Question

我已将我的字符串just_numbers转换为具有以下格式的数组格式：

System.out.println("just_numbers" + Arrays.toString(just_numbers));

看起来像[28, 27, 49, 25, 2, 23, 48, 18, 57, 58, 60, 20]

如何从上面选择3个随机数？顺序并不重要。

现在我正在尝试：

            Random random = new Random();

            //make random numbers
            int number1 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
            int number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
            int number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);

            while (number1 != number2 && number1 != number3) {
              number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
              number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);

            }

            System.out.println("random numbers are :" + number1 + " " + number2  + " " + number3);

但是我仍然得到类似的东西：

            random numbers are : 25 25 58

即-重复，每个数字应只列出一次。

Answer 1

private Integer[] getThreeRandomNumber() {
    HashSet<Integer> integers = new HashSet<>(3);
    Random random = new Random();
    while (integers.size() < 3) {
   // add number generation logic below
integers.add(Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]));
    }
    return integers.toArray(new Integer[3]);
}

Answer 2

根据您编写的代码，结果是正确的。问题在这条线上

while (number1 != number2 && number1 != number3) {
              number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
              number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
}

当数字不等于2或3时，您会寻找新值，但是当number1 等于2或3时，您应该查找新值。另外，将其设为or语句（一种更好的方法如下）

bool running = true; while(running){ running = false; // stop running if the code passes all checks if ( a == b || a == c){ a = Integer.ParseInt(...) //new random number running = true; } if ( b == c ){ b = Integer.ParseInt(...) // new random number running = true; } }

Answer 3

    ArrayList<Integer> numbers = new ArrayList<>();
    List<Integer> arrayIntegers = new ArrayList<>(Arrays.asList(28, 27, 49, 25, 2, 23, 48, 18, 57, 58, 60, 20));
    Random randomGenerator = new Random();
    while (numbers.size() < 3) {
        int random = randomGenerator .nextInt(arrayIntegers.size());
        if (!numbers.contains(arrayIntegers.get(random))) {
            numbers.add(arrayIntegers.get(random));
        }
    }
    System.out.print(" random numbers "+numbers);

Answer 4

在while循环中，条件无法完成您期望的操作。让我们从字面上解释循环：只要第一个数字与第二个数字不同，并且它也与第三个数字不同，请为number2和number3选择另一个随机数

由于条件number1!=number2将为false，因此将执行循环内的指令，直到第一个数字等于第二个数字为止。

请记住，数字1可以与数字2和数字3不同，但这不能防止数字2等于数字3。那里没有条件可以验证。

所以您的循环应该这样：

while (number1 == number2 || number1 == number3||number2 == number3) {
if(number1 == number2){
              number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
              }
              if(number1 == number3)
              {
              number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
              }

              if(number2 == number3)
              {
              number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
              }

            }

Answer 5

问题出在一段时间内，因为在以下情况下，您必须计算新的数字

n1等于n2 OR
n1等于n3 OR
n2等于n3 OR

所以你应该使用类似的东西

while ((number1 == number2) || (number1 == number3) || (number3 == number2))

这里的完整代码与您的问题尽可能相似：

String[] just_numbers = {"28", "27", "49", "25", "2", "23", "48", "18", "57", "58", "60", "20"};
    Random random = new Random();

        //make random numbers
        int number1 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
        int number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
        int number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);

        while ((number1 == number2) || (number1 == number3) || (number3 == number2)) {
          number2 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);
          number3 = Integer.parseInt(just_numbers[random.nextInt(just_numbers.length)]);

        }

        System.out.println("random numbers are :" + number1 + " " + number2  + " " + number3);

Answer 6

int[] arr  = {28, 27, 49, 25, 2, 23, 48, 18, 57, 58, 60, 20};
        Random random = new Random();
        List<Integer>  used = new ArrayList();
        used.add(random.nextInt(arr.length));

        while (true && used.size() <= 3){
            int temp = random.nextInt(arr.length);
            if(!used.contains(temp)){
                used.add(temp);
            }
        }

        System.out.println(arr[used.get(0)] + " " + arr[used.get(1)] + " " + arr[used.get(2)] + " ");

如何从该字符串返回一些随机数？

6 个答案: