java基础异常处理

异常的定义：中断了正常指令流的事件。

try..catch..finally结构：

class Test{
    public static void main(String[] args){
        System.out.println(1);
        try{
            System.out.println(2);
            int i = 1 / 0;
            System.out.println(3);
        }
        catch(Exception e){
            e.printStackTrace();
            System.out.println(4);
        }
        finally{
            System.out.println(5);
        }
        System.out.println(6);
    }
}

输出结果：

    D:\Java\code\练习十二>java Test
1
2
java.lang.ArithmeticException: / by zero
        at Test.main(Test.java:6)
4
5
6

　　

throw与throws关键字

class User{
	private int age;
	public void setAge(int age) throws Exception{
		if(age <= 0){
			Exception e = new Exception("input age is error!");
			throw e;
		}
		else{
			this.age=age;
		}

	}
}

　　

class Test{
    public static void main(String[] args){
        User u = new User();
        try{
            u.setAge(-20);
        }
        catch(Exception e){
            System.out.println(e);
        }

    }
}

D:\Java\code\练习十二>java Test
java.lang.Exception: input age is error!