title: What is the different between the folder "drawable" and the file "drawable.xml"?
body: <p>In the activity_main.xml, there are two rows code <code>android:background="@drawable/border_ui"</code> and <code>android:background="@drawable/my",</code>  </p>
  
  <p>but the one use the border_ui.xml located the folder res\drawable, and the other use the file drawable.xml located the folder res\values. </p>
  
  <p>What different? Thanks!  </p>
  
  <p>And more, an error will occur if I remove the file drawable.xml to the folder res\drawable and rename it as my.xml.</p>
  
  <p>activity_main.xml</p>
  
  <pre><code>&lt;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" 
      android:background="@drawable/border_ui"
      &gt;
  
      &lt;TextView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/hello_world" 
          android:background="@drawable/my"
          /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>border_ui.xml</p>
  
  <pre><code>&lt;shape xmlns:android="http://schemas.android.com/apk/res/android" &gt;   
      &lt;stroke android:width="1dp" android:color="#000000" /&gt;     
      &lt;solid android:color="#ffffff" /&gt;
      &lt;padding
          android:bottom="1dp"
          android:left="1dp"
          android:right="1dp"
          android:top="1dp" /&gt;
  
  &lt;/shape&gt;
  </code></pre>
  
  <p>drawable.xml</p>
  
  <pre><code>&lt;resources&gt;
    &lt;drawable name="my"&gt;#f00&lt;/drawable&gt;
  &lt;/resources&gt;
  </code></pre>