Programs & Examples On #Java

Java (not to be confused with JavaScript or JScript or JS) is a general-purpose object-oriented programming language designed to be used in conjunction with the Java Virtual Machine (JVM). "Java platform" is the name for a computing system that has installed tools for developing and running Java programs. Use this tag for questions referring to the Java programming language or Java platform tools. not found error

here is your answer

String userName = "xxxx";
    String password = "xxxx";
    String url = ";databaseName=asdfzxcvqwer;integratedSecurity=true";

    try {
            connection = DriverManager.getConnection(url, userName, password); 

  } catch (Exception e)

Java OCR implementation

I recommend trying the Java OCR project on I originally developed it, and I have a blog posting on it.

Since I put it up on sourceforge, its functionality been expanded and improved quite a bit through the great work of a volunteer researcher/developer.

Give it a try, and if you don't like it, you can always improve it!

Reading a JSP variable from JavaScript

   <% String s="Hi"; %>
   var v ="<%=s%>"; 

Date in to UTC format Java

What Time Zones?

No where in your question do you mention time zone. What time zone is implied that input string? What time zone do you want for your output? And, UTC is a time zone (or lack thereof depending on your mindset) not a string format.

ISO 8601

Your input string is in ISO 8601 format, except that it lacks an offset from UTC.


Here is some example code in Joda-Time 2.3 to show you how to handle time zones. Joda-Time has built-in default formatters for parsing and generating String representations of date-time values.

String input = "2013-10-22T01:37:56";
DateTime dateTimeUtc = new DateTime( input, DateTimeZone.UTC );
DateTime dateTimeMontréal = dateTimeUtc.withZone( DateTimeZone.forID( "America/Montreal" );
String output = dateTimeMontréal.toString();

As for generating string representations in other formats, search StackOverflow for "Joda format".

Maven dependency update on commandline

mvn -Dschemaname=public liquibase:update

Execute method on startup in Spring

You can use @EventListener on your component, which will be invoked after the server is started and all beans initialized.

public void onApplicationEvent(ContextClosedEvent event) {


How Long Does it Take to Learn Java for a Complete Newbie?

10 weeks? Are you crazy? the Java API is massive not to mention Java EE how could possibly get through that in 10 weeks? you could maybe get through 5% of that in a couple of months. I'd say it would take at least a year to lean Java fundamentals for a newbie. I mean you can't just read a chapter on a subject and then think you understand it. You have to spend a good deal of time using that concept or part the API to at least commit it to memory never mind actually have a good grasp of it.

Realistically I'd say at least 2 maybe three years of programming to reach industry entry level standard. And that's if you really apply yourself.

Creating a mock HttpServletRequest out of a url string?

Simplest ways to mock an HttpServletRequest:

  1. Create an anonymous subclass:

    HttpServletRequest mock = new HttpServletRequest ()
        private final Map<String, String[]> params = /* whatever */
        public Map<String, String[]> getParameterMap()
            return params;
        public String getParameter(String name)
            String[] matches = params.get(name);
            if (matches == null || matches.length == 0) return null;
            return matches[0];
        // TODO *many* methods to implement here
  2. Use jMock, Mockito, or some other general-purpose mocking framework:

    HttpServletRequest mock = context.mock(HttpServletRequest.class); // jMock
    HttpServletRequest mock2 = Mockito.mock(HttpServletRequest.class); // Mockito
  3. Use HttpUnit's ServletUnit and don't mock the request at all.

Change icons of checked and unchecked for Checkbox for Android

I realize this is an old question, and the OP is talking about using custom gx that aren't necessary 'checkbox'-looking, but there is a fantastic resource for generating custom colored assets here:

Just give it the relevant details and it spits out graphics, complete with xml resources, that you can just drop right in.

Why am I not getting a java.util.ConcurrentModificationException in this example?

If you use copy-on-write collections it will work; however when you use list.iterator(), the returned Iterator will always reference the collection of elements as it was when ( as below ) list.iterator() was called, even if another thread modifies the collection. Any mutating methods called on a copy-on-write–based Iterator or ListIterator (such as add, set, or remove) will throw an UnsupportedOperationException.

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

public class RemoveListElementDemo {    
    private static final List<Integer> integerList;

    static {
        integerList = new CopyOnWriteArrayList<>();

    public static void remove(Integer remove) {
        for(Integer integer : integerList) {
            if(integer.equals(remove)) {                

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

        Integer remove = Integer.valueOf(3);
        for(Integer integer : integerList) {
            if(integer.equals(remove)) {                

Java - removing first character of a string

public String removeFirst(String input)
    return input.substring(1);

Cannot get a text value from a numeric cell “Poi”

As explained in the Apache POI Javadocs, you should not use cell.setCellType(Cell.CELL_TYPE_STRING) to get the string value of a numeric cell, as you'll loose all the formatting

Instead, as the javadocs explain, you should use DataFormatter

What DataFormatter does is take the floating point value representing the cell is stored in the file, along with the formatting rules applied to it, and returns you a string that look like it the cell does in Excel.

So, if you're after a String of the cell, looking much as you had it looking in Excel, just do:

 // Create a formatter, do this once
 DataFormatter formatter = new DataFormatter(Locale.US);


 for (int i=1; i <= sheet.getLastRowNum(); i++) {
        Row r = sheet.getRow(i);
        if (r == null) { 
           // empty row, skip
        } else {
           String j_username = formatter.formatCellValue(row.getCell(0));
           String j_password =  formatter.formatCellValue(row.getCell(1));

           // Use these

The formatter will return String cells as-is, and for Numeric cells will apply the formatting rules on the style to the number of the cell

How do I assert equality on two classes without an equals method?

AssertJ assertions can be used to compare the values without #equals method properly overridden, e.g.:

import static org.assertj.core.api.Assertions.assertThat; 

// ...


How to create a file in a directory in java?

With Java 7, you can use Path, Paths, and Files:

import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class CreateFile {

    public static void main(String[] args) throws IOException {
        Path path = Paths.get("/tmp/foo/bar.txt");


        try {
        } catch (FileAlreadyExistsException e) {
            System.err.println("already exists: " + e.getMessage());

Volatile Vs Atomic

There are two important concepts in multithreading environment:

  1. atomicity
  2. visibility

The volatile keyword eradicates visibility problems, but it does not deal with atomicity. volatile will prevent the compiler from reordering instructions which involve a write and a subsequent read of a volatile variable; e.g. k++. Here, k++ is not a single machine instruction, but three:

  1. copy the value to a register;
  2. increment the value;
  3. place it back.

So, even if you declare a variable as volatile, this will not make this operation atomic; this means another thread can see a intermediate result which is a stale or unwanted value for the other thread.

On the other hand, AtomicInteger, AtomicReference are based on the Compare and swap instruction. CAS has three operands: a memory location V on which to operate, the expected old value A, and the new value B. CAS atomically updates V to the new value B, but only if the value in V matches the expected old value A; otherwise, it does nothing. In either case, it returns the value currently in V. The compareAndSet() methods of AtomicInteger and AtomicReference take advantage of this functionality, if it is supported by the underlying processor; if it is not, then the JVM implements it via spin lock.

How can I slice an ArrayList out of an ArrayList in Java?

This is how I solved it. I forgot that sublist was a direct reference to the elements in the original list, so it makes sense why it wouldn't work.

ArrayList<Integer> inputA = new ArrayList<Integer>(input.subList(0, input.size()/2));

Java IOException "Too many open files"

You're obviously not closing your file descriptors before opening new ones. Are you on windows or linux?

builder for HashMap

You can use:

HashMap<String,Integer> m = Maps.newHashMap(

It's not as classy and readable, but does the work.

Get first date of current month in java

You can use withDayOfMonth(int dayOfMonth) method from java8 to return first day of month:

LocalDate firstDay =;
System.out.println(firstDay);   // 2019-09-01

Reversing a String with Recursion in Java

Run the code below - it prints:

Step 0: ello / H
Step 1: llo / e
Step 2: lo / l
Step 3: o / l
Step 3 returns: ol
Step 2 returns: oll
Step 1 returns: olle
Step 0 returns: olleH


public class Test {

    private static int i = 0;

    public static void main(String args[]) {

    public static String reverse(String str) {
        int localI = i++;
        if ((null == str) || (str.length()  <= 1)) {
            return str;
        System.out.println("Step " + localI + ": " + str.substring(1) + " / " + str.charAt(0));
        String reversed = reverse(str.substring(1)) + str.charAt(0);

        System.out.println("Step " + localI + " returns: " + reversed);
        return reversed;

What is the Simplest Way to Reverse an ArrayList?

Reversing a ArrayList in a recursive way and without creating a new list for adding elements :

   public class ListUtil {

    public static void main(String[] args) {
        ArrayList<String> arrayList = new ArrayList<String>();
        System.out.println("Reverse Order: " + reverse(arrayList));


    public static <T> List<T> reverse(List<T> arrayList) {
        return reverse(arrayList,0,arrayList.size()-1);
    public static <T> List<T> reverse(List<T> arrayList,int startIndex,int lastIndex) {

        if(startIndex<lastIndex) {
            T t=arrayList.get(lastIndex);
        return arrayList;


Check whether a string is not null and not empty

How about:

if(str!= null && str.length() != 0 )

how can I debug a jar at runtime?

Even though it is a runnable jar, you can still run it from a console -- open a terminal window, navigate to the directory containing the jar, and enter "java -jar yourJar.jar". It will run in that terminal window, and sysout and syserr output will appear there, including stack traces from uncaught exceptions. Be sure to have your debug set to true when you compile. And good luck.

Just thought of something else -- if you're on Win7, it often has permission problems with user applications writing files to specific directories. Make sure the directory to which you are writing your output file is one for which you have permissions.

In a future project, if it's big enough, you can use one of the standard logging facilities for 'debug' output; then it will be easy(ier) to redirect it to a file instead of depending on having a console. But for a smaller job like this, this should be fine.

Mvn install or Mvn package

If you're not using a remote repository (like artifactory), use plain old: mvn clean install

Pretty old topic but AFAIK, if you run your own repository (eg: with artifactory) to share jar among your team(s), you might want to use

mvn clean deploy


This way, your continuous integration server can be sure that all dependencies are correctly pushed into your remote repository. If you missed one, mvn will not be able to find it into your CI local m2 repository.

Creating a new ArrayList in Java

Java 8

In order to create a non-empty list of fixed size where different operations like add, remove, etc won't be supported:

List<Integer> fixesSizeList= Arrays.asList(1, 2);

Non-empty mutable list:

List<Integer> mutableList = new ArrayList<>(Arrays.asList(3, 4));

Java 9

With Java 9 you can use the List.of(...) static factory method:

List<Integer> immutableList = List.of(1, 2);

List<Integer> mutableList = new ArrayList<>(List.of(3, 4));

Java 10

With Java 10 you can use the Local Variable Type Inference:

var list1 = List.of(1, 2);

var list2 = new ArrayList<>(List.of(3, 4));

var list3 = new ArrayList<String>();

Check out more ArrayList examples here.

Java equivalent to C# extension methods

Technically C# Extension have no equivalent in Java. But if you do want to implement such functions for a cleaner code and maintainability, you have to use Manifold framework.


import manifold.ext.api.*;

public class MyStringExtension {

  public static void print(@This String thiz) {

  public static String lineSeparator() {
    return System.lineSeparator();

Utils to read resource text file to String (Java)

Use Apache commons's FileUtils. It has a method readFileToString

Where does the slf4j log file get saved?

It does not write to a file by default. You would need to configure something like the RollingFileAppender and have the root logger write to it (possibly in addition to the default ConsoleAppender).

Encoding URL query parameters in Java

if you have only space problem in url. I have used below code and it work fine

String url;
URL myUrl = new URL(url.replace(" ","%20"));

example : url is sir

then output of muUrl is

Byte and char conversion in Java

A character in Java is a Unicode code-unit which is treated as an unsigned number. So if you perform c = (char)b the value you get is 2^16 - 56 or 65536 - 56.

Or more precisely, the byte is first converted to a signed integer with the value 0xFFFFFFC8 using sign extension in a widening conversion. This in turn is then narrowed down to 0xFFC8 when casting to a char, which translates to the positive number 65480.

From the language specification:

5.1.4. Widening and Narrowing Primitive Conversion

First, the byte is converted to an int via widening primitive conversion (§5.1.2), and then the resulting int is converted to a char by narrowing primitive conversion (§5.1.3).

To get the right point use char c = (char) (b & 0xFF) which first converts the byte value of b to the positive integer 200 by using a mask, zeroing the top 24 bits after conversion: 0xFFFFFFC8 becomes 0x000000C8 or the positive number 200 in decimals.

Above is a direct explanation of what happens during conversion between the byte, int and char primitive types.

If you want to encode/decode characters from bytes, use Charset, CharsetEncoder, CharsetDecoder or one of the convenience methods such as new String(byte[] bytes, Charset charset) or String#toBytes(Charset charset). You can get the character set (such as UTF-8 or Windows-1252) from StandardCharsets.

Spring @Transactional - isolation, propagation

Transaction Isolation and Transaction Propagation although related but are clearly two very different concepts. In both cases defaults are customized at client boundary component either by using Declarative transaction management or Programmatic transaction management. Details of each isolation levels and propagation attributes can be found in reference links below.

Transaction Isolation

For given two or more running transactions/connections to a database, how and when are changes made by queries in one transaction impact/visible to the queries in a different transaction. It also related to what kind of database record locking will be used to isolate changes in this transaction from other transactions and vice versa. This is typically implemented by database/resource that is participating in transaction.


Transaction Propagation

In an enterprise application for any given request/processing there are many components that are involved to get the job done. Some of this components mark the boundaries (start/end) of a transaction that will be used in respective component and it's sub components. For this transactional boundary of components, Transaction Propogation specifies if respective component will or will not participate in transaction and what happens if calling component already has or does not have a transaction already created/started. This is same as Java EE Transaction Attributes. This is typically implemented by the client transaction/connection manager.


How to handle calendar TimeZones using Java?

Thank you all for responding. After a further investigation I got to the right answer. As mentioned by Skip Head, the TimeStamped I was getting from my application was being adjusted to the user's TimeZone. So if the User entered 6:12 PM (EST) I would get 2:12 PM (GMT). What I needed was a way to undo the conversion so that the time entered by the user is the time I sent to the WebServer request. Here's how I accomplished this:

// Get TimeZone of user
TimeZone currentTimeZone = sc_.getTimeZone();
Calendar currentDt = new GregorianCalendar(currentTimeZone, EN_US_LOCALE);
// Get the Offset from GMT taking DST into account
int gmtOffset = currentTimeZone.getOffset(
// convert to hours
gmtOffset = gmtOffset / (60*60*1000);
System.out.println("Current User's TimeZone: " + currentTimeZone.getID());
System.out.println("Current Offset from GMT (in hrs):" + gmtOffset);
// Get TS from User Input
Timestamp issuedDate = (Timestamp) getACPValue(inputs_, "issuedDate");
System.out.println("TS from ACP: " + issuedDate);
// Set TS into Calendar
Calendar issueDate = convertTimestampToJavaCalendar(issuedDate);
// Adjust for GMT (note the offset negation)
issueDate.add(Calendar.HOUR_OF_DAY, -gmtOffset);
System.out.println("Calendar Date converted from TS using GMT and US_EN Locale: "
    + DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT)

The code's output is: (User entered 5/1/2008 6:12PM (EST)

Current User's TimeZone: EST
Current Offset from GMT (in hrs):-4 (Normally -5, except is DST adjusted)
TS from ACP: 2008-05-01 14:12:00.0
Calendar Date converted from TS using GMT and US_EN Locale: 5/1/08 6:12 PM (GMT)

Java - How do I make a String array with values?

You want to initialize an array. (For more info - Tutorial)

int []ar={11,22,33};

String []stringAr={"One","Two","Three"};

From the JLS

The [] may appear as part of the type at the beginning of the declaration, or as part of the declarator for a particular variable, or both, as in this example:

byte[] rowvector, colvector, matrix[];

This declaration is equivalent to:

byte rowvector[], colvector[], matrix[][];

HashMap to return default value for non-found keys?

Java 8 introduced a nice computeIfAbsent default method to Map interface which stores lazy-computed value and so doesn't break map contract:

Map<Key, Graph> map = new HashMap<>();
map.computeIfAbsent(aKey, key -> createExpensiveGraph(key));


Disclamer: This answer doesn't match exactly what OP asked but may be handy in some cases matching question's title when keys number is limited and caching of different values would be profitable. It shouldn't be used in opposite case with plenty of keys and same default value as this would needlessly waste memory.

Comparing two maps

Quick Answer

You should use the equals method since this is implemented to perform the comparison you want. toString() itself uses an iterator just like equals but it is a more inefficient approach. Additionally, as @Teepeemm pointed out, toString is affected by order of elements (basically iterator return order) hence is not guaranteed to provide the same output for 2 different maps (especially if we compare two different maps).

Note/Warning: Your question and my answer assume that classes implementing the map interface respect expected toString and equals behavior. The default java classes do so, but a custom map class needs to be examined to verify expected behavior.


boolean equals(Object o)

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This ensures that the equals method works properly across different implementations of the Map interface.

Implementation in Java Source (java.util.AbstractMap)

Additionally, java itself takes care of iterating through all elements and making the comparison so you don't have to. Have a look at the implementation of AbstractMap which is used by classes such as HashMap:

 // Comparison and hashing

     * Compares the specified object with this map for equality.  Returns
     * <tt>true</tt> if the given object is also a map and the two maps
     * represent the same mappings.  More formally, two maps <tt>m1</tt> and
     * <tt>m2</tt> represent the same mappings if
     * <tt>m1.entrySet().equals(m2.entrySet())</tt>.  This ensures that the
     * <tt>equals</tt> method works properly across different implementations
     * of the <tt>Map</tt> interface.
     * <p>This implementation first checks if the specified object is this map;
     * if so it returns <tt>true</tt>.  Then, it checks if the specified
     * object is a map whose size is identical to the size of this map; if
     * not, it returns <tt>false</tt>.  If so, it iterates over this map's
     * <tt>entrySet</tt> collection, and checks that the specified map
     * contains each mapping that this map contains.  If the specified map
     * fails to contain such a mapping, <tt>false</tt> is returned.  If the
     * iteration completes, <tt>true</tt> is returned.
     * @param o object to be compared for equality with this map
     * @return <tt>true</tt> if the specified object is equal to this map
    public boolean equals(Object o) {
        if (o == this)
            return true;

        if (!(o instanceof Map))
            return false;
        Map<K,V> m = (Map<K,V>) o;
        if (m.size() != size())
            return false;

        try {
            Iterator<Entry<K,V>> i = entrySet().iterator();
            while (i.hasNext()) {
                Entry<K,V> e =;
                K key = e.getKey();
                V value = e.getValue();
                if (value == null) {
                    if (!(m.get(key)==null && m.containsKey(key)))
                        return false;
                } else {
                    if (!value.equals(m.get(key)))
                        return false;
        } catch (ClassCastException unused) {
            return false;
        } catch (NullPointerException unused) {
            return false;

        return true;

Comparing two different types of Maps

toString fails miserably when comparing a TreeMap and HashMap though equals does compare contents correctly.


public static void main(String args[]) {
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("2", "whatever2");
map.put("1", "whatever1");
TreeMap<String, Object> map2 = new TreeMap<String, Object>();
map2.put("2", "whatever2");
map2.put("1", "whatever1");

System.out.println("Are maps equal (using equals):" + map.equals(map2));
System.out.println("Are maps equal (using toString().equals()):"
        + map.toString().equals(map2.toString()));



Are maps equal (using equals):true
Are maps equal (using toString().equals()):false
Map1:{2=whatever2, 1=whatever1}
Map2:{1=whatever1, 2=whatever2}

How to explicitly obtain post data in Spring MVC?

