Listener event

Question

I am trying to create a small game got most of the functionality, apart from one aspect how would you code an Listener event that would take into account that if any two pawns on a chessboard were on the same line in any direction then that row would become highlighted and the user could not place any more pawns on that row?
I know a wee bit about �if� and �else� statements but I have no idea how you would create code that would carry out the above function.
Any help would be great
Tom
// <applet code="ChessBored.class" width="500" height="500"></applet>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class ChessBored  extends JApplet
  public void init()
     JFrame f = new JFrame("Chess Board");
     ChessBoard board = new ChessBoard();
     f.getContentPane().add(board);
     f.setSize(board.WIDTH, board.HEIGHT);
     f.setVisible(true);
   } // end init
  public class ChessBoard extends JPanel implements MouseListener
    private Color[] squareColor = new Color[2];
    private final int NUMSQUARES = 8, WIDTH = 400, HEIGHT = 400;
    private int squareSize;
    private int boardSize;
/* The constructor sets only some of the instance variables.
   The rest are set when the screen is painted.
   public ChessBoard()
      squareColor[0] = Color.black;
      squareColor[1] = Color.white;
      addMouseListener(this);
      setSize(WIDTH, HEIGHT);
/* The paintComponent method is called every time the display
   needs to be repainted. Examples: When the window is
   first displayed, when the window is moved, resized,
   maximized, etc.
   Draws an 8x8 grid of alternately colored squares.
   Make the grid as large as it can be to fit in the
   current size of the drawing pane (which is the content pane
   for the JFrame).
    public void paintComponent (Graphics g)
      super.paintComponent(g);  // Make sure background is cleared
      int paneHeight = this.getHeight();
      int paneWidth  = this.getWidth();
      if (paneHeight < paneWidth)
        squareSize = paneHeight / NUMSQUARES;
      else
        squareSize = paneWidth / NUMSQUARES;
      boardSize = squareSize * NUMSQUARES;
      for (int row=0; row<NUMSQUARES; row++)
         for (int col=0; col!=NUMSQUARES; col++)
        { g.setColor(squareColor[(row+col)%2]);
          g.fillRect(col*squareSize,   // x
                     row*squareSize,   // y
                     squareSize,       // width
                     squareSize);      // height
    } // end paintComponent
/** The mouseClicked method responds to any mouse clicks.
    public void mousePressed(MouseEvent e)
// Quit if the mouse press falls outside the board
      Point p = e.getPoint();
      int x = (int) p.getX();
      int y = (int) p.getY();
      if((x>boardSize) || (y>boardSize))
        return;
// Determine which square (i.e. row, col) was selected
      int row = y / squareSize;
      int col = x / squareSize;
      if (row <= 8)
        drawPawn(row, col, Color.blue);
    //else
      //if (row >= (NUMSQUARES-2))
        //drawPawn(row, col, Color.black);
      //else
       // drawMessage(row, "Checkmate!");
/* These four methods are not used, but must be
   implemented because they are required by the
   MouseListener interface.
    public void mouseEntered(MouseEvent e)  {}
    public void mouseExited(MouseEvent e)   {}
    public void mouseClicked(MouseEvent e)  {}
    public void mouseReleased(MouseEvent e) {}
/** The drawPawn method draws a pawn shape on the
    specified square in the chess board.
    public void drawPawn(int row, int col, Color c)
      Graphics g = this.getGraphics();
      g.setColor(c);
// Calculate position of upper left corner of square
      int x = col*squareSize;
      int y = row*squareSize;
/* Draw circle for "head" of the pawn. Dimensions are
   for the oval's "bounding box".
      g.fillOval(x+(2*squareSize/5), // x
                 y+(squareSize/5),   // y
                 squareSize/5,       // width
                 squareSize/5);      // height
// Draw a polygon for the "body" of the pawn.
      Polygon body = new Polygon();
      body.addPoint(x+(2*squareSize/5),
                    y+(2*squareSize/5));
      body.addPoint(x+(3*squareSize/5),
                    y+(2*squareSize/5));
      body.addPoint(x+(4*squareSize/5),
                    y+(4*squareSize/5));
      body.addPoint(x+(squareSize/5),
                    y+(4*squareSize/5));
      g.fillPolygon(body);
    } // drawPawn
/** The drawMessage method draws the given string in
    the given row of the chess board, centered
    horizontally.
    public void drawMessage(int row, String s)
//Set a new font and color
      Font bigFont = new Font("Times New Roman", Font.BOLD, 36);
      Graphics g = this.getGraphics();
      g.setFont(bigFont);
      g.setColor(new Color(0.8F, 0.8F, 1.0F));
//Determine the position of the string
      FontMetrics m = g.getFontMetrics();
      int x = (boardSize - m.stringWidth(s)) / 2;
      if (x < 0)
        x = 0;
      int y = ((row+1)*squareSize) - m.getDescent();
      if (y<0)
        y = m.getLeading() + m.getAscent();
      g.drawString(s, x, y);
    } // drawMessage
  } // end ChessBoard
} // end ChessBored

Answer 1

One thing that sticks out is your listener method isn't quite to spec, according to the f:ajax spec they're supposed to match the following signature:
javax.el.MethodExpression
(signature must match public void processAjaxBehavior(javax.faces.event.AjaxBehaviorEvent event) throws javax.faces.event.AbortProcessingException)
Try dropping the boolean return value & adding the throws. I'm running Apache's MyFaces and it's perfectly fine with your method signature, but maybe your JSF implementation isn't.
Also, you running with javax.faces.PROJECT_STAGE set to Development? Maybe some useful server-side error you're not seeing. You probably should also create your own ExceptionHandler to dump stack traces to the console/logs if you haven't done so already as well.
And lastly, you sure all your code's published to the server? If you're still stuck, then the best thing to do is to make this page as simple as possible, put just 1 checkbox w/o all the table/repeats/etc. to help you eliminate other possibilities.
Sorry can't be more helpful...