List && Comparable

package com.testlist;
import java.util.* ;
import java.lang.Comparable ;
public class ListName {
	public static void main(String args[]) {
		List list = new ArrayList() ;
		list.add(new User("刘一",3800)) ;
		list.add(new User("赵二",2500)) ;
		list.add(new User("张四",4000)) ;
		list.add(new User("李四",5000)) ;
		list.add(new User("王五",1000)) ;
		list.add(new User("张三",4000)) ;
		list.add(new User("a四",4000)) ;
		Collections.sort(list) ;
		for(Object o: list) {
			System.out.println(o ) ;
		}
	}

}
class User implements Comparable {
	private String name ;
	private int salary  ;
	User(){}
	public User(String name, int salary) {
		this.name = name ;
		this.salary = salary ;
	}
	public int compareTo(Object obj) {
//		if (obj instanceof User) { //仅按钱数比较
//			User user = (User) obj;
//			return user.salary - this.salary;
//		} else
//			return -1 ;
		
		//当钱数相等时 ，按姓名比较
		User user = (User) obj ;
		int result = user.salary-this.salary ;
		return (result != 0 ? result: name.compareTo(user.name)) ;
	}
	public String toString() {
		return name + "   " + salary ;
	}
}

console:
 李四   5000
a四   4000
张三   4000
张四   4000
刘一   3800
赵二   2500
王五   1000