java中Hashmap按key排序

在实际的工作中，有时会有Hashmap按key排序 的需求，我找的方法如下：

一、

              <pre name="code" class="java"> HashMap<String, List<Integer>> raceMap = new HashMap<String, List<Integer>>(); Object[] key_arrrObjects = raceMap.keySet().toArray();Arrays.sort(key_arrrObjects);for  (Object key : key_arrrObjects) {       Object value = raceMap.get(key);       System.out.println(value.toString());}

二、

Set<String> set =raceMap.keySet();ArrayList<String> arrayList =new ArrayList<String>(set);Collections.sort(arrayList);//从小到大的排序for (int len = arrayList.size(),i = len-1; i >= 0; i--) { System.out.println("key键---值: "+arrayList.get(i)+","+raceMap.get(arrayList.get(i)));}