java,对象排序

Java对象排序有两种方法

一，在对象类中实现接口 comparable

package com.m01.collections;

public class User implements Comparable {
    private int id;
    private String name;
    private double score;
    public User() {
        super();
    }
    public User(int id, String name, double score) {
        super();
        this.id = id;
        this.name = name;
        this.score = score;
    }

    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 double getScore() {
        return score;
    }
    public void setScore(double score) {
        this.score = score;
    }
    @Override
    public int compareTo(Object o) {
        User user=(User) o;
        if(this.score>user.score){
            return 1;
        }
        else if(this.score<user.score){
            return -1;
        }else{
            if(this.id>user.id){
                return 1;
            }
            else if(this.id<user.id){
                return -1;
            }else{
                return 0;
            }
        }
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", score=" + score + "]";
    }

}

List<User> list=new ArrayList();
        list.add(new User(1, "夏末", 12));
        list.add(new User(2, "夏末2", 12));
        list.add(new User(2, "夏末", 13));
        list.add(new User(4, "夏末", 12));
        list.add(new User(0, "夏末", 12));
        Collections.sort(list);
        for(User user : list){
            System.out.println(user);
        }

二，编写比较器 实现comparator,对象类不需要实现comparable接口

List<Person> listp=new ArrayList();
        listp.add(new Person(1, "夏末", 1));
        listp.add(new Person(3, "夏末", 102));
        listp.add(new Person(2, "夏末", 120));
        listp.add(new Person(4, "夏末", 2));
        listp.add(new Person(0, "夏末", 0));
        Collections.sort(listp,new Comparator<Person>() {
            @Override
            public int compare(Person o1, Person o2) {
                if(o1.getScore()>o2.getScore()){
                    return 1;
                }else if(o1.getScore()<o2.getScore()){
                    return -1;
                }else{
                    return 0;
                }
            }
        });
        for(Person user:listp){
            System.out.println(user.toString());
        }