JAVA基础-多态

多态 polymophism: 动态绑定, 迟绑定, 指在执行期间(java), 而不是编译期间(javac), 判断所引用对象的实际类型, 根据实际类型调用响应的方法.

3个条件: 1. 继承 2. 重写 3. 父类引用指向子类对象

优点: 可扩展

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

  public void enjoy(){
    System.out.println("叫声......");
  }

  //public abstract void enjoy();
}

//abstract 
class Cat extends Animal {
  private String eyesColor;
  Cat(String n,String c) {super(n); eyesColor = c;}

  public void enjoy() {
    System.out.println("猫叫声......");
  }

  //public abstract void enjoy();
}

class Dog extends Animal {
  private String furColor;
  Dog(String n,String c) {super(n); furColor = c;}

  public void enjoy() {
    System.out.println("狗叫声......");
  }
}

class Bird extends Animal {
	 Bird() {
	 	 super("bird");
	 }
	 public void enjoy() {
    System.out.println("鸟叫声......");
  }
}

class Lady {
    private String name;
    private Animal pet;
    Lady(String name,Animal pet) {
        this.name = name; this.pet = pet;
    }
    public void myPetEnjoy(){pet.enjoy();}
}

public class Test {
    public static void main(String args[]){
        Cat c = new Cat("catname","blue");
        Dog d = new Dog("dogname","black");
        Bird b = new Bird();
        Lady l1 = new Lady("l1",c);
        Lady l2 = new Lady("l2",d);
        Lady l3 = new Lady("l3",b);
        l1.myPetEnjoy();
        l2.myPetEnjoy();
        l3.myPetEnjoy();
    }
}