Annotation Interface CommandLine.Parameters

Element Details

• index

  String index

  Specify an index ("0", or "1", etc.) to pick which of the command line arguments should be assigned to this field. For array or Collection fields, you can also specify an index range ("0..3", or "2..*", etc.) to assign a subset of the command line arguments to this field. The default is "*", meaning all command line arguments.

  Returns:

  an index or range specifying which of the command line arguments should be assigned to this field

  Default:

  ""

• description

  String[] description

  Description of the parameter(s), used when generating the usage documentation. Each element of the array is rendered on a separate line.

  May contain embedded format specifiers like %n line separators. Literal percent '%' characters must be escaped with another %.

  The description may contain variables that are rendered when help is requested. The string ${DEFAULT-VALUE} is replaced with the default value of the positional parameter. This is regardless of the command's showDefaultValues setting or the positional parameter's showDefaultValue setting. The string ${COMPLETION-CANDIDATES} is replaced with the completion candidates generated by completionCandidates() in the description for this positional parameter. Also, embedded %n newline markers are converted to actual newlines.

  Returns:

  the description of the parameter(s)

  Default:

  {}

• arity

  String arity

  Specifies the minimum number of required parameters and the maximum number of accepted parameters. If a positive arity is declared, and the user specifies an insufficient number of parameters on the command line, CommandLine.MissingParameterException is thrown by the CommandLine.parse(String...) method.

  The default depends on the type of the parameter: booleans require no parameters, arrays and Collections accept zero to any number of parameters, and any other type accepts one parameter.

  For single-value parameters, setting arity = "0..1" makes a positional parameter optional, while setting arity = "1" makes it required.

  Required parameters that are part of a group are required within the group, not required within the command: the group's multiplicity determines whether the group itself is required or optional.

  Returns:

  the range of minimum and maximum parameters accepted by this command

  Default:

  ""

• paramLabel

  String paramLabel

  Specify a paramLabel for the parameter to be used in the usage help message. If omitted, picocli uses the field name in fish brackets ('<' and '>') by default. Example:

  class Example {
        @Parameters(paramLabel="FILE", description="path of the input FILE(s)")
        private File[] inputFiles;
    }

  By default, the above gives a usage help message like the following:

    Usage: <main class> [FILE...]
    [FILE...]       path of the input FILE(s)
    

  Returns:

  name of the positional parameter used in the usage help message

  Default:

  ""

• hideParamSyntax

  boolean hideParamSyntax

  Returns whether usage syntax decorations around the paramLabel should be suppressed. The default is false: by default, the paramLabel is surrounded with '[' and ']' characters if the value is optional and followed by ellipses ("...") when multiple values can be specified.

  Since:

  3.6.0

  Default:

  false

• type

  Class<?>[] type

  Optionally specify a type to control exactly what Class the positional parameter should be converted to. This may be useful when the field type is an interface or an abstract class. For example, a field can be declared to have type java.lang.Number, and annotating @Parameters(type=Short.class) ensures that the positional parameter value is converted to a Short before setting the field value.

  For array fields whose component type is an interface or abstract class, specify the concrete component type. For example, a field with type Number[] may be annotated with @Parameters(type=Short.class) to ensure that positional parameter values are converted to Short before adding an element to the array.

  Picocli will use the CommandLine.ITypeConverter that is registered for the specified type to convert the raw String values before modifying the field value.

  Prior to 2.0, the type attribute was necessary for Collection and Map fields, but starting from 2.0 picocli will infer the component type from the generic type's type arguments. For example, for a field of type Map<TimeUnit, Long> picocli will know the positional parameter should be split up in key=value pairs, where the key should be converted to a java.util.concurrent.TimeUnit enum value, and the value should be converted to a Long. No @Parameters(type=...) type attribute is required for this. For generic types with wildcards, picocli will take the specified upper or lower bound as the Class to convert to, unless the @Parameters annotation specifies an explicit type attribute.

