JBUtton errors(Cant resolve symbol)

[kimi lynn]

Hello everybody,
I've an interface with couple of buttons which has the functionality to start and stop the matlab engine.The code is working pretty good.So when i press the start,the matlab engine starts and I press stop button to stop the engine.when I press the stop button before pressing the start, I see some errors in my command promtp.I deicided to disable the stop button and declared start and stop button on class level.
Now, I get the errors, cannot resolve symbols at different lines:symbol-variable start and stop.
Could somebody please tell me how can i fix them.
Thanks for your time.

  
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.net.*;
public class MatlabRC
extends javax.swing.JFrame
implements ActionListener
{
private
String StartEng = "Start Matlab-Engine";
String StopEng = "Stop Matlab-Engine";

MatEng engine;
Socket MatlabRCSocket;
DataInputStream in;
DataOutputStream out;
        JButton start = new javax.swing.JButton();
        JButton stop = new javax.swing.JButton();
        boolean remote = false;
JTextField command;
byte[] array;
public MatlabRC()
{
super("Matlab Remote Control");
JPanel cmdPanel = new JPanel();
JPanel onoff = new JPanel();
JPanel getset = new JPanel();
JLabel label = new JLabel (">>");
MatlabRCServer th = new MatlabRCServer();
th.start();
cmdPanel.add (label);
command = new JTextField(50);
command .setToolTipText ("Give a Matlab-Command");
cmdPanel.add(command);
cmdPanel.setBorder (BorderFactory.createEtchedBorder());
getContentPane().add ("North",cmdPanel);
//JButton start = new javax.swing.JButton();
start.setActionCommand(StartEng); 
                onoff.add("Center",start);
start.setIcon(new javax.swing.ImageIcon("F:\\java\\mocha_start.gif"));
//              JButton stop = new javax.swing.JButton();
stop.setActionCommand(StopEng); 
                onoff.add("Center",stop);
stop.setIcon(new javax.swing.ImageIcon("F:\\java\\mocha_quit.gif"));
getContentPane().add("South",getset);
getContentPane().add("Center",onoff);
command.addActionListener(this);
start.addActionListener(this);
stop.addActionListener(this);

addWindowListener(new MainWindowAdapter());
}
public static void main (String[] args)
{
MatlabRC frame = new MatlabRC();
frame.setLocation(100,100);
frame.pack();
frame.setVisible(true);
}
public void actionPerformed (ActionEvent event)
{
try {
if (event.getSource() == StartEng) {
engine = new MatEng();
engine.setOutputBuffer(4096);
                        start.setEnabled(false);
                        stop.setEnabled(true);
return;
}
if (engine != null && event.getSource() == stop){
engine.close();
                        engine = null;
                        start.setEnabled(true);
                        stop.setEnabled(false);
return;
}

[ October 30, 2003: Message edited by: kimi lynn ]

[Ernest Friedman-Hill]

"start" and "stop" are local variables declared in the MatlabRC constructor. That means they're not available to any other methods. They need to be member variables -- i.e., declared at the top level of the class.

[kimi lynn]

Hi there,
Thanks for your response.I corrected them and I dont see any errors now.But unfortunately, I dont see it working how i actually wanted to.
Before, if i press start and then stop it worked and now it does'nt.What exactly, am trying to do is the stop button shld'nt be able to submit by the user with out submitting the start button.
Any ideas??
I edited my code in my previous post.
Thanks for your time.

[Jian Zhang]

well, I can't see the point why you have to declare it as the instance variables first and redefine it again in the constructor. start = new JButton("Start") is enough for the instantiation I think. So any change to it will synchronize. :roll: