How to use jgrapht?

Question

I have a problem using JGraphT to visualize graphs. I use netBeans and I have imported .jar for JGraph and JGraphT and copied everything from JGraphT Visualizations via JGraph and added this code:

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
  JApplet applet = new JApplet();
  applet.init();
  JFrame frame = new JFrame();
  frame.getContentPane().add(applet);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.pack();
  frame.setVisible(true);
} 

but I still get no graph visualization. What should I do to get the graph visualized on a form?