java - 无法按升序对列表进行排序

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

金额的输入值=100,500,200,10,10000

无法按金额升序对列表进行排序。它仍然按照插入的顺序显示。

我该如何解决？我很感激任何帮助。提前致谢。

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

最佳答案

假设这是您的输入

  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);

这是您的排序代码

  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

如果值为十进制，请将 return Integer.parseInt(value1)-Integer.parseInt(value2); 替换为以下代码。

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

关于java - 无法按升序对列表进行排序，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19264271/