commandline

Table of Contents

• What is supported
• How to extend
• Examples
  • Primitive calculator

Easy to use, extensible command line parser written in Java with no dependencies. Supports both UNIX and GNU command line options conventions.

What is supported

• positional arguments(obvious one)

• short options

  Value for the option is provided in the next argument or is sticked to the option:
  -t <value> or -t<value>

• long options

  Value for the option is provided in the next argument or is sticked to the option with = separating them:
  --url <value> or --url=<value>

• flags

  flag is an option without a value i.e. -f or --flag

• short flags can stick to each other

  -f -t is the same as -ft or -tf

• help generation

• mutual exclusive groups

  Sometimes there’re options/flags that can’t be used together in one command line. GroupValidator helps with the issue.

How to extend

• argument/option value checker

  If you want make some constraints on the value of an argument, option set checker for it. There’re few available in the Util class.

  For example if option is a choice(i.e. can have only few values) you can use Util.choice() checker.

• help generator

  You can provide your own help generator to CommandLineConfiguration constructor. DefaultHelpGenerator.

• command line validator

  GroupValidator as an example of it.

Examples

Primitive calculator

It gets operation type from the option -o or --operation. There’re four operation types: sum, production, subtraction. Possible values are: sum, prod, sub. Positional arguments are the numbers. Also there’s a flag -v or --verbose for printing the whole expression. The whole example you can find in the file SimpleCalculator.java.

CommandLineConfiguration configuration = new CommandLineConfiguration();
RequiredArgument argument = configuration.addRequiredArgument("numbers")
        .setDescription("Integer number")
        .setChecker(Util.isInteger())
        .addDefaultValue("0");

Option option = configuration.addOption("operation", "-o")
        .addPrefix("--operation")
        .setDescription("Operation type")
        .addDefaultValue("sum")
        .setChecker(Util.choice("sum", "prod", "sub"));

Flag flag = configuration.addFlag("verbose", "-v")
        .addPrefix("--verbose")
        .setDescription("Verbose mode");

CommandLine.parse(configuration, args);

On -h or --help it prints:

Usage: java -cp ${CLASSPATH} ${MAIN_CLASS} [OPTIONS] numbers  [numbers...]

Positional arguments:
  numbers  Integer number (default: 0)

Prefixed arguments:
  Optional:
    --operation, -o  Operation type (default: sum)
    --help, -h       print help information and exit
    --verbose, -v    Verbose mode