java - 如何让Hashmap有序？

Question

除了使用 LinkeHashmap 之外，我还可以得到一个键有序的 Hashmap 吗？

        Map<String,String> myMapTmp = XXDao().getXXX();
        Map<String,String> myMap = new LinkedHashMap<String,String>();

        List<String> keyList = new ArrayList<String>();
        Iterator<String> it =myMapTmp.keySet().iterator();
        while(it.hasNext()){
            keyList.add(it.next());
        }
        Collections.sort(keyList);
        Iterator<String> it2 = keyList.iterator();
        while(it2.hasNext()){
            String key = it2.next();
            myMap.put(key, myMapTmp.get(key));
        } 

Answer 1

您可以将 TreeMap 与 HashMap 的映射一起使用

Map<String,String> myMapTmp = XXDao().getXXX();
// TreeMap keeps all entries in sorted order
TreeMap<String, String> sortedMap = new TreeMap<>(myMapTmp);
Set<Entry<String, String>> mappings = sortedMap.entrySet(); 
System.out.println("HashMap after sorting by keys in ascending order "); 
for(Entry<String, String> mapping : mappings){ 
   System.out.println(mapping.getKey() + " ==> " + mapping.getValue()); 
}