1.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"
android:layout_height="match_parent">

<Button
android:id="@+id/button1"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#673AB7"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button2"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#8BC34A"
android:layout_toLeftOf="@id/button1"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button3"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#8BC34A"
android:layout_toRightOf="@id/button1"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button4"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#2196F3"
android:layout_above="@id/button1"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button5"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#9C27B0"
android:layout_toLeftOf="@+id/button4"
android:layout_above="@id/button2"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button6"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#9C27B0"
android:layout_toRightOf="@+id/button4"
android:layout_above="@id/button3"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button7"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#2196F3"
android:layout_below="@id/button1"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button8"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#9C27B0"
android:layout_below="@id/button2"
android:layout_toLeftOf="@id/button7"
android:layout_centerInParent="true"
android:text=""
/>
<Button
android:id="@+id/button9"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#9C27B0"
android:layout_toRightOf="@+id/button4"
android:layout_below="@id/button3"
android:layout_centerInParent="true"
android:text=""
/>


</RelativeLayout>