嵌套滚动视图中的recyclerview加载缓慢

Question

我的nestedscrollview 中有recyclerview，当我的recyclerview 加载时，滚动没有问题，它非常流畅，但一开始加载速度很慢（与我的数据或网络无关）慢行是recyclerview.adapter = MyAdapter()

当我将 recyclerview 移出 nestedscrollview（根元素的第一个子元素）时，它的速度非常快。这是我的xml

使用这个 xml，它会阻止 ui 3-4 秒并加载它，但如果我将我的 recyclerview 放在 nestedscrollview 之外，它会在几毫秒内加载，不明显。

我需要我的nestedscrollview 中的recyclerview。

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools" 
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusableInTouchMode="true"
        android:background="#f7f7f7"
        android:orientation="vertical">
        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:titleTextAppearance="@style/ToolbarExpandedTextAppearance"
            app:layout_collapseMode="pin"
            android:background="@color/colorPrimary">
            <ImageButton
                android:layout_width="?attr/actionBarSize"
                android:layout_height="?attr/actionBarSize"
                android:id="@+id/right_button"
                android:src="@drawable/ic_top_question"
                android:layout_gravity="end|top"
                android:contentDescription="@string/placeholder_right_button"
                android:background="?attr/selectableItemBackground"/>
        </androidx.appcompat.widget.Toolbar>

        <androidx.core.widget.NestedScrollView
            android:id="@+id/nestedScrollView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fillViewport="true"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"
            android:orientation="vertical">

            <androidx.constraintlayout.widget.ConstraintLayout
                android:layout_width="match_parent"
                android:orientation="vertical"
                android:layout_height="match_parent">

                <androidx.constraintlayout.widget.ConstraintLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@color/colorPrimary" android:id="@+id/constraintLayout">

                    <TextView
                        android:text="Give £8, Get £8"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textColor="@color/white"
                        android:textSize="@dimen/field_header_title_text"
                        android:fontFamily="@font/apercu_medium"
                        android:id="@+id/textView2" android:layout_marginTop="8dp"
                        android:layout_marginStart="16dp"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toTopOf="parent"/>
                    <TextView
                        android:text="Give your friends £8 with your code and get £8 for every friend that uses it!"
                        android:layout_width="0dp"
                        android:layout_height="wrap_content"
                        android:fontFamily="@font/apercu"
                        android:textSize="@dimen/discover_message_text_size"
                        android:textColor="@color/text_white"
                        android:lineSpacingExtra="10dp"
                        android:id="@+id/textView3" android:layout_marginTop="16dp"
                        app:layout_constraintTop_toBottomOf="@+id/textView2"
                        app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
                        android:layout_marginEnd="32dp" android:layout_marginStart="16dp"/>
                    <LinearLayout
                        android:orientation="horizontal"
                        android:layout_width="0dp"
                        android:layout_height="80dp"
                        app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
                        app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
                        android:layout_marginTop="24dp" app:layout_constraintTop_toBottomOf="@+id/textView3"
                        android:id="@+id/linearLayout" android:layout_marginBottom="8dp"
                        app:layout_constraintBottom_toBottomOf="parent">
                        <LinearLayout
                            android:orientation="vertical"
                            android:layout_width="0dp"
                            android:layout_weight="1"
                            android:layout_height="match_parent"
                            android:gravity="center"
                            android:layout_margin="8dp"
                            android:background="@drawable/white_radius">
                            <TextView
                                android:layout_width="match_parent"
                                android:fontFamily="@font/apercu_bold"
                                android:textColor="@color/warm_grey"
                                android:layout_height="wrap_content"
                                android:gravity="center"
                                android:textSize="24sp"
                                android:id="@+id/txt_pending_invites"/>
                            <TextView
                                android:text="Pending invites"
                                android:layout_width="match_parent"
                                android:fontFamily="@font/apercu"
                                android:lineSpacingExtra="10dp"
                                android:textColor="@color/greyish"
                                android:layout_height="wrap_content" android:id="@+id/textsView5"
                                android:gravity="center"/>
                        </LinearLayout>

