多态接口抽象类

多态：
同一个对象在不同时刻表现出来的不同形态。
前提：

List item存在继承/实现关系
存在方法重写

父类引用指向子类对象
多态中成员访问特点
使用多态时，访问成员变量的特点：
编译看左边，运行看左边
使用多态时，访问成员方法的特点：
编译看左边，运行看右边

public class Animal{
public int age=40;
public void eat(){
    System.out.println("动物吃东西");
}
    }
    public static Cat extends Animal{
		oublic int age=20;
		public int weight =10;
		@Override
		public void eat(){
		 System.out.println("猫吃鱼");
		}
		  public void playGame(){
    System.out.println("猫捉迷藏");
    }
}
public class AnimalDemo {
    public static void main(String[] args) {
        //有父类引用指向子类对象
        Animal a = new Cat();
        System.out.println(a.age);
        //System.out.println(a.weight);
        a.eat();
        //a.playGame();
        //成员变量编译执行都看左边，成员方法编译看左边，执行看右边
        //因为成员方法有重写，成员变量没有
    }
}

public class Animal{
public void eat(){
    System.out.println("动物吃东西" );
    }
}
public  class Cat extends Animal{
    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }
}
public  class Dog extends Animal{
    public void lookHome(){
        System.out.println("狗看家");
    }
}
 public class AnimalOpeart{
   /*public  void useAnimal(Cat c){
       c.eat();
   }
   public void useAnimal(Dog d){
       d.eat();
   }*/
   //把Animal a 传入这个方法  解决不同子类传入动作类的问题
  public void useAnimal(Animal a){
      a.eat();
  }
}
	public class AnimalDemo{
     public static void main(String[] args) {
          AnimalOpeart ao=new AnimalOpeart();
          Cat c=new Cat();
          ao.useAnimal(c);
          c.eat();

          Dog d=new Dog();
          ao.useAnimal(d);
          d.lookHome();
     }
}

public class Animal {

public void eat() {
    System.out.println("动物吃东西");
}

}
public class Cat extends Animal {

    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }

    public void playGame() {
        System.out.println("猫捉迷藏");
    }
}
public class Dog extends Animal {

    @Override
    public void eat() {
        System.out.println("狗吃骨头");
    }
}
public class AnimalDemo {
    public static void main(String[] args) {
        //向上转型
        Animal a = new Cat();
        a.eat();
        //向下转型
        Cat c = (Cat) a;
        c.eat();
        c.playGame();
        //向上转型
        a = new Dog();
        a.eat();
        //向下转型
 //classCastException   类型转换异常
        // Cat cc=(Cat) a;
        // cc.eat();
        //cc.playGame();
    }
}

public class Animal {
    private String name;
    private int age;

    public Animal() {
    }

    public Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
    public void eat(){
        System.out.println("动物吃东西");
    }
}
public class Cat extends Animal {
    public Cat() {
    }

    public Cat(String name, int age) {
        super(name, age);
    }

    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }
}
public class Dog extends Animal{
    public Dog() {
    }

    public Dog(String name, int age) {
        super(name, age);
    }

    @Override
    public void eat() {
        System.out.println("狗吃骨头");
    }
}
public class AnimalDemo {
    public static void main(String[] args) {
        Animal a =new Cat();
        a.setName("加菲猫");
        a.setAge(5);
System.out.println(a.getName()+","+a.getAge());
        a.eat();

        a=new Cat("大花猫",6);
        System.out.println(a.getName()+","+a.getAge());
        a.eat();
        System.out.println("--------------");

        Animal d=new Dog();
        d.setName("二哈");
        d.setAge(6);
        System.out.println(d.getName()+","+d.getAge());
       d.eat();
        d=new Dog("大黄",5);        System.out.println(d.getName()+","+d.getAge());
        d.eat();
    }
}

多态 接口 抽象类

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