Android widget not responding to touches

Question

I'm trying just some very simple code to get an Android widget going but with no luck. I've looked around everywhere and haven't found a good answer.

All I want (for now) is to increment a counter when the widget is touched and display the current value.

This is my AppWidgetProvider:

public class WordWidget extends AppWidgetProvider
{
    Integer touchCounter = 0;

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
    {
        //This is run when a new widget is added or when the update period expires.
        Log.v("wotd",  "Updating " + appWidgetIds.length + " widgets");

        for(int x = 0; x < appWidgetIds.length; x++)
        {
            Integer thisWidgetId = appWidgetIds[x];

            RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widgetlayout);
            remoteViews.setTextViewText(R.id.mainText, touchCounter.toString());

            Intent widgetIntent = new Intent(context, WordWidget.class);
            widgetIntent.setAction("UPDATE_NUMBER");

            PendingIntent widgetPendingIntent = PendingIntent.getBroadcast(context, 0, widgetIntent, 0);

            remoteViews.setOnClickPendingIntent(R.id.widgetLinearLayout, widgetPendingIntent);
            appWidgetManager.updateAppWidget(thisWidgetId, remoteViews);
        }
    }

    @Override
    public void onReceive(Context context, Intent intent)
    {
        Log.v("wotd", "In onReceive with intent=" + intent.toString());
        if (intent.getAction().equals("UPDATE_NUMBER"))
        {
            Log.v("wotd", "In UPDATE_NUMBER");
            touchCounter++;
            RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widgetlayout);
            remoteViews.setTextViewText(R.id.mainText, touchCounter.toString());
        } else
        {
            Log.v("wotd", "In ELSE... going on to super.onReceive()");
            super.onReceive(context, intent);
        }
    }
}

This is part of my manifest:

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >

    <receiver
        android:icon="@drawable/ic_launcher"
        android:name="com.example.mywidget.WordWidget"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            <action android:name="UPDATE_NUMBER" />
        </intent-filter>

        <meta-data
            android:name="android.appwidget.provider"
            android:resource="@xml/widgetinfo" />
    </receiver>

</application>

The log shows the onReceive() is called immediately after being placed on the home screen, and after being touched, however the number never increases. I don't totally understand how widgets work, but are they killed after onUpdate()? So to do this I would have to use some kind of persistant storage?

Also, if I currently add another widget both would show the same values and increment even if I just touch one. Is there a way for each and any widget to have it's own counter?

Thanks!

score 13 · Accepted Answer · answered May 13 '12 at 15:48

Actually you have answered your question. But let's clarify some things:

A. AppWidgets are NOT killed as long as they are on a home screen. But they don't belong to you. They are running in the process of the home application. To be more specific their views are running in the process of the home application, this is why you are see your widget but it doesn't do what you are expected and this is why we are using RemoteViews instead of Views in order to update them.

B. AppWidgetProviders (in your case the WordWidget class), on the other hand, are destroyed as soon as the onReceive method finishes. All the variables in them are re-initialized every time the onReceive method gets called. This is why your number never increases. The purpose of an AppWidgetProvider is to update the widget's RemoteViews and to inform your application that a registered broadcast has arrived.

C. AppWidgetProvider's onUpdate method provides you an Array with the widgets Ids that must be updated. This is the only code point you can use to get the number of your widget instances and their Ids. Because of the RemoteViews there is NO way to get some useful value from the Views of your widget (for example you can NOT read the counter value from the TextView) so you must use the provided information and DO persist your counter values per widget id. When the next onUpdate gets called you read the value from the storage, increase it, update the widget with the new value and then store the new value back.

D. If your widget has to do many things or slow things (like networking) when its time to update itself, you should consider using a service for this. But in your case (to increase a number) your approach is just fine as long as you persist the counters in the persistent storage or somewhere else.

Finally I 've noticed that in your onReceive override you are calling the "super.onReceive" only if you don't receive the "UPDATE_NUMBER" action. This is NOT a good practice, unless there is a GOOD reason (that's another story) always call super.onReceive as the first or the last command in your override.

Hope this helps...

Awesome, thanks so much! I learned more from you answer than hours of reading blog posts. What's the difference between calling super.onReceive() as the first or last command of the onReceive() method? I've always had that question regarding super. — Sandy, May 13 '12 at 16:14
Actually it depends from what you are doing. If you want for example to exit (by calling return;) the method somewhere in the middle of it then you have to call super first (before the return call) otherwise call it last. However there are other methods in Android (If I remember well, Activity's onDestroy) in which super.onDestroy must be called first. In my app-widgets I am calling super.onReceive as the last command... — ChD Computers, May 13 '12 at 16:21
In onReceive() I've modified touchCounter to equal a random value (like this: touchCounter = new Random().nextInt(100);) and commented out when the TextView is modified in onUpdate() but it still doesn't change the value. Am I missing anything else? — Sandy, May 13 '12 at 20:32

score 0 · Answer 2 · answered Jun 15 '23 at 20:43

I had a chance to create an AppWidget having vibration on touch. Here is my workable snippet (Just modify activity name and viewIds):

class MyWidgetProvider : AppWidgetProvider() {
companion object {
    const val TOUCH_ACTION = "com.tekelili.poe.TOUCH_ACTION"
    const val EXTRA_ITEM   = "com.tekelili.poe.t.EXTRA_ITEM"
}

override fun onUpdate(context: Context,appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
    for (appWidgetId in appWidgetIds) {
        updateMyAppWidget(context, appWidgetManager, appWidgetId)
    }
}

override fun onReceive(context: Context, intent: Intent) {
    if (intent.action == TOUCH_ACTION) {
        val index: Int = intent.getIntExtra(EXTRA_ITEM, 0)
        val myIntent = Intent(context, MockActivity::class.java)
            .putExtra("INDEX", index.toString())
            .setFlags(Intent.FLAG_ACTIVITY_NEW_TASK)

        (context.getSystemService(Context.VIBRATOR_SERVICE) as Vibrator).vibrate(100)
        context.startActivity(myIntent)
    }
    super.onReceive(context, intent)
}
internal fun updateMyAppWidget(context: Context, appWidgetManager: AppWidgetManager,appWidgetId: Int) {
    val views = RemoteViews(context.packageName, R.layout.mock_layout_widget)

    views.setOnClickPendingIntent(R.id.mock_textview,
                    getPendingIntent(context, appWidgetId, 123))
    appWidgetManager.updateAppWidget(appWidgetId, views)
}

private fun getPendingIntent(context: Context, appWidgetId: Int, value: Int): PendingIntent {
    val touchPendingIntent: PendingIntent = Intent(context, MyWidgetProvider::class.java).run {
        action = TOUCH_ACTION
        putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId)
        putExtra(EXTRA_ITEM, value)
        data = Uri.parse(toUri(Intent.URI_INTENT_SCHEME))
        PendingIntent.getBroadcast(context, 0, this, PendingIntent.FLAG_UPDATE_CURRENT)
    }
    return touchPendingIntent
}

}

Android widget not responding to touches

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