1 package com.app;
 2
 3 import java.util.ArrayList;
 4 import java.util.Collections;
 5 import java.util.Comparator;
 6 import java.util.List;
 7
 8 public class A1 {
 9
10     public static void main(String[] args) {
11         List<Person> list = getData() ;
12         //排序
13         Collections.sort( list , comparator );
14
15         for (Person person : list) {
16             System.out.println("person   " + person.getName() + "  " + person.getAge() );
17         }
18
19     }
20
21     /**
22      * 年龄按从小到大排序
23      */
24     static Comparator<Person> comparator = new Comparator<Person>() {
25         @Override
26         public int compare(Person p1 , Person p2 ) {
27             if( p1.getAge() > p2.getAge() ){
28               return 1 ;  //正数
29             }else if ( p1.getAge() < p2.getAge()) {
30                 return -1 ;  //负数
31             }else {
32                 return 0;  //相等为0
33             }
34         }
35     };
36
37     static private List<Person> getData() {
38         List<Person> list = new ArrayList<>() ;
39
40         Person p1 = new Person() ;
41         p1.setAge( 10 );
42         p1.setName( "p1" );
43
44         Person p2 = new Person() ;
45         p2.setAge( 30 );
46         p2.setName( "p2" );
47
48         Person p3 = new Person() ;
49         p3.setAge( 20 );
50         p3.setName( "p3" );
51
52         Person p4 = new Person() ;
53         p4.setAge( 15 );
54         p4.setName( "p4" );
55
56         list.add( p1 ) ;
57         list.add( p2 ) ;
58         list.add( p3 ) ;
59         list.add( p4 ) ;
60
61         return list ;
62     }
63 }

package com.app;public class Person {private int age ;private String name ;public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}