Android RecyclerView网格布局菜单不对齐，求正确修复方案

我遇到了RecyclerView菜单项不对齐的问题，相关代码如下：

布局文件 #

RecyclerLayout.xml #

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="match_parent"
    android:background="#FF00FF">  

   <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/Recyclergrid"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        app:cardBackgroundColor="@color/app_background"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/Boxlayout" />
</LinearLayout>

CardLayout.xml #

<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="wrap_content"
    android:layout_height="wrap_content"
    android:clipToPadding="false"
    android:layout_gravity="center"
    android:foreground="?selectableItemBackgroundBorderless"
    android:layout_marginBottom="20dp"
    android:id="@+id/root">

    <androidx.cardview.widget.CardView
        android:id="@+id/CardLayout"
        android:layout_width="100dp"
        android:layout_height="150dp"
        app:cardCornerRadius="4dp"
        app:cardElevation="0dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@id/TextView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/idIVcourseIV"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop" />
    </androidx.cardview.widget.CardView>

    <TextView
        android:id="@+id/TextView"
        android:layout_width="0dp"
        android:fontFamily="sans-serif"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:minLines="2"
        android:maxLines="2"
        android:layout_marginTop="4dp"
        android:textColor="#FFFFFF"  
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Java 逻辑代码 #

Rcv= findViewById(R.id.Recyclergrid ); 
CardArray= new ArrayList<>();  
CardArray.add(new DataModel("Text" ,"Title"));
RecyclerAdapter RcvAdapter= new RecyclerAdapter(this, CardArray);
Rcv.setLayoutManager(new GridLayoutManager(this, 3));
Rcv.setAdapter(RcvAdapter); 

我尝试给RecyclerView添加gravity="center"属性未生效，目前通过给CardView加padding、居中RecyclerView的方式临时适配，求正确的修复方案。

• 核心修改：调整CardLayout.xml根布局的宽度属性，将android:layout_width="wrap_content"改为android:layout_width="match_parent"。GridLayoutManager会自动给每个item分配屏幕宽度1/3的可用区域，根布局占满分配区域后，内部已经配置了双向约束的CardView和TextView会自动在item区域内居中，自然解决对齐问题。
• 可选优化：如果需要统一调整item之间的上下左右间距，可给RecyclerView添加自定义ItemDecoration，示例实现如下：

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
    private int spanCount;
    private int spacing;
    private boolean includeEdge;

    public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
        this.spanCount = spanCount;
        this.spacing = spacing;
        this.includeEdge = includeEdge;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view);
        int column = position % spanCount;
        if (includeEdge) {
            outRect.left = spacing - column * spacing / spanCount;
            outRect.right = (column + 1) * spacing / spanCount;
            if (position < spanCount) {
                outRect.top = spacing;
            }
            outRect.bottom = spacing;
        } else {
            outRect.left = column * spacing / spanCount;
            outRect.right = spacing - (column + 1) * spacing / spanCount;
            if (position >= spanCount) {
                outRect.top = spacing;
            }
        }
    }
}

使用时在设置LayoutManager之后添加即可：

// 可提前在dimens.xml中定义间距值，单位dp
int spacing = getResources().getDimensionPixelSize(R.dimen.grid_spacing);
Rcv.addItemDecoration(new GridSpacingItemDecoration(3, spacing, true));

内容的提问来源于stack exchange，提问作者yamete senpai