21.多态

父类
public class Animal {
    public String name = "小动物";

    public void dosomething() {
        System.out.println("动物都要吃东西!!!");
    }
}
子类
public class Dog extends Animal {
    public String name = "旺旺";
    public int age = 11;

    @Override
    public void dosomething() {
        System.out.println("狗吃屎!!!");
    }

    public void eat() {
        System.out.println("eat");
    }
}
执行:
public class Demo {

    public static void main(String[] args) {
        Animal animal = new Dog();
        System.out.println(animal.name);
//        System.out.println(animal.age);编译报错,因为Animal类里面没有age变量
        animal.dosomething();
//        animal.eat();编译报错,因为Animal类里面没有eat方法
    }

}