main.java

import java.util.Scanner;
import java.util.Random;
public class main {

    static int occu = 0;
    static boolean gameEnd = false;

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.println("Choose an option:\n1. 1v1\n2. You vs Computer");
        int isComp = s.nextInt();
        clearScreen();
        String[] board = {"_", "_", "_", "_", "_", "_", "_", "_", "_"};
                    
        //print board;
        printboard(board);
        while (!gameEnd) {
            takeTurn(1, "O", board, s,0);
            if (gameEnd) break;
            takeTurn(2, "X", board, s, isComp);
        }
        s.close();
        cheackwin(board);
        System.out.println("\n\nGame Over!");

    }
    
    static void printboard(String[] board){
        for (int i = 0; i <= 8; i++) {
            System.out.print("| " + board[i] + " ");
            if (i == 2 | i == 5 | i == 8) {
                System.out.print("|");
                System.out.println("");
            }
        }
    }

    static void cheackwin(String[] c) {
        String winner = win(c);
        if (winner.equals("O")) {
            System.out.println("\nPlayer 1 won");
            gameEnd = true;
        }
        if (winner.equals("X")) {
            System.out.println("\nPlayer 2 won");
            gameEnd = true;
        }
        if (winner.equals("D") && occu == 9) {
            System.out.println("\nDraw");
            gameEnd = true;
        }
    }

    static String win(String[] b) {
        if (b[0].equals(b[1]) && b[1].equals(b[2])) {
            return b[0];
        }
        if (b[3].equals(b[4]) && b[4].equals(b[5])) {
            return b[3];
        }
        if (b[6].equals(b[7]) && b[7].equals(b[8])) {
            return b[6];
        }

        if (b[0].equals(b[3]) && b[3].equals(b[6])) {
            return b[0];
        }
        if (b[1].equals(b[4]) && b[4].equals(b[7])) {
            return b[1];
        }
        if (b[2].equals(b[5]) && b[5].equals(b[8])) {
            return b[2];
        }

        if (b[0].equals(b[4]) && b[4].equals(b[8])) {
            return b[0];
        }
        if (b[2].equals(b[4]) && b[4].equals(b[6])) {
            return b[2];
        }

        return "D";
    }
    public static void takeTurn(int player, String symbol, String[] board, Scanner s, int isComp) {
        boolean valid = false;
        int pos;
        while (!valid && !gameEnd) {
            if (isComp == 2) {
                System.out.print("Computer pos: ");
                Random rand = new Random();
                pos = rand.nextInt(9) + 1; 
            }
            else {
                System.out.print("Player " + player + " pos: ");
                pos = s.nextInt();
            }

            if (board[pos - 1].equals("_")) {
                valid = true;
                board[pos - 1] = symbol;
                occu++;
                cheackwin(board);
                clearScreen();
                printboard(board);
            } else {
                clearScreen();
                System.out.println("Invalid pos, try again: ");
                printboard(board);
            }
        }
}


    public final static void clearScreen() {
        try {
            final String os = System.getProperty("os.name").toLowerCase();
            ProcessBuilder pb;

            if (os.contains("windows")) {
                pb = new ProcessBuilder("cmd", "/c", "cls");
            } else {
                pb = new ProcessBuilder("clear");
            }

            pb.inheritIO().start().waitFor();
        } catch (final Exception e) {
            System.err.println("Error clearing console: " + e.getMessage());
        }
    }
}