java实现List中对象的自定义排序

用户实体类:

package sort;

/**
 * 用户实体类
 */
public class User {
    
    private int id;
    private String name;
    private int age ;
    private int collect;
    
    public User(int id, String name, int age, int collect) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
        this.collect = collect;
    }
    
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    
    public int getAge() {
        return age;
    }
    
    public void setAge(int age) {
        this.age = age;
    }
    
    public int getCollect() {
        return collect;
    }
    
    public void setCollect(int collect) {
        this.collect = collect;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", age=" + age + ", collect=" + collect + "]";
    }

}

 

自定义比较器:

package sort;

import java.util.Comparator;

/**
 * 用户对象比较器, 自定义比较器, 需实现比较器接口
 */
public class UserComparator implements Comparator<User> {

    
    /**
     * 比较方法
     */
    @Override
    public int compare(User o1, User o2) {
        if(o1.getAge() > o2.getAge()) {  
            return 1;  
        }  
        else if (o1.getAge() < o2.getAge()){  
            return -1;  
        }  
        else {  
            if (o1.getCollect() >= o2.getCollect()) {
                return 1;  
            }  
            else {  
                return -1;  
            }  
        }
    }

}

 

测试类:

package sort;

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

public class Client {
    
    public static void main(String[] args) {
        User u1 =new User(1, "A", 20, 1800);
        User u2 =new User(2, "B", 21, 1750);
        User u3 =new User(3, "C", 22, 1900);
        User u4 =new User(4, "D", 21, 1700);
        User u5 =new User(5, "E", 20, 1850);

        ArrayList<User> list = new ArrayList<User>();
        list.add(u1);
        list.add(u2);
        list.add(u3);
        list.add(u4);
        list.add(u5);

        System.out.println ("排序前*******************************");
        for (User user: list){
            System.out.println (user);
        }
        
        System.out.println ("排序后*******************************");
        //把排序规则交给sort方法, 该方法会按照你自定义的规则进行排序
        Collections.sort(list, new UserComparator());//reverse反序排列
        for (User user : list){
            System.out.println (user);
        }
        
        System.out.println ("排序后*******************************");
        //匿名类方式进行排序
        Collections.sort(list, new Comparator<User>(){
            @Override
            public int compare(User o1, User o2) {
                if(o1.getAge() > o2.getAge()) {  
                    return 1;  
                }  
                else if (o1.getAge() < o2.getAge()){  
                    return -1;  
                }  
                else {  
                    if (o1.getCollect() >= o2.getCollect()) {
                        return 1;  
                    }  
                    else {  
                        return -1;  
                    }  
                }
            }});
        for (User user : list){
            System.out.println (user);
        }
    }
    
}

 

打印结果:

排序前*******************************
User [id=1, name=A, age=20, collect=1800]
User [id=2, name=B, age=21, collect=1750]
User [id=3, name=C, age=22, collect=1900]
User [id=4, name=D, age=21, collect=1700]
User [id=5, name=E, age=20, collect=1850]
排序后*******************************
User [id=1, name=A, age=20, collect=1800]
User [id=5, name=E, age=20, collect=1850]
User [id=4, name=D, age=21, collect=1700]
User [id=2, name=B, age=21, collect=1750]
User [id=3, name=C, age=22, collect=1900]
排序后*******************************
User [id=1, name=A, age=20, collect=1800]
User [id=5, name=E, age=20, collect=1850]
User [id=4, name=D, age=21, collect=1700]
User [id=2, name=B, age=21, collect=1750]
User [id=3, name=C, age=22, collect=1900]

 

 

谢谢声明出处!

转自: http://www.cnblogs.com/gscq073240/articles/7128209.html