如何正确使用ConstraintLayout？ViewPager2布局覆盖问题求助

布局包含TabLayout、ViewPager2和底部按钮栏，ViewPager2容器会覆盖其他界面元素导致显示异常。需要将ViewPager2放在TabLayout和按钮之间，适配空间且不覆盖其他UI，尝试绑定ViewPager2顶部到TabLayout底部、底部到按钮布局顶部后问题仍未解决。

原布局代码：

<?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"
    tools:context=".MainActivity">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/scheduleDaySelector"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">
    </com.google.android.material.tabs.TabLayout>

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/scheduleViewer"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        app:layout_constraintBottom_toTopOf="@id/menu"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/scheduleDaySelector" />

    <LinearLayout
        android:id="@+id/menu"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="1dp"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="1dp"
        android:orientation="horizontal"
        app:layout_constraintBottom_toBottomOf="@id/scheduleViewer"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <com.google.android.material.button.MaterialButton
            android:id="@+id/scheduleButton"
            style="@style/Widget.MaterialComponents.Button.TextButton.Icon"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="@string/schedule_button"
            app:icon="@drawable/ic_schedule_button"
            app:iconGravity="textStart" />

        <com.google.android.material.button.MaterialButton
            android:id="@+id/announcementButton"
            style="@style/Widget.MaterialComponents.Button.TextButton.Icon"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="@string/announcement_button"
            app:icon="@drawable/ic_announcement_button"
            app:iconGravity="textStart" />
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

解决方法 #

问题出在两处：

1. ViewPager2的高度设置为match_parent会强制占满父布局空间，忽略约束限制；
2. 底部按钮栏的约束错误绑定到了ViewPager2底部，导致布局依赖混乱。

修改步骤：

• 将ViewPager2的android:layout_height="match_parent"改为android:layout_height="0dp"，这样它会根据上下约束自动填充TabLayout和按钮栏之间的剩余空间；
• 将底部LinearLayout的app:layout_constraintBottom_toBottomOf="@id/scheduleViewer"改为app:layout_constraintBottom_toBottomOf="parent"，让按钮栏固定在屏幕底部。

修改后的完整布局代码：

<?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"
    tools:context=".MainActivity">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/scheduleDaySelector"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">
    </com.google.android.material.tabs.TabLayout>

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/scheduleViewer"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        app:layout_constraintBottom_toTopOf="@id/menu"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/scheduleDaySelector" />

    <LinearLayout
        android:id="@+id/menu"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="1dp"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="1dp"
        android:orientation="horizontal"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <com.google.android.material.button.MaterialButton
            android:id="@+id/scheduleButton"
            style="@style/Widget.MaterialComponents.Button.TextButton.Icon"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="@string/schedule_button"
            app:icon="@drawable/ic_schedule_button"
            app:iconGravity="textStart" />

        <com.google.android.material.button.MaterialButton
            android:id="@+id/announcementButton"
            style="@style/Widget.MaterialComponents.Button.TextButton.Icon"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="@string/announcement_button"
            app:icon="@drawable/ic_announcement_button"
            app:iconGravity="textStart" />
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

内容的提问来源于stack exchange，提问作者Егорий Зиемелис