How to serialize an object that includes BufferedImages

Question

I\'m trying to create a simple image editing program in java. I made an ImageCanvas object that has all the information about the image that is being edited (so

Answer 1

Serialization is pretty straight-forward in that it persists static data. You are otherwise in the right place with read/write object in the Serialization family of methods. Think about what a "BufferedImage" is. It is a buffered streaming implementation. To serialize, the data must be flushed out to a static object like a byte[] array and then THAT object may be serialized/deserialized into/out of a BufferedImage such that the buffered streaming now comes in/out of that byte[] array.

Answer 2

make your ArrayList<BufferedImage> transient, and implement a custom writeObject() method. In this, write the regular data for your ImageCanvas, then manually write out the byte data for the images, using PNG format.

class ImageCanvas implements Serializable {
    transient List<BufferedImage> images;

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        out.writeInt(images.size()); // how many images are serialized?
        for (BufferedImage eachImage : images) {
            ImageIO.write(eachImage, "png", out); // png is lossless
        }
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        final int imageCount = in.readInt();
        images = new ArrayList<BufferedImage>(imageCount);
        for (int i=0; i<imageCount; i++) {
            images.add(ImageIO.read(in));
        }
    }
}