Class AnnotationUtils
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" Annotation
s.
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
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final ToStringStyle
A style that prints annotations as recommended. -
Constructor Summary
ConstructorsConstructorDescriptionAnnotationUtils
instances should NOT be constructed in standard programming. -
Method Summary
Modifier and TypeMethodDescriptionprivate static boolean
annotationArrayMemberEquals
(Annotation[] a1, Annotation[] a2) Helper method for comparing two arrays of annotations.private static boolean
arrayMemberEquals
(Class<?> componentType, Object o1, Object o2) Helper method for comparing two objects of an array type.private static int
arrayMemberHash
(Class<?> componentType, Object o) Helper method for generating a hash code for an array.static boolean
equals
(Annotation a1, Annotation a2) Checks if two annotations are equal using the criteria for equality presented in theAnnotation.equals(Object)
API docs.static int
Generate a hash code for the given annotation using the algorithm presented in theAnnotation.hashCode()
API docs.private static int
hashMember
(String name, Object value) Helper method for generating a hash code for a member of an annotation.static boolean
isValidAnnotationMemberType
(Class<?> type) Checks if the specified type is permitted as an annotation member.private static boolean
memberEquals
(Class<?> type, Object o1, Object o2) Helper method for checking whether two objects of the given type are equal.static String
Generate a string representation of an Annotation, as suggested byAnnotation.toString()
.
-
Field Details
-
TO_STRING_STYLE
A style that prints annotations as recommended.
-
-
Constructor Details
-
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 Details
-
equals
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
returnsfalse
unless both arenull
a2
- the second Annotation to compare,null
returnsfalse
unless both arenull
- Returns:
true
if the two annotations areequal
or bothnull
-
hashCode
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, notnull
- Returns:
- the calculated hash code
- Throws:
RuntimeException
- if anException
is encountered during annotation member accessIllegalStateException
- if an annotation method invocation returnsnull
-
toString
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
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
-
hashMember
Helper method for generating a hash code for a member of an annotation.- Parameters:
name
- the name of the membervalue
- the value of the member- Returns:
- a hash code for this member
-
memberEquals
Helper method for checking whether two objects of the given type are equal. This method is used to compare the parameters of two annotation instances.- Parameters:
type
- the type of the objects to be comparedo1
- the first objecto2
- the second object- Returns:
- a flag whether these objects are equal
-
arrayMemberEquals
Helper method for comparing two objects of an array type.- Parameters:
componentType
- the component type of the arrayo1
- the first objecto2
- the second object- Returns:
- a flag whether these objects are equal
-
annotationArrayMemberEquals
Helper method for comparing two arrays of annotations.- Parameters:
a1
- the first arraya2
- the second array- Returns:
- a flag whether these arrays are equal
-
arrayMemberHash
Helper method for generating a hash code for an array.- Parameters:
componentType
- the component type of the arrayo
- the array- Returns:
- a hash code for the specified array
-