Android布局问题：调整creatorEditorContainer至closeButton下方

问题回顾 #

你当前遇到的问题是：当peopleList（RecyclerView）设为View.GONE时，creatorEditorContainer因为被设置为layout_height="0dp"且底部约束到已隐藏的RecyclerView，导致它被拉伸到屏幕中间，无法紧贴closeButton下方显示。

功能需求确认 #

• 同一屏幕内包含EditText和RecyclerView，点击@人图标时，RecyclerView需从tagPlaceholder顶部弹出并扩展至creatorContainer所在的creatorEditorContainer底部；
• 当RecyclerView的visibility设为View.GONE时，creatorContainer需紧邻closeButton显示。

解决方案 #

我们需要调整creatorEditorContainer和peopleList的约束及高度设置，具体修改点如下：

1. 修复creatorEditorContainer的定位问题 #

• 将layout_height从0dp改为wrap_content：NestedScrollView本身是用来包裹可滚动内容的，设置为wrap_content可以让它根据内部内容自适应高度，避免被不必要的约束拉伸；
• 移除app:layout_constraintBottom_toTopOf="@id/peopleList"：当RecyclerView隐藏时，这个约束会失效，导致容器的底部没有锚点，进而被拉伸；
• 添加app:layout_constraintBottom_toTopOf="@id/tagPlaceholder"：让容器底部锚定到tagPlaceholder的顶部，这样无论RecyclerView是否显示，容器都能保持在正确的位置，紧贴closeButton下方。

2. 调整RecyclerView的弹出约束 #

• 将peopleList的layout_height设为0dp：这样当它显示时，会自动填充creatorEditorContainer底部到tagPlaceholder顶部的整个空间，满足"从tagPlaceholder顶部弹出并扩展至creatorEditorContainer底部"的需求；
• 保留app:layout_constraintTop_toBottomOf="@id/creatorEditorContainer"和app:layout_constraintBottom_toTopOf="@id/tagPlaceholder"这两个约束，确保显示时的正确拉伸范围；
• 保持默认visibility="gone"，点击@图标时动态切换为visible即可。

