java对象转型

java对象转型

TestCasting.java

//对象转型——实例1
class Animal {
	public String name;//名字
	
	Animal(String name) {
		this.name = name;
	}
}

class Cat extends Animal {
	public String eyeColor;//眼睛的颜色
	
	Cat(String name, String eyeColor) {
		super(name);
		this.eyeColor = eyeColor;
	}	
}

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

public class TestCasting {
	public static void main(String[] args) {
		Animal a = new Animal("name");
		Cat c = new Cat("CatName","bule");
		Dog d = new Dog("DogName","black");
		
		//instanceof用来判断内存中实际对象A是不是B类型
		System.out.println(a instanceof Animal);//a是Ainmal吗？true
		System.out.println(c instanceof Animal);//true
		System.out.println(d instanceof Animal);//true		
		System.out.println(a instanceof Cat);//a是Cat吗？false
		
		a = new Dog("大黄","黄色");
		System.out.println(a.name);//大黄
		//System.out.println(a.furColor);//error
		System.out.println(a instanceof Animal);//a是Ainmal吗？true
		System.out.println(a instanceof Dog);//a是Dog吗？true
		
		Dog d1 = (Dog)a;//要加强制转换符
		System.out.println(d.furColor);//black
		
		/***************************************************************/
		TestCasting test = new TestCasting();
		test.f(a);	//name: 大黄 黄色 fur
		test.f(c);	//name: CatName bule eyes
		test.f(d);	//name: DogName black fur
	
	}
	
	//面向对象，可扩展性好
	public void f(Animal a) {
		System.out.print(" name: " + a.name);
		if(a instanceof Cat) {
			Cat cat = (Cat)a;			
			System.out.println(" " + cat.eyeColor + " eyes");
		} else if(a instanceof Dog){
			Dog dog = (Dog)a;
			System.out.println(" " + dog.furColor + " fur");
		}
	}
}