ScrollView在布局内受“匹配约束”约束时不显示内容

Question

我的约束布局中有一个ScrollView，其中包含另一个约束布局，如果将其高度设置为“匹配约束”（即（0dp）），则视图不会显示其内容。如果我将其设置为类似400dp的硬编码，那么它将起作用。

我试图在测试应用程序中复制相同内容，但效果很好，但在我的应用程序中不起作用。

在主布局的末尾包含名为“ questionview”的滚动视图。

这是主要布局：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/fragmentExamLayout"
    android:padding="15dp"
    tools:context=".ui.examination.ExamSectionFragment">


    <com.google.android.material.tabs.TabLayout
        android:id="@+id/questionTab"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/exitTestButton"
        app:tabGravity="center"
        app:tabIndicatorColor="@color/colorPrimary"
        app:tabIndicatorGravity="top"
        app:tabIndicatorHeight="2dp"
        app:tabMinWidth= "@dimen/tab_min_width"
        app:tabMode="scrollable"
        app:tabRippleColor="@color/colorAccent"
        app:tabSelectedTextColor="@color/colorPrimary" />

    <TextView
        android:id="@+id/timerText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/timer"
        android:textAlignment="center"
        android:textColor="@color/colorPrimary"
        android:textSize="@dimen/question_text_size"
        app:autoSizeTextType="uniform"
        app:layout_constraintEnd_toStartOf="@+id/exitTestButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintHorizontal_chainStyle="spread_inside"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


    <Button
        android:id="@+id/exitTestButton"
        style="@android:style/Widget.DeviceDefault.Light.Button.Borderless.Small"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:text="@string/submit_test"
        android:textColor="#CF0A0A"
        app:layout_constraintBottom_toBottomOf="@+id/timerText"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/timerText"
        app:layout_constraintTop_toTopOf="@+id/timerText" />

    <TextView
        android:id="@+id/questionNumber"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:text="@string/QuestionNum"
        android:textSize="@dimen/heading_text_size"
        android:textStyle="bold"
        app:layout_constrainedHeight="false"
        app:layout_constraintEnd_toStartOf="@+id/questionMMarks"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintHorizontal_chainStyle="spread_inside"
        app:layout_constraintStart_toEndOf="@+id/include3"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/questionTab" />

    <TextView
        android:id="@+id/questionMMarks"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:text="@string/m_m"
        android:textSize="@dimen/heading_text_size"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="@+id/questionNumber"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/questionNumber" />

    <include
        android:id="@+id/include3"
        layout="@layout/questionview"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/questionNumber" />

</androidx.constraintlayout.widget.ConstraintLayout>

通过“ include”标签添加了ScrollView

这是滚动视图的代码：

<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    android:id="@+id/scrollView3"
    >

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:divider="@android:drawable/divider_horizontal_dim_dark"
        android:padding="16dp"
        android:showDividers="beginning">

        <TextView
            android:id="@+id/questionText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:ems="10"
            android:textSize="@dimen/question_text_size"
            app:autoSizeTextType="uniform"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.514"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <RadioGroup
            android:id="@+id/radioGroup"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginTop="32dp"
            android:layout_marginEnd="8dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/questionText">

            <RadioButton
                android:id="@+id/radioButton1"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/text_margin"
                android:text=""
                android:textSize="@dimen/radio_text_size"/>

            <RadioButton
                android:id="@+id/radioButton2"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/text_margin"
                android:text=""
                android:textSize="@dimen/radio_text_size"/>

            <RadioButton
                android:id="@+id/radioButton3"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/text_margin"
                android:text=""
                android:textSize="@dimen/radio_text_size"/>

            <RadioButton
                android:id="@+id/radioButton4"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/text_margin"
                android:text=""
                android:textSize="@dimen/radio_text_size"/>
        </RadioGroup>

        <Button
            android:id="@+id/saveAndNextButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginEnd="16dp"
            android:background="@drawable/buttonshape"
            android:paddingHorizontal="@dimen/button_padding_horizontal"
            android:text="@string/save_and_next"
            android:textColor="#FFFFFF"
            android:textSize="@dimen/buttton_text_size"
            app:layout_constraintBottom_toBottomOf="@+id/markReviewButton"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/markReviewButton"
            app:layout_constraintTop_toTopOf="@+id/markReviewButton"
            app:layout_constraintVertical_bias="0.396" />

        <Button
            android:id="@+id/markReviewButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginTop="36dp"
            android:layout_marginEnd="32dp"
            android:layout_marginBottom="24dp"
            android:background="@drawable/buttonshape"
            android:paddingHorizontal="@dimen/button_padding_horizontal"
            android:text="@string/mark_for_review"
            android:textColor="#FFFFFF"
            android:textSize="@dimen/buttton_text_size"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toStartOf="@+id/saveAndNextButton"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintHorizontal_chainStyle="spread_inside"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/radioGroup"
            app:layout_constraintVertical_bias="0.0" />


    </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.core.widget.NestedScrollView>

它应该看起来像这样：

Layout image

如果我将include中的布局高度更改为固定高度，例如400dp，如下所示：

 <include
        android:id="@+id/include3"
        layout="@layout/questionview"
        android:layout_width="0dp"
        

android：layout_height =“ 400dp”

        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/questionNumber" />

然后ScrollView可以正常工作。