/2; endAngle = .pi
        case .bottomRight:
            x = width - cornerRadius
            y = height - cornerRadius
            startAngle = 0; endAngle = .pi/2
        case .topRight:
            x = width - cornerRadius
            startAngle = .pi*3/2; endAngle = 0
        default: break
        let cornerPath = UIBezierPath(arcCenter: CGPoint(x: x, y: y),
                                      radius: cornerRadius - thickness,
                                      startAngle: startAngle,
                                      endAngle: endAngle,
                                      clockwise: true)

        let cornerShape = CAShapeLayer()
        cornerShape.path = cornerPath.cgPath
        cornerShape.lineWidth = thickness
        cornerShape.strokeColor = color
        cornerShape.fillColor = nil

Get all dates between two dates in SQL Server

My first suggestion would be use your calendar table, if you don't have one, then create one. They are very useful. Your query is then as simple as:

DECLARE @MinDate DATE = '20140101',
        @MaxDate DATE = '20140106';

FROM    dbo.Calendar
WHERE   Date >= @MinDate
AND     Date < @MaxDate;

If you don't want to, or can't create a calendar table you can still do this on the fly without a recursive CTE:

DECLARE @MinDate DATE = '20140101',
        @MaxDate DATE = '20140106';

SELECT  TOP (DATEDIFF(DAY, @MinDate, @MaxDate) + 1)
        Date = DATEADD(DAY, ROW_NUMBER() OVER(ORDER BY a.object_id) - 1, @MinDate)
FROM    sys.all_objects a
        CROSS JOIN sys.all_objects b;

For further reading on this see:

With regard to then using this sequence of dates in a cursor, I would really recommend you find another way. There is usually a set based alternative that will perform much better.

So with your data:

  date   | it_cd | qty 
24-04-14 |  i-1  | 10 
26-04-14 |  i-1  | 20

To get the quantity on 28-04-2014 (which I gather is your requirement), you don't actually need any of the above, you can simply use:

SELECT  TOP 1 date, it_cd, qty 
WHERE   it_cd = 'i-1'
AND     Date <= '20140428'

If you don't want it for a particular item:

SELECT  date, it_cd, qty 
FROM    (   SELECT  date, 
                    RowNumber = ROW_NUMBER() OVER(PARTITION BY ic_id 
                                                    ORDER BY date DESC)
            FROM    T
            WHERE   Date  <= '20140428'
        ) T
WHERE   RowNumber = 1;

How do you count the number of occurrences of a certain substring in a SQL varchar?

I finally write this function that should cover all the possible situations, adding a char prefix and suffix to the input. this char is evaluated to be different to any of the char conteined in the search parameter, so it can't affect the result.

CREATE FUNCTION [dbo].[CountOccurrency]
@Input nvarchar(max),
@Search nvarchar(max)
    declare @SearhLength as int = len('-' + @Search + '-') -2;
    declare @conteinerIndex as int = 255;
    declare @conteiner as char(1) = char(@conteinerIndex);
    WHILE ((CHARINDEX(@conteiner, @Search)>0) and (@conteinerIndex>0))
        set @conteinerIndex = @conteinerIndex-1;
        set @conteiner = char(@conteinerIndex);
    set @Input = @conteiner + @Input + @conteiner
    RETURN (len(@Input) - len(replace(@Input, @Search, ''))) / @SearhLength


select dbo.CountOccurrency('a,b,c,d ,', ',')

Have border wrap around text

Try this and see if you get what you are aiming for:

<div id='page' style='width: 600px'>_x000D_
  <h1 style='border:2px black solid; font-size:42px; width:fit-content; width:-webkit-fit-content; width:-moz-fit-content;'>Title</h1>_x000D_

How can I set a DateTimePicker control to a specific date?

Can't figure out why, but in some circumstances if you have bound DataTimePicker and BindingSource contol is postioned to a new record, setting to Value property doesn't affect to bound field, so when you try to commit changes via EndEdit() method of BindingSource, you receive Null value doesn't allowed error. I managed this problem setting direct DataRow field.

Create a mocked list by mockito

OK, this is a bad thing to be doing. Don't mock a list; instead, mock the individual objects inside the list. See Mockito: mocking an arraylist that will be looped in a for loop for how to do this.

Also, why are you using PowerMock? You don't seem to be doing anything that requires PowerMock.

But the real cause of your problem is that you are using when on two different objects, before you complete the stubbing. When you call when, and provide the method call that you are trying to stub, then the very next thing you do in either Mockito OR PowerMock is to specify what happens when that method is called - that is, to do the thenReturn part. Each call to when must be followed by one and only one call to thenReturn, before you do any more calls to when. You made two calls to when without calling thenReturn - that's your error.

Matplotlib: Specify format of floats for tick labels

See the relevant documentation in general and specifically

from matplotlib.ticker import FormatStrFormatter

fig, ax = plt.subplots()


enter image description here

if condition in sql server update query

this worked great:

  column_A = CASE WHEN @flag = '1' THEN column_A + @new_value ELSE column_A END,
  column_B = CASE WHEN @flag = '0' THEN column_B + @new_value ELSE column_B END
    ID = @ID

websocket closing connection automatically

Since @Doua Beri is experiencing connection close even when there are 1 Hz SENDs, it may be instead be due to size limits on messages.

This passage from Spring's WebSockets may be useful, with my emphasis ...

Although in theory a WebSocket message can be almost unlimited in size, in practice WebSocket servers impose limits — for example, 8K on Tomcat and 64K on Jetty. For this reason STOMP clients such as stomp.js split larger STOMP messages at 16K boundaries and send them as multiple WebSocket messages thus requiring the server to buffer and re-assemble.

How to align checkboxes and their labels consistently cross-browsers

try this code

input[type="checkbox"] {
    -moz-appearance: checkbox;
    -webkit-appearance: checkbox;
    vertical-align: middle;
    top: -1px;
    bottom: 1px;
    *overflow: hidden;
    box-sizing: border-box; /* 1 */
    *height: 13px; /* Removes excess padding in IE 7 */
    *width: 13px;
    background: #fff;

Are PHP short tags acceptable to use?

<?php ?> are much better to use since developers of this programming language has massively updated their core-language. You can see the difference between the short tags and long tags.

Short tags will be highlighted as light red while the longer ones are highlighted darker!

However, echoing something out, for example: <?=$variable;?> is fine. But prefer the longer tags. <?php echo $variable;?>

SyntaxError: Unexpected token function - Async Await Nodejs

Async functions are not supported by Node versions older than version 7.6.

You'll need to transpile your code (e.g. using Babel) to a version of JS that Node understands if you are using an older version.

That said, the current (2018) LTS version of Node.js is 8.x, so if you are using an earlier version you should very strongly consider upgrading.

Styling mat-select in Angular Material

Working solution is by using in-build: panelClass attribute and set styles in global style.css (with !important):

/* style.css */
.matRole .mat-option-text {
  height: 4em !important;
<mat-select panelClass="matRole">...

How to align a div to the top of its parent but keeping its inline-block behaviour?

As others have said, vertical-align: top is your friend.

As a bonus here is a forked fiddle with added enhancements that make it work in Internet Explorer 6 and Internet Explorer 7 too ;)

Example: here

Set default host and port for ng serve in config file

If your are on windows you can do it this way :

  1. In your project root directory, Create file run.bat
  2. Add your command with your choice of configurations in this file. For Example

ng serve --host --open

  1. Now you can click and open this file whenever you want to serve.

This not standard way but comfortable to use (which I feel).

Equal sized table cells to fill the entire width of the containing table

You don't even have to set a specific width for the cells, table-layout: fixed suffices to spread the cells evenly.

ul {_x000D_
    width: 100%;_x000D_
    display: table;_x000D_
    table-layout: fixed;_x000D_
    border-collapse: collapse;_x000D_
li {_x000D_
    display: table-cell;_x000D_
    text-align: center;_x000D_
    border: 1px solid hotpink;_x000D_
    vertical-align: middle;_x000D_
    word-wrap: break-word;_x000D_

Note that for table-layout to work the table styled element must have a width set (100% in my example).

How do I import global modules in Node? I get "Error: Cannot find module <module>"?

You can use npm link to create a symbolic link to your global package in your projects folder.


$ npm install -g express
$ cd [local path]/project
$ npm link express

All it does is create a local node_modules folder and then create a symlink express -> [global directory]/node_modules/express which can then be resolved by require('express')

Eclipse error "Could not find or load main class"

I faced similar problem in my maven webapp project after spending nearly one hour , I found a solution which worked for me .I typed the following maven command and It worked

mvn clean install -U
I dont know the exact reason behind it.

Is ASCII code 7-bit or 8-bit?

ASCII was indeed originally conceived as a 7-bit code. This was done well before 8-bit bytes became ubiquitous, and even into the 1990s you could find software that assumed it could use the 8th bit of each byte of text for its own purposes ("not 8-bit clean"). Nowadays people think of it as an 8-bit coding in which bytes 0x80 through 0xFF have no defined meaning, but that's a retcon.

There are dozens of text encodings that make use of the 8th bit; they can be classified as ASCII-compatible or not, and fixed- or variable-width. ASCII-compatible means that regardless of context, single bytes with values from 0x00 through 0x7F encode the same characters that they would in ASCII. You don't want to have anything to do with a non-ASCII-compatible text encoding if you can possibly avoid it; naive programs expecting ASCII tend to misinterpret them in catastrophic, often security-breaking fashion. They are so deprecated nowadays that (for instance) HTML5 forbids their use on the public Web, with the unfortunate exception of UTF-16. I'm not going to talk about them any more.

A fixed-width encoding means what it sounds like: all characters are encoded using the same number of bytes. To be ASCII-compatible, a fixed-with encoding must encode all its characters using only one byte, so it can have no more than 256 characters. The most common such encoding nowadays is Windows-1252, an extension of ISO 8859-1.

There's only one variable-width ASCII-compatible encoding worth knowing about nowadays, but it's very important: UTF-8, which packs all of Unicode into an ASCII-compatible encoding. You really want to be using this if you can manage it.

As a final note, "ASCII" nowadays takes its practical definition from Unicode, not its original standard (ANSI X3.4-1968), because historically there were several dozen variations on the ASCII 127-character repertoire -- for instance, some of the punctuation might be replaced with accented letters to facilitate the transmission of French text. Nowadays all of those variations are obsolescent, and when people say "ASCII" they mean that the bytes with value 0x00 through 0x7F encode Unicode codepoints U+0000 through U+007F. This will probably only matter to you if you ever find yourself writing a technical standard.

If you're interested in the history of ASCII and the encodings that preceded it, start with the paper "The Evolution of Character Codes, 1874-1968" (samizdat copy at and then chase its references (many of which are not available online and may be hard to find even with access to a university library, I regret to say).

Serializing enums with Jackson

In Spring Boot 2, the easiest way is to declare in your


and define the toString() method of your enums.

TypeError: $(...).autocomplete is not a function

In my exprience I added two Jquery libraries in my file.The versions were jquery 1.11.1 and 2.1.Suddenly I took out 2.1 Jquery from my code. Then ran it and was working for me well. After trying out the first answer. please check out your file like I said above.

Ubuntu: OpenJDK 8 - Unable to locate package

As you can see I only have java 1.7 installed (on a Ubuntu 14.04 machine).

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64

To install Java 8, I did,

sudo add-apt-repository ppa:openjdk-r/ppa
sudo apt-get update
sudo apt-get install openjdk-8-jdk

Afterwards, now I have java 7 and 8,

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64
java-1.8.0-openjdk-amd64 1069 /usr/lib/jvm/java-1.8.0-openjdk-amd64

BONUS ADDED (how to switch between different versions)

  • run the follwing command from the terminal:

sudo update-alternatives --config java

There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
  0            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      auto mode
  1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      manual mode
* 2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1069      manual mode

Press enter to keep the current choice[*], or type selection number:

As you can see I'm running open jdk 8. To switch to to jdk 7, press 1 and hit the Enter key. Do the same for javac as well with, sudo update-alternatives --config javac.

Check versions to confirm the change: java -version and javac -version.

What is a predicate in c#?

Predicate<T> is a functional construct providing a convenient way of basically testing if something is true of a given T object.

For example suppose I have a class:

class Person {
    public string Name { get; set; }
    public int Age { get; set; }

Now let's say I have a List<Person> people and I want to know if there's anyone named Oscar in the list.

Without using a Predicate<Person> (or Linq, or any of that fancy stuff), I could always accomplish this by doing the following:

Person oscar = null;
foreach (Person person in people) {
    if (person.Name == "Oscar") {
        oscar = person;

if (oscar != null) {
    // Oscar exists!

This is fine, but then let's say I want to check if there's a person named "Ruth"? Or a person whose age is 17?

Using a Predicate<Person>, I can find these things using a LOT less code:

Predicate<Person> oscarFinder = (Person p) => { return p.Name == "Oscar"; };
Predicate<Person> ruthFinder = (Person p) => { return p.Name == "Ruth"; };
Predicate<Person> seventeenYearOldFinder = (Person p) => { return p.Age == 17; };

Person oscar = people.Find(oscarFinder);
Person ruth = people.Find(ruthFinder);
Person seventeenYearOld = people.Find(seventeenYearOldFinder);

Notice I said a lot less code, not a lot faster. A common misconception developers have is that if something takes one line, it must perform better than something that takes ten lines. But behind the scenes, the Find method, which takes a Predicate<T>, is just enumerating after all. The same is true for a lot of Linq's functionality.

So let's take a look at the specific code in your question:

Predicate<int> pre = delegate(int a){ return a % 2 == 0; };

Here we have a Predicate<int> pre that takes an int a and returns a % 2 == 0. This is essentially testing for an even number. What that means is:

pre(1) == false;
pre(2) == true;

And so on. This also means, if you have a List<int> ints and you want to find the first even number, you can just do this:

int firstEven = ints.Find(pre);

Of course, as with any other type that you can use in code, it's a good idea to give your variables descriptive names; so I would advise changing the above pre to something like evenFinder or isEven -- something along those lines. Then the above code is a lot clearer:

int firstEven = ints.Find(evenFinder);

Assigning multiple styles on an HTML element

The way you have used the HTML syntax is problematic.

This is how the syntax should be


In your case, this will be the way to do

<h2 style="text-align :center; font-family :tahoma" >TITLE</h2>

A further example would be as follows

<div class ="row">
    <button type="button" style= "margin-top : 20px; border-radius: 15px" 
    class="btn btn-primary">View Full Profile</button>

SQLException: No suitable Driver Found for jdbc:oracle:thin:@//localhost:1521/orcl

First, if you develop an application with Java EE 6 within a server (JBoss), you should better use a DataSource. Then you can obtain the Connection from this DataSource. It's better to use connections pools.

Then, as of JBoss AS 7, the JDBC driver must be declared as a module. This is described here.

With OJDBC 6 (11.x), the name of the driver should be "oracle.jdbc.OracleDriver". This is the name registered in SPI mode (see the content of this file : META-INF/services/java.sql.Driver).
Since Java 6 and JDBC 4.0, the JDBC Drivers are auto-registered.

Finally you will have to declare a DataSource within JBoss : DataSource configuration.

References :

  • Establishing a Connection (link) (JDBC 4.0 <=> Java 6)
  • JDBC 4.0 Enhancements in Java SE 6 > Auto-Loading of JDBC Driver (link)

How to style a disabled checkbox?

This is supported by IE too:





Create stacked barplot where each stack is scaled to sum to 100%

Here's a solution using that ggplot package (version 3.x) in addition to what you've gotten so far.

We use the position argument of geom_bar set to position = "fill". You may also use position = position_fill() if you want to use the arguments of position_fill() (vjust and reverse).

Note that your data is in a 'wide' format, whereas ggplot2 requires it to be in a 'long' format. Thus, we first need to gather the data.


dat <- read.table(text = "    ONE TWO THREE
1   23  234 324
2   34  534 12
3   56  324 124
4   34  234 124
5   123 534 654",sep = "",header = TRUE)

# Add an id variable for the filled regions and reshape
datm <- dat %>% 
  mutate(ind = factor(row_number())) %>%  
  gather(variable, value, -ind)

ggplot(datm, aes(x = variable, y = value, fill = ind)) + 
    geom_bar(position = "fill",stat = "identity") +
    # or:
    # geom_bar(position = position_fill(), stat = "identity") 
    scale_y_continuous(labels = scales::percent_format())

example figure

How To Execute SSH Commands Via PHP

For those using the Symfony framework, the phpseclib can also be used to connect via SSH. It can be installed using composer:

composer require phpseclib/phpseclib

Next, simply use it as follows:

use phpseclib\Net\SSH2;

// Within a controller for example:
$ssh = new SSH2('hostname or ip');
if (!$ssh->login('username', 'password')) {
    // Login failed, do something

$return_value = $ssh->exec('command');

How does Content Security Policy (CSP) work?

