instanceof运算符

来源：互联网发布：网络暴力的现状编辑：程序博客网时间：2024/06/06 06:51

instance是java的二元运算符，用来判断他左边的对象是否为右面类（接口，抽象类，父类）的实例

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
interfaceA{
     
}
classB implementsA{
      
}
classC extendsB{
      
}
publicclass Iinstanceof {
 
    publicstatic void main(String[] args) {
        A ab=newB();
        A ac=newC();
        B bc=newC();
        B bb=newB();
        C cc=newC();
        //对象实现一个接口，用这个对象和这个接口进行instanceof判断，都为true。
        System.out.println("ab instanceof A="+(ab instanceofA));
        System.out.println("ac instanceof A="+(ac instanceofA));
        System.out.println("bc instanceof A="+(bc instanceofA));
        System.out.println("bb instanceof A="+(bb instanceofA));
        System.out.println("cc instanceof A="+(cc instanceofA));
        //对象和父类进行instanceof判断，都为true
        System.out.println("ab instanceof B="+(ab instanceofB));
        System.out.println("ac instanceof B="+(ac instanceofB));
        System.out.println("bc instanceof B="+(bc instanceofB));
        System.out.println("bb instanceof B="+(bb instanceofB));
        System.out.println("cc instanceof B="+(cc instanceofB));
        //对象和他的子类进行instanceof判断为false
        System.out.println("ab instanceof C="+(ab instanceofC));
        System.out.println("ac instanceof C="+(ac instanceofC));
        System.out.println("bc instanceof C="+(bc instanceofC));
        System.out.println("bb instanceof C="+(bb instanceofC));
        System.out.println("cc instanceof C="+(cc instanceofC));
    }
}

程序输出：
ab instanceof A=true
ac instanceof A=true
bc instanceof A=true
bb instanceof A=true
cc instanceof A=true
ab instanceof B=true
ac instanceof B=true
bc instanceof B=true
bb instanceof B=true
cc instanceof B=true
ab instanceof C=false
ac instanceof C=true
bc instanceof C=true
bb instanceof C=false
cc instanceof C=true

0 0