无法按升序对列表进行排序 [英] Unable to sort the list by ascending order

问题描述

Map<String, String> map ;
List<Map<String, String>> list = new ArrayList<Map<String, String>>();


/////OnCreate.............


function1(){
map = new TreeMap<String, String>();
map.put("id", "id");
map.put("amont", "amount");

list.add(map);

System.out.println(list);
}

id = 1,3,5,57,80的输入值

input values for id=1,3,5,57,80

金额的输入值= 100,500,200,10,10000

input values for amount=100,500,200,10,10000

无法按金额的升序对列表进行排序。它仍按插入顺序显示。

Unable to sort the list by ascending order of amount. It still shows in the order it was inserted.

我该如何解决这个问题？我感谢任何帮助。在此先感谢。

How do I fix this? I appreciate any help. Thanks in advance.

预期输出：金额升序：

amt=10 id=4  
amt=100 id=1  
amt=200 id=3  
amt=500 id=2  
amt=10000 id=5  

推荐答案

假设这是你的输入

  Map<String, String> map ;
  List<Map<String, String>> list = new ArrayList<Map<String, String>>();
  map = new TreeMap<String, String>();
  map.put("id","1");
  map.put("amount","100");
  list.add(map);
  map = new TreeMap<String, String>();
  map.put("id","2");
  map.put("amount","500");  
  list.add(map);
  map = new TreeMap<String, String>();
  map.put("id","3");
  map.put("amount","200");
  list.add(map);
  map = new TreeMap<String, String>();
  map.put("id","4");
  map.put("amount","10");
  list.add(map);
  map = new TreeMap<String, String>();
  map.put("id","5");
  map.put("amount","10000");
  list.add(map);

这是您的分拣代码

  Collections.sort(list, new Comparator<Map<String, String>>() {

        @Override
        public int compare(Map<String, String> o1, Map<String, String> o2) {
            String value1 =  o1.get("amount");
            String value2 =  o2.get("amount");
            return Integer.parseInt(value1)-Integer.parseInt(value2);
        }
    });

    for (Map<String, String> map1 : list) {
        String id = map1.get("id");
        String amount = map1.get("amount");
        System.out.println("amount= "+amount + " , " +"id = "+id);
    }

输出

amount= 10 , id = 4
amount= 100 , id = 1
amount= 200 , id = 3
amount= 500 , id = 2
amount= 10000 , id = 5

更新

替换返回Integer.parseInt（value1）-Integer.parseInt（value2）; 如果值为十进制，则代码如下。

Replace return Integer.parseInt(value1)-Integer.parseInt(value2); with the following code if the values are decimal.

return Double.valueOf(value1).compareTo(Double.valueOf(value2));

这篇关于无法按升序对列表进行排序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！