Generating unique random number in java [duplicate

Question

This question already has an answer here:

• Generating Unique Random Numbers in Java 17 answers

I want to generate random number from 1 to 9 and i want them to be unique. This is the code i have written which gives me 9 different numbers from 1 to 9 but I have no clue on generating unique number.

 int data[] = new int[10];
      for(int i = 0; i < data.length; i++) {
            Random randomGenerator = new Random();

            data[i] = randomGenerator.nextInt(10);
          System.out.println(data[i]);

        }

Answer 1

Fill a List<Integer> list with 1..9 and then:

Collections.shuffle(list);

Note that to fill an array of 10, you'll have to have one duplicate.

Answer 2

1. Store 1 to 9 numbers in an Array.

2. Generate random number between 1 to 9 as position and return array[position-1] to get the value

3. Once you use a number in array, mark the value as -1.

4. If value in array is -1, get the random number again