de.alpharogroup.lang

Class TypeArgumentsExtensions

java.lang.Object

de.alpharogroup.lang.TypeArgumentsExtensions

public class TypeArgumentsExtensions
extends Object

The class TypeArgumentsExtensions is a utility class for getting the type arguments a child class has used to extend a generic base class. It is inspired from the article Reflecting generics by Ian Robertson at http://www.artima.com/weblogs/viewpost.jsp?thread=208860. In the comments someone asked if we are allowed to use the source code from the article. The answer of Ian Robertson is: Absolutely, you may use this code. "Consider it open sourced".

Constructor Summary

Constructors

Constructor and Description
TypeArgumentsExtensions()

Method Summary

Modifier and Type	Method and Description
static <T> Class<?>	getFirstTypeArgument(Class<T> baseClass, Class<? extends T> childClass) Gets the first type argument from the childClass.
static <T> Class<?>	getTypeArgument(Class<T> baseClass, Class<? extends T> childClass, int index) Gets the type argument from the childClass at the given index or null if it does not exists.
static <T> List<Class<?>>	getTypeArguments(Class<T> baseClass, Class<? extends T> childClass) Get the actual type arguments a child class has used to extend a generic base class.

Methods inherited from class java.lang.Object

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

Constructor Detail

TypeArgumentsExtensions

public TypeArgumentsExtensions()

Method Detail

getFirstTypeArgument

public static <T> Class<?> getFirstTypeArgument(Class<T> baseClass,
                                                Class<? extends T> childClass)

Gets the first type argument from the childClass.

Type Parameters:

T - the generic type of the baseClass

Parameters:

baseClass - the base class

childClass - the child class

Returns:

the first type argument

getTypeArgument

public static <T> Class<?> getTypeArgument(Class<T> baseClass,
                                           Class<? extends T> childClass,
                                           int index)

Gets the type argument from the childClass at the given index or null if it does not exists.

Type Parameters:

T - the generic type of the baseClass

Parameters:

baseClass - the base class

childClass - the child class

index - the index of the type argument

Returns:

the type argument from the childClass at the given index or null if it does not exists.

getTypeArguments

public static <T> List<Class<?>> getTypeArguments(Class<T> baseClass,
                                                  Class<? extends T> childClass)

Get the actual type arguments a child class has used to extend a generic base class.

Type Parameters:

T - the generic type of the baseClass

Parameters:

baseClass - the base class

childClass - the child class

Returns:

a list of the raw classes for the actual type arguments.