Class CommandLine.Help

java.lang.Object
org.apache.logging.log4j.core.tools.picocli.CommandLine.Help
Enclosing class:
CommandLine

public static class CommandLine.Help extends Object
A collection of methods and inner classes that provide fine-grained control over the contents and layout of the usage help message to display to end users when help is requested or invalid input values were specified.

Layered API

The CommandLine.Command annotation provides the easiest way to customize usage help messages. See the Manual for details.

This Help class provides high-level functions to create sections of the usage help message and headings for these sections. Instead of calling the CommandLine.usage(PrintStream, CommandLine.Help.ColorScheme) method, application authors may want to create a custom usage help message by reorganizing sections in a different order and/or adding custom sections.

Finally, the Help class contains inner classes and interfaces that can be used to create custom help messages.

IOptionRenderer and IParameterRenderer

Renders a field annotated with CommandLine.Option or CommandLine.Parameters to an array of CommandLine.Help.Ansi.Text values. By default, these values are

  • mandatory marker character (if the option/parameter is required)
  • short option name (empty for parameters)
  • comma or empty (empty for parameters)
  • long option names (the parameter label for parameters)
  • description

Other components rely on this ordering.

Layout

Delegates to the renderers to create CommandLine.Help.Ansi.Text values for the annotated fields, and uses a CommandLine.Help.TextTable to display these values in tabular format. Layout is responsible for deciding which values to display where in the table. By default, Layout shows one option or parameter per table row.

TextTable

Responsible for spacing out CommandLine.Help.Ansi.Text values according to the CommandLine.Help.Column definitions the table was created with. Columns have a width, indentation, and an overflow policy that decides what to do if a value is longer than the column's width.

Text

Encapsulates rich text with styles and colors in a way that other components like CommandLine.Help.TextTable are unaware of the embedded ANSI escape codes.

  • Field Details

    • DEFAULT_COMMAND_NAME

      protected static final String DEFAULT_COMMAND_NAME
      Constant String holding the default program name: "<main class>"
      See Also:
    • DEFAULT_SEPARATOR

      protected static final String DEFAULT_SEPARATOR
      Constant String holding the default string that separates options from option parameters: "="
      See Also:
    • usageHelpWidth

      private static final int usageHelpWidth
      See Also:
    • optionsColumnWidth

      private static final int optionsColumnWidth
      See Also:
    • command

      private final Object command
    • commands

      private final Map<String,CommandLine.Help> commands
    • colorScheme

      final CommandLine.Help.ColorScheme colorScheme
    • optionFields

      public final List<Field> optionFields
      Immutable list of fields annotated with CommandLine.Option, in declaration order.
    • positionalParametersFields

      public final List<Field> positionalParametersFields
      Immutable list of fields annotated with CommandLine.Parameters, or an empty list if no such field exists.
    • separator

      public String separator
      The String to use as the separator between options and option parameters. "=" by default, initialized from CommandLine.Command.separator() if defined.
      See Also:
    • commandName

      public String commandName
      The String to use as the program name in the synopsis line of the help message. DEFAULT_COMMAND_NAME by default, initialized from CommandLine.Command.name() if defined.
    • description

      public String[] description
      Optional text lines to use as the description of the help message, displayed between the synopsis and the options list. Initialized from CommandLine.Command.description() if the Command annotation is present, otherwise this is an empty array and the help message has no description. Applications may programmatically set this field to create a custom help message.
    • customSynopsis

      public String[] customSynopsis
      Optional custom synopsis lines to use instead of the auto-generated synopsis. Initialized from CommandLine.Command.customSynopsis() if the Command annotation is present, otherwise this is an empty array and the synopsis is generated. Applications may programmatically set this field to create a custom help message.
    • parameterLabelRenderer

