res/layout/activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    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"
    tools:context=".MainActivity" >

<Button
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_weight="1"
        android:text="@string/EPM_ON"
        android:onClick="EpmOn" />

<Button
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_weight="1"
        android:text="@string/EPM_OFF"
        android:onClick="EpmOff" />

</LinearLayout>