Java: Filling an array with random numbers without duplicates [duplicate]

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• How to shuffle the contents of an array 3 answers

I'm trying to fill an array with random numbers. There must be unique. I've tried this:

int random(int[] arr) {
    int number = 0;
    for (int i = 0; i < arr.length; i++) {
        Random rn = new Random();
        number = rn.nextInt(100);
        for (int j = i; j>0; j--) {
            if(arr[j]==zahl){
                random(arr);
            }
        }
    }
    return number;
}

I would be thankfull if you could help with my problem.