Package org.nuxeo.common.utils

Class ReflectUtils

java.lang.Object

org.nuxeo.common.utils.ReflectUtils

public final class ReflectUtils
extends Object

Since:

2025.14

Method Summary

Modifier and Type	Method	Description
static <O extends B, B> List<B>	downgradeCast(List<O> originalList)	Returns the given list typed with a parent type.
static <T, D, O extends D> Class<T>	retrieveFirstParameterType(Class<O> clazz, Class<D> typedClass)	Retrieves the first generic parameter type T from a class O that extends a typed class D<T, ...>.
static <D, O extends D> Class<?>[]	retrieveParameterTypes(Class<O> clazz, Class<D> typedClass, String parameterName, String... parameterNames)	Retrieves a generic parameter type T from a class O that extends a typed class D<..., T, ...>, by its parameter name.

Methods inherited from class java.lang.Object

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

Method Details

downgradeCast

public static <O extends B,
B> List<B> downgradeCast(List<O> originalList)

Returns the given list typed with a parent type. The benefit of this method is that it checks that the ReflectUtils type is assignable to ReflectUtils type at compile time.

For example when you want a List<Number> from a List<Long>.

 
 List<Long> longList = List.of(1L, 2L, 3L);
 
 // casting List<Long> to List<Number> without the helper
 List<number> previousNumberList = (List<Number>) ((List<?>) longList);
 
 // casting List<Long> to List<Number> with the helper
 List<Number> numberList = ReflectUtils.downgradeCast(longList);
 
 

Type Parameters:

O - the original list type

B - the target parent list type

Parameters:

originalList - the list to downgrade cast

Returns:

the given list typed with a parent type

retrieveFirstParameterType

public static <T,
D,
O extends D> Class<T> retrieveFirstParameterType(Class<O> clazz,
 Class<D> typedClass)

Retrieves the first generic parameter type T from a class O that extends a typed class D<T, ...>.

Type Parameters:

T - the target type to retrieve

D - the type that declares the generic parameter, such as D<T, ...>

O - the type that infers the generic parameter, such as O extends D<T, ...>

Parameters:

clazz - the instance to extract the target type from

typedClass - the type that declares the generic parameter

Returns:

the type from the first generic parameter

retrieveParameterTypes

public static <D,
O extends D> Class<?>[] retrieveParameterTypes(Class<O> clazz,
 Class<D> typedClass,
 String parameterName,
 String... parameterNames)

Retrieves a generic parameter type T from a class O that extends a typed class D<..., T, ...>, by its parameter name.

Type Parameters:

D - the type that declares the generic parameter, such as D<..., T, ..>

O - the type that infers the generic parameter, such as O extends D<..., T, ...>

Parameters:

clazz - the instance to extract the target type from

typedClass - the type that declares the generic parameter

Returns:

the parameterName types from the generic parameters