约束布局内回收器视图的问题

Question

我正在尝试创建一个基于复杂布局的底部表单对话框。我必须实现的是一个带有标题布局的对话框、一个带有元素列表的回收器视图和一个带有几个按钮的底部栏。这是我的代码：

<?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">

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

        <!-- Layout injected inside this linear layout container programmatically -->
        <LinearLayout
            android:id="@+id/header_dialog_container"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintBottom_toTopOf="@id/form_dialog_recycler_view"
            app:layout_constraintTop_toTopOf="parent" />

        <android.support.v7.widget.RecyclerView
            android:id="@+id/form_dialog_recycler_view"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:scrollbars="vertical"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"
            app:layout_constraintBottom_toTopOf="@id/bottom_sheet_container_buttons"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/header_dialog_container" />

        <LinearLayout
            android:id="@+id/bottom_sheet_container_buttons"
            android:layout_width="match_parent"
            android:layout_height="60dp"
            android:orientation="horizontal"
            app:layout_constraintBottom_toBottomOf="parent">

            <Button
                android:id="@+id/dialog_sheet_button_reset"
                style="@style/ActionSheetTitle"
                android:layout_width="0dp"
                android:layout_height="60dp"
                android:layout_weight="0.5"
                android:background="@color/bottomBarContainerColor"
                android:text="@string/general_reset"
                android:textColor="@color/dangerColor" />

            <Button
                android:id="@+id/dialog_sheet_button_close"
                style="@style/ActionSheetTitle"
                android:layout_width="0dp"
                android:layout_height="60dp"
                android:layout_weight="0.5"
                android:background="@color/bottomBarContainerColor"
                android:text="@string/general_close" />

        </LinearLayout>
    </android.support.constraint.ConstraintLayout>
</layout>

不幸的是，我的回收器视图高度始终等于零。我尝试更改android:layout_height="0dp"为android:layout_height="wrap_content"，但正如预期的那样，它位于底部容器下方。我错过了什么吗？

Answer 1

试试看app:layout_constraintHeight_default="wrap"是否RecyclerView在里面ConstraintLayout。

Answer 2

试试这个代码：

<?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">

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

        <!-- Layout injected inside this linear layout container programmatically -->
        <LinearLayout
            android:id="@+id/header_dialog_container"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintBottom_toTopOf="@id/form_dialog_recycler_view"
            app:layout_constraintTop_toTopOf="parent" />

        <android.support.v7.widget.RecyclerView
            android:id="@+id/form_dialog_recycler_view"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:scrollbars="vertical"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"
            app:layout_constraintBottom_toTopOf="@id/bottom_sheet_container_buttons"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/header_dialog_container" />

        <LinearLayout
            android:id="@+id/bottom_sheet_container_buttons"
            android:layout_width="match_parent"
            android:layout_height="60dp"
            android:orientation="horizontal"
            app:layout_constraintBottom_toBottomOf="parent">

            <Button
                android:id="@+id/dialog_sheet_button_reset"
                style="@style/ActionSheetTitle"
                android:layout_width="0dp"
                android:layout_height="60dp"
                android:layout_weight="0.5"
                android:background="@color/bottomBarContainerColor"
                android:text="@string/general_reset"
                android:textColor="@color/dangerColor" />

            <Button
                android:id="@+id/dialog_sheet_button_close"
                style="@style/ActionSheetTitle"
                android:layout_width="0dp"
                android:layout_height="60dp"
                android:layout_weight="0.5"
                android:background="@color/bottomBarContainerColor"
                android:text="@string/general_close" />

        </LinearLayout>
    </android.support.constraint.ConstraintLayout>
</layout>