The Content-Security-Policy meta-tag allows you to reduce the risk of XSS attacks by allowing you to define where resources can be loaded from, preventing browsers from loading data from any other locations. This makes it harder for an attacker to inject malicious code into your site.

I banged my head against a brick wall trying to figure out why I was getting CSP errors one after another, and there didn't seem to be any concise, clear instructions on just how does it work. So here's my attempt at explaining some points of CSP briefly, mostly concentrating on the things I found hard to solve.

For brevity I won’t write the full tag in each sample. Instead I'll only show the content property, so a sample that says content="default-src 'self'" means this:

<meta http-equiv="Content-Security-Policy" content="default-src 'self'">

1. How can I allow multiple sources?

You can simply list your sources after a directive as a space-separated list:

content="default-src 'self'"

Note that there are no quotes around parameters other than the special ones, like 'self'. Also, there's no colon (:) after the directive. Just the directive, then a space-separated list of parameters.

Everything below the specified parameters is implicitly allowed. That means that in the example above these would be valid sources:

These, however, would not be valid:
^^^^ wrong protocol
                   ^^ above the specified path

2. How can I use different directives? What do they each do?

The most common directives are:

  • default-src the default policy for loading javascript, images, CSS, fonts, AJAX requests, etc
  • script-src defines valid sources for javascript files
  • style-src defines valid sources for css files
  • img-src defines valid sources for images
  • connect-src defines valid targets for to XMLHttpRequest (AJAX), WebSockets or EventSource. If a connection attempt is made to a host that's not allowed here, the browser will emulate a 400 error

There are others, but these are the ones you're most likely to need.

3. How can I use multiple directives?

You define all your directives inside one meta-tag by terminating them with a semicolon (;):

content="default-src 'self'; style-src 'self'"

4. How can I handle ports?

Everything but the default ports needs to be allowed explicitly by adding the port number or an asterisk after the allowed domain:

content="default-src 'self'"

The above would result in:
                           ^^^^ Not ok, wrong port - OK
                 ^^ Not ok, only the port 123 is allowed - OK

As I mentioned, you can also use an asterisk to explicitly allow all ports:


5. How can I handle different protocols?

By default, only standard protocols are allowed. For example to allow WebSockets ws:// you will have to allow it explicitly:

content="default-src 'self'; connect-src ws:; style-src 'self'"
                                         ^^^ web Sockets are now allowed on all domains and ports.

6. How can I allow the file protocol file://?

If you'll try to define it as such it won’t work. Instead, you'll allow it with the filesystem parameter:

content="default-src filesystem"

7. How can I use inline scripts and style definitions?

Unless explicitly allowed, you can't use inline style definitions, code inside <script> tags or in tag properties like onclick. You allow them like so:

content="script-src 'unsafe-inline'; style-src 'unsafe-inline'"

You'll also have to explicitly allow inline, base64 encoded images:

content="img-src data:"

8. How can I allow eval()?

I'm sure many people would say that you don't, since 'eval is evil' and the most likely cause for the impending end of the world. Those people would be wrong. Sure, you can definitely punch major holes into your site's security with eval, but it has perfectly valid use cases. You just have to be smart about using it. You allow it like so:

content="script-src 'unsafe-eval'"

9. What exactly does 'self' mean?

You might take 'self' to mean localhost, local filesystem, or anything on the same host. It doesn't mean any of those. It means sources that have the same scheme (protocol), same host, and same port as the file the content policy is defined in. Serving your site over HTTP? No https for you then, unless you define it explicitly.

I've used 'self' in most examples as it usually makes sense to include it, but it's by no means mandatory. Leave it out if you don't need it.

But hang on a minute! Can't I just use content="default-src *" and be done with it?

No. In addition to the obvious security vulnerabilities, this also won’t work as you'd expect. Even though some docs claim it allows anything, that's not true. It doesn't allow inlining or evals, so to really, really make your site extra vulnerable, you would use this:

content="default-src * 'unsafe-inline' 'unsafe-eval'"

... but I trust you won’t.

Further reading:

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

If all hours must be displayed (more than 24) and if '0' before hours is not necessary, then formatting can be done with a short line of code:

Math.floor('h')) + moment.utc('ms')).format(':mm:ss')

How can you get the build/version number of your Android application?

Slightly shorter version if you just want the version name.

String versionName = context.getPackageManager()
    .getPackageInfo(context.getPackageName(), 0).versionName;

Python: No acceptable C compiler found in $PATH when installing python

On Arch Linux run the following:

sudo pacman -S base-devel

Vim delete blank lines

This function only remove two or more blank lines, put the lines below in your vimrc, then use \d to call function

fun! DelBlank()
   let _s=@/
   let l = line(".")
   let c = col(".")
   let @/=_s
   call cursor(l, c)
map <special> <leader>d :keepjumps call DelBlank()<cr>

Replace Div Content onclick

A simple addClass and removeClass will do the trick on what you need..

$('#change').on('click', function() { 
  $('div').each(function() { 
    if($(this).hasClass('active')) { 
    } else { 


Seee fiddle

I recommend you to learn jquery first before using.

How to calculate age (in years) based on Date of Birth and getDate()

Try This

DECLARE @date datetime, @tmpdate datetime, @years int, @months int, @days int
SELECT @date = '08/16/84'

SELECT @tmpdate = @date

SELECT @tmpdate = DATEADD(yy, @years, @tmpdate)
SELECT @months = DATEDIFF(m, @tmpdate, GETDATE()) - CASE WHEN DAY(@date) > DAY(GETDATE()) THEN 1 ELSE 0 END
SELECT @tmpdate = DATEADD(m, @months, @tmpdate)
SELECT @days = DATEDIFF(d, @tmpdate, GETDATE())

SELECT Convert(Varchar(Max),@years)+' Years '+ Convert(Varchar(max),@months) + ' Months '+Convert(Varchar(Max), @days)+'days'

Xcode 9 error: "iPhone has denied the launch request"

It may cause with switched a wrong branch with Git, Make sure the branch you switch not too old(since it may cause code sign issue), And on the right branch if this still bothering, select the development Provisioning Profile under Signing(Debug) if u r not Automatically manage siging.

"unmappable character for encoding" warning in Java

put this line in yor file .gradle above the Java conf.

apply plugin: 'java'
compileJava {options.encoding = "UTF-8"}   

Is the buildSessionFactory() Configuration method deprecated in Hibernate

I edited the method created by batbaatar above so it accepts the Configuration object as a parameter:

    public static SessionFactory createSessionFactory(Configuration configuration) {
        serviceRegistry = new StandardServiceRegistryBuilder().applySettings(
        factory = configuration.buildSessionFactory(serviceRegistry);
        return factory;

In the main class I did:

    private static SessionFactory factory;
    private static Configuration configuration 
    configuration = new Configuration();
    // Other configurations, then           
    factory = createSessionFactory(configuration);

How to get a file directory path from file path?

If you care target files to be symbolic link, firstly you can check it and get the original file. The if clause below may help you.

if [ -h $file ]
 base=$(dirname $(readlink $file))
 base=$(dirname $file)

how to convert 2d list to 2d numpy array?

just use following code

c = np.matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
matrix([[1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]])

Then it will give you

you can check shape and dimension of matrix by using following code



How to get name of dataframe column in pyspark?

I found the answer is very very simple...

