Draw a filled in circle when the mouse is clicked

[muniba]

plz tell me where i am stuck.how could i solve this

package drawing;


import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.File;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.*;
import javax.swing.event.*;

/**
 *
 * @author
 */
public class RunProgram extends JPanel implements ActionListener, ChangeListener, MouseListener {
    private JPanel phasePanel;
    static JPanel contentPane;
    private static JMenuBar bar;
    private JPanel picture1;
    private JPanel picture2;
    private Component toolBar;

    /** Creates <strong class="highlight">a</strong> new instance of RunProgram */
    public RunProgram() {
        setLayout(new BorderLayout());

        //Create <strong class="highlight">a</strong> panel and make it the content pane.
        contentPane = new JPanel(new BorderLayout());
        contentPane.setBorder(BorderFactory.createRaisedBevelBorder());

        //create panel <strong class="highlight">to</strong> show original pictures
        picture1 = new JPanel();
        picture1.addMouseListener((MouseListener) this);
        // picture1.setBackground(Color.BLUE);
        picture1.setBorder(BorderFactory.createLoweredBevelBorder());
        picture1.setPreferredSize(new Dimension(450, 1000));

        picture2 = new JPanel();
        picture2.addMouseListener(this);
        //picture2.setBackground(Color.GREEN);
        picture2.setBorder(BorderFactory.createLoweredBevelBorder());
        picture2.setPreferredSize(new Dimension(450, 1000));

        JPanel controlPanel = new JPanel();
        //controlPanel.setBackground(Color.GRAY);
        controlPanel.setBorder(BorderFactory.createLoweredBevelBorder());
        controlPanel.setPreferredSize(new Dimension(800, 50));
        controlPanel.setLayout(new FlowLayout());

        contentPane.add(phasePanel, BorderLayout.SOUTH);
        contentPane.add(toolBar, BorderLayout.NORTH);
        contentPane.add(picture1, BorderLayout.WEST);
        contentPane.add(picture2, BorderLayout.EAST);
        contentPane.add(bar, BorderLayout.NORTH);
        contentPane.add(toolBar, BorderLayout.CENTER);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        JFrame frame = new JFrame("ImageViewer");
        frame.add(new RunProgram());
        frame.setSize(1100, 900);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setJMenuBar(bar);
        frame.setContentPane(contentPane);
        frame.setVisible(true);
    }

    public void mouseClicked(MouseEvent e) {
        x = e.getX();
        y = e.getY();
        System.out.println("x = " + x + "y = " + y);
        drawCircle(e.getX()-(radius/2), e.getY()-(radius/2));
        repaint();
    }

    public void drawCircle(int x, int y) {
        Graphics g = getGraphics();
        g.drawOval(x - radius, y - radius, 2 * radius, 2 * radius);
        g.setColor(Color.BLACK);
        g.fillOval(x - radius, y - radius, 2 * radius, 2 * radius);
    }

    public void mousePressed(MouseEvent e) {}
    public void mouseReleased(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}

    int x,  y;
    int radius = 20;

    @Override
    public void stateChanged(ChangeEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub

    }
}

[nickguletskii]

contentPane.add(phasePanel, BorderLayout.SOUTH);
		contentPane.add(toolBar, BorderLayout.NORTH);
		contentPane.add(picture1, BorderLayout.WEST);
		contentPane.add(picture2, BorderLayout.EAST);
		contentPane.add(bar, BorderLayout.NORTH);
		contentPane.add(toolBar, BorderLayout.CENTER);

phasePanel
toolBar
bar

Are not initialised:

private JPanel phasePanel;
	static JPanel contentPane;
	private static JMenuBar bar;
	private JPanel picture1;
	private JPanel picture2;
	private Component toolBar;