Tic Tac Toe

// Tic Tac Toe program that plays the game with user
// Renee Waggoner
// July 26, 2019
// Special Requirements: None
package tic_tac_toe;
import java.util.*;
class TicTacToe
{
    char ttt[][] = new char[3][3];
    static final char player1 = 'O';
    static final char player2 = 'X';
    Scanner scan =new Scanner(System.in);

    String playerID(char player)
    {
        // Prints the identity of the player
        // For example:
        // player2: X
        if (player == player1)
            return "player1: " + player;
        else
            return "player2: " + player;
    }

    void getPlayerInput(char player)
    {
        // ******* Details to fill in ************

        // Prompt the user for a cell input. Make sure its a legal
        // cell designator. Also make sure the cell doesn't already
        // have a player in it. Prompt the user again in the case
        // of any problem. Once a valid spot has been found,
        // you will issue a statement like:
        char choice;
        System.out.println("Entering Input For:" + playerID(player));

        System.out.println("enter in cell [a, b, ... i]");
        choice = scan.next().charAt(0);

        switch(choice)
        {
        case 'a':ttt[0][0] = player;break;
        case 'b':ttt[0][1] = player;break;
        case 'c':ttt[0][2] = player;break;
        case 'd':ttt[1][0] = player;break;
        case 'e':ttt[1][1] = player;break;
        case 'f':ttt[1][2] = player;break;
        case 'g':ttt[2][0] = player;break;
        case 'h':ttt[2][1] = player;break;
        case 'i':ttt[2][2] = player;break;
        }

    }

    boolean gameIsDraw()
    {
        // ******* Details to fill in ************
        // If all ttt entries have been taken return true
        // otherwise return false
        for(int i = 0; i < ttt.length; i++)
            for(int j = 0; j < ttt [i].length; j++)
                if( ttt [i][j] == ' ')
                    return false;
        return true;
    }

    boolean winner(char player)
    {
        // ******* Details to fill in ************
        // Check to see if the parameter player has won
        // Winning means that player shows up in a line of
        // three. The line can be a column, row or a diagonal
        // Return true if player is a winner, otherwise return false.
        for(int i = 0; i < 3; i++)

            if(ttt[i][0] == player && ttt[i][1] == player && ttt[i][2] == player)
                return true;

        for(int i = 0; i < 3; i++)

            if(ttt[0][i] == player && ttt[1][i] == player && ttt[2][i] == player)
                return true;

        if(ttt[0][0] == player && ttt[1][1] == player && ttt[2][2] == player)
            return true;

        if(ttt[2][0] == player && ttt[1][1] == player && ttt[0][2] == player)
            return true;

        return false;

    }

    void displayBoard()
    {
         // ******* Details to fill in ************
        // game board spacing
            System.out.println("===============================e");
            System.out.println("--a-----b-----c--");
            System.out.println("| "+ttt[0][0]+"   | "+ttt[0][1]+"   | "+ttt[0][2]+" |\n");
            System.out.println("--d-----e-----f--");
            System.out.println("| "+ttt[1][0]+"   | "+ttt[1][1]+"   | "+ttt[1][2]+" |\n");
            System.out.println("--g-----h-----i--");
            System.out.println("| "+ttt[2][0]+"   | "+ttt[2][1]+"   | "+ttt[2][2]+" |\n");
            System.out.println("-----------------");

        }

    void newgame()
    {
        char currPlayer = player1;
        for(int i = 0; i < 3; i++)
            for(int j = 0; j < 3; j++)
                ttt [i][j] =' ';
        boolean continueOn = true;
        while (continueOn)
        {
            displayBoard();
            if (gameIsDraw())
            {
                System.out.println("******** Game Ends in Draw");
                continueOn = false;
            }
            else
            {
                getPlayerInput(currPlayer);
                if (winner(currPlayer))
                {
                    System.out.println("******** We have a winner: " + playerID(currPlayer));
                    // calling displayBoard method
                    displayBoard();
                    continueOn = false;
                }
                else
                {
                    if (currPlayer == player1) currPlayer = player2;
                    else currPlayer = player1;
                }
            }
        }
    }
    public static void main(String[] args)
    {
        TicTacToe game = new TicTacToe();
        String str;
        do
        {
            game.newgame();
            System.out.println("Do you want to play Tic-Tac-Toe (y/n)?");
            str = game.scan.next();
        } while ("y".equals(str));
        // otherwise prints Bye
        System.out.println("Bye");
    }
}