Spring MVC runs on top of the Servlet API. So, you can use HttpServletRequest#getParameter() for this:

String value1 = request.getParameter("value1");
String value2 = request.getParameter("value2");

The HttpServletRequest should already be available to you inside Spring MVC as one of the method arguments of the handleRequest() method.

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.

Java - Using Accessor and Mutator methods

Let's go over the basics: "Accessor" and "Mutator" are just fancy names fot a getter and a setter. A getter, "Accessor", returns a class's variable or its value. A setter, "Mutator", sets a class variable pointer or its value.

So first you need to set up a class with some variables to get/set:

public class IDCard
    private String mName;
    private String mFileName;
    private int mID;


But oh no! If you instantiate this class the default values for these variables will be meaningless. B.T.W. "instantiate" is a fancy word for doing:

IDCard test = new IDCard();

So - let's set up a default constructor, this is the method being called when you "instantiate" a class.

public IDCard()
    mName = "";
    mFileName = "";
    mID = -1;

But what if we do know the values we wanna give our variables? So let's make another constructor, one that takes parameters:

public IDCard(String name, int ID, String filename)
    mName = name;
    mID = ID;
    mFileName = filename;

Wow - this is nice. But stupid. Because we have no way of accessing (=reading) the values of our variables. So let's add a getter, and while we're at it, add a setter as well:

public String getName()
    return mName;

public void setName( String name )
    mName = name;

Nice. Now we can access mName. Add the rest of the accessors and mutators and you're now a certified Java newbie. Good luck.

SOAP request to WebService with java

I have come across other similar question here. Both of above answers are perfect, but here trying to add additional information for someone looking for SOAP1.1, and not SOAP1.2.

Just change one line code provided by @acdcjunior, use SOAPMessageFactory1_1Impl implementation, it will change namespace to xmlns:soap="", which is SOAP1.1 implementation.

Change callSoapWebService method first line to following.

SOAPMessage soapMessage = SOAPMessageFactory1_1Impl.newInstance().createMessage();

I hope it will be helpful to others.

How to load a resource bundle from a file resource in Java?

I think that you want the file's parent to be on the classpath, not the actual file itself.

Try this (may need some tweaking):

String path = "c:/temp/mybundle.txt"; fl = new;

try {
   resourceURL = fl.getParentFile().toURL();
} catch (MalformedURLException e) {

URLClassLoader urlLoader = new URLClassLoader(new[]{resourceURL});
java.util.ResourceBundle bundle = java.util.ResourceBundle.getBundle("mybundle.txt", 
                java.util.Locale.getDefault(), urlLoader );

What's the main difference between Java SE and Java EE?

Java SE refers to the standard version of Java and its libraries. Java EE refers to the Enterprise edition of Java which is used to deploy web applications.

A cycle was detected in the build path of project xxx - Build Path Problem

Eclipse had a bug which reported more cycles than necessary. This has been fixed with the 2019-12 release. See

Determine file creation date in Java

The API of only supports getting the last modified time. And the Internet is very quiet on this topic as well.

Unless I missed something significant, the Java library as is (up to but not yet including Java 7) does not include this capability. So if you were desperate for this, one solution would be to write some C(++) code to call system routines and call it using JNI. Most of this work seems to be already done for you in a library called JNA, though.

You may still need to do a little OS specific coding in Java for this, though, as you'll probably not find the same system calls available in Windows and Unix/Linux/BSD/OS X.

slf4j: how to log formatted message, object array, exception

In addition to @Ceki 's answer, If you are using logback and setup a config file in your project (usually logback.xml), you can define the log to plot the stack trace as well using

    <pattern>%date |%-5level| [%thread] [%file:%line] - %msg%n%ex{full}</pattern> 

the %ex in pattern is what makes the difference

Java Comparator class to sort arrays

The answer from @aioobe is excellent. I just want to add another way for Java 8.

int[][] twoDim = { { 1, 2 }, { 3, 7 }, { 8, 9 }, { 4, 2 }, { 5, 3 } };

Arrays.sort(twoDim, (int[] o1, int[] o2) -> o2[0] - o1[0]);


For me it's intuitive and easy to remember with Java 8 syntax.

Spring Maven clean error - The requested profile "pom.xml" could not be activated because it does not exist

Bumped into same warning. If you specified goals and built project using "Run as -> Maven build..." option check and remove pom.xml from Profiles: just below Goals:

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

@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public User getUser() {
    return user;

I have the same problems, I solved it by add @Access(AccessType.PROPERTY)

DTO and DAO concepts and MVC

DTO is an abbreviation for Data Transfer Object, so it is used to transfer the data between classes and modules of your application.

  • DTO should only contain private fields for your data, getters, setters, and constructors.
  • DTO is not recommended to add business logic methods to such classes, but it is OK to add some util methods.

DAO is an abbreviation for Data Access Object, so it should encapsulate the logic for retrieving, saving and updating data in your data storage (a database, a file-system, whatever).

Here is an example of how the DAO and DTO interfaces would look like:

interface PersonDTO {
    String getName();
    void setName(String name);

interface PersonDAO {
    PersonDTO findById(long id);
    void save(PersonDTO person);

The MVC is a wider pattern. The DTO/DAO would be your model in the MVC pattern.
It tells you how to organize the whole application, not just the part responsible for data retrieval.

As for the second question, if you have a small application it is completely OK, however, if you want to follow the MVC pattern it would be better to have a separate controller, which would contain the business logic for your frame in a separate class and dispatch messages to this controller from the event handlers.
This would separate your business logic from the view.

Maven Installation OSX Error Unsupported major.minor version 51.0

In Eclipse, you don't need to change JAVA_HOME, you just need to change the run configuration for Maven to something above 1.6 (even if your project is on Java 6, Maven shouldn't be). Right-click the project, choose Maven Build or Run As > Run Configurations and set the correct JDK version.

How to check if a String is numeric in Java

Here is my class for checking if a string is numeric. It also fixes numerical strings:


  1. Removes unnecessary zeros ["12.0000000" -> "12"]
  2. Removes unnecessary zeros ["12.0580000" -> "12.058"]
  3. Removes non numerical characters ["12.00sdfsdf00" -> "12"]
  4. Handles negative string values ["-12,020000" -> "-12.02"]
  5. Removes multiple dots ["-" -> "-12.02"]
  6. No extra libraries, just standard Java

Here you go...

public class NumUtils {
     * Transforms a string to an integer. If no numerical chars returns a String "0".
     * @param str
     * @return retStr
    static String makeToInteger(String str) {
        String s = str;
        double d;
        d = Double.parseDouble(makeToDouble(s));
        int i = (int) (d + 0.5D);
        String retStr = String.valueOf(i);
        System.out.printf(retStr + "   ");
        return retStr;

     * Transforms a string to an double. If no numerical chars returns a String "0".
     * @param str
     * @return retStr
    static String makeToDouble(String str) {

        Boolean dotWasFound = false;
        String orgStr = str;
        String retStr;
        int firstDotPos = 0;
        Boolean negative = false;

        //check if str is null

        //check if first sign is "-"
        if (str.charAt(0) == '-') {
            negative = true;

        //check if str containg any number or else set the string to '0'
        if (!str.matches(".*\\d+.*")) {
            str = "0";

        //Replace ',' with '.'  (for some european users who use the ',' as decimal separator)
        str = str.replaceAll(",", ".");
        str = str.replaceAll("[^\\d.]", "");

        //Removes the any second dots
        for (int i_char = 0; i_char < str.length(); i_char++) {
            if (str.charAt(i_char) == '.') {
                dotWasFound = true;
                firstDotPos = i_char;
        if (dotWasFound) {
            String befDot = str.substring(0, firstDotPos + 1);
            String aftDot = str.substring(firstDotPos + 1, str.length());
            aftDot = aftDot.replaceAll("\\.", "");
            str = befDot + aftDot;

        //Removes zeros from the begining
        double uglyMethod = Double.parseDouble(str);
        str = String.valueOf(uglyMethod);

        //Removes the .0
        str = str.replaceAll("([0-9])\\.0+([^0-9]|$)", "$1$2");

        retStr = str;

        if (negative) {
            retStr = "-"+retStr;

        return retStr;


    static boolean isNumeric(String str) {
        try {
            double d = Double.parseDouble(str);
        } catch (NumberFormatException nfe) {
            return false;
        return true;


ArrayList filter

write your self a filter function

 public List<T> filter(Predicate<T> criteria, List<T> list) {

And then use

    list = new Test().filter(x -> x > 2, list);

This is the most neat version in Java, but needs JDK 1.8 to support lambda calculus

crudrepository findBy method signature with multiple in operators?

The following signature will do:

List<Email> findByEmailIdInAndPincodeIn(List<String> emails, List<String> pinCodes);

Spring Data JPA supports a large number of keywords to build a query. IN and AND are among them.

Is it bad practice to use break to exit a loop in Java?

The JLS specifies a break is an abnormal termination of a loop. However, just because it is considered abnormal does not mean that it is not used in many different code examples, projects, products, space shuttles, etc. The JVM specification does not state either an existence or absence of a performance loss, though it is clear code execution will continue after the loop.

However, code readability can suffer with odd breaks. If you're sticking a break in a complex if statement surrounded by side effects and odd cleanup code, with possibly a multilevel break with a label(or worse, with a strange set of exit conditions one after the other), it's not going to be easy to read for anyone.

If you want to break your loop by forcing the iteration variable to be outside the iteration range, or by otherwise introducing a not-necessarily-direct way of exiting, it's less readable than break.

However, looping extra times in an empty manner is almost always bad practice as it takes extra iterations and may be unclear.

How to install Java 8 on Mac

I have applications that use both Java 7 and 8 and have to go back and forth all the time.

I use this script written by Johan:

You can now set it at startup or call the script afterwards.
Install the JDK for Mac.

Java 7

Java 8

Updated recommendation!!:

Use jenv and homebrew.

Then its just jenv global oracle6401.6.0.39 and its set.

How do I check if a file exists in Java?

You can make it this way

import java.nio.file.Paths;

String file = "myfile.sss";
    // somethinh

how do I get eclipse to use a different compiler version for Java?

Just to clarify, do you have JAVA_HOME set as a system variable or set in Eclipse classpath variables? I'm pretty sure (but not totally sure!) that the system variable is used by the command line compiler (and Ant), but that Eclipse modifies this accroding to the JDK used

How to use PrintWriter and File classes in Java?

Well I think firstly keep whole main into try catch(or you can use as public static void main(String arg[]) throws IOException ) and then also use full path of file in which you are writing as

PrintWriter printWriter = new PrintWriter ("C:/Users/Me/Desktop/directory/file.txt");

all those directies like users,Me,Desktop,directory should be user made. java wont make directories own its own. it should be as

public class PrintWriterClass {

public static void main(String arg[]) throws IOException{
    PrintWriter pw = new PrintWriter("C:/Users/Me/Desktop/directory/file.txt");


How to enable TLS 1.2 in Java 7

To force enable TLSv1.2 in JRE7u_80 I had to use following code snippet before creating JDBC connection.


public static void enableTLSv12ForMssqlJdbc() throws NoSuchAlgorithmException
    ProviderList providerList = Providers.getProviderList();
    GetInstance.Instance instance = GetInstance.getInstance("SSLContext", SSLContextSpi.class, "TLS");
    for (Provider provider : providerList.providers())
        if (provider == instance.provider)
            provider.put("Alg.Alias.SSLContext.TLS", "TLSv1.2");

Able to connect to Windows 10 with SQL server 2017 & TLSv1.2 enabled OS.

How to import a class from default package

  1. Create "root" package (folder) in your project, for example.

    package source; (.../path_to_project/source/)

  2. Move YourClass.class into a source folder. (.../path_to_project/source/YourClass.class)

  3. Import like this

    import source.YourClass;

Assert that a WebElement is not present using Selenium WebDriver with java

boolean titleTextfield = driver.findElement("widget_polarisCommunityInput_113_title")).isDisplayed();
assertFalse(titleTextfield, "Title text field present which is not expected");

How to create a generic array?

Problem is that while runtime generic type is erased so new E[10] would be equivalent to new Object[10].

This would be dangerous because it would be possible to put in array other data than of E type. That is why you need to explicitly say that type you want by either

How to add an extra source directory for maven to compile and include in the build jar?

NOTE: This solution will just move the java source files to the target/classes directory and will not compile the sources.

Update the pom.xml as -


Delete all files in directory (but not directory) - one liner solution

Java 8 Stream

This deletes only files from ABC (sub-directories are untouched): File("C:/test/ABC/").listFiles()).forEach(File::delete);

This deletes only files from ABC (and sub-directories):


^ This version requires handling the IOException /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

If you are running in Android 29 then you have to use scoped storage or for now, you can bypass this issue by using:


in manifest in the application tag.

How can I show/hide component with JSF?

Generally, you need to get a handle to the control via its clientId. This example uses a JSF2 Facelets view with a request-scope binding to get a handle to the other control:

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns=""
      <h:button value="toggle"
               onclick="toggle('#{}'); return false;" />
      <h:inputText binding="#{}" id="x" style="display: block" />
    <script type="text/javascript">
      function toggle(id) {
        var element = document.getElementById(id);
        if( == 'block') {
 = 'none';
        } else {
 = 'block'

Exactly how you do this will depend on the version of JSF you're working on. See this blog post for older JSF versions: JSF: working with component identifiers.

What does Java option -Xmx stand for?

-Xmx sets the Maximum Heap size :connection timed out: connect?

Number (1): The IP was incorrect - is the correct answer. The /etc/hosts file (a.k.a. C:\Windows\system32\drivers\etc\hosts ) had an incorrect entry for the local machine name. Corrected the 'hosts' file and Camel runs very well. Thanks for the pointer.

How can I get relative path of the folders in my android project?

File relativeFile = new File(getClass().getResource("/icons/forIcon.png").toURI());

Java. Implicit super constructor Employee() is undefined. Must explicitly invoke another constructor

ProductionWorker extends Employee, thus it is said that it has all the capabilities of an Employee. In order to accomplish that, Java automatically puts a super(); call in each constructor's first line, you can put it manually but usually it is not necessary. In your case, it is necessary because the call to super(); cannot be placed automatically due to the fact that Employee's constructor has parameters.

You either need to define a default constructor in your Employee class, or call super('Erkan', 21, new Date()); in the first line of the constructor in ProductionWorker.

Java "lambda expressions not supported at this language level"

Possible Cause #1 (same as the first 3 answers for this question): Project Structure Settings

  1. File > Project Structure > Under Project Settings, go to Project > set Project SDK to 1.8 (with version 65 or above, latest is 112) and set Project Language Level to 8.

  2. File > Project Structure > Under Platform Settings, go to Project > ensure that your JDK home path is set to 1.8 (with version 65 or above, latest is 112).

If the above does not work, check the target bytecode version of your compiler and move on to Possible Cause #2.

Possible Cause #2: Compiler

  1. File > Settings > Build, Execution, Deployment > Under Compiler, go to Java Compiler > set your Project Bytecode Version to 1.8, as well as all the Target Bytecode Version for your modules. Click Apply and hit OK. Restart your IntelliJ IDE. Lambda expression was accepted in my IDE at this point.

Best wishes :)

Lightweight workflow engine for Java

I agree with the guys that already posted responses here, or part of their responses anyway :P, but as here in the company where I am currently working we had a similar challenge I took the liberty of adding my opinion, based on our experience.

We needed to migrate an application that was using the jBPM workflow engine in a production related applications and as there were quite a few challenges in maintaining the application we decided to see if there are better options on the market. We came to the list already mentioned:

  • Activiti (planned to try it through a prototype)
  • Bonita (planned to try it through a prototype)
  • jBPM (disqualified due to past experience)

We decided not to use jBPM anymore as our initial experience with it was not the best, besides this the backwards compatibility was broken with every new version that was released.

Finally the solution that we used, was to develop a lightweight workflow engine, based on annotations having activities and processes as abstractions. It was more or less a state machine that did it's job.

Another point that is worth mentioning when discussing about workflow engine is the fact they are dependent on the backing DB - it was the case with the two workflow engines I have experience with (SAG webMethods and jPBM) - and from my experience that was a little bit of an overhead especially during migrations between versions.

So, I would say that using an workflow engine is entitled only for applications that would really benefit from it and where most of the workflow of the applications is spinning around the workflow itself otherwise there are better tools for the job:

Regarding state machines, I came across this response that contains a rather complete collection of state machine java frameworks.

Hope this helps.

Most efficient way to check if a file is empty in Java on Windows

Stolen from

FileInputStream fis = new FileInputStream(new File("file_name"));  
int b =;  
if (b == -1)  
  System.out.println("!!File " + file_name + " emty!!");  

Updated: My first answer was premature and contained a bug.

Why am I getting Unknown error in line 1 of pom.xml?

You must to upgrade the m2e connector. It's a known bug, but there is a solution:

  1. Into Eclipse click "Help" > "Install new Software..."

  2. Appears a window. In the "Install" window:

    2a. Into the input box "Work with", enter next site location and press Enter

    2b. Appears a lot of information into "Name" input Box. Select all the items

    2c. Click "Next" Button.

Finish the installation and restart Eclipse.

How to change the background color on a Java panel?

You could call:


Or add a JPanel to the JFrame your using. Then add your components to the JPanel. This will allow you to call


on the JPanel to set the background color.

Custom fonts and XML layouts (Android)

I might have a simple answer for the question without extending the TextView and implementing a long code.

Code :

 TextView tv = (TextView) findViewById(;
    tv.setTypeface(Typeface.createFromAsset(getAssets(), "font.ttf"));

Place the custom font file in assets folder as usual and try this. It works for me. I just dont understand why peter has given such a huge code for this simple thing or he has given his answer in old version.

Java Array, Finding Duplicates

This program will print all duplicates value from array.

public static void main(String[] args) {

    int[] array = new int[] { -1, 3, 4, 4,4,3, 9,-1, 5,5,5, 5 };

 boolean isMatched = false;
 int lstMatch =-1;
      for(int i = 0; i < array.length; i++) {  
          try {
                if(array[i] == array[i+1]) { 
                    isMatched = true;
                    lstMatch = array[i+1]; 
                else if(isMatched) {
                    isMatched = false;
                    lstMatch = -1;
          }catch(Exception ex) {
              //TODO NA

      if(isMatched) {



Difference between request.getSession() and request.getSession(true)

Method with boolean argument :


returns new session, if the session is not associated with the request


returns null, if the session is not associated with the request.

Method without boolean argument :


returns new session, if the session is not associated with the request and returns the existing session, if the session is associated with the request.It won't return null.

How to redirect in a servlet filter?

In Filter the response is of ServletResponse rather than HttpServletResponse. Hence do the cast to HttpServletResponse.

HttpServletResponse httpResponse = (HttpServletResponse) response;

If using a context path:

httpResponse.sendRedirect(req.getContextPath() + "/login.jsp");

Also don't forget to call return; at the end.

