Two-Dimensional Arrays

• When constructing a two-dimensional array, you specify how many rows and columns you need:

final int ROWS = 3;

final int COLUMNS = 3;

String[][] board = new String[ROWS][COLUMNS];

• You access elements with an index pair a[i][j]

board[i][j] = "x";

Traversing Two-Dimensional Arrays

It is common to use two nested loops when filling or searching:

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

   for (int j = 0; j < COLUMNS; j++)

      board[i][j] = " ";

Click here for TicTacToe program.

How do you declare and initialize a 4-by-4 array of integers?

   Answer:

  int[][] array = new int[4][4];
 

How do you count the number of spaces in the tic-tac-toe board?

   Answer:

  int count = 0;

  for (int i = 0; i < ROWS; i++)

     for (int j = 0; j < COLUMNS; j++)  

        if (board[i][j] == ' ') count++;