Knopflerfish OSGi 5.2.0

org.osgi.service.blueprint.container
Class ReifiedType

java.lang.Object
  extended by org.osgi.service.blueprint.container.ReifiedType

public class ReifiedType
extends java.lang.Object

Provides access to a concrete type and its optional generic type parameters.

Java 5 and later support generic types. These types consist of a raw class with type parameters. This class models such a Type class but ensures that the type is reified. Reification means that the Type graph associated with a Java 5 Type instance is traversed until the type becomes a concrete class. This class is available with the getRawClass() method. The optional type parameters are recursively represented as Reified Types.

In Java 1.4, a class has by definition no type parameters. This class implementation provides the Reified Type for Java 1.4 by making the raw class the Java 1.4 class and using a Reified Type based on the Object class for any requested type parameter.

A Blueprint extender implementations can subclass this class and provide access to the generic type parameter graph for conversion. Such a subclass must reify the different Java 5 Type instances into the reified form. That is, a form where the raw Class is available with its optional type parameters as Reified Types.

Author:
$Id: 0e2e040d652f98008e853cd6b1642626a3ec05c1 $
Immutable

Constructor Summary
ReifiedType(java.lang.Class<?> clazz)
          Create a Reified Type for a raw Java class without any generic type parameters.
 
Method Summary
 ReifiedType getActualTypeArgument(int i)
          Return a type parameter for this type.
 java.lang.Class<?> getRawClass()
          Return the raw class represented by this type.
 int size()
          Return the number of type parameters for this type.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ReifiedType

public ReifiedType(java.lang.Class<?> clazz)
Create a Reified Type for a raw Java class without any generic type parameters. Subclasses can provide the optional generic type parameter information. Without subclassing, this instance has no type parameters.

Parameters:
clazz - The raw class of the Reified Type.
Method Detail

getRawClass

public java.lang.Class<?> getRawClass()
Return the raw class represented by this type. The raw class represents the concrete class that is associated with a type declaration. This class could have been deduced from the generics type parameter graph of the declaration. For example, in the following example:
 Map<String, ? extends Metadata>
 
The raw class is the Map class.

Returns:
The raw class represented by this type.

getActualTypeArgument

public ReifiedType getActualTypeArgument(int i)
Return a type parameter for this type. The type parameter refers to a parameter in a generic type declaration given by the zero-based index i. For example, in the following example:
 Map<String, ? extends Metadata>
 
type parameter 0 is String, and type parameter 1 is Metadata.

This implementation returns a Reified Type that has Object as class. Any object is assignable to Object and therefore no conversion is then necessary. This is compatible with versions of Java language prior to Java 5. This method should be overridden by a subclass that provides access to the generic type parameter information for Java 5 and later.

Parameters:
i - The zero-based index of the requested type parameter.
Returns:
The ReifiedType for the generic type parameter at the specified index.

size

public int size()
Return the number of type parameters for this type.

This implementation returns 0. This method should be overridden by a subclass that provides access to the generic type parameter information for Java 5 and later.

Returns:
The number of type parameters for this type.

Knopflerfish OSGi 5.2.0