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Use the correct Java toolchain for every Maven project — automatically.
javaup (command: jup) is a Java toolchain manager built for Maven projects.
It detects the Java version required by a project, selects a matching installed
JDK, and remembers the project's Maven installation path, JDK, and optional
settings.xml. Every subsequent build reuses this toolchain, so there is no need
to change JAVA_HOME or PATH in the current shell or manually switch between
versions.
A development machine often hosts projects from several Java generations. Switching between them usually means changing environment variables, remembering which Maven installation to use, or relying on IDE settings that do not follow you into the terminal.
| Task | Without jup |
With jup |
|---|---|---|
| Switch projects | Edit JAVA_HOME and PATH |
Automatically reuse the JDK version saved for the project |
| Select Maven | Depend on whatever is on PATH | Automatically prefer the Wrapper or reuse saved Maven version |
| Use private repositories | Repeat --settings or replace a global file |
Automatically apply the project's settings alias |
| Build from anywhere | Change directories and reconstruct the environment | Automatically load the selected project's toolchain |
| Preserve the shell | Risk affecting later commands | Automatically isolate changes to the spawned build process |
jup complements existing Java tools instead of replacing them:
- SDKMAN!, asdf, and jEnv install or switch tools for a user or shell.
jupcan discover the JDKs they installed. - Maven Wrapper pins the Maven distribution for a repository.
jupdetects and prefers it automatically. - Maven Toolchains lets Maven plugins select a JDK.
jupalso discovers<jdkHome>entries and controls the JDK that launches Maven itself.
The layer jup adds is a local project binding: this Maven executable + this
JDK + this settings alias, launched through one stable command.
Important
jup selects JDKs and Maven installations that are already present. It does
not download or uninstall them. Apache Maven is the only supported build tool
in v0.3.0.
macOS or Linux:
curl -fsSL https://github.com/codeboyzhou/javaup/releases/latest/download/install.sh | shWindows PowerShell 5.1 or later:
irm https://github.com/codeboyzhou/javaup/releases/latest/download/install.ps1 | iexPrebuilt releases support Windows, macOS, and Linux on amd64 and arm64. See the
installation guide
for checksums, go install, source builds, and installer options.
The Maven project needs a pom.xml, Maven Wrapper or mvn on PATH, and a
matching full JDK installed locally.
cd /path/to/your/maven-project
jup init
jup status
jup run mvn clean packageIn an interactive terminal, jup run mvn can select any initialized project
and ranks frequently and recently used projects first. In CI or redirected
pipelines, it resolves the nearest initialized project without prompting.
- Detects Java requirements from POM properties, compiler plugin configuration, and local parent POMs.
- Prefers Maven Wrapper and falls back to Maven from PATH.
- Finds installed JDKs through Maven, environment variables, PATH, Maven Toolchains, and common platform locations.
- Applies the selected JDK and optional Maven settings alias only to the spawned build process.
- Manages and diagnoses initialized projects globally without modifying project source files.
Maven is currently the only supported build tool. JDKs and Maven must already be installed, and saved project/tool paths are local absolute paths. Maven settings aliases store paths only, never file contents or credentials. See the project scope for the complete boundaries.
Bug reports, compatibility cases, documentation improvements, and code contributions are welcome. Run the complete local verification pipeline with:
go mod download
go run build.go verifyRead CONTRIBUTING.md before submitting a pull request.
Licensed under the Apache License 2.0.