title: How to create ripple effect in simple layout
body: <p>How can I have a ripple effect in a simple linear/relative layout when touching the layout?</p>
  
  <p>I've tried setting the background of a layout to something like:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;ripple xmlns:android="http://schemas.android.com/apk/res/android"
      android:color="?android:colorControlHighlight" &gt;
  
      &lt;item android:drawable="@android:color/white"/&gt;
  
  &lt;/ripple&gt;
  </code></pre>
  
  <p>However I'm only seeing a plain white background and no ripple effect when touching the layout.  What am I doing wrong?</p>
  
  <p>Edit:</p>
  
  <p>For reference, here is my layout xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="250dp"
          android:layout_height="250dp"
          android:background="@drawable/test"
          android:clickable="true"&gt;
      &lt;/RelativeLayout&gt;
  </code></pre>