JMAN Java
Native Java language support backed by JMAN's Rust language server and GraalVM
compiler frontend. JMAN Java understands JMAN, Maven, and Gradle workspaces and
keeps editor analysis aligned with the project's real build model.
Preview: this release supports 64-bit glibc-based Linux systems. Windows,
macOS, ARM, Alpine Linux, virtual workspaces, and untrusted workspaces are not
supported yet.
Highlights
- Java diagnostics, completion, hover, signature help, navigation, references,
symbols, semantic highlighting, inlay hints, formatting, and code actions.
- Workspace import for
jman.toml, Maven, and Gradle projects.
- Native VS Code Test Explorer integration for unit and integration tests.
- Commands for project checks, builds, runs, tests, synchronization, indexing,
cache maintenance, server status, and restart.
- A bundled
jman server: no separate JMAN installation is required for normal
extension operation.
Requirements
- Visual Studio Code 1.95 or newer.
- A 64-bit x86 processor and Linux distribution using glibc.
- A Java 25 GraalVM installation for the compiler frontend and Java workers.
- A trusted local or remote workspace with its project dependencies available.
JMAN may invoke a Maven or Gradle wrapper when importing those project types.
The wrapper and repositories must therefore be usable from the extension host.
For Gradle wrappers, JMAN selects the newest installed LTS JDK that the wrapper
can run on. This build-tool runtime is independent from the Java 25 GraalVM
used by the native compiler frontend, and JMAN never installs a JDK implicitly.
Getting started
- Install JMAN Java from the Visual Studio Marketplace.
- Open a trusted folder containing
jman.toml, pom.xml, build.gradle, or
build.gradle.kts.
- Set
jman.java.javaHome to your Java 25 GraalVM installation.
- Open a Java source file and run JMAN Java: Show Status from the Command
Palette to confirm the selected build system and index state.
Example workspace settings:
{
"jman.java.javaHome": "/path/to/graalvm-jdk-25",
"jman.java.buildJavaHome": "",
"jman.java.buildSystem": "auto",
"jman.java.buildSync": "prompt"
}
Project selection
The default auto mode uses JMAN when jman.toml is present, then detects
Gradle or Maven. Select a build system explicitly when a workspace contains
metadata for more than one build tool.
| Setting |
Default |
Purpose |
jman.java.server.path |
bundled server |
Override the jman executable used by the extension. |
jman.java.javaHome |
empty |
Select the Java 25 GraalVM installation used by JMAN. |
jman.java.buildJavaHome |
empty |
Override the JDK used to run Maven or Gradle; empty lets Gradle select a compatible installed runtime. |
jman.java.buildSystem |
auto |
Choose auto, jman, gradle, or maven. |
jman.java.buildSync |
prompt |
Choose manual, prompt, or automatic synchronization. |
jman.java.server.extraEnv |
{} |
Add environment variables to the language-server process. |
Commands
| Command |
Purpose |
| JMAN Java: Show Status |
Show server, workspace, index, cache, and synchronization state. |
| JMAN Java: Sync Workspace |
Reload the selected project model. |
| JMAN Java: Check Project |
Compile and check the workspace. |
| JMAN Java: Build Project |
Build reproducible project outputs. |
| JMAN Java: Run Application |
Run the configured application. |
| JMAN Java: Run All Tests |
Run the complete test suite. |
| JMAN Java: Change Method Signature |
Apply JMAN's conservative change-signature refactoring. |
| JMAN Java: Rebuild Project Index |
Recreate the Java symbol index. |
| JMAN Java: Clear Workspace Cache |
Clear cached project data and rebuild it. |
| JMAN Java: Restart Server |
Restart the bundled language server. |
Individual tests and classes can also be run from VS Code's Test Explorer and
from test code lenses.
Compatibility and limitations
JMAN Java is an early preview. Maven and Gradle model import intentionally does
not execute arbitrary build plugins inside the language-server process. Rename
and change-signature operations are conservative, and some framework-generated
or reflective references may not yet be discovered.
Running multiple Java language servers for the same workspace can produce
duplicate diagnostics, competing code actions, and excess resource usage.
Disable other Java language-server extensions in the workspace while evaluating
JMAN Java.
Privacy and network access
The extension does not collect or transmit analytics or telemetry. JMAN and the
selected build tool may access configured artifact repositories, wrapper
distributions, and the Adoptium API when a requested project or toolchain
operation requires them. Environment variables configured through
jman.java.server.extraEnv are passed to the JMAN process; do not place secrets
in settings that you would not normally expose to a local build tool.
Troubleshooting
Open View → Output → JMAN Java for server startup and protocol diagnostics.
If startup fails, verify the configured GraalVM path, confirm the project wrapper
is executable, and run the corresponding build tool from a terminal. Use
JMAN Java: Show Status to inspect synchronization and indexing failures.
If no installed JDK can run the Gradle wrapper, install the suggested version
with jman java install <major> or set jman.java.buildJavaHome. This setting
changes the build-tool runtime only; Gradle still owns the project's compiler
toolchain and target release.
Report reproducible problems through GitHub Issues.
Include the JMAN Java version, VS Code version, Linux distribution, selected
build system, and sanitized output-channel logs. See SUPPORT.md
before reporting security-sensitive information.
License
JMAN Java is licensed under the Apache License 2.0. Bundled third-party software
retains its own license; see THIRD_PARTY_NOTICES.md.
