YCP Logo Assignment 3: Disk Placement Game, Part II

Due: Friday, Oct 1st by 11:59 PM

CS 201 - Assignment 3

Your Task

Your task is to complete your implementation of the Disk Placement game described in the previous assignment. You should implement all of the features described.

You will use the Disk class you implemented in the previous assignment as an important building block in the completed game.

Getting Started

Start by making a copy of your CS201_Assign2 project (which you completed in the previous assignment.)

To make a copy of a project in Eclipse:

  • Right-click on the name of the project in the Package Explorer
  • Choose Copy
  • From the Edit menu, choose the Paste menu item

When you choose Paste, you will see a dialog box similar to the following one:


Change the project name to CS201_Assign3:


Click OK.

Specifications and Hints

You will make all of your code changes to the DisksPanel class, which implements the game play.

You should add whatever fields are necessary to represent the state of the game. You will probably want to use an array of Disk elements to represent the disks that have been placed.

Mouse events

The handleMouseMove method is called whenever the mouse pointer is moved within the window. You can get the x and y coordinates as follows:

int x = e.getX();
int y = e.getY();

where e is the parameter to the method, an instance of the MouseEvent class. You will need state variables to keep track of the current location of the mouse pointer.

The handleMouseClick method is called whenever a mouse button is clicked. You should use this method to place a disk in the window. You will need to check to ensure that the placed disk

  1. does not overlap any previously placed disk, and
  2. is placed entirely within the bounds of the panel

The WIDTH and HEIGHT constants provide the width and height of the panel.

Remember that you will need to call repaint to force the contents of the panel to be redrawn when the game state changes.

Disk creation

When the next disk is ready to be placed, its radius should be randomly chosen in the range 10..44, inclusive. You can generate random numbers using an instance of the java.util.Random class as a field:

private Random rand;

Create an instance in your constructor:

rand = new Random();

You can generate a random number uniformly chosen from the range 0..n-1, inclusive, using the method call


The paint method

The paint method should use the fields representing the game state to render the current configuration.

Some java.awt.Graphics methods that will be useful:

  • setColor - Sets the drawing color.
  • drawOval - Draws an outlined oval. If the width and height are the same, draws an outlined circle.
  • fillOval - Draws a filled oval. If the width and height are the same, draws a filled circle.
  • setFont - Sets the current font used for drawing text.
  • drawString - Draws a string of text characters.

Running the program

To run the program, right-click on DisksApp.java and choose Run as->Java Application.


The grading will be done as follows:

  • Displaying the outline of the next disk to be placed - 15%
  • Allowing disks to be placed, drawing them - 30%
  • Detecting overlap and out-of-bounds - 20%
  • Keeping score, displaying score - 15%
  • Detecting end of game, displaying "Game over" - 20%
  • Growing the disks array as needed, rather than preallocating a large array - 5%


Export your finished program to a zip file (right-click on the project, then Export...->Archive File). Upload the zip file to the marmoset server as project assign3. The server URL is


IMPORTANT: after uploading, you should download a copy of your submission and double-check it to make sure that it contains the correct files. You are responsible for making sure your submission is correct. You may receive a grade of 0 for an incorrectly submitted assignment.