Programmatically update widget from activity/service/receiver

This helped when I searched on how to update a widget from a service/or action (but may be possible from every Context):

Context context = this;
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_2x1);
ComponentName thisWidget = new ComponentName(context, MyWidget.class);
remoteViews.setTextViewText(R.id.my_text_view, "myText" + System.currentTimeMillis());
appWidgetManager.updateAppWidget(thisWidget, remoteViews);

If you are trying to programmatically update the widget where you do not have access to YourWidgetProvider.class explicitly, e.g. from another module or library, you can capture what YourWidgetProvider.class.getName() outputs and create a constant:

val WIDGET_CLASS_NAME = "com.example.yourapplication.YourWidgetProvider"

You would then be able to use this implicitly:

val intent = Intent(AppWidgetManager.ACTION_APPWIDGET_UPDATE)
val widgetManager = AppWidgetManager.getInstance(context)
val ids = widgetManager.getAppWidgetIds(ComponentName(context, WIDGET_CLASS_NAME))
AppWidgetManager.getInstance(context).notifyAppWidgetViewDataChanged(ids, android.R.id.list)
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids)
context.sendBroadcast(intent)

For reference, I had to do like this in a fragment:

Application app = getActivity().getApplication();
Intent intent = new Intent(context, RQWidget.class);
intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);

int[] ids = AppWidgetManager.getInstance(app).getAppWidgetIds(new ComponentName(app, RQWidget.class));
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
context.sendBroadcast(intent);

Example from my to-do list:

Intent intent = new Intent(this, TodosAppWidget.class);
intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
int[] ids = AppWidgetManager.getInstance(getApplication()).getAppWidgetIds(new ComponentName(getApplication(), TodosAppWidget.class));
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
sendBroadcast(intent);

sendBrodcast(Intent(this, TodosAppWidget::class.java).apply {
  action = AppWidgetManager.ACTION_APPWIDGET_UPDATE
  val ids = AppWidgetManager.getInstance(application).getAppWidgetIds(ComponentName(application, TodosAppWidget::class.java))
  putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids)
})