项目实例A

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

public class Users implements Comparable<Users>{
    
	private String name;
	private int amount;
	
	public Users(String name, int amount) {
		this.name = name;
		this.amount = amount;
	}
	
	public int compareTo(Users user) {
		return 0;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAmount() {
		return amount;
	}
	//测试方法
	public static void main(String [] args) {
		List<Users> list = new ArrayList<Users>();
		list.add(new Users("巴塞", 2700));
		list.add(new Users("皇马", 2100));
		list.add(new Users("罗马", 2400));
		list.add(new Users("曼联", 2300));
		list.add(new Users("米兰", 2600));
		for (Users user : list) {
			System.out.println(user.getName()+" => "+user.getAmount());
		}
		System.out.println("===========");
		Collections.sort(list, new Comparator<Users>(){
			public int compare(Users ua, Users ub) {
				System.out.println(ub.getAmount()- ua.getAmount());
				return ub.getAmount()- ua.getAmount();
			}		
		});
		System.out.println("===========");
		for (Users user : list) {
			System.out.println(user.getName()+" => "+user.getAmount());
		}
	}
}

控制台结果      （集合按数排序）

巴塞 => 2700
皇马 => 2100
罗马 => 2400
曼联 => 2300
米兰 => 2600
===========
-600
300
-300
200
-100
500
300
200
-100
===========
巴塞 => 2700
米兰 => 2600
罗马 => 2400
曼联 => 2300
皇马 => 2100