java: inner class, variable accessibility problem

nadroj · 10-05-2006, 08:46 PM

edit: sorry for the big indentations, looks fine maximized though

Code:

for (int y= 0; y < HEIGHT; y++)
		{
			for (int x = 0; x < WIDTH; x++)
			{
				hide[x][y] = '0';
				show[x][y] = new JButton(x +","+y);
				show[x][y].addMouseListener(new MouseAdapter()
				{
					public void mouseClicked(MouseEvent e)
					{
						check(x,y); //problem here
					}
				});
				show[x][y].setSize(500,100);
				frame.getContentPane().add(show[x][y]);	
			}						
		}

error message (in eclipse IDE): "Cannot refer to a non-final variable x inside an inner class defined in a different method"

as the error message states, making the x and y variables 'final' solves the problem, however, if they are final then they wouldnt be able to be incremented on each iteration of the for loop.

if i put this inner class in its own file and then applied it here then i wouldnt be able to access the x and y variables. i could overload the mouseClicked function with parameter list (MouseEvent e, int x, int y) but it wouldnt get called.

i havent tried it but maybe making the variables either global or static would solve it, but i dont want to have to resort to that.

any help appreciated thanks

crabboy · 10-05-2006, 09:01 PM

After this line try this:

show[x][y] = new JButton(x +","+y);

final int fx = x;
final int fy = y;

Use fx and fy in the inner class.

nadroj · 10-05-2006, 09:18 PM

it works, never thought of that. also not too much overhead because of the small scope it has.
thanks crabboy