java入门第二季–多态–java中的多态

java中的多态

引用的多态
/javaDemo4/src/com/imooc/Animal.java
package com.imooc;

public class Animal {

}

/javaDemo4/src/com/imooc/Dog.java
package com.imooc;

public class Dog extends Animal {

}

/javaDemo4/src/com/imooc/Initail.java
package com.imooc;

public class Initail {

public static void main(String[] args) {

Animal obj1 = new Animal();
Animal obj2 = new Dog(); //父类的引用是可以指向子类对象
//Dog obj3 = new Animal(); //报错

}

}

方法多态
/javaDemo4/src/com/imooc/Animal.java
package com.imooc;

public class Animal {
public void eat() {
System.out.print(“动物具有吃的能力”);
}
}

/javaDemo4/src/com/imooc/Dog.java
package com.imooc;

public class Dog extends Animal {
public void eat() {
System.out.print(“狗具有吃肉的能力”);
}
public void watchDoor() {
System.out.print(“狗具有看门的能力”);
}
}

/javaDemo4/src/com/imooc/Initail.java
package com.imooc;

public class Initail {

public static void main(String[] args) {
// TODO Auto-generated method stub
Animal obj1 = new Animal();
Animal obj2 = new Dog(); //父类的引用是可以指向子类对象
//Dog obj3 = new Animal(); //报错
Animal obj3 = new Cat();
obj1.eat();

obj2.eat();
obj3.eat();
// obj2.watchDoor();
}

}