Question

I have Datastore Class and I use this class to try GCM . I do not understand where the data is saved (registrations id) but I can retrive this after I restart my IDE (Eclipse)

Thanks friends

private static final DatastoreService datastore =
    DatastoreServiceFactory.getDatastoreService();

private Datastore() {
  throw new UnsupportedOperationException();
}

/**
 * Registers a device.
 *
 * @param regId device's registration id.
 */

public static void register(String regId) {
  logger.info("Registering " + regId);
  Transaction txn = datastore.beginTransaction();
  try {
    Entity entity = findDeviceByRegId(regId);
    if (entity != null) {
      logger.fine(regId + " is already registered; ignoring.");
      return;
    }
    entity = new Entity(DEVICE_TYPE);
    entity.setProperty(DEVICE_REG_ID_PROPERTY, regId);
    datastore.put(entity);
    txn.commit();
    } finally {
    if (txn.isActive()) {
      txn.rollback();
    }
  }
}

/**
 * Gets all registered devices.
 */

public static List<String> getDevices() {
  List<String> devices;
  Transaction txn = datastore.beginTransaction();
  try {
    Query query = new Query(DEVICE_TYPE);
    Iterable<Entity> entities =
        datastore.prepare(query).asIterable(DEFAULT_FETCH_OPTIONS);
    devices = new ArrayList<String>();
    for (Entity entity : entities) {
      String device = (String) entity.getProperty(DEVICE_REG_ID_PROPERTY);
      devices.add(device);
    }
    txn.commit();
  } finally {
    if (txn.isActive()) {
      txn.rollback();
    }
  }
  return devices;
}

Answer 1

The data is stored either in GAE datastore when you are in production servers, or in a local file when you are in local development environment ( https://appengine.google.com/ –> application –>Datastore Indexes).
In any case, you can see what data is stored in your app from admin console. For the development environment, you can check at

localhost:8888/_ah/admin (from your browser)