java - 为什么我的数字在前 100000 个方格中的结果是负数？

Question

我必须创建一个代码来显示前 100000 个数字的平方，并测量程序显示每个数字所花费的时间。在我的结果中，数字有时会变为负数，然后再次变为正数。为什么是这样？我应该如何更改我的代码以使我的结果不是负面的？ (前 1000 个平方数或 10000 不会发生这种情况)。

package assignment.pkg5;

import java.util.Calendar;

public class LoopsLab1000001b {
    public static void main(String[] args) {
        long time_start, time_finish;
        time_start = time();

        int count = 1;
        while (count <= 100000) {
            System.out.println(count * count);
            count++;
        }

        time_finish = time();

        System.out.println(time_finish - time_start + " milli seconds");

    }

    public static long time() {
        Calendar cal = Calendar.getInstance();
        return cal.getTimeInMillis();
    }
}

Answer 1

整数溢出。参见 wiki ，具体来说:

In some situations, a program may make the assumption that a variable always contains a positive value. If the variable has a signed integer type, an overflow can cause its value to wrap and become negative. This overflow violates the program's assumption and may lead to unintended behavior.