2.1 Introduction To Toolchain

Modern Java development requires more than just writing code. A professional toolchain ensures reproducible builds, consistent dependency management, reliable packaging, and deployment flexibility. This chapter covers the essential tools and practices for building, packaging, and distributing Java 25 applications.

What You'll Learn

  • Build Tools: Maven and Gradle for reproducible, automated builds
  • Dependency Management: Controlling versions, managing transitive dependencies, and security
  • Java Module System (JPMS): Strong encapsulation, reliable configuration, and modular architecture
  • Custom Runtime Images: Using jlink to create minimal, trimmed JDK installations
  • Native Installers: Using jpackage to distribute platform-specific installers for end users
  • Best Practices: Versioning, signing, and deployment strategies

The Java Build Ecosystem

The journey from source code to production involves several stages:

  1. Compilation: Source code (.java) → Bytecode (.class)
  2. Packaging: Compiled classes → Distributable artifacts (JAR, WAR, custom images)
  3. Dependency Resolution: Locating and downloading required libraries
  4. Testing: Unit and integration tests within the build lifecycle
  5. Distribution: Delivering artifacts to users or deployment environments

Build Tools

Maven (XML-based) and Gradle (DSL-based) automate these stages:

  • Define project structure, dependencies, and build phases
  • Run tests automatically
  • Generate documentation and reports
  • Publish artifacts to repositories

Modular Architecture

The Java Platform Module System (JPMS), introduced in Java 9, lets you organize code into modules with explicit dependencies and strong encapsulation. This prevents accidental coupling and enables:

  • Reliable Configuration: Module dependencies are explicit and checked at compile time
  • Strong Encapsulation: Only exported packages are visible to other modules
  • Custom Runtime Images: jlink removes unused modules to reduce deployment size

Packaging and Distribution

Modern Java applications deploy as:

  • Fat JARs for simple microservices
  • Modular JARs for larger applications with JPMS
  • Custom Runtime Images for containerized deployment
  • Native Installers (pkg, deb, msi) for end-user applications

Chapter Structure

The following sections provide practical guidance on each aspect:

  1. Maven and Gradle: Deep dive into build configuration, lifecycle, and best practices
  2. Dependency Management: Strategies for resolving, pinning, and updating dependencies securely
  3. JPMS Modules: Designing modular applications with the Java Platform Module System
  4. jlink and jpackage: Creating trimmed runtime images and native installers
  5. Deploying Java Applications: From JAR to containers, cloud, and native distribution

By mastering these tools, you'll build Java applications that are:

  • Reproducible: Same inputs always produce identical outputs
  • Maintainable: Clear structure, explicit dependencies
  • Efficient: Minimal size, fast startup with custom runtimes
  • Distributable: Easy to deploy across platforms and environments