Java对象排序2种实现(Comparable, Comparator)

Java里一组对象排序有2种方法:
1. 类自身实现Comparable接口;
2. 设计一个类,实现Comparator接口,作为比较器参数,传入集合工具类方法参数中
   (比如Collections.sort(List<T> list, Comparator<? super T> c)).

package test;

import java.util.*;

public class ClassCompare {
	public static void main(String[] args) {
		List<User> userList = new ArrayList<User>();
		for (int i = 0; i < 5; i++) {
			User user = new User();
			user.setId(5 - i);
			user.setName("name" + i);
			userList.add(user);
		}
		Collections.sort(userList);
		System.out.println(userList); //[1-name4, 2-name3, 3-name2, 4-name1, 5-name0]
		Collections.sort(userList, new myComparator());
		System.out.println(userList); //[5-name0, 4-name1, 3-name2, 2-name3, 1-name4]
	}
}

// 1.实现Comparable接口
class User implements Comparable<User> {
	@Override
	public String toString() {
		return id + "-" + name;
	}

	private int id;
	private String name;

	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;
	}

	@Override
	public int compareTo(User o) {
		return this.id - o.id;
	}
}

// 2.实现Comparator接口
class myComparator implements Comparator<User> {
	@Override
	public int compare(User arg0, User arg1) {
		return arg0.getName().compareTo(arg1.getName());
	}
}