Package org.apache.commons.lang3

Class AnnotationUtils

  • public class AnnotationUtils
extends java.lang.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 Description
      AnnotationUtils()
      AnnotationUtils instances should NOT be constructed in standard programming.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static boolean equals​(java.lang.annotation.Annotation a1, java.lang.annotation.Annotation a2)
      Checks if two annotations are equal using the criteria for equality presented in the Annotation.equals(Object) API docs.
      static int hashCode​(java.lang.annotation.Annotation a)
      Generate a hash code for the given annotation using the algorithm presented in the Annotation.hashCode() API docs.
      static boolean isValidAnnotationMemberType​(java.lang.Class<?> type)
      Checks if the specified type is permitted as an annotation member.
      static java.lang.String toString​(java.lang.annotation.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​(java.lang.annotation.Annotation a1,
                             java.lang.annotation.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​(java.lang.annotation.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:
        java.lang.RuntimeException - if an Exception is encountered during annotation member access
        java.lang.IllegalStateException - if an annotation method invocation returns null

      • toString

        public static java.lang.String toString​(java.lang.annotation.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​(java.lang.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