tic tac toe

import java.util.Scanner;

/*
 * A console version of tic-tac-toe.
 * KNOWN ISSUES:
 *  -Instead of deciding who is X and who is O,
 *   the logic decides whether X goes first or O goes first.
 *   This issue was noticed too late to fix, so I left it. :P
 *   Player 1 is always X and player 2 is always O, regardless
 *   of who goes first.
 */
public class TicTacToe {
    //class members
    static Scanner input = new Scanner(System.in);
    static String player1, player2;
    static char[][] board = new char[3][3];
    static boolean p1Plays;
    static boolean p1Wins, p2Wins;

    public static void main(String[] args) {
        int x, y;
        int guessP1, guessP2;

        //player1 setup
        System.out.print("X, enter your name: ");
        player1 = input.next();

        do {
            System.out.printf("%s, enter a number between 0 and 9: ", player1);
            guessP1 = input.nextInt();
            if(guessP1 > 9 || guessP1 < 0)
                System.out.println("Your guess is out of range!");
        } while(guessP1 > 9 || guessP1 < 0);
        System.out.println("");

        //player2 setup
        //they get checks and things to be sure they don't pick same as P1
        do {
            System.out.print("O, enter your name: ");
            player2 = input.next();
            if(player1.equals(player2))
                System.out.println("That name is taken.");
        } while(player1.equals(player2));

        do {
            System.out.printf("%s, enter a number between 0 and 9: ", player2);
            guessP2 = input.nextInt();
            if(guessP1 == guessP2)
                System.out.printf("%s already picked %d!\n", player1, guessP2);
            if(guessP2 > 9 || guessP2 < 0)
                System.out.println("Your guess is out of range!");
        } while(guessP1 == guessP2 || guessP2 > 9 || guessP2 < 0);
        System.out.println("");

        //decision time!
        p1Plays = decideIfP1GoesFirst(guessP1, guessP2);

        if(p1Plays)
            System.out.printf("%s goes first.", player1);
        else
            System.out.printf("%s goes first.", player2);

        //start game!
        for(y = 0; y < 3; y++) {
            for(x = 0; x < 3; x++)
                board[y][x] = ' ';
        }

        gameLoop();
    }

    //choose whether or not P1 goes first
    public static boolean decideIfP1GoesFirst(int guess1, int guess2) {
        int rando = (int)(Math.random() * 10.0);

        System.out.printf("Random number: %d\n", rando);
        return Math.abs(guess1 - rando) < Math.abs(guess2 - rando);
    }

    //print the game board
    public static void printBoard() {
        int x, y;
        System.out.printf("%s is X.\n%s is O.\n\n", player1, player2);
        System.out.println("  A B C");
        for(y = 0; y < 3; y++) {
            System.out.printf("%d ", y + 1);
            for(x = 0; x < 3; x++) {
                System.out.printf("%1c", board[y][x]);
                if(x != 2) System.out.print("|");
            }
            if(y != 2) System.out.print("\n  -+-+-");
            System.out.println("");
        }
    }

    //the core game loop
    public static void gameLoop() {
        boolean isValidMove;
        String move;

        while(!p1Wins && !p2Wins) {
            //clear screen; this is the only way that seems to work
            System.out.println("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
            //print board
            printBoard();

           //is the board full?
            if(boardIsFull()) {
                System.out.println("\nBoard is full!\nGame over.");
                break;
            }

            //ask for move
            isValidMove = false;
            do {
                //input prompt
                System.out.println();
                if(p1Plays)
                    System.out.printf("%s, where are you going to play? (ex. A1) ", player1);
                else
                    System.out.printf("%s, where are you going to play? (ex. A1) ", player2);

                move = input.next().toUpperCase();

                //set the board!
                if(setBoard(move)) isValidMove = true;

            } while(!isValidMove);

            //loop back, switch players
            p1Plays = !p1Plays;
        }
    }

    //test if the board is full
    public static boolean boardIsFull() {
        int y, x;
        for(y= 0; y < 3; y++) {
            for(x = 0; x < 3; x++){
                if(board[y][x] == ' ') return false;
            }
        }
        return true;
    }

    //make the move, but ONLY if it is valid
    public static boolean setBoard(String move) {
        int y, x;
        //this set of switches tests input integrity
        //check row
        switch(move.charAt(0)) {
        case 'A':
            x = 0;
            break;
        case 'B':
            x = 1;
            break;
        case 'C':
            x = 2;
            break;
        default:
            System.out.println("Input is invalid!");
            return false;
        }
        //check column
        switch(move.charAt(1)) {
        case '1':
            y = 0;
            break;
        case '2':
            y = 1;
            break;
        case '3':
            y = 2;
            break;
        default:
            System.out.println("Input is invalid!");
            return false;
        }

        //see if the space is taken
        if(board[y][x] != ' ') {
            System.out.println("This space is taken!");
            return false;
        }

        //place in board
        if(p1Plays) board[y][x] = 'X';
        else board[y][x] = 'O';

        return true;
    }
}