My implementation of the classic Xs and Os game (stage 5/5 of Tic-Tac-Toe project from Jet Brains Academy).

The example below shows how program works.

Notice that after Enter the coordinates: comes the user input.

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My code:

import java.util.Scanner;

public class Main { static Scanner scan = new Scanner(System.in); static boolean isXyValid = false; static int move = 1; static String signal; static int x = 0, y = 0; static boolean isGameOver = false; static String[][] gameField = new String[3][3];

public static void main(String[] args) {
    initializeGameField();
    printGameField();
    playGame();
}

public static void initializeGameField() {
    for (int i = 0; i < 9; i++) {
        gameField[i / 3][i % 3] = " ";
    }
}

public static void printGameField() {
    System.out.println("---------");
    for (int i = 0; i < gameField.length; i++) {
        System.out.printf("| %s %s %s |\n", gameField[i][0], gameField[i][1], gameField[i][2]);
    }
    System.out.println("---------");
}

public static void playGame() {

    while (!isXyValid) {
        while (!isGameOver) {
            if (move % 2 == 1) { // player 'X'
                signal = "X";
            } else {            // player 'O'
                signal = "O";
            }
            System.out.println("Enter the coordinates: ");
            try {
                int xy = Integer.parseInt(scan.nextLine().replace(" ", ""));
                x = xy / 10;
                y = xy % 10;
                if (x > 3 || y > 3) {
                    System.out.println("Coordinates should be from 1 to 3!");
                } else if (x >= 1 || y >= 1) {
                    if (!gameField[-y + 3][x - 1].equals(" ")) {
                        System.out.println("This cell is occupied! Choose another one!");
                    } else {
                        gameField[-y + 3][x - 1] = signal;
                        printGameField();
                        isGameOver = checkGame();
                        move++;
                        isXyValid = true;
                    }
                }
            } catch (NumberFormatException e) {
                System.out.println("You should enter numbers!");
            }
        }

    }
    scan.close();
}

public static boolean checkGame() {
    if (gameField[0][0].equals("X") && gameField[0][1].equals("X") && gameField[0][2].equals("X") ||
            gameField[1][0].equals("X") && gameField[1][1].equals("X") && gameField[1][2].equals("X") ||
            gameField[2][0].equals("X") && gameField[2][1].equals("X") && gameField[2][2].equals("X") ||
            gameField[0][0].equals("X") && gameField[1][0].equals("X") && gameField[2][0].equals("X") ||
            gameField[0][1].equals("X") && gameField[1][1].equals("X") && gameField[2][1].equals("X") ||
            gameField[0][2].equals("X") && gameField[1][2].equals("X") && gameField[2][2].equals("X") ||
            gameField[0][0].equals("X") && gameField[1][1].equals("X") && gameField[2][2].equals("X") ||
            gameField[2][0].equals("X") && gameField[1][1].equals("X") && gameField[0][2].equals("X")) {
        System.out.println("X wins");
        return true;
    } else if (gameField[0][0].equals("O") && gameField[0][1].equals("O") && gameField[0][2].equals("O") ||
            gameField[1][0].equals("O") && gameField[1][1].equals("O") && gameField[1][2].equals("O") ||
            gameField[2][0].equals("O") && gameField[2][1].equals("O") && gameField[2][2].equals("O") ||
            gameField[0][0].equals("O") && gameField[1][0].equals("O") && gameField[2][0].equals("O") ||
            gameField[0][1].equals("O") && gameField[1][1].equals("O") && gameField[2][1].equals("O") ||
            gameField[0][2].equals("O") && gameField[1][2].equals("O") && gameField[2][2].equals("O") ||
            gameField[0][0].equals("O") && gameField[1][1].equals("O") && gameField[2][2].equals("O") ||
            gameField[2][0].equals("O") && gameField[1][1].equals("O") && gameField[0][2].equals("O")) {
        System.out.println("O wins");
        return true;
    } else if (move == 9) {
        System.out.println("Draw");
        return true;
    }
    return false;
}

}