Can't import javax.servlet.annotation.WebServlet

Go to

window->Preference->server->runtime environment

then choose your tomcat server. If the error is still there, then

right click project->properties>Targeted Runtimes

then check the server

Using Mockito with multiple calls to the same method with the same arguments

Related to @[Igor Nikolaev]'s answer from 8 years ago, using an Answer can be simplified somewhat using a lambda expression available in Java 8.

when(someMock.someMethod()).thenAnswer(invocation -> {

or more simply:

when(someMock.someMethod()).thenAnswer(invocation -> doStuff());

Caused By: java.lang.NoClassDefFoundError: org/apache/log4j/Logger

With the suggestions @jhadesdev and the explanations from others, I've found the issue here.

After adding the code to see what was visible to the various class loaders I found this:

All versions of log4j Logger: 

All versions of log4j visible from the classloader of the OAuthAuthorizer class: 

All versions of XMLConfigurator: 

All versions of XMLConfigurator visible from the classloader of the OAuthAuthorizer class: 

I noticed that another version of XMLConfigurator was possibly getting picked up. I decompiled that class and found this at line 60 (where the error was in the original stack trace) private static final Logger log = Logger.getLogger(XMLConfigurator.class); and that class was importing from org.apache.log4j.Logger!

So it was this class that was being loaded and used. My fix was to rename the jar file that contained this file as I can't find where I explicitly or indirectly load it. Which may pose a problem when I actually deploy.

Thanks for all help and the much needed lesson on class loading.

Why can't I enter a string in Scanner(, when calling nextLine()-method?

Scanner's buffer full when we take a input string through scan.nextLine(); so it skips the input next time . So solution is that we can create a new object of Scanner , the name of the object can be same as previous object......

Change keystore password from no password to a non blank password

Add -storepass to keytool arguments.

keytool -storepasswd -storepass '' -keystore mykeystore.jks

But also notice that -list command does not always require a password. I could execute follow command in both cases: without password or with valid password

$JAVA_HOME/bin/keytool -list -keystore $JAVA_HOME/jre/lib/security/cacerts

the getSource() and getActionCommand()


Returns the command string associated with this action. This string allows a "modal" component to specify one of several commands, depending on its state. For example, a single button might toggle between "show details" and "hide details". The source object and the event would be the same in each case, but the command string would identify the intended action.

IMO, this is useful in case you a single command-component to fire different commands based on it's state, and using this method your handler can execute the right lines of code.

JTextField has JTextField#setActionCommand(java.lang.String) method that you can use to set the command string used for action events generated by it.


Returns: The object on which the Event initially occurred.

We can use getSource() to identify the component and execute corresponding lines of code within an action-listener. So, we don't need to write a separate action-listener for each command-component. And since you have the reference to the component itself, you can if you need to make any changes to the component as a result of the event.

If the event was generated by the JTextField then the ActionEvent#getSource() will give you the reference to the JTextField instance itself.

Java generics - why is "extends T" allowed but not "implements T"?

It may be that the base type is a generic parameter, so the actual type may be an interface of a class. Consider:

class MyGen<T, U extends T> {

Also from client code perspective interfaces are almost indistinguishable from classes, whereas for subtype it is important.

List of enum values in java

It is possible but you should use EnumSet instead

enum MyEnum {
    ONE, TWO;
    public static final EnumSet<MyEnum> all = EnumSet.of(ONE, TWO);

How to start anonymous thread class

Add: now you can use lambda to simplify your syntax. Requirement: Java 8+

public class A {
    public static void main(String[] arg)
        Thread th = new Thread(() -> {System.out.println("blah");});

Difference between Static and final?

final -

1)When we apply "final" keyword to a variable,the value of that variable remains constant. (or) Once we declare a variable as final.the value of that variable cannot be changed.

2)It is useful when a variable value does not change during the life time of a program

static -

1)when we apply "static" keyword to a variable ,it means it belongs to class.
2)When we apply "static" keyword to a method,it means the method can be accessed without creating any instance of the class

String Pattern Matching In Java

You can use the Pattern class for this. If you want to match only word characters inside the {} then you can use the following regex. \w is a shorthand for [a-zA-Z0-9_]. If you are ok with _ then use \w or else use [a-zA-Z0-9].

String URL = "https://localhost:8080/sbs/01.00/sip/dreamworks/v/01.00/cui/print/$fwVer/{$fwVer}/$lang/en/$model/{$model}/$region/us/$imageBg/{$imageBg}/$imageH/{$imageH}/$imageSz/{$imageSz}/$imageW/{$imageW}/movie/Kung_Fu_Panda_two/categories/3D_Pix/item/{item}/_back/2?$uniqueID={$uniqueID}";
Pattern pattern = Pattern.compile("/\\{\\w+\\}/");
Matcher matcher = pattern.matcher(URL);
if (matcher.find()) {
    System.out.println(; //prints /{item}/
} else {
    System.out.println("Match not found");

How to timeout a thread

Consider using an instance of ExecutorService. Both invokeAll() and invokeAny() methods are available with a timeout parameter.

The current thread will block until the method completes (not sure if this is desirable) either because the task(s) completed normally or the timeout was reached. You can inspect the returned Future(s) to determine what happened.

Run cmd commands through Java

The easiest way would be to use Runtime.getRuntime.exec().

For example, to get a registry value for the default browser on Windows:

String command = "REG QUERY HKEY_CLASSES_ROOT\\http\\shell\\open\\command";
    Process process = Runtime.getRuntime().exec(command);
} catch (IOException e)

Then use a Scanner to get the output of the command, if necessary.

Scanner kb = new Scanner(process.getInputStream());

Note: the \ is an escape character in a String, and must be escaped to work properly (hence the \\).

However, there is no executable called cd, because it can't be implemented in a separate process.

The one case where the current working directory matters is executing an external process (using ProcessBuilder or Runtime.exec()). In those cases you can specify the working directory to use for the newly started process explicitly.

Easiest way for your command:

System.setProperty("user.dir", "C:\\Program Files\\Flowella");

Does Hibernate create tables in the database automatically

Hibernate can create a table, hibernate sequence and tables used for many-to-many mapping on your behalf but you have to explicitly configure it by calling setProperty("", "create") of the Configuration object. By Default, it just validates the schema with DB and fails if anything not already exists by giving error "ORA-00942: table or view does not exist".

If you do above configuration then order of performed actions will be:- a) Drop all tables and sequence and do not give an error if they are not already present. b) create all table and sequence c) alter tables with constraints d) insert data into it.

How to iterate through SparseArray?

If you use Kotlin, you can use extension functions as such, for example:

fun <T> LongSparseArray<T>.valuesIterator(): Iterator<T> {
    val nSize = this.size()
    return object : Iterator<T> {
        var i = 0
        override fun hasNext(): Boolean = i < nSize
        override fun next(): T = valueAt(i++)

fun <T> LongSparseArray<T>.keysIterator(): Iterator<Long> {
    val nSize = this.size()
    return object : Iterator<Long> {
        var i = 0
        override fun hasNext(): Boolean = i < nSize
        override fun next(): Long = keyAt(i++)

fun <T> LongSparseArray<T>.entriesIterator(): Iterator<Pair<Long, T>> {
    val nSize = this.size()
    return object : Iterator<Pair<Long, T>> {
        var i = 0
        override fun hasNext(): Boolean = i < nSize
        override fun next() = Pair(keyAt(i), valueAt(i++))

You can also convert to a list, if you wish. Example:


I think it might even be safe to delete items using remove on the LongSparseArray itself (not on the iterator), as it is in ascending order.

EDIT: Seems there is even an easier way, by using collection-ktx (example here) . It's implemented in a very similar way to what I wrote, actally.

Gradle requires this:

implementation 'androidx.core:core-ktx:#'
implementation 'androidx.collection:collection-ktx:#'

Here's the usage for LongSparseArray :

    val sparse= LongSparseArray<String>()
    for (key in sparse.keyIterator()) {
    for (value in sparse.valueIterator()) {
    sparse.forEach { key, value -> 

And for those that use Java, you can use LongSparseArrayKt.keyIterator , LongSparseArrayKt.valueIterator and LongSparseArrayKt.forEach , for example. Same for the other cases.

How can I disable the Maven Javadoc plugin from the command line?

You can use the maven.javadoc.skip property to skip execution of the plugin, going by the Mojo's javadoc. You can specify the value as a Maven property:


or as a command-line argument: -Dmaven.javadoc.skip=true, to skip generation of the Javadocs.

How to extract a string between two delimiters

If you have just a pair of brackets ( [] ) in your string, you can use indexOf():

String str = "ABC[ This is the text to be extracted ]";    
String result = str.substring(str.indexOf("[") + 1, str.indexOf("]"));

Java recursive Fibonacci sequence

Michael Goodrich et al provide a really clever algorithm in Data Structures and Algorithms in Java, for solving fibonacci recursively in linear time by returning an array of [fib(n), fib(n-1)].

public static long[] fibGood(int n) {
    if (n < = 1) {
        long[] answer = {n,0};
        return answer;
    } else {
        long[] tmp = fibGood(n-1);
        long[] answer = {tmp[0] + tmp[1], tmp[0]};
        return answer;

This yields fib(n) = fibGood(n)[0].

JSONObject - How to get a value?

If it's a deeper key/value you're after and you're not dealing with arrays of keys/values at each level, you could recursively search the tree:

public static String recurseKeys(JSONObject jObj, String findKey) throws JSONException {
    String finalValue = "";
    if (jObj == null) {
        return "";

    Iterator<String> keyItr = jObj.keys();
    Map<String, String> map = new HashMap<>();

    while(keyItr.hasNext()) {
        String key =;
        map.put(key, jObj.getString(key));

    for (Map.Entry<String, String> e : (map).entrySet()) {
        String key = e.getKey();
        if (key.equalsIgnoreCase(findKey)) {
            return jObj.getString(key);

        // read value
        Object value = jObj.get(key);

        if (value instanceof JSONObject) {
            finalValue = recurseKeys((JSONObject)value, findKey);

    // key is not found
    return finalValue;


JSONObject jObj = new JSONObject(jsonString);
String extract = recurseKeys(jObj, "extract");

Using Map code from

How to use HTTP_X_FORWARDED_FOR properly?

HTTP_CLIENT_IP is the most reliable way of getting the user's IP address. Next is HTTP_X_FORWARDED_FOR, followed by REMOTE_ADDR. Check all three, in that order, assuming that the first one that is set (isset($_SERVER['HTTP_CLIENT_IP']) returns true if that variable is set) is correct. You can independently check if the user is using a proxy using various methods. Check this out.

How to install mod_ssl for Apache httpd?

I found I needed to enable the SSL module in Apache (obviously prefix commands with sudo if you are not running as root):

a2enmod ssl

then restart Apache:

/etc/init.d/apache2 restart

More details of SSL in Apache for Ubuntu / Debian here.

Sorting a list using Lambda/Linq to objects

Building the order by expression can be read here

Shamelessly stolen from the page in link:

// First we define the parameter that we are going to use
// in our OrderBy clause. This is the same as "(person =>"
// in the example above.
var param = Expression.Parameter(typeof(Person), "person");

// Now we'll make our lambda function that returns the
// "DateOfBirth" property by it's name.
var mySortExpression = Expression.Lambda<Func<Person, object>>(Expression.Property(param, "DateOfBirth"), param);

// Now I can sort my people list.
Person[] sortedPeople = people.OrderBy(mySortExpression).ToArray();

Get only records created today in laravel

$today = Carbon\Carbon::now()->format('Y-m-d').'%';
->where('created_at', 'like', $today);

Hope it will help you

What is the command for cut copy paste a file from one directory to other directory

use the xclip which is command line interface to X selections


apt-get install xclip


echo "test xclip " > /tmp/test.xclip
xclip -i < /tmp/test.xclip
xclip -o > /tmp/test.xclip.out

cat /tmp/test.xclip.out   # "test xclip"


Check if a string is html or not

If you're creating a regex from a string literal you need to escape any backslashes:

var htmlRegex = new RegExp("<([A-Za-z][A-Za-z0-9]*)\\b[^>]*>(.*?)</\\1>");
// extra backslash added here ---------------------^ and here -----^

This is not necessary if you use a regex literal, but then you need to escape forward slashes:

var htmlRegex = /<([A-Za-z][A-Za-z0-9]*)\b[^>]*>(.*?)<\/\1>/;
// forward slash escaped here ------------------------^

Also your jsfiddle didn't work because you assigned an onload handler inside another onload handler - the default as set in the Frameworks & Extensions panel on the left is to wrap the JS in an onload. Change that to a nowrap option and fix the string literal escaping and it "works" (within the constraints everybody has pointed out in comments):

As far as I know JavaScript regular expressions don't have back-references. So this part of your expression:


won't work in JS (but would work in some other languages).

Removing duplicate rows in Notepad++

You may need a plugin to do this. You can try the command line cc.ddl(delete duplicate lines) of ConyEdit. It is a cross-editor plugin for the text editors, including Notepad++.

With ConyEdit running in background, follow the steps below:

  1. enter the command line cc.ddl at the end of the text.
  2. copy the text and the command line.
  3. paste, then you will see what you want.

enter image description here

ASP.Net MVC Redirect To A Different View

Here's what you can do:

return View("another view name", anotherviewmodel);

Twitter bootstrap float div right

bootstrap 3 has a class to align the text within a div

<div class="text-right">

will align the text on the right

<div class="pull-right">

will pull to the right all the content not only the text

How do I check out an SVN project into Eclipse as a Java project?

If the were checked as plugin-projects, than you just need to check them out. But do not select the "trunk"(for example) to speed it up. You must select all the projects you want to check out and proceed. Eclipse will than recognize them as such.

Calculating and printing the nth prime number

Although many correct and detailed explanations are available. but here is my C implementation:


int pk,qd,am,no,c=0;
printf("\n Enter the Number U want to Find");
return 0;

Angular: How to update queryParams without changing route

I ended up combining urlTree with location.go

const urlTree = this.router.createUrlTree([], {
       relativeTo: this.route,
       queryParams: {
           newParam: myNewParam,
       queryParamsHandling: 'merge',


Not sure if toString can cause problems, but unfortunately location.go, seems to be string based.

How to add (vertical) divider to a horizontal LinearLayout?

If the answer of Kapil Vats is not working try something like this:


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

    <size android:width="22dip"/>
    <solid android:color="#00ff00"/>




I encountered an issue where the padding attribute wasn't working, thus I had to set the height of the divider directly in the divider.


If you want to use it in vertical LinearLayout, make a new one, like this: drawable/divider_vertical_green_22.xml

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

    <size android:height="22dip"/>
    <solid android:color="#00ff00"/>


Bootstrap carousel multiple frames at once

Update 2019-03-06 -- Bootstrap v4.3.1

It seems the new Bootstrap version adds a margin-right: -100% to each item, therefore in the responsive solution given in the most upvoted answer in here, this property should be reset, e.g.:

.carousel-inner .carousel-item {
    margin-right: inherit;

A working codepen with v4.3.1 in LESS.

Update and left outer join statements

In mysql the SET clause needs to come after the JOIN. Example:

    LEFT JOIN a ON = e.aid
    SET = 2
        e.type = 'user' AND = 'US';

How can I insert data into Database Laravel?

The error MethodNotAllowedHttpException means the route exists, but the HTTP method (GET) is wrong. You have to change it to POST:

Route::post('test/register', array('uses'=>'TestController@create'));

Also, you need to hash your passwords:

public function create()
    $user = new User;

    $user->username = Input::get('username');
    $user->email = Input::get('email');
    $user->password = Hash::make(Input::get('password'));

    return Redirect::back();

And I removed the line:

$user= Input::all();

Because in the next command you replace its contents with

$user = new User;

To debug your Input, you can, in the first line of your controller:

dd( Input::all() );

It will display all fields in the input.

How can you use optional parameters in C#?

You could use method overloading...

GetFooBar(int a)
GetFooBar(int a, int b)

It depends on the method signatures, the example I gave is missing the "int b" only method because it would have the same signature as the "int a" method.

You could use Nullable types...

GetFooBar(int? a, int? b)

You could then check, using a.HasValue, to see if a parameter has been set.

Another option would be to use a 'params' parameter.

GetFooBar(params object[] args)

If you wanted to go with named parameters would would need to create a type to handle them, although I think there is already something like this for web apps.

T-SQL get SELECTed value of stored procedure

There is also a combination, you can use a return value with a recordset:

--Stored Procedure--



        [Name] VARCHAR(50)

    INSERT INTO @Temp VALUES ('Mark') 
    INSERT INTO @Temp VALUES ('John') 
    INSERT INTO @Temp VALUES ('Jane') 
    INSERT INTO @Temp VALUES ('Mary') 

    -- Get recordset
    SELECT * FROM @Temp

    DECLARE @ReturnValue INT
    SELECT @ReturnValue = COUNT([Name]) FROM @Temp

    -- Return count
    RETURN @ReturnValue


--Calling Code--

DECLARE @SelectedValue int
EXEC @SelectedValue = [TestProc] 

SELECT @SelectedValue


enter image description here

How do I set the size of an HTML text box?

Just use:

textarea {
    width: 200px;


input[type="text"] {
    width: 200px;

Depending on what you mean by 'textbox'.

Long Press in JavaScript?

You can use jquery-mobile's taphold. Include the jquery-mobile.js and the following code will work fine

   $(this).hide(); //your code

cannot import name patterns

patterns module is not supported.. mine worked with this.

from django.conf.urls import *
from django.contrib import admin

urlpatterns = [
    url(r'^admin/', include(,
    # ... your url patterns

what exactly is device pixel ratio?

Device Pixel Ratio == CSS Pixel Ratio

In the world of web development, the device pixel ratio (also called CSS Pixel Ratio) is what determines how a device's screen resolution is interpreted by the CSS.

A browser's CSS calculates a device's logical (or interpreted) resolution by the formula:


For example:

Apple iPhone 6s

  • Actual Resolution: 750 x 1334
  • CSS Pixel Ratio: 2
  • Logical Resolution:


When viewing a web page, the CSS will think the device has a 375x667 resolution screen and Media Queries will respond as if the screen is 375x667. But the rendered elements on the screen will be twice as sharp as an actual 375x667 screen because there are twice as many physical pixels in the physical screen.

Some other examples:

Samsung Galaxy S4

  • Actual Resolution: 1080 x 1920
  • CSS Pixel Ratio: 3
  • Logical Resolution:


iPhone 5s

  • Actual Resolution: 640 x 1136
  • CSS Pixel Ratio: 2
  • Logical Resolution:


Why does the Device Pixel Ratio exist?

The reason that CSS pixel ratio was created is because as phones screens get higher resolutions, if every device still had a CSS pixel ratio of 1 then webpages would render too small to see.

A typical full screen desktop monitor is a roughly 24" at 1920x1080 resolution. Imagine if that monitor was shrunk down to about 5" but had the same resolution. Viewing things on the screen would be impossible because they would be so small. But manufactures are coming out with 1920x1080 resolution phone screens consistently now.

So the device pixel ratio was invented by phone makers so that they could continue to push the resolution, sharpness and quality of phone screens, without making elements on the screen too small to see or read.

