Difficulty with implementing a Swing Timer in java

Question

In this java game, I have an animation class that renders frames from a spritesheet. For the attack specifically, I made a different render method (renderAttack) because I want it to render all 16 frames of the animation, with 30 milliseconds in between each. I was looking into how to do delay the drawImage call, and decided a Swing Timer may be the best option. However, I am having the hardest time putting this in. Here is what I am trying to do, WITHOUT the timer:

public class Animation {

    public void renderAttack(Graphics g, int x, int y, int width, int height) {

        for(int index = 0; index < 16; index++)
        {
            g.drawImage(images[index], x, y, width, height, null);
            //wait 30ms
        } 
    }
}

To wait those 30 ms, I tried using the timer here. And as of now I have this:

public class Animation {

    public void renderAttack(Graphics g, int x, int y, int width, int height) {

        ActionListener taskPerformer = new ActionListener();
        Timer timer = new Timer(30, taskPerformer);
        timer.start();
    }
}

However, where would this go, and what is the ActionEvent that it takes in? And how can I pass in the index variable?

public void actionPerformed(ActionEvent e) {

    g.drawImage(images[index], x, y, width, height, null);
}

Hopefully this made any sense...I'll fix it step by step for now.

A complete example is examined [here](http://stackoverflow.com/a/3256941/2305130). — trashgod, Sep 14 '14 at 22:31
I think a better (general) solution would be to know what frame you are update AND what you should be animating. Then when the timer updates, you calculate what needs to be painted and update the state...You should also, reduce the number of `Timer`s or `Thread`s to as few as possible (like one of for example) — MadProgrammer, Sep 15 '14 at 00:00
I'm not updating any frame. Maybe I had a bad choice of words. "frame" can be replaces with "index" in the code. And when you ask what I should be animating: I'm drawing an image? Sorry, I'm a bit confused with what you are asking. — user3750325, Sep 15 '14 at 00:57

score 1 · Answer 1 · answered Sep 15 '14 at 01:29

Swing is a single threaded environment. You need to create your animation in a separate thread. I would suggest something like this:

public class Animation {
    Image[] images = null;

    public Animation() {
        // Define your images here and add to array;        
    }

    class AttackTask extends SwingWorker<Void, Void> {

        Graphics g = null;
        int x,y,width,height;

        AttackTask(Graphics g, int x, int y, int width, int height) {
            this.g = g;
            this.x = x;
            this.y = y;
            this.width = width;
            this.height = height;
        }

        @Override
        protected Void doInBackground() throws Exception {

            for(int frame = 0; frame < 16; frame++)
            {
                g.drawImage(images[frame], x, y, width, height, null);
                Thread.sleep(30);
            }

            return null;
        }

        @Override
        protected void done() {
            // Do something when thread is completed                    
        } 
    }
}

Difficulty with implementing a Swing Timer in java

1 Answers1