Assignment 6: Class Design, Comparable Interface, Layout Managers

Assignment 6: Class Design, Comparable Interface, Layout
Managers

For this assignment, you’ll be making a program that simulates the popular game Rock Paper
Scissors. For your reference: http://en.wikipedia.org/wiki/Rock_paper_scissors. The program
will allow the player to choose a throw, and then the computer will randomly choose its throw,
and the results are displayed to the player. There are three possible throws: rock, paper, and
scissors. Rock beats scissors, scissors beats paper, and paper beats rock. If both players throw the
same, then it is a tie. Please be sure to read all of the instructions before beginning.
The player chose rock by clicking on the Rock button, the computer randomly chose scissors,
and thus the player wins:

6.1: RPSThrow Class
This class will represent a player’s throw for a round of the game: rock, paper or scissors. Specs:
1. The class should implement the Comparable interface (see step 6).
2. It should have an enum for the 3 possible throws.
3. Private instance data to store the throw it represents (using the enum from step 2).
4. A static Random variable for the class to generate random numbers (see steps 8 and 10).
5. A constructor that takes in and stores the throw it represents (using the enum from step 2).
6. A compareTo method that will return (as an int) if this throw is “greater than” (ie, beats),
is “equal to” (ie, ties), or is “less than” (ie, loses to) another throw. Rock beats scissors,
scissors beats paper, and paper beats rock. Hint: from the java API: “compareTo returns a
negative integer, zero, or a positive integer as this object is less than, equal to, or greater
than the specified object.”
7. A toString method that will return the string representation of this throw, ie, “Rock”,
“Paper”, or “Scissors”. Hint: use the features of enums.
8. A static method called getRandomThrow that will return an RPSThrow that is randomly
chosen to be rock, paper, or scissors (this will be for the computer player).
9. In your javadocing for getRandomThrow, comment on why the getRandomThrow method
can and should be static. Be sure to include in your explanation the differences between a
static method and an instance method.
10. Javadoc the Random variable, and comment on why this variable can and should be static
in its javadocing. Be sure to include in your explanation the differences between a static
variable, an instance variable, and a local variable.

6.2: RPSResultPanel Class
The RPSResultPanel will be the middle panel in the window, as boxed in red:
Specs:
1. The class should extend JPanel.
2. The label should be stored in a private instance variable.
3. To center the label that displays the result:
a. Use a BoxLayout that lays components out on the Y axis (or the page axis)
b. Set the label’s X alignment (setAlignmentX) to be on the center
(Component.CENTER_ALIGNMENT) to set its horizontal position.
c. Add vertical glue above and below the label to force the label to be centered
vertically (represented by the blue lines in the above picture). See the Box class:
http://java.sun.com/javase/6/docs/api/javax/swing/Box.html
4. A method called setResult that takes in a String to set the label’s text.
5. In your javadocing for setResult, explain how providing this method, rather than
providing a getter for the label or leaving the variable public, respects abstraction and
encapsulation.

6.3: RPSComputerPanel Class
The RPSComputerPanel will be the panel that displays what the computer chose:
Specs:
1. The class should extend JPanel.
2. The labels should be stored in private instance variables.
3. Center the labels as you did for RPSResultPanel.
4. Provide a method called setComputerThrow that takes an RPSThrow parameter, that will
update the label to display what the computer chose.
6.4: RPSTitlePanel Class
This simple subclass of JPanel will display the title of the game. Use a Box Layout that lays
components out on the X axis (or the line axis). Add horizontal glue before and after the label to
center it horizontally:
6.5: RPSPlayerPanel Class
This will be the most complicated panel, because it will have buttons to allow the player to
choose his or her throw:
1. Use a Box Layout using the Y (or page) axis to lay the components out.
2. It should have a constructor that takes in an RPSComputerPanel and an
RPSResultPanel. These will be needed for step 3.
3. When the player clicks one of the buttons, the program should:
a. Create an RPSThrow object, depending on which button was pressed.
b. Get a random throw for the computer.
c. Determine who won the round, using the RPSThrow object’s compareTo method.
d. Update the player throw label, result label, and computer throw label
appropriately.
6.6: RPSMain
This class will have the main method that brings all the panels together:
1. Create a JFrame and set its default close operation to exit on close.
2. Create instances of RPSResultPanel, RPSComputerPanel, and RPSPlayerPanel.
3. Recall that the default layout manager for JFrames is Border Layout:
a. Add the result panel to the CENTER area
b. Add the player panel to the LINE_START area.
c. Add the computer panel to the LINE_END area.
d. Add the title panel to the PAGE_START area.
4. Set the preferred size of the frame to something reasonable (the examples above are
400x240)
5. Pack and make the frame visible.

Turn-in Procedure
Turn in the following files on T-Square. Double-check that you have submitted and not just
saved as draft (if the submission is successful, you will receive an e-mail from T-Square within a
few minutes). Also, be sure all of your files compile and run.
• RPSMain.java
• RPSThrow.java
• RPSPlayerPanel.java
• RPSComputerPanel.java
• RPSResultPanel.java
• RPSTitlePanel.java
• Any other files needed to run your submission
All .java files should have a brief descriptive javadoc comment.
Don't forget your collaboration statement. You should include a statement with every homework
you submit, even if you worked alone.