HorizontalScrollView: auto-scroll to end when new Views are added?

Question

I have a HorizontalScrollView containing a LinearLayout. On screen I have a Button that will add new Views to the LinearLayout at runtime, and I\'d like the scroll view to

Answer 1

I think there's a timing issue. Layout isn't done when a view is added. It is requested and done a short time later. When you call fullScroll immediately after adding the view, the width of the linearlayout hasn't had a chance to expand.

Try replacing:

s.fullScroll(HorizontalScrollView.FOCUS_RIGHT);

with:

s.postDelayed(new Runnable() {
    public void run() {
        s.fullScroll(HorizontalScrollView.FOCUS_RIGHT);
    }
}, 100L);

The short delay should give the system enough time to settle.

P.S. It might be sufficient to simply delay the scrolling until after the current iteration of the UI loop. I have not tested this theory, but if it's right, it would be sufficient to do the following:

s.post(new Runnable() {
    public void run() {
        s.fullScroll(HorizontalScrollView.FOCUS_RIGHT);
    }
});

I like this better because introducing an arbitrary delay seems hacky to me (even though it was my suggestion).