Written Book Serialization (Destructive 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(0) == null) || (pages.tagAt(0).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(0).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(0).toString());
        // This is a DEstructive version, so remove the first page (calls ".remove(0)" on
        // the list holding NBT tag internally)
        pages.removeTag(0);
    }
    // End of serialization, print a message, return the result
    err.println("Serialization complete");
    return data.toString();
}