Collections.sort升序，降序写法

最新推荐文章于 2022-03-14 19:38:48 发布

原创最新推荐文章于 2022-03-14 19:38:48 发布 · 3k 阅读

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#java #开发语言 #后端

该博客展示了如何使用Java对包含时间戳的订单列表进行排序。代码示例中，自定义了Comparator来按时间升序和降序排列Order对象，时间戳由当前时间生成并带有随机延迟。通过修改Comparator的比较逻辑，可以轻松切换排序顺序。

升序

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

public class Test {
    public static void main(String[] args) throws InterruptedException {
        List<Order> list=new ArrayList<>();
        for (int i=1;i<6;i++){
            long time=System.currentTimeMillis();
            list.add(new Order(time,"name"+i));
            Thread.sleep(500);
        }

        Collections.sort(list, new Comparator<Order>() {
            @Override
            public int compare(Order o1, Order o2) {
                if (o1.getCurrentTime() - o2.getCurrentTime() == 0)
                    return 0;
                return o1.getCurrentTime() - o2.getCurrentTime() > 0 ? 1 : -1;
            }
        });
        System.out.println(list.toString());
    }


    static class Order{
       private long currentTime;
       private String name;

       Order(long currentTime,String name){
           this.currentTime=currentTime;
           this.name=name;
       }

        public long getCurrentTime() {
            return currentTime;
        }

        public void setCurrentTime(long currentTime) {
            this.currentTime = currentTime;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
        public String toString(){
           return "currentTime:"+currentTime+",name:"+name;
        }
    }


}

输入结果

[currentTime:1639535627903,name:name1, currentTime:1639535628407,name:name2, currentTime:1639535628910,name:name3, currentTime:1639535629411,name:name4, currentTime:1639535629911,name:name5]

降序

    return o1.getCurrentTime() - o2.getCurrentTime() > 0 ? -1 : 1;

输入结果

[currentTime:1639535792072,name:name5, currentTime:1639535791572,name:name4, currentTime:1639535791072,name:name3, currentTime:1639535790571,name:name2, currentTime:1639535790071,name:name1]