ConnectFourI.java

import java.util.Arrays;
import java.util.Scanner;
import java.util.Stack;

public abstract class ConnectFourI {
	protected int BOARD_HEIGHT = 6;
	protected int BOARD_WIDTH = 7;
	protected Player[][] board = new Player[BOARD_HEIGHT][BOARD_WIDTH];
	protected Player x; // The player who moves first
	protected Player o; // The player who moves second
	protected Player toMove; // The player whose turn it is to move

	/**
	 * @return the board width
	 */
	public int getWidth() {
		return BOARD_WIDTH;
	}

	/**
	 * @return the board height
	 */
	public int getHeight() {
		return BOARD_HEIGHT;
	}

	/**
	 * @return columns representing legal moves.
	 */
	public abstract int[] getMoves();

	/**
	 * @return whether or not the game is over
	 */
	public abstract boolean isGameOver();

	/**
	 * @return a winner, if there is one, otherwise null
	 */
	public abstract Player getWinner();

	/**
	 * Makes a move for the current player to move.
	 * 
	 * @param col
	 * @return true if the move was played, false otherwise
	 */
	public abstract boolean makeMove(int col);

	/**
	 * Undoes the last move
	 */
	public abstract void undoMove();

	/**
	 * @param row
	 * @param col
	 * @return the player who owns the piece at (row, col)
	 */
	public abstract Player getSquare(int row, int col);

	/**
	 * Sets the state of the board given a string of (e.g. 'x', 'o', and ' ') in
	 * row-major order. Treats invalid characters as spaces and ignores excess
	 * characters.
	 * 
	 * @param state
	 * @throws IllegalArgumentException
	 *             if (num(x) - num(o)) not in {0, 1}
	 */
	public void setState(String state) {
		int counter = 0;
		int size = BOARD_WIDTH * BOARD_HEIGHT;
		this.board = new Player[BOARD_HEIGHT][BOARD_WIDTH];
		for (int i = 0; i < size; i++) {
			char sq = state.charAt(i);
			if (x.getName().equals(sq)) {
				counter++;
				this.board[i / BOARD_WIDTH][i % BOARD_WIDTH] = x;
			} else if (o.getName().equals(sq)) {
				counter--;
				this.board[i / BOARD_WIDTH][i % BOARD_WIDTH] = o;
			}
		}
		if (counter == 1) {
			this.toMove = x;
		}
		if (counter == 0) {
			this.toMove = o;
		} else
			throw new IllegalArgumentException();
	}

	/*
	 * Returns the string representation of the board state in row-major order,
	 * using 'x', 'o', and ' ' characters. (non-Javadoc)
	 * 
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < BOARD_HEIGHT; i++) {
			for (int j = 0; j < BOARD_WIDTH; j++) {
				Player sq = this.board[i][j];
				if (sq != null) {
					sb.append(sq.toString());
				} else {
					sb.append(' ');
				}
			}
		}
		return sb.toString();
	}

	/**
	 * Prints the board.
	 */
	public void printBoard() {
		for (int i = 0; i < BOARD_HEIGHT; i++) {
			System.out.print('|');
			for (int j = 0; j < BOARD_WIDTH; j++) {
				Player sq = this.board[i][j];
				if (sq != null) {
					System.out.print(sq.toString() + "|");
				} else {
					System.out.print(" |");
				}
			}
			System.out.println();
		}
	}
	
	/**
	 * @return the player whose turn it is to move
	 */
	public abstract Player getToMove();
	
	public static void main(String[] args) {
		// just to play around with it...
		ConnectFourI cf = new ConnectFour();
		EvaluationI ev = new Evaluation(cf.x);
		AII ai = new AI(ev);
		Scanner scan = new Scanner(System.in);
			
		while (!cf.isGameOver()) {
			int move = ai.findMove(cf, 5);
			cf.makeMove(move);
			cf.printBoard();
			System.out.println(Arrays.toString(ev.nInARow(cf, 2)));
			if (cf.isGameOver())
				break;
			System.out.println("AI Move: " + move + " Your move? ");
			cf.printBoard();
			System.out.println(ev.evaluate(cf, 7));
			cf.makeMove(scan.nextInt());
		}
	}	
}