容器的排序-3

下面通过实例来具体使用Comparator和Comparable

public class Goods {    private String name;    private double price;    private int fav;    public Goods() {    }    public Goods(String name, double price, int fav) {        super();        this.name = name;        this.price = price;        this.fav = fav;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public double getPrice() {        return price;    }    public void setPrice(double price) {        this.price = price;    }    public int getFav() {        return fav;    }    public void setFav(int fav) {        this.fav = fav;    }    //这里需要重写Object中的toString方法，因为正常的toString方法如下：    //public String toString() {    //    return getClass().getName() + "@" + Integer.toHexString(hashCode());    //}    @Override    public String toString() {        return this.name+"--"+this.price+"--"+this.fav;    }}

import java.util.Comparator;//因为对于商品的要求不一样，有些人希望按照价格来排列，有些人希望按照人气指数来排，所以//使用Comparator的好处在于解耦，也就是同步工作，互不干扰，这里按照价格来排序，当然也//也可以按照其他的来排序public class Goodsprice implements Comparator<Goods>{    @Override    public int compare(Goods o1, Goods o2) {        //按照升序排序，前面加负号表示为降序，其实正常应该这么写：        // return -(o1.getPrice()-o2.getPrice()>0?1:(o1.getPrice()==o2.getPrice()?0:-1));        return (int) -(o1.getPrice()-o2.getPrice());    }}

import java.util.ArrayList;import java.util.Collections;import java.util.List;public class GoodsAPP {    public static void main(String[] args) {        List<Goods> list = new ArrayList<>();        list.add(new Goods("苹果", 10, 6));        list.add(new Goods("梨子", 12, 8));        list.add(new Goods("桃子", 12, 7));        list.add(new Goods("栗子", 20, 3));        list.add(new Goods("香蕉", 18, 10));        Collections.sort(list,new Goodsprice());        System.out.println(list);    }   }

输出结果为：[栗子--20.0--3, 香蕉--18.0--10, 梨子--12.0--8, 桃子--12.0--7, 苹果--10.0--6]

import java.text.DateFormatSymbols;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Date;/** * 对于新闻，按照顺序，时间降序，点击量升序，标题降序 * 使用Comparable的顺序就是已经订好的 * @author Administrator */public class NewsItem implements Comparable<NewsItem>{    private String title;    private int hit;    private String time;    public NewsItem() {    }    public NewsItem(String title, int hit,  String time) {        super();        this.title = title;        this.hit = hit;        this.time = time;    }    public String getTitle() {        return title;    }    public void setTitle(String title) {        this.title = title;    }    public int getHit() {        return hit;    }    public void setHit(int hit) {        this.hit = hit;    }    public String getTime() {        return time;    }    public void setTime(String time) {        this.time = time;    }    @Override    public int compareTo(NewsItem o) {        int result = 0;        result = -this.time.compareTo(o.time);        if(result==0){            result = this.hit-o.hit;  //因为是int类型，所以直接相减，不能使用compareTo方法            if(result==0){                result = this.title.compareTo(o.title);            }        }        return result;    }    @Override    public String toString() {        try {            return this.title+"--"+this.hit+"--"+new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(time).toLocaleString()+"\n";        } catch (ParseException e) {            e.printStackTrace();        }        return null;    }   }

import java.util.ArrayList;import java.util.Collections;import java.util.Date;import java.util.List;public class NewsApp {    public static void main(String[] args) {        List<NewsItem> list = new ArrayList<>();        list.add(new NewsItem("LPL夺冠了",1000,"2020-9-19 17:20:00"));        list.add(new NewsItem("LMS夺冠了",10,"2050-9-23 18:20:00"));        list.add(new NewsItem("LCK夺冠了",800,"2017-9-23 19:20:00"));        Collections.sort(list);        System.out.println(list);    }}

输出结果：[LMS夺冠了--10--2050-9-23 18:20:00    , LPL夺冠了--1000--2020-9-19 17:20:00    , LCK夺冠了--800--2017-9-23 19:20:00    ]