1 package pet_2;

 2

 3 public  class Pet {

 4      private String name;

 5

 6   public String getName() {

 7     return name;

 8   }

 9

10   public void setName(String name) {

11     this.name = name;

12   }

13 }

14

15

16 package pet_2;

17

18 public class Dog extends Pet {

19

20      public void play() {

21        System.out.println("狗玩盘子");

22      }

23 }

24

25

26 package pet_2;

27

28 public class Cat extends Pet {

29

30    public void play() {

31        System.out.println("猫抓老鼠");

32      }

33 }

34

35

36 package pet_2;

37

38 public class Master {

39        public static Pet getPet(int typeid) {//静态方法可以直接类名调用,无需实例化一个对象

40          Pet pet=null;

41          if(typeid==1) {

42            pet=new Cat();//or Cat cat=new Cat();

43          }else if(typeid==2) {

44            Dog dog=new Dog();

45            pet=dog;

46          }

47

48          return pet;

49        }

50

51        public void play(Pet pet) {

52          //if(如果pet是dog) instanceof

53          if(pet instanceof Dog) {

54            Dog dog=(Dog)pet;

55            dog.play();

56          }

57          if(pet instanceof Cat) {

58            Cat cat=(Cat)pet;

59            cat.play();

60          }

61        }

62 }

63

64

65 package pet_2;

66

67 public class Mastertest {

68

69   public static void main(String[] args) {

70     Master master=new Master();

71     //Pet dog =new Dog();

72     Pet dog=Master.getPet(2);

73     master.play(dog);

74   }

75

76 }