                        <LinearLayout
                            android:orientation="vertical"
                            android:layout_width="0dp"
                            android:layout_weight="1"
                            android:gravity="center"
                            android:layout_margin="8dp"
                            android:layout_height="match_parent"
                            android:background="@drawable/white_radius">
                            <TextView
                                android:layout_width="match_parent"
                                android:fontFamily="@font/apercu_bold"
                                android:textColor="@color/warm_grey"
                                android:layout_height="wrap_content"
                                android:gravity="center"
                                android:textSize="24sp"
                                android:id="@+id/txt_earned"/>
                            <TextView
                                android:text="Total earned to date"
                                android:layout_width="match_parent"
                                android:fontFamily="@font/apercu"
                                android:lineSpacingExtra="10dp"
                                android:textColor="@color/greyish"
                                android:layout_height="wrap_content" android:id="@+id/textView5"
                                android:gravity="center"/>
                        </LinearLayout>

                    </LinearLayout>

                </androidx.constraintlayout.widget.ConstraintLayout>

                <androidx.constraintlayout.widget.ConstraintLayout
                        android:layout_width="match_parent"
                        android:layout_height="100dp"
                        tools:layout_editor_absoluteX="16dp" android:layout_marginTop="8dp"
                        app:layout_constraintTop_toBottomOf="@+id/constraintLayout"
                        android:id="@+id/constraintLayout3">

                    <androidx.constraintlayout.widget.ConstraintLayout
                            android:layout_width="0dp"
                            android:background="@drawable/edittextround"
                            android:layout_height="50dp" app:layout_constraintBottom_toBottomOf="parent"
                            android:layout_marginBottom="8dp" app:layout_constraintStart_toStartOf="parent"
                            android:layout_marginTop="8dp" app:layout_constraintTop_toTopOf="parent"
                            app:layout_constraintEnd_toEndOf="parent" android:layout_marginStart="15dp"
                            android:layout_marginEnd="15dp" android:id="@+id/constraintLayout2">
                        <TextView
                            android:id="@+id/txt_promo_code"
                            android:layout_width="0dp"
                            android:layout_height="wrap_content"
                            android:maxLines="1"
                            android:textSize="16sp"
                            android:text=""
                            android:textColor="@color/evergreen"
                            android:background="@android:color/transparent" android:layout_marginBottom="8dp"
                            app:layout_constraintBottom_toBottomOf="parent" android:layout_marginTop="8dp"
                            app:layout_constraintTop_toTopOf="parent"
                            app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="20dp"
                            app:layout_constraintEnd_toStartOf="@+id/invite_button"/>
                        <Button
                            android:text="Share"
                            android:layout_width="wrap_content"
                            android:background="@drawable/form_button_radius"
                            android:textAppearance="@style/BottomButtonAppearance"
                            android:layout_height="32dp"
                            android:id="@+id/invite_button"
                            app:layout_constraintEnd_toEndOf="parent"
                            android:layout_marginEnd="8dp" android:layout_marginBottom="0dp"
                            app:layout_constraintBottom_toBottomOf="parent" android:layout_marginTop="0dp"
                            app:layout_constraintTop_toTopOf="parent"/>

                    </androidx.constraintlayout.widget.ConstraintLayout>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:background="?android:colorBackground"
                        android:includeFontPadding="false"
                        android:paddingLeft="5dp"
                        android:paddingRight="5dp"
                        android:textSize="13sp"
                        android:text="Share Code"
                        android:textColor="@color/warm_grey"
                        android:fontFamily="@font/apercu"
                        android:textAppearance="@android:style/TextAppearance.Medium"
                        app:layout_constraintEnd_toEndOf="@+id/constraintLayout2"
                        app:layout_constraintStart_toStartOf="@+id/constraintLayout2"
                        app:layout_constraintHorizontal_bias="0.05" android:layout_marginTop="8dp"
                        app:layout_constraintTop_toTopOf="@+id/constraintLayout2"
                        app:layout_constraintBottom_toTopOf="@+id/constraintLayout2"/>

                </androidx.constraintlayout.widget.ConstraintLayout>

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="18sp"
                    android:textColor="@color/black"
                    android:letterSpacing="-0.01"
                    android:lineSpacingExtra="4sp"
                    android:text="Invite your contacts"
                    app:layout_constraintTop_toBottomOf="@+id/constraintLayout3"
                    android:layout_marginStart="16dp" app:layout_constraintStart_toStartOf="parent"
                    android:id="@+id/textView" android:layout_marginTop="12dp"/>

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:textColor="@color/warm_grey"
                    android:lineSpacingExtra="10sp"
                    android:visibility="gone"
                    android:text="Send your friends and family a link and you both get rewarded when they sign up."
                    android:layout_marginTop="12dp"
                    app:layout_constraintTop_toBottomOf="@+id/textView" android:id="@+id/txt_invite"
                    android:layout_marginStart="16dp" app:layout_constraintStart_toStartOf="parent"/>

