解决 No resource found that matches the given name (at 'layout_above' with value '@id/button3'）.

今天继续学习郭少的<<第一行代码>>，读到3.3.2相对布局这一章（P102页），根据书上的实例，运行以后在控制台显示了，

Information:Gradle tasks [:app:assembleDebug]
C:\Users\Administrator\AndroidStudioProjects\UILayoutTest\app\src\main\res\layout\activity_main.xml
Error:(10, 31) No resource found that matches the given name (at 'layout_above' with value '@id/button3').
Error:(11, 34) No resource found that matches the given name (at 'layout_toLeftOf' with value '@id/button3').
Error:(17, 31) No resource found that matches the given name (at 'layout_above' with value '@id/button3').
Error:(18, 35) No resource found that matches the given name (at 'layout_toRightOf' with value '@id/button3').

好你是说没有找到与‘@id/button3‘匹配的名字的资源，怎么回事呢，仔细看了一下activity_main.xml，发现了问题

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@id/button3"
    android:layout_toLeftOf="@id/button3"
    android:text="Button 1" />
<Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@id/button3"
    android:layout_toRightOf="@id/button3"
    android:text="Button 2" />

<Button
    android:id="@+id/button3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="Button 3" />

<Button
    android:id="@+id/button4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/button3"
    android:layout_toLeftOf="@id/button3"
    android:text="Button 4" />
<Button
    android:id="@+id/button5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/button3"
    android:layout_toRightOf="@id/button3"
    android:text="Button 5" />

最后读到第103页，上面清楚的写到。注意，当一个控件去引用另一个控件的id时，该控件一定要定义在引用控件的后面，不然会出现找不到id的情况。将button3写到中间了，将button3的位置放到button1上面就行了，期待大家不要犯同样的错误！