Question

I know it’s possible, but I can’t figure out a way to trigger an update of my widget from the main activity. Isn’t there some general intent I can broadcast?

Answer 1

If you are using an AppWidgetProvider, you can update it this way:

Intent intent = new Intent(this, MyAppWidgetProvider.class);
intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
// Use an array and EXTRA_APPWIDGET_IDS instead of AppWidgetManager.EXTRA_APPWIDGET_ID,
// since it seems the onUpdate() is only fired on that:
 int[] ids = AppWidgetManager.getInstance(getApplication())
    .getAppWidgetI‌​ds(new ComponentName(getApplication(), MyAppWidgetProvider.class));
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
sendBroadcast(intent);