For your third lab, you will create a Java program that draws some shapes.

First, create the following classes:

• Shape class, that contains the method void draw(Graphic g)
• Rectangle class, subclass of shape
• Constructor takes 5 input parametrs: ints x, y, width, height, and Color c
  
• public void draw(Graphic g) method that overrides the shape draw method
• Circle class, subclass of shape
• Constructor takes 4 input parameters:  ints  x, y, radius ((x,y) is the center point of the circle), and Color C
  
• public void draw(Graphic g) method that overrides the shape draw method
• Triangle class, subclass of shape
• Constructor takes 7 input parameters:  ints  x1, y1, x2, y2, x3, y3 (vertices), and color C
  
• public void draw(Graphic g) method that overrides the shape draw method

Next, create a new class ShapePanel, subclass of JPanel that contains the following methods

• Constructor, sets a nice preferred size
• public void addShape(Shape s), adds the shape s to the panel (that is, adds s to an array of shapes stored as an instance variable).  There can be a hard limit to the number of shapes that can be added to the ShapePanel, but don't use magic numbers -- use constants instead.  This function should probably cause the panel to be repainted (that is, call the repaint method)
  
• protected void paintComponent(Graphics g).  Overrides the standard paintComponent method.  First, call the superclass method (to paint background & such), and then draw all of the shapes that have been added to this panel.

Finally, create a new class MainPanel, sublcass of JPanel that:

• Contains two panels:  A ShapePanel on top, and a standard JPanel on bottom
• The JPanel on bottom should contain 3 buttons: add circle, add rectangle, add triangle
• Pressing one of these buttons should create the approprate random shape with a random color
• You can use 3 different button handlers (that is, ActionListeners) for this, if you want to (my solution uses 3 handlers)

Grading

You will be graded on several criteria:

Program decomposition:  25

Did you break your code into the required classes & subclases, did you use polymorphism to draw the shapes correctly?

Coding standards 10

Be sure to do proper indentation & commenting.  Also, no magic numbers!  Use constants instead.

See the Coding Standards for more information

Working

Program compiles and puts up a window:  20
Contains all required buttons: 20
Buttons correctly put up random shapes 25

Submission

All file(s) required for your project should be in the folder https://www.cs.usfca.edu/svn/<username>/cs112/Lab3/