Setting up jEnv

With OpenJDK, there is a need to have multiple JDK versions installed as there are many releases that are used by different projects. More and more projects are supporting multiple Java versions as well. This problem was not as prevalent in the Java ecosystem but the Ruby ecosystem had it long back. There are multiple tools to manage Ruby versions. The approach of rbenv is probably the simplest. On the same lines, we have jEnv for Java.

To setup jEnv, the steps are simple

1. Install jEnv (brew install jenv)
2. Setup shell profile (~/.bash_profile)
export PATH="$HOME/.jenv/bin:$PATH"
eval "$(jenv init -)"

3. Install Java
4. Set local or shell version of Java (jenv local openjdk64-1.8.0.192)

Jacoco instrumentation error

In a Java project build, I was getting an error complaining about Jacoco failing to instrument a particular class. Looking at the complete stack trace of the error, it was an exception about index going out of bounds.

Caused by: java.lang.ArrayIndexOutOfBoundsException: 6
at org.jacoco.core.internal.BytecodeVersion.get(BytecodeVersion.java:41)
at org.jacoco.core.instr.Instrumenter.instrument(Instrumenter.java:87)
at org.jacoco.core.instr.Instrumenter.instrument(Instrumenter.java:123)
... 25 more
Fortunately, a little bit of search showed that it is related to Java. My initial version of Java was '1.8.0.121'. The fix was backported to '1.8.0.172'. I also had '1.8.0.192' installed. So, I switched versions and tried a clean build. It worked fine.