如果片段包含AppBarLayout，则BottomNavigationView不会隐藏在内部片段中滚动

Question

我在使用Android中的coordinatorLayout在片段内滚动和检测它时遇到了很多问题。我有一个包含3个片段的“MainActivity”。在其中一个片段中，我有一个在滚动片段时折叠的Appbar。我已设法做到这一点，但如果我设置滚动行为以允许它，我的bottomNavigationView（在mainactivity.xml中找到）不会对滚动作出反应。代码是这样的：

Fragment1.xml

<android.support.design.widget.CoordinatorLayout
...
...>
    <android.support.design.widget.AppBarLayout
 ...
 ...>
        <android.support.design.widget.CollapsingToolbarLayout
                 app:layout_scrollFlags="scroll|exitUntilCollapsed"
   ...>
            <android.support.v7.widget.Toolbar
     .../>
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

   <android.support.v4.widget.NestedScrollView
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
   </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>

我的名字是c ty。 XML

<android.support.design.widget.CoordinatorLayout
.../>
    <FrameLayout
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
 .../>
    <android.support.design.widget.BottomNavigationView
      app:layout_behavior="@string/hide_bottom_view_on_scroll_behavior"
.../>
</android.support.design.widget.CoordinatorLayout>

现在，这种方法运行得很好，因为当我在内部滚动片段时，我的AppBar会折叠到标题中（这就是我想要的），但是我的bottomNavigationView对滚动没有反应。

我发现的是，如果我添加线

app:layout_behavior="@string/appbar_scrolling_view_behavior"

到AppBarLayout xml声明我得到bottomView在滚动事件上崩溃（当我向上滚动它再次显示）。所以基本上要么我能够在片段内折叠appbar，要么我能够在片段内部检测到滚动事件时隐藏BottomNavigationView。

任何形式的帮助将不胜感激。

Answer 1

为了隐藏底部导航以响应在片段内滚动修改片段1.kt上的qazxsw poi方法，如下所示

onCreateView

---

在Java中

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        ...

        // access the bottom nav which is on the main activity
        val bottomNav: BottomNavigationView = activity!!.findViewById(R.id.bottom_nav)

        // hide bottom nav when scrolling
        rvList.addOnScrollListener(object : RecyclerView.OnScrollListener() {

            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                if (dy > 0 || dy < 0) {
                    bottomNav.visibility = View.GONE
                }
            }

            override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
                if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                    bottomNav.visibility = View.VISIBLE
                }

                super.onScrollStateChanged(recyclerView, newState)
            }
        })

        return view
}

---

更新：

将侦听器代码提取到单独的函数，如下所示（在Kotlin中）

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
        ...

    // access the bottom nav which is on the main activity
    BottomNavigationView bottomNav = getActivity.findViewById(R.id.bottom_nav);

    // hide bottom nav when scrolling
    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener()
    {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy)
        {
             if (dy > 0 ||dy<0)
             {
                 bottomNav.setVisibility(View.GONE);
             }
        }

        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState)
        {
             if (newState == RecyclerView.SCROLL_STATE_IDLE)
             {
                  bottomNav.setVisibility(View.VISIBLE);
             }

             super.onScrollStateChanged(recyclerView, newState);
        }
    });

        return view;
 }

Answer 2

将您的库更新为

   public fun hideBottomNav(
        rvList: RecyclerView,
        bottomNav: BottomNavigationView
    ) {
        rvList.addOnScrollListener(object : RecyclerView.OnScrollListener() {

            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                if (dy > 0 || dy < 0) {
                    bottomNav.visibility = View.GONE
                }
            }

            override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
                if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                    bottomNav.visibility = View.VISIBLE
                }

                super.onScrollStateChanged(recyclerView, newState)
            }
        })
    }

或28.0.0 or above并更改您的androidx / material-1.0.0，如下所示 -

BottomNavigationView

希望它会有所帮助。