This code has forced NetBeans IDE 200512072015, Java 1.6 rc-b62 throw an
unexpected exception.

package net.phpvietnam.java.swing;

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.border.Border;
/**
 *
 * @author Admin
 */

    // This class represents a "canvas" that can display colored shapes
public class ShapeCanvas extends JPanel implements ActionListener {
    

    
    public enum shape { Rectangle, Circle, Eclipse, Polygon }
    Color currentLineColor = Color.red;     // default color; when a shape is
created, this is its color
    Color currentFillColor = Color.blue;     // default color; when a shape is
created, this is its color
    
    /** Creates a new instance of ShapeCanvas */
    // Constructor: set background color of the drawing area to white
    /*
    ShapeCanvas() {
        setBackground(Color.red);
    }
     */
    public void paintComponent(Graphics g) {
        
        super.paintComponent(g);
        // Call the paintComponent method from
        // the superclass, JPanel.  This simply
        // fills the entire component with the
        // component's background color.
        
        int width = getSize().width;   // Get this component's width.
        int height = getSize().height; // Get this component's height.
    }
    
    public void actionPerformed(ActionEvent event) {
        // Called to respond to action events.  The 4 shape-adding
        // buttons have been set up to send action events to this canvas.
        // Respond by adding the appropriate shape to the canvas.
        // This method is divided into 2 parts
        // 1: Determine which shape should be drawn: get the order from button event
        // 2: Get the order from JComboBox. If they exist, get the color and
paint them with the shape.
        
        // Check the color first because if I check the button first, I will
want to draw the Shapes
        // before I have any info on the colors ordered.
        // I will use a eventSource object to store information on the source
that generates the events
        // Please be advised that I have set the ActionCommand first. He he.pcdinh
        
        Object eventSource = event.getSource();
        
        System.out.println("Source: "+eventSource);
        
        if (eventSource instanceof JButton) {
            System.out.println("Source: JButton");
            
        }
        
        String command = event.getActionCommand();
        System.out.println("Command: "+command);
        if (command.equals("Rectangle")) {
            System.out.println("Command: "+command);
        } else if (command.equals("Circle")) {
        }
        
        else if (command.equals("Eclipse")) {
        }
        
        else if (command.equals("PolygonShape")) {
        }
    }
    
    private void drawShapes(enum shape) {
// Originally, I use private void drawShapes(String shape) but
// after that I decided to try out enum feature. An exception has been thrown.
        
        switch (shape) {
            case "Rectangle":
                break;
            case "Eclipse":
                break;
            default:
                break;
        }
        
    }

    
}


Log file is attached below