Save / restore recyclerview state for Android (after screen rotation) - example

RecyclerViewExample.kt

    private val ARGS_SCROLL_STATE = "recyclerState"

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)

        outState.putParcelable(ARGS_SCROLL_STATE, recyclerView.getLayoutManager()?.onSaveInstanceState())
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        var recyclerViewState : Parcelable? = savedInstanceState?.getParcelable(ARGS_SCROLL_STATE)
        val recycler = RecyclerDBGeneric<EntityDBItem>(R.layout.card_history)

        recyclerView.apply {
            layoutManager = LinearLayoutManager(context)
            adapter = recycler
        }

        viewModel.dbItemsList.observe(viewLifecycleOwner, Observer {
            // showToast("Tasks: " + it.size)
            recycler.setItemList(it)
            recyclerViewState?.let {
                recyclerView.getLayoutManager()?.onRestoreInstanceState(it)
                recyclerViewState = null // to prevent state restoration on list updates
            }
        })
    }