Java HashMap按值和键排序 [英] Java HashMap sort by value then key
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问题描述
我试图首先按值(整数)然后按键(字符串)对HashMap进行排序。下面的方法似乎没有正确排序哈希映射。任何想法如何使它正常工作?
private static Map< String,Integer> sortHash(Map< String,Integer> map){
List< Map.Entry< String,Integer>> list = new ArrayList<>(map.entrySet());
//按整数值排序,然后按字符串键
Collections.sort(list,(a,b) - > {
int cmp1 = a.getValue() .compareTo(b.getValue());
if(cmp1!= 0)
返回cmp1;
else
返回a.getKey()。compareTo(b.getKey( ));
});
地图< String,Integer> result = new HashMap<>(); (Map.Entry< String,Integer> entry:list)
result.put(entry.getKey(),entry.getValue());
返回结果;
}
解决方案
问题在于: / p>
地图< String,Integer> result = new HashMap<>();
使用 LinkedHashMap
添加键/值对的顺序。
I am trying to sort a HashMap first by value (integer) then by key (string). The following method doesn't appear to be sorting the hashmap properly. Any ideas how to make it work properly ?
private static Map<String, Integer> sortHash(Map<String, Integer> map) {
List<Map.Entry<String, Integer>> list = new ArrayList<>(map.entrySet());
// Sort list by integer values then by string keys
Collections.sort(list, (a, b) -> {
int cmp1 = a.getValue().compareTo(b.getValue());
if (cmp1 != 0)
return cmp1;
else
return a.getKey().compareTo(b.getKey());
});
Map<String, Integer> result = new HashMap<>();
for (Map.Entry<String, Integer> entry : list)
result.put(entry.getKey(), entry.getValue());
return result;
}
解决方案
The issue is here:
Map<String, Integer> result = new HashMap<>();
Use LinkedHashMap
since this map will maintain the order of the addition of the key/value pairs.
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