joptsimple

Class OptionParser

java.lang.Object

joptsimple.OptionParser

public class OptionParser
extends java.lang.Object

Parses command line arguments, using a syntax that attempts to take from the best of POSIX getopt() and GNU getopt_long().

This parser supports short options and long options.

• Short options begin with a single hyphen ("-") followed by a single letter or digit, or question mark ("?"), or dot (".").
• Short options can accept single arguments. The argument can be made required or optional. The option's argument can occur:
  • in the slot after the option, as in -d /tmp
  • right up against the option, as in -d/tmp
  • right up against the option separated by an equals sign ("="), as in -d=/tmp
  To specify n arguments for an option, specify the option n times, once for each argument, as in -d /tmp -d /var -d /opt; or, when using the "separated values" clause of the "fluent interface" (see below), give multiple values separated by a given character as a single argument to the option.
• Short options can be clustered, so that -abc is treated as -a -b -c, if none of those options can accept arguments.
• An argument consisting only of two hyphens ("--") signals that the remaining arguments are to be treated as non-options.
• An argument consisting only of a single hyphen is considered a non-option argument (though it can be an argument of an option). Many Unix programs treat single hyphens as stand-ins for the standard input or standard output streams.
• Long options begin with two hyphens ("--"), followed by multiple letters, digits, hyphens, question marks, or dots. A hyphen cannot be the first character of a long option specification when configuring the parser.
• You can abbreviate long options, so long as the abbreviation is unique.
• Long options can accept single arguments. The argument can be made required or optional. The option's argument can occur:
  • in the slot after the option, as in --directory /tmp
  • right up against the option separated by an equals sign ("="), as in --directory=/tmp
  Specify multiple arguments for a long option in the same manner as for short options (see above).
• You can use a single hyphen ("-") instead of a double hyphen ("--") for a long option.
• The option -W is reserved. If you tell the parser to recognize alternative long options, then it will treat, for example, -W foo=bar as the long option foo with argument bar, as though you had written --foo=bar.
• You can specify -W as a valid short option, or use it as an abbreviation for a long option, but recognizing alternative long options will always supersede this behavior.
• You can specify a given short or long option multiple times on a single command line. The parser collects any arguments specified for those options as a list.
• If the parser detects an option whose argument is optional, and the next argument "looks like" an option, that argument is not treated as the argument to the option, but as a potentially valid option. If, on the other hand, the optional argument is typed as a derivative of Number, then that argument is treated as the negative number argument of the option, even if the parser recognizes the corresponding numeric option. For example:

  
       OptionParser parser = new OptionParser();
       parser.accepts( "a" ).withOptionalArg().ofType( Integer.class );
       parser.accepts( "2" );
       OptionSet options = parser.parse( "-a", "-2" );
     

  In this case, the option set contains "a" with argument -2, not both "a" and "2". Swapping the elements in the args array gives the latter.

There are two ways to tell the parser what options to recognize:

1. A "fluent interface"-style API for specifying options, available since version 2. Sentences in this fluent interface language begin with a call to accepts or acceptsAll methods; calls on the ensuing chain of objects describe whether the options can take an argument, whether the argument is required or optional, to what type arguments of the options should be converted if any, etc. Since version 3, these calls return an instance of OptionSpec, which can subsequently be used to retrieve the arguments of the associated option in a type-safe manner.
2. Since version 1, a more concise way of specifying short options has been to use the special constructor. Arguments of options specified in this manner will be of type String. Here are the rules for the format of the specification strings this constructor accepts:
   • Any letter or digit is treated as an option character.
   • If an option character is followed by a single colon (":"), then the option requires an argument.
   • If an option character is followed by two colons ("::"), then the option accepts an optional argument.
   • Otherwise, the option character accepts no argument.
   • If the option specification string begins with a plus sign ("+"), the parser will behave "POSIX-ly correct".
   • If the option specification string contains the sequence "W;" (capital W followed by a semicolon), the parser will recognize the alternative form of long options.

Each of the options in a list of options given to acceptsAll is treated as a synonym of the others. For example:

     
     OptionParser parser = new OptionParser();
     parser.acceptsAll( asList( "w", "interactive", "confirmation" ) );
     OptionSet options = parser.parse( "-w" );
     
   

In this case, options.has would answer true when given arguments "w", "interactive", and "confirmation". The OptionSet would give the same responses to these arguments for its other methods as well.

By default, as with GNU getopt(), the parser allows intermixing of options and non-options. If, however, the parser has been created to be "POSIX-ly correct", then the first argument that does not look lexically like an option, and is not a required argument of a preceding option, signals the end of options. You can still bind optional arguments to their options using the abutting (for short options) or = syntax.

Unlike GNU getopt(), this parser does not honor the environment variable POSIXLY_CORRECT. "POSIX-ly correct" parsers are configured by either:

1. using the method posixlyCorrect(boolean), or
2. using the constructor with an argument whose first character is a plus sign ("+")

See Also:

The GNU C Library

Constructor Summary

Constructors

Constructor and Description
OptionParser() Creates an option parser that initially recognizes no options, and does not exhibit "POSIX-ly correct" behavior.
OptionParser(java.lang.String optionSpecification) Creates an option parser and configures it to recognize the short options specified in the given string.

