Using multiple versions of Java with Brew on Mac + jEnv

Homebrew installation

--See Homebrew site - https://brew.sh

Introduction of homebrew-cask-versions

• https://github.com/Homebrew/homebrew-cask-versions --Required for installation other than the latest version.

$ brew tap homebrew/cask-versions

Java 14 installation

--Java installed by cask install java will be the latest version (currently Java SE 14).

$ brew cask install java

Java 11 installation

$ brew cask install java11

Java 8 installation

--__ Not available due to license. AdoptOpenJDK, Corretto, [Zulu](https://jp.azul.com/downloads/ Substitute with zulu /) etc. __ -The SDK included differs depending on the JDK, so be careful.

$ brew cask install java8

Install AdoptOpenJDK 8

$ brew cask install adoptopenjdk8

Installing Amazon Corretto 8

$ brew cask install corretto8

Install Zulu 8

$ brew cask install zulu8

Check the installed JDK (JAVA_HOME)

--/ usr / libexec / java_home command

$ /usr/libexec/java_home -V
Matching Java Virtual Machines (3):
    12.0.1, x86_64:	"OpenJDK 12.0.1"	/Library/Java/JavaVirtualMachines/openjdk-12.0.1.jdk/Contents/Home
    11.0.2, x86_64:	"OpenJDK 11.0.2"	/Library/Java/JavaVirtualMachines/openjdk-11.0.2.jdk/Contents/Home
    1.8.0_212, x86_64:	"AdoptOpenJDK 8"	/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/openjdk-12.0.1.jdk/Contents/Home
$ /usr/libexec/java_home --help
Usage: java_home [options...]
    Returns the path to a Java home directory from the current user's settings.

Options:
    [-v/--version   <version>]       Filter Java versions in the "JVMVersion" form 1.X(+ or *).
    [-a/--arch      <architecture>]  Filter JVMs matching architecture (i386, x86_64, etc).
    [-d/--datamodel <datamodel>]     Filter JVMs capable of -d32 or -d64
    [-t/--task      <task>]          Use the JVM list for a specific task (Applets, WebStart, BundledApp, JNI, or CommandLine)
    [-F/--failfast]                  Fail when filters return no JVMs, do not continue with default.
    [   --exec      <command> ...]   Execute the $JAVA_HOME/bin/<command> with the remaining arguments.
    [-R/--request]                   Request installation of a Java Runtime if not installed.
    [-X/--xml]                       Print full JVM list and additional data as XML plist.
    [-V/--verbose]                   Print full JVM list with architectures.
    [-h/--help]                      This usage information.

JDK switching

--Switch Java version on OS X --Set the environment variable JAVA_HOME using the java_home command. --Add to the .bashrc and .zshrc files according to the shell you are using.

Java SE 14

$ export JAVA_HOME=`/usr/libexec/java_home -v "14"`
$ PATH=${JAVA_HOME}/bin:${PATH}

Java SE 11

$ export JAVA_HOME=`/usr/libexec/java_home -v "11"`
$ PATH=${JAVA_HOME}/bin:${PATH}

Java SE 8

$ export JAVA_HOME=`/usr/libexec/java_home -v "1.8"`
$ PATH=${JAVA_HOME}/bin:${PATH}

Use of jEnv

--By introducing jEnv, it becomes easy to switch Java versions. --Reference: https://github.com/jenv/jenv

Install jEnv

--Install with Homebrew

$ brew install jenv

--Set PATH --Note that it depends on the shell used.

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

--Create a directory

$ cd ~
$ mkdir ~/.jenv/versions

Add JDK to jEnv

--Install the JDK with Homebrew Cask. --Add the installed JDK to jEnv.

Addition of Java 8

$ jenv add `/usr/libexec/java_home -v "1.8"`

List of JDKs added to jEnv

--The JDK with * at the beginning is enabled.

$ jenv versions
* system (set by /Users/[User name]/.jenv/version)
  1.8
  1.8.0.222
  openjdk64-1.8.0.222

Java switching

--You can switch to any version output by jenv versions.

global

$ jenv global 1.8.0.222
$ jenv versions
  system
  1.8
* 1.8.0.222 (set by /Users/[User name]/.jenv/version)
  openjdk64-1.8.0.222
$ java -version
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.222-b10, mixed mode)

local

--Applies only to specific directories. --A .java-version file will be created in the directory where you executed the command, and the specified version of the JDK will be available.

$ jenv local 11.0
$ jenv versions                                                                                           ✘ 
  system
  1.8
  1.8.0.222
* 11.0 (set by /Users/[Directory where jenv local was executed]/.java-version)
  11.0.2
  openjdk64-1.8.0.222
  openjdk64-11.0.2
$ java -version
openjdk version "11.0.2" 2019-01-15
OpenJDK Runtime Environment 18.9 (build 11.0.2+9)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.2+9, mixed mode)
$ cat .java-version
11.0

Automatic setting of environment variable JAVA_HOME

--To set JAVA_HOME automatically, execute ʻenable-plugin export. --Execute disable-plugin export` to cancel the automatic setting.

$ jenv enable-plugin export