Here is a tool that also tells you your current device's pixel density:

Get checkbox values using checkbox name using jquery

I would like to add that if you're trying to get all of the check-boxes with that name that have been selected, you would want to use the following syntax:

$("[name='bla[]']:checked").each(function () {
    // do stuff

Make sure there is not a space between the closing ] and :checked

How can I check MySQL engine type for a specific table?

SHOW CREATE TABLE <tablename>;

Less parseable but more readable than SHOW TABLE STATUS.

Sqlite: CURRENT_TIMESTAMP is in GMT, not the timezone of the machine

You can also just convert the time column to a timestamp by using strftime():

SELECT strftime('%s', timestamp) as timestamp FROM ... ;

Gives you:


'timestamp' table column can be a text field even, using the current_timestamp as DEFAULT.

Without strftime:

SELECT timestamp FROM ... ;

Gives you:

2016-02-03 17:51:28

How can I use Python to get the system hostname?

Both of these are pretty portable:

import platform

import socket

Any solutions using the HOST or HOSTNAME environment variables are not portable. Even if it works on your system when you run it, it may not work when run in special environments such as cron.

How do I format my oracle queries so the columns don't wrap?

I use a generic query I call "dump" (why? I don't know) that looks like this:


spool &1..txt


spool off

I then call SQL*Plus passing the actual SQL script I want to run as an argument:

sqlplus -S user/password@database @dump.sql my_real_query.sql

The result is written to a file



What is an IIS application pool?

An application pool is a group of one or more URLs that are served by a worker process or set of worker processes. Application pools are used to separate sets of IIS worker processes that share the same configuration and application boundaries. Application pools are used to isolate our web application for better security, reliability, availability and performance, and they keep running without impacting each other.

"for loop" with two variables?

I think you are looking for nested loops.

Example (based on your edit):



for it1, e1 in enumerate(t1):
    for it2, e2 in enumerate(t2):
        if e1==e2:

# t3=[(0, 0, 1), (2, 1, 'Hello'), (3, 2, (1, 2)), (4, 3, 999)]

Which can be reduced to a single comprehension:

[(it1,it2,e1) for it1, e1 in enumerate(t1) for it2, e2 in enumerate(t2) if e1==e2] 

But to find the common elements, you can just do:

print set(t1) & set(t2)
# set([(1, 2), 1, 'Hello', 999])

If your list contains non-hashable objects (like other lists, dicts) use a frozen set:

from collections import Iterable
s1=set(frozenset(e1) if isinstance(e1,Iterable) else e1 for e1 in t1)
s2=set(frozenset(e2) if isinstance(e2,Iterable) else e2 for e2 in t2)
print s1 & s2

How to manually trigger click event in ReactJS?

In a functional component this principle also works, it's just a slightly different syntax and way of thinking.

const UploadsWindow = () => {
  // will hold a reference for our real input file
  let inputFile = '';

  // function to trigger our input file click
  const uploadClick = e => {
    return false;

  return (
        ref={input => {
          // assigns a reference so we can trigger it later
          inputFile = input;

      <a href="#" className="btn" onClick={uploadClick}>
        Add or Drag Attachments Here


Is it possible to insert HTML content in XML document?

so long as your html content doesn't need to contain a CDATA element, you can contain the HTML in a CDATA element, otherwise you'll have to escape the XML entities.

<element><![CDATA[<p>your html here</p>]]></element>


<element>&lt;p&gt;your html here&lt;/p&gt;</element>

Traits vs. interfaces

The trait is same as a class we can use for multiple inheritance purposes and also code reusability.

We can use trait inside the class and also we can use multiple traits in the same class with 'use keyword'.

The interface is using for code reusability same as a trait

the interface is extend multiple interfaces so we can solve the multiple inheritance problems but when we implement the interface then we should create all the methods inside the class. For more info click below link:

Add marker to Google Map on Click

In 2017, the solution is:

map.addListener('click', function(e) {
    placeMarker(e.latLng, map);

function placeMarker(position, map) {
    var marker = new google.maps.Marker({
        position: position,
        map: map

Invalid application path

I also had this error.

My IIS Website has a Default Website with three (3) application directories below it.

I had each of my 3 application directories configured correctly to use .NET Framework v2.0 in the Application Pools.

Edit Application Pool

However, the Default Website never was configured. I didn't think it was necessary since all of my apps were contained within it.

My IIS Server's default configuration is .NET Framework v4.0, so I changed that to .NET v2.0:

Edit Default App Pool

After I did that, I no longer received the same error message.

Now, I see this:


I hope this information helps others.

How can I show and hide elements based on selected option with jQuery?

You are missing a :selected on the selector for show() - see the jQuery documentation for an example of how to use this.

In your case it will probably look something like this:

$('#'+$('#colorselector option:selected').val()).show();

What is an unsigned char?

unsigned char is the heart of all bit trickery. In almost ALL compiler for ALL platform an unsigned char is simply a byte and an unsigned integer of (usually) 8 bits that can be treated as a small integer or a pack of bits.

In addiction, as someone else has said, the standard doesn't define the sign of a char. so you have 3 distinct char types: char, signed char, unsigned char.

Simple way to get element by id within a div tag?

In HTML ids should be unique. I suggest you change your code to something like this:

<div id="div1" >
    <input type="text" name="edit1" id="edit1" />
    <input type="text" name="edit2" id="edit2" />
<div id="div2" >
    <input type="text" name="edit1" id="edit3" />
    <input type="text" name="edit2" id="edit4" />

Extract the first word of a string in a SQL Server query

Try This:

Select race_id, race_description
, Case patIndex ('%[ /-]%', LTrim (race_description))
    When 0 Then LTrim (race_description)
    Else substring (LTrim (race_description), 1, patIndex ('%[ /-]%', LTrim (race_description)) - 1)
End race_abbreviation

from tbl_races

Why do I get "'property cannot be assigned" when sending an SMTP email?

public static void SendMail(MailMessage Message)
    SmtpClient client = new SmtpClient();
    client.Host = "";
    client.Port = 587;
    client.UseDefaultCredentials = false;
    client.DeliveryMethod = SmtpDeliveryMethod.Network;
    client.EnableSsl = true;
    client.Credentials = new NetworkCredential("[email protected]", "password");

PHP "php://input" vs $_POST

So I wrote a function that would get the POST data from the php://input stream.

So the challenge here was switching to PUT, DELETE OR PATCH request method, and still obtain the post data that was sent with that request.

I'm sharing this maybe for someone with a similar challenge. The function below is what I came up with and it works. I hope it helps!

     * @method Post getPostData
     * @return array
     * Convert Content-Disposition to a post data
    function getPostData() : array
        // @var string $input
        $input = file_get_contents('php://input');

        // continue if $_POST is empty
        if (strlen($input) > 0 && count($_POST) == 0 || count($_POST) > 0) :

            $postsize = "---".sha1(strlen($input))."---";

            preg_match_all('/([-]{2,})([^\s]+)[\n|\s]{0,}/', $input, $match);

            // update input
            if (count($match) > 0) $input = preg_replace('/([-]{2,})([^\s]+)[\n|\s]{0,}/', '', $input);

            // extract the content-disposition
            preg_match_all("/(Content-Disposition: form-data; name=)+(.*)/m", $input, $matches);

            // let's get the keys
            if (count($matches) > 0 && count($matches[0]) > 0)
                $keys = $matches[2];

                foreach ($keys as $index => $key) :
                    $key = trim($key);
                    $key = preg_replace('/^["]/','',$key);
                    $key = preg_replace('/["]$/','',$key);
                    $key = preg_replace('/[\s]/','',$key);
                    $keys[$index] = $key;

                $input = preg_replace("/(Content-Disposition: form-data; name=)+(.*)/m", $postsize, $input);

                $input = preg_replace("/(Content-Length: )+([^\n]+)/im", '', $input);

                // now let's get key value
                $inputArr = explode($postsize, $input);

                // @var array $values
                $values = [];

                foreach ($inputArr as $index => $val) :
                    $val = preg_replace('/[\n]/','',$val);

                    if (preg_match('/[\S]/', $val)) $values[$index] = trim($val);


                // now combine the key to the values
                $post = [];

                // @var array $value
                $value = [];

                // update value
                foreach ($values as $i => $val) $value[] = $val;

                // push to post
                foreach ($keys as $x => $key) $post[$key] = isset($value[$x]) ? $value[$x] : '';

                if (is_array($post)) :

                    $newPost = [];

                    foreach ($post as $key => $val) :

                        if (preg_match('/[\[]/', $key)) :

                            $k = substr($key, 0, strpos($key, '['));
                            $child = substr($key, strpos($key, '['));
                            $child = preg_replace('/[\[|\]]/','', $child);
                            $newPost[$k][$child] = $val;


                            $newPost[$key] = $val;



                    $_POST = count($newPost) > 0 ? $newPost : $post;



        // return post array
        return $_POST;

Save string to the NSUserDefaults?

-(void)saveToUserDefaults:(NSString*)string_to_store keys:(NSString *)key_for_the_String
    NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];

    if (standardUserDefaults) {
        [standardUserDefaults setObject:string_to_store forKey:key_for_the_String];
        [standardUserDefaults synchronize];

And call it by:

[self saveToUserDefaults:@"string_to_store" : @"key_for_the_string"];

Retrieve the string by using:

NSString * stored_string = [[NSUserDefaults standardUserDefaults] stringforkey:key_for_the_String]

Very Simple Image Slider/Slideshow with left and right button. No autoplay

<script type="text/javascript">
                    $(document).ready(function(e) {
                            $("#imgprev").animate({height: "250px",width: "70%",left: "15%"},100).html("<img src='"+$(this).attr('src')+"' width='100%' height='100%' />"); 
                            $("#imgprev").animate({height: "0px",width: "0%",left: "50%"},100);
                    .mqimg{ cursor:pointer;}
                    <div style="position:relative; width:100%; height:1px; text-align:center;">`enter code here`
                    <div id="imgprev" style="position:absolute; display:block; box-shadow:2px 5px 10px #333; width:70%; height:0px; background:#999; left:15%; bottom:15px; "></div>
<img class='mqimg' src='spppimages/1.jpg' height='100px' />
<img class='mqimg' src='spppimages/2.jpg' height='100px' />
<img class='mqimg' src='spppimages/3.jpg' height='100px' />
<img class='mqimg' src='spppimages/4.jpg' height='100px' />
<img class='mqimg' src='spppimages/5.jpg' height='100px' />

How to ignore deprecation warnings in Python

Try the below code if you're Using Python3:

import sys

if not sys.warnoptions:
    import warnings

or try this...

import warnings

def fxn():
    warnings.warn("deprecated", DeprecationWarning)

with warnings.catch_warnings():

or try this...

import warnings

What is the convention in JSON for empty vs. null?

Empty array for empty collections and null for everything else.

Submit form using <a> tag

Is there any reason for not using a submit button and then styling it with css to match your other a tags?

I think this would reduce your dependency on having javascript enabled and still get the desired result.

How to exclude file only from root folder in Git

From the documentation:

If the pattern does not contain a slash /, git treats it as a shell glob pattern and checks for a match against the pathname relative to the location of the .gitignore file (relative to the toplevel of the work tree if not from a .gitignore file).

A leading slash matches the beginning of the pathname. For example, "/*.c" matches "cat-file.c" but not "mozilla-sha1/sha1.c".

So you should add the following line to your root .gitignore:


jquery, find next element by class

You cannot use next() in this scenario, if you look at the documentation it says:
Next() Get the immediately following sibling of each element in the set of matched elements. If a selector is provided, it retrieves the next sibling that matches the selector.

so if the second DIV was in the same TD then you could code:

// Won't work in your case

But since it's not, I don't see a point to use next(). You can instead code:


Apache error: _default_ virtualhost overlap on port 443

It is highly unlikely that adding NameVirtualHost *:443 is the right solution, because there are a limited number of situations in which it is possible to support name-based virtual hosts over SSL. Read this and this for some details (there may be better docs out there; these were just ones I found that discuss the issue in detail).

If you're running a relatively stock Apache configuration, you probably have this somewhere:

<VirtualHost _default_:443>

Your best bet is to either:

  • Place your additional SSL configuration into this existing VirtualHost container, or
  • Comment out this entire VirtualHost block and create a new one. Don't forget to include all the relevant SSL options.

Get cursor position (in characters) within a text Input field

   (function($) {
    $.fn.getCursorPosition = function() {
        var input = this.get(0);
        if (!input) return; // No (input) element found
        if (document.selection) {
            // IE
        return 'selectionStart' in input ? input.selectionStart:'' || Math.abs(document.selection.createRange().moveStart('character', -input.value.length));

How to present popover properly in iOS 8

I found a complete example of how to get this all to work so that you can always display a popover no matter the device/orientation

The key is to implement UIAdaptivePresentationControllerDelegate

func adaptivePresentationStyleForPresentationController(PC: UIPresentationController!) -> UIModalPresentationStyle {
    // This *forces* a popover to be displayed on the iPhone
    return .None

Then extend the example above (from Imagine Digital):

nav.popoverPresentationController!.delegate = implOfUIAPCDelegate

Return JSON for ResponseEntity<String>

The root of the problem is that Spring (via ResponseEntity, RestController, and/or ResponseBody) will use the contents of the string as the raw response value, rather than treating the string as JSON value to be encoded. This is true even when the controller method uses produces = MediaType.APPLICATION_JSON_VALUE, as in the question here.

It's essentially like the difference between the following:

// yields: This is a String
System.out.println("This is a String");

// yields: "This is a String"
System.out.println("\"This is a String\"");

The first output cannot be parsed as JSON, but the second output can.

Something like '"'+myString+'"' is probably not a good idea however, as that won't handle proper escaping of double-quotes within the string and will not produce valid JSON for any such string.

One way to handle this would be to embed your string inside an object or list, so that you're not passing a raw string to Spring. However, that changes the format of your output, and really there's no good reason not to be able to return a properly-encoded JSON string if that's what you want to do. If that's what you want, the best way to handle it is via a JSON formatter such as Json or Google Gson. Here's how it might look with Gson:


public class MyController

    private static final Gson gson = new Gson();

    @RequestMapping(value = "so", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    ResponseEntity<String> so() {
        return ResponseEntity.ok(gson.toJson("This is a String"));

Skipping every other element after the first

Alternatively, you could do:

for i in range(0, len(a), 2):
    #do something

The extended slice notation is much more concise, though.

Using JQuery to check if no radio button in a group has been checked

I am using this much simple


<label class="radio"><input id="job1" type="radio" name="job" value="1" checked>New Job</label>
<label class="radio"><input id="job2" type="radio" name="job" value="2">Updating Job</label>

<button type="button" class="btn btn-primary" onclick="save();">Save</button>


 $('#save').on('click', function(e) {
    if (job1.checked)
              alert("New Job"); 
if (job2.checked)
            alert("Updating Job");


How to parse a JSON file in swift?

I also wrote a small library which is specialized for the mapping of the json response into an object structure. I am internally using the library json-swift from David Owens. Maybe it is useful for someone else.

Example Employees.json

"employees": [
    "firstName": "John",
    "lastName": "Doe",
    "age": 26
    "firstName": "Anna",
    "lastName": "Smith",
    "age": 30
    "firstName": "Peter",
    "lastName": "Jones",
    "age": 45

As next step you have to create your data model (EmplyoeeContainer and Employee).


class Employee : ROJSONObject {

    required init() {

    required init(jsonData:AnyObject) {
        super.init(jsonData: jsonData)

    var firstname:String {
        return Value<String>.get(self, key: "firstName")

    var lastname:String {
        return Value<String>.get(self, key: "lastName")            

    var age:Int {
        return Value<Int>.get(self, key: "age")


class EmployeeContainer : ROJSONObject {
    required init() {

    required init(jsonData:AnyObject) {
        super.init(jsonData: jsonData)

    lazy var employees:[Employee] = {
        return Value<[Employee]>.getArray(self, key: "employees") as [Employee]

Then to actually map the objects from the JSON response you only have to pass the data into the EmployeeContainer class as param in the constructor. It does automatically create your data model.

 var baseWebservice:BaseWebservice = BaseWebservice();

  var urlToJSON = ""

  var callbackJSON = {(status:Int, employeeContainer:EmployeeContainer) -> () in
    for employee in employeeContainer.employees {
      println("Firstname: \(employee.firstname) Lastname: \(employee.lastname) age: \(employee.age)")

  baseWebservice.get(urlToJSON, callback:callbackJSON)

The console output looks then like the following:

Firstname: John Lastname: Doe age: 26
Firstname: Anna Lastname: Smith age: 30
Firstname: Peter Lastname: Jones age: 45

How to check if a DateTime field is not null or empty?

If you declare a DateTime, then the default value is DateTime.MinValue, and hence you have to check it like this:

DateTime dat = new DateTime();

 if (dat==DateTime.MinValue)

If the DateTime is nullable, well that's a different story:

 DateTime? dat = null;

 if (!dat.HasValue)

If statement for strings in python?

Even once you fixed the mis-cased if and improper indentation in your code, it wouldn't work as you probably expected. To check a string against a set of strings, use in. Here's how you'd do it (and note that if is all lowercase and that the code within the if block is indented one level).

One approach:

if answer in ['y', 'Y', 'yes', 'Yes', 'YES']:
    print("this will do the calculation")


if answer.lower() in ['y', 'yes']:
    print("this will do the calculation")

laravel Unable to prepare route ... for serialization. Uses Closure

The Actual solution of this problem is changing first line in web.php

Just replace Welcome route with following route

Route::view('/', 'welcome');

If still getting same error than you probab

How can I change my Cygwin home folder after installation?

I did something quite simple. I did not want to change the windows 7 environment variable. So I directly edited the Cygwin.bat file.

@echo off
set HOME=C:\path\to\home
chdir C:\apps\cygwin\bin
bash --login -i

This just starts the local shell with this home directory; that is what I wanted. I am not going to remotely access this, so this worked for me.

How to set my default shell on Mac?

edit .zshrc and change it to

exec /bin/bash

or to whatever shell you might prefer. Bonus: this doesn't require root access and will work on every version of osx.

The only problem is that it doesn't read .bash_profile this way; it is only read if bash is run as an interactive login shell, you would have to include it from .bashrc with something like this:

if [[ "$OSTYPE" == "darwin"* ]]; then
    #local hack on osx.
    if [[ -f $HOME/.bash_profile ]]; then
      . $HOME/.bash_profile

Export P7b file with all the certificate chain into CER file

The selected answer didn't work for me, but it's close. I found a tutorial that worked for me and the certificate I obtained from StartCom.

  1. Open the .p7b in a text editor.
  2. Change the leader and trailer so the file looks similar to this:

    -----BEGIN PKCS7-----
    [... certificate content here ...]
    -----END PKCS7-----

For example, my StartCom certificate began with:

    -----BEGIN CERTIFICATE----- 

and ended with:

    -----END CERTIFICATE----- 
  1. Save and close the .p7b.
  2. Run the following OpenSSL command (works on Ubuntu 14.04.4, as of this writing):

    openssl pkcs7 -print_certs –in pkcs7.p7b -out pem.cer

The output is a .cer with the certificate chain.


Change Name of Import in Java, or import two classes with the same name

There is no import aliasing mechanism in Java. You cannot import two classes with the same name and use both of them unqualified.

