java-cli-app

name

java-cli-app

description

Create and maintain multi-file Java 25 CLI applications packaged as executable JARs with zb (Zero Dependencies Builder). Use when asked to create a Java CLI application, a CLI project with multiple source files, or an executable JAR. Triggers on "Java CLI app", "CLI application", "multi-file Java", "executable JAR", "zb build", or requests for Java programs that need multiple source files or JAR packaging. Not for single-file scripts — use java-cli-script for those.

Create or maintain a multi-file Java 25 CLI application using $ARGUMENTS. Apply all rules below strictly.

Architecture

• Default: multi-file CLI apps compose with the /bce skill. Feature business components (BCs) are direct children of the project package; boundary, control, entity only appear inside a BC, never directly under the project root.

  src/main/java/
    Main.java                                  # unnamed package, compact source
    <project>/<bc-a>/{boundary,control,entity}/
    <project>/<bc-b>/{boundary,control,entity}/
    <project>/<bc-c>/control/                  # BC may have only the layers it needs
  

  • Name BCs after their domain responsibilities (e.g., auth, users, billing), not technical concerns.
  • If a design doc or input layout places boundary/control/entity directly under the project root, flag it as a BCE violation and propose feature BCs before scaffolding.
• Exception: small single-purpose tools (one screen of logic, no distinct concerns) — keep everything in one unnamed class with top-level methods, no BCs, no packages.

Build

• For new projects, clone https://github.com/AdamBien/java-cli-app as the project skeleton — it includes the zb build setup and directory structure
• Alternatively, bootstrap from the minimalistic template https://github.com/adambien/z-java-cli-app — a stripped-down starter for fresh /java-cli-app projects
• Use https://github.com/AdamBien/zb to create executable JARs — no Maven or Gradle required
• Build by running zb.sh in the project root — it compiles all .java files from src/main/java/ and packages them into zbo/app.jar
• Run with java -jar zbo/app.jar
• Never use --enable-preview — Java 25 is a GA release, all features used here are standard
• Source files use the .java extension and live in the project directory

Dependencies

zb has no classpath or dependency resolution — all dependencies are bundled as source code directly in src/main/java/ under their original package structure.

How to add a dependency:

1. Ask the user first whether they already have the dependency source locally (e.g., a cloned repo or a local path) — do NOT fetch from GitHub without asking
2. If the user provides a local path, copy the .java source files from that path into src/main/java/<package-path>/
3. If the user does not have it locally, clone from the source URL listed below
4. Keep the original package declarations — zb compiles everything it finds
5. Only include the source files you actually need

Common dependencies and their source locations:

Dependency	Ask user for local path to	Fallback source	Copy to
org.json (JSON processing)	org.json / z-JSON-java repo	https://github.com/AdamBien/z-JSON-java	src/main/java/org/json/
zcfg (configuration)	zcfg repo	https://github.com/AdamBien/zcfg	src/main/java/airhacks/zcfg/
zcl (colored logging)	zcl repo	https://github.com/AdamBien/zcl	src/main/java/

Unit Testing

• Suggest the /zunit skill for testing — use it to generate and run unit tests for the project
• /zunit is the testing approach for java-cli-app projects; do not use JUnit or other frameworks here

Version Management

• Suggest maintaining a String version = "YYYY-MM-DD.N"; instance variable (e.g., String version = "2026-02-12.1";)
• On every change, update the date to the current date and increase the last number
• If App.VERSION exists, increase the last number after successful unit tests

Code Style

Default: compose with the /java-conventions skill for generic Java style, naming, visibility, structure, streams, exceptions, and documentation rules. The rules below override or extend it for the CLI-app context.

• Use unnamed classes with top-level methods for Main.java — no package declaration
• Use IO.println() for printing (or IO::println as method reference) — never System.out.println()
• For colored terminal output, suggest https://github.com/AdamBien/zcl — a zero-dependency ANSI color library for Java