Data has been changed when save a BufferedImage to JPG, but work PNG

Question

I had a bufferedImage image with data {0; 24; 40; 0; 12; 28; 11; 37;....} and i saved it to a file with code:

File  file  = new File(filename);
BufferedImage image = ImageIO.read(file);
String ext = "jpg";

        try
        {
            file.delete(); 
            ImageIO.write(image,ext,file);
            return true;
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null,
                "Image could not be saved!","Error",JOptionPane.ERROR_MESSAGE);
            return false;
        }

but when i read it then, data has been changed. imgBytes = {2; 25; 41; 0; 13; 29; 12; 35; ...}

Can you help me make the data when write it as jpg, that data is not changed.

Thanks very much!

code read

 private void read()
    {
       img = ImageIO.read(file);
       BufferedImage image  = copyToBuffer(img);
       imgBytes = getImageBytes(image);
    }
    private BufferedImage copyToBuffer(BufferedImage image)
    {
        BufferedImage newImage  = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
        Graphics2D  graphics = newImage.createGraphics();
        graphics.drawRenderedImage(image, null);
        graphics.dispose();
        return newImage;
    }

    private byte[] getImageBytes(BufferedImage image)
    {
        WritableRaster raster   = image.getRaster();
        DataBufferByte buffer = (DataBufferByte)raster.getDataBuffer();
        return buffer.getData();
    }

Answer 1

Can you help me make the data when write it as jpg, that data is not changed.

Nope, impossible to use JPG. Even 100% quality JPG is lossy. You will have to go for PNG or something else non-lossy.