Newbie : Using "this" in a function

Question

I have a function in my main class that spawns
a Dialog for user input. The strange thing is, that I get
a compiler error anytime i try to use "this" inside my
function. Please help. Can you see anything wrong
with the code in this function? I am calling it from
another class.
public static void createNewCell() {
JDialog newDialog = new JDialog();
newDialog.setTitle("New Cell Site");
newDialog.setResizable(false);
newDialog.setModal(true);
//create txt fields
CDBTextField txtCellID = new CDBTextField(15,10);
//create buttons
JButton btnOK = new JButton("OK");
btnOK.setActionCommand("ok");
btnOK.addActionListener(this);
JButton btnCancel = new JButton("Cancel");
btnCancel.setActionCommand("cancel");
btnCancel.addActionListener(this);
//Layout the labels in a panel
JPanel labelPane = new JPanel();
labelPane.setLayout(new GridLayout(0, 1));
labelPane.add(new JLabel("Cell ID:"));
//Layout the text fields in a panel
JPanel fieldPane = new JPanel();
fieldPane.setLayout(new GridLayout(0, 1));
fieldPane.add(txtCellID);
//Layout the buttons in a panel
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new GridLayout(0, 2));
buttonPane.add(btnCancel);
buttonPane.add(btnOK);
//Put the panels in another panel, labels on left,
//text fields on right
JPanel contentPane = new JPanel();
contentPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
contentPane.setLayout(new BorderLayout(10,10));
contentPane.add(labelPane, BorderLayout.CENTER);
contentPane.add(fieldPane, BorderLayout.EAST);
contentPane.add(buttonPane, BorderLayout.SOUTH);
newDialog.setContentPane(contentPane);
newDialog.pack();
newDialog.show();
Here is the compiler message
CDBTest.java:152: non-static variable this cannot be referenced from a static co
ntext
btnOK.addActionListener(this);
^
CDBTest.java:155: non-static variable this cannot be referenced from a static co
ntext
btnCancel.addActionListener(this);
^
2 errors
I guess I don't really understand how to use static and
when not to use static, and how to use "this"
But I know I need to use "this" for the actionlisteners
on my buttons.
THanks
Josh

Answer 1

Thank you , Thank you, Thank you!
Here is my entire main class, and then below it I'll
paste the class that is calling my function.
import java.io.*;
import java.util.StringTokenizer;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.ArrayList;
public class CDBTest extends JFrame implements ActionListener {
        public static CellList cellList = new CellList();
        public static Tabs cdbTabs = new Tabs();
        public static ArrayList cellArrayList = new ArrayList();
        public static int internalCellId = 0;    
        public CDBTest() {
                JMenuBar mainMenuBar = new JMenuBar();
                JMenu mainMenu;
                JMenuItem mainMenuItem;
                JPanel mainPanel = new JPanel();
                //Attach Menu Bar
                setJMenuBar(mainMenuBar);
                //Build the first menu.
                mainMenu = new JMenu("File");
                mainMenu.setMnemonic(KeyEvent.VK_F);
                mainMenuBar.add(mainMenu);
                //JMenuItems
                mainMenuItem = new JMenuItem("New",KeyEvent.VK_N);
                mainMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N, ActionEvent.CTRL_MASK));
                mainMenuItem.addActionListener(this);
                mainMenu.add(mainMenuItem);
                mainMenuItem = new JMenuItem("Open",KeyEvent.VK_O);
                mainMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, ActionEvent.CTRL_MASK));
                mainMenuItem.addActionListener(this);
                mainMenu.add(mainMenuItem);
                mainMenu.addSeparator();
                mainMenuItem = new JMenuItem("Save",KeyEvent.VK_S);
                mainMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, ActionEvent.CTRL_MASK));
                mainMenuItem.addActionListener(this);
                mainMenu.add(mainMenuItem);
                mainMenuItem = new JMenuItem("Save As",KeyEvent.VK_A);
                mainMenuItem.addActionListener(this);
                mainMenu.add(mainMenuItem);
                mainMenu.addSeparator();
                mainMenuItem = new JMenuItem("Exit",KeyEvent.VK_E);
                mainMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F4, ActionEvent.ALT_MASK));
                mainMenuItem.addActionListener(this);
                mainMenu.add(mainMenuItem);
                //define main content panel
                mainPanel.setPreferredSize(new Dimension(600, 350));
                //Turn border off for now 3/19/02
                //mainPanel.setBorder(BorderFactory.createLineBorder(Color.black));
                setResizable(false);
                setTitle("Cell Site Database Editor");
                //define and add components
                mainPanel.add(cellList);
                mainPanel.add(cdbTabs);
                setContentPane(mainPanel);
        public void actionPerformed(ActionEvent e) {
                JMenuItem source = (JMenuItem)(e.getSource());
                if (source.getText() == "Open") {
                        // "." represents current dir, NOT APP-DIR,
                        // AND worse, the "Up" feature in filechooser now broken
                        // DAMNIT!
                        //final JFileChooser fc = new JFileChooser(".");
                        final JFileChooser fc = new JFileChooser();
                        fc.addChoosableFileFilter(new CDBFileFilter());
                        int returnVal = fc.showOpenDialog(this);
                        if (returnVal == JFileChooser.APPROVE_OPTION) {
                                File file = fc.getSelectedFile();
                                //this is where a real application would open the file.
                                //JOptionPane.showMessageDialog(this, "Opening " + file.getName());
                                try {
                                        // Clear out any existing entries
                                        if (cellList.isFilled()) {
                                                cellArrayList.clear();
                                                cellList.removeAllFromJList();
                                                internalCellId = 0;
                                        FileReader cdbReader = new FileReader(file);
                                        BufferedReader br = new BufferedReader(cdbReader);
                                        //JComboBox cellList = new JComboBox();
                                        //cellList.addActionListener(this);
                                        String line;
                                        while((line = br.readLine()) != null){
                                                // Looping through each line
                                                cellArrayList.add(internalCellId, Split(line,",")); //Add array with an index
                                                String[] arCells = (String[]) cellArrayList.get(internalCellId); //Extract array object and cast as a String Array
                                                cellList.AddCell(arCells[0] + " " + arCells[1]);
                                                //cellList.addItem(arCells[0] + " " + arCells[1]);
                                                internalCellId++;
                                        cellList.list.setSelectedIndex(0);
                                } catch (FileNotFoundException fnf) {
                                        System.err.println("Unable to open file for reading: " + fnf.getMessage());
                                } catch (IOException ioe) {
                                        System.err.println("unable to buffer read file: " + ioe.getMessage());
                        } else {
                                JOptionPane.showMessageDialog(this, "Cancelled ");
                } else if (source.getText() == "Exit") {
                        System.exit(0);
                } else {
                        String s = "Action event detected.\n"
                           + "    Event source: " + source.getText()
                           + " (an instance of " + getClassName(source) + ")";
                        JOptionPane.showMessageDialog(this, s);
        public static String[ ] Split(String str2Split, String separator) {
