Java - Cannot view modified metadata

Question

I have been trying to access modified metadata of images in Java for the past few hours. I know I am one or two steps away from getting the correct output. Would really appreciate if someone can help me with this.

I want to add an extra field in the metadata, which is like an text similar to: Writing image metadata in Java, preferably PNG

My issue is that when i add the custom data to my image and when i read the image, i do not see the change in the modified metadata when i call the method readAndDisplay. I think the reason is that i am not saving the image properly into a new file with the modified metadata. Can someone have a look at what i am missing from my code:

public class Metadata {

public static void main(String[] args) throws Exception {
     String imageFile = "134.png";
     BufferedImage img = null;

     try {
            img = ImageIO.read(new File(imageFile));
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
    Metadata meta = new Metadata();
    byte[] result = meta.writeCustomData(img, "decimalID", "211");
    BufferedImage output = ImageIO.read(new ByteArrayInputStream(result));
ImageIO.write(output, "png", new File("output.png"));
meta.readAndDisplayMetadata("output.png");
}

void readAndDisplayMetadata( String fileName ) {
    try {

        File file = new File( fileName );
        ImageInputStream iis = ImageIO.createImageInputStream(file);
        Iterator<ImageReader> readers = ImageIO.getImageReaders(iis);
        if (readers.hasNext()) {

            // pick the first available ImageReader
            ImageReader reader = readers.next();

            // attach source to the reader
            reader.setInput(iis, true);

            // read metadata of first image
            IIOMetadata metadata = reader.getImageMetadata(0);

            String[] names = metadata.getMetadataFormatNames();
            int length = names.length;
            System.out.println(length);
            for (int i = 0; i < length; i++) {
                System.out.println( "Format name: " + names[ i ] );
                displayMetadata(metadata.getAsTree(names[i]));
            }
        }
    }
    catch (Exception e) {

        e.printStackTrace();
    }
}

void readAndDisplayMetadata( byte[] image ) {
    try {

       // File file = new File( fileName );

        ImageInputStream iis = ImageIO.createImageInputStream(new ByteArrayInputStream(image));
        Iterator<ImageReader> readers = ImageIO.getImageReaders(iis);
        if (readers.hasNext()) {

            // pick the first available ImageReader
            ImageReader reader = readers.next();

            // attach source to the reader
            reader.setInput(iis, true);

            // read metadata of first image
            IIOMetadata metadata = reader.getImageMetadata(0);

            String[] names = metadata.getMetadataFormatNames();
            int length = names.length;
            System.out.println(length);
            for (int i = 0; i < length; i++) {
                System.out.println( "Format name: " + names[ i ] );
                displayMetadata(metadata.getAsTree(names[i]));
            }
        }
    }
    catch (Exception e) {

        e.printStackTrace();
    }
}


void displayMetadata(Node root) {
    displayMetadata(root, 0);
}

void indent(int level) {
    for (int i = 0; i < level; i++)
        System.out.print("    ");
}

void displayMetadata(Node node, int level) {
    // print open tag of element
    indent(level);
    //System.out.println("Attributes: " + node.getAttributes().getLength());
    System.out.print("<" + node.getNodeName());
    NamedNodeMap map = node.getAttributes();
    if (map != null) {

        // print attribute values
        int length = map.getLength();

        for (int i = 0; i < length; i++) {
            Node attr = map.item(i);
            System.out.print(" " + attr.getNodeName() +
                             "=\"" + attr.getNodeValue() + "\"");
        }
    }

    Node child = node.getFirstChild();
    if (child == null) {
        // no children, so close element and return
        System.out.println("/>");
        return;
    }

    // children, so close current tag
    System.out.println(">");
    while (child != null) {
        // print children recursively
        displayMetadata(child, level + 1);
        child = child.getNextSibling();
    }

    // print close tag of element
    indent(level);
    System.out.println("</" + node.getNodeName() + ">");
}

public byte[] writeCustomData(BufferedImage buffImg, String key, String value) throws Exception {
    ImageWriter writer = ImageIO.getImageWritersByFormatName("png").next();

    ImageWriteParam writeParam = writer.getDefaultWriteParam();
    ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);

    //adding metadata
    IIOMetadata metadata = writer.getDefaultImageMetadata(typeSpecifier, writeParam);

    IIOMetadataNode textEntry = new IIOMetadataNode("tEXtEntry");
    textEntry.setAttribute("keyword", key);
    textEntry.setAttribute("value", value);

    IIOMetadataNode text = new IIOMetadataNode("tEXt");
    text.appendChild(textEntry);

    IIOMetadataNode root = new IIOMetadataNode("javax_imageio_png_1.0");
    root.appendChild(text);

    metadata.mergeTree("javax_imageio_png_1.0", root);


    //writing the data
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageOutputStream stream = ImageIO.createImageOutputStream(baos);
    writer.setOutput(stream);

    writer.write(metadata, new IIOImage(buffImg, null, metadata), writeParam);

    stream.close();

    return baos.toByteArray();
}