On an Android app layout how would I position a view so that it always appears half the distance below the middle?

Question

I'm using a Relative layout as the root or parent container and I have two buttons to place inside this Layout. The buttons need to be placed one on top of the other. The problem is that I want to position these buttons so that they appear below the center of the view but not directly below. That is within the bottom half of the view I want the buttons to appear halfway along that half portion. I tried adding a the buttons as children of a RelativeLayout (that was centered in the middle) inside the parent RelativeLayout and that sort of achieves what I'm trying to but then the Eclipse complains with a warning stating that one set of Relative Layout tags is useless and that I should consider getting rid of it.

Then I tried giving a one of the buttons a top margin with respect to its parent and then placing the other button under the this button with the top margin. This seems to work until I try it out in other virtual devices and I find out that depending on the screen sizes and dimensions it might or might not appear where I want it to (especially not the case with tablet devices).

Ok, so then I'm not sure how to achieve what I want the right way (without warnings or errors). Here's my current code

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/default_real" >

    <Button
        android:id="@+id/sm_panel_email_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="300sp"
        android:background="@drawable/info_view_email_button" />


    <Button
        android:id="@+id/sm_panel_web_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/sm_panel_email_button"
        android:background="@drawable/info_view_web_button" />

</RelativeLayout>

Answer 1

How about using two layouts and the android:layout_weight attribute

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/default_real"
    android:orientation="vertical" >

    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/ >    
    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1" >
        <Button
            android:id="@+id/sm_panel_email_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:background="@drawable/info_view_email_button" />
        <Button
            android:id="@+id/sm_panel_web_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/sm_panel_email_button"
            android:layout_centerHorizontal="true"
            android:background="@drawable/info_view_web_button" />
    </RelativeLayout>

</LinearLayout>