1. Set Up the Board!

In this activity, we will have a program that prints out the game board and gaming prompt, like the output below:

<<<~  Tic  Tac  Toe  ~>>>
* Choose number 1 - 9 to place your move
* Player: 'X' Computer: 'O'

 1 | 2 | 3 
---+---+---
 4 | 5 | 6 
---+---+---
 7 | 8 | 9 
Enter your move (1-9): 2
 O | X |   
---+---+---
   |   |   
---+---+---
   |   |   
Enter your move (1-9): 

The Main Class and Main Method

Notice that in the starter code, we have the class Main and the main() method. main() method is where the program starts whenever we click the Run button.

public class Main {
  public static void main(String[] args) {
  }
}

In main(), write print statement(s) to print the welcome statement and rules for the game!

<<<~  Tic  Tac  Toe  ~>>>
* Choose number 1 - 9 to place your move
* Player: 'X' Computer: 'O'

Variables and Arrays

In this game, we note that we will have to track the symbol currently in each of the 9 positions on the board.

Hence, we will need to store 9 pieces of data in the program. Let’s use an array(a data structure) of size 9 to store these information.

As stated in the rules, on the game board, "X" is the player’s move, "O" is a computer move, and " " is an available spot.

With these information, let’s declare an array variable called board with the values of 9 " " String (i.e {" ", " ", " ", " ", " ", " ", " ", " ", " "}).

Displaying the board

Now we have the variable board storing current symbols on the game board, let’s try to print out an empty game board using print statements (shown below).

Note that each game board consists of 5 lines, so it is reasonable to have 5 print statment to print out each board.

Each of the 9 blocks is a String of length 3, where the middle character is the current symbol stored in board at the corresponding position.

You should have a program that has the output below after completing this step.

<<<~  Tic  Tac  Toe  ~>>>
* Choose number 1 - 9 to place your move
* Player: 'X' Computer: 'O'

   |   |  
---+---+---
   |   |  
---+---+---
   |   | 

Methods

As we know we will need to print out the current game board several times throughout the game, so it will be a good idea to move the block of code you write in step 4 to a method.

This method should take an input of String[] and prints out the current board. Note that this method should be written outside of main().

Let’s write a method with the following header:

public static void printBoard(String[] curBoard);

Calling Methods

In main(), call the printBoard(), so it prints the initial board with labelled position. You can do this by creating another String array of the content "1", "2", ..., "9".

Have a line of code that prints Enter your move (1-9):

<<<~  Tic  Tac  Toe  ~>>>
* Choose number 1 - 9 to place your move
* Player: 'X' Computer: 'O'

 1 | 2 | 3 
---+---+---
 4 | 5 | 6 
---+---+---
 7 | 8 | 9 
Enter your move (1-9): 

Run the Program

Run your program, if it outputs the text above, you are ready to continue 👍!