How to generate two random numbers out of 4?

Question

I need two random numbers out of 1, 2, 3 and 4, but they cannot be the same and I need them in two different variables.

So, something like rnd1 = 1; and rnd2 = 3; .

I tried to generate them classic style: int rnd = new Random().nextInt(3) + 1; . And for the other one the same way, but how to ensure that they don't match? How to do that?

Answer 1

Rather than implementing the randomness and unicity yourself, you could simply populate a list with the allowed numbers, shuffle it and take the first two entries:

List<Integer> list = Arrays.asList(1, 2, 3, 4);
Collections.shuffle(list);
rnd1 = list.get(0);
rnd2 = list.get(1);

Answer 2

Random random = new Random();
int rnd1 = random.nextInt(3) + 1;
int rnd2 = rnd1;
while(rnd2 == rnd1) {
    rnd2 = random.nextInt(3) + 1;
}

Answer 3

Well, the easiest way could be:

Random random = new Random();
int rnd1 = random.nextInt(3) + 1;
int rnd2;
do {
    rnd2 = random.nextInt(3) + 1;
} while (rnd1 == rnd2);

Answer 4

Assign the first value to the second then use a while loop until the two values are not equal.

int rnd = new Random().nextInt(3) + 1;
int rnd2 = rnd;

while(rnd2 == rnd){
  rnd2 = new Random().nextInt(3) + 1;
}

Answer 5

    int one, two;
    Random r = new Random();
    one = r.nextInt(3) + 1;
        two = r.nextInt(3) + 1;
    while (one == two){
            two = r.nextInt(3) + 1;