gistfile1.java

        public HashSet<String> getSet(String key, HashSet<String> defValue) {
            String setString = this.getString(key, null);
            if (setString != null) {
                try {
                    JSONArray jsonArray = new JSONArray(setString);
                    int length = jsonArray.length();
                    HashSet<String> set = new HashSet<String>(length);
                    for (int i = 0; i < length; i++) {
                        set.add(jsonArray.getString(i));
                    }
                    return set;
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
            return defValue;
        }

        public boolean putSet(String key, HashSet<String> value) {
            return this.putString(key, new JSONArray(value).toString());
        }