title: JFileChooser opens the regular file browser instead of the expanded one
body: <p>Following my previous two posts <a href="https://stackoverflow.com/questions/10907738/use-jfilechooser-without-using-a-main-declaration/10907832#comment14224031_10907832">here</a> and another <a href="https://stackoverflow.com/questions/10900696/how-to-open-files-in-java-swing-without-jfilechooser/10901164#10901164">one here</a>, the following code 
  opens the regular file browser instead of the expanded one:</p>
  
  <pre><code>public class GuiHandler extends javax.swing.JFrame {
      // data members
      private DataParser xmlParser = new DataParser();
      private File newFile;
      JFileChooser jfc = new JFileChooser();
  
      // more code 
  
      public void launchFileChooser() {
          SwingUtilities.invokeLater(new Runnable() {
              @Override
              public void run() {
                  try {
                      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                  } catch(Exception e) {
                      e.printStackTrace();
                  }
                  jfc.setFileSelectionMode(JFileChooser.FILES_ONLY);
                  jfc.setAcceptAllFileFilterUsed(false);
                  if (jfc.showOpenDialog(null) == JFileChooser.APPROVE_OPTION)
                      newFile = jfc.getSelectedFile();
              }
          });
      }
  
      // more code 
  
      private void XMLfilesBrowserActionPerformed(java.awt.event.ActionEvent evt) {       
          launchFileChooser();
          xmlParser.getNodeListFromFile(newFile);
          // here the code has the below problems 
  </code></pre>
  
  <p><strong>Problems:</strong> </p>
  
  <ol>
  <li>The code opens a regular file browser when I hit a button to <code>open XML file</code>; it still allows me to pick a file.</li>
  <li>It throws an exception:</li>
  </ol>
  
  
  
  <pre><code>Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: File cannot be null
      at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:198)
  </code></pre>
  
  <p>Why does it open the regular browser if <code>jfc</code> is a data member, and when it's a local
  variable, the expanded one opens?</p>