org.apache.commons.lang3

Class AnnotationUtils

java.lang.Object

org.apache.commons.lang3.AnnotationUtils

public class AnnotationUtils
extends Object

Helper methods for working with Annotation instances.

This class contains various utility methods that make working with annotations simpler.

Annotation instances are always proxy objects; unfortunately dynamic proxies cannot be depended upon to know how to implement certain methods in the same manner as would be done by "natural" Annotations. The methods presented in this class can be used to avoid that possibility. It is of course also possible for dynamic proxies to actually delegate their e.g. Annotation.equals(Object)/Annotation.hashCode()/ Annotation.toString() implementations to AnnotationUtils.

#ThreadSafe#

Since:

3.0

Constructor Summary

Constructors

Constructor and Description
AnnotationUtils() AnnotationUtils instances should NOT be constructed in standard programming.

Method Summary

Modifier and Type	Method and Description
static boolean	equals(Annotation a1, Annotation a2) Checks if two annotations are equal using the criteria for equality presented in the Annotation.equals(Object) API docs.
static int	hashCode(Annotation a) Generate a hash code for the given annotation using the algorithm presented in the Annotation.hashCode() API docs.
static boolean	isValidAnnotationMemberType(Class<?> type) Checks if the specified type is permitted as an annotation member.
static String	toString(Annotation a) Generate a string representation of an Annotation, as suggested by Annotation.toString().

Methods inherited from class java.lang.Object

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

Constructor Detail

AnnotationUtils

public AnnotationUtils()

AnnotationUtils instances should NOT be constructed in standard programming. Instead, the class should be used statically.

This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

equals

public static boolean equals(Annotation a1,
                             Annotation a2)

Checks if two annotations are equal using the criteria for equality presented in the Annotation.equals(Object) API docs.

Parameters:

a1 - the first Annotation to compare, null returns false unless both are null

a2 - the second Annotation to compare, null returns false unless both are null

Returns:

true if the two annotations are equal or both null

hashCode

public static int hashCode(Annotation a)

Generate a hash code for the given annotation using the algorithm presented in the Annotation.hashCode() API docs.

Parameters:

a - the Annotation for a hash code calculation is desired, not null

Returns:

the calculated hash code

Throws:

RuntimeException - if an Exception is encountered during annotation member access

IllegalStateException - if an annotation method invocation returns null

toString

public static String toString(Annotation a)

Generate a string representation of an Annotation, as suggested by Annotation.toString().

Parameters:

a - the annotation of which a string representation is desired

Returns:

the standard string representation of an annotation, not null

isValidAnnotationMemberType

public static boolean isValidAnnotationMemberType(Class<?> type)

Checks if the specified type is permitted as an annotation member.

The Java language specification only permits certain types to be used in annotations. These include String, Class, primitive types, Annotation, Enum, and single-dimensional arrays of these types.

Parameters:

type - the type to check, null

Returns:

true if the type is a valid type to use in an annotation