Trending questions in Java

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Recursively delete directories in Java

You can try using the FileUtils class of Apache's commons-io: FileUtils.deleteDirectory(new ...READ MORE

Oct 23, 2018 in Java by code.reaper12
 • 3,500 points • 368 views
0 votes
1 answer

What is the meaning of 'Synchronized'?

The synchronized keyword is about different threads reading and ...READ MORE

Oct 17, 2018 in Java by Parth
 • 4,630 points • 568 views
+1 vote
1 answer

How to calculate days between two dates?

You are making some conversions with your ...READ MORE

Aug 28, 2018 in Java by Frankie
 • 9,830 points • 2,661 views
0 votes
1 answer

Java equals() vs Arrays.equals()

Here, array1.equals(array2)meansarray1 == array2 That is, it checks whether ...READ MORE

Oct 11, 2018 in Java by code.reaper12
 • 3,500 points • 764 views
0 votes
2 answers

How is hashmap different from hashtable?

HashMap and HashTable: 1) Hashtable and Hashmap implement ...READ MORE

Aug 1, 2018 in Java by samarth295
 • 2,220 points • 6,089 views
+2 votes
1 answer

What is the meaning of "this" keyword in Java?

public class MyThisTest { private int ...READ MORE

Oct 10, 2018 in Java by Daisy
 • 8,120 points • 697 views
0 votes
1 answer

System.exit() method in Java

System.exit() is a method of System class ...READ MORE

Sep 28, 2018 in Java by code.reaper12
 • 3,500 points • 1,324 views
0 votes
2 answers

C++ performance vs. Java/C#

The overhead of interpreting code is much higher than ...READ MORE

Dec 27, 2018 in Java by iangregor
 • 300 points • 1,119 views
0 votes
1 answer

Importing properties file from Java package

In case your class is present within ...READ MORE

Oct 15, 2018 in Java by code.reaper12
 • 3,500 points • 419 views
0 votes
1 answer

Tail call optimization in JVM

The tail call optimization in JVM is difficult ...READ MORE

Oct 10, 2018 in Java by geek.erkami
 • 2,680 points • 674 views
0 votes
1 answer

How to use ThreadLocal variable

You can use a ThreadLocal variable when you have some ...READ MORE

Oct 11, 2018 in Java by code.reaper12
 • 3,500 points • 621 views
0 votes
1 answer

How can we add local .jar file dependency to build.gradle file?

You can refer the below code if ...READ MORE

Jun 27, 2018 in Java by Akrati
 • 960 points • 5,114 views
0 votes
1 answer

Randomly selecting an element from an array

For randomly selecting an element, java.util.Random provides ...READ MORE

Oct 11, 2018 in Java by anto.trigg4
 • 3,440 points • 510 views
0 votes
1 answer

Non-static method within Static method in Java

As per my knowledge, you are getting this error ...READ MORE

Sep 28, 2018 in Java by anto.trigg4
 • 3,440 points • 1,083 views
0 votes
1 answer

How to display an animated GIF?

Android actually can decode and display animated ...READ MORE

Oct 8, 2018 in Java by sharth
 • 3,370 points • 622 views
0 votes
1 answer

Java's default package

Yes, technically, using the package names should ...READ MORE

Oct 9, 2018 in Java by code.reaper12
 • 3,500 points • 584 views
0 votes
1 answer

How do you produce a double in Java

double num = 5; When you do this, ...READ MORE

Oct 4, 2018 in Java by anto.trigg4
 • 3,440 points • 640 views
0 votes
2 answers

How can I Copy files from one directory to another in Java

Java 8 Path sourcepath = Paths.get("C:\\data\\temp\\mydir"); ...READ MORE

Aug 10, 2018 in Java by samarth295
 • 2,220 points • 4,200 views
0 votes
1 answer

@Qualifier annotation in Spring Framework

When you create more than one bean ...READ MORE

Sep 10, 2018 in Java by code.reaper12
 • 3,500 points • 1,611 views
0 votes
1 answer

System.currentTimeMillis vs System.nanoTime

In case you want extremely precise measurements ...READ MORE

Aug 10, 2018 in Java by code.reaper12
 • 3,500 points • 2,943 views
0 votes
1 answer

Fixing android.os.NetworkOnMainThreadException in Java

Android has some good tips on good ...READ MORE

Jun 12, 2018 in Java by Rishabh
 • 3,620 points • 5,401 views
+1 vote
1 answer

Performance difference of if/else vs switch statement in Java

The thing you are worried about is ...READ MORE

Jul 26, 2018 in Java by geek.erkami
 • 2,680 points • 3,456 views
0 votes
2 answers

How can we assert, that a certain Exception is thrown in JUnit 4 tests?

@Test(expected = IndexOutOfBoundsException.class) public void testIndexOutOfBoundsException() { ...READ MORE

Dec 10, 2018 in Java by Sushmita
 • 6,910 points • 1,264 views
+1 vote
1 answer

What if several ports required by tomacat server at local host are already in use

You've another instance of Tomcat already running. ...READ MORE

May 31, 2018 in Java by Akrati
 • 3,190 points • 5,812 views
0 votes
1 answer

How can we get the current location in Android?

First you need to define a LocationListener to handle ...READ MORE

Sep 25, 2018 in Java by Parth
 • 4,630 points • 780 views
0 votes
1 answer

How to pass an object from one activity to another on Android

One option could be letting your custom ...READ MORE

Jun 25, 2018 in Java by Rishabh
 • 3,620 points • 4,702 views
0 votes
2 answers

“Could not find or load main class” mean?