// It is in java, but it should be same in pyspark
Column col = ds.col("colName"); //the column object
String theNameOftheCol = col.toString();

The variable "theNameOftheCol" is "colName"

HTML embedded PDF iframe


<iframe id="fred" style="border:1px solid #666CCC" title="PDF in an i-Frame" src="PDFData.pdf" frameborder="1" scrolling="auto" height="1100" width="850" ></iframe>


<object data="your_url_to_pdf" type="application/pdf">
  <embed src="your_url_to_pdf" type="application/pdf" />

SQL Server CTE and recursion example

    --DROP TABLE #Employee
    CREATE TABLE #Employee(EmpId BIGINT IDENTITY,EmpName VARCHAR(25),Designation VARCHAR(25),ManagerID BIGINT)

    INSERT INTO #Employee VALUES('M11M','Manager',NULL)
    INSERT INTO #Employee VALUES('P11P','Manager',NULL)

    INSERT INTO #Employee VALUES('AA','Clerk',1)
    INSERT INTO #Employee VALUES('AB','Assistant',1)
    INSERT INTO #Employee VALUES('ZC','Supervisor',2)
    INSERT INTO #Employee VALUES('ZD','Security',2)

    SELECT * FROM #Employee (NOLOCK)

    WITH Emp_CTE 
        SELECT EmpId,EmpName,Designation, ManagerID
              ,CASE WHEN ManagerID IS NULL THEN EmpId ELSE ManagerID END ManagerID_N
        FROM #Employee  
    select EmpId,EmpName,Designation, ManagerID
    FROM Emp_CTE
    order BY ManagerID_N, EmpId

How to remove MySQL completely with config and library files?

Just a little addition to the answer of @dAm2k :

In addition to sudo apt-get remove --purge mysql\*

I've done a sudo apt-get remove --purge mariadb\*.

I seems that in the new release of debian (stretch), when you install mysql it install mariadb package with it.

Hope it helps.

PHP Remove elements from associative array

$key = array_search("Mark As Spam", $array);

For 2D arrays...

$remove = array("Mark As Spam", "Completed");
foreach($arrays as $array){
    foreach($array as $key => $value){
        if(in_array($value, $remove)) unset($array[$key]);

How to Identify port number of SQL server

You can also use this query

USE MASTER GO xp_readerrorlog 0, 1, N'Server is listening on' GO

Source : sqlauthority blog

Git adding files to repo

After adding files to the stage, you need to commit them with git commit -m "comment" after git add .. Finally, to push them to a remote repository, you need to git push <remote_repo> <local_branch>.

Add a summary row with totals

Try to use union all as below

SELECT [Type], [Total Sales] From Before
union all
SELECT 'Total', Sum([Total Sales]) From Before

if you have problem with ordering, as i-one suggested try this:

select [Type], [Total Sales] 
from (SELECT [Type], [Total Sales], 0 [Key] 
      From Before 
      union all 
      SELECT 'Total', Sum([Total Sales]), 1 From Before) sq 
order by [Key], Type

Iterate over model instance field names and values in template

I'm using this,

    {% for column in table.columns %}
    <th><a href="?sort={{ column.name_toggled }}">{{ column }}</a></th>
    {% endfor %}
{% for row in table.rows %}
    {% for value in row %}
        <td>{{ value }}</td>
    {% endfor %}
{% endfor %}

Do on-demand Mac OS X cloud services exist, comparable to Amazon's EC2 on-demand instances?

Here are some methods that may help others, though they aren't really services as much as they may be described as "methods that may, after some torture of effort or logic, lead to a claim of on-demand access to Mac OS X" (no doubt I should patent that phrase).

Fundamentally, I am inclined to believe that on-demand (per-hour) hosting does not exist, and @Erik has given information for the shortest feasible services, i.e. monthly hosting.

It seems that one may use EC2 itself, but install OS X on the instance through a lot of elbow grease.

  • This article on gives instructions for setting up OSX under Virtual Box and depends on hardware virtualization. It seems that the Cluster Compute instances (and Cluster GPU, but ignore these) are the only ones supporting hardware virtualization.
  • This article gives instructions for transferring a VirtualBox image to EC2.

Where this gets tricky is I'm not sure if this will work for a cluster compute instance. In fact, I think this is likely to be a royal pain. A similar approach may work for Rackspace or other cloud services.

I found only this site claiming on-demand Mac hosting, with a Mac Mini. It doesn't look particularly accurate: it offers free on-demand access to a Mini if one pays for a month of bandwidth. That's like free bandwidth if one rents a Mini for a month. That's not really how "on-demand" works.

Update 1: In the end, it seems that nobody offers a comparable service. An outfit called Media Temple claims they will offer the first virtual servers using Parallels, OS X Leopard, and some other stuff (in other words, I wonder if there is some caveat that makes them unique, but, without that caveat, someone else may have a usable offering).

After this search, I think that a counterpart to EC2 does not exist for the OS X operating system. It is extraordinarily unlikely that one would exist, offer a scalable solution, and yet be very difficult to find. One could set it up internally, but there's no reseller/vendor offering on-demand, hourly virtual servers. This may be disappointing, but not surprising - apparently iCloud is running on Amazon and Microsoft systems.

how to display full stored procedure code?

Normally speaking you'd use a DB manager application like pgAdmin, browse to the object you're interested in, and right click your way to "script as create" or similar.

Are you trying to do this... without a management app?

How to get first record in each group using Linq

    var res = from element in list
              group element by element.F1
                  into groups
                  select groups.OrderBy(p => p.F2).First();

How to filter an array from all elements of another array

The solution of Jack Giffin is great but doesn't work for arrays with numbers bigger than 2^32. Below is a refactored, fast version to filter an array based on Jack's solution but it works for 64-bit arrays.

const Math_clz32 = Math.clz32 || ((log, LN2) => x => 31 - log(x >>> 0) / LN2 | 0)(Math.log, Math.LN2);

const filterArrayByAnotherArray = (searchArray, filterArray) => {

    searchArray.sort((a,b) => a > b);
    filterArray.sort((a,b) => a > b);

    let searchArrayLen = searchArray.length, filterArrayLen = filterArray.length;
    let progressiveLinearComplexity = ((searchArrayLen<<1) + filterArrayLen)>>>0
    let binarySearchComplexity = (searchArrayLen * (32-Math_clz32(filterArrayLen-1)))>>>0;

    let i = 0;

    if (progressiveLinearComplexity < binarySearchComplexity) {
      return searchArray.filter(currentValue => {
        while (filterArray[i] < currentValue) i=i+1|0;
        return filterArray[i] !== currentValue;
    else return searchArray.filter(e => binarySearch(filterArray, e) === null);

const binarySearch = (sortedArray, elToFind) => {
  let lowIndex = 0;
  let highIndex = sortedArray.length - 1;
  while (lowIndex <= highIndex) {
    let midIndex = Math.floor((lowIndex + highIndex) / 2);
    if (sortedArray[midIndex] == elToFind) return midIndex; 
    else if (sortedArray[midIndex] < elToFind) lowIndex = midIndex + 1;
    else highIndex = midIndex - 1;
  } return null;

Android soft keyboard covers EditText field

Are you asking how to control what is visible when the soft keyboard opens? You might want to play with the windowSoftInputMode. See developer docs for more discussion.

What is an Intent in Android?

An intent is an abstract description of an operation to be performed. It can be used with startActivity to launch an Activity, broadcastIntent to send it to any interested BroadcastReceiver components, and startService(Intent) or bindService(Intent, ServiceConnection, int) to communicate with a background Service.

For more details see these links :




there are many more articles are available.

How do I install SciPy on 64 bit Windows?

I found this solution after days.

Firstly, which Python version you want to install?

If you want for Python 2.7 version:






If you want for Python 3.4 version:





If you want for Python 3.5 version:





If you want for Python 3.6 version:





Link: click

Once finishing installation, go to your directory.

For example, my directory:

cd C:\Users\asus\AppData\Local\Programs\Python\Python35\Scripts>
pip install [where/is/your/downloaded/scipy_whl.]


NumPy + MKL

From same web site based on the Python version again:

After that use same thing again in the script folder:

cd C:\Users\asus\AppData\Local\Programs\Python\Python35\Scripts>

pip3 install [where/is/your/downloaded/numpy_whl.]

And test it in the Python folder.

Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:18:55) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import scipy

How to correctly dismiss a DialogFragment?

You should dismiss you Dialog in onPause() so override it.

Also before dismissing you can check for null and is showing like below snippet:

protected void onPause() {
    if (dialog != null && dialog.isShowing()) {

Why can't variables be declared in a switch statement?

