Java Compiler & IDE Editor

Write, compile, and run Java 17 code directly on your Android device. Fully offline.

Java Compiler & IDE Editor is a complete Java development environment in your pocket. No internet required, no cloud sign-up, no remote execution — everything runs on-device with an embedded Java runtime.

WHAT YOU CAN DO

• Compile and run real Java programs offline, from single files to multi-class projects
• Use modern Java 17 features — records, sealed types, pattern matching, switch expressions, text blocks
• Experiment in Notebook mode — Jupyter-style cells, keep variables alive between runs
• Install popular libraries with one tap — Apache Commons Lang3, Commons IO, Gson, OkHttp, Jsoup
• Import your own JAR files and add them to the classpath
• Run a local web server from Java code — extend WebApp, open the URL in any browser
• Code comfortably in 15 languages with a dark-first, distraction-free editor

EDITOR
Syntax highlighting, auto-indent, line numbers, bracket matching, find and replace, multi-file projects, and a file tree that understands Java packages. Undo/redo with deep history. Readable monospace fonts tuned for small screens.

NOTEBOOK MODE
Break your code into runnable cells. Great for learning, quick experiments, and debugging logic step-by-step. Cell state persists — define a class in cell 1, use it in cell 10. Export notebooks as standard .java files any time.

LIBRARIES
Free picks bundled for instant use: Apache Commons Lang3 (string and object utilities), Commons IO (file helpers), Gson (JSON parsing), OkHttp (HTTP client), Jsoup (HTML parsing). Maven Central search and unlimited libraries available with the optional Pro upgrade.

IMPORT JARS
Bring your own .jar files from anywhere on your device. Added to the classpath automatically. Useful for learning from existing code, testing your own packaged libraries, or running community tools.

WEB SERVER MODE
Write a class that extends WebApp, hit Run, and the app starts a local web server on your device. Open the link in Chrome or any browser to see your output. Perfect for learning servlet-style Java or prototyping small web tools offline.

THEMES AND CUSTOMIZATION
Dark-first themes out of the box. Adjust font size, line spacing, and indent width. Additional Pro themes available with the optional upgrade.

WHO IT'S FOR
• Computer science and engineering students learning Java
• Self-taught learners following Java tutorials on the go
• Developers who want to prototype a class or algorithm without opening a laptop
• Interview prep — practise DSA in real Java on your phone
• Anyone who wants a reliable offline Java editor that runs real code

FREE AND OPTIONAL PRO UPGRADE
Free to install and use. Shows ads to support development. A one-time Pro upgrade removes ads, unlocks Maven Central library search, and unlocks Pro themes — no subscription, no recurring charges.

LANGUAGES
UI available in 15 languages including English, Spanish, Portuguese, French, German, Russian, Hindi, Bengali, Indonesian, Turkish, Urdu, Arabic, Chinese (Simplified), Japanese, and Korean.

Recent changes:
Java/Kotlin language toggle now reliably switches the editor and inserts the right starter code. Toolbar reorganised so it scrolls cleanly on every screen size. Home shows separate Java and Kotlin examples sections plus a quick-start picker for new files. Kotlin code can be edited and saved while the runtime is in development.