how to create an array of non-repeated rand numbers

Question

I would like to create a array having 21 values between 0 to 20.I would like them to be in random and at the same time non-repeated.

I know how to create a random number

Answer 1

You can use a Set to add rands until the size is 20, then dump to an array.

If you need performance, use Guava's HashSet or Trove's TIntSet.