JAVA笔记8-对象转型casting

public class TestAnimal{
    public static void main(String args[]){
        Animal a=new Animal("name");
        Dog d=new Dog("dogname","black");
        Cat c=new Cat("catname","blue");
        System.out.println(a instanceof Animal);//true
        System.out.println(d instanceof Animal);//true
        System.out.println(c instanceof Cat);//true
        System.out.println(a instanceof Cat);//false
        a=new Dog("bigyellow","yellow");//父类引用指向子类对象（向上转型）
        System.out.println(a.name);//bigyellow
        //System.out.println(a.furColor);//编译错误：找不到符号！规则（2）
        System.out.println(a instanceof Animal);//true
        System.out.println(a instanceof Dog);//true！！！
        Dog d1=(Dog) a;//强制转换符（向下转型）
        System.out.println(d1.furColor);//yellow
        //Cat c1=(Cat) a;//运行时抛异常！java.lang.ClassCastException:Dog cannot be cast to Cat
    }
}

class Animal{
    public String name;
    Animal(String name){
        this.name=name;
    }
}

class Dog extends Animal{
    public String furColor;
    Dog(String name,String furColor){
        super(name);
        this.furColor=furColor;
    }
}

class Cat extends Animal{
    public String eyesColor;
    Cat(String name,String eyesColor){
        super(name);
        this.eyesColor=eyesColor;
    }
}

public class TestAnimal{
    public static void main(String args[]){
        TestAnimal test=new TestAnimal();
        Animal a=new Animal("name");
        Dog d=new Dog("dogname","black");
        Cat c=new Cat("catname","blue");
        test.f(a);
        test.f(c);
        test.f(d);
    }
    public void f(Animal a){
        System.out.println("name:"+a.name);
        if(a instanceof Cat){
            Cat c1=(Cat) a;
            System.out.println(" "+c1.eyesColor+" eyes");
        }
        else if(a instanceof Dog){
            Dog d1=(Dog) a;
            System.out.println(" "+d1.furColor+" fur");
        }
    }
}

class Animal{
    public String name;
    Animal(String name){
        this.name=name;
    }
}

class Dog extends Animal{
    public String furColor;
    Dog(String name,String furColor){
        super(name);
        this.furColor=furColor;
    }
}

class Cat extends Animal{
    public String eyesColor;
    Cat(String name,String eyesColor){
        super(name);
        this.eyesColor=eyesColor;
    }
}