Java developer setup for learning and experiments

2 min readApr 12, 2021

Working with multiple Java versions

As of now, there are still applications that work only with JDK 8. There are other applications that work with JDK 11 max. There are few which work on latest & greatest Java 16. Having a local setup to easily switch between them will be very handy.

The following steps are indented for Linux & Mac. I haven’t tried this on Windows for this problem.

jEnv

jEnv — is an amazing command line tool that can help us.

$ git clone https://github.com/jenv/jenv.git ~/.jenvor$ brew install jenv

To activate jenv, add the following to your ~/.zshrc:

export PATH="$HOME/.jenv/bin:$PATH"
eval "$(jenv init -)"

Installing Java

jEnv doesn’t support installation from it’s command line tool. We need to install manually different versions of Java we need.

Option 1: direct install from java website or if it’s mac, brew install.

For Mac with M1 chip, it was easier to go with brew since it takes care of system architecture (M1 chip ARM 64 bit) automatically

# Install OpenJDK
brew install openjdk@11

Option 2: use adoptopenjdk to find installables for different system architecture & java versions.

Add Java to Jenv

# Brew installed path example
$ jenv add /opt/homebrew/opt/openjdk@11# Manually installed path example
$ jenv add /Library/Java/JavaVirtualMachines/temurin-11.jdk/Contents/Home

This will add JDK to one of the options. We can see list of jdk installed :

$jenv versions
  system
  1.7
  1.7.0.80
  1.8
  1.8.0.202
  11
  11.0
  11.0.10
* 15 (set by /Users/sairam/.jenv/version)
  15.0
  15.0.1
  openjdk64-11.0.10
  oracle64-1.7.0.80
  oracle64-1.8.0.202
  oracle64-15.0.1

Configure for this session alone — we can pick our choice from above text

$jenv local 11

Configure globally using

$ jenv global 11

Download maven dependency with transitive dependencies

`Apache Ivy` is super useful when we need to download a maven dependency and along with it’s transitive dependencies.
Let’s say I want to download in a dockerFile spark-hadoop-cloud jar with it’s transitive dependencies. We don’t have to install maven just for this need. We could use `Apache Ivy`

curl -L -O https://repo1.maven.org/maven2/org/apache/ivy/ivy/2.5.0/ivy-2.5.0.jarjava -jar ivy-2.5.0.jar -dependency org.apache.spark spark-hadoop-cloud_2.13 3.3.0 -retrieve "lib/[artifact]-[revision](-[classifier]).[ext]"