选择大于Integer.MAX_VALUE的范围内的随机整数? [英] Choose random integer in a range bigger than Integer.MAX_VALUE?

问题描述

我知道还有一个关于范围内随机性的问题，但是他们的答案都无法完成我想做的事情.实际上，它们具有与我相同的错误.我写了这个简单的函数来生成带范围的随机数.

I know there are another questions about random in a range but none of their answers accomplishes what I am trying to do. Actually they have the same error I have. I wrote this simple function to generate random with range.

Random m_random = new Random();
...
public int RandomWithRange(int min, int max) {
    return m_random.nextInt(max - min + 1) + min;
}

如果范围大于Integer.MAX_VALUE，则抛出IllegalArgumentException:n必须为正.我知道它溢出并变成负数.我的问题是如何处理?

If range is bigger than Integer.MAX_VALUE, it throws an IllegalArgumentException: n must be positive. I know it overflows and turn to a negative number. My question is how to handle that?

示例范围；

• [0，Integer.MAX_VALUE]
• [Integer.MIN_VALUE，Integer.MAX_VALUE]
• [-100，Integer.MAX_VALUE]

注意:最小值和最大值必须包含在内.

Note: min and max must be inclusive.

推荐答案

您遇到的问题是(max - min)溢出并为您提供负值.

The problem you have is that (max - min) overflows and gives you a negative value.

您可以改用long.

public int randomWithRange(int min, int max) {
    return (int) ((m_random.nextLong() & Long.MAX_VALUE) % (1L + max - min)) + min;
}

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