Package picocli

Annotation Type CommandLine.ArgGroup

  • @Retention(RUNTIME)
@Target({FIELD,METHOD,PARAMETER})
public static @interface CommandLine.ArgGroup
    A Command may define one or more ArgGroups: a group of options, positional parameters or a mixture of the two. Groups can be used to:
    • define mutually exclusive arguments. By default, options and positional parameters in a group are mutually exclusive. This can be controlled with the exclusive attribute. Picocli will throw a CommandLine.MutuallyExclusiveArgsException if the command line contains multiple arguments that are mutually exclusive.
    • define a set of arguments that must co-occur. Set exclusive = false to define a group of options and positional parameters that must always be specified together. Picocli will throw a MissingParameterException if not all the options and positional parameters in a co-occurring group are specified together.
    • create an option section in the usage help message. To be shown in the usage help message, a group needs to have a heading (which may come from a resource bundle). Groups without a heading are only used for validation. Set validate = false for groups whose purpose is only to customize the usage help message.
    • define composite repeating argument groups. Groups may contain other groups to create composite groups.

    Groups may be optional (multiplicity = "0..1"), required (multiplicity = "1"), or repeating groups (multiplicity = "0..*" or multiplicity = "1..*"). For a group of mutually exclusive arguments, making the group required means that one of the arguments in the group must appear on the command line, or a MissingParameterException is thrown. For a group of co-occurring arguments, all arguments in the group must appear on the command line.

    Groups can be composed for validation purposes:

    • When the parent group is mutually exclusive, only one of the subgroups may be present.
    • When the parent group is a co-occurring group, all subgroups must be present.
    • When the parent group is required, at least one subgroup must be present.

    Below is an example of an ArgGroup defining a set of dependent options that must occur together. All options are required within the group, while the group itself is optional:

     public class DependentOptions {
     @ArgGroup(exclusive = false, multiplicity = "0..1")
     Dependent group;

     static class Dependent {
         @Option(names = "-a", required = true) int a;
         @Option(names = "-b", required = true) int b;
         @Option(names = "-c", required = true) int c;
     }
 }
    Since:
    4.0
    See Also:
    CommandLine.Model.ArgGroupSpec

    • Optional Element Summary

      Optional Elements 
      Modifier and Type Optional Element Description
      boolean exclusive
      Determines whether this is a mutually exclusive group; true by default.
      String heading
      The heading of this group, used when generating the usage documentation.
      String headingKey
      ResourceBundle key for this group's usage help message section heading.
      String multiplicity
      Determines how often this group can be specified on the command line; "0..1" (optional) by default.
      int order
      Determines the position in the options list in the usage help message at which this group should be shown.
      boolean validate
      Determines whether picocli should validate the rules of this group (true by default).

    • Element Detail

      • heading

        String heading
        The heading of this group, used when generating the usage documentation. When neither a heading nor a headingKey are specified, this group is used for validation only and does not change the usage help message.
        Default:
        "__no_heading__"

      • headingKey

        String headingKey
        ResourceBundle key for this group's usage help message section heading. When neither a heading nor a headingKey are specified, this group is used for validation only and does not change the usage help message.
        Default:
        "__no_heading_key__"

      • exclusive

        boolean exclusive
        Determines whether this is a mutually exclusive group; true by default. If false, this is a co-occurring group. Ignored if validate() is false.
        Default:
        true

      • multiplicity

        String multiplicity
        Determines how often this group can be specified on the command line; "0..1" (optional) by default. For a group of mutually exclusive arguments, making the group required multiplicity = "1" means that one of the arguments in the group must appear on the command line, or a MissingParameterException is thrown. For a group of co-occurring arguments, making the group required means that all arguments in the group must appear on the command line. Ignored if validate() is false.
        Default:
        "0..1"

      • validate

        boolean validate
        Determines whether picocli should validate the rules of this group (true by default). For a mutually exclusive group validation means verifying that no more than one elements of the group is specified on the command line; for a co-ocurring group validation means verifying that all elements of the group are specified on the command line. Set validate = false for groups whose purpose is only to customize the usage help message.
        See Also:
        multiplicity(), heading()
        Default:
        true

      • order

        int order
        Determines the position in the options list in the usage help message at which this group should be shown. Groups with a lower number are shown before groups with a higher number. This attribute is only honored for groups that have a heading (or a headingKey with a non-null resource bundle value).
        Default:
        -1