TicTacToe.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
//@JIGMECODES

public class TicTacToe {
	
	static ArrayList<Integer> playerPositions = new ArrayList<Integer>();
	static ArrayList<Integer> cpuPositions = new ArrayList<Integer>();
	
	public static void main(String[] args) {
		
		char[][] gameBoard = {{' ', '|', ' ', '|', ' '},
				              {'-', '+', '-', '+', '-'},
				              {' ', '|', ' ', '|', ' '},
				              {'-', '+', '-', '+', '-'},
				              {' ', '|', ' ', '|', ' '}};
		
		printGame(gameBoard);
	
		
		while(true) {
			Scanner scan = new Scanner(System.in);
			System.out.println("Enter a number from 1-9");
			int playerPos = scan.nextInt();
			while(playerPositions.contains(playerPos) || cpuPositions.contains(playerPositions)) {
				System.out.println("Error, enter different position");
				playerPos = scan.nextInt();
				
			}

			placePiece(gameBoard, playerPos, "player");
			
			String result = checkWinner();
			if(result.length() > 0) {
				System.out.println(result);
				break;
			}
			
			Random rand = new Random();
			int cpuPos = rand.nextInt(9) + 1;
			while(playerPositions.contains(cpuPos) || cpuPositions.contains(cpuPos)) {
				cpuPos = rand.nextInt(9) + 1;
		}
				
     placePiece(gameBoard, cpuPos, "cpu");
			
			printGame(gameBoard);
			
			result = checkWinner();
			if(result.length() > 0) {
				System.out.println(result);
				break;
			}
			
	}
		
}


public static void printGame(char[][] gameBoard) {
	for(char[] row : gameBoard) {
		for(char c : row) {
			System.out.print(c);
		}
		System.out.println();
	}
}

public static void placePiece(char[][] gameBoard, int pos, String user) {
	
	char symbol = ' ';
	
	if(user.equals("player")) {
		symbol = 'X';
		playerPositions.add(pos);
	}
		else if(user.equals("cpu")) {
			symbol = 'O';
			cpuPositions.add(pos);
	}
	
	switch(pos) {
		case 1: 
			gameBoard[0][0] = symbol;
			break;
		case 2: 
			gameBoard[0][2] = symbol;
			break;
		case 3: 
			gameBoard[0][4] = symbol;
			break;
		case 4: 
			gameBoard[2][0] = symbol;
			break;
		case 5: 
			gameBoard[2][2] = symbol;
			break;
		case 6: 
			gameBoard[2][4] = symbol;
			break;
		case 7: 
			gameBoard[4][0] = symbol;
			break;
		case 8: 
			gameBoard[4][2] = symbol;
			break;
		case 9: 
			gameBoard[4][4] = symbol;
			break;
		default:
			break;
			
		}
	}

public static  String checkWinner() {
	
	List topRow = Arrays.asList(1, 2, 3);
	List midRow = Arrays.asList(4, 5, 6);
	List botRow = Arrays.asList(7, 8, 9);
	List leftCol = Arrays.asList(1, 4, 7);
	List midCol = Arrays.asList(2, 5, 8);
	List rightCol = Arrays.asList(3, 6, 9);
	List cross1 = Arrays.asList(1, 5, 9);
	List cross2 = Arrays.asList(7, 5, 3);
	
	List<List> winning = new ArrayList<List>();
	winning.add(topRow);
	winning.add(midRow);
	winning.add(botRow);
	winning.add(leftCol);
	winning.add(midCol);
	winning.add(rightCol);
	winning.add(cross1);
	winning.add(cross2);
	
	for(List l : winning) {
		if(playerPositions.containsAll(l)) {
			return "YOU WON!";
		} else if(cpuPositions.containsAll(l)) {
			return ":( U LOST";
		} else if(playerPositions.size() + cpuPositions.size() == 9) {
			return "TIE";
		}
	}
	
	return "";
	}
}