javaup

Project-aware Java toolchains for Maven builds

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The right JDK, the right Maven, and the right settings.xml for every project build.

javaup (command: jup) detects the Java version required by a Maven project, finds a matching installed JDK, and remembers the Maven executable, JDK, and optional settings.xml selection for that project. It recreates the saved toolchain whenever you build, without changing JAVA_HOME or PATH in your current shell.

$ cd myproject
$ jup init
[1/5] Project OK - /work/myproject
[2/5] Build Tool OK - Maven 3.9.11 (wrapper)
[3/5] Java Version OK - Java 8
[4/5] JDK OK - Java 1.8.0_472 at /opt/jdks/temurin-8
[5/5] Config OK - /home/alex/.javaup/config/projects/...
Initialized javaup project.

$ jup run mvn test
[INFO] BUILD SUCCESS

Important

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 v0.2.0.

Why javaup?

A single development machine often hosts projects from several Java generations: a legacy application on Java 8, a current service on Java 17, and a newer repository on Java 21. 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.

With jup, each project gets one explicit, inspectable toolchain:

Task	Without jup	With jup
Switch projects	Edit JAVA_HOME and PATH	Use the JDK saved for the project
Select Maven	Depend on whatever is on PATH	Prefer the project Wrapper, otherwise save Maven from PATH
Use private repositories	Repeat --settings or replace a global file	Bind a named settings.xml to the project
Build from a submodule	Return to the root and reconstruct the environment	Resolve the initialized project from any descendant directory
Preserve the shell	Risk affecting later commands	Change only the spawned build process

How it fits with existing tools

javaup complements JDK version managers and Maven's own tooling:

• SDKMAN!, asdf, and jEnv install or switch tools for a user or shell. jup does not replace them; it can discover the JDKs they installed.
• Maven Wrapper pins the Maven distribution for a repository. jup detects and prefers the Wrapper automatically.
• Maven Toolchains lets Maven plugins select a JDK. jup can discover <jdkHome> entries from ~/.m2/toolchains.xml and also controls the JDK that launches Maven itself.

The useful layer jup adds is a local project binding: **this Maven executable

• this JDK + this settings alias**, launched through one stable command.

Install

macOS or Linux

curl -fsSL https://github.com/codeboyzhou/javaup/releases/latest/download/install.sh | sh

The installer detects the operating system and architecture, verifies the release checksum, installs jup under ~/.javaup/bin, and updates the relevant shell profile.

Windows

Run in PowerShell 5.1 or later:

irm https://github.com/codeboyzhou/javaup/releases/latest/download/install.ps1 | iex

The installer verifies the release checksum, installs jup.exe under %USERPROFILE%\.javaup\bin, and adds that directory to the user PATH.

Prefer to inspect the files first? Download an archive, checksum, or installer from GitHub Releases. Prebuilt binaries are available for Windows, macOS, and Linux on amd64 and arm64.

Other installation options

Install with the Go version declared in go.mod, or newer:

go install github.com/codeboyzhou/javaup/cmd/jup@latest

Or build from source:

git clone https://github.com/codeboyzhou/javaup.git
cd javaup
go run build.go

The binary is written to dist/jup.exe on Windows or dist/jup on macOS and Linux.

The installers support these optional environment variables:

Variable	Purpose
JAVAUP_VERSION	Install a specific release, such as v0.2.0
JAVAUP_HOME	Use a custom absolute installation and configuration directory
JAVAUP_NO_MODIFY_PATH	Install without updating the shell profile or user PATH

Verify the installation:

jup version

Quick start

Before starting, the Maven project must have a pom.xml, a Maven Wrapper or mvn on PATH, and an installed full JDK matching the project's Java version.

Initialize, inspect, and build:

cd /path/to/your/maven-project
jup init
jup status
jup run mvn clean package

Example status:

Project: /work/demo
Build tool: Maven 3.9.11 (wrapper)
Build executable: /work/demo/mvnw
Java version: 17.0.12
Java home: /opt/jdks/temurin-17
Maven settings: default

jup run mvn connects Maven directly to the current terminal, preserving interactive input, logs, and exit codes. It starts Maven in the current directory, so module-specific builds work as expected.

Highlights

• Detects the Java release from pom.xml, compiler plugin configuration, properties, and local parent POMs.
• Detects mvnw / mvnw.cmd and falls back to Maven from PATH.
• Finds installed JDKs through Maven, environment variables, PATH, Maven Toolchains, common installation locations, and sibling JDK directories.
• Saves the Maven executable, JDK path, versions, and initialization time per project.
• Sets JAVA_HOME and puts the selected JDK's bin first on PATH only for the spawned build process.
• Binds reusable Maven settings.xml aliases to individual projects.
• Resolves status, run, settings use/unset, and uninit from any descendant directory.
• Runs on Windows, macOS, and Linux, with CI verification on all three.

Maven settings aliases

Register settings files once, then select one per project:

jup settings add intranet /path/to/settings-intranet.xml
jup settings add public /path/to/settings-public.xml

cd /path/to/company-project
jup settings use intranet
jup run mvn clean deploy

jup saves only the normalized file path. It does not copy the XML file or its credentials. Use jup settings unset to return a project to Maven's default settings.

Command overview

Command	Purpose
jup init	Detect and save the current project's Maven and JDK
jup status	Show the saved toolchain
jup run mvn <args...>	Run Maven with the saved toolchain
jup settings add <alias> <file>	Register or update a settings alias
jup settings list	List settings aliases
jup settings use <alias>	Bind an alias to the current project
jup settings unset	Remove the project's settings binding
jup settings remove <alias>	Remove a global alias
jup uninit	Remove the project's saved jup configuration
jup uninstall	Uninstall jup while preserving configuration
jup uninstall --purge	Uninstall jup and remove all javaup data
jup update --check	Check whether a newer release is available
jup update	Download, verify, and install the latest release

See the full user guide for detection rules, configuration storage, detailed command behavior, and troubleshooting.

Project status and scope

v0.2.0 adds built-in, checksum-verified self-update and safe uninstall workflows. Release archives are built for Windows, macOS, and Linux on amd64 and arm64, and every archive is covered by a published SHA-256 checksum.

Current boundaries:

• Maven is the only supported build tool; Gradle is not yet supported.
• JDKs and Maven must already be installed locally.
• Project configuration is local to the current user and is not written to the repository.
• Saved JDK and Maven locations are absolute paths; run jup init again after moving a tool or project.
• Maven settings aliases store paths, not file contents or credentials.

If javaup cannot handle a real project, please open an issue with the operating system, POM structure, expected Java version, and relevant command output.

Documentation

• User guide — commands, detection, storage, and troubleshooting
• Contributing guide — development setup, verification, and project layout
• Simplified Chinese README
• Simplified Chinese user guide

Contributing

Bug reports, compatibility cases, documentation improvements, and code contributions are welcome. To run the complete local verification pipeline:

go mod download
go run build.go verify

Read CONTRIBUTING.md before submitting a pull request.

License

Licensed under the Apache License 2.0.