I’ve been studying from the book “Pro Android 2.” I’m working through a Service example that consists of two classes: BackgroundService.java and MainActivity.java. The MainActivity claims (erroneously?) it starts the Service as indicated by output to logcat from the Log.d call below:
public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d(TAG, "starting service");
Button bindBtn = (Button)findViewById(R.id.bindBtn);
bindBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
Intent backgroundService = new Intent(MainActivity.this, com.marie.mainactivity.BackgroundService.class);
startService(backgroundService);
}
});
Button unbindBtn = (Button)findViewById(R.id.unbindBtn);
unbindBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
stopService(new Intent(MainActivity.this, BackgroundService.class));
}
});
}
}
What puzzles me is the UI provides two buttons: Bind and UnBind as shown above. But according to the documentation if onBind() as shown below returns null that indicates you don’t want to allow binding. But as shown above the onClick() method of (the Bind button) bindBtn.setOnClickListener(new OnClickListener() calls startService(backgroundService) which gives this error:”Unable to start service Intent { cmp=com.marie.mainactivity/.BackgroundService }: not found”
public class BackgroundService extends Service {
private NotificationManager notificationMgr;
@Override
public void onCreate() {
super.onCreate();
notificationMgr = NotificationManager)getSystemService(NOTIFICATION_SERVICE);
displayNotificationMessage("starting Background Service");
Thread thr = new Thread(null, new ServiceWorker(), "BackgroundService");
thr.start();
}
class ServiceWorker implements Runnable
{
public void run() {
// do background processing here...
//stop the service when done...
//BackgroundService.this.stopSelf();
}
}
@Override
public void onDestroy()
{
displayNotificationMessage("stopping Background Service");
super.onDestroy();
}
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
private void displayNotificationMessage(String message)
{
Notification notification = new Notification(R.drawable.note, message, System.currentTimeMillis());
PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);
notification.setLatestEventInfo(this, "Background Service", message, contentIntent);
notificationMgr.notify(R.id.app_notification_id, notification);
}
}
I don’t understand the point of this example. If onBind() returns null what’s the point of having a Bind button (bindBtn)? I thought the point was to show how to start a BackgroundService. But it doesn’t seem to work unless I’m missing something.
I should add I have added to my AndroidManifest.xml:
<service android:name=".BackgroundService"></service>
as follows:
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<service android:name=".BackgroundService"></service>
</activity>
</application>
Remove the service from inside the activity. It is at the same level as the activity within the application. Eg: