1.Main
package s0223多条件排序;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;
public class Main {
public static void main
(String[] args
) { List<NewsItem> news=new ArrayList<NewsItem>();
news.
add(new NewsItem
("中国登上钓鱼岛",
100,
new Date(System.
currentTimeMillis() ) ) ); news.
add(new NewsItem
("中国GDP总量",
40,
new Date(System.
currentTimeMillis() ) ) ); news.
add(new NewsItem
("美国总统与xx会晤",
60,
new Date(System.
currentTimeMillis() ) ) );
System.
out.
println("排序前:"+news
); //因为news中的元素都是Comparable的实现类的实例,所以默认使用指定的Comparator
//如果使用comparator的实现类,那么要指定comparator
System.
out.
println("排序后:"+news
);
}
}
2.NewsItem类,在这个类中定义了排序优先级和排序顺序
package s0223多条件排序;
import java.text.SimpleDateFormat;
//新闻按时间降序,点击量升序,标题降序
import java.util.Date;
public class NewsItem implements java.lang.Comparable<NewsItem>{
private int hit;
public NewsItem(){}
public NewsItem
(String title,
int hit,
Date pubTime
) {
super();
this.title = title;
this.hit = hit;
this.pubTime = pubTime;
}
//新闻按时间降序,点击量升序,标题降序,3个if嵌套,规定了排序的优先级
public int compareTo(NewsItem o)
{
int result=0;
result=-this.pubTime.compareTo(o.pubTime);//加了- 变成降序
if(result==0)
{
result=this.hit-o.hit;
if(result==0)
{
result=this.title.compareTo(o.title);
}
}
return result;
}
{
StringBuilder sb=new StringBuilder();
sb.append(" 标题:").append(this.title);
sb.
append(" 时间:").
append(new SimpleDateFormat("yyyy-MM-dd").
format(this.
pubTime)); sb.append(" 点击量:").append(this.hit).append("\n");
return str;
}
return title;
}
public void setTitle
(String title
) { this.title = title;
}
public int getHit() {
return hit;
}
public void setHit(int hit) {
this.hit = hit;
}
public Date getPubTime
() { return pubTime;
}
public void setPubTime
(Date pubTime
) { this.pubTime = pubTime;
}
}