Review of Major SE1021 Topics

In this sequence of tutorial pages we will be creating a game similar to the Blocks Mania iOS game.

Game Introduction (VIDEO)

The game consists of a tiled game board like the one shown below:

We will begin with a very simple game board that consists of blank tiles ( / ), the player ( / @), and the end point ( / X):

 0123456789
0          
1 X       @
2          
3          
4          

Tile and Position Classes (VIDEO)

We will represent each spot on the gameboard with a tile. Each tile is a button that can be pressed by clicking with the mouse. Each tile keeps track of a position (column and row) and a type. What follows is a first attempt at these classes.

public class Position {

	public final int col;
	public final int row;
	
	public Position(int col, int row) {
		this.col = col;
		this.row = row;
	}
}

Since the Position class just describes the pairing of integers, I've made the attributes public. Note also that I've declared the attributes as final.

public class Tile extends JButton {

	private final Position position;
	private final char type;
	
	public Tile(Position position) {
		this(position, ' ');
	}

	public Tile(Position position, char type) {
		super("" + type);
		this.position = position;
		this.type = type;
	}
}

The type attribute is used to distinguish between different types of game tiles. In the beginning stages of our development, this type will just be a character that will be displayed as the label for the button.

QUESTIONS/EXERCISES

1. What are the advantages of declaring the Position attributes as public?
2. What are the disadvantages of declaring the Position attributes as public?
3. Since the type will be the same for every object from the Tile class, can you think of a better way to store this information?

Game Movement (VIDEO)

The video describes the intended behavior when the player makes a move. If the tile at row: 1, col: 3 is clicked, the tile at row: 1, col: 8 should determine what should happen next. If this tile is a blank tile, then the Player should be moved to position row: 1, col: 8, and the next move should be moved based on the tile at position row: 1, col: 7.

 0123456789
0          
1 X       @
2          
3          
4          

Therefore, we add the following method to the Tile class:

public class Tile extends JButton {
	// ...	
	public Move processMove(Move move) {
		return move;
	}
}

The Move class keeps track of the current position and direction that the Player is moving. The direction is defined as one of a number of class constants:

public class Move {
	public final static int DIRECTION_NORTH = 0;
	public final static int DIRECTION_SOUTH = 1;
	public final static int DIRECTION_WEST = 2;
	public final static int DIRECTION_EAST = 3;
	public final static int DIRECTION_STOP = 4;
	public final static int DIRECTION_WIN = 5;
	public final static int DIRECTION_LOSE = 6;
	
	private final int direction;
	private final Position position;
	
	public Move(int direction, Position position) {
		this.direction = direction;
		this.position = position;
	}
	
	public int getDirection() {
		return direction;
	}
	
	public Position getPosition() {
		return position;
	}

}

QUESTIONS/EXERCISES

1. Which class constant directions are not required to implement the Tile.processMove() method?
2. Implement the processMove() method for the Tile class that represents a blank tile.
3. The position and direction attributes are declared final. What implications does this have on how objects from the Move class can be used?

Gameboard Class (VIDEO)

A GameBoard class is used to manage the GUI of each level of the game. The GameBoard is a JPanel that contains a grid of buttons.

public class GameBoard extends JPanel {
	
	private Tile[][] gameboard;
	
	public GameBoard(String filename) {
		loadGame(filename);
		createGUI();
	}

	private void createGUI() {
		// Use GridLayout
		// Add tiles to JPanel
	}

	private void loadLevel(String filename) {
		// Read in characters from file
		// Allocate space for gameboard 2D array
		// Create tiles from characters
		// Add tiles to gameboard
		// Connect action listener to each tile
	}
}

QUESTIONS/EXERCISES

1. Implement the loadLevel() method for the GameBoard class.
2. Implement the createGUI() method for the GameBoard class.

Game and WinTile Classes (VIDEO)

For now, the Game class will just create a game using the first level of the game. Eventually it will need to manage multiple levels and the transition between levels.

public class Game extends JFrame {

	public static void main(String[] ignored) {
		JFrame game = new Game();
		game.setVisible(true);
	}
	
	public Game() {
		super("Maniacal Blocks");
		this.setSize(300, 200);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
		add(new GameBoard("levels/level1.txt"));
	}
}

public class WinTile extends Tile {

	public WinTile(Position position) {
		super(position, 'X');
	}
	
	@Override
	public Move processMove(Move move) {
		return move;
	}
}

QUESTIONS/EXERCISES

1. The EndTile class in the video has been renamed WinTile here. Why?
2. Implement the processMove() method for the WinTile class.
3. Modify the Game class to add a panel that shows the number of moves made and contains a RESTART button.