COSC 2391/2401 | Assignment Part 1 Casino Style Gaming Wheel | Console

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Implementation Specifications

Your primary goal is to implement the provided GameEngine, Player, GameEngineCallback and Slot interfaces, in classes called GameEngineImpl, SimplePlayer, GameEngineCallbackImpl and SlotImpl. You must provide the behaviour specified by the javadoc comments in the various interfaces and the generated javadoc index.html. The imports in show you which packages these classes should be placed in. Additionally, you are required to implement the applyWinLoss() method overrides in the BetType enum in order to implement the win/loss behaviour described in Table 1.

More specifically, you must provide appropriate constructors (these can be determined from and are also documented in the relevant interfaces) and method implementations (from the four interfaces) in order to ensure that your solution can be complied and tested without modifying the provided SimpleTestClient.java1 (although you can and should extend this class to thoroughly test your code). A sample output trace (OutputTrace.txt) is provided to help you write correct behaviour in the GameEngineImpl which in turn calls the GameEngineCallbackImpl class to perform the actual logging. You should follow the exact output format since it is clearly specified and this facilitates automated testing.

Your client code ( and any extended derivatives) should be separate from, and use, your GameEngineImpl implementation via the GameEngine interface. Furthermore, your client should NOT call methods on any of the other interfaces/classes since these are designed to be called directly from the GameEngine2

The main implementation classes GameEngineImpl and GameEngineCallbackImpl are described in more detail below. The SimplePlayer and SlotImpl are relatively straightforward data classes and should not need further explanation for their implementation (beyond the comments provided in the respective interfaces).

GameEngineImpl class

This is where the main game functionality is contained. All methods from the client are called through this class (see footnote). Methods in the supporting classes should only be called from GameEngineImpl.

1. A common mistake is to change the imports (sometimes accidentally!) Therefore, you MUST NOT change the imports and must place the class implementations in the expected package so that we
can test your code with our own testing client.

2 This is because we will be testing your code with our own client by calling the specified GameEngine methods. We will not call methods on any other classes and therefore if your GameEngineImpl code expected other methods to be called from the client (rather than calling them itself) it won’t work!
The main feature of this class that is likely different to previous code you have written is that the GameEngineImpl does not provide any output of its own (i.e. it SHOULD HAVE NO println() or log() statements other than for debugging and these should be commented or removed prior to submission). Instead it calls appropriate methods on the GameEngineCallback as it runs (see below) which is where all output is logged to the console for assignment part 1.

This provides a good level of isolation and will allow you to use your GameEngineImpl unchanged in assignment 2 when we add a graphical AWT/Swing use interface!

NOTE: Your GameEngineImpl must maintain a collection of Players AND a collection of GameEngineCallbacks. When a callback method should be called this must be done in a loop iterating through all callbacks. Note that each callback receives the same data so there is no need to distinguish them (i.e. they are all the same and not player specific). gives an example for three players with each bet type and shows it is trivial to add more (simply increase the array size by adding to the initialiser).

GameEngineCallbackImpl class

The main purpose of this class is to support the user interface (view) which in assignment part 1 consists of simple console/logging output. Therefore, all this class needs to do is log data to the console from the parameters passed to its methods. Apart from implementing the logging (we recommend String.format() here) the main thing is to make sure you call the right method at the right time! (see below). You should also as much as possible make use the of the overidden toString() methods you will implement in SimplePlayer and SlotImpl since this will simplify the logging!

The only class that will call the GameEngineCallbackImpl methods is the GameEngineImpl class. For example as the spin(…) method is executing in a loop it will call the nextSlot(…) method on the GameEngineCallbackImpl (via the GameEngineCallback interface). Details of the exact flow and where GameEngineCallback methods should be called are provided in the GameEngineImpl source code and associated Javadoc.

IMPORTANT: The main thing to watch out for (i.e. “gotcha”) is that this class should not manage any game state or implement any game-based functionality which instead belongs in the GameEngineImpl. The core test here is that we should be able to replace your GameEngineCallbackImpl with our own (which obviously knows nothing about your implementation) and your GameEngineImpl code should still work. This is a true test of encapsulation and programming using interfaces (i.e. to a specification) and is one of the main objectives of this assignment!



