What the difference to update Android App Widget between two approach?

I read some example in internet/book about the App Widget, a normal example to update the widget is in onUpdate(Context context, AppWidgetManager appWidgetManager,int[] appWidgetIds) method of AppWidgetProvider like this:

final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
 int appWidgetId = appWidgetIds[i];
 RemoteViews updateViews = new RemoteViews(context.getPackageName(), R.layout.mywidget_layout);开发者_如何学Python
 updateViews.setTextViewText(R.id.mytext, "updated text");

 appWidgetManager.updateAppWidget(appWidgetId, updateViews);    
}

It update each Widgets in a loop.

But now, I have to implement an App Widget, it is updated in BroadcastReceiver, onReceive(Context context, Intent intent) method since there are no int[] appWidgetIds passed in. So I implemented the code like this:

RemoteViews updateViews = new RemoteViews(context.getPackageName(), R.layout.mywidget_layout);
updateViews.setTextViewText(R.id.mytext, "updated text");

ComponentName myComponentName = new ComponentName(context, AndroidBatteryWidgetProvider.class);
AppWidgetManager manager = AppWidgetManager.getInstance(context);
manager.updateAppWidget(myComponentName, updateViews);

It didn't update widget one-by-one, but actually all widgets were updated at once. Even though it worked as I want, but I got confused as to why there is no need to update all widgets one-by-one as before.

What's the difference between two methods?

Can I send another broadcast from BroadcastReceiver.onReceive() to trigger AppWidgetProvider.onUpdate()? And how to?

It's the same thing. Update with ComponentName loops through all the ids like your first code block.

You can see it in the Android code here:

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.0.4_r1.2/com/android/server/AppWidgetService.java#AppWidgetService.updateAppWidgetProvider%28android.content.ComponentName%2Candroid.widget.RemoteViews%29