de.weltraumschaf.commons.jcommander

Class JCommanderImproved<O>

java.lang.Object

de.weltraumschaf.commons.jcommander.JCommanderImproved<O>

Type Parameters:

O - type of options bean

public final class JCommanderImproved<O>
extends Object

This helper class removes boiler plate if you use JCommander.

Example:

 public static void main(final String[] args) {
     // Create an instance for your custom Options type.
     // This option type is a typical JCommander annotated beanclass.
     // Note that this type must provide a zero argument constructor.
     // If not the constructor of JCommanderImproved throws an exception.
     final JCommanderImproved<Options> cliArgs = new JCommanderImproved<Options>("mytool", Options.class);

     // Parse and gather the options.
     final Options opts = cliArgs.gatherOptions(args);

     // Print the helpmessage:
     System.out.print(
         cliArgs.helpMessage(
             "[-v|--version] [-h|--help]",
             "This is mytool.",
             "$> mytool -v")
     );
 }
 
 

Author:

Sven Strittmatter

Field Summary

Fields

Modifier and Type	Field and Description
private static String	DEFAULT_NEW_LINE System dependent newline character.
private com.beust.jcommander.JCommander	optionsParser Parses the command line options.
private Class<O>	optionsType Class for type of options model.
private String	programName The name of the tool for what this class gather options.

Constructor Summary

Constructors

Constructor and Description
JCommanderImproved(String programName, Class<O> optionsType) Dedicated constructor.

Method Summary

Methods

Modifier and Type	Method and Description
private static <O> O	createOptions(Class<O> optionsType) Creates an option bean.
O	gatherOptions(String[] args) Parses the given arguments and return a ready set up options bean.
String	helpMessage(String usage, String descriptions, String example) Generates help message for main command.
(package private) static String	lineBreak(String in, int length, int leftPadLength) Breaks the given string to fit given length and pads on the left side before line breaks.
(package private) static String	rightPad(String in, int length) Pads given string with spaces on the right side to given length.
(package private) static String	spaces(int length) Generates a string of spaces with given length.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_NEW_LINE

private static final String DEFAULT_NEW_LINE

System dependent newline character.

optionsParser

private final com.beust.jcommander.JCommander optionsParser

Parses the command line options.

optionsType

private final Class<O> optionsType

Class for type of options model.

programName

private final String programName

The name of the tool for what this class gather options.

Constructor Detail

JCommanderImproved

public JCommanderImproved(String programName,
                  Class<O> optionsType)

Dedicated constructor.

Throws an IllegalArgumentException if the options type can't be instantiated.

Parameters:

programName - must not be null or empty

optionsType - must not be null

Method Detail

createOptions

private static <O> O createOptions(Class<O> optionsType)

Creates an option bean.

Throws an IllegalArgumentException if the options type can't be instantiated.

Type Parameters:

O - type of options bean

Parameters:

optionsType - must not be null

Returns:

never null, always new instance

gatherOptions

public O gatherOptions(String[] args)

Parses the given arguments and return a ready set up options bean.

Parameters:

args - must not be null

Returns:

never null always new instance

helpMessage

public String helpMessage(String usage,
                 String descriptions,
                 String example)

Generates help message for main command.

The given parameters enhance the produced help messages:

• usage: A usage string like e.g. -a --foo [-h|--help]
• descriptions: A more or less longer description of the tool.
• example: Examples how to use the tool.

If one of the three parameters is empty the whole part is omitted in the output.

Parameters:

usage - must not be null

descriptions - must not be null

example - must not be null

Returns:

never null or empty

rightPad

static String rightPad(String in,
              int length)

Pads given string with spaces on the right side to given length.

Parameters:

in - if null only spaces will be returned

length - must not be negative

Returns:

never null

spaces

static String spaces(int length)

Generates a string of spaces with given length.

Parameters:

length - empty string will be returned if < 1

Returns:

never null

lineBreak

static String lineBreak(String in,
               int length,
               int leftPadLength)

Breaks the given string to fit given length and pads on the left side before line breaks.

Parameters:

in - empty string will be returned if null

length - must not be negative

leftPadLength - must not be negative

Returns:

never null