Java基础Day-Sixteen

应用Collection实现集合排序

package com.imooc.collection.List;
​
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
​
public class ListSorter {
​
    class SampleComparator implements Comparator<Integer>{
        //70 90 30 50
        //结果>0，则交换位置
        //结果=0或小于0，则位置不变
        @Override
        public int compare(Integer o1, Integer o2) {
            return o2-o1;//o1-o2：升序；o2-o1：降序
        }
    }
​
    public List<Integer> sort(List<Integer> list){
        Collections.sort(list,new SampleComparator());//升序排列
        System.out.println(list);
        return list;
    }
​
    public static void main(String[] args) {
        List<Integer> list=new ArrayList<>();
        list.add(70);
        list.add(90);
        list.add(30);
        list.add(50);
        System.out.println(list);
        ListSorter listSorter=new ListSorter();
        List<Integer> list1=listSorter.sort(list);
        System.out.println(list1);
    }
}

• 自定义类型如何集合排序

  package com.imooc.collection;
  ​
  public class Goods {
      private String sn;
      private String title;
  ​
      public Goods(String sn,String title){
          this.title=title;
          this.sn=sn;
      }
  ​
      @Override
      public String toString(){
          return "Goods{"+"sn='"+sn+'\''+",title='"+title+'\''+'}';
      }
  ​
      public String getSn(){
          return sn;
      }
  ​
      public String getTitle(){
          return title;
      }
  }
  ​

  package com.imooc.collection;
  ​
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  ​
  public class CustomObjectSortSample {
      private class CustomComparator implements Comparator<Goods>{
  ​
          @Override
          public int compare(Goods o1, Goods o2) {
  //            return o1.getSn().compareTo(o2.getSn());
              return o1.getTitle().compareTo(o2.getTitle());
          }
      }
  ​
      public List<Goods> sort(List<Goods> list){
          CustomComparator comp=new CustomComparator();
          Collections.sort(list,comp);
          return list;
      }
  ​
      public static void main(String[] args) {
          List<Goods> goodsList=new ArrayList<>();
          goodsList.add(new Goods("18827382190","商品A"));
          goodsList.add(new Goods("83219078978","商品B"));
          goodsList.add(new Goods("83241781237","商品C"));
          goodsList.add(new Goods("18579831426","商品D"));
          System.out.println("排序前");
          System.out.println(goodsList);
          System.out.println("排序后");
          List<Goods> list=new CustomObjectSortSample().sort(goodsList);
          System.out.println(list);
      }
  }
  ​

原文地址：https://blog.csdn.net/2301_79896868/article/details/143671403

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