Java实体类对象的排序

1. 通过在实体类中实现compartable中的compareTo方法

package com.lifeng.collection.sort.innerType;

import java.util.Date;

/**
 * 新闻实体类
 * @author 51093
 * @param <T>
 *
 */
public class NewsItem implements Comparable<NewsItem>{
	
	private String title;//标题
	private int hits;//点击量
	private Date pubTime;//时间
	
	public NewsItem() {
		super();
		
	}


	public NewsItem(String title, int hits, Date pubTime) {
		super();
		this.title = title;
		this.hits = hits;
		this.pubTime = pubTime;
	}


	public String getTitle() {
		return title;
	}
	public void setTitle(String title) {
		this.title = title;
	}
	public int getHits() {
		return hits;
	}
	public void setHits(int hits) {
		this.hits = hits;
	}
	public Date getPubTime() {
		return pubTime;
	}
	public void setPubTime(Date pubTime) {
		this.pubTime = pubTime;
	}
	//先按时间降序，点击量升序，标题排序降序
	@Override
	public int compareTo(NewsItem o) {
		int result=0;
		result=-this.pubTime.compareTo(o.getPubTime());//降序
		if(0==result) {
			//时间相同则按照点击量排序
			result=this.hits-o.getHits();
			if(0==result) {
				//相同则按照标题降序
				result=-this.title.compareTo(o.getTitle());
			}
		}
		return result;
	}
	
	@Override
	public String toString() {
		StringBuffer sb=new StringBuffer();
		sb.append("标题是："+this.title+",");
		sb.append("时间是："+this.pubTime+",");
		sb.append("点击量是："+this.hits+"\n");
		
		return sb.toString();
	}
}

package com.lifeng.collection.sort.innerType;

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

public class NewsItemApp {
	public static void main(String[] args) {
		List<NewsItem> list=new ArrayList<>();
		list.add(new NewsItem("东方饭店深V",1000,new Date()));
		list.add(new NewsItem("对方水电费",100,new Date()));
		list.add(new NewsItem("的范德萨发放",89,new Date(System.currentTimeMillis()-1000*60*60)));
		System.out.println("排序前:"+list);
		//排序
		list.sort(null);
		System.out.println("排序之后：");
		System.out.println("排序之后："+list);
		
		System.out.println("实体类对象："+new NewsItem("东方饭店深V",1000,new Date()));
	}
}

2、通过实现compartor中的自定义排序规则

package com.lifeng.collection.sort.innerType;

/**
 * 商品实体类
 * @author 51093
 *
 */
public class Goods {
	private String name;//商品名称
	private int fav;//收藏量
	private int price;//价格
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getFav() {
		return fav;
	}
	public void setFav(int fav) {
		this.fav = fav;
	}
	public int getPrice() {
		return price;
	}
	public void setPrice(int price) {
		this.price = price;
	}
	public Goods() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Goods(String name, int fav, int price) {
		super();
		this.name = name;
		this.fav = fav;
		this.price = price;
	}
	
	@Override
	public String toString() {
		StringBuffer sb=new StringBuffer();
		sb.append("商品名称："+this.name+",");
		sb.append("收藏量："+this.fav+",");
		sb.append("商品价格："+this.price+"\n");
		
		return sb.toString();
	}
}

package com.lifeng.collection.sort.innerType;

import java.util.Comparator;

public class GoodsPriceComp implements Comparator<Goods>{

	@Override
	public int compare(Goods o1, Goods o2) {
		
		return -(o1.getPrice()-o2.getPrice()>0?1:(o1.getPrice()-o2.getPrice()==0?0:-1));
	}

}

package com.lifeng.collection.sort.innerType;

import java.util.ArrayList;
import java.util.List;

public class GoodsApp {
	public static void main(String[] args) {
		List<Goods> list=new ArrayList<>();
		list.add(new Goods("佛挡杀佛",100,100));
		list.add(new Goods("辅导费",103,10));
		list.add(new Goods("辅导风",105,80));
		list.add(new Goods("如果",106,900));
		System.out.println("排序之前："+list);
		//排序
		list.sort(new GoodsPriceComp());
		System.out.println("排序之后："+list);
	}
}

 

转载于:https://my.oschina.net/u/3901218/blog/1930409