Null Pointer Exception

I am starting a drawing application where the user will be able to draw simple shapes with a mouse. The program complies with the "JGRASP" complier but when I run the program it crashes and displays

" Exception in thread "main" java.lang.NullPointerException
at DesktopFrame.<init>(DesktopFrame.java:165)
at mainDrawingApp.main(mainDrawingApp.java:27) "
below are all of my classes

{code}
/*
file: DesktopFrame.java
author: Andre Long
date: Febuary 3, 2009
purpose: To control all frames
*/
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JDesktopPane;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
import java.awt.Container;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.ImageIcon;
import javax.swing.Icon;
import java.awt.Dimension;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;
import java.awt.Color;

public class DesktopFrame extends JFrame
{
private JDesktopPane theDesktop; //the main frame
private Container container;
private JInternalFrame toolbox;
private andreFrame blankCanvas;
private JButton circleButton; //various JButtons
private JButton sphereButton;
private JButton squareButton;
private JButton rectangleButton;
private JButton triangleButton;
private JButton cylinderButton;
private JButton straightLineButton;
private JButton ploygonButton;
private enum shapeChoice{CIRCLE,SHPERE,SQUARE,RECTANGLE,TRIANGL E,CYLINDER,STRAIGHTLINE,PLOYGON};//enumeration

DesktopFrame()
{
super("Main Container for all Frames");
theDesktop = new JDesktopPane();
add(theDesktop);

JMenuBar bar = new JMenuBar(); //create a menu bar
JMenu menuHeaderShapes = new JMenu("Shapes"); //create a menu Header
JMenu menuHeaderCanvas = new JMenu("Drawing Canvas"); //create a menu Header
JMenu menuHeaderActions = new JMenu("Actions"); //create a menu Header

JMenuItem firstMenuItemShapes = new JMenuItem("Show Shapes");//create submenu item
menuHeaderShapes.add(firstMenuItemShapes); //add submenu item

JMenuItem secondMenuItemShapes = new JMenuItem("Hide Shapes");//create submenu item
menuHeaderShapes.add(secondMenuItemShapes); //add submenu item

JMenuItem firstMenuItemCanvas = new JMenuItem("New Canvas");//create submenu item
menuHeaderCanvas.add(firstMenuItemCanvas); //add submenu item

JMenuItem secondMenuItemCanvas = new JMenuItem("Colors");//create submenu item
menuHeaderCanvas.add(secondMenuItemCanvas); //add submenu item

JMenuItem thirdMenuItemCanvas = new JMenuItem("texture");//create submenu item
menuHeaderCanvas.add(thirdMenuItemCanvas); //add submenu item


JMenuItem firstMenuItemActions = new JMenuItem("Clear Canvas");//create submenu item
menuHeaderActions.add(firstMenuItemActions); //add submenu item

JMenuItem secondMenuItemActions = new JMenuItem("Undo");//create submenu item
menuHeaderActions.add(secondMenuItemActions); //add submenu item

bar.add(menuHeaderShapes); //add a menu to the menu bar
bar.add(menuHeaderCanvas); //add a menu to the menu bar
bar.add(menuHeaderActions); //add a menu to the menu bar


setJMenuBar(bar); //set menu bar for this application


firstMenuItemShapes.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{ /* constructor for JInternalFrame takes a title, and boolean values for
resize, close, maximize, minimize
*/
toolbox = new JInternalFrame("toolbox",true,true,true,true);
/* toolbox.setBounds(200,200,150,350); sets the "x","y",width and height we do not need because of
setSize() and setLocation below
*/
container = toolbox.getContentPane();
Icon circle = new ImageIcon(getClass().getResource("images/circle.jpg"));
Icon sphere = new ImageIcon(getClass().getResource("images/sphere.jpg"));
Icon square = new ImageIcon(getClass().getResource("images/square.jpg"));
Icon rectangle = new ImageIcon(getClass().getResource("images/rectangle2.jpg"));
Icon triangle = new ImageIcon(getClass().getResource("images/triangle.jpg"));
Icon cylinder = new ImageIcon(getClass().getResource("images/cylinder1.jpg"));
Icon straightLine = new ImageIcon(getClass().getResource("images/straightLine.jpg"));
Icon ploygonal = new ImageIcon(getClass().getResource("images/ploygonal.jpg"));
container.setLayout(new GridLayout(4,2));
container.add(circleButton = new JButton(circle));
container.add(sphereButton = new JButton(sphere));
container.add(squareButton = new JButton(square));
container.add(rectangleButton = new JButton(rectangle));
container.add(triangleButton = new JButton(triangle));
container.add(cylinderButton = new JButton(cylinder));
container.add(straightLineButton = new JButton(straightLine));
container.add(ploygonButton = new JButton(ploygonal));
theDesktop.add(toolbox);
toolbox.setVisible(true);
toolbox.setSize(150,200);
toolbox.setLocation(0,0);

}//end of actionPerformed
}//end of ActionListener
);//end Action Listener for firstMenuItemShapes


secondMenuItemShapes.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
toolbox.setVisible(false);
}//end of actionPerformed

}//end of ActionListener


);//end Action Listener for secondMenuItemShapes


firstMenuItemCanvas.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{ /* constructor for JInternalFrame takes a title, and boolean values for
resize, close, maximize, minimize
*/

blankCanvas = new andreFrame("Drawing Canvas",true,true,true,true);

