Error with my simple GUI code

[Menre]

Hi,

I was just going trough a simple Java GUI tutorial when I ran into trouble. I get an error message cannot find symbol and it makes reference to line 56, which is this line below.

f.addWindowListener(new ListenCloseWdw());

I have pasted the complete code below for help please.

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class BasicGui {
	private JFrame f = new JFrame("Basic GUI");
	private JPanel pnlNorth = new JPanel(); //North area
	private JPanel pnlSouth = new JPanel(); //South area
	private JPanel pnlEast  = new JPanel(); //East area
	private JPanel pnlWest = new JPanel(); //West area
	private JPanel pnlCenter = new JPanel(); //Center area
	
	//A few buttons to put in the panels
	private JButton btnNorth = new JButton("North");
	private JButton btnSouth = new JButton("South");
	private JButton btnEast = new JButton("East");
	private JButton btnWest = new JButton("West");
	private JButton btnCenter = new JButton("Center");
	
	//here we put some menus
	private JMenuBar mb = new JMenuBar(); //Menubar
	private JMenu mnuFile = new JMenu("File"); // File entry on menu bar
	private JMenuItem mnuItemQuit = new JMenuItem("Quit"); //quite sub item
	private JMenu mnuHelp = new JMenu("Help"); //help menu entry
	private JMenuItem mnuItemAbout = new JMenuItem("About"); //about entry
	
	/*here we have a construtor for the GUI*/
	  public BasicGui() {
	  	// Set menu bar
	  	f.setJMenuBar(mb);
	  	
	  	//Build Menus
	  	mnuFile.add(mnuItemQuit); // Create quit line
	  	mnuHelp.add(mnuItemAbout); //Create About line
	  	mb.add(mnuFile); // Add menu items to form
	  	mb.add(mnuHelp);
	  	
	  	// Add Buttons
	  	pnlNorth.add(btnNorth);
	  	pnlSouth.add(btnSouth);
	  	pnlEast.add(btnEast);
	  	pnlWest.add(btnWest);
	  	pnlCenter.add(btnCenter);
	  	
	  	// Setup Main Frame
	  	f.getContentPane().setLayout(new BorderLayout());
	  	f.getContentPane().add(pnlNorth, BorderLayout.NORTH);
	  	f.getContentPane().add(pnlSouth, BorderLayout.SOUTH);
	  	f.getContentPane().add(pnlEast,  BorderLayout.EAST);
	  	f.getContentPane().add(pnlWest,  BorderLayout.WEST);
	  	f.getContentPane().add(pnlCenter, BorderLayout.CENTER);
	  	
	  	//Allows the swing App to be closed
	  	f.addWindowListener(new ListenCloseWdw());
	  	
	  	//Add Menu listener
	  	mnuItemQuit.addActionListener(new ListenMenuQuit());
	  }
	  
	  //Add menu listenet
	  public class ListenMenuQuit implements ActionListener{
	  	  public void actionPerformed(ActionEvent e){
	  	  	System.exit(0);
	  }
	}
	  
	  public class ListenCloseWindowAdapter{
	  	 public void windowClosing(WindowEvent e) {
	  	 	System.exit(0);
	  	 }
	  }

  public void launchFrame(){
  	//Display Frame
  	f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  	f.pack(); //Adjust panel to component for display
  	f.setVisible(true);
  }
  
  public static void main(String [] args) {
  	BasicGui gui = new BasicGui();
  	gui.launchFrame();
  }
}

[Norm]

Please post the full text of the error message when you get errors.
Which symbol can't it find?

[JosAH]

There simply is no ListenCloseWdw class in scope; that's why your compiler is whining.

kind regards,

Jos

[Fubarable]

Where is the code for the ListenCloseWdw class?

[Menre]

Hi Again,
The full error message that I am getting is shown below.

cannot find symbol class ListenCloseWdw

There simply is no ListenCloseWdw class in scope; that's why your compiler is whining.

Where is the code for the ListenCloseWdw class?

