自定义View中RecyclerView偶现不显示问题求助

问题场景 #

以ConstraintLayout为根布局的自定义View内，RecyclerView存在间歇性显示异常：有时能正常加载展示数据，有时完全不显示。已在自定义View中手动设置LinearLayoutManager，但问题仍未解决，通过updateProducts方法更新RecyclerView数据。

原XML布局代码 #

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

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

        <View
            android:layout_width="@dimen/generic_dimen_0dp"
            android:layout_height="@dimen/generic_dimen_1dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:background="@color/tabs_border_gray"/>

        <androidx.appcompat.widget.AppCompatTextView
            android:id="@+id/recentlyViewedTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="@dimen/custom_margin_20dp"
            android:layout_marginTop="@dimen/generic_dimen_35dp"
            android:fontFamily="@font/es_web_med"
            android:textSize="16sp"
            android:padding="@dimen/custom_margin_5dp"
            android:text="Frequently Bought Together"
            android:textColor="@color/black"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toTopOf="@+id/productsRecycler"/>

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/productsRecycler"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:clipToPadding="false"
            android:orientation="horizontal"
            android:paddingHorizontal="@dimen/custom_margin_20dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
            tools:itemCount="4"
            tools:listitem="@layout/item_frequently_bought_together" />

    </androidx.constraintlayout.widget.ConstraintLayout>

</layout>

原自定义View Kotlin代码 #

class FrequentlyBoughtTogetherComponent @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = ZERO,
) : ConstraintLayout(context, attrs, defStyleAttr) {

    private val binding = FrequentlyBoughtTogetherComponentBinding.inflate(LayoutInflater.from(context), this, false)
    private var productsAdapter: FrequentlyBoughtTogetherAdapter? = null

    init {
        setView()
        addView(binding.root)
    }

    private fun setView() = binding.run {
        productsAdapter = FrequentlyBoughtTogetherAdapter()
        productsRecycler.layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)
        productsRecycler.adapter = productsAdapter
    }

    fun updateProducts(products: List<RecommendationProduct>) {
        productsAdapter?.submitList(products)
    }
}

解决办法 #

1. 修复自定义View布局加载逻辑 #

当前代码中，Binding inflate时已指定父布局为this，却又手动调用addView(binding.root)，导致布局嵌套重复，干扰测量流程。修改方式：
将inflate的第三个参数设为true，让系统自动将根布局挂载到自定义View，移除多余的addView调用。

修改后的Kotlin代码：

class FrequentlyBoughtTogetherComponent @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0,
) : ConstraintLayout(context, attrs, defStyleAttr) {

    private val binding: FrequentlyBoughtTogetherComponentBinding
    private var productsAdapter: FrequentlyBoughtTogetherAdapter? = null

    init {
        binding = FrequentlyBoughtTogetherComponentBinding.inflate(LayoutInflater.from(context), this, true)
        setView()
    }

    private fun setView() = binding.run {
        productsAdapter = FrequentlyBoughtTogetherAdapter()
        productsRecycler.layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)
        productsRecycler.adapter = productsAdapter
    }

    fun updateProducts(products: List<RecommendationProduct>) {
        productsAdapter?.submitList(products)
    }
}

2. 完善RecyclerView的约束关系 #

原XML中RecyclerView仅约束了左右和底部，未明确约束顶部与标题的关联，导致ConstraintLayout无法正确计算RecyclerView的高度范围。给RecyclerView添加顶部约束：

修改后的RecyclerView布局代码：

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/productsRecycler"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clipToPadding="false"
    android:orientation="horizontal"
    android:paddingHorizontal="@dimen/custom_margin_20dp"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/recentlyViewedTitle"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
    tools:itemCount="4"
    tools:listitem="@layout/item_frequently_bought_together" />

3. 验证ListAdapter的DiffUtil实现 #

如果使用ListAdapter，确保DiffUtil.ItemCallback的areItemsTheSame和areContentsTheSame方法逻辑正确，否则submitList可能无法触发数据更新。若暂时无法排查DiffUtil问题，可在updateProducts中临时添加notifyDataSetChanged()验证：

fun updateProducts(products: List<RecommendationProduct>) {
    productsAdapter?.submitList(products)
    productsAdapter?.notifyDataSetChanged()
}

注意：notifyDataSetChanged()是全局刷新，性能较差，仅用于排查问题，确认后仍需修复DiffUtil逻辑。

4. 强制触发RecyclerView重绘 #

在提交数据后，通过post方法触发RecyclerView重新测量布局，确保数据更新后界面能及时刷新：

fun updateProducts(products: List<RecommendationProduct>) {
    productsAdapter?.submitList(products)
    binding.productsRecycler.post {
        binding.productsRecycler.requestLayout()
    }
}

内容的提问来源于stack exchange，提问作者Alexis Rivas