Multiple Screen Design on Android

Question

I want to design some android layout for multiple screen resolution. Forexample I want to set position for button. It must be set positioned at the bottom of layout for every screen size. How can I design it ? Thanks for attention.

<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"
    android:background="@drawable/arayuz" >

    <Spinner
        android:id="@+id/spinner1"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp" />

    <Spinner
        android:id="@+id/spinner2"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/spinner1"
        android:layout_below="@+id/spinner1"
        android:layout_marginTop="25dp" />

    <Spinner
        android:id="@+id/spinner3"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/spinner2"
        android:layout_below="@+id/spinner2"
        android:layout_marginTop="25dp" />

    <Spinner
        android:id="@+id/spinner4"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/spinner3"
        android:layout_below="@+id/spinner3"
        android:layout_marginTop="25dp" />

    <Button
        android:id="@+id/button1"
        android:layout_width="100dp"
        android:layout_height="40dp"
        android:layout_below="@+id/spinner4"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="25dp"
        android:background="@drawable/custom_button"
        android:text="@string/ara"
        android:textColor="#efefef"
        android:textSize="18dp" />
</RelativeLayout>

Answer 1

just use android:layout_alignParentBottom and android:layout_centerHorizontal for the button, it will be shown centered bottom of the screen

   <Button
        android:id="@+id/button1"
        android:layout_width="100dp"
        android:layout_height="40dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="25dp"
        android:text="asdad"
        android:textColor="#efefef"
        android:textSize="18dp" />