title: Cannot resolve symbol
body: <p>I try to mage Google Cloud Messaging.</p>
  
  <p>I have follow class:</p>
  
  <pre><code>package de.phcom.avs;
  
  import android.content.Context;
  import android.os.AsyncTask;
  import android.widget.Toast;
  
  import com.google.android.gms.gcm.GoogleCloudMessaging;
  
  import java.io.IOException;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  public class GcmRegistrationAsyncTask extends AsyncTask&lt;Void, Void, String&gt; {
  private static Registration regService = null;
  private GoogleCloudMessaging gcm;
  private Context context;
  
  // TODO: change to your own sender ID to Google Developers Console project number, as per instructions above
  private static final String SENDER_ID = "131952017954";
  
  public GcmRegistrationAsyncTask(Context context) {
      this.context = context;
  }
  
  @Override
  protected String doInBackground(Void... params) {
      if (regService == null) {
          Registration.Builder builder = new Registration.Builder(AndroidHttp.newCompatibleTransport(),
                  new AndroidJsonFactory(), null)
                  // Need setRootUrl and setGoogleClientRequestInitializer only for local testing,
                  // otherwise they can be skipped
                  .setRootUrl("http://10.0.2.2:8080/_ah/api/")
                  .setGoogleClientRequestInitializer(new GoogleClientRequestInitializer() {
                      @Override
                      public void initialize(AbstractGoogleClientRequest&lt;?&gt; abstractGoogleClientRequest)
                              throws IOException {
                          abstractGoogleClientRequest.setDisableGZipContent(true);
                      }
                  });
          // end of optional local run code
  
          regService = builder.build();
      }
  
      String msg = "";
      try {
          if (gcm == null) {
              gcm = GoogleCloudMessaging.getInstance(context);
          }
          String regId = gcm.register(SENDER_ID);
          msg = "Device registered, registration ID=" + regId;
  
          // You should send the registration ID to your server over HTTP,
          // so it can use GCM/HTTP or CCS to send messages to your app.
          // The request to your server should be authenticated if your app
          // is using accounts.
          regService.register(regId).execute();
  
      } catch (IOException ex) {
          ex.printStackTrace();
          msg = "Error: " + ex.getMessage();
      }
      return msg;
  }
  
  @Override
  protected void onPostExecute(String msg) {
      Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
      Logger.getLogger("REGISTRATION").log(Level.INFO, msg);
  }
  }
  </code></pre>
  
  <p>and they say:</p>
  
  <ul>
  <li>Cannot resolve symbol 'Registration'</li>
  <li>Cannot resolve symbol 'AndroidHttp'</li>
  <li>Cannot resolve symbol 'AndroidJsonFactory'</li>
  </ul>
  
  <p>and so on.
  I have downloaded Google API 19 and 21.</p>