根据List中对象的某一属性进行排序

不多说，直接看代码：

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class ListSort
{
public static void main(String[] args)
{

    class User{
        private int id;
        private String username;
        public int getId()
        {
            return id;
        }
        public void setId(int id)
        {
            this.id = id;
        }
        public String getUsername()
        {
            return username;
        }
        public void setUsername(String username)
        {
            this.username = username;
        }
    }
    List<User> list = new ArrayList<User>();
    for(int i = 1; i < 5; i++)
    {
        User user = new User();
        user.setId(i);
        user.setUsername("ldd"+i);

        list.add(user);
    }
    System.out.println("************排序前*************");
    for(int i = 0; i < list.size(); i++)
    {

        System.out.println(list.get(i).getId() + "---" + list.get(i).getUsername());
    }
    Collections.sort(list, new Comparator<User>()
                     {
                         @Override
                         public int compare(User o1, User o2)
                         {
                             return (o2.getId()) - (o1.getId());
                         }
                     });

    System.out.println("************排序后*************");
    for(int i = 0; i < list.size(); i++)
    {
        System.out.println(list.get(i).getId() + "---" + list.get(i).getUsername());
    }
}

}

结果如下：

************排序前*************
1---ldd1
2---ldd2
3---ldd3
4---ldd4
************排序后*************
4---ldd4
3---ldd3
2---ldd2
1---ldd1