public static void main(String[] args) {
    final String str = "{\"45\":[119],\"44\":[119,118,117]}";
    final Map<Integer,List<Integer>> label2Ids =  new HashMap<Integer,List<Integer>>();
    JSONObject labelObj = new JSONObject(str);
    if (labelObj != null) {
        Iterator<String> it = labelObj.keys();
        while (it.hasNext()) {   
            List<Integer> baseIdList = new ArrayList<Integer>();
            final String key  = (String) it.next();
            JSONArray baseIds = labelObj.getJSONArray(key);
             //第一個輸出
            System.out.println("key = " + key + ",baseIds = " + baseIds);
             final int baseIdCnt = ((baseIds != null) ? baseIds.length() : 0);
             if (baseIdCnt > 0) {
                 for (int i = 0; i < baseIdCnt; i ++) {
                     baseIdList.add(baseIds.getInt(i));
                  }
              }
              label2Ids.put(Integer.parseInt(key), baseIdList);
        }
        //第二個輸出
        System.out.println("label2Ids = " + label2Ids.toString());
    }
}

列印結果如下:
key = 44,baseIds = [119,118,117]
key = 45,baseIds = [119]
label2Ids = {44=[119, 118, 117], 45=[119]}