RecycleView单元格填满屏幕

我正在关注有关android编程的教程，并且遇到了recycleviews的麻烦。每个视图的单元格似乎都占据了整个屏幕空间，而不仅仅是单元格中的信息。如图所示：

activity_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.example.moore.criminalintent.CrimeActivity">


    <include layout="@layout/content_fragment" />


</android.support.design.widget.CoordinatorLayout>

content_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.moore.criminalintent.CrimeActivity"
    tools:showIn="@layout/activity_fragment">

    <FrameLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/fragment_container"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"></FrameLayout>
</RelativeLayout>

fragment_crime.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/Crime_title_label"
        style="?android:listSeparatorTextViewStyle"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/crime_title"
        android:hint="@string/crime_title_hint"/>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_detail_label"
        style="?android:listSeparatorTextViewStyle"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/crime_date"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"/>
    <CheckBox
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/crime_solved"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:text="@string/crime_solved_label"/>
</LinearLayout>

fragment_crime_list.xml

    <?xml version="1.0" encoding="utf-8"?>
    <android.support.v7.widget.RecyclerView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/crime_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

list_item_crime.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/list_item_crime_solved_check_box"
        android:layout_alignParentRight="true"
        android:padding="4dp"/>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/list_item_crime_title_text_view"
        android:layout_toLeftOf="@id/list_item_crime_solved_check_box"
        android:textStyle="bold"
        android:padding="4dp"
        tools:text="Crime Title"/>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/list_item_crime_date_text_view"
        android:layout_toLeftOf="@id/list_item_crime_solved_check_box"
        android:layout_below="@id/list_item_crime_title_text_view"
        android:padding="4dp"
        tools:text="Crime Date"/>

</RelativeLayout>

如果需要，我可以发布更多代码。任何有关如何解决此问题的帮助将不胜感激。