Case statements are only labels. This means the compiler will interpret this as a jump directly to the label. In C++, the problem here is one of scope. Your curly brackets define the scope as everything inside the switch statement. This means that you are left with a scope where a jump will be performed further into the code skipping the initialization.

The correct way to handle this is to define a scope specific to that case statement and define your variable within it:

switch (val)
case VAL:  
  // This will work
  int newVal = 42;  

Iterating a JavaScript object's properties using jQuery

$.each( { name: "John", lang: "JS" }, function(i, n){
    alert( "Name: " + i + ", Value: " + n );


Parameter "stratify" from method "train_test_split" (scikit Learn)

In this context, stratification means that the train_test_split method returns training and test subsets that have the same proportions of class labels as the input dataset.

Save Dataframe to csv directly to s3 Python

You can also use the AWS Data Wrangler:

import awswrangler as wr

Note that it will handle multipart upload for you to make the upload faster.

Rails how to run rake task

Sometimes Your rake tasks doesn't get loaded in console, In that case you can try the following commands

require "rake"

What is the use of "assert"?

The goal of an assertion in Python is to inform developers about unrecoverable errors in a program.

Assertions are not intended to signal expected error conditions, like “file not found”, where a user can take corrective action (or just try again).

Another way to look at it is to say that assertions are internal self-checks in your code. They work by declaring some conditions as impossible in your code. If these conditions don’t hold that means there’s a bug in the program.

If your program is bug-free, these conditions will never occur. But if one of them does occur the program will crash with an assertion error telling you exactly which “impossible” condition was triggered. This makes it much easier to track down and fix bugs in your programs.

Here’s a summary from a tutorial on Python’s assertions I wrote:

Python’s assert statement is a debugging aid, not a mechanism for handling run-time errors. The goal of using assertions is to let developers find the likely root cause of a bug more quickly. An assertion error should never be raised unless there’s a bug in your program.

How to install pandas from pip on windows cmd?

If you are a windows user:
make sure you added the script(dir) path to environment variables
for more how to set path vist

How to wrap async function calls into a sync function in Node.js or Javascript?

I can't find a scenario that cannot be solved using node-fibers. The example you provided using node-fibers behaves as expected. The key is to run all the relevant code inside a fiber, so you don't have to start a new fiber in random positions.

Lets see an example: Say you use some framework, which is the entry point of your application (you cannot modify this framework). This framework loads nodejs modules as plugins, and calls some methods on the plugins. Lets say this framework only accepts synchronous functions, and does not use fibers by itself.

There is a library that you want to use in one of your plugins, but this library is async, and you don't want to modify it either.

The main thread cannot be yielded when no fiber is running, but you still can create plugins using fibers! Just create a wrapper entry that starts the whole framework inside a fiber, so you can yield the execution from the plugins.

Downside: If the framework uses setTimeout or Promises internally, then it will escape the fiber context. This can be worked around by mocking setTimeout, Promise.then, and all event handlers.

So this is how you can yield a fiber until a Promise is resolved. This code takes an async (Promise returning) function and resumes the fiber when the promise is resolved:




exports.getValueAsync = () => {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve("Async Value");
    }, 100);


const Fiber = require("fibers");

function fiberWaitFor(promiseOrValue) {
  var fiber = Fiber.current, error, value;
  Promise.resolve(promiseOrValue).then(v => {
    error = false;
    value = v;;
  }, e => {
    error = true;
    value = e;;
  if (error) {
    throw value;
  } else {
    return value;

const asyncLib = require("./async-lib"); = () => {
  return fiberWaitFor(asyncLib.getValueAsync());


require("fibers")(() => {

When you run node framework-entry.js it will throw an error: Error: yield() called with no fiber running. If you run node my-entry.js it works as expected.

What browsers support HTML5 WebSocket API?

Client side

  • Hixie-75:
    • Chrome 4.0 + 5.0
    • Safari 5.0.0
  • HyBi-00/Hixie-76:
  • HyBi-07+:
  • HyBi-10:
    • Chrome 14.0 + 15.0
    • Firefox 7.0 + 8.0 + 9.0 + 10.0 - prefixed: MozWebSocket
    • IE 10 (from Windows 8 developer preview)
  • HyBi-17/RFC 6455
    • Chrome 16
    • Firefox 11
    • Opera 12.10 / Opera Mobile 12.1

Any browser with Flash can support WebSocket using the web-socket-js shim/polyfill.

See caniuse for the current status of WebSockets support in desktop and mobile browsers.

See the test reports from the WS testsuite included in Autobahn WebSockets for feature/protocol conformance tests.

Server side

It depends on which language you use.

In Java/Java EE:

Some other Java implementations:

In C#:


In Python:

In C:

In Node.js:

  • : also has serverside ports for Python, Java, Google GO, Rack
  • sockjs : sockjs also has serverside ports for Python, Java, Erlang and Lua
  • WebSocket-Node - Pure JavaScript Client & Server implementation of HyBi-10.

Vert.x (also known as Node.x) : A node like polyglot implementation running on a Java 7 JVM and based on Netty with :

  • Support for Ruby(JRuby), Java, Groovy, Javascript(Rhino/Nashorn), Scala, ...
  • True threading. (unlike Node.js)
  • Understands multiple network protocols out of the box including: TCP, SSL, UDP, HTTP, HTTPS, Websockets, SockJS as fallback for WebSockets is a Websocket cloud service accessible through a REST API.

DotCloud cloud platform supports Websockets, and Java (Jetty Servlet Container), NodeJS, Python, Ruby, PHP and Perl programming languages.

Openshift cloud platform supports websockets, and Java (Jboss, Spring, Tomcat & Vertx), PHP (ZendServer & CodeIgniter), Ruby (ROR), Node.js, Python (Django & Flask) plateforms.

For other language implementations, see the Wikipedia article for more information.

The RFC for Websockets : RFC6455

setHintTextColor() in EditText

Seems that EditText apply the hintTextColor only if the text is empty. So simple solution will be like this

Editable text = mEditText.getText();

If you have multiple fields, you can extend the EditText and write a method which executes this logic and use that method instead.

What's the difference between size_t and int in C++?

size_t is the type used to represent sizes (as its names implies). Its platform (and even potentially implementation) dependent, and should be used only for this purpose. Obviously, representing a size, size_t is unsigned. Many stdlib functions, including malloc, sizeof and various string operation functions use size_t as a datatype.

An int is signed by default, and even though its size is also platform dependant, it will be a fixed 32bits on most modern machine (and though size_t is 64 bits on 64-bits architecture, int remain 32bits long on those architectures).

To summarize : use size_t to represent the size of an object and int (or long) in other cases.

LINQ Aggregate algorithm explained


Aggregate method is an extension method for generic collections. Aggregate method applies a function to each item of a collection. Not just only applies a function, but takes its result as initial value for the next iteration. So, as a result, we will get a computed value (min, max, avg, or other statistical value) from a collection.

Therefore, Aggregate method is a form of safe implementation of a recursive function.

Safe, because the recursion will iterate over each item of a collection and we can’t get any infinite loop suspension by wrong exit condition. Recursive, because the current function’s result is used as a parameter for the next function call.


collection.Aggregate(seed, func, resultSelector);
  • seed - initial value by default;
  • func - our recursive function. It can be a lambda-expression, a Func delegate or a function type T F(T result, T nextValue);
  • resultSelector - it can be a function like func or an expression to compute, transform, change, convert the final result.

