help needed

[babywen]

my program doesn't display the shapes after the button is clicked ..
can someone help me with this ..

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

public class DrawShapes extends JFrame {

    public DrawShapes() {
        JPanel panel = new JPanel();
        final JButton circle = new JButton("Circle");
        JButton square = new JButton("Square");
        JButton rectangle = new JButton("Rectangle");
        JButton lines = new JButton("Lines");

        panel.setLayout(new FlowLayout());
        panel.add(circle);
        panel.add(square);
        panel.add(rectangle);
        panel.add(lines);

        add(panel, BorderLayout.SOUTH);
        //add((new Drawings(Drawings.CIRCLE)), BorderLayout.CENTER);

        circle.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e){
                if(e.getSource().equals(circle))
                add((new Drawings(Drawings.CIRCLE)), BorderLayout.CENTER);
            }
        });

        square.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e){
                add((new Drawings(Drawings.SQUARE)), BorderLayout.CENTER);
            }
        });

        rectangle.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e){
                add((new Drawings(Drawings.RECTANGLE)), BorderLayout.CENTER);
            }
        });

        lines.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e){
                add((new Drawings(Drawings.LINE)), BorderLayout.CENTER);
            }
        });

    public static void main (String [] args) {
        DrawShapes frame = new DrawShapes();
        frame.setTitle("Paint Application");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,500);
        frame.setVisible(true);

    }

}


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

public class Drawings extends JPanel {

    public static final int CIRCLE = 1;
    public static final int SQUARE = 2;
    public static final int RECTANGLE = 3;
    public static final int LINE = 4;

    private int type = 1;


    public Drawings(int type) {
        this.type = type;
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        int width = getSize().width;
        int height = getSize().height;

        switch(type) {

            case CIRCLE:
                g.setColor(Color.BLACK);
                g.fillOval((int)(0.1*width), (int)(0.1*height), (int)(0.8*width), (int)(0.8*height));
                break;

            case SQUARE:
                g.setColor(Color.BLUE);
                g.fillRect((int)(0.1*width), (int)(0.1*height), (int)(0.8*width), (int)(0.8*height));
                break;

            case RECTANGLE:
                g.setColor(Color.RED);
                g.fillRect((int)(0.1*width), (int)(0.3*height), (int)(0.8*width), (int)(0.3*height));
                break;

            case LINE:
                g.setColor(Color.BLACK);
                g.drawLine(100,150,width-100, height-250);
                g.drawLine(width-100,150,100,height-250);
                break;

        }
    }

    public void setType(int type) {
        this.type = type;
        repaint();
    }

    public int getType() {
        return type;
    }
}

thanks ..