I use GLJPanel and I write below code but I have below error But I do not take any error GLcanvas. I think I take error when I call getContext() method. How can I solve this problem
            Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.media.opengl.GLJPanel.getContext(GLJPanel.java:787)
at FisrtJoglPackage.SceneRenderer.<init>(JOGLDemo5.java:221)
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public class JOGLDemo5 extends JFrame implements ChangeListener
{
final static int WIDTH = 100;
final static int HEIGHT = 100;
final static int FPS = 30;
private SceneRenderer sr;
FPSAnimator animator;
public JOGLDemo5 ()
{
  super ("JOGLDemo #5");
 
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  GLCapabilities caps=new GLCapabilities();
  caps.setAlphaBits(0);
   sr = new SceneRenderer (caps);
  
  final Animator animator = new Animator(sr);
  sr.setPreferredSize (new Dimension (WIDTH, HEIGHT));
 this.add(sr);
   
 
  initGui();
       
  pack ();
  setVisible (true);
  animator.start();
}
public static void main (String [] args)
{
Runnable r = new Runnable ()
{
public void run ()
{
new JOGLDemo5 ();
                   }
               };
  EventQueue.invokeLater (r);
}
class SceneRenderer extends GLJPanel implements GLEventListener,MouseListener,MouseMotionListener
{
public SceneRenderer ( GLCapabilities caps)
{
  super(caps);
  GLContext context=  this.getContext();
   context.getGL();
   addGLEventListener (this);
}
public void init (GLAutoDrawable drawable)
{
  GL gl = drawable.getGL ();
  glc=drawable.getGL();
  gl.glEnable (GL.GL_DEPTH_TEST);
  gl.glShadeModel(GL.GL_SMOOTH);
  gl.glClearColor(0, 0, 0, 0);
}
public void display (GLAutoDrawable drawable)
{
  GL gl = drawable.getGL ();
    //Draw Something
}
public void reshape (GLAutoDrawable drawable, int x, int y, int width,
int height)
{
}
