Question

在开发具有以下层次结构的布局时，我遇到了RealmRecyclerViewAdapter的问题：

>CoordinatorLayout
-->NestedScrollView 
----> ConstraintLayout 
------> RecyclerView

问题是，首次启动时，RecyclerView在将数据插入Realm后不会显示其子节点。

我的 fragment_layout.xml

    <?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:elevation="0dp">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay" >

            <ImageView
                android:id="@+id/mainLogo"
                android:layout_width="96dp"
                android:layout_height="48dp"
                android:layout_gravity="center|top"
                android:src="@drawable/ic_logo"
                tools:ignore="ContentDescription"/>

        </android.support.v7.widget.Toolbar>

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

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v4.view.ViewPager
                android:id="@+id/pager"
                android:layout_width="match_parent"
                android:layout_height="184dp"
                android:background="@color/colorLightGray"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"/>

            <android.support.design.widget.TabLayout
                android:id="@+id/tabDots"
                android:layout_width="wrap_content"
                android:layout_height="24dp"
                android:layout_alignParentBottom="true"
                app:layout_constraintBottom_toBottomOf="@+id/pager"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:tabBackground="@drawable/tab_selector"
                app:tabGravity="center"
                app:tabIndicatorHeight="0dp"
                app:tabPadding="2dp"
                app:tabPaddingEnd="2dp"
                tools:ignore="RtlSymmetry"/>

            <Button
                android:id="@+id/btnGuideOrder"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginEnd="1dp"
                android:layout_marginLeft="16dp"
                android:layout_marginRight="1dp"
                android:layout_marginStart="16dp"
                android:layout_marginTop="16dp"
                style="@style/BtnBlock.Left"
                android:text="@string/btn_guide_order"
                app:layout_constraintEnd_toStartOf="@+id/btnGuidePay"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintHorizontal_chainStyle="spread"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/pager"/>

            <Button
                android:id="@+id/btnGuidePay"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginEnd="16dp"
                android:layout_marginRight="@dimen/spacing_normal"
                android:layout_marginTop="16dp"
                style="@style/BtnBlock.Right"
                android:text="@string/btn_guide_pay"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toEndOf="@+id/btnGuideOrder"
                app:layout_constraintTop_toBottomOf="@+id/pager"/>

            <android.support.v7.widget.RecyclerView
                android:id="@+id/recycler"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_marginBottom="32dp"
                android:layout_marginTop="16dp"
                android:background="@color/colorPrimary"
                android:nestedScrollingEnabled="false"
                android:paddingEnd="@dimen/spacing_product"
                android:paddingLeft="@dimen/spacing_product"
                android:paddingRight="@dimen/spacing_product"
                android:paddingStart="@dimen/spacing_product"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/btnGuideOrder"
                tools:ignore="UnusedAttribute"
                tools:listitem="@layout/item_product"/>

        </android.support.constraint.ConstraintLayout>

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

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

设置RecyclerView：

private fun setupRecycler() {
    fetchProducts(RetrofitManager.homeCategoryId)
    val products = realm.where(Product::class.java).findAll()
    rvAdapter = RealmProductAdapter(products)

    recycler.apply {
        adapter = rvAdapter
        layoutManager = GridLayoutManager(activity, 2)
        setHasFixedSize(true)
    }
}

获取数据：

private fun fetchProducts(categoryId: Int) {
    val mContext = context ?: return
    showProgress()

    val disposable = RetrofitManager.createService(mContext, IctService::class.java)
            .getCategoryProducts(authHeader(), categoryId)
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe({

                Log.d(_tag, "products, on Next")

                realm.executeTransaction { _ ->
                    realm.copyToRealmOrUpdate(it)
                }

                hideProgress()
            }, { error ->
                Log.e(_tag, "error: $error, ${error.stackTrace}")

                showErrorDialog { fetchProducts(categoryId) }
                hideProgress()
            })
    compositeDisposable?.add(disposable)
}

到目前为止我尝试了什么？

我已经检查过RealmRecyclerViewAdapter在数据插入领域时在内部调用notifyItemRangeInserted，但它没有更新布局。仅在触发ChangeListener时手动调用适配器上的notifyDataSetChanged强制Recycler显示其内容。
```
products.addChangeListener { results, changeSet ->
    Log.d(_tag, "setupRecycler, realmChangeListener, results: $results, set: $changeSet")
    rvAdapter.notifyDataSetChanged()
}
```
将ConstraintLayout替换为另一个（LinearLayout）并不能解决问题。但是如果我将RecyclerView直接放在CoordinatorLayout中 - 它会在数据插入Realm后立即显示它的子节点。所以问题与RecyclerView只是NestedScrollView的子项有关。

NestedScrollView中的RealmRecyclerViewAdapter在第一次启动时没有显示它的内容

0 个答案: