How do I get actual jar file and translator for J2ObjC?

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Summary

A developer attempted to use J2ObjC to translate GUI-less Java code to Objective-C but could not locate the required JAR file or translator executable. This is a common distribution and discovery issue when relying on older or discontinued open-source tools in a modern development environment. The core problem is not a technical failure in the tool itself, but rather the challenge of sourcing and maintaining dependencies for tools that are no longer actively distributed or supported by their original creators.

Root Cause

The inability to find the J2ObjC artifact stems from the project’s transition and eventual archiving by Google.

  • Project Archival: Google officially archived the J2ObjC project in late 2023. As a result, active development, official releases, and distribution channels were shut down.
  • Broken Distribution Links: The original project website and repository links likely point to deprecated pages or the archived repository, which no longer hosts pre-built binaries or a bat file for Windows.
  • Source-Only Availability: For many archived projects, the only remaining artifact is the source code itself. The “translator” is not a simple downloaded file but a build artifact that must be compiled from the source using tools like Bazel.

Why This Happens in Real Systems

This scenario is a classic example of supply chain entropy in software engineering.

  • Dependency Obsolescence: Teams often choose tools based on immediate functionality, overlooking the long-term maintenance model. When the upstream vendor (Google in this case) abandons a project, downstream consumers are left without support or easy-to-use binaries.
  • Ecosystem Evolution: The mobile development ecosystem has shifted significantly towards Kotlin Multiplatform and native SwiftUI/Compose. Tools like J2ObjC, which bridged Java and iOS, became less relevant, leading to their deprecation.
  • Build System Complexity: J2ObjC relied on Bazel, a complex build system not commonly used outside of specific Google-centric projects. This creates a high barrier to entry for users who simply want a jar file to run on the command line.

Real-World Impact

Failure to resolve this dependency issue leads to direct project blockers and wasted engineering time.

  • Development Halt: The primary impact is a blocker for code sharing initiatives. The team cannot proceed with their plan to reuse Java logic on iOS, forcing a complete rewrite or a search for an alternative architecture.
  • Wasted Investigation Time: Hours are lost searching repositories, reading archived documentation, and attempting to configure build environments (like Bazel) just to acquire a tool that was previously available as a single executable.
  • Increased Maintenance Risk: If the developer manages to build the tool from source, they are now the maintainer of that build process. They are susceptible to bit rot, incompatible compiler updates, and unpatched security vulnerabilities in the aging codebase.

Example or Code

Since the tool is not available as a pre-built artifact, no direct code translation is possible. However, the discovery process usually involves checking the official repository status.

# The typical dead end a developer hits when looking for the binary:
curl -I https://github.com/google/j2objc/releases/latest

# Checking the README often confirms the archival status
git clone https://github.com/google/j2objc.git
cd j2objc
cat README.md
# Output likely indicates: "This project is no longer maintained."

How Senior Engineers Fix It

A senior engineer addresses the root cause (availability and sustainability) rather than the symptom (missing file).

  • Abandon the Legacy Tool: The correct fix is to stop looking for the J2ObjC binary. Accept that the tool is effectively deprecated and build a bridge to the archived repository only if legacy maintenance is required.
  • Adopt Modern Alternatives: Pivot the architecture to use currently supported tools.
    • Use Kotlin Multiplatform (KMP) to share business logic between Java (Android) and iOS (Swift/Obj-C).
    • Implement a REST/gRPC API to decouple the backend logic entirely from the client platforms.
  • Vendor or Fork: If the tool is absolutely mandatory, clone the source repository and build it locally using Bazel. Then, host the resulting artifacts on a private artifact server (e.g., Artifactory or Nexus) to stabilize the supply chain for the rest of the team.

Why Juniors Miss It

Junior developers often lack the context of the software lifecycle.

  • Expectation of Availability: Juniors are accustomed to the modern npm/Maven ecosystem where packages are almost always available. They often assume a missing file is a “bug” or a broken link rather than a signal that the project is dead.
  • Lack of “Reading the Room”: They may miss the red flags in the repository (e.g., “Archived” tags, lack of commits for years, closed issues) and continue trying to force the tool to work.
  • Focus on Syntax over Tooling: Juniors focus heavily on “Will this translate my code?” rather than “Is this tool supported in my current environment?” They often don’t realize that the translation engine (the JAR) is complex to build without the exact environment the authors used.