java HashMap排序< String，Integer> .如何排序? [英] java HashMap sorting <String,Integer> . How to sort it?
问题描述
可能重复:
如何对地图进行排序<键，值> Java中的值?
Possible Duplicate:
How to sort a Map<Key, Value> on the values in Java?
在我的项目中，我采用了这样的HashMap
In my project, I have taken a HashMap like this
HashMap等级=新的HashMap();
假设我有:
degree.put("a",5);
degree.put("b",2);
degree.put("c",4);
degree.put("d",2);
degree.put("e",3);
degree.put("f",5);
现在我必须根据给定的Integer值对该列表进行排序
Now I have to Sort this list according to given Integer values
排序的HashMap应该是:
Sorted HashMap Should be :
{a = 5，f = 5，c = 4，e = 4，b = 4，d = 2}
我该怎么做?
推荐答案
HashMap是无序集合.它没有排序顺序.甚至TreeMap也会按键而不是值进行排序.
A HashMap is an unordered collection. It has no sort order. Even a TreeMap will sort by key, not value.
如果要按值的排序顺序准备排序列表，则必须创建一个适当的对象(例如ArrayList<Map.Entry<String,Integer>>)，遍历HashMap并插入所有条目，然后使用整理功能调用Collections.sort.
If you want to prepare a sorted list by the sort order of the values, you'll have to create an appropriate object, such as an ArrayList<Map.Entry<String,Integer>>, iterate over your HashMap and insert all the entries, and then call Collections.sort with a collation function.
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