断言练习

package com.zyq;

public class AssertTest01 {
    //这个成员变量的值可以变，但最终必须还是回到原值5
    static int i = 5;
    public static void main(String[] args) {
        assert i==6;
        System.out.println("如果断言正常，我就被打印");
    }
}
运行结果：

　　Exception in thread "main" java.lang.AssertionError
　　at com.zyq.AssertTest01.main(AssertTest01.java:7)

=================================================================================================

package com.zyq;

public class AssertTest02 {
    public static void main(String[] args) {
        int i = 3;
        switch (i) {
            case 1:
                System.out.println("正常");
                break;
            case 2:
                System.out.println("正常");
                break;
            case 5:
                System.out.println("正常");
                break;
            default:
                assert false:"i的值无效";       //如果i的值不是你想要的，程序就警告退出
        }
        System.out.println("如果断言正常，我就被打印");
    }
}
运行结果:

　　Exception in thread "main" java.lang.AssertionError: i的值无效
　　at com.zyq.AssertTest02.main(AssertTest02.java:17)