Adjust width of a cardview

Question

I have a problem adjusting the width of a cardview. I have all widths set to "match_parent" but the list of cardviews is displayed like this:[screenshot]

The cardviews are the items of a recyclerview, this is the recyclerview layout code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <include layout="@layout/toolbar"/>
    <Button
        android:id="@+id/escanearCodigo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Escanear codigo"
        android:layout_weight="1"
        />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        />
</LinearLayout>

And this is the code of the items formed by cardviews:

<?xml version="1.0" encoding="utf-8"?>
    <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:layout_height="wrap_content"
        android:layout_margin="12dp"
        android:orientation="vertical">
        <androidx.cardview.widget.CardView
            android:id="@+id/card_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:cardBackgroundColor="#81C784"
            app:cardCornerRadius="9dp"
            app:cardElevation="3dp"
            app:contentPadding="10dp"
            android:layout_margin="5dp"
            >
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <TextView
                    android:id="@+id/idCodigo"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    />

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