如何在特定范围内生成随机int值?

以下方法存在与整数溢出相关的错误:

randomNum = minimum + (int)(Math.random() * maximum);
// Bug: `randomNum` can be bigger than `maximum`.
Random rn = new Random();
int n = maximum - minimum + 1;
int i = rn.nextInt() % n;
randomNum =  minimum + i;
// Bug: `randomNum` can be smaller than `minimum`.

当前回答

int func(int max, int min){

      int range = max - min + 1;
      
      // Math.random() function will return a random no between [0.0,1.0).
      int res = (int) ( Math.random()*range)+min;

      return res;
}

其他回答

要生成“介于两个数字之间”的随机数,请使用以下代码:

Random r = new Random();
int lowerBound = 1;
int upperBound = 11;
int result = r.nextInt(upperBound-lowerBound) + lowerBound;

这将为您提供一个介于1(含)和11(不含)之间的随机数,因此通过添加1来初始化上限值。例如,如果要生成1到10之间的随机数,则使用11而不是10初始化上限数。

您可以在Java 8中简洁地实现这一点:

Random random = new Random();

int max = 10;
int min = 5;
int totalNumber = 10;

IntStream stream = random.ints(totalNumber, min, max);
stream.forEach(System.out::println);

Use:

minValue + rn.nextInt(maxValue - minValue + 1)
public static Random RANDOM = new Random(System.nanoTime());

public static final float random(final float pMin, final float pMax) {
    return pMin + RANDOM.nextFloat() * (pMax - pMin);
}
Random random = new Random();
int max = 10;
int min = 3;
int randomNum = random.nextInt(max) % (max - min + 1) + min;