Scroll after view becomes visible

Question

I am trying to scroll to the bottom of my scrollView after a view becomes visible with button click. The problem is the scrollTo function is applied before the view is actually visible. I know this because when the button is pressed twice, it scrolls to the bottom on the second click. So, is there a way to scroll after the view becomes visible?

button.setOnClickListener(v -> {
    constraintLayout.setVisibility(View.VISIBLE);
    scrollView.smoothScrollTo(0, constraintLayout.getBottom());
}

Answer 1

Another option is to use a listener.

ViewTreeObserver.OnPreDrawListener viewVisibilityChanged = new ViewTreeObserver.OnPreDrawListener() {
    @Override
    public boolean onPreDraw() {
        if (my_view.getVisibility() == View.VISIBLE) {
            scroll_view.smoothScrollTo(0, scroll_view.getHeight());
        }
        return true;
    }
};

You can add it to your view this way :

my_view.getViewTreeObserver().addOnPreDrawListener(viewVisibilityChanged);