Question

I have the following code to create a random series of a numbers from 0 to a given amount.

ArrayList<Integer> places = new ArrayList<Integer>();
for (int cnt = 0; cnt < NUMBER; cnt++) {
    int place = (int)(random.nextDouble()*places.size());
    places.add(place , new Integer(cnt));
}

I use this code in a method and then I run this method for about 1000 times for statistics purposes.
My problem is that created series is the same for all of the 1000 time.
Every time that I run the sequence is different, but same for all of the for values.
What should I do? Is there a method like srand() in C++?

Answer 1

Your algorithm seems flawed if you are trying to generate an array with numbers 0 ... NUMBER-1 in random order. Consider:

Random rnd = new Random(System.currentTimeMillis());
...
ArrayList<Integer> places = new ArrayList<Integer>(NUMBER);
for (int i = 0; i < NUMBER; ++i) {
  places.add(i);
}
Collections.shuffle(places, rnd);