Change numColumns in GridView in Widget (RemoteViews) has no effect

Question

I have a widget(which works) with a GridView, which shows information in 1 or more columns/rows. I want to set the number of columns programmatically, cause the users shall choose. If I set the numColumns inside the Layout-XML to "1", it works fine. If I try to set the numColumns in the following way, it has no effect:

    rViews.setInt(R.id.duration_view, "setNumColumns", 1);

Layout looks like this:

    <GridView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/duration_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:minHeight="64dp"
        android:verticalSpacing="0dp"
        android:columnWidth="192dp"
        android:numColumns="auto_fit"
    />

My widget onUpdate() method, using the RemoteAdapter:

    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // ....
        Intent intent = new Intent(context, ViewFlipperWidgetService.class);
        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
        RemoteViews rViews = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
        rViews.setRemoteAdapter(R.id.duration_view, intent);
        rViews.setEmptyView(R.id.duration_view, R.id.empty_view);

        // This doesnt have any effect...:-(
        rViews.setInt(R.id.duration_view, "setNumColumns", 1); 

        appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId, R.id.duration_view);            

        AppWidgetManager.getInstance(context).updateAppWidget(appWidgetId, rViews);

        // ....
        super.onUpdate(context, appWidgetManager, appWidgetIds);

Not only the setNumColumns has no effect, other method calls as well. What I'm doing wrong?

Answer 1

The only methods you can call against a RemoteViews view are those with the @android.view.RemotableViewMethod annotation. There are only three such methods for GridView:

@android.view.RemotableViewMethod
public void setRemoteViewsAdapter(Intent intent) {

@android.view.RemotableViewMethod
public void smoothScrollToPosition(int position) {

@android.view.RemotableViewMethod
public void smoothScrollByOffset(int offset) {

You can verify this yourself:

https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/GridView.java