public void Save() { String numkey = "sign-amount"; String signprefix = "sign-"; // clear properties file int num = mPropertiesFile.getInt(numkey, 0); for (int i = 0; i < num; ++i) { mPropertiesFile.removeKey(signprefix + i); } // save num = mSensorList.size(); mPropertiesFile.setInt(numkey, num); for (int i = 0; i < mSensorList.size(); ++i) { mPropertiesFile.setString(signprefix + i, mSensorList.get(i).serialize()); } }