Check if Play Services are installed for the GPS Tutorial on the SSaurel's Blog

checkPlayServices.java

private boolean checkPlayServices() {
	GoogleApiAvailability apiAvailability = GoogleApiAvailability.getInstance();
	int resultCode = apiAvailability.isGooglePlayServicesAvailable(this);

	if (resultCode != ConnectionResult.SUCCESS) {
		if (apiAvailability.isUserResolvableError(resultCode)) {
			apiAvailability.getErrorDialog(this, resultCode, PLAY_SERVICES_RESOLUTION_REQUEST);
		} else {
			finish();
		}

		return false;
	}

	return true;
}