Java Tutorial: Building a Sudoku Application

Introduction

• Presenter: Ryan
• Objective: Build a complete application from scratch (Sudoku Game)
• Complement to the course: "Working Class Java"

Teaching Approach

• Preference for building things as a learning method
• Aims to answer common questions:
  • When to use interfaces or abstract classes?
  • Is there a perfect software architecture?

Problem Domain Analysis (BOM)

• Key Questions:
  • What data does the app need to represent?
  • What problems does the app need to solve for its users?
• Focus for this session: Classes within the problem domain.

Setting Up the Project

• IDE: IntelliJ IDEA
• Project Setup:
  • Correct package name.
  • Delete unnecessary sample files.
• Building foundational classes for the Sudoku game.

Key Classes Introduced

1. GameState Enum - Represents different states of the game.

2. Sudoku Grid - Represented as a 2D array (constant size of 9).

   • Immutable grid state; employs a copy method to prevent external changes.
   • Implements Serializable for easy data storage.

3. Coordinates Class

   • Contains X and Y values.
   • Implements equals and hashCode methods for HashMap usage.

Interfaces and Coding Strategies

• Use of interfaces for design by contract.
• Importance of immutability discussed.
• Discussion on using static final variables and enums for unchanging data.

Building the Sudoku Application

Entry Point Setup

• Main entry point class renamed to "SudokuApplication".
• Launch mechanism from IntelliJ to prevent crashes.

User Interface Design

• UI designed using Envision prior to implementation.
• Event listener interface nested within the IUserInterface contract for organization.
• Custom TextField class maintaining X and Y coordinates.
• Usage of Regular Expressions for user input validation.

Drawing UI Elements

• Creating grid lines using JavaFX Rectangle class.
• Efficient management of 81 text fields using a HashMap.

User Interaction Handling

• Methods for handling user inputs and keeping track of game state.
• Use of alert dialogs to communicate game completion.

Logic and Back-End Implementation

Game Logic Class

• Encapsulates rules to verify Sudoku game validity.
• Use of helper functions to maintain code legibility and avoid repetition.
• Handling nested loops cautiously to avoid performance issues.

Sudoku Utilities

• Utility class for operations like copying Sudoku arrays.
• Backtracking logic implemented to handle unsuccessful attempts during number allocation.
• Explanation of a two-stage backtracking algorithm.

Storage Mechanism

• Persistent storage implemented through file handling (e.g., game data file).
• Exception handling for I/O operations.

Conclusion

• Encouragement to explore more resources and tutorials.
• Acknowledgments to friends and supporters.

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Further Resources:

• Check Ryan's YouTube channel for live Q&A sessions.
• Available tutorials on platforms like Udemy and Skillshare.