将Map的内容按value排序

来源：互联网发布：数据分析与统计编辑：程序博客网时间：2024/05/22 13:00

首先，几个相关的类，Map、HashMap、HashTable、LinkedHashMap、TreeMap。区别：点击打开链接

其次，如何将Map类中的数据，按value排序。例子：

package sort;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

public class CollSort {
public static void main(String[] args){
   String sdf1 = new String("2015-01-11 1:01:02");
   String sdf2 = new String("2015-01-11 1:01:03");
   String sdf3 = new String("2015-01-11 1:01:12");


   Map<String, String> map = new HashMap<String, String>();
   map.put("a", sdf3);
   map.put("b", sdf1);
   map.put("c", sdf3);
   map.put("d", sdf2);


   ArrayList<Map.Entry<String, String>> infoIds =
        new ArrayList<Map.Entry<String, String>>(map.entrySet());


   //排序前
   for (int i = 0; i < infoIds.size(); i++) {
        String id = infoIds.get(i).toString();
        System.out.println(id);
   }
   //a=2015-01-11 1:01:12
   //b=2015-01-11 1:01:02
   //c=2015-01-11 1:01:12
   //d=2015-01-11 1:01:03

   System.out.println('\n');
   //排序
   Collections.sort(infoIds, new Comparator<Map.Entry<String, String>>() {
        public int compare(Map.Entry<String, String> o1, Map.Entry<String, String> o2) {
            //return (o2.getValue() - o1.getValue());
            return (o1.getValue()).compareTo(o2.getValue());
        }
   });

   //排序后
   for (int i = 0; i < infoIds.size(); i++) {
        String id = infoIds.get(i).toString();
        System.out.println(id);
   }
   //b=2015-01-11 1:01:02
   //d=2015-01-11 1:01:03
   //a=2015-01-11 1:01:12
   //c=2015-01-11 1:01:12
}
}

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