Problem with gettin text from a new window

Question

Hi
I have been trying to for sometime to work out why i cant get this to work...I open a main window which opens a new window when a button is pressed. This window has a text field where data can be typed, it has a button called "Send" which then allows the data to be send. However, when "Send" is pressed, a NullPointerException is throwen in the ActionListener because it is unable to get the text from the text field.
Anyone got any idea why, have done a small mock up just to give an example :
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.event.*;
public class TwoWindows implements ActionListener{
     private JTextField chatLine;
     public volatile boolean start = false;
     //******************************GUI Production******************************
     public TwoWindows() {
          JFrame frame = new JFrame("Multicast Discovery");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          JPanel connectpanel = new JPanel();
          JButton button3 = new JButton("Open New Window");
          button3.setActionCommand("connect");
          button3.addActionListener(this);
          connectpanel.add(button3);
          frame.getContentPane().add(connectpanel, BorderLayout.PAGE_END);
          frame.pack();
          frame.setLocationRelativeTo(null);
          frame.setVisible(true);
     //*****************************action listener******************************
     public void actionPerformed(ActionEvent ae)
          //get what button was pressed
          String button = ae.getActionCommand();
          if (button.equals("search"))
               System.out.println("\n Do Something!");     
          else if (button.equals("cancel"))
               System.out.println("\n Do Something else!");     
          //start new window here
          else if (button.equals("connect"))
               setupChat();
          if (button.equals("send"))
                if (start)
                          //try to get the data from the new window
                          String s = chatLine.getText();
                          System.out.println("This has been inputted : " + s);
     //*****************************setup new window*****************************
     public void setupChat()
          JFrame frame01 = new JFrame("TCP Chat Window");
          frame01.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          // Set up the chat pane
             JPanel chatPane = new JPanel(new BorderLayout());
            JTextArea chatText = new JTextArea(10, 20);
        chatText.setLineWrap(true);
        chatText.setEditable(false);
        chatText.setForeground(Color.blue);
        JScrollPane chatTextPane = new JScrollPane(chatText,
        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
        JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        JTextField chatLine = new JTextField("Type Here!");
        JButton button4 = new JButton("Send");
          button4.setActionCommand("send");
          button4.addActionListener(this);
          chatPane.add(chatLine, BorderLayout.CENTER);
          chatPane.add(button4, BorderLayout.SOUTH);
         chatPane.add(chatTextPane, BorderLayout.NORTH);
          chatPane.setPreferredSize(new Dimension(200, 215));
          frame01.getContentPane().add(chatPane);
          frame01.pack();
          frame01.setLocationRelativeTo(null);
          frame01.setVisible(true);          
          start = true;
     public static void main(String[] args)
     new TwoWindows();
}

Answer 1

public class TwoWindows implements ActionListener{
     private JTextField chatLine;
     public volatile boolean start = false;
     public void setupChat()
JTextField chatLine = new JTextField("Type
ld("Type Here!");
You have two variables called chatLine. One is a class field the other is a local object in setupChat.
Change
JTextField chatLine = new ...
to
chatLine = new ...