Before you start coding make sure you have thoroughly read this overview document and carefully inspected the supplied Java code and Javadoc documentation. It might take a bit of work but the more carefully you read before beginning coding the better prepared you will be!

1. Start by importing the supplied Java project It will not compile yet but this is normal and to be expected.
2. The first step is to get the code to compile by writing a minimal implementation of the required classes. Most of the methods can be left blank at this stage, the idea is satisfy all of the dependencies in that are preventing successful compilation. Eclipse can help automate much of this with the right click Source ... context menu but it is a good idea to write at least a few of the classes by hand to make sure you are confident of the relationship between classes and the interfaces that they implement. It will also help familiarise you with the
 class/method names and their purpose. We have already provided a partial implementation of GameEngineCallbackImpl showing the use of the Java logging framework but you will need to complete it by implementing the missing methods.

3. When writing the SimplePlayer class you will need a 3 argument constructor for the code to compile. You could leave this blank at this stage but might as well implement it by saving the parameters as instance variables/fields. In fact, you might as well implement the methods while you are there since they are straightforward. HINT: In my (Caspar’s) solution most of the methods of SimplePlayer are one liners, except for setBet() which is a few more lines since it requires some basic validation.
4. Once the code can compile you are ready to start implementing the GameEngineImpl. You can start with the simple methods like addPlayer(), addGameEngineCallback() etc.
5. The next functionality to work on is creating the gaming wheel as a Collection of Slot which is returned to the client which logs it so you can CAREFULLY check correctness against the


6. The spin() method involves the most code but even this is fairly small if well structured. In fact, this assignment doesn’t require a lot of lines of code, it is about understanding concepts and putting the pieces together to make it work!
7. When implementing spin(…) the main focus is calling nextSlot(…) and result(…) on the

GameEngineCallBackImpl (via the GameEngineCallback interface). You can ignore the delay for now and use temporary log/println statements and the debugger to help you compare against the OutputTrace.txt.

8. Once you get this far you have the basic structure underway so you can finish by implementing the applyWinLoss() methods in BetType and calling them from calculateResult() in the

GameEngine. Again, use the log output of the client and OutputTrace.txt to check for correctness.

9. Finally add in the logging calls into the GameEngineImpl and implement the delay in the spin method and you are pretty much done!
10. Copy SimpleTestClient (you can call it MyTestClient for example) and update it with some more through testing code, debug as necessary to fix any issues and you are done :)


1. You should aim to provide high cohesion and low coupling.
2. You should aim for maximum encapsulation and information hiding.
3. You should rigorously avoid code duplication.
4. You should comment important sections of your code remembering that clear and readily comprehensible code is preferable to a comment.
5. Since this course is concerned with OO design you should avoid the use of Java 8+ lambdas which are a functional programming construct.
6. You should CAREFULLY read the instructions and supporting code and documents. This assignment is intended to model the process you would follow writing real industrial code.
8. Marking emphasis will be on the quality of your code as well as your ability to implement the specified functionality.

Submission Instructions

• You are free to refer to textbooks and notes, and discuss the design issues (and associated general solutions) with your fellow students or on Canvas; however, the assignment should be your OWN INDIVIDUAL WORK and is NOT a group assignment.
• You may also use other references, but since you will only be assessed on your own work you should NOT use any third-party packages or code (i.e. not written by you) in your work.

The source code for this assignment (i.e. complete compiled Eclipse project3) should be submitted as a .zip file by the due date. You can either zip up the project folder or use the Eclipse option export->general->archive. You will be provided with further submission instructions on Canvas before the deadline.


Late submissions are handled as per usual RMIT regulations - 10% deduction (2.5 marks) per day. You are only allowed to have 5 late days maximum.


Layout of the gaming wheel as per the logs of OutputTrace.txt

NOTE: You do not need to implement any graphics or UI for assignment 1, this will done according to a precise specification in assignment 2.

3. You can develop your system using any IDE but will have to create an Eclipse project using your source code files for submission purposes.


This wheel image is based on

The original was licensed under Creative Commons CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

The provided file Basic_roulette_wheel_1024x1024.png is a modification by Caspar to replace the duplicated 35 with a 25 in the correct position and is the file that should used for this assignment!

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