修改后的完整布局代码 #

<androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" >
    <androidx.appcompat.widget.AppCompatImageButton android:id="@+id/closeButton" android:layout_width="@dimen/margin_48" android:layout_height="@dimen/margin_48" android:background="@android:color/white" android:paddingEnd="@dimen/margin_zero" android:paddingStart="@dimen/margin_small" android:paddingTop="@dimen/margin_small" android:src="@drawable/ic_close" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" />
    <androidx.appcompat.widget.AppCompatTextView android:id="@+id/screenTitle" android:layout_width="@dimen/margin_zero" android:layout_height="wrap_content" android:text="@string/label_create_post" android:textAppearance="@style/SubtitleAppearance" android:textColor="@android:color/black" android:textSize="@dimen/text_large" app:layout_constraintBottom_toBottomOf="@id/closeButton" app:layout_constraintEnd_toStartOf="@id/submitPost" app:layout_constraintStart_toEndOf="@id/closeButton" app:layout_constraintTop_toTopOf="@id/closeButton" />
    <androidx.appcompat.widget.AppCompatTextView android:id="@+id/submitPost" android:layout_width="@dimen/margin_48" android:layout_height="@dimen/margin_huge" android:layout_marginEnd="@dimen/margin_larger" android:layout_marginStart="@dimen/margin_larger" android:text="@string/label_post" app:layout_constraintBottom_toBottomOf="@id/screenTitle" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="@id/screenTitle" style="@style/PrimaryButton" />
    <androidx.core.widget.NestedScrollView android:id="@+id/creatorEditorContainer" android:layout_width="match_parent" android:layout_height="wrap_content" app:layout_constraintTop_toBottomOf="@id/closeButton" android:layout_marginTop="@dimen/margin_big" app:layout_constraintBottom_toTopOf="@id/tagPlaceholder" app:layout_behavior="@string/appbar_scrolling_view_behavior" >
        <androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" >
            <LinearLayout android:id="@+id/creatorContainer" app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="parent" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:paddingTop="@dimen/margin_medium" android:paddingBottom="@dimen/margin_medium" >
                <androidx.appcompat.widget.AppCompatImageView android:id="@+id/postCreatorImage" android:layout_width="@dimen/margin_40" android:layout_height="@dimen/margin_40" android:layout_marginStart="@dimen/margin_larger" android:src="@drawable/ic_man" tools:src="@drawable/ic_man" />
                <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" >
                    <androidx.appcompat.widget.AppCompatTextView android:id="@+id/creatorName" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="@dimen/margin_big" android:textAppearance="@style/SubtitleAppearance" android:textColor="@android:color/black" android:text="Name" tools:text="Mahesh Nandam" />
                    <androidx.appcompat.widget.AppCompatTextView android:id="@+id/creatorDesignation" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="@dimen/margin_big" android:textColor="@color/colorTextGrey" android:text="peopleDesignation" tools:text="Senior Development Engineer" style="@style/BodyAppearanceRegular" />
                </LinearLayout>
            </LinearLayout>
            <androidx.appcompat.widget.AppCompatEditText android:id="@+id/feedInput" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="@dimen/margin_15" android:background="@android:color/white" android:gravity="top" android:hint="@string/compose_hint" android:paddingEnd="@dimen/margin_larger" android:paddingStart="@dimen/margin_larger" android:textAppearance="@style/BodyAppearanceRegular" android:textColor="@color/colorTextGrey" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@id/creatorContainer" android:textSize="@dimen/text_medium" tools:text="Calling all ML and AI enthusiasts." />
        </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.core.widget.NestedScrollView>
    <androidx.recyclerview.widget.RecyclerView android:visibility="gone" android:id="@+id/peopleList" android:layout_width="match_parent" android:layout_height="0dp" app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" app:layout_constraintBottom_toTopOf="@id/tagPlaceholder" app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toBottomOf="@id/creatorEditorContainer" tools:itemCount="7" tools:listitem="@layout/item_people_profile_meta" app:adapter="@{fragFeedViewModel.getAdapterPeopleListAdapter()}" />
    <androidx.appcompat.widget.AppCompatEditText android:id="@+id/tagPlaceholder" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="&#64;" android:gravity="end" app:layout_constraintStart_toStartOf="parent" app:layout_constraintBottom_toBottomOf="parent" android:textAppearance="@style/BodyAppearanceRegular" android:textSize="@dimen/text_medium" android:background="@android:color/transparent" android:paddingTop="@dimen/margin_14" android:paddingBottom="@dimen/margin_14" android:paddingStart="@dimen/margin_larger" android:paddingEnd="@dimen/margin_zero" />
    <androidx.appcompat.widget.AppCompatEditText android:id="@+id/tagInput" android:layout_width="@dimen/margin_zero" android:layout_height="wrap_content" app:layout_constraintStart_toEndOf="@id/tagPlaceholder" app:layout_constraintTop_toTopOf="@id/tagPlaceholder" app:layout_constraintBottom_toBottomOf="@id/tagPlaceholder" app:layout_constraintEnd_toStartOf="@id/cameraBtn" android:paddingTop="@dimen/margin_14" android:paddingBottom="@dimen/margin_14" android:hint="@string/hint_tag" android:background="@android:color/white" android:textAppearance="@style/BodyAppearanceRegular" android:textSize="@dimen/text_medium" android:textColor="@android:color/black" android:layout_marginStart="@dimen/margin_small"/>
    <androidx.appcompat.widget.AppCompatImageView android:id="@+id/cameraBtn" android:layout_width="@dimen/margin_24" android:layout_height="@dimen/margin_24" android:paddingStart="@dimen/margin_big" android:paddingEnd="@dimen/margin_big" android:paddingTop="@dimen/margin_14" android:paddingBottom="@dimen/margin_14" app:layout_constraintStart_toEndOf="@id/tagInput" app:layout_constraintTop_toTopOf="@id/tagInput" app:layout_constraintBottom_toBottomOf="@id/tagInput" app:layout_constraintEnd_toStartOf="@id/galleryBtn" android:src="@drawable/ic_camera"/>
    <androidx.appcompat.widget.AppCompatImageView android:id="@+id/galleryBtn" android:layout_width="@dimen/margin_24" android:layout_height="@dimen/margin_24" app:layout_constraintEnd_toEndOf="parent" android:paddingStart="@dimen/margin_big" android:paddingEnd="@dimen/margin_larger" android:src="@drawable/ic_gallery" android:paddingTop="@dimen/margin_14" android:paddingBottom="@dimen/margin_14" app:layout_constraintStart_toEndOf="@id/cameraBtn" app:layout_constraintTop_toTopOf="@id/cameraBtn" app:layout_constraintBottom_toBottomOf="@id/cameraBtn" app:layout_constraintHorizontal_chainStyle="packed"/>
</androidx.constraintlayout.widget.ConstraintLayout>

验证效果 #

• 当RecyclerView为GONE时，creatorEditorContainer会紧贴closeButton下方，高度自适应内部内容，不会再居中；
• 点击@图标将RecyclerView设为VISIBLE时，它会自动填充creatorEditorContainer底部到tagPlaceholder顶部的空间，符合弹出扩展的需求。

内容的提问来源于stack exchange，提问作者OK200