android - Launching activity from widget

Question

I'm trying to do something which really ought to be quite easy, but it's driving me crazy. I'm trying to launch an activity when a home screen widget is pressed, such as a configuration activity for the widget. I think I've followed word for word the tutorial on the Android Developers website, and even a few unofficial tutorials as well, but I must be missing something important as it doesn't work.

Here is the code:

public class VolumeChangerWidget extends AppWidgetProvider {

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

    for (int i=0; i < N; i++) {
        int appWidgetId = appWidgetIds[i];

        Log.d("Steve", "Running for appWidgetId " + appWidgetId);
        Toast.makeText(context, "Hello from onUpdate", Toast.LENGTH_SHORT);
        Log.d("Steve", "After the toast line");

        Intent intent = new Intent(context, WidgetTest.class);

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

        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget);
        views.setOnClickPendingIntent(R.id.button, pendingIntent);

        appWidgetManager.updateAppWidget(appWidgetId, views);
    }
}

}

When adding the widget to the homescreen, Logcat shows the two debugging lines, though not the Toast. (Any ideas why not?) However, more vexing is that when I then click on the button with the PendingIntent associated with it, nothing happens at all. I know the "WidgetTest" activity can run because if I set up an Intent from within the main activity, it launches fine.

In case it matters, here is the Android Manifest file:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.steve"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".Volume_Change_Program"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".WidgetTest"
              android:label="@string/hello">
        <intent_filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.LAUNCHER"/>
        </intent_filter>
    </activity>

    <receiver android:name=".VolumeChangerWidget" >
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
        </intent-filter>
        <meta-data  android:name="android.appwidget.provider"
                    android:resource="@xml/volume_changer_info" />
    </receiver>

</application>
<uses-sdk android:minSdkVersion="3" />

Is there a way to test where the fault is? I.e. is the fault that the button isn't linked properly to the PendingIntent, or that the PendingIntent or Intent isn't finding WidgetTest.class, etc?

Thanks very much for your help!

Steve

Answer 1

Bringing this way back from the dead, but I had a similar problem and I think I finally solved it... like you, I had a PendingIntent that I attached to the RemoteView. Sometimes it would work, and sometimes it would fail. It was driving me crazy.

What I found from a tooltip on the PendingIntent.getActivty() was:

Note that the activity will be started outside of the context of an existing activity, so you must use the Intent.FLAG_ACTIVITY_NEW_TASK launch flag in the Intent.

so, I added:

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

No example code I've seen so far does this, but it solved my problem; the Settings activity is now launched reliably.

The full code that's working well...

Intent intent = new Intent(context, Settings.class);
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appId);  // Identifies the particular widget...
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Make the pending intent unique...
intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
PendingIntent pendIntent = PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);

RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.wwwidget);
views.setOnClickPendingIntent(R.id.widget, pendIntent);
appWidgetManager.updateAppWidget(appId,views);