java-preloader-reloadeder

Replacement for my old gist.

Downloads JDKs from Adoptium into <cache dir>/jpre/jdks, then sets a symlink to the currently active JDK. The symlinks are per-TTY (which usually implies per-shell), and stored in the Rust-std-determined temporary folder, which is usually $TMPDIR or /tmp.

Installation

Run cargo install jpre to get the jpre binary, and set your JAVA_HOME to $(jpre java-home).

For most people adding this is enough:

# Retrieves the TTY-specific path and stores it in JAVA_HOME. This will be symlinked to the currently active JDK.
export JAVA_HOME="$(jpre java-home)"
# Puts the binaries on your path
export PATH="$JAVA_HOME/bin:$PATH"
# Potentially optional, forces shell to re-scan for `java` et. al
hash -r

Note that if you do not set a default JDK, the symlinked path will lead nowhere!

Usage

Run jpre use 11, this downloads JDK 11 from Adoptium and makes it the active JDK. Other major versions can be downloaded and configured using jpre use <major>. The default JDK can be set using jpre default <major>.

Full details are available by running jpre help.

Known Limitations

Since this is per-TTY, closing and re-opening a terminal tab / window may result in a different JDK than the default, due to TTY reuse.