🎮 Console Tic-Tac-Toe Game ❌⭕

A progressive Java console application where a Human battles the Computer on a classic 3×3 grid.

Built by Harry Jay William C as part of an intensive software engineering bootcamp.

---

📖 About the Project

The Console Tic-Tac-Toe Game is a foundational Java application designed to strengthen logical thinking, control flow, and modular programming through the lens of a game everyone knows.

What starts as simply displaying an empty board on the console evolves across 5 developmental stages (Use Cases) into a fully functional, interactive Human vs Computer Tic-Tac-Toe engine — built using conditional logic, mathematical mapping, defensive programming, and clean method design.

Each Use Case isolates one specific responsibility, teaching Separation of Concerns and incremental software development in practice.

---

🌟 The Output

When executed, the program renders a clean, readable 3×3 game board on the console:

-------------
| - | - | - |
-------------
| - | - | - |
-------------
| - | - | - |
-------------

You won the toss! You go first.
Your symbol    : X
Computer symbol: O

Enter your slot (1-9): 5
Row: 1
Column: 1
true

---

🛤️ Evolution of the Codebase (UC1 – UC5)

This project was built incrementally, tackling one specific game mechanic at each stage.

Phase	Branch	Feature Focus	Technical Implementation
🟢 UC1	uc1-display-board	Board Rendering	Created a char[][] 2D array, initialised all cells with '-', and printed the grid using nested loops with horizontal/vertical separators.
🎲 UC2	uc2-toss-assign-symbols	Random Toss	Used java.util.Random to simulate a coin flip, applied conditional logic to assign X / O symbols, and stored game state in static variables.
⌨️ UC3	uc3-accept-user-input	User Input Handling	Captured the player's chosen slot (1–9) from the console using java.util.Scanner, isolated into its own method following Separation of Concerns.
🔢 UC4	uc4-slot-to-board-index	Mathematical Mapping	Converted the 1–9 slot number into zero-based (row, col) indices using integer division (slot-1)/3 and modulo (slot-1)%3.
🛡️ UC5	uc5-validate-move	Defensive Validation	Implemented boundary checking (row/col within 0–2) and occupancy checking (board[row][col] == '-') to accept or reject a move safely.

---

🧠 Key Concepts Mastered

Use Case	Concepts
UC1	2D Arrays, Initialization Logic, Nested Loops, Console Formatting
UC2	Random Number Generation, Conditional Logic, Game State Variables
UC3	User Input Handling, Method Creation, Separation of Concerns
UC4	Zero-based Indexing, Integer Division, Modulo Arithmetic, Utility Methods
UC5	Conditional Logic, Boundary Checking, Defensive Programming

---

🛠️ Technologies & Concepts Mastered

• Language: Java ☕
• Core Java APIs: java.util.Scanner, java.util.Random
• Data Structures: 2D Character Array (char[][])
• Programming Principles: Separation of Concerns, Defensive Programming, DRY (Don't Repeat Yourself)
• Game Logic: Boundary Validation, Mathematical Index Mapping, Symbol Assignment
• Version Control: Strict Gitflow Branching Strategy (Main ➔ Feature Branches per UC)

---

📁 Repository Structure

console-tictactoe-java/
│
├── TicTacToe.java       ← Single class containing all 5 UC implementations
└── README.md            ← You are here

---

💻 How to Run Locally

Want to play it yourself? Follow these steps:

1. Clone the repository:

git clone https://github.com/YOUR_USERNAME/console-tictactoe-java.git
cd console-tictactoe-java

2. Compile the Java file:

javac TicTacToe.java

3. Run the program:

java TicTacToe

✅ No external dependencies. Plain Java — runs anywhere with JDK 8+.

---

🌿 Gitflow Branch Strategy

main
 └── uc1-display-board
 └── uc2-toss-assign-symbols
 └── uc3-accept-user-input
 └── uc4-slot-to-board-index
 └── uc5-validate-move

Each branch represents one completed Use Case. Branches build upon each other sequentially, and the final uc5-validate-move branch is merged back into main as the complete working game foundation.

---

📐 Slot-to-Board Mapping Reference

Slot Numbers (user view)       Board Indices (system view)
┌───┬───┬───┐                  ┌──────────┬──────────┬──────────┐
│ 1 │ 2 │ 3 │                  │ [0][0]   │ [0][1]   │ [0][2]   │
├───┼───┼───┤       ──▶        ├──────────┼──────────┼──────────┤
│ 4 │ 5 │ 6 │                  │ [1][0]   │ [1][1]   │ [1][2]   │
├───┼───┼───┤                  ├──────────┼──────────┼──────────┤
│ 7 │ 8 │ 9 │                  │ [2][0]   │ [2][1]   │ [2][2]   │
└───┴───┴───┘                  └──────────┴──────────┴──────────┘

Formula:  row = (slot - 1) / 3
          col = (slot - 1) % 3

---

🚀 What's Next (Beyond UC5)

These Use Cases lay the groundwork for a fully playable game. Future extensions could include:

• ✅ UC6 — Computer AI move (random or strategic)
• ✅ UC7 — Check for Win / Draw condition
• ✅ UC8 — Full game loop with replay option

---

Made with ☕ Java and 💡 logic - one Use Case at a time.