Question

Possible Duplicate:
Java random always returns the same number when I set the seed?

In my game there is 4 monsters which are moving to the same random generated coordinates. It means random is not working.

 public void run() {
    while (true) {

                    // paints all Sprites, and graphics
        updateScreen(getGraphics());

        try {
            Thread.sleep(sleep);

        } catch (Exception e) {
        }
    }
}


private void updateScreen(Graphics g) {

     loops through all monsters and moves them a bit
     for (int gi = 0; gi < bottX.length; gi++) {

      bot(gi); // moves a  specified monster or gets new coordinates
     }

}

private void bot(int c) {

// some stuff to move a monster



 // if a monster is in desired place, generate new coordinates

    if(isInPlace()){
       // g]randomly generates new coordinates X and Y
        botX(c);
    botY(c);

    }


 }



public void botX(int c) {

           // monsters walking coordinates are between 30 px from the spawn zone.
    Random r1 = new Random();
    int s = r1.nextInt(3);
    // number 0 - left 1 - right 2 - don`t go in X axis
            // monster spawn coordinate
    int botox = spawnnX[c];
    int einamx;


    if (s == 0) {

        einamx = r1.nextInt(30) + (botox - 30); 
                    // [botox-30; botox)
    } else if (s == 1) {
        einamx = r1.nextInt(29) + (botox + 1); // (botoX+1 botoX+30]
    } else {
        einamx = botox;
    }



            // sets to where the monster should go
    einammX[c] = einamx;
    return;




          }

So in this game is 4 monsters which spawn coordinates are equals and you can only see 1 monter because they are moving the same. BTW if I set spawn coordinates different i can see 4 monsters which are moving the same.

Answer 1

Try to create one Random and reuse that instead of creating a new every time (if you have multiple threads create one per thread).