activity_control.xml

<RelativeLayout 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"
    tools:context="com.godoro.androiddevices.ControlActivity">


    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/startService"
        android:id="@+id/startServiceButton"
        android:layout_alignParentTop="true"
        android:layout_alignRight="@+id/stopServiceButton"
        android:layout_alignEnd="@+id/stopServiceButton"
        android:layout_marginTop="47dp"
        android:onClick="onServiceStartClick"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/stopService"
        android:id="@+id/stopServiceButton"
        android:layout_below="@+id/startServiceButton"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="79dp"
        android:onClick="onServiceStopClick"/>
</RelativeLayout>