      public CommandLine.Help.IParamLabelRenderer parameterLabelRenderer
      Option and positional parameter value label renderer used for the synopsis line(s) and the option list. By default initialized to the result of createDefaultParamLabelRenderer(), which takes a snapshot of the separator at construction time. If the separator is modified after Help construction, you may need to re-initialize this field by calling createDefaultParamLabelRenderer() again.
    • abbreviateSynopsis

      public Boolean abbreviateSynopsis
      If true, the synopsis line(s) will show an abbreviated synopsis without detailed option names.
    • sortOptions

      public Boolean sortOptions
      If true, the options list is sorted alphabetically.
    • showDefaultValues

      public Boolean showDefaultValues
      If true, the options list will show default values for all options except booleans.
    • requiredOptionMarker

      public Character requiredOptionMarker
      Character used to prefix required options in the options list.
    • headerHeading

      public String headerHeading
      Optional heading preceding the header section. Initialized from CommandLine.Command.headerHeading(), or null.
    • synopsisHeading

      public String synopsisHeading
      Optional heading preceding the synopsis. Initialized from CommandLine.Command.synopsisHeading(), "Usage: " by default.
    • descriptionHeading

      public String descriptionHeading
      Optional heading preceding the description section. Initialized from CommandLine.Command.descriptionHeading(), or null.
    • parameterListHeading

      public String parameterListHeading
      Optional heading preceding the parameter list. Initialized from CommandLine.Command.parameterListHeading(), or null.
    • optionListHeading

      public String optionListHeading
      Optional heading preceding the options list. Initialized from CommandLine.Command.optionListHeading(), or null.
    • commandListHeading

      public String commandListHeading
      Optional heading preceding the subcommand list. Initialized from CommandLine.Command.commandListHeading(). "Commands:%n" by default.
    • footerHeading

      public String footerHeading
      Optional heading preceding the footer section. Initialized from CommandLine.Command.footerHeading(), or null.
  • Constructor Details

    • Help

      public Help(Object command)
      Constructs a new Help instance with a default color scheme, initialized from annotatations on the specified class and superclasses.
      Parameters:
      command - the annotated object to create usage help for
    • Help

      public Help(Object command, CommandLine.Help.Ansi ansi)
      Constructs a new Help instance with a default color scheme, initialized from annotatations on the specified class and superclasses.
      Parameters:
      command - the annotated object to create usage help for
      ansi - whether to emit ANSI escape codes or not
    • Help

      public Help(Object command, CommandLine.Help.ColorScheme colorScheme)
      Constructs a new Help instance with the specified color scheme, initialized from annotatations on the specified class and superclasses.
      Parameters:
      command - the annotated object to create usage help for
      colorScheme - the color scheme to use
  • Method Details

    • addAllSubcommands

      public CommandLine.Help addAllSubcommands(Map<String,CommandLine> commands)
      Registers all specified subcommands with this Help.
      Parameters:
      commands - maps the command names to the associated CommandLine object
      Returns:
      this Help instance (for method chaining)
      See Also:
    • addSubcommand

      public CommandLine.Help addSubcommand(String commandName, Object command)
      Registers the specified subcommand with this Help.
      Parameters:
      commandName - the name of the subcommand to display in the usage message
      command - the annotated object to get more information from
      Returns:
      this Help instance (for method chaining)
    • synopsis

      @Deprecated public String synopsis()
      Deprecated.
      use synopsis(int) instead
      Returns a synopsis for the command without reserving space for the synopsis heading.
      Returns:
      a synopsis
      See Also:
    • synopsis

      public String synopsis(int synopsisHeadingLength)
      Returns a synopsis for the command, reserving the specified space for the synopsis heading.
      Parameters:
      synopsisHeadingLength - the length of the synopsis heading that will be displayed on the same line
      Returns:
      a synopsis
      See Also:
    • abbreviatedSynopsis

      public String abbreviatedSynopsis()
      Generates a generic synopsis like <command name> [OPTIONS] [PARAM1 [PARAM2]...], omitting parts that don't apply to the command (e.g., does not show [OPTIONS] if the command has no options).
      Returns:
      a generic synopsis
    • detailedSynopsis