Use the final modifier to enforce good initialization. Avoid returning ...READ MORE

Sep 18, 2018 in Java by Sushmita
 • 6,910 points • 4,255 views
0 votes
2 answers

How to left pad a string with zero in java?

String paddedString = org.apache.commons.lang.StringUtils.leftPad("129018", 10, "0") the second ...READ MORE

Aug 31, 2018 in Java by Sushmita
 • 6,910 points • 2,925 views
0 votes
1 answer

Java anonymous code blocks

The anonymous code blocks in Java are ...READ MORE

Sep 5, 2018 in Java by anto.trigg4
 • 3,440 points • 1,475 views
0 votes
1 answer

What is the best Java email address validation method?

Apache Commons is generally known as a ...READ MORE

Sep 26, 2018 in Java by Parth
 • 4,630 points • 575 views
0 votes
1 answer

How to prevent java.lang.NumberFormatException in Java?

"N/A" is not integer. It must throw NumberFormatException if you ...READ MORE

Jun 26, 2018 in Java by sharth
 • 3,370 points • 4,518 views
0 votes
2 answers

Determining Class of an Object in Java

You can use: Object instance = new SomeClass(); instance.getClass().getName(); ...READ MORE

Nov 26, 2018 in Java by Sushmita
 • 6,910 points • 1,733 views
0 votes
1 answer

Various Advice in Spring AOP

Below are the various advices available in AOP: Before: These types ...READ MORE

Sep 12, 2018 in Java by geek.erkami
 • 2,680 points • 1,151 views
0 votes
1 answer

Spring AOP vs AspectJ AOP

Well, below I have listed down few ...READ MORE

Sep 10, 2018 in Java by v.liyyah
 • 1,300 points • 1,211 views
0 votes
1 answer

Use Servlets with Ajax

Here, we are going to create the ...READ MORE

Jul 16, 2018 in Java by Akrati
 • 3,190 points • 3,632 views
0 votes
1 answer

How to call a method after a delay in Android using Java?

final Handler handler = new Handler(); handler.postDelayed(new Runnable() ...READ MORE

Jun 11, 2018 in Java by Akrati
 • 3,190 points • 5,127 views
0 votes
1 answer

Good Hash Function for Strings

Usually hashes wouldn't do sums, otherwise, stop and pots will have ...READ MORE

Jul 19, 2018 in Java by Akrati
 • 960 points • 3,477 views
0 votes
1 answer

Simple HTTP server in Java using only Java SE API

You can write a pretty simple embedded Jetty Java ...READ MORE

Aug 29, 2018 in Java by Parth
 • 4,630 points • 1,706 views
0 votes
1 answer

Join array elements with a separator in Java

Using Java 8, you can easily perform ...READ MORE

Aug 16, 2018 in Java by geek.erkami
 • 2,680 points • 2,219 views
0 votes
1 answer

Increasing the JVM memory using command line

You can adjust your JVM memory needs by ...READ MORE

Sep 25, 2018 in Java by geek.erkami
 • 2,680 points • 495 views
+12 votes
3 answers

How do I set or change the PATH system variable?

First make sure you have installed JDK ...READ MORE

Aug 28, 2018 in Java by slayer
 • 29,350 points • 1,072 views
0 votes
1 answer

What is the simplest way to read JSON from a URL in java

Read json from url use url.openStream() and read contents ...READ MORE

Jun 13, 2018 in Java by samarth295
 • 2,220 points • 4,928 views
0 votes
1 answer

What is the difference between hashset and treeset?

HashSet vs TreeSet: 1- Hashset gives better performance (faster) ...READ MORE

Jun 20, 2018 in Java by Akrati
 • 3,190 points • 4,613 views
0 votes
1 answer

Unescaping HTML character entities in Java

I guess you can use this function: StringEscapeUtils.unescapeH ...READ MORE

Sep 25, 2018 in Java by anto.trigg4
 • 3,440 points • 412 views
0 votes
1 answer

Can we convert a string to hexadecimal in java

I find this to be an easy ...READ MORE

Jul 4, 2018 in Java by Akrati
 • 3,190 points • 3,900 views
0 votes
1 answer

Why is the Scanner skipping nextLine() after using next() or nextFoo()

public static void main(String[] args) { ...READ MORE

Aug 28, 2018 in Java by samarth295
 • 2,220 points • 1,467 views
0 votes
2 answers

Java Environment Variables

--- To set java path --- There are ...READ MORE

Dec 3, 2018 in Java by Sushmita
 • 6,910 points • 1,264 views
0 votes
2 answers

How can I do url string decoding in java

We can use URLDecoder: URLDecoder.decode( url, "UTF-8" ); READ MORE

Dec 7, 2018 in Java by Sushmita
 • 6,910 points • 636 views
0 votes
1 answer

What are the Foreign key constraints in Android using SQLite

You can use, Foreign key constraints with ...READ MORE

Aug 24, 2018 in Java by geek.erkami
 • 2,680 points • 1,581 views
0 votes
2 answers

Ho do I Iterate through a HashMap which contains duplicate values

for (Map.Entry<String, String> item : params.entrySet()) { ...READ MORE

Jul 24, 2018 in Java by samarth295
 • 2,220 points • 4,926 views
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