Drawing a map

[Karp]

Hi

I'm making an application, a little game, and I need to draw the map on the screen. The map is just a 2D array and I want to draw it using lines and such. I've managed to draw something on the screen but I need to pass the map to the drawing class and that I don't know how to do.

Here are some of the main parts of the code (stripped and modified, but the important parts are there).

The main program:

public class Game extends JFrame{

    public static void main(String[] args){

        Game game = new Game();

        Map map = new Map(20, 8);

        game.setSize(800, 600);
        DrawScreen ds = new DrawScreen();
        game.getContentPane().add(ds);
        game.setVisible(true);
    }

    public Game(){
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

A test drawer:

public class DrawScreen extends JPanel{
    public void paintComponent( Graphics g ){
        g.setColor( Color.RED );
        g.drawOval(0, 0, 100, 50);
    }
}

Now, this works just fine: it draws the oval. If I want to draw the map, I'd need to give the map to paintComponent as a parameter but I'm clueless about how to do it. I've looked around the net but haven't found a similar scenario. I understand it's possible to somehow add objects to the frame or something but that seemed unnecessarily complex for me, I just need a couple of for loops to draw the primitives. If you know the solution or an easier way, let me know. Thanks.

[Norm]

I need to pass the map to the drawing class

You could pass the map in DrawScreen constructor:
= new DrawScreen(map);

[Karp]

Thanks for the answer.

That works, though it seems like a bit of a waste to store the map data in DrawScreen as well, but that's not a big issue.

[DarrylBurke]

Thanks for the answer.

That works, though it seems like a bit of a waste to store the map data in DrawScreen as well, but that's not a big issue.

Unless you clone the map, you're not duplicating any data anywhere, just creating another variable that references the same map.

Brush up on the difference between objects and references.

db

[Karp]

Ah yes, of course.

I'm a bit rusty, it's been a few years since my last Java course.