Problems in Calling AsyncTask from IntentService

Issue

I have created IntentService class and performing asyncTask but getting exception when onPreExecute() is called at this code line pDialog.show();

AsyncHandlerService Class ---

public class AsyncHandlerService extends IntentService{
ProgressDialog pDialog;
HttpPost post;
HttpResponse response;
Context ctx;

public AsyncHandlerService() {
    super("AsyncHandlerService");
    ctx = this;
}

@Override
protected void onHandleIntent(Intent intent) {
    new LoadDeviceInfo().execute();   
}


class LoadDeviceInfo extends AsyncTask<String, String, String> {

@Override
protected void onPreExecute() {
    super.onPreExecute();
    pDialog = new ProgressDialog(ctx);
    pDialog.setMessage("Updating device info...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show(); //Exception here..
}

protected String doInBackground(String... args) {
}

protected void onPostExecute(String file_url) {
    pDialog.dismiss();
}

UPDATE:

I am calling the IntentService in the broadcast receiver that has the intent filter of android.intent.action.PACKAGE_REPLACED defined in android manifest. The code ---

public class OnUpgradeBroadcastReceiver extends BroadcastReceiver {
Context activity;
@Override
    public void onReceive(final Context context, final Intent intent) {
         activity = context;
         Intent msgIntent = new Intent(activity, AsyncHandlerService.class);
            activity.startService(msgIntent);
    }
}

Error Log:

com.testapp.main fatal error : Unable to add window -- 
token null is not for an application
android.view.WindowManager$BadTokenException: Unable to add window -- 
token null is not for an application
at android.view.ViewRootImpl.setView(ViewRootImpl.java:588)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:326)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
at android.view.WindowManagerImpl$CompatModeWrapper.
addView(WindowManagerImpl.java:149)
at android.app.Dialog.show(Dialog.java:277)
at com.testapp.main.AsyncHandlerService$LoadDeviceInfo.
onPreExecute(AsyncHandlerService.java:62)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)

Solution

First, IntentService already uses a background thread. You do not need another background thread. Do the work that needs to be done in the background in onHandleIntent().

Second, a Service cannot display a Dialog. Instead, let the UI layer of your app know that the work was done via a message on an event bus (e.g., LocalBroadcastManager, greenrobot's EventBus, Square's Otto). If the UI layer does not handle the event, your service can raise a Notification or otherwise let the user know about the work that was done, if that is needed.

Answered By - CommonsWare