Probleme fermeture fenetre en java

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

public class BaseGraph {
    public static void main(String args[]) {
	JFrame frame = new JFrame();
	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	frame.setTitle("ma fenetre");
	frame.setSize(400,400);
	Container contentPane = frame.getContentPane();
	Container c = frame.getContentPane();
	JButton bouton1 = new JButton("Clique");
	JButton bouton2 = new JButton("Fermer");
	bouton1.addActionListener(new MonAction());
	Graph g = new Graph();
	GraphPanel gp = new GraphPanel(g);
	JScrollPane  panel = new JScrollPane ();
	JPanel panel2 = new JPanel();
	panel2.add(bouton1);
	panel2.add(bouton2, BorderLayout.SOUTH);
	contentPane.add(panel2);
	panel.getViewport().add(gp); 
	frame.setVisible(true);
    }
}

class MonAction implements ActionListener {
    public void actionPerformed(ActionEvent event){
	this.dispose();
    }
}

florent@florent-laptop:~/Documents/Info/A2/S2/TP$ javac BaseGraph.java 
BaseGraph.java:31: cannot find symbol
symbol  : method dispose()
location: class MonAction
        this.dispose();
            ^
1 error