JDialog unknown compiler error?

Question

Hello,
I wrote this basic code to learn the use of JDialogs, the problem is when I tried to add the model and title to the Dialog class constructor, I got this compiler error:
TestGUI.java:24: cannot resolve symbol
symbol : constructor TestDialog (TestGUI)
location: class TestDialog
TestDialog testdialog = new TestDialog(TestGUI.this);
Could anyone see the problem?
Thank you
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TestGUI implements ActionListener{
static JPanel contentPane;
static JMenuBar menuBar;
static JMenuItem item;
static JButton link;
TestGUI(){
contentPane = new JPanel(new FlowLayout(FlowLayout.CENTER,30,30));
link = new JButton("Link");
link.addActionListener(this);
contentPane.add(link);
public void actionPerformed(ActionEvent e){
String actionCommand = e.getActionCommand();
if(actionCommand.compareTo("Link")==0){
TestDialog testdialog = new TestDialog(TestGUI.this);   
testdialog.setVisible(true);
public static void main(String args[]){
JFrame frame = new JFrame("Test GUI");
TestGUI object = new TestGUI();
frame.setJMenuBar(menuBar);
frame.setContentPane(contentPane);
frame.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e)
{System.exit(0);}});
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
class TestDialog extends JDialog implements ActionListener{
TestDialog(JFrame parent){
super(parent, "Test dialog", true);
JPanel panel = new JPanel();
panel.add(new Label("Working"));
getContentPane().add(panel);
pack();
public void actionPerformed(ActionEvent e){
String actionCommand = e.getActionCommand();
}

Answer 1

TestDialog has only the constructor: TestDialog(JFrame parent)
you call: new TestDialog(TestGUI.this);
but TestGUI doesn't inherit from JFrame!