# Repository Overview

Welcome! This repository contains a small collection of Java classes that explore different source-file header styles. If you've just landed here, you're looking at a compact demo codebase — no large framework to untangle, no monolith to navigate. Let's get straight to what's here.

## Overview

This repository is a lightweight Java project consisting of a handful of single-class source files, each illustrating a distinct pattern for placing headers at the top of a Java source file. It appears to be a test or demonstration codebase rather than a production application, serving as a reference for how headers — version control metadata, license blocks, module documentation — can be structured across a Java codebase. Whether you're curious about header conventions, studying how version history can be embedded in source files, or just exploring the repository, you'll find all the code in a flat `src/main/java/` directory.

## Technology Stack

- **Java** — primary language (all sources are `.java` files)
- **No external frameworks or libraries detected** — the classes are self-contained with no imports beyond the Java standard library.

## Architecture

The repository has a single flat directory structure with no sub-modules, packages, or layered architecture. Each Java file is an independent, public class with no dependencies on the others. Below is a high-level view of the file layout.

```mermaid
flowchart TD
    A["src/main/java"] --> B["WithHeader"]
    A --> C["NoHeader"]
    A --> D["PartialHeader"]
    A --> E["LongHeader"]
    A --> F["Crosslink"]
    A --> G["MitLicense"]

    B["WithHeader"] --> H["Standard header format"]
    C["NoHeader"] --> I["No header at all"]
    D["PartialHeader"] --> J["Partial header block"]
    E["LongHeader"] --> K["Extended version history"]
    F["Crosslink"] --> L["Crosslink with versioned sections"]
    G["MitLicense"] --> M["MIT License header"]

    style A fill:#e1f5fe
    style H fill:#f3e5f5
    style I fill:#f3e5f5
    style J fill:#f3e5f5
    style K fill:#f3e5f5
    style L fill:#f3e5f5
    style M fill:#f3e5f5
```

## Module Guide

There is one top-level module: **root** (`src/main/java/`).

The root module contains six Java source files, each representing a standalone public class. None of the classes depend on each other, and none define any methods beyond what the Java language implicitly provides (e.g., a default constructor). The distinguishing feature of each class is its header — the block comment (or lack thereof) at the top of the file.

- **WithHeader.java** — Demonstrates a standard Javadoc-style header containing a processing name and version identifier. This is the most conventional approach to a Java file header.
- **NoHeader.java** — The simplest possible file: no comment block at all, just a bare `public class` declaration. It serves as the baseline or control case.
- **PartialHeader.java** — Contains a Javadoc block with module name and function summary fields (in Japanese), but without a version history line. It appears to document a class responsible for dispatching service orders during reference checks and cross-file modifications.
- **LongHeader.java** — The most distinctive file in the repository. Its Javadoc header spans over 250 lines, each recording a version bump with a ticket number and author. It showcases how extensive version history can be embedded directly in source files, though this pattern is uncommon in practice.
- **Crosslink.java** — Includes a standard header with a processing name, plus versioned inline code sections marked with `ADD START` / `ADD END` comments. This suggests a pattern for tracking incremental additions to the class body.
- **MitLicense.java** — A minimal file with an MIT License copyright header. It demonstrates how license information can be expressed concisely at the top of a source file.

## Getting Started

Since this codebase has no external dependencies, no build system files (e.g., `pom.xml`, `build.gradle`), and no entry point class, there is no program to run. The recommended way to explore is:

1. **Browse `src/main/java/`** — all six source files live in this single directory.
2. **Start with `NoHeader.java`** — it's the simplest file (3 lines) and gives you the baseline before adding complexity.
3. **Read `WithHeader.java` next** — it shows a standard, idiomatic Java header format.
4. **Skim `MitLicense.java` and `PartialHeader.java`** — both are short files with useful real-world header patterns.
5. **Study `Crosslink.java`** — it introduces versioned inline markers for incremental code additions.
6. **Explore `LongHeader.java` last** — its 250+ line version history block is the most unusual and instructive example of how not *to* do versioning in practice (it's likely included to demonstrate a pattern that should be avoided).

The entire codebase is small enough to read end-to-end in a few minutes.