Import one class and use the fully qualified name for the other one, i.e.

import com.text.Formatter;

private Formatter textFormatter;
private com.json.Formatter jsonFormatter;

Min width in window resizing

You can set min-width property of CSS for body tag. Since this property is not supported by IE6, you can write like:

   min-width:1000px;        /* Suppose you want minimum width of 1000px */
   width: auto !important;  /* Firefox will set width as auto */
   width:1000px;            /* As IE6 ignores !important it will set width as 1000px; */


   min-width:1000px; // Suppose you want minimum width of 1000px
   _width: expression( document.body.clientWidth > 1000 ? "1000px" : "auto" ); /* sets max-width for IE6 */

jQuery: Performing synchronous AJAX requests

As you're making a synchronous request, that should be

function getRemote() {
    return $.ajax({
        type: "GET",
        url: remote_url,
        async: false

Example -

PLEASE NOTE: Setting async property to false is deprecated and in the process of being removed (link). Many browsers including Firefox and Chrome have already started to print a warning in the console if you use this:


Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check


Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user’s experience. For more help

Create nice column output in python

You have to do this with 2 passes:

  1. get the maximum width of each column.
  2. formatting the columns using our knowledge of max width from the first pass using str.ljust() and str.rjust()

reactjs - how to set inline style of backgroundcolor?

Your quotes are in the wrong spot. Here's a simple example:

<div style={{backgroundColor: "#FF0000"}}>red</div>

Read Content from Files which are inside Zip file

If you're wondering how to get the file content from each ZipEntry it's actually quite simple. Here's a sample code:

public static void main(String[] args) throws IOException {
    ZipFile zipFile = new ZipFile("C:/");

    Enumeration<? extends ZipEntry> entries = zipFile.entries();

        ZipEntry entry = entries.nextElement();
        InputStream stream = zipFile.getInputStream(entry);

Once you have the InputStream you can read it however you want.

How to do encryption using AES in Openssl

I am trying to write a sample program to do AES encryption using Openssl.

This answer is kind of popular, so I'm going to offer something more up-to-date since OpenSSL added some modes of operation that will probably help you.

First, don't use AES_encrypt and AES_decrypt. They are low level and harder to use. Additionally, it's a software-only routine, and it will never use hardware acceleration, like AES-NI. Finally, its subject to endianess issues on some obscure platforms.

Instead, use the EVP_* interfaces. The EVP_* functions use hardware acceleration, like AES-NI, if available. And it does not suffer endianess issues on obscure platforms.

Second, you can use a mode like CBC, but the ciphertext will lack integrity and authenticity assurances. So you usually want a mode like EAX, CCM, or GCM. (Or you manually have to apply a HMAC after the encryption under a separate key.)

Third, OpenSSL has a wiki page that will probably interest you: EVP Authenticated Encryption and Decryption. It uses GCM mode.

Finally, here's the program to encrypt using AES/GCM. The OpenSSL wiki example is based on it.

#include <openssl/evp.h>
#include <openssl/aes.h>
#include <openssl/err.h>
#include <string.h>   

int main(int arc, char *argv[])

    /* Set up the key and iv. Do I need to say to not hard code these in a real application? :-) */

    /* A 256 bit key */
    static const unsigned char key[] = "01234567890123456789012345678901";

    /* A 128 bit IV */
    static const unsigned char iv[] = "0123456789012345";

    /* Message to be encrypted */
    unsigned char plaintext[] = "The quick brown fox jumps over the lazy dog";

    /* Some additional data to be authenticated */
    static const unsigned char aad[] = "Some AAD data";

    /* Buffer for ciphertext. Ensure the buffer is long enough for the
     * ciphertext which may be longer than the plaintext, dependant on the
     * algorithm and mode
    unsigned char ciphertext[128];

    /* Buffer for the decrypted text */
    unsigned char decryptedtext[128];

    /* Buffer for the tag */
    unsigned char tag[16];

    int decryptedtext_len = 0, ciphertext_len = 0;

    /* Encrypt the plaintext */
    ciphertext_len = encrypt(plaintext, strlen(plaintext), aad, strlen(aad), key, iv, ciphertext, tag);

    /* Do something useful with the ciphertext here */
    printf("Ciphertext is:\n");
    BIO_dump_fp(stdout, ciphertext, ciphertext_len);
    printf("Tag is:\n");
    BIO_dump_fp(stdout, tag, 14);

    /* Mess with stuff */
    /* ciphertext[0] ^= 1; */
    /* tag[0] ^= 1; */

    /* Decrypt the ciphertext */
    decryptedtext_len = decrypt(ciphertext, ciphertext_len, aad, strlen(aad), tag, key, iv, decryptedtext);

    if(decryptedtext_len < 0)
        /* Verify error */
        printf("Decrypted text failed to verify\n");
        /* Add a NULL terminator. We are expecting printable text */
        decryptedtext[decryptedtext_len] = '\0';

        /* Show the decrypted text */
        printf("Decrypted text is:\n");
        printf("%s\n", decryptedtext);

    /* Remove error strings */

    return 0;

void handleErrors(void)
    unsigned long errCode;

    printf("An error occurred\n");
    while(errCode = ERR_get_error())
        char *err = ERR_error_string(errCode, NULL);
        printf("%s\n", err);

int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *aad,
            int aad_len, unsigned char *key, unsigned char *iv,
            unsigned char *ciphertext, unsigned char *tag)
    int len = 0, ciphertext_len = 0;

    /* Create and initialise the context */
    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();

    /* Initialise the encryption operation. */
    if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))

    /* Set IV length if default 12 bytes (96 bits) is not appropriate */
    if(1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, 16, NULL))

    /* Initialise key and IV */
    if(1 != EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv)) handleErrors();

    /* Provide any AAD data. This can be called zero or more times as
     * required
    if(aad && aad_len > 0)
        if(1 != EVP_EncryptUpdate(ctx, NULL, &len, aad, aad_len))

    /* Provide the message to be encrypted, and obtain the encrypted output.
     * EVP_EncryptUpdate can be called multiple times if necessary
        if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))

        ciphertext_len = len;

    /* Finalise the encryption. Normally ciphertext bytes may be written at
     * this stage, but this does not occur in GCM mode
    if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len)) handleErrors();
    ciphertext_len += len;

    /* Get the tag */
    if(1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, tag))

    /* Clean up */

    return ciphertext_len;

int decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *aad,
            int aad_len, unsigned char *tag, unsigned char *key, unsigned char *iv,
            unsigned char *plaintext)
    int len = 0, plaintext_len = 0, ret;

    /* Create and initialise the context */
    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();

    /* Initialise the decryption operation. */
    if(!EVP_DecryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))

    /* Set IV length. Not necessary if this is 12 bytes (96 bits) */

    /* Initialise key and IV */
    if(!EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv)) handleErrors();

    /* Provide any AAD data. This can be called zero or more times as
     * required
    if(aad && aad_len > 0)
        if(!EVP_DecryptUpdate(ctx, NULL, &len, aad, aad_len))

    /* Provide the message to be decrypted, and obtain the plaintext output.
     * EVP_DecryptUpdate can be called multiple times if necessary
        if(!EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))

        plaintext_len = len;

    /* Set expected tag value. Works in OpenSSL 1.0.1d and later */
    if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16, tag))

    /* Finalise the decryption. A positive return value indicates success,
     * anything else is a failure - the plaintext is not trustworthy.
    ret = EVP_DecryptFinal_ex(ctx, plaintext + len, &len);

    /* Clean up */

    if(ret > 0)
        /* Success */
        plaintext_len += len;
        return plaintext_len;
        /* Verify failed */
        return -1;

In jQuery how can I set "top,left" properties of an element with position values relative to the parent and not the document?

Refreshing my memory on setting position, I'm coming to this so late I don't know if anyone else will see it, but --

I don't like setting position using css(), though often it's fine. I think the best bet is to use jQuery UI's position() setter as noted by xdazz. However if jQuery UI is, for some reason, not an option (yet jQuery is), I prefer this:

const leftOffset = 200;
const topOffset = 200;
let $div = $("#mydiv");
let baseOffset = $div.offsetParent().offset();
  left: baseOffset.left + leftOffset,
  top: + topOffset

This has the advantage of not arbitrarily setting $div's parent to relative positioning (what if $div's parent was, itself, absolute positioned inside something else?). I think the only major edge case is if $div doesn't have any offsetParent, not sure if it would return document, null, or something else entirely.

offsetParent has been available since jQuery 1.2.6, sometime in 2008, so this technique works now and when the original question was asked.

How do I plot only a table in Matplotlib?

If you just wanted to change the example and put the table at the top, then loc='top' in the table declaration is what you need,

the_table = ax.table(cellText=cell_text,

Then adjusting the plot with,

plt.subplots_adjust(left=0.2, top=0.8)

A more flexible option is to put the table in its own axis using subplots,

import numpy as np
import matplotlib.pyplot as plt

fig, axs =plt.subplots(2,1)
clust_data = np.random.random((10,3))
collabel=("col 1", "col 2", "col 3")
the_table = axs[0].table(cellText=clust_data,colLabels=collabel,loc='center')


which looks like this,

enter image description here

You are then free to adjust the locations of the axis as required.

how to implement regions/code collapse in javascript

On VS 2012 and VS 2015 install WebEssentials plugin and you will able to do so.

How do you get a directory listing in C?

Directory listing varies greatly according to the OS/platform under consideration. This is because, various Operating systems using their own internal system calls to achieve this.

A solution to this problem would be to look for a library which masks this problem and portable. Unfortunately, there is no solution that works on all platforms flawlessly.

On POSIX compatible systems, you could use the library to achieve this using the code posted by Clayton (which is referenced originally from the Advanced Programming under UNIX book by W. Richard Stevens). this solution will work under *NIX systems and would also work on Windows if you have Cygwin installed.

Alternatively, you could write a code to detect the underlying OS and then call the appropriate directory listing function which would hold the 'proper' way of listing the directory structure under that OS.

Kubernetes Pod fails with CrashLoopBackOff

I ran into the same error.

NAME         READY   STATUS             RESTARTS   AGE
pod/webapp   0/1     CrashLoopBackOff   5          47h

My problem was that I was trying to run two different pods with the same metadata name.

kind: Pod metadata: name: webapp labels: ...

To find all the names of your pods run: kubectl get pods

webapp       1/1     Running   15         47h

then I changed the conflicting pod name and everything worked just fine.

NAME                 READY   STATUS    RESTARTS   AGE
webapp               1/1     Running   17         2d
webapp-release-0-5   1/1     Running   0          13m

How can I create a self-signed cert for localhost?

you could try mkcert.

macos: brew install mkcert

Difference Between Schema / Database in MySQL

Microsoft SQL Server for instance, Schemas refer to a single user and is another level of a container in the order of indicating the server, database, schema, tables, and objects.

For example, when you are intending to update dbo.table_a and the syntax isn't full qualified such as UPDATE table.a the DBMS can't decide to use the intended table. Essentially by default the DBMS will utilize myuser.table_a

How to create an on/off switch with Javascript/CSS?

Outline: Create two elements: a slider/switch and a trough as a parent of the slider. To toggle the state, switch the slider element between an "on" and an "off" class. In the style for one class, set "left" to 0 and leave "right" the default; for the other class, do the opposite:

<style type="text/css">
.toggleSwitch {
    width: ...;
    height: ...;
    /* add other styling as appropriate to position element */
    position: relative;
.slider {
    background-image: url(...);
    position: absolute;
    width: ...;
    height: ...;
.slider.on {
    right: 0;
} {
    left: 0;
<script type="text/javascript">
function replaceClass(elt, oldClass, newClass) {
    var oldRE = RegExp('\\b'+oldClass+'\\b');
    elt.className = elt.className.replace(oldRE, newClass);
function toggle(elt, on, off) {
    var onRE = RegExp('\\b'+on+'\\b');
    if (onRE.test(elt.className)) {
        elt.className = elt.className.replace(onRE, off);
    } else {
        replaceClass(elt, off, on);
<div class="toggleSwitch" onclick="toggle(this.firstChild, 'on', 'off');"><div class="slider off" /></div>

Alternatively, just set the background image for the "on" and "off" states, which is a much easier approach than mucking about with positioning.

How to get cookie's expire time

It seems there's a list of all cookies sent to browser in array returned by php's headers_list() which among other data returns "Set-Cookie" elements as follows:

Set-Cookie: cooke_name=cookie_value; expires=expiration_time; Max-Age=age; path=path; domain=domain

This way you can also get deleted ones since their value is deleted:

Set-Cookie: cooke_name=deleted; expires=expiration_time; Max-Age=age; path=path; domain=domain

From there on it's easy to retrieve expiration time or age for particular cookie. Keep in mind though that this array is probably available only AFTER actual call to setcookie() has been made so it's valid for script that has already finished it's job. I haven't tested this in some other way(s) since this worked just fine for me.

This is rather old topic and I'm not sure if this is valid for all php builds but I thought it might be helpfull.

For more info see:

Background color on input type=button :hover state sticks in IE

There might be a fix to <input type="button"> - but if there is, I don't know it.

Otherwise, a good option seems to be to replace it with a carefully styled a element.


.button {
    background-color: #E3E1B8; 
    padding: 2px 4px;
    font: 13px sans-serif;
    text-decoration: none;
    border: 1px solid #000;
    border-color: #aaa #444 #444 #aaa;
    color: #000

Upsides include that the a element will style consistently between different (older) versions of Internet Explorer without any extra work, and I think my link looks nicer than that button :)

Manually type in a value in a "Select" / Drop-down HTML list?

It can be done now with HTML5

See this post here HTML select form with option to enter custom value

<input type="text" list="cars" />
<datalist id="cars">

Spring .properties file: get element as an Array

If you need to pass the asterisk symbol, you have to wrap it with quotes.

In my case, I need to configure cors for websockets. So, I decided to put cors urls into application.yml. For prod env I'll use specific urls, but for dev it's ok to use just *.

In yml file I have:

  cors: "*"

In Config class I have:

private String[] cors;

How to use OR condition in a JavaScript IF statement?

here is my example:

 console.log("Too Bad!");   

This says that if the answer is Yes yes or YeS than the same thing will happen

Get Root Directory Path of a PHP project

For PHP >= 5.3.0 try

PHP magic constants.


And make your path relative.

For PHP < 5.3.0 try


Getting value of selected item in list box as string

You can Use This One To get the selected ListItme Name ::

String selectedItem = ((ListBoxItem)ListBox.SelectedItem).Name.ToString();

Make sure that Your each ListBoxItem have a Name property

Get the name of an object's type

For of those of you reading this and want a simple solution that works fairly well and has been tested:

const getTypeName = (thing) => {
  const name = typeof thing
  if (name !== 'object') return name
  if (thing instanceof Error) return 'error'
  if (!thing) return 'null'
  return ({})\s([a-zA-Z]+)/)[1].toLowerCase()

To get insight on why this works, checkout the polyfill documentation for Array.isArray():

What does jQuery.fn mean?

In jQuery, the fn property is just an alias to the prototype property.

The jQuery identifier (or $) is just a constructor function, and all instances created with it, inherit from the constructor's prototype.

A simple constructor function:

function Test() {
  this.a = 'a';
Test.prototype.b = 'b';

var test = new Test(); 
test.a; // "a", own property
test.b; // "b", inherited property

A simple structure that resembles the architecture of jQuery:

(function() {
  var foo = function(arg) { // core constructor
    // ensure to use the `new` operator
    if (!(this instanceof foo))
      return new foo(arg);
    // store an argument for this example
    this.myArg = arg;

  // create `fn` alias to `prototype` property
  foo.fn = foo.prototype = {
    init: function () {/*...*/}

  // expose the library = foo;

// Extension:

foo.fn.myPlugin = function () {
  return this; // return `this` for chainability

foo("bar").myPlugin(); // alerts "bar"

Java 8 lambdas, Function.identity() or t->t

From the JDK source:

static <T> Function<T, T> identity() {
    return t -> t;

So, no, as long as it is syntactically correct.

convert a list of objects from one type to another using lambda expression

If you know you want to convert from List<T1> to List<T2> then List<T>.ConvertAll will be slightly more efficient than Select/ToList because it knows the exact size to start with:

target = orig.ConvertAll(x => new TargetType { SomeValue = x.SomeValue });

In the more general case when you only know about the source as an IEnumerable<T>, using Select/ToList is the way to go. You could also argue that in a world with LINQ, it's more idiomatic to start with... but it's worth at least being aware of the ConvertAll option.

How to make <input type="file"/> accept only these types?

Use accept attribute with the MIME_type as values

<input type="file" accept="image/gif, image/jpeg" />

jQuery .get error response function?

You can get detail error by using responseText property.

error: function(xhr, status, error) {
alert("An AJAX error occured: " + status + "\nError: " + error + "\nError detail: " + xhr.responseText);

Iterate through the fields of a struct in Go

If you want to Iterate through the Fields and Values of a struct then you can use the below Go code as a reference.

package main

import (

type Student struct {
    Fname  string
    Lname  string
    City   string
    Mobile int64

func main() {
    s := Student{"Chetan", "Kumar", "Bangalore", 7777777777}
    v := reflect.ValueOf(s)
    typeOfS := v.Type()

    for i := 0; i< v.NumField(); i++ {
        fmt.Printf("Field: %s\tValue: %v\n", typeOfS.Field(i).Name, v.Field(i).Interface())

Run in playground

Note: If the Fields in your struct are not exported then the v.Field(i).Interface() will give panic panic: reflect.Value.Interface: cannot return value obtained from unexported field or method.

How to dynamically remove items from ListView on a button click?


And create Event item_delete_handler,

Search and get a line in Python

you mentioned "entire line" , so i assumed mystring is the entire line.

if "token" in mystring:

however if you want to just get "token qwerty",

>>> mystring="""
...     qwertyuiop
...     asdfghjkl
...     zxcvbnm
...     token qwerty
...     asdfghjklñ
... """
>>> for item in mystring.split("\n"):
...  if "token" in item:
...     print (item.strip())
token qwerty

Python vs Cpython

A programming language implementation is a system for executing computer programs.

There are two general approaches to programming language implementation:

  • Interpretation: An interpreter takes as input a program in some language, and performs the actions written in that language on some machine.
  • Compilation: A compiler takes as input a program in some language, and translates that program into some other language, which may serve as input to another interpreter or another compiler.

Python is an interpreted high-level programming language created by Guido van Rossum in 1991.

CPython is reference version of the Python computing language, which is written in C created by Guido van Rossum too.

Other list of Python Implementations


Force an Android activity to always use landscape mode

In my OnCreate(Bundle), I generally do the following:


Error handling with try and catch in Laravel

You are inside a namespace so you should use \Exception to specify the global namespace:

try {


} catch (\Exception $e) {

    return $e->getMessage();

In your code you've used catch (Exception $e) so Exception is being searched in/as:


Since there is no Exception class inside App\Services\PayUService so it's not being triggered. Alternatively, you can use a use statement at the top of your class like use Exception; and then you can use catch (Exception $e).

Unit testing void methods?

As always: test what the method is supposed to do!

Should it change global state (uuh, code smell!) somewhere?

Should it call into an interface?

Should it throw an exception when called with the wrong parameters?

Should it throw no exception when called with the right parameters?

Should it ...?

What's the quickest way to multiply multiple cells by another number?

