Module net.sourceforge.argparse4j
Package net.sourceforge.argparse4j.impl.type

Class ReflectArgumentType<T>

  • All Implemented Interfaces:
    ArgumentType<T>, MetavarInference
    public class ReflectArgumentType<T>
extends java.lang.Object
implements ArgumentType<T>, MetavarInference

    This implementation converts String value into given type using type's valueOf(java.lang.String) static method or its constructor. This class implements MetavarInference interface, and performs special handling when Boolean class is passed to the constructor. In that case, inferMetavar() returns convenient metavar string for Boolean values, and it is used when Argument.metavar(String...) is not used.

    • Field Detail

      • type_

        private final java.lang.Class<T> type_

    • Constructor Detail

      • ReflectArgumentType

        public ReflectArgumentType​(java.lang.Class<T> type)

        Creates ReflectArgumentType object with given type.

        This object first tries to convert given String using valueOf(java.lang.String) static method of given type. If that failed, then use constructor of given type for conversion. valueOf() method and/or constructor must be declared as public. Otherwise, they cannot be invoked. The constructor of type must accept 1 String argument.

        If error occurred inside the valueOf static method or constructor, ArgumentParserException will be thrown. If error occurred in other locations, subclass of RuntimeException will be thrown.

        This object works with enums as well. The enums in its nature have limited number of members. In convert(ArgumentParser, Argument, String), string value will be converted to one of them. If it cannot be converted, convert(ArgumentParser, Argument, String) will throw ArgumentParserException. This means it already act like a Argument.choices(Object...). Please note that this conversion does not take into account Enum.toString() override. If application passes enums with toString() overridden with the different value than enum name, it may not work like it expects. To take into account Enum.toString() on conversion, use Arguments.enumStringType(Class) instead.

        Parameters:
        type - The type String value should be converted to.

    • Method Detail

      • convert

        public T convert​(ArgumentParser parser,
                 Argument arg,
                 java.lang.String value)
          throws ArgumentParserException
        Description copied from interface: ArgumentType

        Converts value to appropriate type.

        If the objects derived from RuntimeException are thrown in conversion because of invalid input from command line, subclass must catch these exceptions and wrap them in ArgumentParserException and give simple error message to explain what happened briefly.

        Specified by:
        convert in interface ArgumentType<T>
        Parameters:
        parser - The parser.
        arg - The argument this type attached to.
        value - The attribute value.
        Returns:
        Converted object.
        Throws:
        ArgumentParserException - If conversion fails.

      • handleInstantiationError

        private void handleInstantiationError​(java.lang.Exception e)

      • inferMetavar

        public java.lang.String[] inferMetavar()

        Infers metavar based on given type.

        If Boolean class is passed to constructor, this method returns metavar string "{true,false}" for convenience.

        If enum type is passed to constructor, this method returns metavar containing all enum names defined in that type. This uses Enum.name() method, instead of Object.toString() method. If you are looking for the latter, consider to use EnumStringArgumentType.

        Otherwise, returns null.

        Specified by:
        inferMetavar in interface MetavarInference
        Returns:
        inferred array of metavar strings, or null if there is no metavar inferred.
        Since:
        0.7.0
        See Also:
        MetavarInference.inferMetavar()