Answers for "how to create random numbers in java, but they can't repeat"

generate random number in java within a range without repeating with android studio

public void NextRandom(View view) // button clicked function
    {
        int previousIndex = index;
        index = rand.nextInt(array.size());

        while (index == previousIndex)
        {
            index = rand.nextInt(array.size());
        }
    }