Java (JDK/JRE)

Installation

Java 11 on Fedora:

$ sudo dnf install java-11-openjdk-devel

Tuning and profiling

Using Java Mission Control on Mac OS X:

                  $ find /Library/Java -name jmc
$ jmc &

# Now run your application with these JVM flags
$ java -XX:+UnlockCommercialFeatures -XX:+FlightRecorder -jar myapp.jar

Cookbook

Default Java Home on Mac (symlinked): /Library/Java/Home
Other Java Homes located at: /Library/Java/JavaVirtualMachines/jdk1.x.y_nn.jdk/Contents/Home

List Java Homes on a Mac:

/usr/libexec/java_home -V

JARs

Extract a file to stdout:

                  jar xvf myjar.jar META-INF/MANIFEST.MF
cat META-INF/MANIFEST.MF

Or on Linux:

unzip -p myjar.jar META-INF/MANIFEST.MF

Jenv

Install Jenv to manage multiple versions

brew install jenv

Install jenv for zsh:

                  echo 'export PATH="$HOME/.jenv/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(jenv init -)"' >> ~/.zshrc

Add JVMs:

                  jenv add /Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home/
jenv add /Library/Java/JavaVirtualMachines/jdk1.8.0_74.jdk/Contents/Home/

Set Java version for a specific project path:

jenv local