046_面向对象_19_内存分析

一、关于多态的演示示例

　　

package edu.aeon.test;
/**
 * [说明]:动物类
 * @author aeon
 *
 */
public class Animal {
    String str;

    public void voice() {
        System.out.println("普通动物叫声！");
    }
}

class Cat extends Animal {
    public void voice() {
        System.out.println("喵喵喵");
    }

    public void catchMouse() {
        System.out.println("抓老鼠");
    }
}

class Dog extends Animal {
    public void voice() {
        System.out.println("汪汪汪");
    }

    public void seeDoor() {
        System.out.println("看门！");
    }
}

class Tiger extends Animal {
    public void voice() {
        System.out.println("哇哇哇");
    }

}

class Pig extends Animal {
    public void voice() {
        System.out.println("哼哼哼");
    }
}

package edu.aeon.test;
/**
 * [说明]:测试多态
 * @author aeon
 *
 */
public class Test {
    public static void testAnimalVoice(Animal c) {
        c.voice();
        if (c instanceof Cat) {
            ((Cat) c).catchMouse();
        }
    }

    public static void main(String[] args) {
        Animal a = new Cat();
        Cat a2 = (Cat) a;
        testAnimalVoice(a);
    }
}

该示例在内存中的结构图如下：

　　

运行结果截图：