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javaup documentation
Project-Aware Java Toolchains for Maven Builds
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  1. Welcome to the javaup documentation
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Welcome to the javaup documentation

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.

jup selects toolchains that are already installed. It does not download or uninstall JDKs or Maven. Apache Maven is the only supported build tool in v0.3.0.

Why javaup?

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. jup can discover the JDKs they installed.
  • Maven Wrapper pins the Maven distribution for a repository. jup detects and prefers it automatically.
  • Maven Toolchains lets Maven plugins select a JDK. jup also 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.

Highlights

  • Detects Java requirements from POM properties, compiler plugin configuration, and local parent POMs.
  • Prefers Maven Wrapper and falls back to Maven from PATH.
  • Discovers installed JDKs across environment variables, PATH, Maven Toolchains, and common installation locations.
  • Runs builds with a project-specific child-process environment while leaving the current shell unchanged.
  • Manages initialized projects globally and ranks them by recent use.
  • Diagnoses stale Maven, JDK, POM, and settings configuration.
  • Supports Windows, macOS, and Linux.

Start with Installation and Quick Start, or open the Command Reference.