TicTacToe 2.1

package tictactoe;

import java.util.*;

enum Player {
    HUMAN("X"),
    COMPUTER("O");

    private final String symbol;

    Player(String symbol) {
        this.symbol = symbol;
    }

    String getSymbol() {
        return symbol;
    }

}


public class TicTacToe {

    private final String[] grid = new String[9];
    private final Scanner input = new Scanner(System.in);

    public TicTacToe() {
        gameLoop();
    }

    private void gameLoop() {
        initializeGrid();

        while (hasWinner()) {
            runHumansTurn();
            if (isDraw()){
                System.out.println("DRAW");
                return;
            }
            runComputerTurn();
            displayGrid();
        }
        getWinner();
    }

    private void initializeGrid() {
        for (int i = 0; i < grid.length; i++) {
            grid[i] = String.valueOf(i + 1);
        }
    }

    private boolean hasWinner() {
        if (isWinner(Player.HUMAN.getSymbol())) {
            return false;
        } else return !isWinner(Player.COMPUTER.getSymbol());
    }

    private void runHumansTurn() {
        int human;
        System.out.println("Pick a number from 1 - 9 ");
        human = input.nextInt();
        while (isTileTaken(grid[human - 1])) {
            System.out.println("Try again that tile is taken");
            human = input.nextInt();
        }
        grid[human - 1] = Player.HUMAN.getSymbol();
    }

    private boolean isDraw() {
        return Arrays.stream(grid).distinct().count() == 2 && hasWinner();
    }

    private void runComputerTurn() {
        int computer;
        computer = (int) (Math.random() * 9 + 1);
        while (isTileTaken(grid[computer-1])) {
            computer = (int) (Math.random() * 9 + 1);
        }
        grid[computer-1] = Player.COMPUTER.getSymbol();
    }

    private void displayGrid() {
        for (int i = 0; i < grid.length; i++) {
            if(isLastRowIndex(i)) {
                System.out.print(grid[i] + "\n");
            }else {
                System.out.print(grid[i] + "|");
            }
        }
    }

    private void getWinner() {
        if(isWinner(Player.HUMAN.getSymbol())){
            System.out.println("Player won");
        }else{
            System.out.println("Computer won");
        }
    }

    private boolean isTileTaken(String playerTile) {
        return  playerTile.equals(Player.HUMAN.getSymbol()) || playerTile.equals(Player.COMPUTER.getSymbol());
    }

    private boolean isLastRowIndex(int index) {
        return index  == 2 || index == 5 || index == 8;
    }

    private boolean isWinner(String userCharacter) {
        return hasWonHorizontally(userCharacter)
                || hasWonVertically(userCharacter)
                || hasWonDiagonally(userCharacter);
    }

    private boolean hasWonDiagonally(String userCharacter) {
        return grid[0].equals(userCharacter) && grid[4].equals(userCharacter) && grid[8].equals(userCharacter)
                || grid[2].equals(userCharacter) && grid[4].equals(userCharacter) && grid[6].equals(userCharacter);
    }

    private boolean hasWonVertically(String userCharacter) {
        return grid[0].equals(userCharacter) && grid[3].equals(userCharacter) && grid[6].equals(userCharacter)
                || grid[1].equals(userCharacter) && grid[4].equals(userCharacter) && grid[7].equals(userCharacter)
                || grid[2].equals(userCharacter) && grid[5].equals(userCharacter) && grid[8].equals(userCharacter);
    }

    private boolean hasWonHorizontally(String userCharacter) {
        return grid[0].equals(userCharacter) && grid[1].equals(userCharacter) && grid[2].equals(userCharacter)
                || grid[3].equals(userCharacter) && grid[4].equals(userCharacter) && grid[5].equals(userCharacter)
                || grid[6].equals(userCharacter) && grid[7].equals(userCharacter) && grid[8].equals(userCharacter);
    }
}