One level of indentation per method

board-before.java

class Board 
{
  ...

  String board() 
  {
    StringBuffer buf = new StringBuffer();
    for (int i = 0; i < 10; i++) 
    {
      for (int j = 0; j < 10; j++) 
      {
        buf.append(data[i][j]);
      }
      buf.append("\n");
    } 
    return buf.toString();
  }
}