title: Java Tic Tac Toe: convert string to check for value in 2d array
body: <p>I'm creating a simple tic tac toe game. I initialized my 3x3 board using a single space character.</p>
  
  <pre><code>private char[][] board;
  private char player; // 'X' or 'O'
  
  public TicTacToe() {
   for(int i = 0; i &lt; 3; i++)
     {
       for(int j = 0; j &lt;3; j++)
       {
         board[i][j] = ' ';
       }
     }
   player = 'X';
   }
  </code></pre>
  
  <p>I ask the user to enter the coordinates as shown below:</p>
  
  <pre><code>   1  2  3
  A |  |  |  |
  B |  |  |  |
  C |  |  |  |
  </code></pre>
  
  <p>so if X enters B2 and O enters A3, the board will look like this:</p>
  
  <pre><code>   1  2  3
  A |  |  |O |
  B |  | X|  |
  C |  |  |  |
  </code></pre>
  
  <p>Right now, I'm trying to code a method that checks to see if a current player's move is valid.</p>
  
  <p>Question:
    <strong>How do I convert the user string input (A=1,B=2,C=3) so that I can see if board[x][y] contains a ' ' character?</strong></p>