jEnv is a command-line tool that empowers developers to manage multiple Java environments with surgical precision. Unlike heavy-duty installers, jEnv follows the 'rbenv' philosophy, utilizing a shims-based architecture to intercept Java commands and route them to the appropriate JDK version based on the current directory or shell context. In the 2026 landscape, where enterprises often juggle legacy Java 8 microservices alongside modern Java 25+ reactive architectures, jEnv serves as the critical abstraction layer that prevents 'JAVA_HOME' pollution. It integrates deeply with common build tools like Maven and Gradle via a dedicated plugin system, ensuring that not only the compiler but the entire toolchain respects the environment's versioning requirements. By leveraging a simple '.java-version' file within project roots, jEnv enables seamless team-wide synchronization of development environments without the overhead of containerization for every local task. Its lightweight footprint and zero-dependency runtime make it the preferred choice for macOS and Linux power users who require high-performance JDK switching across Zsh, Bash, and Fish shells.
Uses lightweight executable wrappers (shims) to intercept and redirect Java calls to the correct binary version.
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Detects a .java-version file in the current or parent directory to automatically switch the JDK.
Includes built-in plugins for Maven, Gradle, Ant, and SBT to ensure these tools use the jEnv-selected JDK.
Provides full compatibility with Bash, Zsh, and Fish through dynamic shell initialization scripts.
Allows setting a fallback JDK version at the user level when no local configuration is found.
Enables renaming complex JDK paths into human-readable versions like 'openjdk-21'.
The 'export' plugin dynamically updates the JAVA_HOME variable every time the directory changes.
A developer needs to work on a Java 8 project and a Java 21 project simultaneously without manual PATH changes.
Registry Updated:2/7/2026
Observe the version switch automatically when jumping between tabs.
Team members have different JDK paths on their local machines causing CI inconsistencies.
Maven often ignores system PATHs and uses its own bundled or default Java version.