                StringTokenizer parser = new StringTokenizer(str2Split, separator);
                int numTokens=parser.countTokens( );
                String[ ] arString = new String[numTokens];
                for (int i=0; i < numTokens; i++) {
                        arString[i] = parser.nextToken( );
                return arString;
        public void createNewCell() {
                JDialog newDialog = new JDialog();
                newDialog.setTitle("New Cell Site");
                newDialog.setResizable(false);
                newDialog.setModal(true);
                //create txt fields
                CDBTextField txtCellID = new CDBTextField(15,10);
                CDBTextField txtCellName = new CDBTextField(15,20);
                CDBTextField txtSwitch = new CDBTextField(15,10);
                CDBTextField txtSectorID = new CDBTextField(1,1);
                CDBTextField txtSectorName = new CDBTextField(15,12);
                //create buttons
                JButton btnOK = new JButton("OK");
                btnOK.setActionCommand("ok");
                btnOK.addActionListener(this);
                JButton btnCancel = new JButton("Cancel");
                btnCancel.setActionCommand("cancel");
                btnCancel.addActionListener(this);
                //Layout the labels in a panel
                JPanel labelPane = new JPanel();
                labelPane.setLayout(new GridLayout(0, 1));
                labelPane.add(new JLabel("Cell ID:"));
                labelPane.add(new JLabel("Cell Name:"));
                labelPane.add(new JLabel("Switch:"));
                labelPane.add(new JLabel("Sector ID:"));
                labelPane.add(new JLabel("Sector Name:"));
                //Layout the text fields in a panel
                JPanel fieldPane = new JPanel();
                fieldPane.setLayout(new GridLayout(0, 1));
                fieldPane.add(txtCellID);
                fieldPane.add(txtCellName);
                fieldPane.add(txtSwitch);
                fieldPane.add(txtSectorID);
                fieldPane.add(txtSectorName);
                //Layout the buttons in a panel
                JPanel buttonPane = new JPanel();
                buttonPane.setLayout(new GridLayout(0, 2));
                buttonPane.add(btnCancel);
                buttonPane.add(btnOK);
                //Put the panels in another panel, labels on left,
                //text fields on right
                JPanel contentPane = new JPanel();
                contentPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
                contentPane.setLayout(new BorderLayout(10,10));
                contentPane.add(labelPane, BorderLayout.CENTER);
                contentPane.add(fieldPane, BorderLayout.EAST);
                contentPane.add(buttonPane, BorderLayout.SOUTH);
                newDialog.setContentPane(contentPane);
                newDialog.pack();
                newDialog.show();      
        // Returns just the class name -- no package info.
        protected String getClassName(Object o) {
                String classString = o.getClass().getName();
                int dotIndex = classString.lastIndexOf(".");
                return classString.substring(dotIndex+1);
        public static void main(String args[]) {
                final CDBTest CDBApp = new CDBTest();
                CDBApp.addWindowListener(new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                CDBApp.pack();
                CDBApp.show();
I'm new to Java and trying tio pick it up as I code
so please give me any recommendations you have
some things I don't really understand.
And here is the code of my class that calls the function
in my main class.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ActionButtons extends JPanel implements ActionListener {
        protected JButton btnNew, btnCopy, btnDelete;
        private int btnWidth = 35;
        private int btnHeight = 34;
        public ActionButtons() {
                ImageIcon icoBtnNew = new ImageIcon("images/new.gif");
                ImageIcon icoBtnCopy = new ImageIcon("images/copy.gif");
                ImageIcon icoBtnDelete = new ImageIcon("images/delete.gif");
                btnNew = new JButton(icoBtnNew);
                btnNew.setPreferredSize(new Dimension(btnWidth,btnHeight));
                btnNew.setToolTipText("Create a new cell site.");
                btnNew.setActionCommand("new");
                btnNew.addActionListener(this);
                add(btnNew);
                btnCopy = new JButton(icoBtnCopy);
                btnCopy.setPreferredSize(new Dimension(btnWidth,btnHeight));
                btnCopy.setToolTipText("Copy selected cell site.");
                btnCopy.setActionCommand("copy");
                btnCopy.addActionListener(this);
                add(btnCopy);
                btnDelete = new JButton(icoBtnDelete);
                btnDelete.setPreferredSize(new Dimension(btnWidth,btnHeight));
                btnDelete.setToolTipText("Delete selected cell site.");
                btnDelete.setActionCommand("delete");
                btnDelete.addActionListener(this);
                add(btnDelete);
       public void actionPerformed(ActionEvent e) {
                if (e.getActionCommand() == "new") {
                        //switch tabs to general tab
                        CDBTest.createNewCell();
Thanks
Josh