Installing different versions of open jdk through Homebrew(assuming already installed) and already having Java 8.
We need to install a tool called jenv - Java version manager which is similar to nvm(nodeJs version manager).
brew install jenv
Export the jenv path to .bash_profile or .zshrc - whatever you are using. I am using .zshrc
echo 'export PATH="$HOME/.jenv/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(jenv init -)"' >> ~/.zshrc
After executing above command make sure you are having the below in ~/.zshrc
export PATH="$HOME/.jenv/bin:$PATH"
eval "$(jenv init -)"
Then update the terminal using
source ~/.zshrc
Check the jenv health
jenv doctor
It will return something similar to this
[OK] No JAVA_HOME set
[ERROR] Java binary in path is not in the jenv shims.
[ERROR] Please check your path, or try using /path/to/java/home is not a valid path to java installation.
PATH : /usr/local/Cellar/jenv/0.5.2/libexec/libexec:/Users/gramcha/.jenv/shims:/Users/gramcha/.jenv/shims:/Users/gramcha/.jenv/bin:/Users/gramcha/.jenv/bin:/Users/gramcha/chromedriver:/opt/local/bin:/opt/local/sbin:/Users/gramcha/.jenv/shims:/Users/gramcha/.jenv/bin:/Users/gramcha/.jenv/bin:/Users/gramcha/chromedriver:/opt/local/bin:/opt/local/sbin:/Users/gramcha/.jenv/shims:/Users/gramcha/.jenv/bin:/Users/gramcha/.jenv/shims:/Users/gramcha/.jenv/bin:/Users/gramcha/chromedriver:/opt/local/bin:/opt/local/sbin:/Users/gramcha/.nvm/versions/node/v10.17.0/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
[OK] Jenv is correctly loaded
No need to worry about error message as long as Jenv is correctly loaded is printed.
To ensure that JAVA_HOME is correct
jenv enable-plugin export
Assuming Maven is used and to educate maven about Java version used
jenv enable-plugin maven
Intalling latest open jdk version(15) at the time of writing this script
brew install openjdk
It will printout
Updating Homebrew...
==> Downloading https://homebrew.bintray.com/bottles/openjdk-15.0.1.mojave.bottle.tar.gz
==> Downloading from https://d29vzk4ow07wi7.cloudfront.net/a4f00dc8b4c69bff53828f32c82b0a6be41b23a69a7775a95cdbc9e01d9bdb68?response-content-disposition=attachment%3Bfilename%3D%22openjdk-15.0.1.mojave.bottle.tar.gz%22&Policy=eyJTdGF0ZW
######################################################################## 100.0%
==> Pouring openjdk-15.0.1.mojave.bottle.tar.gz
==> Caveats
For the system Java wrappers to find this JDK, symlink it with
sudo ln -sfn /usr/local/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk
openjdk is keg-only, which means it was not symlinked into /usr/local,
because it shadows the macOS `java` wrapper.
If you need to have openjdk first in your PATH run:
echo 'export PATH="/usr/local/opt/openjdk/bin:$PATH"' >> ~/.zshrc
For compilers to find openjdk you may need to set:
export CPPFLAGS="-I/usr/local/opt/openjdk/include"
==> Summary
🍺 /usr/local/Cellar/openjdk/15.0.1: 614 files, 323.8MB
Execute the caveats suggested by above install
sudo ln -sfn /usr/local/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk
echo 'export PATH="/usr/local/opt/openjdk/bin:$PATH"' >> ~/.zshrc
export CPPFLAGS="-I/usr/local/opt/openjdk/include"
similarly if you want to install java8 execute below and follow the caveats.
brew install openjdk@8
I already having AdoptOpenJDK 8 in my machine. In case if you want to install that
brew install AdoptOpenJDK/openjdk/adoptopenjdk{8,11}
Execute below command to see available JVM's in machine
/usr/libexec/java_home -V
It will print something like this
Matching Java Virtual Machines (2):
15.0.1, x86_64: "OpenJDK 15.0.1" /Library/Java/JavaVirtualMachines/openjdk.jdk/Contents/Home
1.8.0_212, x86_64: "AdoptOpenJDK 8" /Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home
/Library/Java/JavaVirtualMachines/openjdk.jdk/Contents/Home
Add java 15 and java 8 paths to jenv by copying path from above previous command output.
jenv add /Library/Java/JavaVirtualMachines/openjdk.jdk/Contents/Home
jenv add /Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home
It will print the below outputs respectively.
openjdk64-15.0.1 added
15.0.1 added
15.0 added
openjdk64-1.8.0.212 added
1.8.0.212 added
1.8 added
Check the jenv for available versions
jenv versions
It will print below outputs
* system (set by /Users/gramcha/.jenv/version)
1.8
1.8.0.212
15.0
15.0.1
openjdk64-1.8.0.212
openjdk64-15.0.1
Set system level version
jenv global 15.0
and check the java version
java -version
and it should print 15.0
openjdk version "15.0.1" 2020-10-20
OpenJDK Runtime Environment (build 15.0.1+9)
OpenJDK 64-Bit Server VM (build 15.0.1+9, mixed mode, sharing)
Some of projects wants older version like java8 to support that add project wise version. Go inside the specific project folder and execute below command
jenv local 1.8
This will create the .java-version file that describes which java version to use.
To set the java specific version at teminal level execute that
jenv shell 1.8
Check the jenv versions it should print
system
* 1.8 (set by JENV_VERSION environment variable)
1.8.0.212
15.0
15.0.1
openjdk64-1.8.0.212
openjdk64-15.0.1