activity_main.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" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true">

        <ImageView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_column="0"
            android:layout_row="0"
            android:layout_gravity="fill"
            android:id="@+id/imageView" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_row="1"
            android:layout_column="0"
            android:tag="0"
            android:text=""
            android:id="@+id/button"
            android:onClick="celebChosen" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_row="2"
            android:layout_column="0"
            android:tag="1"
            android:text=""
            android:id="@+id/button2"
            android:onClick="celebChosen" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_row="3"
            android:layout_column="0"
            android:tag="2"
            android:text=""
            android:id="@+id/button3"
            android:onClick="celebChosen" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_row="4"
            android:layout_column="0"
            android:tag="3"
            android:text=""
            android:id="@+id/button4"
            android:onClick="celebChosen" />
    </GridLayout>
</RelativeLayout>