org.yarnandtail.andhow.api

Interface ValueType<T>

All Known Subinterfaces:

FlaggableType<T>

All Known Implementing Classes:

BaseValueType, BigDecType, BolType, DblType, FlagType, IntType, LngType, LocalDateTimeType, StrType

public interface ValueType<T>

The datatype and type conversion handler of a Property.

Handles parsing and casting of Strings and Objects to the destination type represented by an instance of a ValueType.

Method Summary

Modifier and Type	Method and Description
T	cast(Object o) Attempt to cast the object to the generic type T, which is a concrete class in subclasses.
Class<T>	getDestinationType()
T	parse(String sourceValue) Attempts to parse the passed String into the destinationType.
String	toString(T value) Converts an instance of the destination type to String.

Method Detail

getDestinationType

Class<T> getDestinationType()

parse

T parse(String sourceValue)
 throws ParsingException

Attempts to parse the passed String into the destinationType.

All trimming (removing whitespace from around a value) should be assumed to already have happened for the incoming sourceValue by a Trimmer. A null sourceValue always parses to null, so callers may optionally skip calling parse with a null value.

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.

This method and toString(T) should be reversible: The object generated here should be toString-able to a String equal to the one passed this method. Though this may not be possible for Boolean types, which may have multiple possible string representations for True or False.

Parameters:

sourceValue -

Returns:

null if null, or a value of type T

Throws:

ParsingException - for any type of failure.

toString

String toString(T value)

Converts an instance of the destination type to String. For most types, simply calling T.toString() is a good enough implementation. For dates, times and other more complex types, more detailed conversion may be needed. This method and parse() should be reversible: The string generated here should be parsable to an object equal to the one passed this method.

Parameters:

value -

Returns:

null if the passed value is null.

cast

T cast(Object o)
throws RuntimeException

Attempt to cast the object to the generic type T, which is a concrete class in subclasses.

AndHow uses this internally to cast values known to already be of type T, but were stored in a generic way. If used for unknown types that are not castable to T, it will throw a RuntimeException, though this should never happen unless used by application code.

Parameters:

o - Object to cast

Returns:

A cast obeject

Throws:

RuntimeException