Welcome to the Java Programming Forums

The professional, friendly Java community. 21,500 members and growing!

The Java Programming Forums are a community of Java programmers from all around the World. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. We invite beginner Java programmers right through to Java professionals to post here and share your knowledge. Become a part of the community, help others, expand your knowledge of Java and enjoy talking with like minded people. Registration is quick and best of all free. We look forward to meeting you.


Members have full access to the forums. Advertisements are removed for registered users.

View RSS Feed

All Blog Entries

  1. Optimizing the Sieve of Eratosthenes

    The Sieve of Eratosthenes is one of the fastest methods for generating a list of prime numbers less than a given number n. A general description of the algorithm is given below:

    1. Initialize a list representing the numbers [2,n). This denotes whether a given number is prime or composite.
    2. Start from the beginning of the list. If the number is denoted as prime, save it. Otherwise, move on.
    3. For every multiple of the current prime, mark it as a composite number. ...

    Updated September 29th, 2012 at 18:26 by helloworld922

  2. Preview: 2D Grid Accelerator Structure

    This is a short preview of 2D grid accelerator structure. It's primary use is for speeding up collision detection.

    The general concept is this:

    The full 2D space is partitioned into individual grid (the black lines). Each shape added to the grid has some minimal aligned bounding box (pictured as green outlines). Every grid square which overlaps this bounding box has the shape's reference added to it's list of shapes (red background). Now to check for collisions, you ...

    Updated April 8th, 2012 at 22:59 by helloworld922

  3. Thread Volatility

    This is put at the top for those who don't want to read the entire thing.
    • Threads get more volatile as more are added, up to a point
    • Thread volatility jumps drammatically on my computer between 4 and 8 threads.
    • Calling non-volatile variables is very inaccurate

    I recently posted a forum thread that more Java Threads will increase volatility. While I had seen the side-effect volatility and it seemed intuitive enough, I decided that n order ...

    Updated March 13th, 2012 at 14:26 by Tjstretch

  4. Enhanced For Statement - JavaDevelopmentForums.com

    by , January 29th, 2012 at 16:08 (JD1's Personal Development Blog)
    When working with arrays, there's an easier way to loop through the indices than manually doing so. We can use the enhanced for statement for this.

    class Class1{
       public static void main(String args[]){
    	   int aryOne[] = {3,4,5,6,7};
    	   int total = 0;
    	   for (int x: aryOne){
    		   total += x;

    First of all, we create our array (aryOne) and use ...
  5. Array Elements As Counters - JavaDevelopmentForums.com

    by , January 29th, 2012 at 16:07 (JD1's Personal Development Blog)
    We're going to build a program to re-enact a dice being rolled one thousand times. We're going to output how many times each face of the dice is rolled.

    import java.util.Random;
    class RollDice{
       public static void main(String args[]){
    	   Random rand = new Random();
    	   int freq[] = new int[7];
    	   for(int roll = 1; roll <= 1000; roll++){
    		   ++freq[1 + rand.nextInt(6)];
Page 3 of 14 FirstFirst 1234513 ... LastLast