title: RadioGroup checkedButton property
body: <p>I am trying to build RadioGroup in Android with one RadioButton checked by default. I'm wondering if this is possible to do through XML, rather than programmatically.</p>
  
  <p>The following code snippet doesn't seem to work as I'm getting an error:</p>
  
  <pre><code>error: Error: No resource found that matches the given name (at 'checkedButton' with value '@id/rdb_positive')
  </code></pre>
  
  <p>The code is:</p>
  
  <pre><code>&lt;RadioGroup
      style="@style/FormInputField"
      android:orientation="vertical"
      android:checkedButton="@id/rdb_positive"&gt; &lt;!-- Error on this line --&gt;
      &lt;RadioButton
          android:id="@+id/rdb_positive"
          android:text="@string/answer_positive" /&gt;
      &lt;RadioButton
          android:id="@+id/rdb_negative"
          android:text="@string/answer_negative" /&gt;
  &lt;/RadioGroup&gt;
  </code></pre>
  
  <p>It does make sense in a way, as the id of the RadioButton is defined after the attribute in the RadioGroup is set, but then I wonder why there is such attribute available.</p>