### oefening 3 ###

<androidx.constraintlayout.widget.ConstraintLayout...">

    ...
  
    <androidx.gridlayout.widget.GridLayout...>
  
        ...

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ListView"
            android:onClick="startListViewActivity"
            app:layout_row="0"
            app:layout_column="0"
            app:layout_gravity="fill"
            app:layout_columnWeight="1"
            app:layout_rowWeight="1" />
        
        ...
       
    </androidx.gridlayout.widget.GridLayout>
    
    ...

</androidx.constraintlayout.widget.ConstraintLayout>