Detection Rules

Project Root

jup init uses the current directory and requires pom.xml there. After initialization, project-aware commands search upward from any descendant. Paths, symbolic links, and Windows long-path/8.3-path variants are normalized so one project does not produce multiple configurations.

Maven Selection

If the project contains mvnw or mvnw.cmd, jup saves the Wrapper. Otherwise it finds mvn or mvn.cmd on PATH. The resolved executable and reported Maven version are stored with the project.

Java Version Detection

POM values are evaluated in this order, with ${property} references resolved:

<release> in maven-compiler-plugin;
maven.compiler.release;
<target> in maven-compiler-plugin;
maven.compiler.target;
<source> in maven-compiler-plugin;
maven.compiler.source;
java.version;
jdk.version.

When a local parent POM exists, jup follows <relativePath> for up to 16 parent levels.

JDK Discovery

Candidates are checked in this order; the first full JDK whose Java major version matches the project is selected:

the JDK reported by the Maven runtime;
JAVA_HOME, JDK_HOME, and variables such as JAVA8_HOME or JAVA_HOME_17;
the JDK that owns javac on PATH;
sibling directories of known JDKs;
<jdkHome> entries in ~/.m2/toolchains.xml;
platform locations such as Program Files/Java, ~/.jdks, SDKMAN!, Homebrew, and asdf.

A candidate must contain bin/javac (bin/javac.exe on Windows). Its version comes from the JDK release file when possible, with javac -version as a fallback.