ObjectOutputStream and ObjectInputStream can be used to write java.io.Serializable objects to a stream.
 
The use of ObjectOutputStream to save a gameboard to a file.

 
     try 
      {
         /* Scanning for saving file */

         File game = new File( "terras.game" );
         FileOutputStream ostream = new FileOutputStream( game );
         ObjectOutputStream p = new ObjectOutputStream(ostream);

          p.writeObject( getBoardPanel().getBoardSize() );

         // writing size of field
         for (int i=0; i < getBoardPanel().getBoardSize().width; i++)
         for (int j=0; j < getBoardPanel().getBoardSize().height; j++)
         {
            p.writeObject( getBoardPanel().getBoard()[i][j] );
         }

         p.flush();
         ostream.close();
         

      } catch (Exception e) {
         System.out.println( e.getMessage() );
         e.printStackTrace();
         System.exit(0);
      }



The use of ObjectInputStream to retrieve a saved gameboard.
      try 
      {
         /* Scanning for saving file */

         File game = new File( "terras.game" );
         if ( ! game.exists() )
         {
            throw new FileNotFoundException("cannot find previous 'terras.game' file");
         }

         
         FileInputStream istream = new FileInputStream( game );
         ObjectInputStream p = new ObjectInputStream(istream);

         Dimension sze = (Dimension) p.readObject(  );
         //getBoardPanel().getSize()
         Component [][] board = new Component[sze.width][sze.height];

         // writing size of field
         for (int i=0; i < sze.width; i++)
         for (int j=0; j < sze.height; j++)
         {
            board[i][j] = (Component) p.readObject();
         }

         getBoardPanel().setBoard( board );
         validate();

         istream.close();
         
      } catch (FileNotFoundException e) {
         System.out.println( e.getMessage() );
      } catch (Exception e) {
         System.out.println( e.getMessage() );
         e.printStackTrace();
         System.exit(0);  
      }