/* toolbox.setBounds(200,200,150,350); sets the "x","y",width and height we do not need because of
setSize() and setLocation below
*/
container = blankCanvas.getContentPane();
theDesktop.add(blankCanvas);
blankCanvas.setVisible(true);
blankCanvas.setSize(300,300);
blankCanvas.setLocation(200,10);


}//end of actionPerformed
}//end of ActionListener
);//end Action Listener for firstMenuItemCanvas

circleButtonHandler fred = new circleButtonHandler();
circleButton.addActionListener(fred); /* connects the J buttons to an action to take */

MouseHandler mouseHandler = new MouseHandler();
blankCanvas.addMouseListener(mouseHandler);
blankCanvas.addMouseMotionListener(mouseHandler);

//blankCanvas.setTextStausBar();

}//end DesktopFrame constructor

private class circleButtonHandler implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
shapeChoice shapeChoiceStatus;
shapeChoiceStatus = shapeChoice.CIRCLE; //stores the fact the user clicked the circle button

}

}//end of ActionListener for circleButton

public class MouseHandler implements MouseListener,MouseMotionListener
{
public void mouseClicked(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Clicked at [%d,%d]",event.getX(),event.getY() ) );
}//end of mouseClicked function

public void mousePressed(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Pressed at [%d,%d]",event.getX(),event.getY() ) );
}//end of mousePressed function

public void mouseReleased(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Released at [%d,%d]",event.getX(),event.getY() ) );
}//end of mouseRelease function

public void mouseEntered(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Mouse entered at [%d,%d]",event.getX(),event.getY() ) );
blankCanvas.setBackground(Color.GREEN);
}//end of mouseEntered function

public void mouseExited(MouseEvent event)
{
blankCanvas.setTextStatusBar("Mouse outside blankCanvas ");
blankCanvas.setBackground(Color.WHITE);
}//end of mouseExited function

public void mouseDragged(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Mouse Draged at [%d,%d]",event.getX(),event.getY() ) );
}//end of mouseDragged function

public void mouseMoved(MouseEvent event)
{
blankCanvas.setTextStatusBar( String.format("Moved at [%d,%d]",event.getX(),event.getY() ) );
}//end of mouseMoved function


}//end of mouse interface


}//end class DesktopFrame

/*
file: andreFrame.java
author: Andre Long
date: Febuary 3, 2009
purpose: To constuct the drawing canvas to draw shapes
*/
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
import java.awt.Container;
import java.util.Vector;
import java.awt.Color;
import javax.swing.JLabel;

public class andreFrame extends JInternalFrame
{
private Vector<shape> vectorShapes; //must declare vector with a generic datatype of shape
private int shapeCount; //holds the number of shapes in the vector called vectorShapes
private int shapeType; //holds a number which determines the type of shape to draw
private shape currentShape; //represents the current shape the user is drawing
private Color currentColor; //represents the current drawing color
private boolean filledShape; //determines weather to draw a filled shape
private JLabel statusBar; //the status bar will display the coordinates of the current mouse position

andreFrame(String title, boolean resizable, boolean closeable, boolean maximizable, boolean iconifiable)
{
super(title,resizable,closeable,maximizable,iconif iable);
vectorShapes = new Vector<shape>();
add(statusBar);


}//end of constructor andreFRame

public void addShapeVector(shape someShape)
{
vectorShapes.add(someShape);
}//end of mehtod addShapeVector

protected void paintComponent(Graphics g)//overides the method paintComponent from JComponent
{

}//end of paintComponent

public void setShapeType(int numShapeType)
{

}//end of setShapeType

public void setCurrentColor(Color x)
{

}//end of setCurrentColor

public void setFilledShape(boolean trueFalse)
{

}//end of setFilledShape

public void clearLastShape()//removes the last shape drawn
{
shapeCount--;
if(shapeCount < 0)
{
shapeCount = 0;
}
}//end of clearLastShape

public void clearDrawing()//removes all shapes in the current drawing
{
shapeCount = 0;
}//end of clearDrawing

public void setTextStatusBar(String someString)
{
statusBar.setText(someString);
}

}//end of class andreFrame

/*
File: mainDrawingApp.java
Author: Andre Long
Date: January 27, 2009
Purpose: To serve as the main program which calls other classes for this drawing application
*/

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JDesktopPane;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;


public class mainDrawingApp
{

public static void main(String args[])
{
DesktopFrame theDesktop = new DesktopFrame();
theDesktop.setDefaultCloseOperation(JFrame.EXIT_ON _CLOSE);
theDesktop.setSize(800,480);
theDesktop.setVisible(true);

}// end main()

} //end class mainDrawingApp
{code}

I left out the shapes class because I am not using it yet
Can anyone tell me why I am getting a null pointer exception?
I believe I highlighted the problem lines with underlines

I would recommend that you edit your post so that you use code tags. This will allow your code will be well-formatted and readable. To do this, either highlight your code block and press the "code" button at the top above the message block or place the tag &#91;code&#93; at the top of your block of code and the tag &#91;/code&#93; at the bottom, like so:

Code:

---

{code}
  // your code block goes here
  // notice that the top and bottom tags are identical here
{code}

---

Also, indicate with "loud" comments just where the errors are occurring -- which line.

I inserted code tags and underlined the suspected problem lines

oops, my bad. I posted the tags for the Sun forum. For here use these:

Code:

---

[code]
  // your code block goes here
  // notice that the top and bottom tags are different here
[/code]

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Very sorry!

circleButton initialized in actionPerformed of firstMenuItemShapes.

before that action perform, circleButton is null
null object cant call its method