[FIXED] Random generator creates the same numbers

Issue

While looping through a for loop which is randomly 1-10 long. I also go through a while loop. I am trying to find 6 random numbers between 1-42. I then do that again (1-10) times. Currently, these 6 random numbers stay the same. I suspect it has something to do with the seed but I could not solve it.

I tried to use both SecureRandom, Random, and via Math.random() Nothing has worked.

The model:

    public static final int MAX_TIPS = 10;
    public static final int MIN_TIPS = 1;
    public static final int REQUIRED_NUMBERS = 6;
    public static final int RANGE_NUMBER_MIN = 1;
    public static final int RANGE_NUMBER_MAX = 42;
    public static final int RANGE_LUCKY_NUMBER_MIN = 1;
    public static final int RANGE_LUCKY_NUMBER_MAX = 6;

    private Random random = new Random();

    private int getRandomInt(int min, int max) {
         return random.nextInt((max - min) + 1) + min;
    }

    public ArrayList<LottoTip> createOpponentTips() {
        ArrayList<Integer> opponentChosenNumbers = new ArrayList<>();
        ArrayList<LottoTip> lottoTips = new ArrayList<>();

        //1-10
        int amountOfTips = getRandomInt(MIN_TIPS, MAX_TIPS);

        for (int i = 0; i < amountOfTips; i++) {

            int[] arrayOpponentChosenNumbers = new int[REQUIRED_NUMBERS];

            while (opponentChosenNumbers.size() < REQUIRED_NUMBERS) {

                //1-42 This here is the problem zone

                int randomNumber = getRandomInt(RANGE_NUMBER_MIN, RANGE_NUMBER_MAX);
                if (!opponentChosenNumbers.contains(randomNumber)) {
                    opponentChosenNumbers.add(randomNumber);
                }
            }
            //1-6 ---This here works
            int opponentLuckyNumber = getRandomInt(RANGE_LUCKY_NUMBER_MIN, RANGE_LUCKY_NUMBER_MAX);

            for (int j = 0; j < opponentChosenNumbers.size(); j++) {
                arrayOpponentChosenNumbers[j] = opponentChosenNumbers.get(j);
            }

            lottoTips.add(new LottoTip(arrayOpponentChosenNumbers, opponentLuckyNumber));
        }

        return lottoTips;
    }

LottoTip:

public class LottoTip {
    private int[] numbers;
    private int luckyNumber;

    public LottoTip(int[] numbers, int luckyNumber) {
        this.numbers = numbers;
        this.luckyNumber = luckyNumber;
    }

    public String getNumbers() {
        return numbers[0] + ", " + numbers[1] + ", " + numbers[2] + ", " + numbers[3] + ", " + numbers[4] + ", " + numbers[5];
    }

    public void setNumbers(int[] numbers) {
        this.numbers = numbers;
    }

    public int[] getNumbersArray() {
        return numbers;
    }

    public int getLuckyNumber() {
        return luckyNumber;
    }

    public void setLuckyNumber(int luckyNumber) {
        this.luckyNumber = luckyNumber;
    }

    @Override
    public String toString() {
        return "\nNumbers: " + getNumbers() + " Lucky Number: " + luckyNumber;
    }
}

Here is a System.out.println as you can see the Numbers are staying the same. Could you help me find a way to create a getRandomInt method which works all the time?

Thank you very much for your help.

Kerry York [
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 2, 
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 4, 
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 5, 
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 1, 
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 3, 
Numbers: 6, 4, 30, 15, 25, 5 Lucky Number: 6]

Don Dickinson [
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 6, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 5, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 3, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 2, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 4, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 1, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 1, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 4, 
Numbers: 23, 29, 34, 18, 16, 19 Lucky Number: 3]

Clifford Weinstein [
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 6, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 3, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 2, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 1, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 4, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 3, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 5, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 6, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 3, 
Numbers: 6, 33, 13, 2, 37, 38 Lucky Number: 3]

Angela Spencer [
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 6, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 3, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 2, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 4, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 5, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 4, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 2, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 2, 
Numbers: 12, 39, 8, 25, 40, 15 Lucky Number: 3]

Leroy McIntosh [
Numbers: 5, 23, 2, 24, 28, 3 Lucky Number: 1]

Solution

You reuse the opponentChosenNumbers list between iterations of the outer for loop.

As such, on the second iteration, the while loop guard

while (opponentChosenNumbers.size() < REQUIRED_NUMBERS) {

is immediately false, so you don't pick new random numbers.

Move the declaration of opponentChosenNumbers into the for loop (or ensure it is empty before the while loop, e.g. by invoking opponentChosenNumbers.clear()).

Answered By - Andy Turner