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"
    tools:context=".MainActivity" >

    <View
        android:id="@+id/view1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:background="#40E0D0" />

    <Button
        android:id="@+id/Buttondeepgreen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/Buttonblack"
        android:layout_alignBottom="@+id/Buttonblack"
        android:layout_toLeftOf="@+id/Buttonblack"
        android:background="#006400"
        android:minHeight="80dip"
        android:minWidth="80dip" />

    <Button
        android:id="@+id/Buttonblack"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:background="#000000"
        android:minHeight="80dip"
        android:minWidth="80dip" />

    <Button
        android:id="@+id/Buttondeepblue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/Buttonblack"
        android:layout_alignBottom="@+id/Buttonblack"
        android:layout_toRightOf="@+id/Buttonblack"
        android:background="#0000AA"
        android:minHeight="80dip"
        android:minWidth="80dip" />

    <Button
        android:id="@+id/Buttonred"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/Buttondeepgreen"
        android:layout_toLeftOf="@+id/Button