  1. Enter the multiplier in a cell
  2. Copy that cell to the clipboard
  3. Select the range you want to multiply by the multiplier
  4. (Excel 2003 or earlier) Choose Edit | Paste Special | Multiply

    (Excel 2007 or later) Click on the Paste down arrow | Paste Special | Multiply

How do I include a pipe | in my linux find -exec command?

You can also pipe to a while loop that can do multiple actions on the file which find locates. So here is one for looking in jar archives for a given java class file in folder with a large distro of jar files

find /usr/lib/eclipse/plugins -type f -name \*.jar | while read jar; do echo $jar; jar tf $jar | fgrep IObservableList ; done

the key point being that the while loop contains multiple commands referencing the passed in file name separated by semicolon and these commands can include pipes. So in that example I echo the name of the matching file then list what is in the archive filtering for a given class name. The output looks like:

/usr/lib/eclipse/plugins/org.eclipse.core.contenttype.source_3.4.1.R35x_v20090826-0451.jar /usr/lib/eclipse/plugins/org.eclipse.core.databinding.observable_1.2.0.M20090902-0800.jar org/eclipse/core/databinding/observable/list/IObservableList.class /usr/lib/eclipse/plugins/ /usr/lib/eclipse/plugins/org.eclipse.jdt.apt.core.source_3.3.202.R35x_v20091130-2300.jar /usr/lib/eclipse/plugins/org.eclipse.cvs.source_1.0.400.v201002111343.jar /usr/lib/eclipse/plugins/

in my bash shell (xubuntu10.04/xfce) it really does make the matched classname bold as the fgrep highlights the matched string; this makes it really easy to scan down the list of hundreds of jar files that were searched and easily see any matches.

on windows you can do the same thing with:

for /R %j in (*.jar) do @echo %j & @jar tf %j | findstr IObservableList

note that in that on windows the command separator is '&' not ';' and that the '@' suppresses the echo of the command to give a tidy output just like the linux find output above; although findstr is not make the matched string bold so you have to look a bit closer at the output to see the matched class name. It turns out that the windows 'for' command knows quite a few tricks such as looping through text files...


Item frequency count in Python

I happened to work on some Spark exercise, here is my solution.

tokens = ['quick', 'brown', 'fox', 'jumps', 'lazy', 'dog']

print {n: float(tokens.count(n))/float(len(tokens)) for n in tokens}

**#output of the above **

{'brown': 0.16666666666666666, 'lazy': 0.16666666666666666, 'jumps': 0.16666666666666666, 'fox': 0.16666666666666666, 'dog': 0.16666666666666666, 'quick': 0.16666666666666666}

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

just add in build.gradle

compile 'com.parse.bolts:bolts-android:1.+'

compile 'com.parse:parse-android:1.11.0'

and sync Project with Gradle Files enter image description here But Don't Add The parse Jar in libs :) OKK

How to get Javascript Select box's selected text

In order to get the value of the selected item you can do the following:


Here the different options of the select are accessed, and the SelectedIndex is used to choose the selected one, then its text is being accessed.

Read more about the select DOM here.

How do I register a DLL file on Windows 7 64-bit?

Open the start menu and type cmd into the search box Hold Ctrl + Shift and press Enter

This runs the Command Prompt in Administrator mode.

Now type: regsvr32 MyComobject.dll

.NET obfuscation tools/strategy

We have a multi tier app with an and winform interface that also supports remoting. I've had no problems with using any obfuscator with the exception of the encrypting type which generates a loader which can be problematic in all sorts of unexpected ways and just not worth it in my opinion. Actually my advice would be more along the lines of "Avoid encrypting loader type obfuscators like the plague". :)

In my experience any obfuscator will work fine with any aspect of .net including and remoting, you just have to become intimate with the settings and learn how far you can push it in which areas of your code. And take the time to attempt reverse engineering on what you get and see how it works with the various settings.

We used several over the years in our commercial apps and settled on Spices obfuscator from because the price is right, it does the job and they have good support though we really haven't needed the support in years anymore but to be honest I don't think it really matters which obfuscator you use, the issues and learning curve are all the same if you want to have it work properly with remoting and

As others have mentioned all you're really doing is the equivalent of a padlock, keeping otherwise honest people out and or making it harder to simply recompile an app.

Licensing is usually the key area for most people and you should definitely be using some kind of digitally signed certificate system for licensing anyway. Your biggest loss will come from casual sharing of licenses if you don't have a smart system in place, the people that break the licensing system were never going to buy in the first place.

It's really easy to take this too far and have a negative impact on your customers and your business, do what is simple and reasonable and then don't worry about it.

getFilesDir() vs Environment.getDataDirectory()

From the HERE and HERE

public File getFilesDir ()

Returns the absolute path to the directory on the filesystem where files created with openFileOutput(String, int) are stored.

public static File getExternalStorageDirectory ()

Return the primary external storage directory. This directory may not currently be accessible if it has been mounted by the user on their computer, has been removed from the device, or some other problem has happened. You can determine its current state with getExternalStorageState().

Note: don't be confused by the word "external" here. This directory can better be thought as media/shared storage. It is a filesystem that can hold a relatively large amount of data and that is shared across all applications (does not enforce permissions). Traditionally this is an SD card, but it may also be implemented as built-in storage in a device that is distinct from the protected internal storage and can be mounted as a filesystem on a computer.

On devices with multiple users (as described by UserManager), each user has their own isolated external storage. Applications only have access to the external storage for the user they're running as.

If you want to get your application path use getFilesDir() which will give you path /data/data/your package/files

You can get the path using the Environment var of your data/package using the

getExternalFilesDir(Environment.getDataDirectory().getAbsolutePath()).getAbsolutePath(); which will return the path from the root directory of your external storage as /storage/sdcard/Android/data/your pacakge/files/data

To access the external resources you have to provide the permission of WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE in your manifest.

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

Check out the Best Documentation to get the paths of direcorty

PHP Fatal error: Call to undefined function mssql_connect()

I have just tried to install that extension on my dev server.

First, make sure that the extension is correctly enabled. Your phpinfo() output doesn't seem complete.

If it is indeed installed properly, your phpinfo() should have a section that looks like this: enter image description here

If you do not get that section in your phpinfo(). Make sure that you are using the right version. There are both non-thread-safe and thread-safe versions of the extension.

Finally, check your extension_dir setting. By default it's this: extension_dir = "ext", for most of the time it works fine, but if it doesn't try: extension_dir = "C:\PHP\ext".


EDIT given new info:

You are using the wrong function. mssql_connect() is part of the Mssql extension. You are using microsoft's extension, so use sqlsrv_connect(), for the API for the microsoft driver, look at SQLSRV_Help.chm which should be extracted to your ext directory when you extracted the extension.

How to get Linux console window width in Python


import console
(width, height) = console.getTerminalSize()

print "Your terminal's width is: %d" % width

EDIT: oh, I'm sorry. That's not a python standard lib one, here's the source of (I don't know where it's from).

The module seems to work like that: It checks if termcap is available, when yes. It uses that; if no it checks whether the terminal supports a special ioctl call and that does not work, too, it checks for the environment variables some shells export for that. This will probably work on UNIX only.

def getTerminalSize():
    import os
    env = os.environ
    def ioctl_GWINSZ(fd):
            import fcntl, termios, struct, os
            cr = struct.unpack('hh', fcntl.ioctl(fd, termios.TIOCGWINSZ,
        return cr
    cr = ioctl_GWINSZ(0) or ioctl_GWINSZ(1) or ioctl_GWINSZ(2)
    if not cr:
            fd =, os.O_RDONLY)
            cr = ioctl_GWINSZ(fd)
    if not cr:
        cr = (env.get('LINES', 25), env.get('COLUMNS', 80))

        ### Use get(key[, default]) instead of a try/catch
        #    cr = (env['LINES'], env['COLUMNS'])
        #    cr = (25, 80)
    return int(cr[1]), int(cr[0])

What is the role of "Flatten" in Keras?

short read:

Flattening a tensor means to remove all of the dimensions except for one. This is exactly what the Flatten layer do.

long read:

If we take the original model (with the Flatten layer) created in consideration we can get the following model summary:

Layer (type)                 Output Shape              Param #   
D16 (Dense)                  (None, 3, 16)             48        
A (Activation)               (None, 3, 16)             0         
F (Flatten)                  (None, 48)                0         
D4 (Dense)                   (None, 4)                 196       
Total params: 244
Trainable params: 244
Non-trainable params: 0

For this summary the next image will hopefully provide little more sense on the input and output sizes for each layer.

The output shape for the Flatten layer as you can read is (None, 48). Here is the tip. You should read it (1, 48) or (2, 48) or ... or (16, 48) ... or (32, 48), ...

In fact, None on that position means any batch size. For the inputs to recall, the first dimension means the batch size and the second means the number of input features.

The role of the Flatten layer in Keras is super simple:

A flatten operation on a tensor reshapes the tensor to have the shape that is equal to the number of elements contained in tensor non including the batch dimension.

enter image description here

Note: I used the model.summary() method to provide the output shape and parameter details.

How to delete directory content in Java?

All files must be delete from the directory before it is deleted.

There are third party libraries that have a lot of common utilities, including ones that does that for you:

how to hide <li> bullets in navigation menu and footer links BUT show them for listing items

You need to define a class for the bullets you want to hide. For examples

.no-bullets {
    list-style-type: none;

Then apply it to the list you want hidden bullets:

<ul class="no-bullets">

All other lists (without a specific class) will show the bulltets as usual.

What are Aggregates and PODs and how/why are they special?

What has changed for C++14

We can refer to the Draft C++14 standard for reference.


This is covered in section 8.5.1 Aggregates which gives us the following definition:

An aggregate is an array or a class (Clause 9) with no user-provided constructors (12.1), no private or protected non-static data members (Clause 11), no base classes (Clause 10), and no virtual functions (10.3).

The only change is now adding in-class member initializers does not make a class a non-aggregate. So the following example from C++11 aggregate initialization for classes with member in-place initializers:

struct A
  int a = 3;
  int b = 3;

was not an aggregate in C++11 but it is in C++14. This change is covered in N3605: Member initializers and aggregates, which has the following abstract:

Bjarne Stroustrup and Richard Smith raised an issue about aggregate initialization and member-initializers not working together. This paper proposes to fix the issue by adopting Smith's proposed wording that removes a restriction that aggregates can't have member-initializers.

POD stays the same

The definition for POD(plain old data) struct is covered in section 9 Classes which says:

A POD struct110 is a non-union class that is both a trivial class and a standard-layout class, and has no non-static data members of type non-POD struct, non-POD union (or array of such types). Similarly, a POD union is a union that is both a trivial class and a standard-layout class, and has no non-static data members of type non-POD struct, non-POD union (or array of such types). A POD class is a class that is either a POD struct or a POD union.

which is the same wording as C++11.

Standard-Layout Changes for C++14

As noted in the comments pod relies on the definition of standard-layout and that did change for C++14 but this was via defect reports that were applied to C++14 after the fact.

There were three DRs:

So standard-layout went from this Pre C++14:

A standard-layout class is a class that:

  • (7.1) has no non-static data members of type non-standard-layout class (or array of such types) or reference,
  • (7.2) has no virtual functions ([class.virtual]) and no virtual base classes ([class.mi]),
  • (7.3) has the same access control (Clause [class.access]) for all non-static data members,
  • (7.4) has no non-standard-layout base classes,
  • (7.5) either has no non-static data members in the most derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and
  • (7.6) has no base classes of the same type as the first non-static data member.109

To this in C++14:

A class S is a standard-layout class if it:

  • (3.1) has no non-static data members of type non-standard-layout class (or array of such types) or reference,
  • (3.2) has no virtual functions and no virtual base classes,
  • (3.3) has the same access control for all non-static data members,
  • (3.4) has no non-standard-layout base classes,
  • (3.5) has at most one base class subobject of any given type,
  • (3.6) has all non-static data members and bit-fields in the class and its base classes first declared in the same class, and
  • (3.7) has no element of the set M(S) of types as a base class, where for any type X, M(X) is defined as follows.104 [ Note: M(X) is the set of the types of all non-base-class subobjects that may be at a zero offset in X. — end note ]
    • (3.7.1) If X is a non-union class type with no (possibly inherited) non-static data members, the set M(X) is empty.
    • (3.7.2) If X is a non-union class type with a non-static data member of type X0 that is either of zero size or is the first non-static data member of X (where said member may be an anonymous union), the set M(X) consists of X0 and the elements of M(X0).
    • (3.7.3) If X is a union type, the set M(X) is the union of all M(Ui) and the set containing all Ui, where each Ui is the type of the ith non-static data member of X.
    • (3.7.4) If X is an array type with element type Xe, the set M(X) consists of Xe and the elements of M(Xe).
    • (3.7.5) If X is a non-class, non-array type, the set M(X) is empty.

How to make an HTML back link?

The easiest way is to use history.go(-1);

Try this:

<a href="#" onclick="history.go(-1)">Go Back</a>

How do I revert to a previous package in Anaconda?

For the case that you wish to revert a recently installed package that made several changes to dependencies (such as tensorflow), you can "roll back" to an earlier installation state via the following method:

conda list --revisions
conda install --revision [revision number]

The first command shows previous installation revisions (with dependencies) and the second reverts to whichever revision number you specify.

Note that if you wish to (re)install a later revision, you may have to sequentially reinstall all intermediate versions. If you had been at revision 23, reinstalled revision 20 and wish to return, you may have to run each:

conda install --revision 21
conda install --revision 22
conda install --revision 23

Test if remote TCP port is open from a shell script

I needed a more flexible solution for working on multiple git repositories so I wrote the following sh code based on 1 and 2. You can use your server address instead of and your port in replace of 22.
nc -z -v -w5 $SERVER $PORT

#Do whatever you want

if [  "$result1" != 0 ]; then
  echo  'port 22 is closed'
  echo 'port 22 is open'

AngularJS - ng-if check string empty value

Probably your is undefined if you don't have a photo attribute on item in the first place and thus undefined != ''. But if you'd put some code to show how you provide values to item, it would help.

PS: Sorry to post this as an answer (I rather think it's more of a comment), but I don't have enough reputation yet.

"Use of undeclared type" in Swift, even though type is internal, and exists in same module

I tried many of the solutions offered here, but eventually deleted the file and created it again, and Xcode was mollified :/

Python requests library how to pass Authorization header with single token

i founded here, its ok with me for linkedin: so my code with with linkedin login here:

ref = ''
headers = {"content-type": "application/json; charset=UTF-8",'Authorization':'Bearer {}'.format(access_token)}
Linkedin_user_info = requests.get(ref1, headers=headers).json()

How do I clear my local working directory in Git?

All the answers so far retain local commits. If you're really serious, you can discard all local commits and all local edits by doing:

git reset --hard origin/branchname

For example:

git reset --hard origin/master

This makes your local repository exactly match the state of the origin (other than untracked files).

If you accidentally did this after just reading the command, and not what it does :), use git reflog to find your old commits.

How to include js file in another js file?

You need to write a document.write object:

document.write('<script type="text/javascript" src="file.js" ></script>');

and place it in your main javascript file

C# Parsing JSON array of objects

Use NewtonSoft JSON.Net library.

dynamic obj = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonString);

Hope this helps.

Items in JSON object are out of order using "json.dumps"?

Both Python dict (before Python 3.7) and JSON object are unordered collections. You could pass sort_keys parameter, to sort the keys:

>>> import json
>>> json.dumps({'a': 1, 'b': 2})
'{"b": 2, "a": 1}'
>>> json.dumps({'a': 1, 'b': 2}, sort_keys=True)
'{"a": 1, "b": 2}'

If you need a particular order; you could use collections.OrderedDict:

>>> from collections import OrderedDict
>>> json.dumps(OrderedDict([("a", 1), ("b", 2)]))
'{"a": 1, "b": 2}'
>>> json.dumps(OrderedDict([("b", 2), ("a", 1)]))
'{"b": 2, "a": 1}'

Since Python 3.6, the keyword argument order is preserved and the above can be rewritten using a nicer syntax:

>>> json.dumps(OrderedDict(a=1, b=2))
'{"a": 1, "b": 2}'
>>> json.dumps(OrderedDict(b=2, a=1))
'{"b": 2, "a": 1}'

See PEP 468 – Preserving Keyword Argument Order.

If your input is given as JSON then to preserve the order (to get OrderedDict), you could pass object_pair_hook, as suggested by @Fred Yankowski:

>>> json.loads('{"a": 1, "b": 2}', object_pairs_hook=OrderedDict)
OrderedDict([('a', 1), ('b', 2)])
>>> json.loads('{"b": 2, "a": 1}', object_pairs_hook=OrderedDict)
OrderedDict([('b', 2), ('a', 1)])

Use dynamic variable names in JavaScript

use Object is great too.

var a=123
var b=234
var temp = {"a":a,"b":b}

React Native Change Default iOS Simulator Device

You can create an alias at your ~/.bash_profile file:

alias rn-ios="react-native run-ios --simulator \"iPhone 5s (10.0)\""

And then run react-native using the created alias:

$ rn-ios

How to check if a variable is both null and /or undefined in JavaScript

A variable cannot be both null and undefined at the same time. However, the direct answer to your question is:

if (variable != null)

One =, not two.

There are two special clauses in the "abstract equality comparison algorithm" in the JavaScript spec devoted to the case of one operand being null and the other being undefined, and the result is true for == and false for !=. Thus if the value of the variable is undefined, it's not != null, and if it's not null, it's obviously not != null.

Now, the case of an identifier not being defined at all, either as a var or let, as a function parameter, or as a property of the global context is different. A reference to such an identifier is treated as an error at runtime. You could attempt a reference and catch the error:

var isDefined = false;
try {
  isDefined = true;
catch (x) {}

I would personally consider that a questionable practice however. For global symbols that may or may be there based on the presence or absence of some other library, or some similar situation, you can test for a window property (in browser JavaScript):

var isJqueryAvailable = window.jQuery != null;


var isJqueryAvailable = "jQuery" in window;

$rootScope.$broadcast vs. $scope.$emit

They are not doing the same job: $emit dispatches an event upwards through the scope hierarchy, while $broadcast dispatches an event downwards to all child scopes.

Render Partial View Using jQuery in ASP.NET MVC

I did it like this.


Details Method:

public IActionResult Details()

            return PartialView("Your Partial View");

Remove all special characters from a string

Here, check out this function:

function seo_friendly_url($string){
    $string = str_replace(array('[\', \']'), '', $string);
    $string = preg_replace('/\[.*\]/U', '', $string);
    $string = preg_replace('/&(amp;)?#?[a-z0-9]+;/i', '-', $string);
    $string = htmlentities($string, ENT_COMPAT, 'utf-8');
    $string = preg_replace('/&([a-z])(acute|uml|circ|grave|ring|cedil|slash|tilde|caron|lig|quot|rsquo);/i', '\\1', $string );
    $string = preg_replace(array('/[^a-z0-9]/i', '/[-]+/') , '-', $string);
    return strtolower(trim($string, '-'));

php date validation

I know this is an older post, but I've developed the following function for validating a date:

function IsDateTime($aDateTime) {
    try {
        $fTime = new DateTime($aDateTime);
        $fTime->format('m/d/Y H:i:s');
        return true;
    catch (Exception $e) {
        return false;

SQL Inner Join On Null Values

Basically you want to join two tables together where their QID columns are both not null, correct? However, you aren't enforcing any other conditions, such as that the two QID values (which seems strange to me, but ok). Something as simple as the following (tested in MySQL) seems to do what you want:


This gives you every non-null row in Y joined to every non-null row in X.

