Android AppWidget onClick not working after garbage collection

Question

I created an AppWidget for my App and setup the updatePeriodMillis to 0, because this Widget is not doing anything, if the user does not interact.

Everything works fine, untill Android cleans the ram. Then the widget won't respond anymore until the App is started again or the device is rebooted (in both cases the onUpdate() will run again).

So my question: What do I need to do, to bring it back to work, after Android kicked out the Application?

This is part of the manifest:

    <receiver android:name="WidgetProvider" >
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            <action android:name="PATH.widgetBtnStartClicked" />
        </intent-filter>
        <meta-data android:name="android.appwidget.provider"
                   android:resource="@xml/appwidget_provider_info" />
    </receiver>

This is part of my WidgetProvider:

public class WidgetProvider extends AppWidgetProvider {

private static final String BTN_START_CLICKED = "PATH.widgetBtnStartClicked";


private static Values values;

@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
        int[] appWidgetIds) {

    super.onUpdate(context, appWidgetManager, appWidgetIds);

    // get RemoteView (widget):
    for (int i = 0; i < appWidgetIds.length; i++) {
        int appWidgetId = appWidgetIds[i];

        RemoteViews views = new RemoteViews(context.getPackageName(),
                R.layout.appwidget);


        // Register onClick for App-start-button:
        Intent intentLaunch = new Intent(BTN_APP_LAUNCH_CLICKED);
        intentLaunch.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        PendingIntent pendingIntentLaunch = PendingIntent.getBroadcast(
                context, appWidgetId, intentLaunch,
                PendingIntent.FLAG_UPDATE_CURRENT);
        views.setOnClickPendingIntent(R.id.appwidget_btn_launch,
                pendingIntentLaunch);


        appWidgetManager.updateAppWidget(appWidgetId, views);

    }

}

@Override
public void onReceive(Context context, Intent intent) {
    RemoteViews views = new RemoteViews(context.getPackageName(),
            R.layout.appwidget);

    super.onReceive(context, intent);

    AppWidgetManager appWidgetManager = AppWidgetManager
            .getInstance(context);
    ComponentName componentName = new ComponentName(context,
            WidgetProvider.class);

    if (intent.getAction().equals(BTN_APP_LAUNCH_CLICKED)) {

        //do some stuff..
    }
    // update views
    appWidgetManager.updateAppWidget(componentName, views);

}

I hope there is everything you need to understand the problem. Just tell me, if not!

Answer 1

I think your app relies only on onUpdate() to refresh the widget. There are other events that cause the pending intents to 'drop off' the widget. Such as the RAM clearing you mention.

I recommend you:
+ put your widget update code in a separate service class
+ have that class triggered when different events happen. onUpdate() and other events, example, the one that causes your RAM to be cleared.
+ ensure you update everything each time with remoteviews, because no old pending intents etc are preserved.

You can take total control over the events that trigger the widget to update.

If it suits your situation, you can also set an arbitrary alarm, using the alarmmanager and a receiver class. in this way, you can set the alarm to only be received when the phone wakes, and use that to call your update service class. in your update service class, then clear any alarm (if the update is called from another event) and set another alarm.

There are lots of questions on SO about who to use a service with widgets. It shouldnt take long to work it out. To put that info here is outside of the scope of this question.