      @Deprecated public String detailedSynopsis(Comparator<Field> optionSort, boolean clusterBooleanOptions)
      Generates a detailed synopsis message showing all options and parameters. Follows the unix convention of showing optional options and parameters in square brackets ([ ]).
      Parameters:
      optionSort - comparator to sort options or null if options should not be sorted
      clusterBooleanOptions - true if boolean short options should be clustered into a single string
      Returns:
      a detailed synopsis
    • detailedSynopsis

      public String detailedSynopsis(int synopsisHeadingLength, Comparator<Field> optionSort, boolean clusterBooleanOptions)
      Generates a detailed synopsis message showing all options and parameters. Follows the unix convention of showing optional options and parameters in square brackets ([ ]).
      Parameters:
      synopsisHeadingLength - the length of the synopsis heading that will be displayed on the same line
      optionSort - comparator to sort options or null if options should not be sorted
      clusterBooleanOptions - true if boolean short options should be clustered into a single string
      Returns:
      a detailed synopsis
    • appendOptionSynopsis

      private CommandLine.Help.Ansi.Text appendOptionSynopsis(CommandLine.Help.Ansi.Text optionText, Field field, String optionName, String prefix, String suffix)
    • synopsisHeadingLength

      public int synopsisHeadingLength()
      Returns the number of characters the synopsis heading will take on the same line as the synopsis.
      Returns:
      the number of characters the synopsis heading will take on the same line as the synopsis.
      See Also:
    • optionList

      public String optionList()

      Returns a description of the options supported by the application. This implementation sorts options alphabetically, and shows only the non-hidden options in a tabular format using the default renderer and default layout.

      Returns:
      the fully formatted option list
      See Also:
    • optionList

      public String optionList(CommandLine.Help.Layout layout, Comparator<Field> optionSort, CommandLine.Help.IParamLabelRenderer valueLabelRenderer)
      Sorts all Options with the specified comparator (if the comparator is non-null), then adds all non-hidden options to the specified TextTable and returns the result of TextTable.toString().
      Parameters:
      layout - responsible for rendering the option list
      optionSort - determines in what order Options should be listed. Declared order if null
      valueLabelRenderer - used for options with a parameter
      Returns:
      the fully formatted option list
    • parameterList

      public String parameterList()
      Returns the section of the usage help message that lists the parameters with their descriptions.
      Returns:
      the section of the usage help message that lists the parameters
    • parameterList

      public String parameterList(CommandLine.Help.Layout layout, CommandLine.Help.IParamLabelRenderer paramLabelRenderer)
      Returns the section of the usage help message that lists the parameters with their descriptions.
      Parameters:
      layout - the layout to use
      paramLabelRenderer - for rendering parameter names
      Returns:
      the section of the usage help message that lists the parameters
    • heading

      private static String heading(CommandLine.Help.Ansi ansi, String values, Object... params)
    • spaces

      private static char[] spaces(int length)
    • countTrailingSpaces

      private static int countTrailingSpaces(String str)
    • join

      public static StringBuilder join(CommandLine.Help.Ansi ansi, String[] values, StringBuilder sb, Object... params)
      Formats each of the specified values and appends it to the specified StringBuilder.
      Parameters:
      ansi - whether the result should contain ANSI escape codes or not
      values - the values to format and append to the StringBuilder
      sb - the StringBuilder to collect the formatted strings
      params - the parameters to pass to the format method when formatting each value
      Returns:
      the specified StringBuilder
    • format

      private static String format(String formatString, Object... params)
    • customSynopsis

      public String customSynopsis(Object... params)
      Returns command custom synopsis as a string. A custom synopsis can be zero or more lines, and can be specified declaratively with the CommandLine.Command.customSynopsis() annotation attribute or programmatically by setting the Help instance's customSynopsis field.
      Parameters:
      params - Arguments referenced by the format specifiers in the synopsis strings
      Returns:
      the custom synopsis lines combined into a single String (which may be empty)
    • description