Update: Rico says he also wants the rows with NULL values, why not just:


C++ passing an array pointer as a function argument

You're over-complicating it - it just needs to be:

void generateArray(int *a, int si)
    for (int j = 0; j < si; j++)
        a[j] = rand() % 9;

int main()
    const int size=5;
    int a[size];

    generateArray(a, size);

    return 0;

When you pass an array as a parameter to a function it decays to a pointer to the first element of the array. So there is normally never a need to pass a pointer to an array.

Simple 3x3 matrix inverse code (C++)

I have just created a QMatrix class. It uses the built in vector > container. QMatrix.h It uses the Jordan-Gauss method to compute the inverse of a square matrix.

You can use it as follows:

#include "QMatrix.h"
#include <iostream>

int main(){
QMatrix<double> A(3,3,true);
QMatrix<double> Result = A.inverse()*A; //should give the idendity matrix

std::cout<<Result<<std::endl; // for checking
return 0;

The inverse function is implemented as follows:

Given a class with the following fields:

template<class T> class QMatrix{
int rows, cols;
std::vector<std::vector<T> > A;

the inverse() function:

template<class T> 
QMatrix<T> QMatrix<T>:: inverse(){
Identity<T> Id(rows); //the Identity Matrix as a subclass of QMatrix.
QMatrix<T> Result = *this; // making a copy and transforming it to the Identity matrix
T epsilon = 0.000001;
for(int i=0;i<rows;++i){
    //check if Result(i,i)==0, if true, switch the row with another

    for(int j=i;j<rows;++j){
        if(std::abs(Result(j,j))<epsilon) { //uses Overloading()(int int) to extract element from Result Matrix
            Result.replace_rows(i,j+1); //switches rows i with j+1
        else break;
    // main part, making a triangular matrix
    Result(i)=Result(i)*(1.0/Result(i,i));  // Using overloading ()(int) to get a row form the matrix
    for(int j=i+1;j<rows;++j){
        T temp = Result(j,i);
        Result(j) = Result(j) - Result(i)*temp;
        Id(j) = Id(j) - Id(i)*temp; //doing the same operations to the identity matrix
        Result(j,i)=0; //not necessary, but looks nicer than 10^-15

// solving a triangular matrix 
for(int i=rows-1;i>0;--i){
    for(int j=i-1;j>=0;--j){
        T temp = Result(j,i);
        Id(j) = Id(j) - temp*Id(i);

return Id;

Disable a Maven plugin defined in a parent POM

The thread is old, but maybe someone is still interested. The shortest form I found is further improvement on the example from ?lex and bmargulies. The execution tag will look like:


2 points I want to highlight:

  1. phase is set to nothing, which looks less hacky than 'none', though still a hack.
  2. id must be the same as execution you want to override. If you don't specify id for execution, Maven will do it implicitly (in a way not expected intuitively by you).

After posting found it is already in stackoverflow: In a Maven multi-module project, how can I disable a plugin in one child?

Python error message io.UnsupportedOperation: not readable

You are opening the file as "w", which stands for writable.

Using "w" you won't be able to read the file. Use the following instead:

file = open("File.txt","r")

Additionally, here are the other options:

"r"   Opens a file for reading only.
"r+"  Opens a file for both reading and writing.
"rb"  Opens a file for reading only in binary format.
"rb+" Opens a file for both reading and writing in binary format.
"w"   Opens a file for writing only.
"a"   Open for writing.  The file is created if it does not exist.
"a+"  Open for reading and writing.  The file is created if it does not exist.

What's the difference between a POST and a PUT HTTP REQUEST?

Only semantics.

An HTTP PUT is supposed to accept the body of the request, and then store that at the resource identified by the URI.

An HTTP POST is more general. It is supposed to initiate an action on the server. That action could be to store the request body at the resource identified by the URI, or it could be a different URI, or it could be a different action.

PUT is like a file upload. A put to a URI affects exactly that URI. A POST to a URI could have any effect at all.

ASP.NET Temporary files cleanup

Just an update on more current OS's (Vista, Win7, etc.) - the temp file path has changed may be different based on several variables. The items below are not definitive, however, they are a few I have encountered:

"temp" environment variable setting - then it would be:

%temp%\Temporary ASP.NET Files

Permissions and what application/process (VS, IIS, IIS Express) is running the .Net compiler. Accessing the C:\WINDOWS\Microsoft.NET\Framework folders requires elevated permissions and if you are not developing under an account with sufficient permissions then this folder might be used:

c:\Users\[youruserid]\AppData\Local\Temp\Temporary ASP.NET Files

There are also cases where the temp folder can be set via config for a machine or site specific using this:

<compilation tempDirectory="d:\MyTempPlace" />

I even have a funky setup at work where we don't run Admin by default, plus the IT guys have login scripts that set %temp% and I get temp files in 3 different locations depending on what is compiling things! And I'm still not certain about how these paths get picked....sigh.

Still, dthrasher is correct, you can just delete these and VS and IIS will just recompile them as needed.

How to encode a string in JavaScript for displaying in HTML?

If you want to use a library rather than doing it yourself:

The most commonly used way is using jQuery for this purpose:

var safestring = $('<div>').text(unsafestring).html();

If you want to to encode all the HTML entities you will have to use a library or write it yourself.

You can use a more compact library than jQuery, like HTML Encoder and Decode

How to convert a String to CharSequence?

Since String IS-A CharSequence, you can pass a String wherever you need a CharSequence, or assign a String to a CharSequence:

CharSequence cs = "string";
String s = cs.toString();
foo(s); // prints "string"

public void foo(CharSequence cs) { 

If you want to convert a CharSequence to a String, just use the toString method that must be implemented by every concrete implementation of CharSequence.

Hope it helps.

How to filter files when using scp to copy dir recursively?

To exclude dotfiles in base directory:

scp -r [!.]* server:/path/to/something

[!.]* is a shell glob that expands to all files in working directory not starting with a dot.

jQuery: load txt file and insert into div

 <script type="text/javascript">     
   $("#textFileID").html("Loading...").load("URL TEXT");

 <div id="textFileID"></div>

Gridview with two columns and auto resized images

another simple approach with modern built-in stuff like PercentRelativeLayout is now available for new users who hit this problem. thanks to android team for release this item.

< xmlns:android=""

<FrameLayout xmlns:android=""

        android:scaleType="centerCrop" />

        android:textColor="@android:color/white" />


and for better performance you can use some stuff like picasso image loader which help you to fill whole width of every image parents. for example in your adapter you should use this:

int width= context.getResources().getDisplayMetrics().widthPixels;
            .load("some url")

now you dont need CustomImageView Class anymore.

P.S i recommend to use ImageView in place of Type Int in class Item.

hope this help..

Why does HTML think “chucknorris” is a color?


  • The browser will try to convert chucknorris into a hexadecimal value.
  • Since c is the only valid hex character in chucknorris, the value turns into: c00c00000000(0 for all values that were invalid).
  • The browser then divides the result into 3 groupds: Red = c00c, Green = 0000, Blue = 0000.
  • Since valid hex values for html backgrounds only contain 2 digits for each color type (r, g, b), the last 2 digits are truncated from each group, leaving an rgb value of c00000 which is a brick-reddish toned color.

Reading a json file in Android

Put that file in assets.

For project created in Android Studio project you need to create assets folder under the main folder.

Read that file as:

public String loadJSONFromAsset(Context context) {
        String json = null;
        try {
            InputStream is = context.getAssets().open("file_name.json");

            int size = is.available();

            byte[] buffer = new byte[size];



            json = new String(buffer, "UTF-8");

        } catch (IOException ex) {
            return null;
        return json;


and then you can simply read this string return by this function as

JSONObject obj = new JSONObject(json_return_by_the_function);

For further details regarding JSON see

Hope you will get what you want.

Set Radiobuttonlist Selected from Codebehind

You could do:

radio1.SelectedIndex = 1;

But this is the most simple form and would most likely become problematic as your UI grows. Say, for instance, if a team member inserts an item in the RadioButtonList above option2 but doesn't know we use magic numbers in code-behind to select - now the app selects the wrong index!

Maybe you want to look into using FindControl in order to determine the ListItem actually required, by name, and selecting appropriately. For instance:

//omitting possible null reference checks...
var wantedOption = radio1.FindControl("option2").Selected = true;

Get selected value in dropdown list using JavaScript

var strUser = e.options[e.selectedIndex].value;

This is correct and should give you the value. Is it the text you're after?

var strUser = e.options[e.selectedIndex].text;

So you're clear on the terminology:

    <option value="hello">Hello World</option>

This option has:

  • Index = 0
  • Value = hello
  • Text = Hello World

PL/SQL ORA-01422: exact fetch returns more than requested number of rows

It can also be due to a duplicate entry in any of the tables that are used.

How to send a simple email from a Windows batch file?

$emailSmtpServerPort = "587"
$emailSmtpUser = "username"
$emailSmtpPass = 'password'
$emailMessage = New-Object System.Net.Mail.MailMessage
$emailMessage.From = "[From email address]"
$emailMessage.To.Add( "[Send to email address]" )
$emailMessage.Subject = "Testing e-mail"
$emailMessage.IsBodyHtml = $true
$emailMessage.Body = @"
<p>Here is a message that is <strong>HTML formatted</strong>.</p>
<p>From your friendly neighborhood IT guy</p>
$SMTPClient = New-Object System.Net.Mail.SmtpClient( $emailSmtpServer , $emailSmtpServerPort )
$SMTPClient.EnableSsl = $true
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential( $emailSmtpUser , $emailSmtpPass );
$SMTPClient.Send( $emailMessage )

Convert DataTable to List<T>

That pretty works!!

I made some updates from @suneelsarraf's answer and I removed Convert.ChangeType() because it keeps throwing Invalid Cast Exception. Have a take a look!

#region *** Convert DT to List<Object> ***

    private List<I> ConvertTo<I>(DataTable datatable) where I : class
        List<I> lstRecord = new List<I>();
            List<string> columnsNames = new List<string>();
            foreach (DataColumn DataColumn in datatable.Columns)
            lstRecord = datatable.AsEnumerable().ToList().ConvertAll<I>(row => GetObject<I>(row, columnsNames));
            return lstRecord;
            return lstRecord;


    private I GetObject<I>(DataRow row, List<string> columnsName) where I : class
        I obj = (I)Activator.CreateInstance(typeof(I));
            PropertyInfo[] Properties = typeof(I).GetProperties();
            foreach (PropertyInfo objProperty in Properties)
                string columnname = columnsName.Find(name => name.ToLower() == objProperty.Name.ToLower());
                if (!string.IsNullOrEmpty(columnname))
                    object dbValue = row[columnname];
                    if (dbValue != DBNull.Value)
                        if (Nullable.GetUnderlyingType(objProperty.PropertyType) != null)
                            objProperty.SetValue(obj, Convert.ChangeType(dbValue, Type.GetType(Nullable.GetUnderlyingType(objProperty.PropertyType).ToString())), null);
                            objProperty.SetValue(obj, Convert.ChangeType(dbValue, Type.GetType(objProperty.PropertyType.ToString())), null);
            return obj;
        catch(Exception ex)
            return obj;


And this is how you use in your code.

// Other Codes Here
var lstResult = ConvertTo<TEntity>(dataTableName); // Convert DT to List<TEntity>

Have Fun! Be Safe in 2020.

How to select only the records with the highest date in LINQ

It could be something like:

var qry = from t in db.Lasttraces
          group t by t.AccountId into g
          orderby t.Date
          select new { g.AccountId, Date = g.Max(e => e.Date) };

How to write to a file, using the logging Python module?

Taken from the "logging cookbook":

# create logger with 'spam_application'
logger = logging.getLogger('spam_application')
# create file handler which logs even debug messages
fh = logging.FileHandler('spam.log')

And you're good to go.

P.S. Make sure to read the logging HOWTO as well.

Drag and drop a DLL to the GAC ("assembly") in windows server 2008 .net 4.0

In .net 4.0 Microsoft removed the ability to add DLLs to the Assembly simply by dragging and dropping.

Instead you need to use gacutil.exe, or create an installer to do it. Microsoft actually doesn’t recommend using gacutil, but I went that route anyway.

To use gacutil on a development machine go to:
Start -> programs -> Microsoft Visual studio 2010 -> Visual Studio Tools -> Visual Studio Command Prompt (2010)

Then use these commands to uninstall and Reinstall respectively. Note I did NOT include .dll in the uninstall command.
gacutil /u myDLL
gacutil /i "C:\Program Files\Custom\myDLL.dll"

To use Gacutil on a non-development machine you will have to copy the executable and config file from your dev machine to the production machine. It looks like there are a few different versions of Gacutil. The one that worked for me, I found here:
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools\gacutil.exe C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools\gacutil.exe.config

Copy the files here or to the appropriate .net folder;

Then use these commands to uninstall and reinstall respectively
"C:\Users\BHJeremy\Desktop\Installing to the Gac in .net 4.0\gacutil.exe" /u "myDLL"

"C:\Windows\Microsoft.NET\Framework\v4.0.30319\gacutil.exe" /i "C:\Program Files\Custom\myDLL.dll"

PHP AES encrypt / decrypt

If you don't want to use a heavy dependency for something solvable in 15 lines of code, use the built in OpenSSL functions. Most PHP installations come with OpenSSL, which provides fast, compatible and secure AES encryption in PHP. Well, it's secure as long as you're following the best practices.

The following code:

  • uses AES256 in CBC mode
  • is compatible with other AES implementations, but not mcrypt, since mcrypt uses PKCS#5 instead of PKCS#7.
  • generates a key from the provided password using SHA256
  • generates a hmac hash of the encrypted data for integrity check
  • generates a random IV for each message
  • prepends the IV (16 bytes) and the hash (32 bytes) to the ciphertext
  • should be pretty secure

IV is a public information and needs to be random for each message. The hash ensures that the data hasn't been tampered with.

function encrypt($plaintext, $password) {
    $method = "AES-256-CBC";
    $key = hash('sha256', $password, true);
    $iv = openssl_random_pseudo_bytes(16);

    $ciphertext = openssl_encrypt($plaintext, $method, $key, OPENSSL_RAW_DATA, $iv);
    $hash = hash_hmac('sha256', $ciphertext . $iv, $key, true);

    return $iv . $hash . $ciphertext;

function decrypt($ivHashCiphertext, $password) {
    $method = "AES-256-CBC";
    $iv = substr($ivHashCiphertext, 0, 16);
    $hash = substr($ivHashCiphertext, 16, 32);
    $ciphertext = substr($ivHashCiphertext, 48);
    $key = hash('sha256', $password, true);

    if (!hash_equals(hash_hmac('sha256', $ciphertext . $iv, $key, true), $hash)) return null;

    return openssl_decrypt($ciphertext, $method, $key, OPENSSL_RAW_DATA, $iv);


$encrypted = encrypt('Plaintext string.', 'password'); // this yields a binary string

echo decrypt($encrypted, 'password');
// decrypt($encrypted, 'wrong password') === null

edit: Updated to use hash_equals and added IV to the hash.

Can typescript export a function?

In my case I'm doing it like this:

 module SayHi {
    export default () => { console.log("Hi"); }
 new SayHi();

How do I enable EF migrations for multiple contexts to separate databases?

EF 4.7 actually gives a hint when you run Enable-migrations at multiple context.

More than one context type was found in the assembly 'Service.Domain'.

To enable migrations for 'Service.Domain.DatabaseContext.Context1', 
use Enable-Migrations -ContextTypeName Service.Domain.DatabaseContext.Context1.
To enable migrations for 'Service.Domain.DatabaseContext.Context2',
use Enable-Migrations -ContextTypeName Service.Domain.DatabaseContext.Context2.

jQuery date/time picker

I have ran into that same problem. I actually developed my using server side programming, but I did a quick search to try and help you out and found this.

Seems alright, didn't look at the source too much, but seems to be purely JavaScript.

Take look:

Here is the demo page link:

good luck

Get Android shared preferences value in activity/normal class

You use uninstall the app and change the sharedPreferences name then run this application. I think it will resolve the issue.

A sample code to retrieve values from sharedPreferences you can use the following set of code,

SharedPreferences shared = getSharedPreferences(PREF_NAME, MODE_PRIVATE);
String channel = (shared.getString(keyValue, ""));

What is the SSIS package and what does it do?

Microsoft SQL Server Integration Services (SSIS) is a platform for building high-performance data integration solutions, including extraction, transformation, and load (ETL) packages for data warehousing. SSIS includes graphical tools and wizards for building and debugging packages; tasks for performing workflow functions such as FTP operations, executing SQL statements, and sending e-mail messages; data sources and destinations for extracting and loading data; transformations for cleaning, aggregating, merging, and copying data; a management database, SSISDB, for administering package execution and storage; and application programming interfaces (APIs) for programming the Integration Services object model.

As per Microsoft, the main uses of SSIS Package are:

• Merging Data from Heterogeneous Data Stores Populating Data

• Warehouses and Data Marts Cleaning and Standardizing Data Building

• Business Intelligence into a Data Transformation Process Automating

• Administrative Functions and Data Loading

For developers:

SSIS Package can be integrated with VS development environment for building Business Intelligence solutions. Business Intelligence Development Studio is the Visual Studio environment with enhancements that are specific to business intelligence solutions. It work with 32-bit development environment only.

Download SSDT tools for Visual Studio:

Creating SSIS ETL Package - Basics :

Sample project of SSIS features in 6 lessons:

How do I encrypt and decrypt a string in python?

Take a look at PyCrypto. It supports Python 3.2 and does exactly what you want.

From their pip website:

>>> from Crypto.Cipher import AES
>>> obj ='This is a key123', AES.MODE_CFB, 'This is an IV456')
>>> message = "The answer is no"
>>> ciphertext = obj.encrypt(message)
>>> ciphertext
>>> obj2 ='This is a key123', AES.MODE_CFB, 'This is an IV456')
>>> obj2.decrypt(ciphertext)
'The answer is no'

If you want to encrypt a message of an arbitrary size use AES.MODE_CFB instead of AES.MODE_CBC.

ERROR 1396 (HY000): Operation CREATE USER failed for 'jack'@'localhost'

Funnily enough the MySQL workbench solved it for me. In the Administration tab -> Users and Privileges, the user was listed with an error. Using the delete option solved the problem.

Send FormData with other field in AngularJS

You're sending JSON-formatted data to a server which isn't expecting that format. You already provided the format that the server needs, so you'll need to format it yourself which is pretty simple.

var data = '"title='+title+'" "text='+text+'" "file='+file+'"';
$, data)

How to specify different Debug/Release output directories in QMake .pro file

The new version of Qt Creator also has a "profile" build option between debug and release. Here's how I'm detecting that:

CONFIG(debug, debug|release) {  DEFINES += DEBUG_MODE }
else:CONFIG(force_debug_info) { DEFINES += PROFILE_MODE }
else {                          DEFINES += RELEASE_MODE }

How can I send the "&" (ampersand) character via AJAX?

You might want to use encodeURIComponent().

encodeURIComponent("&quot;Busola&quot;"); // => %26quot%3BBusola%26quot%3B

Illegal access: this web application instance has been stopped already

I suspect that this occurs after an attempt to undeploy your app. Do you ever kill off that thread that you've initialised during the init() process ? I would do this in the corresponding destroy() method.

