Java/TicTacToe.java

import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.util.Scanner;
import java.util.Random;

public class TicTacToe {
    private static ArrayList<String> freeSpaces;
    private static Map<String, String> fullBoard;
    private static Scanner input;

   private static String player() {
        while(true){
            System.out.println(String.format("Make your move. Valid moves: {0}", freeSpaces));
            String move = input.nextLine();
            if (freeSpaces.contains(move)) {
                return move;
            } else {
                System.out.println("The move you entered is not valid. Please enter a valid move.");
            }
        }
    }

    private static String ai() {
        int rnd = new Random().nextInt(freeSpaces.size());
        String[] tmpFreeSpaces = freeSpaces.toArray(new String[0]);
        String move = tmpFreeSpaces[rnd];
        System.out.println(move);
        return move;
    }

    private static void handle(String playing, String move) {
        switch (playing) {
            case "player":
                fullBoard.put(move, "X");
                freeSpaces.remove(move);
                break;
            case "ai":
                fullBoard.put(move, "O");
                freeSpaces.remove(move);
                break;
        }
    }


    private static boolean checkForDraw() {
        if (freeSpaces.size() == 0) {
            return true;
        } else {
            return false;
        }
    }

    private static String checkForWin() {
        String a1Value = fullBoard.get("a1");
        String a2Value = fullBoard.get("a2");
        String a3Value = fullBoard.get("a3");
        String b1Value = fullBoard.get("b1");
        String b2Value = fullBoard.get("b2");
        String b3Value = fullBoard.get("b3");
        String c1Value = fullBoard.get("c1");
        String c2Value = fullBoard.get("c2");
        String c3Value = fullBoard.get("c3");

        if (a1Value.equals("X") && a2Value.equals("X") && a3Value.equals("X")) {
            return "player";
        } else if (b1Value.equals("X") && b2Value.equals("X") && b3Value.equals("X")) {
            return "player";
        } else if (c1Value.equals("X") && c2Value.equals("X") && c3Value.equals("X")) {
            return "player";
        } else if (a1Value.equals("X") && b1Value.equals("X") && c1Value.equals("X")) {
            return "player";
        } else if (a2Value.equals("X") && b2Value.equals("X") && c2Value.equals("X")) {
            return "player";
        } else if (a3Value.equals("X") && b3Value.equals("X") && c3Value.equals("X")) {
            return "player";
        } else if (a1Value.equals("X") && b2Value.equals("X") && c3Value.equals("X")) {
            return "player";
        } else if (a3Value.equals("X") && b2Value.equals("X") && c1Value.equals("X")) {
            return "player";
        }

        if (a1Value.equals("O") && a2Value.equals("O") && a3Value.equals("O")) {
            return "ai";
        } else if (b1Value.equals("O") && b2Value.equals("O") && b3Value.equals("O")) {
            return "ai";
        } else if (c1Value.equals("O") && c2Value.equals("O") && c3Value.equals("O")) {
            return "ai";
        } else if (a1Value.equals("O") && b1Value.equals("O") && c1Value.equals("O")) {
            return "ai";
        } else if (a2Value.equals("O") && b2Value.equals("O") && c2Value.equals("O")) {
            return "ai";
        } else if (a3Value.equals("O") && b3Value.equals("O") && c3Value.equals("O")) {
            return "ai";
        } else if (a1Value.equals("O") && b2Value.equals("O") && c3Value.equals("O")) {
            return "ai";
        } else if (a3Value.equals("O") && b2Value.equals("O") && c1Value.equals("O")) {
            return "ai";
        }

        if (checkForDraw()){
            return "draw";
        }

        return "none";
    }

    private static void showBoard() {
        String a1Value = fullBoard.get("a1");
        String a2Value = fullBoard.get("a2");
        String a3Value = fullBoard.get("a3");
        String b1Value = fullBoard.get("b1");
        String b2Value = fullBoard.get("b2");
        String b3Value = fullBoard.get("b3");
        String c1Value = fullBoard.get("c1");
        String c2Value = fullBoard.get("c2");
        String c3Value = fullBoard.get("c3");
        System.out.println("___1___2___3__");
        System.out.printf("a| %s | %s | %s |\n", a1Value, a2Value, a3Value);
        System.out.printf("b| %s | %s | %s |\n", b1Value, b2Value, b3Value);
        System.out.printf("c| %s | %s | %s |\n", c1Value, c2Value, c3Value);
        System.out.println("______________");
    }

    private static boolean processWin(String status) {
        switch (status) {
            case "player":
                System.out.println("You have won! GG!");
                showBoard();
                return true;
            case "ai":
                System.out.println("You have lost against an AI that makes random moves. Shameful.");
                showBoard();
                return true;
            case "draw":
                System.out.println("It's a draw!");
                showBoard();
                return true;
            default:
                return false;
        }
    }

// __a___b___c__
//1| X | O | O |
// _____________
//2| O | X | X |
// _____________
//3| O | X | X |
// _____________

    public static void trueMain() {
        while(true) {
            showBoard();
            handle("player", player());
            if (processWin(checkForWin())) {
                    break;
            }

            showBoard();
            handle("ai", ai());
            if (processWin(checkForWin())) {
                    break;
            }
        }
    }

    public static void main(String args[]) {
        fullBoard = new HashMap<>();
        freeSpaces = new ArrayList<>();
        input = new Scanner(System.in);
        fullBoard.put("a1", " ");
        fullBoard.put("a2", " ");
        fullBoard.put("a3", " ");
        fullBoard.put("b1", " ");
        fullBoard.put("b2", " ");
        fullBoard.put("b3", " ");
        fullBoard.put("c1", " ");
        fullBoard.put("c2", " ");
        fullBoard.put("c3", " ");
        fullBoard.put("a1", " ");
        freeSpaces.add("a1");
        freeSpaces.add("a2");
        freeSpaces.add("a3");
        freeSpaces.add("b1");
        freeSpaces.add("b2");
        freeSpaces.add("b3");
        freeSpaces.add("c1");
        freeSpaces.add("c2");
        freeSpaces.add("c3");
        trueMain();
    }
}