第二次作业

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="#33ffff"
    tools:context="com.example.relativelayout.MainActivity" >
    
     <Button
        android:id="@+id/button1"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:layout_centerInParent="true"
        android:background="#000000" />

     <Button
         android:id="@+id/button2"
         android:layout_width="80dp"
         android:layout_height="80dp"
         android:layout_alignBottom="@id/button1"
         android:layout_toRightOf="@id/button1"
         android:background="#000ccc" />
     
      <Button
         android:id="@+id/button3"
         android:layout_width="80dp"
         android:layout_height="80dp"
         android:layout_alignBottom="@id/button1"
         android:layout_toLeftOf="@id/button1"
         android:background="#336633" />

    <Button
            android:id="@+id/button4"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_above="@+id/button1"
             android:layout_toRightOf="@+id/button3"
             android:background="#ff66ff" />

    <Button
            android:id="@+id/button5"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_above="@+id/button3"
             android:layout_toRightOf="@+id/button4"
             android:background="#ffff00" />
    
    <Button
            android:id="@+id/button6"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_above="@+id/button2"
             android:layout_toLeftOf="@+id/button4"
             android:background="#ffffff"/>
    
    <Button
            android:id="@+id/button7"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_below="@+id/button1"
             android:layout_toRightOf="@+id/button3"
             android:background="#336fcc" />
    
    <Button
            android:id="@+id/button8"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_below="@+id/button1"
             android:layout_toRightOf="@+id/button7"
             android:background="#33ff33" />
    
    <Button
            android:id="@+id/button9"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_below="@+id/button1"
             android:layout_toLeftOf="@+id/button7"
             android:background="#cc0000" />
    
    
      
</RelativeLayout>