Method Summary

Modifier and Type	Method and Description
OptionSpecBuilder	accepts(java.lang.String option) Tells the parser to recognize the given option.
OptionSpecBuilder	accepts(java.lang.String option, java.lang.String description) Tells the parser to recognize the given option.
OptionSpecBuilder	acceptsAll(java.util.Collection<java.lang.String> options) Tells the parser to recognize the given options, and treat them as synonymous.
OptionSpecBuilder	acceptsAll(java.util.Collection<java.lang.String> options, java.lang.String description) Tells the parser to recognize the given options, and treat them as synonymous.
OptionSet	parse(java.lang.String... arguments) Parses the given command line arguments according to the option specifications given to the parser.
void	posixlyCorrect(boolean setting) Tells the parser whether or not to behave "POSIX-ly correct"-ly.
void	printHelpOn(java.io.OutputStream sink) Writes information about the options this parser recognizes to the given output sink.
void	printHelpOn(java.io.Writer sink) Writes information about the options this parser recognizes to the given output sink.
void	recognizeAlternativeLongOptions(boolean recognize) Tells the parser either to recognize or ignore "-W"-style long options.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OptionParser

public OptionParser()

Creates an option parser that initially recognizes no options, and does not exhibit "POSIX-ly correct" behavior.

OptionParser

public OptionParser(java.lang.String optionSpecification)

Creates an option parser and configures it to recognize the short options specified in the given string.

Arguments of options specified this way will be of type String.

Parameters:

optionSpecification - an option specification

Throws:

java.lang.NullPointerException - if optionSpecification is null

OptionException - if the option specification contains illegal characters or otherwise cannot be recognized

Method Detail

accepts

public OptionSpecBuilder accepts(java.lang.String option)

Tells the parser to recognize the given option.

This method returns an instance of OptionSpecBuilder to allow the formation of parser directives as sentences in a fluent interface language. For example:

   OptionParser parser = new OptionParser();
   parser.accepts( "c" ).withRequiredArg().ofType( Integer.class );
 

If no methods are invoked on the returned OptionSpecBuilder, then the parser treats the option as accepting no argument.

Parameters:

option - the option to recognize

Returns:

an object that can be used to flesh out more detail about the option

Throws:

OptionException - if the option contains illegal characters

java.lang.NullPointerException - if the option is null

accepts

public OptionSpecBuilder accepts(java.lang.String option,
                                 java.lang.String description)

Tells the parser to recognize the given option.

Parameters:

option - the option to recognize

description - a string that describes the purpose of the option. This is used when generating help information about the parser.

Returns:

an object that can be used to flesh out more detail about the option

Throws:

OptionException - if the option contains illegal characters

java.lang.NullPointerException - if the option is null

See Also:

accepts(String)

acceptsAll

public OptionSpecBuilder acceptsAll(java.util.Collection<java.lang.String> options)

Tells the parser to recognize the given options, and treat them as synonymous.

Parameters:

options - the options to recognize and treat as synonymous

Returns:

an object that can be used to flesh out more detail about the options

Throws:

OptionException - if any of the options contain illegal characters

java.lang.NullPointerException - if the option list or any of its elements are null

See Also:

accepts(String)

acceptsAll

public OptionSpecBuilder acceptsAll(java.util.Collection<java.lang.String> options,
                                    java.lang.String description)

Tells the parser to recognize the given options, and treat them as synonymous.

Parameters:

options - the options to recognize and treat as synonymous

description - a string that describes the purpose of the option. This is used when generating help information about the parser.

Returns:

an object that can be used to flesh out more detail about the options

Throws:

OptionException - if any of the options contain illegal characters

java.lang.NullPointerException - if the option list or any of its elements are null

java.lang.IllegalArgumentException - if the option list is empty

See Also:

acceptsAll(Collection)

posixlyCorrect

public void posixlyCorrect(boolean setting)

Tells the parser whether or not to behave "POSIX-ly correct"-ly.

Parameters:

setting - true if the parser should behave "POSIX-ly correct"-ly

recognizeAlternativeLongOptions

public void recognizeAlternativeLongOptions(boolean recognize)

Tells the parser either to recognize or ignore "-W"-style long options.

Parameters:

recognize - true if the parser is to recognize the special style of long options

printHelpOn

public void printHelpOn(java.io.OutputStream sink)
                 throws java.io.IOException

Writes information about the options this parser recognizes to the given output sink.

The output sink is flushed, but not closed.

Parameters:

sink - the sink to write information to

Throws:

java.io.IOException - if there is a problem writing to the sink

java.lang.NullPointerException - if sink is null

See Also:

printHelpOn(Writer)

printHelpOn

public void printHelpOn(java.io.Writer sink)
                 throws java.io.IOException

Writes information about the options this parser recognizes to the given output sink.

The output sink is flushed, but not closed.

Parameters:

sink - the sink to write information to

Throws:

java.io.IOException - if there is a problem writing to the sink

java.lang.NullPointerException - if sink is null

See Also:

printHelpOn(OutputStream)

parse

public OptionSet parse(java.lang.String... arguments)

Parses the given command line arguments according to the option specifications given to the parser.

Parameters:

arguments - arguments to parse

Returns:

an OptionSet describing the parsed options, their arguments, and any non-option arguments found

Throws:

OptionException - if problems are detected while parsing

java.lang.NullPointerException - if the argument list is null