# google/j2objc

A Java to iOS Objective-C translation tool and runtime.

Repository: https://github.com/google/j2objc
Canonical: https://ross.abutalabs.com/products/j2objc
Homepage: http://j2objc.org
Language: Java
License: NOASSERTION
License Family: other
Last push: 2026-08-26T21:33:32+00:00

## Health v2 (maintenance only)
Score: 68/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 10, longevity 100
- inputs: {"age_days": 4598, "days_push": 7, "days_rel": 384, "gap_med": null, "n_releases_24m": 1}
- flags: prerelease_only, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 6039, forks 999 (observed 2026-08-28T04:09:34.522819+00:00)

## What it is
J2ObjC is Google's open-source command-line translator that converts Java source code into Objective-C for iOS apps, with a supporting runtime. It lets developers share non-UI Java code (logic and data models) across Android, iOS, and web (GWT/J2CL) applications.

## Use cases
- share Java business logic in an iOS app
- translate Java source code to Objective-C
- reuse Android app data models on iPhone
- run JUnit tests translated to Objective-C
- build cross-platform apps without rewriting non-UI code

## When to choose
- you have existing Java source for app logic and want it in an iOS app
- you want to share non-UI code between Android and iOS
- you can build on a Mac with Xcode and JDK 21

## When to avoid
- you need a cross-platform UI toolkit - it only translates non-UI code
- you only have Android binary APKs rather than source code
- you need production-grade stability - it is beta quality
- you develop on Linux or Windows - it requires macOS

## Facets
- artifact type: cli-tool
- maturity: maintenance
- function: compiler, developer-tools, testing
- domain: cross-platform, mobile-development, developer-tools, compilers
- platform: cli
- tags: java-to-objective-c, code-translation, ios-development, code-sharing, transpiler, macos, ios

## Member repositories
- google/j2objc (main) score 68

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:34.522819+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:48:58.343160+00:00, confidence not recorded.
  - readme: https://github.com/google/j2objc (fetched 2026-08-28T04:09:34.522819+00:00, sha cfb2a6295a41)
  - homepage: http://j2objc.org (fetched 2026-08-29T08:45:16.372496+00:00, sha ee24cad9fc81)
- Data as of 2026-08-30T08:39:29.467469+00:00.