      public String description(Object... params)
      Returns command description text as a string. Description text can be zero or more lines, and can be specified declaratively with the CommandLine.Command.description() annotation attribute or programmatically by setting the Help instance's description field.
      Parameters:
      params - Arguments referenced by the format specifiers in the description strings
      Returns:
      the description lines combined into a single String (which may be empty)
    • header

      public String header(Object... params)
      Returns the command header text as a string. Header text can be zero or more lines, and can be specified declaratively with the CommandLine.Command.header() annotation attribute or programmatically by setting the Help instance's header field.
      Parameters:
      params - Arguments referenced by the format specifiers in the header strings
      Returns:
      the header lines combined into a single String (which may be empty)
    • footer

      public String footer(Object... params)
      Returns command footer text as a string. Footer text can be zero or more lines, and can be specified declaratively with the CommandLine.Command.footer() annotation attribute or programmatically by setting the Help instance's footer field.
      Parameters:
      params - Arguments referenced by the format specifiers in the footer strings
      Returns:
      the footer lines combined into a single String (which may be empty)
    • headerHeading

      public String headerHeading(Object... params)
      Returns the text displayed before the header text; the result of String.format(headerHeading, params).
      Parameters:
      params - the parameters to use to format the header heading
      Returns:
      the formatted header heading
    • synopsisHeading

      public String synopsisHeading(Object... params)
      Returns the text displayed before the synopsis text; the result of String.format(synopsisHeading, params).
      Parameters:
      params - the parameters to use to format the synopsis heading
      Returns:
      the formatted synopsis heading
    • descriptionHeading

      public String descriptionHeading(Object... params)
      Returns the text displayed before the description text; an empty string if there is no description, otherwise the result of String.format(descriptionHeading, params).
      Parameters:
      params - the parameters to use to format the description heading
      Returns:
      the formatted description heading
    • parameterListHeading

      public String parameterListHeading(Object... params)
      Returns the text displayed before the positional parameter list; an empty string if there are no positional parameters, otherwise the result of String.format(parameterListHeading, params).
      Parameters:
      params - the parameters to use to format the parameter list heading
      Returns:
      the formatted parameter list heading
    • optionListHeading

      public String optionListHeading(Object... params)
      Returns the text displayed before the option list; an empty string if there are no options, otherwise the result of String.format(optionListHeading, params).
      Parameters:
      params - the parameters to use to format the option list heading
      Returns:
      the formatted option list heading
    • commandListHeading

      public String commandListHeading(Object... params)
      Returns the text displayed before the command list; an empty string if there are no commands, otherwise the result of String.format(commandListHeading, params).
      Parameters:
      params - the parameters to use to format the command list heading
      Returns:
      the formatted command list heading
    • footerHeading

      public String footerHeading(Object... params)
      Returns the text displayed before the footer text; the result of String.format(footerHeading, params).
      Parameters:
      params - the parameters to use to format the footer heading
      Returns:
      the formatted footer heading
    • commandList

      public String commandList()
      Returns a 2-column list with command names and the first line of their header or (if absent) description.
      Returns:
      a usage help section describing the added commands
    • maxLength

      private static int maxLength(Collection<String> any)
    • join

      private static String join(String[] names, int offset, int length, String separator)
    • stringOf

      private static String stringOf(char chr, int length)
    • createDefaultLayout

      public CommandLine.Help.Layout createDefaultLayout()
      Returns a Layout instance configured with the user preferences captured in this Help instance.
      Returns:
      a Layout
    • createDefaultOptionRenderer

      public CommandLine.Help.IOptionRenderer createDefaultOptionRenderer()
      Returns a new default OptionRenderer which converts Options to five columns of text to match the default TextTable column layout. The first row of values looks like this:
      1. the required option marker
      2. 2-character short option name (or empty string if no short option exists)
      3. comma separator (only if both short option and long option exist, empty string otherwise)
      4. comma-separated string with long option name(s)
      5. first element of the CommandLine.Option.description() array

      Following this, there will be one row for each of the remaining elements of the CommandLine.Option.description() array, and these rows look like {"", "", "", "", option.description()[i]}.

