Java Swing - 如何更改JFileChooser中的选定文件以响应事件

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.IOException;

import javax.swing.JFileChooser;

public class Main {
  final static JFileChooser fc = new JFileChooser("/");

  public static void main(String[] args) throws IOException {
    fc.setMultiSelectionEnabled(true);
    fc.addPropertyChangeListener(new ChangeListener());
    fc.showOpenDialog(null);
  }

  private static class ChangeListener implements PropertyChangeListener {
    @Override
    public void propertyChange(PropertyChangeEvent evt) {
      if (JFileChooser.SELECTED_FILES_CHANGED_PROPERTY.equals(evt
          .getPropertyName())) {
        File[] selectedFiles = fc.getSelectedFiles();
        File[] allowedFiles = new File[2];
        if (selectedFiles.length > 2) {
          allowedFiles[0] = selectedFiles[1];
          allowedFiles[1] = selectedFiles[0];
          fc.setSelectedFiles(allowedFiles);
        }
      }
    }
  }
}