org.yarnandtail.andhow.api

Interface FlaggableType<T>

All Superinterfaces:

ValueType<T>

All Known Implementing Classes:

FlagType

public interface FlaggableType<T>
extends ValueType<T>

A type which is never null and has a value just by the presence of the property without a value, similar to a 'nix flag behavior.

A FlaggableType could be used for a Property that is expected to be set true or false via a command line argument just by its presence, e.g.:
java MyClass launch
If launch is an AndHow property using a FlaggableType (i.e. FlagProp), launch will be considered true just by its presence.

Method Summary

Modifier and Type	Method and Description
T	parseFlag(String sourceValue) Attempts to parse the passed String into the destination type with flag semantics.

Methods inherited from interface org.yarnandtail.andhow.api.ValueType

cast, getDestinationType, parse, toString

Method Detail

parseFlag

T parseFlag(String sourceValue)
     throws ParsingException

Attempts to parse the passed String into the destination type with flag semantics.

This method behaves as ValueType.parse(String), but with these differences:

• Null is interpreted as 'property is present' and thus set to a non-null value The actual value is implementation dependant - see FlagProp for an example.
• Null is never returned, since the intent to give null sourceValue values a non-null destination value.
• It is not reversible with ValueType.toString(Object)

This method should only be called by loaders that support Flags. For instance, loading a non-null value from the properties file entry 'name = ' would be unexpected, so a properties file loader should use the 'parse' method. However, a command line loader would be expected to support flags, so could call this method instead of 'parse'.

This method may still throw a ParsingException, since non-null values may still be parsed. As with ValueType.parse(String), all trimming (removing whitespace from around a value) should be assumed to already have happened for the incoming sourceValue.

Implementations should be careful to ONLY throw a ParsingException - Integers and other types may throw other unchecked exceptions when trying to convert values, which should be handled in this method and rethrown as a ParsingException.

Parameters:

sourceValue -

Returns:

A non-null value.

Throws:

ParsingException - for any type of failure.