Board.java

package com.packtpub.storm.model;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class Board implements Serializable {
    private static final long serialVersionUID = 1L;
    public static final String EMPTY = " ";
    public String[][] board = {{EMPTY, EMPTY, EMPTY}, {EMPTY, EMPTY, EMPTY}, {EMPTY, EMPTY, EMPTY}};

    public Board() {
    }

    public Board(String key) {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                this.board[i][j] = "" + key.charAt(i * 3 + j);
            }
        }
    }

    public List<Board> nextBoards(String player) {
        List<Board> boards = new ArrayList<Board>();
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (board[i][j].equals(EMPTY)) {
                    Board newBoard = this.clone();
                    newBoard.board[i][j] = player;
                    boards.add(newBoard);
                }
            }
        }
        return boards;
    }

    public boolean isEndState() {
        return (nextBoards("X").size() == 0 || Math.abs(score("X")) > 1000);
    }

    public int score(String player) {
        return scoreLines(player) - scoreLines(Player.next(player));
    }

    public int scoreLines(String player) {
        int score = 0;
        // Columns
        score += scoreLine(board[0][0], board[1][0], board[2][0], player);
        score += scoreLine(board[0][1], board[1][1], board[2][1], player);
        score += scoreLine(board[0][2], board[1][2], board[2][2], player);

        // Rows
        score += scoreLine(board[0][0], board[0][1], board[0][2], player);
        score += scoreLine(board[1][0], board[1][1], board[1][2], player);
        score += scoreLine(board[2][0], board[2][1], board[2][2], player);

        // Diagonals
        score += scoreLine(board[0][0], board[1][1], board[2][2], player);
        score += scoreLine(board[2][0], board[1][1], board[0][2], player);
        return score;
    }

    public int scoreLine(String pos1, String pos2, String pos3, String player) {
        int score = 0;
        if (pos1.equals(player) && pos2.equals(player) && pos3.equals(player)) {
            score = 10000;
        } else if (pos1.equals(player) && pos2.equals(player) && pos3.equals(EMPTY) ||
                pos1.equals(EMPTY) && pos2.equals(player) && pos3.equals(player)) {
            score = 100;
        } else {
            if (pos1.equals(player) && pos2.equals(EMPTY) && pos3.equals(EMPTY) ||
                    pos1.equals(EMPTY) && pos2.equals(player) && pos3.equals(EMPTY) ||
                    pos1.equals(EMPTY) && pos2.equals(EMPTY) && pos3.equals(player)) {
                score = 10;
            }
        }
        return score;
    }

    public Board clone() {
        Board clone = new Board();
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                clone.board[i][j] = this.board[i][j];
            }
        }
        return clone;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder("\n---------\n");
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                sb.append("|").append(board[i][j]).append("|");
            }
            sb.append("\n---------\n");
        }
        return sb.toString();
    }

    public String toKey() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                sb.append(board[i][j]);
            }
        }
        return sb.toString();
    }
}