creating GCM client app, asynctask fails - google-cloud-messaging

Question

While creating a GCM client application, asynctask is giving compilation errors.
OnCreate we are calling registerBackgrouod which will check whether gcm instance is running or not, if not create one.
But asyntask is giving error : "Asynctask cannot be resolved to a type"
private void registerBackground() {
new AsyncTask() {
protected String doInBackground(Void... params) {
String msg = "";
try {
if (gcm == null) {
gcm = GoogleCloudMessaging.getInstance(context);
}
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.
// For this demo: we don't need to send it because the device
// will send upstream messages to a server that echo back the message
// using the 'from' address in the message.
// Save the regid - no need to register again.
setRegistrationId(context, regid);
} catch (IOException ex) {
msg = "Error :" + ex.getMessage();
}
return msg;
}
protected void onPostExecute(String msg) {
mDisplay.append(msg + "\n");
}
}.execute(null, null, null);

Answer 1

As already observed by the AlexBcn, and according to the documentation of AsyncTask, you would pass to the AsyncTask three types as param. Because you want to return the payload of the GCM push notification as a String, you would invoke AsyncTask<Void, Void, String>
So the correct code snippet of GCM client is:
private void registerInBackground() {
new AsyncTask<Void, Void, String>() {
#Override
protected String doInBackground(Void... params) {
String msg = "";
try {
if (gcm == null) {
gcm = GoogleCloudMessaging.getInstance(context);
}
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.
// For this demo: we don't need to send it because the device will send
// upstream messages to a server that echo back the message using the
// 'from' address in the message.
// Persist the regID - no need to register again.
storeRegistrationId(context, regid);
} catch (IOException ex) {
msg = "Error :" + ex.getMessage();
// If there is an error, don't just keep trying to register.
// Require the user to click a button again, or perform
// exponential back-off.
}
return msg;
}.execute(null, null, null);
}

Answer 2

This is because of the params you pass in to Async task.
For further help:
I recently uploaded the fully functional GCM java client to my Github Account:
GCM Android Client
It has got both server and client implementation.