Random returning same values for all threads?

Question

<p>I "translated" an Applet example from a book to a MIDlet (as part of my learning process). However the MIDlet does not react as it should, and when the particles are all moving independently in the Applet, they are stuck together (as one) in the MIDlet.</p>
<p>So far, only one possibility was suggested to me: if the Random object are created one after the other, they could end up based on the same seed (which is the clock by default) and will generate the same numbers.</p>
<p>I tried to delay between the creation of the threads with no result. And the fact that the applet runs properly makes me wonder...</p>
<p>Does anyone have a clue?</p>
<p>In the MIDlet:</p>
protected Thread makeThread(final Particle p) { // utility
    Runnable runloop = new Runnable() {
      public void run() {
        try {
          for(;;) {
            p.move();
            canvas.repaint();
            Thread.sleep(100); // 100msec is arbitrary
        catch (InterruptedException e) {  return; }
    return new Thread(runloop);
  }<p>In the particle:</p>
protected final Random rng = new Random();
  public synchronized void move() {
    x += rng.nextInt(step) - (step/2);
    y += rng.nextInt(step) - (step/2);
    //returns exactly the same 10 times in a row
  }

Answer 1

You might try justing just one static Random object.
Also note that als long as your using CLDC 1.0, you don't have any floating point support.