How it works:

var nums = new[]{1, 2};
var result = nums.Aggregate(1, (result, n) => result + n); //result = (1 + 1) + 2 = 4
var result2 = nums.Aggregate(0, (result, n) => result + n, response => (decimal)response/2.0); //result2 = ((0 + 1) + 2)*1.0/2.0 = 3*1.0/2.0 = 3.0/2.0 = 1.5

Practical usage:

  1. Find Factorial from a number n:

int n = 7;
var numbers = Enumerable.Range(1, n);
var factorial = numbers.Aggregate((result, x) => result * x);

which is doing the same thing as this function:

public static int Factorial(int n)
   if (n < 1) return 1;

   return n * Factorial(n - 1);
  1. Aggregate() is one of the most powerful LINQ extension method, like Select() and Where(). We can use it to replace the Sum(), Min(). Max(), Avg() functionality, or to change it by implementing addition context:
    var numbers = new[]{3, 2, 6, 4, 9, 5, 7};
    var avg = numbers.Aggregate(0.0, (result, x) => result + x, response => (double)response/(double)numbers.Count());
    var min = numbers.Aggregate((result, x) => (result < x)? result: x);
  1. More complex usage of extension methods:
    var path = @“c:\path-to-folder”;

    string[] txtFiles = Directory.GetFiles(path).Where(f => f.EndsWith(“.txt”)).ToArray<string>();
    var output = txtFiles.Select(f => File.ReadAllText(f, Encoding.Default)).Aggregate<string>((result, content) => result + content);

    File.WriteAllText(path + “summary.txt”, output, Encoding.Default);

    Console.WriteLine(“Text files merged into: {0}”, output); //or other log info

Where can I get Google developer key

Update no 3:

You can get a Developer_Key from here Get your Google Developer Key

Check this tutorial

{select as answered, if it answered.}

Update no 2:

"API key" is the DEVELOPER_KEY

if you check this code reference, it states

Set DEVELOPER_KEY to the "API key" value from the "Access" tab of the Google APIs Console`

Wiki on step by step to get API Key & secret


Developer API Key! probably this is what you might be looking for


If say, for instance, you have a web app which would require a API key then check this:

  1. Go to Google API Console Select you project OR Create your project.
  2. Select APIs & Auths enter image description here
  3. API Project from the Dropdown on the left navigation panel
  4. API Access
  5. Click on Create another Client ID
  6. Select Service application refer it here

The Service application that you have created can be used by your Web apps such as PHP, Python, ..., etc. enter image description here

Check/Uncheck a checkbox on datagridview

Try the below code it should work

private void checkBox2_CheckedChanged(object sender, EventArgs e) 
    if (checkBox2.Checked == false)
        foreach (DataGridViewRow row in dGV1.Rows)
            DataGridViewCheckBoxCell chk = (DataGridViewCheckBoxCell)row.Cells[0];
            chk.Value = chk.TrueValue;
   else if (checkBox2.Checked == true)
        foreach (DataGridViewRow row in dGV1.Rows)
            DataGridViewCheckBoxCell chk = (DataGridViewCheckBoxCell)row.Cells[0];
            chk.Value = 1;
            if (row.IsNewRow)
                chk.Value = 0;

VBA using ubound on a multidimensional array

ubound(arr, 1) 


ubound(arr, 2) 

Android Studio: Gradle - build fails -- Execution failed for task ':dexDebug'

Could fix this by adding

compile ''

to the dependencies in the vertretungsplan build.gradle, compile and then remove this line and compile again.

now it works

My Routes are Returning a 404, How can I Fix Them?

Have you tried to check if


was working? If so then make sure all your path's folders don't have any uppercase letters. I had the same situation and converting letters to lower case helped.

ORDER BY date and time BEFORE GROUP BY name in mysql

This worked for me:

FROM your_table
    SELECT MAX(id)
    FROM your_table
    GROUP BY name

Where can I download Spring Framework jars without using Maven?

Please edit to keep this list of mirrors current

I found this maven repo where you could download from directly a zip file containing all the jars you need.

Alternate solution: Maven

The solution I prefer is using Maven, it is easy and you don't have to download each jar alone. You can do it with the following steps:

  1. Create an empty folder anywhere with any name you prefer, for example spring-source

  2. Create a new file named pom.xml

  3. Copy the xml below into this file

  4. Open the spring-source folder in your console

  5. Run mvn install

  6. After download finished, you'll find spring jars in /spring-source/target/dependencies

    <project xmlns="" xmlns:xsi="" xsi:schemaLocation="">

Also, if you need to download any other spring project, just copy the dependency configuration from its corresponding web page.

For example, if you want to download Spring Web Flow jars, go to its web page, and add its dependency configuration to the pom.xml dependencies, then run mvn install again.


Remove all newlines from inside a string

strip only removes characters from the beginning and end of a string. You want to use replace:

str2 = str.replace("\n", "")
re.sub('\s{2,}', ' ', str) # To remove more than one space 

Difference between final and effectively final

I find the simplest way to explain "effectively final" is to imagine adding the final modifier to a variable declaration. If, with this change, the program continues to behave in the same way, both at compile time and at run time, then that variable is effectively final.

Python calling method in class

Let's say you have a shiny Foo class. Well you have 3 options:

1) You want to use the method (or attribute) of a class inside the definition of that class:

class Foo(object):
    attribute1 = 1                   # class attribute (those don't use 'self' in declaration)
    def __init__(self):
        self.attribute2 = 2          # instance attribute (those are accessible via first
                                     # parameter of the method, usually called 'self'
                                     # which will contain nothing but the instance itself)
    def set_attribute3(self, value): 
        self.attribute3 = value

    def sum_1and2(self):
        return self.attribute1 + self.attribute2

2) You want to use the method (or attribute) of a class outside the definition of that class

def get_legendary_attribute1():
    return Foo.attribute1

def get_legendary_attribute2():
    return Foo.attribute2

def get_legendary_attribute1_from(cls):
    return cls.attribute1

get_legendary_attribute1()           # >>> 1
get_legendary_attribute2()           # >>> AttributeError: type object 'Foo' has no attribute 'attribute2'
get_legendary_attribute1_from(Foo)   # >>> 1

3) You want to use the method (or attribute) of an instantiated class:

f = Foo()
f.attribute1                         # >>> 1
f.attribute2                         # >>> 2
f.attribute3                         # >>> AttributeError: 'Foo' object has no attribute 'attribute3'
f.attribute3                         # >>> 3

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



// x86

// x64

Force "portrait" orientation mode

I think you want to add android:configChanges="orientation|keyboardHidden" to your activity? Otherwise the activity is restarted on config-change. The onConfigurationChanged would not be called then, only the onCreate

Escape string Python for MySQL

install sqlescapy package:

pip install sqlescapy

then you can escape variables in you raw query

from sqlescapy import sqlescape

query = """
    SELECT * FROM "bar_table" WHERE id='%s'
""" % sqlescape(user_input)

What are the differences and similarities between ffmpeg, libav, and avconv?

Confusing messages

These messages are rather misleading and understandably a source of confusion. Older Ubuntu versions used Libav which is a fork of the FFmpeg project. FFmpeg returned in Ubuntu 15.04 "Vivid Vervet".

The fork was basically a non-amicable result of conflicting personalities and development styles within the FFmpeg community. It is worth noting that the maintainer for Debian/Ubuntu switched from FFmpeg to Libav on his own accord due to being involved with the Libav fork.

The real ffmpeg vs the fake one

For a while both Libav and FFmpeg separately developed their own version of ffmpeg.

Libav then renamed their bizarro ffmpeg to avconv to distance themselves from the FFmpeg project. During the transition period the "not developed anymore" message was displayed to tell users to start using avconv instead of their counterfeit version of ffmpeg. This confused users into thinking that FFmpeg (the project) is dead, which is not true. A bad choice of words, but I can't imagine Libav not expecting such a response by general users.

This message was removed upstream when the fake "ffmpeg" was finally removed from the Libav source, but, depending on your version, it can still show up in Ubuntu because the Libav source Ubuntu uses is from the ffmpeg-to-avconv transition period.

In June 2012, the message was re-worded for the package libav - 4:0.8.3-0ubuntu0.12.04.1. Unfortunately the new "deprecated" message has caused additional user confusion.

Starting with Ubuntu 15.04 "Vivid Vervet", FFmpeg's ffmpeg is back in the repositories again.

libav vs Libav

To further complicate matters, Libav chose a name that was historically used by FFmpeg to refer to its libraries (libavcodec, libavformat, etc). For example the libav-user mailing list, for questions and discussions about using the FFmpeg libraries, is unrelated to the Libav project.

How to tell the difference

If you are using avconv then you are using Libav. If you are using ffmpeg you could be using FFmpeg or Libav. Refer to the first line in the console output to tell the difference: the copyright notice will either mention FFmpeg or Libav.

Secondly, the version numbering schemes differ. Each of the FFmpeg or Libav libraries contains a version.h header which shows a version number. FFmpeg will end in three digits, such as 57.67.100, and Libav will end in one digit such as 57.67.0. You can also view the library version numbers by running ffmpeg or avconv and viewing the console output.

