Bug Gym
Offline Java exam practice with native testing on Windows, macOS, and Linux
A cross-platform Java learning environment that recreates the constraints of Moodle programming exams while adding automated feedback, structured exercises, and local progress tracking—without accounts, internet access, or a full IDE.
The 15-second brief
At a glance
- Outcome
- Closed the practice gap between Moodle exams and general-purpose IDEs with a focused, offline workflow distributed across three desktop platforms.
- Delivery
- Shipped, 2026 · Personal
- Focus
- Full-Stack, Desktop
- Scope
- 7 core technologies
- Installs
- 130+GitHub releases, as of Sep 2026
- Platforms
- 3
- Releases
- 5
Ownership and evidence
What I built
The product decisions and engineering work that shaped the final result.
Engineered an in-memory Java compilation and execution pipeline that runs submitted solutions and evaluates them against automated input/output tests.
Separated learning content from application code through Markdown-based problem definitions, making exercises readable, versionable, and straightforward to extend.
Built a RichTextFX editor with syntax highlighting, line numbers, adjustable presentation, and an intentionally constrained exam-style workflow.
Implemented character-level output comparison, clear compiler/runtime feedback, and a five-second per-test timeout so beginners can diagnose failures without opaque tooling errors or frozen runs.
Automated native releases through GitHub Actions and jpackage for Windows, macOS, and Linux.
Kept progress and application state local, preserving fast startup and fully offline operation.
Product evidence
See it in action
Interface views and demonstrations from the working product.
Question editor with instant feedback Offline-first practice dashboard