Thread: Tic-Tac-Toe (loops, arrays, and methods) help please

So I am having trouble with a few of things. We have to create an empty array filled with '-' characters to start. I have finished the parts where it randomly pics player1 or player2 to start and displaying an empty board. There are 3 things I am having problems with (will post code below with sample output). 1, I am having trouble getting the input from the user and replacing the '-' with an x or an o. next, after the player pics it will show the board and ask the other player to pic. The last method scans it to see if there is a winner, i know how to get it to scan the rows and columns but not diagonal. Any help would be useful, thanks Smile
oh and i left the methods i need help with empty with descriptions above them. it got kind of messy trying out different things.

Code:

package lab07;
import java.util.Scanner;
import java.util.Random;
/**
*
* @author
*/
public class Lab07 {

/**
* @param args the command line arguments
* Do not change main()
*/
public static void main(String[] args) {
char [] [] board; char win; char player;
int size = getBoardSize();

while(size >= 3) {
board = createEmptyBoard( size );
player = getStartingPlayer();
do {
getMove(board, player);
player = player=='O'?'X':'O'; // switch players
win = checkForWin(board);
} while(win == 'N'); // must be F, O or X to leave loop
if(win == 'F'){
System.out.printf("\nThe board is Full: no Winner\n");
} else {
System.out.printf("\nThe winner is %c\n", win);
}
displayBoard(board);
size = getBoardSize();
} // end play games loop
} // end main

/*
* returns 3, 4 or 5 for the size of the play board
* or -1 to quit
* This is complete, no changes necessary
*/
public static int getBoardSize() {
int retval;
Scanner keyboard = new Scanner(System.in);
do {
System.out.printf("Enter board size 3, 4, 5 or -1 to quit: ");
retval = keyboard.nextInt();
} while(retval != 3 && retval != 4 && retval != 5 && retval != -1);

keyboard.nextLine(); // you should know why by now

return retval; // this MUST BE LAST LINE in this method()
} // getBoardSize

/*
* randomly selects X or O as the starting player
*
*/
public static char getStartingPlayer(){
char retval = 'X';

Random randomNumbers = new Random();
int player = randomNumbers.nextInt(2);

switch (player) {
case 0:
retval = 'O';
break;

case 1:
retval = 'X';
break;
}//end switch


System.out.printf("\n\tNew Game. Starting player is %c\n", retval);
return retval; // this MUST BE LAST LINE in this method()
} // end getStartingPlayer

/**
* gets new memory for a board and fills all cells with a minus sign '-'
* @param size the board if 3 is 3 x 3, if 4 is 4 x 4 etc.
*/
public static char [][] createEmptyBoard(int size) {
char [] [] board = new char [size][size];

for (char row = 0; row < board.length; row++) {
System.out.println();
for (char col = 0; col < board[row].length; col++) {
board[row][col] = '-';
System.out.print(board[row][col] + "\t");

}//end col
}//end row

return board; // this MUST BE LAST LINE in this method()
} // end createEmptyBoard

/**
* 1. displays board and
* 2. gets row column indexes for next move
* 3. makes sure the cell has a '-' is a legal move
* 4. loops till legal
* 5. puts the player's X or O at that cell
* @param board the current play board
* @param the X or O of the current player
*/
public static void getMove(char [][] board, char player){
System.out.printf("Player %c move\n", player);
displayBoard(board);




} // end getMove

/*
* displays the current play board to the console
* @param board the current play board to be displayed
*/
public static void displayBoard(char [][] board) {

} // end displayBoard

/* returns X, O, F or N
* returns X for X wins
* O for O wins
* F for board Full no winner
* or N for No winner yet
* @param board, the current play board to be checked
*/
public static char checkForWin(char [][] board){
char retval = 'F'; //


return retval; // this MUST BE LAST LINE in this method()
} // end checkForWin


}


Sample Output:

Enter board size 3, 4, 5 or -1 to quit: 3

New Game. Starting player is X

Player X move
- - -
- - -
- - -
Enter Row: >=0 and <= 2 1
Enter Col: >=0 and <= 2 1
Player O move
- - -
- X -
- - -
Enter Row: >=0 and <= 2 2
Enter Col: >=0 and <= 2 2
Player X move
- - -
- X -
- - O
Enter Row: >=0 and <= 2 1
Enter Col: >=0 and <= 2 0
Player O move
- - -
X X -
- - O
Enter Row: >=0 and <= 2 0
Enter Col: >=0 and <= 2 0
Player X move
O - -
X X -
- - O
Enter Row: >=0 and <= 2 1
Enter Col: >=0 and <= 2 2

The winner is X
O - -
X X X
- - O
Enter board size 3, 4, 5 or -1 to quit: -1

[code]-tags?

Which is the user? Is the user always 'X' or is the user always 'O' or what?

I mean, your getMove() method must know whether it is supposed to get a move from the user or get a move from the computer.

If it is getting from the user, then there would be a loop that prompts the user and reads row and column number and sees whether they correspond to a valid move. The loop repeats until it sees a valid move (move to a place presently occupied by '-').

If it is getting from the computer, then one way would be to get two random numbers and see whether they correspond to a valid move. The loop repeats until it sees a valid move (move to a place presently occupied by '-').

On the other hand...

I would probably have two methods: One for user move and one for computer move. Then the main() loop would decide which to call for a given move. Or some such thing.


Cheers!

Z