If you want to use the real ffmpeg

Ubuntu 15.04 "Vivid Vervet" or newer

The real ffmpeg is in the repository, so you can install it with:

apt-get install ffmpeg

For older Ubuntu versions

Your options are:

These methods are non-intrusive, reversible, and will not interfere with the system or any repository packages.

Another possible option is to upgrade to Ubuntu 15.04 "Vivid Vervet" or newer and just use ffmpeg from the repository.

Also see

For an interesting blog article on the situation, as well as a discussion about the main technical differences between the projects, see The FFmpeg/Libav situation.

How to test my servlet using JUnit

You can do this using Mockito to have the mock return the correct params, verify they were indeed called (optionally specify number of times), write the 'result' and verify it's correct.

import static org.junit.Assert.*;
import static org.mockito.Mockito.*;
import javax.servlet.http.*;
import org.junit.Test;

public class TestMyServlet extends Mockito{

    public void testServlet() throws Exception {
        HttpServletRequest request = mock(HttpServletRequest.class);       
        HttpServletResponse response = mock(HttpServletResponse.class);    


        StringWriter stringWriter = new StringWriter();
        PrintWriter writer = new PrintWriter(stringWriter);

        new MyServlet().doPost(request, response);

        verify(request, atLeast(1)).getParameter("username"); // only if you want to verify username was called...
        writer.flush(); // it may not have been flushed yet...
        assertTrue(stringWriter.toString().contains("My expected string"));

Django return redirect() with parameters

url(r'element/update/(?P<pk>\d+)/$', 'element.views.element_update', name='element_update'),

from django.shortcuts import redirect
from .models import Element

def element_info(request):
    # ...
    element = Element.object.get(pk=1)
    return redirect('element_update',

def element_update(request, pk)
    # ...

How do I set browser width and height in Selenium WebDriver?

It's easy. Here is the full code.

from selenium import webdriver
driver = webdriver.Chrome()
driver.get("Your URL")
driver.set_window_size(480, 320)

Make sure chrome driver is in your system path.

how to transfer a file through SFTP in java?

Try this code.

public void send (String fileName) {
    String SFTPHOST = "host:IP";
    int SFTPPORT = 22;
    String SFTPUSER = "username";
    String SFTPPASS = "password";
    String SFTPWORKINGDIR = "file/to/transfer";

    Session session = null;
    Channel channel = null;
    ChannelSftp channelSftp = null;
    System.out.println("preparing the host information for sftp.");

    try {
        JSch jsch = new JSch();
        session = jsch.getSession(SFTPUSER, SFTPHOST, SFTPPORT);
        java.util.Properties config = new java.util.Properties();
        config.put("StrictHostKeyChecking", "no");
        System.out.println("Host connected.");
        channel = session.openChannel("sftp");
        System.out.println("sftp channel opened and connected.");
        channelSftp = (ChannelSftp) channel;;
        File f = new File(fileName);
        channelSftp.put(new FileInputStream(f), f.getName());"File transfered successfully to host.");
    } catch (Exception ex) {
        System.out.println("Exception found while tranfer the response.");
    } finally {
        System.out.println("sftp Channel exited.");
        System.out.println("Channel disconnected.");
        System.out.println("Host Session disconnected.");

MySQL, Concatenate two columns

$crud->set_relation('id','students','{first_name} {last_name}');
$crud->display_as('student_id','Students Name');

How to write data with FileOutputStream without losing old data?

Use the constructor for appending material to the file:

FileOutputStream(File file, boolean append)
Creates a file output stream to write to the file represented by the specified File object.

So to append to a file say "abc.txt" use

FileOutputStream fos=new FileOutputStream(new File("abc.txt"),true);

How can I get a resource content from a static context?

There is also another possibilty. I load OpenGl shaders from resources like this:

static private String vertexShaderCode;
static private String fragmentShaderCode;

static {
    vertexShaderCode = readResourceAsString("/res/raw/vertex_shader.glsl");
    fragmentShaderCode = readResourceAsString("/res/raw/fragment_shader.glsl");

private static String readResourceAsString(String path) {
    Exception innerException;
    Class<? extends FloorPlanRenderer> aClass = FloorPlanRenderer.class;
    InputStream inputStream = aClass.getResourceAsStream(path);

    byte[] bytes;
    try {
        bytes = new byte[inputStream.available()];;
        return new String(bytes);
    } catch (IOException e) {
        innerException = e;
    throw new RuntimeException("Cannot load shader code from resources.", innerException);

As you can see, you can access any resource in path /res/... Change aClass to your class. This also how I load resources in tests (androidTests)

How to set an image's width and height without stretching it?

#logo {
    width: 400px;
    height: 200px;

    /*Scale down will take the necessary specified space that is 400px x 200px without stretching the image*/

How to get the file ID so I can perform a download of a file from Google Drive API on Android?

Well the first option I could think of is that you could send a list request with search parameters for your file, like title="File_1.xml" and fileExtension="xml". It will either return an empty list of files (there isn't one matching the serach criteria), or return a list with at least one file. If it's only one - it's easy. But if there are more - you'll have to select one of them based on some other fields. Remember that in gdrive you could have more than 1 file with the same name. So the more search parameters you provide, the better.

How to kill a process running on particular port in Linux?

One liner

kill -9 $(lsof -t -i tcp:8080)

explanation here: use a combination of lsof and kill

root@localhost:~# lsof -i tcp:8080
java    23672 sine  238u  IPv6 3028222      0t0  TCP localhost:http-alt (LISTEN)

select pid and use kill

kill 23672

Foreign Key to multiple tables

You have a few options, all varying in "correctness" and ease of use. As always, the right design depends on your needs.

  • You could simply create two columns in Ticket, OwnedByUserId and OwnedByGroupId, and have nullable Foreign Keys to each table.

  • You could create M:M reference tables enabling both ticket:user and ticket:group relationships. Perhaps in future you will want to allow a single ticket to be owned by multiple users or groups? This design does not enforce that a ticket must be owned by a single entity only.

  • You could create a default group for every user and have tickets simply owned by either a true Group or a User's default Group.

  • Or (my choice) model an entity that acts as a base for both Users and Groups, and have tickets owned by that entity.

Heres a rough example using your posted schema:

create table dbo.PartyType
    PartyTypeId tinyint primary key,
    PartyTypeName varchar(10)

insert into dbo.PartyType
    values(1, 'User'), (2, 'Group');

create table dbo.Party
    PartyId int identity(1,1) primary key,
    PartyTypeId tinyint references dbo.PartyType(PartyTypeId),
    unique (PartyId, PartyTypeId)

CREATE TABLE dbo.[Group]
    ID int primary key,
    Name varchar(50) NOT NULL,
    PartyTypeId as cast(2 as tinyint) persisted,
    foreign key (ID, PartyTypeId) references Party(PartyId, PartyTypeID)

    ID int primary key,
    Name varchar(50) NOT NULL,
    PartyTypeId as cast(1 as tinyint) persisted,
    foreign key (ID, PartyTypeId) references Party(PartyID, PartyTypeID)

    ID int primary key,
    [Owner] int NOT NULL references dbo.Party(PartyId),
    [Subject] varchar(50) NULL

The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value

In my case, in the initializer from the class I was using in the database's table, I wasn't setting any default value to my DateTime property, therefore resulting in the problem explained in @Andrew Orsich' answer. So I just made the property nullable. Or I could also have given it DateTime.Now in the constructor. Hope it helps someone.

How do I set the default Java installation/runtime (Windows)?

I simply install all the versions of JDK I need and the latest installed becomes default, so I just reinstall the one I want to be default if necessary.

Difference of two date time in sql server

PRINT DATEDIFF(second,'2010-01-22 15:29:55.090','2010-01-22 15:30:09.153')

What is the difference between application server and web server?

As many have said before, web servers handle HTTP petitions, while application servers handle petitions for distributed components. So, maybe the easiest way to understand the difference is to compare the two products in regards to programming environment they offer.

Web Server -> Programming Environment


Tomcat : Servlet

Jetty : Servlet

Apache : Php, CGI

Application Servers -> Programming Environment



JBoss : EJB

WebLogic Application Server : EJB

The crucial difference is that application servers support some distributed component technology, providing features like remote invocation and distributed transactions, like EJB in Java world or COM+ on Microsoft platform. Http server often support some more simple programming environments, often scripting, like ASP (.NET) in case of Microsoft or Servlet--based, including JSP and many other in case of Java or PHP and CGI in case of Apache.

