8.16 instanceof 关键词

demo1

class Person {
    public void run(){
        System.out.println("run.....");
    }
}

class Superman extends Person {
    public void fly(){
        System.out.println("超音速飞....");
    }
    public void fire(){
        System.out.println("喷火");
    }
}

public class HelloWorld {
    public static void main(String args[]){
        Person per = new Person();
        System.out.println(per instanceof Person);// true
        System.out.println(per instanceof Superman);// false
    }
}

demo2 向上转型

class Person {
    public void run(){
        System.out.println("run.....");
    }
}

class Superman extends Person {
    public void fly(){
        System.out.println("超音速飞....");
    }
    public void fire(){
        System.out.println("喷火");
    }
}

public class HelloWorld {
    public static void main(String args[]){
        Person per = new Superman();// 向上转型
        System.out.println(per instanceof Person);// true
        System.out.println(per instanceof Superman);// true
    }
}

demo3 向下转型---解决安全隐患

class Person {
    public void run(){
        System.out.println("run.....");
    }
}

class Superman extends Person {
    public void fly(){
        System.out.println("超音速飞....");
    }
    public void fire(){
        System.out.println("喷火");
    }
}

public class HelloWorld {
    public static void main(String args[]){
        Person per = new Superman();// 向上转型
        if(per instanceof Superman){
            Superman man = (Superman) per;// 判断过后再向下转型;
            man.fly();
            man.fire();
        }
    }
}