How do I parse command line arguments in Java?

Question

What is a good way of parsing command line arguments in Java?

Answer 1

I've used JOpt and found it quite handy: http://jopt-simple.sourceforge.net/

The front page also provides a list of about 8 alternative libraries, check them out and pick the one that most suits your needs.

Answer 2

Take a look at the Commons CLI project, lots of good stuff in there.

Answer 3

airline @ Github looks good. It is based on annotation and is trying to emulate Git command line structures.

Answer 4

As one of the comments mentioned earlier (https://github.com/pcj/google-options) would be a good choice to start with.

One thing I want to add-on is:

1) If you run into some parser reflection error, please try use a newer version of the guava. in my case:

maven_jar(
    name = "com_google_guava_guava",
    artifact = "com.google.guava:guava:19.0",
    server = "maven2_server",
)

maven_jar(
    name = "com_github_pcj_google_options",
    artifact = "com.github.pcj:google-options:jar:1.0.0",
    server = "maven2_server",
)

maven_server(
    name = "maven2_server",
    url = "http://central.maven.org/maven2/",
)

2) When running the commandline:

bazel run path/to/your:project -- --var1 something --var2 something -v something

3) When you need the usage help, just type:

bazel run path/to/your:project -- --help

Answer 5

I have been trying to maintain a list of Java CLI parsers.

• Airline
  • Active Fork: https://github.com/rvesse/airline
• argparse4j
• argparser
• args4j
• clajr
• cli-parser
• CmdLn
• Commandline
• DocOpt.java
• dolphin getopt
• DPML CLI (Jakarta Commons CLI2 fork)
• Dr. Matthias Laux
• Jakarta Commons CLI
• jargo
• jargp
• jargs
• java-getopt
• jbock
• JCLAP
• jcmdline
• jcommander
• jcommando
• jewelcli (written by me)
• JOpt simple
• jsap
• naturalcli
• Object Mentor CLI article (more about refactoring and TDD)
• parse-cmd
• ritopt
• Rop
• TE-Code Command
• picocli has ANSI colorized usage help and autocomplete

Answer 6

Argparse4j is best I have found. It mimics Python's argparse libary which is very convenient and powerful.