Java中Comparable和Comparator实现对象比较

 1 import java.util.Arrays;
 2 public class ComparableUser implements Comparable {
 3 
 4     private String id;
 5     private int age;
 6 
 7     public ComparableUser(String id, int age) {
 8         this.id = id;
 9         this.age = age;
10     }
11 
12     public int getAge() {
13         return age;
14     }
15 
16     public void setAge(int age) {
17         this.age = age;
18     }
19 
20     public String getId() {
21         return id;
22     }
23 
24     public void setId(String id) {
25         this.id = id;
26     }
27 
28     public int compareTo(Object o) {
29         return this.age - ((ComparableUser) o).getAge();
30     }
31 
32     /**
33      * 测试方法
34      */
35     public static void main(String[] args) {
36         ComparableUser[] users = new ComparableUser[] {
37                 new ComparableUser("u1001", 25),
38                 new ComparableUser("u1002", 20),
39                 new ComparableUser("u1003", 21) };
40         Arrays.sort(users);
41         for (int i = 0; i < users.length; i++) {
42             ComparableUser user = users[i];
43             System.out.println(user.getId() + " " + user.getAge());
44         }
45     }
46 
47 }

 1 public class User {
 2 
 3     private String id;
 4     private int age;
 5 
 6     public User(String id, int age) {
 7         this.id = id;
 8         this.age = age;
 9     }
10 
11     public int getAge() {
12         return age;
13     }
14 
15     public void setAge(int age) {
16         this.age = age;
17     }
18 
19     public String getId() {
20         return id;
21     }
22 
23     public void setId(String id) {
24         this.id = id;
25     }
26     
27 
28 }

 1 import java.util.Arrays;
 2 import java.util.Comparator;
 3 public class UserComparator implements Comparator {
 4 
 5     public int compare(Object arg0, Object arg1) {
 6         return ((User) arg0).getAge() - ((User) arg1).getAge();
 7     }
 8 
 9     /**
10      * 测试方法
11      */
12     public static void main(String[] args) {
13         User[] users = new User[] { new User("u1001", 25),
14                 new User("u1002", 20), new User("u1003", 21) };
15         Arrays.sort(users, new UserComparator());
16         for (int i = 0; i < users.length; i++) {
17             User user = users[i];
18             System.out.println(user.getId() + " " + user.getAge());
19         }
20     }
21 }