Question

Develop a very simple Tic Tac Toe gaming software in Java. If you want, you may take some code (with proper reference to the source from where it is taken - i.e., hackerrank or github) from an existing game implementation to extend/improve the functionalities. To develop a good quality software, you would like to follow a particular software engineering process or more than one process (waterfall, incremental, agile etc.) and choose an appropriate programming language.

Answer 1

import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.Scanner;

/**
*
* @author MeneXia (Xavi Ablaza)
*
*/
public class TicTacToe {
   static Scanner in;
   static String[] board;
   static String turn;

   public static void main(String[] args) {
       in = new Scanner(System.in);
       board = new String[9];
       turn = "X";
       String winner = null;
       populateEmptyBoard();

       System.out.println("Welcome to 2 Player Tic Tac Toe.");
       System.out.println("--------------------------------");
       printBoard();
       System.out.println("X's will play first. Enter a slot number to place X in:");

       while (winner == null) {
           int numInput;
           try {
               numInput = in.nextInt();
               if (!(numInput > 0 && numInput <= 9)) {
                   System.out.println("Invalid input; re-enter slot number:");
                   continue;
               }
           } catch (InputMismatchException e) {
               System.out.println("Invalid input; re-enter slot number:");
               continue;
           }
           if (board[numInput-1].equals(String.valueOf(numInput))) {
               board[numInput-1] = turn;
               if (turn.equals("X")) {
                   turn = "O";
               } else {
                   turn = "X";
               }
               printBoard();
               winner = checkWinner();
           } else {
               System.out.println("Slot already taken; re-enter slot number:");
               continue;
           }
       }
       if (winner.equalsIgnoreCase("draw")) {
           System.out.println("It's a draw! Thanks for playing.");
       } else {
           System.out.println("Congratulations! " + winner + "'s have won! Thanks for playing.");
       }
   }

   static String checkWinner() {
       for (int a = 0; a < 8; a++) {
           String line = null;
           switch (a) {
           case 0:
               line = board[0] + board[1] + board[2];
               break;
           case 1:
               line = board[3] + board[4] + board[5];
               break;
           case 2:
               line = board[6] + board[7] + board[8];
               break;
           case 3:
               line = board[0] + board[3] + board[6];
               break;
           case 4:
               line = board[1] + board[4] + board[7];
               break;
           case 5:
               line = board[2] + board[5] + board[8];
               break;
           case 6:
               line = board[0] + board[4] + board[8];
               break;
           case 7:
               line = board[2] + board[4] + board[6];
               break;
           }
           if (line.equals("XXX")) {
               return "X";
           } else if (line.equals("OOO")) {
               return "O";
           }
       }

       for (int a = 0; a < 9; a++) {
           if (Arrays.asList(board).contains(String.valueOf(a+1))) {
               break;
           }
           else if (a == 8) return "draw";
       }

       System.out.println(turn + "'s turn; enter a slot number to place " + turn + " in:");
       return null;
   }

   static void printBoard() {
       System.out.println("/---|---|---\\");
       System.out.println("| " + board[0] + " | " + board[1] + " | " + board[2] + " |");
       System.out.println("|-----------|");
       System.out.println("| " + board[3] + " | " + board[4] + " | " + board[5] + " |");
       System.out.println("|-----------|");
       System.out.println("| " + board[6] + " | " + board[7] + " | " + board[8] + " |");
       System.out.println("/---|---|---\\");
   }

   static void populateEmptyBoard() {
       for (int a = 0; a < 9; a++) {
           board[a] = String.valueOf(a+1);
       }
   }
}