1 public class TestPerson {  2     public static void main(String[] args) {  3         Person p = new Person();  4         p.eat();  5         p.walk();  6   7         Man m = new Man();  8         m.eat();  9         m.walk(); 10         System.out.println(); 11  12         // 子类对象的多态性：父类的引用指向子类对象 13         Person p1 = new Man();// 向上转型 14         // 虚拟方法调用：通过父类的引用指向子类的对象实体，当调用方法时，实际执行的是子类重写父类的方法 15         p1.eat(); 16         p1.walk(); 17         System.out.println("$" + p1.id);//1001 18  19 //        p1.smoking = null; 20         // p1.entertainment(); 21  22         Person p2 = new Woman(); 23         p2.eat(); 24         p2.walk(); 25         // p2.shopping(); 26         Woman w = (Woman) p2;// 向下转型,使用强转符：() 27         w.shopping(); 28  29         // java.lang.ClassCastException 30         // Woman w1 = (Woman)p1; 31         // w1.shopping(); 32  33         // Woman w2 = (Woman)new Man(); 34         // instanceof: 35         // 格式： 对象a instanceof 类A：判断对象a是否是类A的一个实例.是的话，返回true；否则返回false 36         // 若a是A类的实例，那么a也一定是A类的父类的实例。 37         if (p1 instanceof Woman) { 38             System.out.println("hello!"); 39             Woman w1 = (Woman) p1; 40             w1.shopping(); 41         } 42  43         if (p1 instanceof Man) { 44             Man m1 = (Man) p1; 45             m1.entertainment(); 46         } 47  48         if (p1 instanceof Person) { 49             System.out.println("你好！"); 50         } 51  52     } 53  54     public void show(Person p) {//Person p = new Man(); 55  56     } 57  58  59  60 class Person { 61     private String name; 62     private int age; 63     int id = 1001; 64     public Person() { 65         super(); 66     } 67     public Person(String name, int age) { 68         super(); 69         this.name = name; 70         this.age = age; 71     } 72     public String getName() { 73         return name; 74     } 75     public void setName(String name) { 76         this.name = name; 77     } 78     public int getAge() { 79         return age; 80     } 81     public void setAge(int age) { 82         this.age = age; 83     } 84     85     public void walk(){ 86         System.out.println("人走路"); 87     } 88     public void eat(){ 89         System.out.println("人吃饭"); 90     } 91  92 } 93  94  95  96  97 class Man extends Person{ 98      boolean smoking; 99      int id = 1002;100     public Man() {101         super();102     }103    104     public Man(boolean smoking) {105         super();106         this.smoking = smoking;107     }108 109     public boolean isSmoking() {110         return smoking;111     }112 113     public void setSmoking(boolean smoking) {114         this.smoking = smoking;115     }116    117     public void walk(){118         System.out.println("男人笔挺的走路");119     }120     public void eat(){121         System.out.println("男人应该多吃肉！");122     }123    124     public void entertainment(){125         System.out.println("男人请客");126     }127 }128 129 130 class Woman extends Person{131     private boolean isBeauty;132 133     public boolean isBeauty() {134         return isBeauty;135     }136 137     public void setBeauty(boolean isBeauty) {138         this.isBeauty = isBeauty;139     }140 141     public Woman() {142         super();143     }144 145     public Woman(boolean isBeauty) {146         super();147         this.isBeauty = isBeauty;148     }149     public void walk(){150         System.out.println("女人窈窕的走路。。。");151     }152    153     public void eat(){154         System.out.println("女人应该少吃，减肥");155     }156     public void shopping(){157         System.out.println("女人爱购物");158     }159    160 }