      If configured, this option renderer adds an additional row to display the default field value.

      Returns:
      a new default OptionRenderer
    • createMinimalOptionRenderer

      public static CommandLine.Help.IOptionRenderer createMinimalOptionRenderer()
      Returns a new minimal OptionRenderer which converts Options to a single row with two columns of text: an option name and a description. If multiple names or descriptions exist, the first value is used.
      Returns:
      a new minimal OptionRenderer
    • createDefaultParameterRenderer

      public CommandLine.Help.IParameterRenderer createDefaultParameterRenderer()
      Returns a new default ParameterRenderer which converts Parameters to four columns of text to match the default TextTable column layout. The first row of values looks like this:
      1. empty string
      2. empty string
      3. parameter(s) label as rendered by the CommandLine.Help.IParamLabelRenderer
      4. first element of the CommandLine.Parameters.description() array

      Following this, there will be one row for each of the remaining elements of the CommandLine.Parameters.description() array, and these rows look like {"", "", "", param.description()[i]}.

      If configured, this parameter renderer adds an additional row to display the default field value.

      Returns:
      a new default ParameterRenderer
    • createMinimalParameterRenderer

      public static CommandLine.Help.IParameterRenderer createMinimalParameterRenderer()
      Returns a new minimal ParameterRenderer which converts Parameters to a single row with two columns of text: an option name and a description. If multiple descriptions exist, the first value is used.
      Returns:
      a new minimal ParameterRenderer
    • createMinimalParamLabelRenderer

      public static CommandLine.Help.IParamLabelRenderer createMinimalParamLabelRenderer()
      Returns a value renderer that returns the paramLabel if defined or the field name otherwise.
      Returns:
      a new minimal ParamLabelRenderer
    • createDefaultParamLabelRenderer

      public CommandLine.Help.IParamLabelRenderer createDefaultParamLabelRenderer()
      Returns a new default value renderer that separates option parameters from their options with the specified separator string, surrounds optional parameters with '[' and ']' characters and uses ellipses ("...") to indicate that any number of a parameter are allowed.
      Returns:
      a new default ParamLabelRenderer
    • createShortOptionNameComparator

      public static Comparator<Field> createShortOptionNameComparator()
      Sorts Fields annotated with Option by their option name in case-insensitive alphabetic order. If an Option has multiple names, the shortest name is used for the sorting. Help options follow non-help options.
      Returns:
      a comparator that sorts fields by their option name in case-insensitive alphabetic order
    • createShortOptionArityAndNameComparator

      public static Comparator<Field> createShortOptionArityAndNameComparator()
      Sorts Fields annotated with Option by their option max arity first, by min arity next, and by option name last.
      Returns:
      a comparator that sorts fields by arity first, then their option name
    • shortestFirst

      public static Comparator<String> shortestFirst()
      Sorts short strings before longer strings.
      Returns:
      a comparators that sorts short strings before longer strings
    • ansi

      public CommandLine.Help.Ansi ansi()
      Returns whether ANSI escape codes are enabled or not.
      Returns:
      whether ANSI escape codes are enabled or not
    • defaultColorScheme

      public static CommandLine.Help.ColorScheme defaultColorScheme(CommandLine.Help.Ansi ansi)
      Creates and returns a new CommandLine.Help.ColorScheme initialized with picocli default values: commands are bold, options and parameters use a yellow foreground, and option parameters use italic.
      Parameters:
      ansi - whether the usage help message should contain ANSI escape codes or not
      Returns:
      a new default color scheme