Written Book Serialization (Nondestructive Copy Version)

public static final String serialize(ItemStack book) {
        // Require that we get a written book for serialization
        if (book.itemID != Item.writtenBook.itemID) {
                throw new IllegalArgumentException("WrittenBookTag.serialize(ItemStack) must be passed an ItemStack holding a written book");
        }
        NBTTagCompound tag = book.getTagCompound();
        // Play it safe
        if (tag == null) {
                tag = new NBTTagCompound();
        }
        // This is where the serialized content will go
        StringBuffer data = new StringBuffer();
        // Start with the title, then the author
        // 'sep' is a String holding the system line separator
        data.append(tag.getString("title") + sep + tag.getString("author") + sep);
        // Make a copy of the tags, so we don't mess around with the actual book
        NBTTagList pages = (NBTTagList) tag.getTagList("pages").copy();
        // Find out how many times we should loop
        int tagCount = pages.tagCount();
        // Debug line, print the number of pages
        err.println("Beginning serialization of " + tagCount + " pages");
        // Start serialization
        for (int i = 0; i < tagCount; i++ ) {
                // Catch exceptions
                try {
                        // More debug
                        err.println("Getting page " + i);
                        // Don't operate on a null page, that'll just break things
                        if ((pages.tagAt(i) == null) || (pages.tagAt(i).toString() == null)) {
                                err.println("Null page found, terminating loop");
                                break;
                        }
                        // Debug again; current page index (zero-based) and the content
                        // This always gives the correct index and the content of the FIRST page,
                        // every time! The loop counter increments correctly, but I can't get any
                        // page after the first one.
                        err.println("Current page (" + i + "): " + pages.tagAt(i).toString());
                }
                // NBTTagList directly uses a List (untyped), and does no bounds checking,
                // so catch Index OOB here, just in case. Never actually happened to me,
                // but better safe than sorry.
                catch (IndexOutOfBoundsException e) {
                        err.println("Index " + i + " OOB, terminating");
                        break;
                }
                // Same deal, if we get a null pointer, don't explode.
                catch (NullPointerException e) {
                        err.println("NPE on index " + i + ", terminating");
                        break;
                }
                // Another bit of debug...
                err.println("Appending page to serialized string");
                // The string "--PAGEBREAK--" is used to indicate that a new page should be started.
                // It makes the serialized form a bit more human-readable.
                data.append((i > 0 ? sep + "--PAGEBREAK--" + sep : "") + pages.tagAt(i).toString());
        }
        // End of serialization, print a message, return the result
        err.println("Serialization complete");
        return data.toString();
}