The code that I posted earlier is the full code that I read in the tutorial. I thought as much that something was missing or not right with that tutorial. I have not been able to fix it now. Can someone help me sove the problem, please?

[Norm]

What you posted is NOT the full text of the error message. You've only given part of it.
Here is an example of the full text:

TabbedPaneDemo.java:162: cannot find symbol
symbol : class NoClassDef
location: class TabbedPaneDemo
new NoClassDef();
^

I think the class you need(ListenCloseWindowAdapter) is defined in your source but spelled differently:
Replace ListenCloseWdw() with ListenCloseWindowAdapter()
to use the class that is in your source.

Also you need to add: extends WindowAdapter after 'public class ListenCloseWindowAdapter()'

[Menre]

Thank you very much everyone. I did as you said and it is now working perfectly. The corrected code is place below.

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class BasicGui {
	private JFrame f = new JFrame("Basic GUI");
	private JPanel pnlNorth = new JPanel(); //North area
	private JPanel pnlSouth = new JPanel(); //South area
	private JPanel pnlEast  = new JPanel(); //East area
	private JPanel pnlWest = new JPanel(); //West area
	private JPanel pnlCenter = new JPanel(); //Center area
	
	//A few buttons to put in the panels
	private JButton btnNorth = new JButton("North");
	private JButton btnSouth = new JButton("South");
	private JButton btnEast = new JButton("East");
	private JButton btnWest = new JButton("West");
	private JButton btnCenter = new JButton("Center");
	
	//here we put some menus
	private JMenuBar mb = new JMenuBar(); //Menubar
	private JMenu mnuFile = new JMenu("File"); // File entry on menu bar
	private JMenuItem mnuItemQuit = new JMenuItem("Quit"); //quite sub item
	private JMenu mnuHelp = new JMenu("Help"); //help menu entry
	private JMenuItem mnuItemAbout = new JMenuItem("About"); //about entry
	
	/*here we have a construtor for the GUI*/
	  public BasicGui() {
	  	// Set menu bar
	  	f.setJMenuBar(mb);
	  	
	  	//Build Menus
	  	mnuFile.add(mnuItemQuit); // Create quit line
	  	mnuHelp.add(mnuItemAbout); //Create About line
	  	mb.add(mnuFile); // Add menu items to form
	  	mb.add(mnuHelp);
	  	
	  	// Add Buttons
	  	pnlNorth.add(btnNorth);
	  	pnlSouth.add(btnSouth);
	  	pnlEast.add(btnEast);
	  	pnlWest.add(btnWest);
	  	pnlCenter.add(btnCenter);
	  	
	  	// Setup Main Frame
	  	f.getContentPane().setLayout(new BorderLayout());
	  	f.getContentPane().add(pnlNorth, BorderLayout.NORTH);
	  	f.getContentPane().add(pnlSouth, BorderLayout.SOUTH);
	  	f.getContentPane().add(pnlEast,  BorderLayout.EAST);
	  	f.getContentPane().add(pnlWest,  BorderLayout.WEST);
	  	f.getContentPane().add(pnlCenter, BorderLayout.CENTER);
	  	
	  	//Allows the swing App to be closed
	  	f.addWindowListener(new ListenCloseWindowAdapter());
	  	
	  	//Add Menu listener
	  	mnuItemQuit.addActionListener(new ListenMenuQuit());
	  }
	  
	  //Add menu listenet
	  public class ListenMenuQuit implements ActionListener{
	  	  public void actionPerformed(ActionEvent e){
	  	  	System.exit(0);
	  }
	}
	  
	  public class ListenCloseWindowAdapter extends WindowAdapter{
	  	 public void windowClosing(WindowEvent e) {
	  	 	System.exit(0);
	  	 }
	  }

  public void launchFrame(){
  	//Display Frame
  	f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  	f.pack(); //Adjust panel to component for display
  	f.setVisible(true);
  }
  
  public static void main(String [] args) {
  	BasicGui gui = new BasicGui();
  	gui.launchFrame();
  }
}

Once again, thanks.