生成count个[0-n)不重复的随机数

public static ArrayList getDiffNo(int count, int n){
    // 生成count个[0-n) 不重复的随机数，左开右闭
    // list 用来保存这些随机数
    ArrayList list = new ArrayList();
    Random rand = new Random();
    boolean[] bool = new boolean[n];
    int num = 0;
    for (int i = 0; i < count; i++) {
        do {
            // 如果产生的数相同继续循环
            num = rand.nextInt(n);
        } while (bool[num]);
        bool[num] = true;
        list.add(num);
    }
    return list;
}

for (int i = 0; i < 10; i++) {
            System.out.println(getDiffNo(5, 20));;
        }

[4, 0, 8, 9, 13]
[6, 13, 8, 10, 14]
[16, 6, 17, 12, 19]
[3, 10, 13, 4, 14]
[10, 0, 1, 5, 19]
[1, 14, 5, 11, 6]
[1, 3, 5, 9, 18]
[0, 5, 10, 4, 7]
[4, 5, 19, 10, 16]
[6, 13, 11, 3, 18]