alignParentBottom makes parent height match parent

Question

Here's the problem parent and it's contents from my xml file:

<RelativeLayout
    android:id="@+id/group_chat_form"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_marginTop="5dp"
    android:background="@drawable/transparent_background2" >

         <TextView 
        android:id="@+id/send_msg_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:background="@drawable/transparent_background2"
        android:text="Send" />

  </RelativeLayout>

The parent is clearly not wrapping the contents.

If I remove the alignParentBottom="true" attribute from the child, it looks perfect.
However I need this particular child to stay anchored to the bottom because I have a multiline edittext view in this same parent (I did not include it since this problem still occurs with the multiline edittext commented out). As the edittext expands with more input from the user, the Send button should stay anchored to the bottom of the parent. Here's what it should look like (multi-lined EditText not included):

Answer 1

That's a limitation for a relative layout. See verified answer in this link

I'm doing the same objective and came up with this solution:

<RelativeLayout
    android:id="@id/comment_input_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:background="@color/light_gray"
    android:padding="4dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:gravity="bottom"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <EditText
            android:id="@id/comment_input_edit_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="@string/label_add_a_comment"
            android:inputType="textCapSentences|textMultiLine"
            android:maxLines="6"
            android:scrollbars="vertical" />

        <Button
            android:id="@id/send_comment_button"
            style="@style/Widget.AppCompat.Button.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/label_send" />

    </LinearLayout>

    <ProgressBar
        android:id="@id/progress_bar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:visibility="gone" />

</RelativeLayout>

the android:layout_weight="1" causes the editText to take up the free space available as long as the other siblings doesn't have weight.

Hope this helps.