通过数据绑定使用时 OnScrollListener 不工作

Question

我正在尝试使用 onScrollListener 来隐藏 BottomNavigationView 和 mainActivity 的其他 UI 元素。而我的 recyclerview 位于 mainActivity 内的片段中，我正在使用自定义绑定适配器来膨胀 recyclerview。我目前正在使用数据绑定。

我的代码

class HomeFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        // Inflate the layout for this fragment
        val binding= FragmentHomeBinding.inflate(inflater,container,false)
        hideFloatingActionButton()

        binding.dataList = DataProvider.productList

        return binding.root

    }

    private fun hideFloatingActionButton(){

        rv_products?.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                if (dy > 0) {
                    // Scrolling up
                    Toast.makeText(activity,"Going upp", Toast.LENGTH_SHORT).show()

//                    if (fab_button.visibility==View.INVISIBLE){
//                        fab_button.visibility=View.VISIBLE
//                    }

                    if (bottomNav.visibility==View.INVISIBLE){
                        bottomNav.visibility=View.VISIBLE
                    }


                } else {
                    // Scrolling down
//                    if (fab_button.visibility==View.VISIBLE){
//                        fab_button.visibility=View.INVISIBLE
//                    }
                }

                if (bottomNav.visibility==View.VISIBLE){
                    bottomNav.visibility=View.INVISIBLE
                }
            }

            override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
                super.onScrollStateChanged(recyclerView, newState)

                if (newState == AbsListView.OnScrollListener.SCROLL_STATE_FLING) {
                    // Do something
                    Toast.makeText(activity,"Going upp", Toast.LENGTH_SHORT).show()

                } else if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
                    // Do something
                } else {
                    // Do something
                }
            }
        })


    }



}

回收站视图

Answer 1

首先从 data binding 对象中获取 recyclerView，然后使用 addOnScrollListener。声明一个实例变量private lateinit var binding: FragmentHomeBinding并在onCreateView()binding= FragmentHomeBinding.inflate(inflater,container,false).

里面初始化

现在在 hideFloatingActionButton() 方法中获取 recyclerView，如 binding.rvProducts.addOnScrollListener(your callback)

通过数据绑定使用时 OnScrollListener 不工作

OnScrollListener not working when used via databinding

android

kotlin

android-recyclerview

kotlin-android-extensions

android-databinding