android - fragment 中的 Recyclerview 位于 nestedscrollview 滚动问题内

Question

在 Activity 中，我有 TabLayout 和 FrameLayout 用于加载 fragment 。 fragment 包含 RecyclerView。它只适用于第一次。但是当我更改选项卡并返回到上一个选项卡时，RecyclerView 没有完全滚动。

Main Activity

<android.support.v4.widget.NestedScrollView
   android:fillViewport="true"
   android:layout_height="match_parent"
   android:layout_width="match_parent">

  <LinearLayout
   android:layout_height="match_parent"
   android:layout_width="match_parent"
   android:orientation="vertical">

   <android.support.design.widget.TabLayout
       android:id="@+id/tabMain"
       android:layout_height="wrap_content"
       android:layout_width="match_parent" />

   <FrameLayout
       android:id="@+id/containerMain"
       android:layout_height="match_parent"
       android:layout_width="match_parent" />
   </LinearLayout>
 </android.support.v4.widget.NestedScrollView>

Fragment

<LinearLayout
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical">

   <android.support.v7.widget.RecyclerView
       android:id="@+id/rvMedia"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:nestedScrollingEnabled="false" />
</LinearLayout>

Answer 1

The recyclerView has a smooth scrolling by itself but when we need to put recyclerView within any scrollView it will not work like the below:

Layout XML

 <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/recyclerView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </LinearLayout>
    </ScrollView>
</LinearLayout>

The solution for this is we need to used nestedScrollView instead of scrollview like the below

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

   <android.support.v4.widget.NestedScrollView
        android:id="@+id/nestedScrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:overScrollMode="never">


        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/recyclerView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </LinearLayout>
     </android.support.v4.widget.NestedScrollView>
</LinearLayout>

The problem occurs when we use nestedScrollView and put recyclerView inside nestedScrollView is, it scrolls in various speed depending on gesture. The scrolling feature will not be smooth.

So to fix this issue all you have to do after setting your adapter is to add this line ViewCompat.setNestedScrollingEnabled(recyclerView, false);

这不是一个好的解决方案。将 RecyclerView 放置在 NestedScrollView 中，会导致渲染 RecyclerView 适配器的所有元素，这会占用大量内存。在大多数内存较少的设备中，这可能会很慢。

这种方法也可能导致禁用需要滚动，这将禁用 View 回收，因此所有项目将立即初始化。例如在包含 1000 个项目的列表中。这将使应用程序滞后。如果在用户向下滚动列表时加载固定数量的项目时使用分页，则可以避免这种情况。

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Pagination with RecyclerView – Etienne Lawlor – Medium

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