java - Clickable widgets in android

Question

The developer documentation has seemed to have failed me here. I can create a static widget without thinking, I can even create a widget like the analogue clock widget that will update itself, however, I can not for the life of me figure out how to create a widget that reacts to when a user clicks on it. Here is the best code sample that the developer documentation gives to what a widget activity should contain (the only other hint being the API demos, which only creates a static widget):

public class ExampleAppWidgetProvider extends AppWidgetProvider {
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        final int N = appWidgetIds.length;

        // Perform this loop procedure for each App Widget that belongs to this provider
        for (int i=0; i<N; i++) {
            int appWidgetId = appWidgetIds[i];

            // Create an Intent to launch ExampleActivity
            Intent intent = new Intent(context, ExampleActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

            // Get the layout for the App Widget and attach an on-click listener to the button
            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider_layout);
            views.setOnClickPendingIntent(R.id.button, pendingIntent);

            // Tell the AppWidgetManager to perform an update on the current App Widget
            appWidgetManager.updateAppWidget(appWidgetId, views);
        }
    }
}

from: The Android Developer Documentation's Widget Page

So, it looks like pending intent is called when the widget is clicked, which is based off of an intent (I'm not quite sure what the difference between an intent and a pending intent is), and the intent is for the ExampleActivity class. So I made my sample activity class a simple activity that when created, would create a mediaplayer object, and start it (it wouldn't ever release the object, so it would eventually crash, here is it's code:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    MediaPlayer mp = MediaPlayer.create(getApplicationContext(), R.raw.sound);
    mp.start();
}

However, when I added the widget to the home screen, and clicked on it, nothing played, in fact, nothing played when I set the update timer to just a few hundred milliseconds (in the appwidget provider xml file). Furthermore, I set break points and found out that not only was it never reaching the activity, but no break points I set would ever get triggered. (I still haven't figured out why that is), however, logcat seemed to indicate that the activity class file was being run.

So, is there anything I can do to get an appwidget to respond to a click? As the onClickPendingIntent() method is the closest I have found to a onClick type of method.

Answer 1

First, add a static variable with a constant.

public static String YOUR_AWESOME_ACTION = "YourAwesomeAction";

Then you need to add the action to the intent before you add the intent to the pending intent:

Intent intent = new Intent(context, widget.class);
intent.setAction(YOUR_AWESOME_ACTION);

(Where widget.class is the class of your AppWidgetProvider, your current class)

You then need to create a PendingIntent with getBroadcast

PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);

Set the onClickPendingIntent for the clickable view in your widget

remoteView.setOnClickPendingIntent(R.id.widgetFrameLayout, pendingIntent);

Next, override the onReceive method in the same class:

@Override
public void onReceive(Context context, Intent intent) {
 super.onReceive(context, intent);

And then respond to your button presses by querying the intent returned for your action within the onReceive method:

if (intent.getAction().equals(YOUR_AWESOME_ACTION)) {
   //do some really cool stuff here
}

And that should do it!