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javarandomintegerunique

Unique Random Integer Generator

I'm trying to make a random Integer generator that produces unique numbers.

Does anyone has any ideas how's that possible?

Solution

  • If you have a small-enough range of possible numbers, then this is very simple and useful:

    final List<Integer> sack = new ArrayList<>(RANGE);
for (int i = 0; i < RANGE; i++) sack.add(i);
Collections.shuffle(sack);

    Now just pull items out of sack in order.