List排序问题

来源：互联网发布：照片时间修改软件编辑：程序博客网时间：2024/05/20 11:19

对List中对象的某个字段按照从大到小或者从小到大的顺序进行排序

看代码：

首先创建一个实体对象：

package com.sort;class User {String name;String age;String birthday;public User(String name, String age, String birthday) {this.name = name;this.age = age;this.birthday = birthday;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getBirthday() {return birthday;}public void setBirthday(String birthday) {this.birthday = birthday;}}

然后组织数据，并进行排序：

package com.sort;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.Date;import java.util.List;public class SortTest {  public static void main(String[] args){  List<User> userlist=new ArrayList<User>();  userlist.add(new User("dd","4","2015-08-01"));  userlist.add(new User("aa","1","2015-08-01"));  userlist.add(new User("ee","5","2015-08-03"));  userlist.add(new User("bb","1","2015-08-04"));    userlist.add(new User("ff","5","2015-08-05"));  userlist.add(new User("cc","3","2015-08-06"));  userlist.add(new User("gg","6","2015-08-07"));   //直接调用Collections中的比较器，重写compare方法即可，不需要继承Comparable接口  Collections.sort(userlist, new Comparator<User>(){@Overridepublic int compare(User o1, User o2) {//首先比较日期大小，按照降序排列，如果要按照升序排列，只需修改成：//int flag = o1.birthday.compareTo(o2.birthday);int flag = o2.birthday.compareTo(o1.birthday);if(flag==0){//如果日期一致，则比较年龄大小按照升序排列return o1.age.compareTo(o2.age);}return flag;}    });     for (int i=0;i<userlist.size();i++){   User user_temp=(User)userlist.get(i);      System.out.println(user_temp.getAge()+","+user_temp.getName()+","+user_temp.birthday);   }   }}

运行结果

6,gg,2015-08-073,cc,2015-08-065,ff,2015-08-052,bb,2015-08-045,ee,2015-08-031,aa,2015-08-014,dd,2015-08-01

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