Android Java如何在RelativeLayout中填充ı父元素

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- 子元素的布局 -->

</RelativeLayout>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <View
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#FF0000"
        android:layout_alignParentTop="true"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true" />

</RelativeLayout>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:text="Button 1" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="2"
        android:text="Button 2" />

</RelativeLayout>