Flickering images in java, BufferStrategy?

Question

I'm making a game in java and need to paint units on a gameboard. I put all units in a list and paints every unit in that list. The paint method looks like this:

  public void paint(Graphics g) {
        super.paint(g);

        if (unitList != null) {
            Collections.sort(unitList);
            for (Unit unit : unitList) {
                Image image = unit.getImage();
                g.drawImage(
                        image,
                        (int) (playPosition.x + unit.getPosition().getX() - image
                                .getWidth(null) / 2), (int) (playPosition.y
                                + unit.getPosition().getY() - image
                                .getHeight(null) / 2), null);
            }
        }
    }

I have tried to make a BufferStrategy but it only makes the problem worse, guess I am doing something wrong.

Thanks

Answer 1

Maybe you haven't implemented BufferStrategy correctly.
Try manual double buffering by doing offscreen painting on an Image, and then just paint the whole said image in your regular overriden paint() method.

You would do that like so:

// Double buffering objects.
Image doubleBufferImage;
Graphics doubleBufferGraphics;

/*
 * Onscreen rendering.
 */
 @Override
 public void paint(Graphics g) {
     doubleBufferImage = createImage(getWidth(), getHeight());
     doubleBufferGraphics = doubleBufferImage.getGraphics();
     paintStuff(doubleBufferGraphics);
     g.drawImage(doubleBufferImage, 0, 0, this);
 }

/*
 * Offscreen rendering.
 */
 public void paintStuff(Graphics g) {
     if (unitList != null) {
        Collections.sort(unitList);
        for (Unit unit : unitList) {
            Image image = unit.getImage();
            g.drawImage(
                    image,
                    (int) (playPosition.x + unit.getPosition().getX() - image
                            .getWidth(null) / 2), (int) (playPosition.y
                            + unit.getPosition().getY() - image
                            .getHeight(null) / 2), null);
        }
    }
 }