How can i determine that CollapsingToolbar is collapsed?

Question

I need to know when CollapsingToolbar from material design library is collapsed.

Answer 1

 appBarLayout.addOnOffsetChangedListener(AppBarLayout.OnOffsetChangedListener { appBarLayout, verticalOffset ->

        if (Math.abs(verticalOffset)  >= appBarLayout.totalScrollRange) { // collapse
        } else if (verticalOffset == 0) { // fully expand

        } else { // scolling

        }
    })

appBarLayout.totalScrollRange is not always equal to verticalOffset in some case, better check verticalOffset larger than totoalScrollRange