android - ConstraintLayout 中的 RecyclerView 显示不正确

Question

我用链接、Guideline 和 Barrier 测试了这个 xml，但它们都无济于事。

xml代码:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    tools:context=".RatingActivity">

    <TextView
        android:id="@+id/welcomeTextView"
        android:layout_width="0dp"
        android:layout_height="74dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="79dp"
        android:gravity="clip_vertical|center_horizontal"
        android:text="@string/welcome"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/recyclerView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="467dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="24dp"
        android:background="@android:color/darker_gray"
        android:padding="4dp"
        android:scrollbars="vertical"
        app:layout_constraintBottom_toTopOf="@+id/submitButton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/submitButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"
        android:text="@string/submit"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

当它在 AVD 上运行时，RecyclerView 占用的空间比需要的多，导致它覆盖或推回 welcomeTextView 或提交按钮。

顺便说一句，这是 Gradle 依赖项:

implementation 'com.android.support.constraint:constraint-layout:1.1.3'

Answer 1

尝试:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <TextView
        android:id="@+id/welcomeTextView"
        android:layout_width="0dp"
        android:layout_height="74dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="79dp"
        android:gravity="clip_vertical|center_horizontal"
        android:text="welcome"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="24dp"
        android:background="@android:color/darker_gray"
        android:padding="4dp"
        android:scrollbars="vertical"
        app:layout_constrainedHeight="true"
        app:layout_constraintTop_toBottomOf="@+id/welcomeTextView"
        app:layout_constraintBottom_toTopOf="@id/submitButton" />

    <Button
        android:id="@+id/submitButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"
        android:text="submit"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

唯一的变化是将 RecyclerView 的顶部设置为文本的底部，然后将 RecyclerView 的高度设置为 0 并设置 app:layout_constrainedHeight="true" 以启用高度计算基于约束。如果欢迎消息底部边距不起作用，请尝试为 RecyclerView 设置顶部边距。