How to show BottomNavigationBar again on navigate back

问题

I'm using a BottomNavigationBar with HideBottomViewOnScrollBehavior to hide it when user scrolls down and display it when user scrolls up. This works great.

But how can i show the BottomNavigationBar again when it's hidden because user scrolled down and navigates back over back button?

At the moment my BottomNavigationView stays hidden.

I'm using support library 28.0.0

回答1:

Maybe somebody has a better solution for this, but for now i came up with the following.

In my MainActivity of my SingleActivity app i added the following function to simulate up scrolling:

fun ensureBottomNavigation() {
    if(bottomNavigationView.translationY != 0f) {
        val layoutParams = bottomNavigationView.layoutParams as CoordinatorLayout.LayoutParams
        val behavior = layoutParams.behavior as HideBottomViewOnScrollBehavior

        behavior.onNestedScroll(container, bottomNavigationView, host_fragment.view!!, 0, -1, 0, 0, 0)
    }
}

In every Fragment of my app i'm calling this function in onResume() like this:

override fun onResume() {
    super.onResume()

    // Ensure that bottom navigation view is visible onResume()
    (activity as MainActivity).ensureBottomNavigation()
}

来源：https://stackoverflow.com/questions/54865536/how-to-show-bottomnavigationbar-again-on-navigate-back