Java – use imageio Write() creates a JPEG file of 0 bytes

I'm trying to write a way to take an image and save a 100 x 100 thumbnail of the image However, when I save the file, it is an unreadable 0-byte image (error interpretation "error interpretation JPEG image file (error call to JPEG Library in state 200)") in Ubuntu's ImageViewer My code is as follows:

public boolean scale(){

    String file = filename.substring(filename.lastIndexOf(File.separator)+1);
    File out = new File("data"+File.separator+"thumbnails"+File.separator+file);

    if( out.exists() ) return false;

    BufferedImage bi;
    try{
        bi = ImageIO.read(new File(filename));
    }
    catch(IOException e){
        return false;
    }

    Dimension imgSize = new Dimension(bi.getWidth(),bi.getHeight());
    Dimension bounds = new Dimension(100,100);
    int newHeight = imgSize.height;
    int newWidth = imgSize.width;

    if( imgSize.width > bounds.width ){
        newWidth = bounds.width;
        newHeight = (newWidth*imgSize.height)/imgSize.width;
    }

    if( imgSize.height > bounds.width ){
        newHeight = bounds.height;
        newWidth = (newHeight*imgSize.width)/imgSize.height;
    }

    Image img = bi.getScaledInstance(newWidth,newHeight,BufferedImage.SCALE_SMOOTH);
    BufferedImage thumb = new BufferedImage(newWidth,BufferedImage.TYPE_4BYTE_ABGR);
    Graphics2D g2d = thumb.createGraphics();
    g2d.drawImage(img,null);
    g2d.dispose();

    try{
        ImageIO.write(thumb,"jpg",out);
    }
    catch(IOException e){
        return false;
    }

    return true;
}

Where "filename" is the global variable of the class containing this method, representing the path of the original image My main problem is that I don't understand why I want to create a 0 - byte image

Solution

So the problem is this I work in openjdk Obviously, openjdk does not have a JPEG encoder, so when creating files

ImageIO.write(thumb,out);

It doesn't actually create anything for the file to be saved; Therefore, an empty 0 byte unreadable file Changing the imageio parameter to "PNG" (and adjusting the new file () extension accordingly) has successfully created the required image using the above code