eu.simuline.util

Class Caster

java.lang.Object

eu.simuline.util.Caster

Direct Known Subclasses:

Caster.Trivial

public abstract class Caster
extends Object

Provides ways to transform instances of various classes into one another. The core method is cast(java.lang.Object): it performs the transformation.

A simple example would be to transform Doubles into eu.simuline.arithmetics.left2right.FPNumbers. Another example is given by BASIC_TYPES. It is the foundation to transform arrays of elementary types to arrays of their wrappers and the other way round such as double[][] and Double[][].

Casters may be used to transform descriptors of objects into these objects. A snippet of typical implementation for the cast(java.lang.Object)-method would be "return new ExaClass(descriptor)" in this case.

Version:

1.0

Author:

Ernst Reissner

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	Caster.Trivial This is a trivial caster.

Field Summary

Fields

Modifier and Type	Field and Description
static Caster	ASSIGNEMENT_COMPATIBLE A trivial caster for which compatibility is assignment compatibility.
static Caster	BASIC_TYPES A trivial caster for which compatibility is assignment compatibility up to wrapping and unwrapping of primitive types.
static Caster	STRICT A trivial caster for which compatibility is equality of classes.

Constructor Summary

Constructors

Constructor and Description
Caster()

Method Summary

Modifier and Type	Method and Description
abstract boolean	areCompatible(Class<?> cls, Object obj) Decides whether the given class and object are compatible with respect to this caster.
abstract Object	cast(Object obj) The return value cast(obj) (which may well be null), may be casted to class cls if areCompatible(java.lang.Class<?>, java.lang.Object) returns true.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ASSIGNEMENT_COMPATIBLE

public static final Caster ASSIGNEMENT_COMPATIBLE

A trivial caster for which compatibility is assignment compatibility.

STRICT

public static final Caster STRICT

A trivial caster for which compatibility is equality of classes.

BASIC_TYPES

public static final Caster BASIC_TYPES

A trivial caster for which compatibility is assignment compatibility up to wrapping and unwrapping of primitive types. Used to implement CollectionsExt.recToArray(Object,Class) as a special case of CollectionsExt.recToArray(Object,Class,Caster).

Constructor Detail

Caster

public Caster()

Method Detail

areCompatible

public abstract boolean areCompatible(Class<?> cls,
                                      Object obj)

Decides whether the given class and object are compatible with respect to this caster.

Parameters:

cls - a Class.

obj - an Object.

Returns:

true if and only if either of the following holds:

• cast(obj) may be casted to cls, i.e. if either cast(obj) == null (which is the case for obj == null) or (sequentially) cls.isInstance(cast(obj)).
• cls is a basic type, cast(obj) != null and (sequentially) cast(obj).getClass() is the corresponding wrapper type.

See Also:

BasicTypesCompatibilityChecker.areCompatible(java.lang.Class<?>, java.lang.Object)

cast

public abstract Object cast(Object obj)

The return value cast(obj) (which may well be null), may be casted to class cls if areCompatible(java.lang.Class<?>, java.lang.Object) returns true.

Parameters:

obj - an arbitrary Object or even null.

Returns:

• null for obj == null.
• null if obj != null but targetClass(obj.getClass()) == null. ****
• either null again or an instance of targetClass(obj.getClass())