如何删除cardview和button之间的空格

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="0dp">

        <!-- CardView的内容 -->

    </androidx.cardview.widget.CardView>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />

</LinearLayout>

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <androidx.cardview.widget.CardView
        android:id="@+id/cardView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <!-- CardView的内容 -->

    </androidx.cardview.widget.CardView>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        app:layout_constraintStart_toStartOf="@id/cardView"
        app:layout_constraintTop_toBottomOf="@id/cardView" />

</androidx.constraintlayout.widget.ConstraintLayout>

<androidx.recyclerview.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" />

// 在代码中设置RecyclerView的布局管理器和适配器
RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(adapter);