                <androidx.constraintlayout.widget.ConstraintLayout
                    android:layout_width="match_parent"
                    android:layout_height="220dp"
                    android:background="@drawable/white_radius"
                    app:layout_constraintTop_toBottomOf="@+id/txt_invite"
                    app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="16dp"
                    app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="16dp"
                    android:id="@+id/permission_layout">
                    <Button
                        android:text="Give Access"
                        android:layout_width="0dp"
                        android:background="@drawable/form_button_radius"
                        android:textAppearance="@style/BottomButtonAppearance"
                        android:layout_height="48dp"
                        android:id="@+id/btn_give_access"
                        app:layout_constraintEnd_toEndOf="parent"
                        android:layout_marginEnd="16dp"
                        android:layout_marginStart="16dp"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toBottomOf="@+id/textView6" android:layout_marginTop="16dp"/>
                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textSize="13sp"
                        android:textColor="@color/warm_grey"
                        android:lineSpacingExtra="7sp"
                        android:gravity="center_horizontal"
                        android:text="@string/to_send_your_friends_and_family_a_referral_link_please_give_us_access_to_your_contacts"
                        tools:layout_editor_absoluteX="0dp"
                        android:layout_marginTop="16dp" app:layout_constraintTop_toBottomOf="@+id/imageView2"
                        android:id="@+id/textView6"/>
                    <ImageView
                        android:layout_width="60dp"
                        android:layout_height="60dp" app:srcCompat="@drawable/icon_person"
                        android:id="@+id/imageView2" android:layout_marginTop="20dp"
                        app:layout_constraintTop_toTopOf="parent" app:layout_constraintEnd_toEndOf="parent"
                        android:layout_marginEnd="8dp" app:layout_constraintStart_toStartOf="parent"
                        android:layout_marginStart="8dp"/>
                </androidx.constraintlayout.widget.ConstraintLayout>


                <androidx.recyclerview.widget.RecyclerView
                    android:id="@+id/contact_recycler"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    tools:listitem="@layout/item_contact"
                    tools:layout_editor_absoluteX="0dp" android:layout_marginTop="16dp"
                    app:layout_constraintTop_toBottomOf="@+id/permission_layout"/>

                <ProgressBar android:layout_width="wrap_content" android:layout_height="wrap_content"
                    app:layout_constraintTop_toBottomOf="@+id/permission_layout"
                    android:indeterminate="true"
                    android:indeterminateTintMode="src_atop"
                    android:indeterminateTint="@color/colorPrimary"
                    android:visibility="gone"
                    app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
                    app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="17dp"
                    android:progressTint="@color/warm_grey" android:layout_marginTop="24dp"
                    android:id="@+id/progress_bar"/>

            </androidx.constraintlayout.widget.ConstraintLayout>

        </androidx.core.widget.NestedScrollView>

    </LinearLayout>
<layout>

适配器代码

internal class ContactAdapter(context: Context, private val mProductList:   ArrayList<ContactModel>) : RecyclerView.Adapter<ContactAdapter.MyViewHolder>() {
    private val inflater: LayoutInflater;
    private val key: String? = null;

    init {
        inflater = LayoutInflater.from(context);
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        val view = inflater.inflate(R.layout.item_contact, parent, false);
        return MyViewHolder(view);
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int){
        val selectedProduct = mProductList[position];
        holder.setData(selectedProduct);

    }

    override fun getItemCount(): Int {
        return mProductList.size;
    }

    internal inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), View.OnClickListener {
        fun setData(selectedProduct: ContactModel)
        {
            itemView.txt_name.text = selectedProduct.name;
            itemView.txt_number.text = selectedProduct.number;
        }

        override fun onClick(v: View)
        {

        }
    }
}

Answer 1

我使用coordinatorlayout/collapsingtoolbar解决了这个问题。

Answer 2

这是一个常见问题，在嵌套滚动视图中使用回收器视图时的问题会导致未定义回收器视图高度，因此如果您在此回收器视图中显示 1000 个项目（嵌套滚动视图内的回收器视图）回收器适配器中的 onCreateViewHolder() 方法将被调用 1000 次，因为未确定此回收器的高度。
因此，要克服此问题，您必须使用

recyclerview.setNestedScrollingEnabled(false);

这将解决您的问题
另外，当回收器视图放置在嵌套滚动视图中时，最好为回收器视图定义一定的高度。