  If the field type is a raw collection or a raw map, and you want it to contain other values than Strings, or if the generic type's type arguments are interfaces or abstract classes, you may specify a type attribute to control the Class that the positional parameter should be converted to.

  Returns:

  the type(s) to convert the raw String values

  Default:

  {}

• converter

  Class<? extends CommandLine.ITypeConverter<?>>[] converter

  Optionally specify one or more CommandLine.ITypeConverter classes to use to convert the command line argument into a strongly typed value (or key-value pair for map fields). This is useful when a particular field should use a custom conversion that is different from the normal conversion for the field's type.

  For example, for a specific field you may want to use a converter that maps the constant names defined in java.sql.Types to the int value of these constants, but any other int fields should not be affected by this and should continue to use the standard int converter that parses numeric values.

  Returns:

  the type converter(s) to use to convert String values to strongly typed values for this field

  See Also:

  • CommandLine.registerConverter(Class, ITypeConverter)

  Default:

  {}

• split

  String split

  Specify a regular expression to use to split positional parameter values before applying them to the field. All elements resulting from the split are added to the array or Collection. Previously ignored for single-value fields, from picocli 4.0 a split regex can only be specified on multi-value options and positional parameters.

  Returns:

  a regular expression to split operand values or "" if the value should not be split

  See Also:

  • String.split(String)

  Default:

  ""

• hidden

  boolean hidden

  Set hidden=true if this parameter should not be included in the usage message.

  Returns:

  whether this parameter should be excluded from the usage message

  Default:

  false

• defaultValue

  String defaultValue

  Returns the default value of this positional parameter, before splitting and type conversion.

  Returns:

  a String that (after type conversion) will be used as the value for this positional parameter if no value was specified on the command line

  Since:

  3.2

  Default:

  "__no_default_value__"

• showDefaultValue

  CommandLine.Help.Visibility showDefaultValue

  Use this attribute to control for a specific positional parameter whether its default value should be shown in the usage help message. If not specified, the default value is only shown when the CommandLine.Command.showDefaultValues() is set true on the command. Use this attribute to specify whether the default value for this specific positional parameter should always be shown or never be shown, regardless of the command setting.

  Note that picocli 3.2 allows embedding default values anywhere in the description that ignores this setting.

  Returns:

  whether this positional parameter's default value should be shown in the usage help message

  Default:

  ON_DEMAND

• completionCandidates

  Class<? extends Iterable<String>> completionCandidates

  Use this attribute to specify an Iterable<String> class that generates completion candidates for this positional parameter. For map fields, completion candidates should be in key=value form.

  Completion candidates are used in bash completion scripts generated by the picocli.AutoComplete class. Unfortunately, picocli.AutoComplete is not very good yet at generating completions for positional parameters.

  Returns:

  a class whose instances can iterate over the completion candidates for this positional parameter

  Since:

  3.2

  See Also:

  • picocli.CommandLine.IFactory

  Default:

  nz.org.riskscape.picocli.CommandLine.NoCompletionCandidates.class

• interactive

  boolean interactive

  Set interactive=true if this positional parameter will prompt the end user for a value (like a password). Only supported for single-value positional parameters (not arrays, collections or maps). When running on Java 6 or greater, this will use the Console.readPassword() API to get a value without echoing input to the console.

  Returns:

  whether this positional parameter prompts the end user for a value to be entered on the command line

  Since:

  3.5

  Default:

  false

• descriptionKey

  String descriptionKey

  ResourceBundle key for this option. If not specified, (and a ResourceBundle exists for this command) an attempt is made to find the positional parameter description using paramLabel() + "[" + index() + "]" as key.

  Since:

  3.6

  See Also:

  • CommandLine.Model.ArgSpec.description()

  Default:

  ""

• parameterConsumer

  Class<? extends CommandLine.IParameterConsumer> parameterConsumer

  Optionally specify a custom IParameterConsumer to temporarily suspend picocli's parsing logic and process one or more command line arguments in a custom manner.

  Default:

  nz.org.riskscape.picocli.CommandLine.NullParameterConsumer.class