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 randomNum = 5 + (int)(Math.random()*5);

范围5-10

其他回答

我想知道Apache Commons Math库提供的任何随机数生成方法是否符合要求。

例如:RandomDataGenerator.nextInt或RandomDataGenerator.nextLong

以下是使用Random和forEach的另一个示例

int firstNum = 20;//Inclusive
int lastNum = 50;//Exclusive
int streamSize = 10;
Random num = new Random().ints(10, 20, 50).forEach(System.out::println);
Random rng = new Random();
int min = 3;
int max = 11;
int upperBound = max - min + 1; // upper bound is exclusive, so +1
int num = min + rng.nextInt(upperBound);
System.out.println(num);

下面是一个函数,它按照用户42155的请求,在lowerBoundIncluded和upperBoundIncluded定义的范围内返回一个整数随机数

SplitableRandom splitableRandom=新的Splitablerandom();

BiFunction<Integer,Integer,Integer> randomInt = (lowerBoundIncluded, upperBoundIncluded)
    -> splittableRandom.nextInt(lowerBoundIncluded, upperBoundIncluded + 1);

randomInt.apply(…,…);//获取随机数

…或更短,用于一次性生成随机数

new SplittableRandom().nextInt(lowerBoundIncluded, upperBoundIncluded + 1);

您可以使用以下方法来执行此操作:

int range = 10;
int min = 5
Random r = new Random();
int = r.nextInt(range) + min;