title: setBackgroundResource calls android.content.res.Resources$NotFoundException
body: <p>I have <code>btn_solve_selector.xml</code> file in Drawable folder in order to set <code>Button</code> background programatically.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  &lt;item android:state_pressed="true"
        android:color="#ffff0000"/&gt; &lt;!-- pressed --&gt;
  &lt;item android:state_focused="true"
        android:color="#ff0000ff"/&gt; &lt;!-- focused --&gt;
  &lt;item android:color="#ff0000ff"/&gt; &lt;!-- default --&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p>With above code, I coded below code in <code>onCreate</code> of <code>MyActivity</code>.</p>
  
  <pre><code>    _button1.setBackgroundResource(R.drawable.btn_solve_selector);
  </code></pre>
  
  <p>But the app was crashed with followed stacktrace.</p>
  
  <pre><code>Caused by: android.content.res.Resources$NotFoundException: File res/drawable/btn_solvenow_selector.xml from drawable resource ID #0x7f020085
  ....
  at com.MyPackage.MyActivity.setMode(MyActivity.java:343)
  ....
  Caused by: org.xmlpull.v1.XmlPullParserException: Binary XML file line #4: &lt;item&gt; tag requires a 'drawable' attribute or child tag defining a drawable
  ....
  </code></pre>
  
  <p>It seems like the drawable xml file is failed to read even the file has <code>&lt;item /&gt;</code> inside of it and then fall-back to read android.content.res as a second trial. (I even checked with <code>com.MyPackage.R.drawable.btn_solve_selector</code> instead but failed).</p>
  
  <p>I removed and reinstalled the app but failed. What am I missing?</p>