Description
In the game of Bingo, the caller randomly selects a set of Bingo balls, one at a time, from
a Bingo cage and calls out the letter and number printed on the little ball. Each player
checks for that particular number on their Bingo card, a 5 × 5 grid. If the number is there,
then the player will cover the specific grid that contains the number. The player’s goal is
to be the first to cover the the grids in a previously-agreed-upon pattern, often a straight
vertical or horizontal line.
Immediately after the caller’s announcement of the current ball, a player who has the
necessary pattern will call out “Bingo!”. Before claiming the prize, the player proves the
validity by calling out the numbers of each of the covered squares that make up the pattern.
The caller verifies that each of the balls were actually called, by searching through the
called balls.
In this assignment, you will create a class BingoBall and create the data structure that
contains the called balls.
Quick Start
(1) Create a fresh directory to contain this assignment: CSC115/assn1 is a good name.
Download this pdf file and the file BingoBall.java into that directory.
(2) Create a subdirectory, called docs, for documentation and download the html files.
When you open the local version of this pdf, and click on the following links, the
specifications for the required Java classes will open. Try it:
• BingoBall specifications
• BingoCalls specifications
If you are not using a local version of this document and/or have not created a
subdirectory called docs to store the html files, you can open one of the html files
by double-clicking on it.
(3) Carefully examine both of the specification documents. Note the similarity to the
standard documentation pages for all Java classes. For example, search for java
and Random and note the layout of information.
(4) Compile BingoBall.java. It compiles and runs without errors, but it is not very
useful in its initial condition.
(5) Open BingoBall.java in a text editor. A basic template has been started, to guide
you through the process of creating a class by taking the following recommended
steps:
(a) Create the shell of the program (done for you): This is done by creating the
class definition and all the public methods as directed in the specification
document. The methods are empty, except when they must return a value,
in which case a dummy value is returned. Once the shell is created, the source
code can be compiled.
(b) Decide what the private data fields will be: Note that for BingoBall a public
static final array has been initiated for you. This is NOT a data field, but
a constant value that you may find helpful. (See the comments in the source
code).
(c) Implement the methods one at a time, starting with the easiest ones.
Note that the main method contains a set of statements that tests the code. You
may add more tests if you like.
(6) After completing and thoroughly testing BingoBall, create the BingoCalls class,
again following the specifications. Create your own main method in this class to
thoroughly test all the methods in BingoCalls.
Detailed Instructions
Complete both the BingoBall and BingoCalls classes adhering to the following guidelines:
• The associated html file contains a summary and detailed explanation of what each
method must do, along with details about any input or returned value. Note that the
information provided is generated from header comments; you are welcome to use
these as required header commenting within your code.
• The main1method is to be used as a tester. The BingoBall class main method is
written for you.
Use this as the standard for testing all of your assignments.
• Compile and test your work frequently. Experienced programmers all do this,
knowing that a single syntax error or logical error is easier to fix when you’ve
only made a few changes to the document.
Some basic information (for details, see the textbook)
By convention, Java uses very specific names for many of the basic methods, making it
easier for users to remember what methods are available. For instance, every class in Java
has both an equals and a toString method. A basic class definition in Java will generally
contain the following:
• private data fields: These specifically define the attributes that make a particular
object of this class unique.
• One or more constructors: The constructors are created to allow the user to initialize an object. In most cases, the constructor sets the values of the data fields, as
specified by the argument list.
1Note to C programmers: unlike C, which requires only one main method for all of the files involved in
the running of a program, Java allows for each file to contain a main method. The actual main method that
runs the program is determined by the java command which names the file.
• Accessor–modifier methods: These methods are also referred to as the setters and
getters. Where the user is permitted, each of the private data fields can be updated
or retrieved using these methods.
• A method to determine equivalence between objects of the class: It is always
useful to be able to determine what conditions are necessary for two objects of
the same class to be deemed equivalent. With some objects, like strings or number
objects, this is intuitive. When it is not, the class designer must make the determination. Generally, the combined equality of the data fields is a safe determination,
but that may not always be the case.
• A method to format an informative String that describes the object: This is an
extremely useful method, both during development as a debugging tool, and also
for users to visualize the details of the objects.
BingoBall
The BingoBall consists of
• An uppercase letter, one of {B, I, N, G, O}.
• A number between 1 and 75. There is a matching of each of the letters to the
numbers that can be associated with it.
B: {1–15}
I: {16–30}
N: {31–45}
G: {46–60}
O: {61–75}
Some sample testing has been provided for you in the main method of the BingoBall
class. Note that the System.out.println statements with the BingoBall argument will
produce the output that is defined in the toString method. If the toString method has
not been created, then the address location of the reference is printed instead, which is not
very helpful.
BingoCalls
The BingoCalls class is basically a means to store the BingoBalls that were called during
a particular game. There will only be one instance of this class, as opposed to the 1–75
BingoBalls that can be instantiated. The main data field of this class will be an array of
BingoBalls. You may use a single array or a 2D array, or an array of arrays for this data
field. You MAY NOT use any of the collections data structures that extend the List class
from the java.util package.
In the design, the public methods allow the caller (the user) to
• create an empty container at the start of a game,
• add balls as they are called in the game,
• determine how many balls have been played,
• find and remove a ball that was accidentally added (mistakes can happen).
• confirm that a particular ball was played during the game, and
• empty the container of all balls, making it ready for a new game.
Java array data types must have a fixed size that is determined when the array is initialized.
(Note that the array must be initialized separately from the individual items inside the
array.) To allow for re-usability, we add a provision that doubles the size of the array when
the number of items exceeds the capacity of the array. To test for this, create the initial
array to hold a maximum of 5 items. Before each insert, make sure that the array is not
already full; if it is, then call a private method, created by you, that enlarges the array
before inserting the item.
As with the BingoBall, thoroughly test everything within the main method of the class.
Submission
Submit the following completed files to the Assignment folder on conneX. You will be
shown how to do this in the first week of labs:
• BingoBall.java
• BingoCalls.java
Please make sure you have submitted the required file(s) and conneX has sent you a confirmation email. Do not send [.class] (the byte code) files. Also, make sure you submit
your assignment, not just save a draft. Draft copies are not available to the instructors, so
they are not collected with the other submissions. We can find your draft submission, but
only if we know that it’s there.
A note about academic integrity
It is OK to talk about your assignment with your classmates, and you are encouraged to
design solutions together, but each student must implement their own solution.
Grading
Marks are allocated for the following:
• Proper programming style is demonstrated, as per the coding conventions on CSC115
conneX Resources.
• All methods are implemented exactly to the specifications.
• The main data field of BingoCalls must be an array, and not an object of any of
the List classes in the Java API, java.utils package.
• The private method that resizes the array in BingoCalls must copy the contents
of the original array one by one into the new larger array.
• The main method of BingoCalls must demonstrate that each method in BingoCalls
was tested.
You will receive no marks for any Java files that do not compile.