Collections.sort()自定义排序针对字符串集合和 list对象排序

野性酷女 2022-05-26 03:50 422阅读 0赞

字符串集合的自定义排序：

package ceshi;

import java.util.Arrays;  
import java.util.Collections;  
import java.util.Comparator;  
import java.util.List;  
  
  
public class ceshi \{  
public static void main(String\[\] args)\{  
String\[\] monthDays = "1,2,4,5,7,8,56,11,30,21,23,26,27,4,98".split(",");  
List<String> yearListlist = Arrays.asList(monthDays);  
Collections.sort(yearListlist,new SComparator());  
for(String kk :yearListlist)\{  
System.out.println(kk);  
\}  
  
\}  
  
  
      
    static class SComparator implements Comparator \{    
        public int compare(Object object1, Object object2) \{// 实现接口中的方法    
            Integer p1 = Integer.parseInt(String.valueOf(object1)); // 强制转换    
            Integer p2 = Integer.parseInt(String.valueOf(object2));  
            if(p1 > p2)\{  
            return 1;  
            \}else if(p1 == p2)\{  
            return 0;  
            \}else\{  
            return -1;  
            \}  
            //return new Double(p1.price).compareTo(new Double(p2.price));    
            //return p1.compareTo(p2);  
        \}    
    \}

list对象排序自定义排序，对象实现Comparable接口 ，重写compareTo()方法来实现：

package test;  
  
public class Pojo implements Comparable\{  
private Integer bijiao;  
private String nameString;  
private String status;  
public Integer getBijiao() \{  
return bijiao;  
\}  
public void setBijiao(Integer bijiao) \{  
this.bijiao = bijiao;  
\}  
public String getNameString() \{  
return nameString;  
\}  
public void setNameString(String nameString) \{  
this.nameString = nameString;  
\}  
public String getStatus() \{  
return status;  
\}  
public void setStatus(String status) \{  
this.status = status;  
\}  
  
@Override  
public int compareTo(Object gg)\{  
Pojo kk = (Pojo)gg;  
if(this.bijiao>kk.bijiao)\{  
return 1;  
\}else \{  
return -1;  
\}  
\}  
\}

package test;  
  
  
import java.util.ArrayList;  
import java.util.Collections;  
import java.util.List;  
  
  
public class bi \{  
public static void main(String\[\] args)\{  
List<Pojo> ceshi = new ArrayList<Pojo>();  
Pojo k1 = new Pojo();  
k1.setBijiao(1);  
k1.setNameString("k1");  
  
Pojo k2 = new Pojo();  
k2.setBijiao(2);  
k2.setNameString("k2");  
  
Pojo k3 = new Pojo();  
k3.setBijiao(3);  
k3.setNameString("k3");  
  
ceshi.add(k3);  
ceshi.add(k2);  
ceshi.add(k1);  
Collections.sort(ceshi);  
  
for(Pojo zz:ceshi)\{  
System.out.println(zz.getNameString());  
\}  
\}

compareto就是比较两个数据的大小关系 大于0表示前一个数据比后一个数据大， 0表示相等，小于0表示第一个数据小于第二个数据.

# [升序 Collections.sort(list) 降序 Collections.reserve(list) 随机 Collections.shuffle(list)][Collections.sort_list_ _ Collections.reserve_list_ _ Collections.shuffle_list] #

[Collections.sort_list_ _ Collections.reserve_list_ _ Collections.shuffle_list]: https://www.cnblogs.com/1020182600HENG/p/5917462.html