[Android] Launching activity from widget

Question

Hi,

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

When adding the widget to the homescreen, Logcat shows the two debugging lines, though not the Toast. (Any ideas why not?)

Don't try launching Toasts from a BroadcastReceiver.

Is there a way to test where the fault is?

Look at LogCat, via adb logcat, DDMS, or the DDMS perspective in Eclipse. You may find warnings about not finding an activity to match the given Intent.

I do not see any obvious problem. You may want to take a peek at one of my book examples and see if that works for you, and if it gives you any idea of what may be afoot.

Answer 2

The problem with the Toast not showing is easy, you don't call show(), a mistake I always do too... do

Toast.makeText(context, "Hello from onUpdate", Toast.LENGTH_SHORT).show();

instead of

Toast.makeText(context, "Hello from onUpdate", Toast.LENGTH_SHORT);

Answer 3

I was having the same issue. I discovered that the fix is to call an update through the appwidget manager. here is an example of how to do that in onEnabled. It appears it needs to be done in both onEnabled and onUpdated so that when device is powering on your click intent is also intialized - in onUpdated the params already provide the reference to the manager, luckily.

@Override 
    public void onEnabled(Context context) {  
          //Log.v("toggle_widget","Enabled is being called"); 

          AppWidgetManager mgr = AppWidgetManager.getInstance(context); 
          //retrieve a ref to the manager so we can pass a view update 

          Intent i = new Intent(); 
          i.setClassName("yourdoman.yourpackage", "yourdomain.yourpackage.yourclass"); 
          PendingIntent myPI = PendingIntent.getService(context, 0, i, 0); 
          //intent to start service 

        // Get the layout for the App Widget 
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.togglelayout); 

        //attach the click listener for the service start command intent 
        views.setOnClickPendingIntent(R.id.toggleButton, myPI); 

        //define the componenet for self 
        ComponentName comp = new ComponentName(context.getPackageName(), ToggleWidget.class.getName()); 

        //tell the manager to update all instances of the toggle widget with the click listener 
        mgr.updateAppWidget(comp, views); 
} 

Answer 4

Hi Steve, Me new to android ,actually i have a application and now my concern is 1) How do i create a home screen widget(With just a icon and a text view under it) 2) And when the widget on the home screen is clicked how do i show up my application would be looking forward for your help Thank you

Answer 5

Steve,

Have you found the problem? I use widget and it works fine for me without onEnabled trick. I'm interested why it doesn't for you.

My guess: in your original code please try

PendingIntent pendingIntent = PendingIntent.getActivity(context, 1, intent, 0);

instead of

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

Answer 6

Hi Steve; you must define your configuration activity in res/xml/volume_changer_info.xml. Add this tag and give a fully qualified path to the configuration activity.

android:configure = ""

---

e.g.

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minWidth="200dip"
    android:minHeight="100dip"
    android:updatePeriodMillis="60000"
    android:initialLayout="@layout/widget_loading"
    android:configure = "org.raza.ConfigureWidgetActivity"/>