Java - Crear barra de progreso en Java

public static List<XSLFSlide> crearPNG(String url) throws FileNotFoundException, IOException {

    FileInputStream is = new FileInputStream( url);

    XMLSlideShow pptx = new XMLSlideShow(is);

    List<File> images = new ArrayList<>();

    Dimension pgsize = pptx.getPageSize();

    List<XSLFSlide> slides = pptx.getSlides();

    for (int i = 0; i < slides.size(); i++) {

        BufferedImage img = new BufferedImage(pgsize.width, pgsize.height, 1);

        Graphics2D graphics = img.createGraphics();

        graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        graphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);

        graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);

        graphics.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);

        graphics.setColor(Color.white);

        graphics.clearRect(0, 0, pgsize.width, pgsize.height);

        graphics.fill(new Rectangle2D.Float(0, 0, pgsize.width, pgsize.height));

        XSLFSlide slide = slides.get(i);

        // render

        slide.draw(graphics);

        // save the output

        File pngFile = null;

        if (url.equals("tiempo.pptx")) {

            pngFile = new File("images/slide-mañana/", "slide-" + (i + 1) + ".png");

        } else {

            pngFile = new File("images/slide-tarde/", "slide-" + (i + 1) + ".png");

        }

        System.out.println((i + 1) + ") saving slide to " + pngFile.getName());

        FileOutputStream out = new FileOutputStream(pngFile);

        ImageIO.write(img, "png", out);

        out.close();

        images.add(pngFile);

    }

    pptx.close();

    return slides;

}

public static void crearVideoManana(String urltosave) throws IOException {

    AWTSequenceEncoder enc = AWTSequenceEncoder.create25Fps(new File(urltosave));

    int framesToEncode = 300;

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-1.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-2.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-3.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-4.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-5.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-6.png"));

        enc.encodeImage(img);

    }

    for (int i = framesToEncode / 2; i < framesToEncode; i++) {

        BufferedImage img = ImageIO.read(new File("images/slide-mañana/slide-7.png"));

        enc.encodeImage(img);

    }

    enc.finish();

}