JButton not working [capture network traffic]

Question

My code which is supposed to capture the network traffic AND display it on textarea but it ain't doing it.Please have a look at the code and check if there is any correction to be made.

public class NewClass {

    public static JTextArea textarea = new JTextArea();

    NewClass() throws IOException{

        JButton capture = new JButton("Capture");
        JFrame frame = new JFrame();        
        JScrollPane scroll;
        NetworkInterface[] NI= JpcapCaptor.getDeviceList();
        int INDEX=0;
        JpcapCaptor JPCAP = JpcapCaptor.openDevice(NI[INDEX], 65536, false, 20);

        frame.setSize(700,500);
        frame.setLocation(200,200);
        frame.getContentPane().setLayout(null);
        frame.setBackground(Color.yellow);        

        textarea.setEditable(false);
        textarea.setFont(new Font("Tahoma",0,14));
        textarea.setForeground(Color.RED);
        textarea.setLineWrap(true);
        //textarea.setBackground(Color.WHITE);

        scroll = new JScrollPane();
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        scroll.setViewportView(textarea);

        frame.getContentPane().add(scroll);
        scroll.setBounds(10,16,740,290);

        capture.setBackground(Color.RED);
        capture.setForeground(Color.GREEN);
        frame.getContentPane().add(capture);

        handler ob = new handler();
        capture.addActionListener(ob);
        capture.setBounds(100, 400, 90, 25);

        frame.setVisible(true);
    }

    public class handler implements ActionListener{
        public void actionPerformed(ActionEvent Event){

            class Print implements PacketReceiver{
                public void receivePacket(Packet packet){
                    String info = packet.toString();
                    textarea.append(info);
                    //System.out.println(packet.toString());
                }                    
            }
    }
}

Answer 1

My code which is supposed to capture the network traffic AND display it on textarea but it ain't doing it.Please have a look at the code and check if there is any correction to be made.

Well for one, your handler's actionPerformed method doesn't really do anything. It defines an inner class but creates no objects of this class and does nothing with it:

public class handler implements ActionListener {
  public void actionPerformed(ActionEvent Event) {
     class Print implements PacketReceiver {
        public void receivePacket(Packet packet) {
           String info = packet.toString();
           textarea.append(info); // System.out.println(packet.toString());
        }
     }
  }
}

Consider creating an object of your Print class (a terrible name for a class since there already is a Print class that is part of the core Java libraries) and having this Print object do something useful, perhaps receive packets (however it's supposed to do that). Be careful not to do long-running processes in the main Swing thread, the EDT though, or you'll freeze your Swing GUI.

Edit
e.g.,

// note that class names such as "Handler" should begin with a capital letter.
public class Handler implements ActionListener {
  public void actionPerformed(ActionEvent Event) {
     class Print implements PacketReceiver {
        public void receivePacket(Packet packet) {
           String info = packet.toString();
           textarea.append(info); // System.out.println(packet.toString());
        }
     }

     // create a Print instance so that it can do something:
     final Print myPrint = new Print();

     // do something with myPrint here so that it gets packets and displays them
     // I suspect that you'll likely want to do this in a background thread
     // using a SwingWorker
  }
}

Answer 2

as Hovercraft said you are doing nothing but defining an inner class. what you are missing here is the call to processPacket() or loopPacket() from your JPCAP class. so what i suggess is the folowing :

public class handler implements ActionListener{
  public void actionPerformed(ActionEvent Event){

    class Print implements PacketReceiver{
        public void receivePacket(Packet packet){
            String info = packet.toString();
            textarea.append(info);                                            
        }

    }

    // this captures 10 packets .
    JPCAP.processPacket(10,new Print());
  }
}