title: LinearLayout findViewById problem - crash
body: <p>my problem is probably pretty simple. 
  I have defined a LinearLayout in my layout.xml file and want to set the background drawable in code. </p>
  
  <p>layout.xml</p>
  
  <pre><code>&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/linlay"
  android:orientation="vertical"
  android:layout_width="fill_parent"&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>.java</p>
  
  <pre><code>public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      LinearLayout ln = (LinearLayout) this.findViewById(R.id.linlay);
      setContentView(ln);
      ln.setBackgroundDrawable(getResources().getDrawable(R.drawable.wallpaper));
  }
  </code></pre>
  
  <p>If I run the app it says the application has stopped unexpectedly. 
  any ideas? </p>