String, StringBuffer, and StringBuilder

Also, StringBuffer is thread-safe, which StringBuilder is not.

So in a real-time situation when different threads are accessing it, StringBuilder could have an undeterministic result.

Specifying content of an iframe instead of the src attribute to a page

You can .write() the content into the iframe document. Example:

<iframe id="FileFrame" src="about:blank"></iframe>

<script type="text/javascript">
   var doc = document.getElementById('FileFrame').contentWindow.document;;
   doc.write('<html><head><title></title></head><body>Hello world.</body></html>');

Run JavaScript in Visual Studio Code

The shortcut for the integrated terminal is ctrl + `, then type node <filename>.

Alternatively you can create a task. This is the only code in my tasks.json:

// See
// for the documentation about the tasks.json format
"version": "0.1.0",
"command": "node",
"isShellCommand": true,
"args": ["${file}"],
"showOutput": "always"

From here create a shortcut. This is my keybindings.json:

// Place your key bindings in this file to overwrite the defaults
{   "key": "cmd+r",
"command": "workbench.action.tasks.runTask"
{   "key": "cmd+e",
"command": "workbench.action.output.toggleOutput"

This will open 'run' in the Command Pallete, but you still have to type or select with the mouse the task you want to run, in this case node. The second shortcut toggles the output panel, there's already a shortcut for it but these keys are next to each other and easier to work with.

Django - taking values from POST request

Read about request objects that your views receive:

Also your hidden field needs a reliable name and then a value:

<input type="hidden" name="title" value="{{ source.title }}">

Then in a view:

request.POST.get("title", "")

Can I make a <button> not submit a form?

The button element has a default type of submit.

You can make it do nothing by setting a type of button:

<button type="button">Cancel changes</button>

How to change default timezone for Active Record in Rails?

On rails 4.2.2, go to application.rb and use config.time_zone='city' (e.g.:'London' or 'Bucharest' or 'Amsterdam' and so on).

It should work just fine. It worked for me.

Can I use a case/switch statement with two variables?

First, JavaScript's switch is no faster than if/else (and sometimes much slower).

Second, the only way to use switch with multiple variables is to combine them into one primitive (string, number, etc) value:

var stateA = "foo";
var stateB = "bar";
switch (stateA + "-" + stateB) {
    case "foo-bar": ...

But, personally, I would rather see a set of if/else statements.

Edit: When all the values are integers, it appears that switch can out-perform if/else in Chrome. See the comments.

How can I convert a Word document to PDF?

This is quite a hard task, ever harder if you want perfect results (impossible without using Word) as such the number of APIs that just do it all for you in pure Java and are open source is zero I believe (Update: I am wrong, see below).

Your basic options are as follows:

  1. Using JNI/a C# web service/etc script MS Office (only option for 100% perfect results)
  2. Using the available APIs script Open Office (90+% perfect)
  3. Use Apache POI & iText (very large job, will never be perfect).

Update - 2016-02-11 Here is a cut down copy of my blog post on this subject which outlines existing products that support Word-to-PDF in Java.

Converting Microsoft Office (Word, Excel) documents to PDFs in Java

Three products that I know of can render Office documents:

yeokm1/docs-to-pdf-converter Irregularly maintained, Pure Java, Open Source Ties together a number of libraries to perform the conversion.

xdocreport Actively developed, Pure Java, Open Source It's Java API to merge XML document created with MS Office (docx) or OpenOffice (odt), LibreOffice (odt) with a Java model to generate report and convert it if you need to another format (PDF, XHTML...).

Snowbound Imaging SDK Closed Source, Pure Java Snowbound appears to be a 100% Java solution and costs over $2,500. It contains samples describing how to convert documents in the evaluation download.

OpenOffice API Open Source, Not Pure Java - Requires Open Office installed OpenOffice is a native Office suite which supports a Java API. This supports reading Office documents and writing PDF documents. The SDK contains an example in document conversion (examples/java/DocumentHandling/ To write PDFs you need to pass the "writer_pdf_Export" writer rather than the "MS Word 97" one. Or you can use the wrapper API JODConverter.

JDocToPdf - Dead as of 2016-02-11 Uses Apache POI to read the Word document and iText to write the PDF. Completely free, 100% Java but has some limitations.

Git Ignores and Maven targets

I ignore all classes residing in target folder from git. add following line in open .gitignore file:




It is working perfectly for me. try it.

Issue when importing dataset: `Error in scan(...): line 1 did not have 145 elements`

For others who can't find a solution and know the data isn't missing elements:

I have this issue when I use Excel 2013 to save files as .csv and then try to load them in R using read.table(). The workaround I have found is to paste the data straight from Excel into a .txt document, then open with:

read.table(file.choose(), sep="\t").

I hope this helps.

Understanding esModuleInterop in tsconfig file

Problem statement

Problem occurs when we want to import CommonJS module into ES6 module codebase.

Before these flags we had to import CommonJS modules with star (* as something) import:

// node_modules/moment/index.js
exports = moment
// index.ts file in our app
import * as moment from 'moment'
moment(); // not compliant with es6 module spec

// transpiled js (simplified):
const moment = require("moment");

We can see that * was somehow equivalent to exports variable. It worked fine, but it wasn't compliant with es6 modules spec. In spec, the namespace record in star import (moment in our case) can be only a plain object, not callable (moment() is not allowed).


With flag esModuleInterop we can import CommonJS modules in compliance with es6 modules spec. Now our import code looks like this:

// index.ts file in our app
import moment from 'moment'
moment(); // compliant with es6 module spec

// transpiled js with esModuleInterop (simplified):
const moment = __importDefault(require('moment'));

It works and it's perfectly valid with es6 modules spec, because moment is not namespace from star import, it's default import.

But how does it work? As you can see, because we did a default import, we called the default property on a moment object. But we didn't declare a default property on the exports object in the moment library. The key is the __importDefault function. It assigns module (exports) to the default property for CommonJS modules:

var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };

As you can see, we import es6 modules as they are, but CommonJS modules are wrapped into an object with the default key. This makes it possible to import defaults on CommonJS modules.

__importStar does the similar job - it returns untouched esModules, but translates CommonJS modules into modules with a default property:

// index.ts file in our app
import * as moment from 'moment'

// transpiled js with esModuleInterop (simplified):
const moment = __importStar(require("moment"));
// note that "moment" is now uncallable - ts will report error!
var __importStar = (this && this.__importStar) || function (mod) {
    if (mod && mod.__esModule) return mod;
    var result = {};
    if (mod != null) for (var k in mod) if (, k)) result[k] = mod[k];
    result["default"] = mod;
    return result;

Synthetic imports

And what about allowSyntheticDefaultImports - what is it for? Now the docs should be clear:

Allow default imports from modules with no default export. This does not affect code emit, just typechecking.

In moment typings we don't have specified default export, and we shouldn't have, because it's available only with flag esModuleInterop on. So allowSyntheticDefaultImports will not report an error if we want to import default from a third-party module which doesn't have a default export.

Replace a character at a specific index in a string?

As previously answered here, String instances are immutable. StringBuffer and StringBuilder are mutable and suitable for such a purpose whether you need to be thread safe or not.

There is however a way to modify a String but I would never recommend it because it is unsafe, unreliable and it can can be considered as cheating : you can use reflection to modify the inner char array the String object contains. Reflection allows you to access fields and methods that are normally hidden in the current scope (private methods or fields from another class...).

public static void main(String[] args) {
    String text = "This is a test";
    try {
        //String.value is the array of char (char[])
        //that contains the text of the String
        Field valueField = String.class.getDeclaredField("value");
        //String.value is a private variable so it must be set as accessible 
        //to read and/or to modify its value
        //now we get the array the String instance is actually using
        char[] value = (char[])valueField.get(text);
        //The 13rd character is the "s" of the word "Test"
        //We display the string which should be "This is a text"
    } catch (NoSuchFieldException | SecurityException e) {
    } catch (IllegalArgumentException e) {
    } catch (IllegalAccessException e) {

How do you format an unsigned long long int using printf?

In Linux it is %llu and in Windows it is %I64u

Although I have found it doesn't work in Windows 2000, there seems to be a bug there!

Pass PDO prepared statement to variables

You could do $stmt->queryString to obtain the SQL query used in the statement. If you want to save the entire $stmt variable (I can't see why), you could just copy it. It is an instance of PDOStatement so there is apparently no advantage in storing it.

Java integer list

code that works, but output is:



    List<Integer> myCoords = new ArrayList<Integer>();
    for (Integer number : myCoords) {
        try {
        } catch (InterruptedException e) {

Checking images for similarity with OpenCV

Sam's solution should be sufficient. I've used combination of both histogram difference and template matching because not one method was working for me 100% of the times. I've given less importance to histogram method though. Here's how I've implemented in simple python script.

import cv2

class CompareImage(object):

    def __init__(self, image_1_path, image_2_path):
        self.minimum_commutative_image_diff = 1
        self.image_1_path = image_1_path
        self.image_2_path = image_2_path

    def compare_image(self):
        image_1 = cv2.imread(self.image_1_path, 0)
        image_2 = cv2.imread(self.image_2_path, 0)
        commutative_image_diff = self.get_image_difference(image_1, image_2)

        if commutative_image_diff < self.minimum_commutative_image_diff:
            print "Matched"
            return commutative_image_diff
        return 10000 //random failure value

    def get_image_difference(image_1, image_2):
        first_image_hist = cv2.calcHist([image_1], [0], None, [256], [0, 256])
        second_image_hist = cv2.calcHist([image_2], [0], None, [256], [0, 256])

        img_hist_diff = cv2.compareHist(first_image_hist, second_image_hist, cv2.HISTCMP_BHATTACHARYYA)
        img_template_probability_match = cv2.matchTemplate(first_image_hist, second_image_hist, cv2.TM_CCOEFF_NORMED)[0][0]
        img_template_diff = 1 - img_template_probability_match

        # taking only 10% of histogram diff, since it's less accurate than template method
        commutative_image_diff = (img_hist_diff / 10) + img_template_diff
        return commutative_image_diff

    if __name__ == '__main__':
        compare_image = CompareImage('image1/path', 'image2/path')
        image_difference = compare_image.compare_image()
        print image_difference

What's the difference between returning value or Promise.resolve from then()

In simple terms, inside a then handler function:

A) When x is a value (number, string, etc):

  1. return x is equivalent to return Promise.resolve(x)
  2. throw x is equivalent to return Promise.reject(x)

B) When x is a Promise that is already settled (not pending anymore):

  1. return x is equivalent to return Promise.resolve(x), if the Promise was already resolved.
  2. return x is equivalent to return Promise.reject(x), if the Promise was already rejected.

C) When x is a Promise that is pending:

  1. return x will return a pending Promise, and it will be evaluated on the subsequent then.

Read more on this topic on the Promise.prototype.then() docs.

How to set HTML5 required attribute in Javascript?

What matters isn't the attribute but the property, and its value is a boolean.

You can set it using

 document.getElementById("edName").required = true;

Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required

When you try to send mail from code and you find the error "The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required", than the error might occur due to following cases.

case 1: when the password is wrong

case 2: when you try to login from some App

case 3: when you try to login from the domain other than your time zone/domain/computer (This is the case in most of scenarios when sending mail from code)

There is a solution for each

solution for case 1: Enter the correct password.

solution 1 for case 2: go to security settings at the followig link and enable less secure apps . So that you will be able to login from all apps.

solution 2 for case 2:(see enable two-factor authentication (aka two-step verification) , and then generate an application-specific password. Use that newly generated password to authenticate via SMTP.

solution 1 for case 3: (This might be helpful) you need to review the activity. but reviewing the activity will not be helpful due to latest security standards the link will not be useful. So try the below case.

solution 2 for case 3: If you have hosted your code somewhere on production server and if you have access to the production server, than take remote desktop connection to the production server and try to login once from the browser of the production server. This will add excpetioon for login to google and you will be allowed to login from code.

But what if you don't have access to the production server. try the solution 3

solution 3 for case 3: You have to enable login from other timezone / ip for your google account.

to do this follow the link and allow access by clicking the continue button.

And that's it. Here you go. Now you will be able to login from any of the computer and by any means of app to your google account.

How to force a web browser NOT to cache images

I use PHP's file modified time function, for example:

echo <img  src='Images/image.png?" . filemtime('Images/image.png') . "'  />";

If you change the image then the new image is used rather than the cached one, due to having a different modified timestamp.

Maximum execution time in phpMyadmin

ini_set('max_execution_time', 0); or create file name called php.ini and enter the first line max_execution_time=0 then save it and put the file in your root folder of your application.

That's it. Good luck.

IIS7 URL Redirection from root to sub directory

I think, this could be done without IIS URL Rewrite module. <httpRedirect> supports wildcards, so you can configure it this way:

    <httpRedirect enabled="true">
      <add wildcard="/" destination="/menu_1/MainScreen.aspx" />

Note that you need to have the "HTTP Redirection" feature enabled on IIS - see HTTP Redirects

Clone only one branch

From the announcement Git 1.7.10 (April 2012):

  • git clone learned --single-branch option to limit cloning to a single branch (surprise!); tags that do not point into the history of the branch are not fetched.

Git actually allows you to clone only one branch, for example:

git clone -b mybranch --single-branch git://

Note: Also you can add another single branch or "undo" this action.

org.hibernate.MappingException: Could not determine type for: java.util.Set

I got the same problem with @ManyToOne column. It was solved... in stupid way. I had all other annotations for public getter methods, because they were overridden from parent class. But last field was annotated for private variable like in all other classes in my project. So I got the same MappingException without the reason.

Solution: I placed all annotations at public getter methods. I suppose, Hibernate can't handle cases, when annotations for private fields and public getters are mixed in one class.

How to maximize the browser window in Selenium WebDriver (Selenium 2) using C#?

I had the same problem, but the problem can be solved by using following code.


git status shows modifications, git checkout -- <file> doesn't remove them

Another solution that may work for people, since none of the text options worked for me:

  1. Replace the content of .gitattributes with a single line: * binary. This tells git to treat every file as a binary file that it can't do anything with.
  2. Check that message for the offending files is gone; if it's not you can git checkout -- <files> to restore them to the repository version
  3. git checkout -- .gitattributes to restore the .gitattributes file to its initial state
  4. Check that the files are still not marked as changed.

how to customise input field width in bootstrap 3

In Bootstrap 3, .form-control (the class you give your inputs) has a width of 100%, which allows you to wrap them into col-lg-X divs for arrangement. Example from the docs:

<div class="row">
  <div class="col-lg-2">
    <input type="text" class="form-control" placeholder=".col-lg-2">
  <div class="col-lg-3">
    <input type="text" class="form-control" placeholder=".col-lg-3">
  <div class="col-lg-4">
    <input type="text" class="form-control" placeholder=".col-lg-4">

See under Column sizing.

It's a bit different than in Bootstrap 2.3.2, but you get used to it quickly.

Non greedy (reluctant) regex matching in sed?

sed certainly has its place but this not not one of them !

As Dee has pointed out: Just use cut. It is far simpler and much more safe in this case. Here's an example where we extract various components from the URL using Bash syntax:


protocol=$(echo "$url" | cut -d':' -f1)
host=$(echo "$url" | cut -d'/' -f3)
urlhost=$(echo "$url" | cut -d'/' -f1-3)
urlpath=$(echo "$url" | cut -d'/' -f4-)

gives you:

protocol = "http"
host = ""
urlhost = ""
urlpath = "product/174/71/3816/"

As you can see this is a lot more flexible approach.

(all credit to Dee)

"The stylesheet was not loaded because its MIME type, "text/html" is not "text/css"

This is more likely an issue at your server side. you request style sheet page "Styles/Site.css" from the server of type "text/css", but your server might be responding to this request with "test/html". I had this issue when my server was running in python and it was replying to requested css files with header text/html (as that of my index.html file). I re-arranged my server code and assigned the correct headers to its corresponding pages and my issue got resolved.

How do a send an HTTPS request through a proxy in Java?

Try the Apache Commons HttpClient library instead of trying to roll your own:

From their sample code:

  HttpClient httpclient = new HttpClient();
  httpclient.getHostConfiguration().setProxy("myproxyhost", 8080);

  /* Optional if authentication is required.
  httpclient.getState().setProxyCredentials("my-proxy-realm", " myproxyhost",
   new UsernamePasswordCredentials("my-proxy-username", "my-proxy-password"));

  PostMethod post = new PostMethod("https://someurl");
  NameValuePair[] data = {
     new NameValuePair("user", "joe"),
     new NameValuePair("password", "bloggs")
  // execute method and handle any error responses.
  // ...
  InputStream in = post.getResponseBodyAsStream();
  // handle response.

  /* Example for a GET reqeust
  GetMethod httpget = new GetMethod("https://someurl");
  try { 
  } finally {

Getting the parent of a directory in Bash

Clearly the parent directory is given by simply appending the dot-dot filename:

/home/smith/Desktop/Test/..     # unresolved path

But you must want the resolved path (an absolute path without any dot-dot path components):

/home/smith/Desktop             # resolved path

The problem with the top answers that use dirname, is that they don't work when you enter a path with dot-dots:

$ dir=~/Library/../Desktop/../..
$ parentdir="$(dirname "$dir")"
$ echo $parentdir
/Users/username/Library/../Desktop/..   # not fully resolved

This is more powerful:

parentdir=$(builtin cd $dir; pwd)

You can feed it /home/smith/Desktop/Test/.., but also more complex paths like:

$ dir=~/Library/../Desktop/../..
$ parentdir=$(builtin cd $dir; pwd)
$ echo $parentdir
/Users                                  # the fully resolved path!

NOTE: use of builtin ensures no user defined function variant of cd is called, but rather the default utility form which has no output.

How to find unused/dead code in java projects

I use Doxygen to develop a method call map to locate methods that are never called. On the graph you will find islands of method clusters without callers. This doesn't work for libraries since you need always start from some main entry point.

How to set opacity in parent div and not affect in child div?

May be it's good if you define your background-image in the :after pseudo class. Write like this:

    border:1px solid red;

Check this fiddle

CSS: How to change colour of active navigation page menu

I think you are getting confused about what the a:active CSS selector does. This will only change the colour of your link when you click it (and only for the duration of the click i.e. how long your mouse button stays down). What you need to do is introduce a new class e.g. .selected into your CSS and when you select a link, update the selected menu item with new class e.g.

<div class="menuBar">
        <li class="selected"><a href="index.php">HOME</a></li>
        <li><a href="two.php">PORTFOLIO</a></li>

// specific CSS for your menu
div.menuBar li.selected a { color: #FF0000; } 
// more general CSS
li.selected a { color: #FF0000; }

You will need to update your template page to take in a selectedPage parameter.

Find the nth occurrence of substring in a string

Providing another "tricky" solution, which use split and join.

In your example, we can use

len("substring".join([s for s in ori.split("substring")[:2]]))

jQuery Scroll to bottom of page/iframe

A simple function that jumps (instantly scrolls) to the bottom of the whole page. It uses the built-in .scrollTop(). I haven’t tried to adapt this to work with individual page elements.

function jumpToPageBottom() {
    $('html, body').scrollTop( $(document).height() - $(window).height() );

How to find whether a number belongs to a particular range in Python?

Old faithful:

if n >= a and n <= b:

And it doesn't look like Perl (joke)