当给变量分配的值小于该变量的最小允许值时,就会发生下溢。如果Java中发生下溢,那么JVM 不会抛出任何异常,并且程序员有责任处理下溢情况。
public class UnderlowTest { public static void main(String[] args) { int num1 = -2147483648; int num2 = -1; System.out.println("Number 1: " + num1); System.out.println("Number 2: " + num2); long sum = (long)num1 + (long)num2; if(sum < Integer.MIN_VALUE) { throw new ArithmeticException("发生下溢!"); } System.out.println("The sum of two numbers : " + (int)sum); } }
输出结果
Number 1: -2147483648 Number 2: -1 Exception in thread "main" java.lang.ArithmeticException: 发生下溢! at UnderlowTest.main(UnderlowTest.java:9)