Here are some of the most popular. They are all pretty feature complete, and having used the top two I can recommend them.
-
Commons CLI
http://commons.apache.org/cli/ -
Java Gems
http://code.google.com/p/javagems/ -
picocli (with colorized usage help and autocomplete)
http://picocli.info/ -
GetOpt
http://www.urbanophile.com/arenn/hacking/download.html
EDIT: For completeness, here are some others I’ve come across
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JOpt Simple
http://jopt-simple.sourceforge.net/ -
Args4J
https://args4j.dev.java.net/ -
ArgParser
http://people.cs.ubc.ca/~lloyd/java/argparser.html -
Natural CLI
http://naturalcli.sourceforge.net/ -
TE-Code
http://te-code.sourceforge.net/ -
JewelCli
http://jewelcli.sourceforge.net/ -
JCommando
http://jcommando.sourceforge.net/ -
Parse-cmd
http://code.google.com/p/parse-cmd/