I would like to use ArrayUtils.indexOf(int, int) in my Gradle project. IntelliJ marks ArrayUtils red with error: Cannot resolve symbol 'ArrayUtils'.
I can see that Arrayutils is from org.apache.commons.lang3 package, so I downloaded commons-lang3-3.12.0.jar and placed it in lib folder, added it as a dependency followed this answer.
However. it shows as grey in the project tree,
and I got this error with lang3
Actually, my project does not recognize apache.commons at all:
How can I use ArrayUtils.indexOf(int, int) in my Gradle project?