Java Swing is often overlooked for game development — but when used with good architecture patterns like MVC and TDD, it can be a powerful tool.

In this post, I’ll explain how I built a modular, extensible Dungeon Maze Game using pure Java Swing and share tips for designing maintainable, testable desktop applications.

Why Java Swing for a Game?

Java Swing provides a robust and flexible UI toolkit.

However, it's not a game engine — so to build games with Swing, you have to:

  • Handle game loops, redraw cycles, and user input manually
  • Create a clean separation between game logic and UI rendering
  • Solve challenges related to real-time responsiveness

This made Swing an interesting challenge — and a perfect playground to apply software engineering principles like MVC architecture and Test-Driven Development. Java being a language that I have been using for a while it is easy to learn and apply this framework.

About the Project: Java Swing Dungeon Maze Game

The project is a grid-based dungeon crawler where:

  • The player navigates caves and tunnels
  • Encounters obstacles
  • Solves mazes generated randomly
  • Moves using keyboard input (Arrow keys)

The game architecture is designed to be extensible, testable, and easy to modify.

You can find the full code here: GitHub Repository

Key Architectural Decisions

🧩 Model-View-Controller (MVC)

Following MVC was critical:

  • Model: Game logic — player movement, maze generation, obstacles
  • View: The Swing GamePanel — renders the maze, player, and tiles
  • Controller: Handles keyboard input and updates the model

Example:

Handling player movement through the GameController:

case KeyEvent.VK_UP -> model.movePlayer(Direction.NORTH);
case KeyEvent.VK_DOWN -> model.movePlayer(Direction.SOUTH);

The GamePanel listens to the controller and updates the visual state accordingly.

One of the unique propositions of this application is that we are updating 2 major views, the top-down view and the first-person view. This concept can be used to create complex game elements like Heads-up-displays, Race Maps, etc.

🧪 Test-Driven Development (TDD)

The project is equipped with JUnit 5 tests covering the core game logic:

  • Player movement
  • Maze generation
  • Tile obstacle placement

Example: Testing if player movement respects walls:

@Test
void testPlayerCannotWalkThroughWalls() {
    Player player = new Player(startLocation);
    Maze maze = new Maze(5, 5);
    assertFalse(player.move(Direction.NORTH, maze)); // Assuming wall exists
}

Having tests made it easy to refactor or add new features without fear of breaking existing logic.

🎲 Randomized Maze Generation

One fun challenge was making the maze always connected but still random. I have used Kruskal's algorithm for the generation of the maze, which ensures generating unique mazes each time, and also that each location is reachable from every location.

To make the game more interesting, it is important to have a certain distance between the finish location and the player's spawn location. This is ensured by BFS, where the player is not "randomly" spawned but rather backtracked from the finish location and placed at n steps away.

I encapsulated random logic inside a dedicated class:

public class RandomGenerator {
    private final Random random = new Random();
    public int nextInt(int bound) {
        return random.nextInt(bound);
    }
}

This makes the randomness easily mockable for unit testing!

🖼️ Swing Graphics Rendering

The GamePanel is where the game world comes alive:

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    maze.draw(g, TILE_SIZE);
    player.draw(g, TILE_SIZE);
}

Each game tick:

  • Clears the panel
  • Redraws the maze
  • Redraws the player
  • Redraws obstacles or items

This manual cycle makes sure the UI stays responsive.

Challenges Faced 💡

  • Managing real-time updates without a game engine
  • Designing reusable components while working within Swing's event-driven model
  • Balancing testability with performance (e.g., avoiding unnecessary redraws)

Each challenge forced me to think like a software engineer, not just a game developer.

How You Can Use This Template

Because the project is built modularly, you can easily extend it:

  • Add new enemy types
  • Create different dungeon themes
  • Add player inventory, health bars, and abilities
  • Experiment with different maze generation algorithms

Check out the repo if you want to fork and create your own dungeon adventure!

Conclusion 🏁

Building a complex, polished game without a "game engine" using Java Swing was a rewarding experience.

It helped me:

  • Sharpen my understanding of MVC
  • Deepen my appreciation for TDD
  • Create a reusable framework for future Java-based games

If you're looking to solidify your Java skills, I highly recommend trying a Swing-based project yourself!

Feel free to fork Java Swing Dungeon Game and build something amazing. 🚀

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