Class Diagram for the Chess Game

We’ll create the class diagram for the chess game. In the class diagram, we will first design the classes and then identify the relationship between classes according to the requirements for the chess game problem.

Components of Chess#

As mentioned earlier, we'll follow the bottom-up approach to designing a class diagram for the chess game.

Box#

A Box is a specific position/block on the 8x8 chessboard which is defined by row x and column y, respectively.

Chessboard#

A Chessboard is the 8x8 board that stores all the current game's active pieces. It is identified by the date of its creation and can be updated or reset.

Piece#

A chess Piece can only be black or white in color. It might be alive or killed depending on the moves made by the opposition. There can be six types of pieces (Rook, Pawn, King, Queen, Knight, and Bishop derived from Piece) that have their respective moves based on the rules of the game which decides whether they are eligible to move or not.

Move#

A Move is the displacement of a Piece from one Box to another on the chessboard. It may or may not kill a piece of the opposing player.

Account, Player, and Admin#

The Account class is a parent class that has two types: Player and Admin. These classes are derived from the Account class. This class stores the user ID, password, and account status.

Player: This derived class represents the players of the game and all records of the games played. It also keeps track of whether or not the player's chosen color is white.

Admin: This derived class decides whether or not a user account is blocked.

Chess move controller#

The ChessMoveController class validates the moves made by a player and responds accordingly.

Chess game view#

The ChessGameView class represents the game view. The ChessGame class updates the ChessGameView class.

Chess game#

The ChessGame represents the gameplay of chess. It keeps track of the moves played by both the players, the turns, and the game status.

Enumerations and custom data types#

The enumerations and custom data types required in the chess game design problem are listed below:

• GameStatus: This enumeration keeps track of the active status of the player and the game, i.e., who wins and whether or not the game is a draw.

• AccountStatus: We need to create an enumeration to keep track of the account status, whether it is active, canceled, closed, blocked, or none.

• Person: This is used to store information related to a person like a name, street address, country, etc.

Relationship between the classes#

Now, we'll discuss the relationships between the classes we have defined above for our chess game design.

Association#

The class diagram has the following association relationships:

• The Move class has a one-way association with Player.

• The Player class has a one-way association with ChessMoveController.

• The ChessMoveController class has a one-way association with ChessGame.

• The ChessGame class has a one-way association with ChessGameView.

• The ChessGameView class has a one-way association with Player.

Aggregation#

The class diagram has the following aggregation relationships:

• The ChessGame class contains the Player.

Composition#

The class diagram has the following composition relationships.

• The Box class is composed of Piece.

• The ChessBoard class is composed of Box.

• The ChessGame class is composed of ChessBoard.

• The ChessGame class is composed of Move.

Inheritance#

The following classes demonstrate an inheritance relationship:

• Both, Admin and Player extend the Account class.

• The King, Queen, Knight, Bishop, Rook, and Pawn classes extend the Piece class.

Note: We have already discussed the inheritance relationship between classes in the component section above one by one.

Class diagram for the Chess game#

Here’s the complete class diagram for our chess game:

Design pattern#

The following design patterns have been used in the class diagram:

• Singleton design pattern: This pattern ensures the existence of a single instance of the chessboard at a given moment due to the shared nature of the chessboard as a resource. Multiple instances can cause the game state to become inconsistent.

• Command design pattern: This pattern is used to encapsulate the move logic for each chess piece. Each chess piece has its own implementation of the move command, which allows it to move according to the rules defined for it. For example, the knight moves in an L-shape pattern, or the rook can move only horizontally or vertically on any number of boxes.

The following design patterns can also be used to design chess:

• The Iterator design pattern would enable the game to move sequentially by allowing the pieces to behave in a uniform manner where the user does not need to know the specifications or underlying logic behind the moves of the pieces.

• The State design pattern ensures the encapsulation of the state logic of each piece, since all the chess pieces have their own respective implementations of checkmate states which makes them behave differently from each other depending on the situation.

• The Observer design pattern enables the chess pieces to act as observers where the chessboard is the subject. As soon as the state of the board changes, the pieces are notified to adapt to the changes accordingly. This decouples the pieces from the chessboard.

AI-powered trainer#

At this stage, everything should be clear. If you encounter any confusion or ambiguity, feel free to utilize the interactive AI-enabled widget below to seek clarification. This tool is designed to assist you in strengthening your understanding of the concepts.

We have completed the class diagram of the chess game according to the requirements. Now, let's design its activity diagram in the next lesson.