java double list排序 java list如何排序

调用java.util.Collections.sort(List list)方法来进行排序的时候，List内的Object都必须实现了Comparable接口，否则会报ClassCastException错。

或用java.util.Collections.sort(List list，Comparator c)，临时声明一个Comparator来实现排序

package com.my.util;

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

/**
 * 使用Comparator对List排序
 */
public class ListSort {

	static List<Person> personList = new ArrayList<Person>();
	
	public static void initList() {
		personList.add(new Person("a",15,"123"));
		personList.add(new Person("c",16,"123"));
		personList.add(new Person("j",17,"123"));
		personList.add(new Person("d",21,"123"));
		personList.add(new Person("b",18,"123"));
	}

	public static void main(String[] args) {
		initList();
		for (int i = 0; i < personList.size(); i++) {
			System.out.println(personList.get(i));
		}
		System.out.println("======================================");
		
		//默认排序，
		Collections.sort(personList);
		for (int i = 0; i < personList.size(); i++) {
			System.out.println(personList.get(i));
		}
		
		System.out.println("======================================");
		
		//实现接口Comparator自定义排序
		Collections.sort(personList,new Comparator<Person>() {
			//按年龄排序
			@Override
			public int compare(Person o1, Person o2) {
				int flag = 0;
				if (o1.getAge()>o2.getAge()) {
					flag = 1;
				} else if (o1.getAge()<o2.getAge()) {
					flag = -1;
				}
				return flag;
			}
			
		});
		for (int i = 0; i < personList.size(); i++) {
			System.out.println(personList.get(i));
		}
	}
}

class Person implements Comparable<Person> {
	private String name;
	private int age;
	private String cardid;
	
	public Person() {
		
	}
	public Person(String name, int age, String cardid) {
		this.name = name;
		this.age = age;
		this.cardid = cardid;
	}

	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 String getCardid() {
		return cardid;
	}

	public void setCardid(String cardid) {
		this.cardid = cardid;
	}
	
	public String toString() {
		return this.name+","+this.age+","+this.cardid;
	}
	
	public int compareTo(Person p) {
		// TODO Auto-generated method stub
		return this.name.compareTo(p.getName());
	}
}