How to get random range number in set

Question

I have 100 record [1 -> 100], i want get random 50 record in this, how to do in java? Thanks.

Answer 1

You can get 50 random values.

Random rand = new Random();

List ints = new ArrayList();
for(int i = 0; i < 50; i++)
    ints.add(rand.nextInt(100)+1);

You can get 50 unique values in a random order using shuffle.

List ints = new ArrayList();
for(int i = 1; i <= 100; i++)
    ints.add(i);
Collections.shuffle(ints);
ints = ints.subList(0, 50);