How to create two lists with unique numbers?

Question

Java

Hello!
I need to do: Create 2 lists of 10 elements from 1 to 100. Check with what attempt you can create lists with unique values. how to implement it correctly?
What am I doing:

List<Integer> list1;
List<Integer> list2;
public void createList(){
    int chance = 0;
    while (!Collections.disjoint(list1, list2)){
        List<Integer> list1 = Collections.nCopies(10, rand.nextInt(100));
        List<Integer> list2 = Collections.nCopies(10, rand.nextInt(100));
        chance++;
    }
    list1.forEach(System.out::println);
    list2.forEach(System.out::println);
    System.out.println(chance);
}

Answer 1

You almost did everything right except that Collections.nCopies(10, rand.nextInt(100)); just picks one random number, and makes a list of 10 repetitions of that number. Wangyu that you immediately get lists of different elements on the first try (for example, [17,17,17,17,17,17,17,17,17,17] and [73,73,73,73, 73,73,73,73,73]).
It is necessary to fill the list in a loop, each time calling nextInt(100). Or use the Stream API and write something like

IntStream.range(0, 10).map(i -> rand.nextInt(100)).collect(Collectors.toList());

Answer 2

1. Make a list of 100 items (1, 2, 3...100).
2. Choose randomly from this list, deleting the selected items.
Get it right the first time.