With the release of office-stamper v3.0, much of the spotlight has been on the new hierarchical context and the engine refactoring. However, one of the most significant changes for the long-term health of the project happened in the “shadows”: the creation of the utils module.

This month, I completed the migration of our document traversal logic into a dedicated, standalone module. It’s more than just a package move; it’s a commitment to building a “library within a library.”

The Thesis: Decoupling the “Dirty Work”

Interacting with docx4j and the underlying Open XML structures is notoriously complex. In v2.x, this “dirty work”—traversing paragraphs, handling nested tables, unwrapping JAXB elements—was tightly coupled with the stamping logic.

For v3, I wanted to isolate this complexity. The goal for the utils module is twofold:

  1. Clarity: The core engine should only care about what to do with a placeholder, not how to find the next one in a PPTX slide vs. a Word header.
  2. Reusability: I want these utilities to be visible and independent. If I (or you) need a robust way to iterate through a PowerPoint presentation in another project, these tools should be ready to use without dragging in the entire template engine.

The Technique: Format-Agnostic Iterators

The heart of the utils module is the ResetableIterator interface. It provides a unified way to walk through different Office formats while allowing the engine to “reset” the state when a mutation occurs (a technique I detailed earlier this month).

We now have high-fidelity implementations for the three major formats:

  • DocxIterator: The most mature implementation, handling paragraphs, tables, and nested content.
  • PptxIterator: Navigates slides, shapes, and text blocks.
  • XlsxIterator: Traverses sheets, rows, and cells.
/// XlsxIterator is an [ResetableIterator] implementation that iterates through 
/// the elements of an Excel spreadsheet document.
///
/// The iterator automatically traverses the hierarchical structure of the 
/// spreadsheet, unwrapping nested elements and providing a flat iteration 
/// interface over all contained objects.
public class XlsxIterator implements ResetableIterator<Object> {
    // ... logic to unwrap Sheet, Row, and ContentAccessor elements ...
}

Worked Example: OpenpackagingFactory

To further reduce boilerplate and improve safety, I’ve introduced factories that wrap docx4j’s checked exceptions into runtime UtilsException. This makes the code much cleaner when working with PartName or WordprocessingMLPackage.

// Modern v3 utility usage
PartName name = OpenpackagingFactory.newPartName("/word/document.xml");

Sharp Edges: The Maturity Gradient

While DocxIterator is battle-tested by the core engine, PptxIterator and XlsxIterator are still in their early stages. They were primarily updated this month to follow the deprecation of the interfaces they previously extended. They provide the structural foundation for v3, but they haven’t yet reached the same level of stamping maturity as the Word implementation.

As a solo maintainer, I’ve learned that it is better to have a solid, well-documented foundation for these formats now, even if the high-level features are still evolving.

Impact: A Niche for the World

By moving these utilities to a dedicated module and documenting them with the new Java 25 Markdown Javadoc (the /// syntax you’ll see in the patch), I’m signaling that these are first-class citizens.

  • For Users: You get a more stable and predictable engine.
  • For Me: I have a reusable toolbelt for my other document-processing projects.
  • For the World: If you have a niche need for flat iteration over complex XML documents, the utils module is here for you.

December 22nd 2025 — Commit Summary:

  • Major: Created standalone utils module to decouple document traversal.
  • Feat: Migrated and refined DocxIterator, PptxIterator, and XlsxIterator.
  • Feat: Introduced OpenpackagingFactory to simplify docx4j object creation.
  • Docs: Added comprehensive Markdown Javadoc to all utility classes.
  • Refactor: Standardized exception handling with the new UtilsException.