Other capabilities like load-balancing, clustering, session-failover, connection pooling etc. that used to be in the realm of application servers, are becoming available on web servers as well directly or through some third party products.

Finally, it is worth noting that the picture is further distorted with "lightweight containers" like Spring Framework, that often supplement the purpose of application servers in more simple manner and without the application server infrastructure. And since distribution aspect in applications is moving from distributed component towards service paradigm and SOA architecture, there is less and less space left for traditional application servers.

ICommand MVVM implementation

This is almost identical to how Karl Shifflet demonstrated a RelayCommand, where Execute fires a predetermined Action<T>. A top-notch solution, if you ask me.

public class RelayCommand : ICommand
    private readonly Predicate<object> _canExecute;
    private readonly Action<object> _execute;

    public RelayCommand(Predicate<object> canExecute, Action<object> execute)
        _canExecute = canExecute;
        _execute = execute;

    public event EventHandler CanExecuteChanged
        add => CommandManager.RequerySuggested += value;
        remove => CommandManager.RequerySuggested -= value;

    public bool CanExecute(object parameter)
        return _canExecute(parameter);

    public void Execute(object parameter)

This could then be used as...

public class MyViewModel
    private ICommand _doSomething;
    public ICommand DoSomethingCommand
            if (_doSomething == null)
                _doSomething = new RelayCommand(
                    p => this.CanDoSomething,
                    p => this.DoSomeImportantMethod());
            return _doSomething;

Read more:
Josh Smith (introducer of RelayCommand): Patterns - WPF Apps With The MVVM Design Pattern

Should a function have only one return statement?

You should never use a return statement in a method.

I know I will be jumped on for this, but I am serious.

Return statements are basically a hangover from the procedural programming days. They are a form of goto, along with break, continue, if, switch/case, while, for, yield and some other statements and the equivalents in most modern programming languages.

Return statements effectively 'GOTO' the point where the function was called, assigning a variable in that scope.

Return statements are what I call a 'Convenient Nightmare'. They seem to get things done quickly, but cause massive maintenance headaches down the line.

Return statements are diametrically opposed to Encapsulation

This is the most important and fundamental concept of object oriented programming. It is the raison d'etre of OOP.

Whenever you return anything from a method, you are basically 'leaking' state information from the object. It doesn't matter if your state has changed or not, nor whether this information comes from other objects - it makes no difference to the caller. What this does is allow an object's behaviour to be outside of the object - breaking encapsulation. It allows the caller to start manipulating the object in ways that lead to fragile designs.

LoD is your friend

I recommend any developer to read about the Law of Demeter (LoD) on or Wikipedia. LoD is a design philosophy that has been used at places that have real 'mission-critical' software constraints in the literal sense, like the JPL. It has been shown to reduce the amount of bugs in code and improve flexibility.

There has an excellent analogy based on walking a dog. When you walk a dog, you do not physically grab hold of its legs and move them such that the dog walks. You command the dog to walk and it takes care of it's own legs. A return statement in this analogy is equivalent to the dog letting you grab hold of its legs.

Only talk to your immediate friends:

  1. arguments of the function you are in,
  2. your own attributes,
  3. any objects you created within the function

You will notice that none of these require a return statement. You might think the constructor is a return, and you are on to something. Actually the return is from the memory allocator. The constructor just sets what is in the memory. This is OK so long as the encapsulation of that new object is OK, because, as you made it, you have full control over it - no-one else can break it.

Accessing attributes of other objects is right out. Getters are out (but you knew they were bad already, right?). Setters are OK, but it is better to use constructors. Inheritance is bad - when you inherit from another class, any changes in that class can and probably will break you. Type sniffing is bad (Yes - LoD implies that Java/C++ style type based dispatch is incorrect - asking about type, even implicitly, is breaking encapsulation. Type is an implicit attribute of an object. Interfaces are The Right Thing).

So why is this all a problem? Well, unless your universe is very different from mine, you spend a lot of time debugging code. You aren't writing code that you plan never to reuse. Your software requirements are changing, and that causes internal API/interface changes. Every time you have used a return statement you have introduced a very tricky dependency - methods returning anything are required to know about how whatever they return is going to be used - that is each and every case! As soon as the interface changes, on one end or the other, everything can break, and you are faced with a lengthy and tedious bug hunt.

They really are an malignant cancer in your code, because once you start using them, they promote further use elsewhere (which is why you can often find returning method-chains amongst object systems).

So what is the alternative?

Tell, don't ask.

With OOP - the goal is to tell other objects what to do, and let them take care of it. So you have to forget the procedural ways of doing things. It's easy really - just never write return statements. There are much better ways of doing the same things:

There is nothing wrong with the return concept, but return statements are deeply flawed.

If you really need an answer back - use a call back. Pass in a data structure to be filled in, even. That way you keep the interfaces clean and open to change, and your whole system is less fragile and more adaptable. It does not slow your system down, in fact it can speed it up, in the same way as tail call optimisation does - except in this case, there is no tail call so you don't even have to waste time manipulating the stack with return values.

If you follow these arguments, you will find there really is never a need for a return statement.

If you follow these practices, I guarantee that pretty soon you will find that you are spending a lot less time hunting bugs, are adapting to requirement changes much more quickly, and having less problems understanding your own code.

Only allow specific characters in textbox

For your validation event IMO the easiest method would be to use a character array to validate textbox characters against. True - iterating and validating isn't particularly efficient, but it is straightforward.

Alternately, use a regular expression of your whitelist characters against the input string. Your events are availalbe at MSDN here:

Double % formatting question for printf in Java

Yes, %d means decimal, but it means decimal number system, not decimal point.

Further, as a complement to the former post, you can also control the number of decimal points to show. Try this,

System.out.printf("%.2f %.1f",d,f); // prints 1.20 1.2

For more please refer to the API docs.

PHP Convert String into Float/Double

Surprisingly there is no accepted answer. The issue only exists in 32-bit PHP.

From the documentation,

If the string does not contain any of the characters '.', 'e', or 'E' and the numeric value fits into integer type limits (as defined by PHP_INT_MAX), the string will be evaluated as an integer. In all other cases it will be evaluated as a float.

In other words, the $string is first interpreted as INT, which cause overflow (The $string value 2968789218 exceeds the maximum value (PHP_INT_MAX) of 32-bit PHP, which is 2147483647.), then evaluated to float by (float) or floatval().

Thus, the solution is:

$string = "2968789218";
echo 'Original: ' . floatval($string) . PHP_EOL;
$string.= ".0";
$float = floatval($string);
echo 'Corrected: ' . $float . PHP_EOL;

which outputs:

Original: 2.00
Corrected: 2968789218

To check whether your PHP is 32-bit or 64-bit, you can:


If your PHP is 64-bit, it will print out 9223372036854775807, otherwise it will print out 2147483647.

Using Mockito, how do I verify a method was a called with a certain argument?

First you need to create a mock m_contractsDao and set it up. Assuming that the class is ContractsDao:

ContractsDao mock_contractsDao = mock(ContractsDao.class);
when("Some result");

Then inject the mock into m_orderSvc and call your method.

m_orderSvc.m_contractsDao = mock_contractsDao;
m_prog = new ProcessOrdersWorker(m_orderSvc, m_opportunitySvc, m_myprojectOrgSvc);; 

Finally, verify that the mock was called properly:

verify(mock_contractsDao, times(1)).save("Parameter I'm expecting");

No shadow by default on Toolbar?

Google released the Design Support library a few weeks ago and there is a nifty solution for this problem in this library.

Add the Design Support library as a dependency in build.gradle :

compile ''

Add AppBarLayout supplied by the library as a wrapper around your Toolbar layout to generate a drop shadow.


Here is the result :

enter image description here

There are lots of other tricks with the design support library.



As above but with dependency:

implementation ''


How can I get a favicon to show up in my django app?

        <link rel="shortcut icon" type="image/png" href="{% static 'favicon/sample.png' %}" />

Also run: python collectstatic

Mix Razor and Javascript code

Inside a code block (eg, @foreach), you need to mark the markup (or, in this case, Javascript) with @: or the <text> tag.

Inside the markup contexts, you need to surround code with code blocks (@{ ... } or @if, ...)