- java.lang.Object
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- java.lang.reflect.AccessibleObject
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- java.lang.reflect.Method
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- All Implemented Interfaces:
- AnnotatedElement, GenericDeclaration, Member
public final class Method extends AccessibleObject implements GenericDeclaration, Member
AMethod
provides information about, and access to, a single method on a class or interface. The reflected method may be a class method or an instance method (including an abstract method).A
Method
permits widening conversions to occur when matching the actual parameters to invoke with the underlying method's formal parameters, but it throws anIllegalArgumentException
if a narrowing conversion would occur.
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Method Summary
Methods Modifier and Type Method and Description boolean
equals(Object obj)
Compares thisMethod
against the specified object.<T extends Annotation>
TgetAnnotation(Class<T> annotationClass)
Returns this element's annotation for the specified type if such an annotation is present, else null.Annotation[]
getDeclaredAnnotations()
Returns all annotations that are directly present on this element.Class<?>
getDeclaringClass()
Returns theClass
object representing the class or interface that declares the method represented by thisMethod
object.Object
getDefaultValue()
Returns the default value for the annotation member represented by thisMethod
instance.Class<?>[]
getExceptionTypes()
Returns an array ofClass
objects that represent the types of the exceptions declared to be thrown by the underlying method represented by thisMethod
object.Type[]
getGenericExceptionTypes()
Returns an array ofType
objects that represent the exceptions declared to be thrown by thisMethod
object.Type[]
getGenericParameterTypes()
Returns an array ofType
objects that represent the formal parameter types, in declaration order, of the method represented by thisMethod
object.Type
getGenericReturnType()
Returns aType
object that represents the formal return type of the method represented by thisMethod
object.int
getModifiers()
Returns the Java language modifiers for the method represented by thisMethod
object, as an integer.String
getName()
Returns the name of the method represented by thisMethod
object, as aString
.Annotation[][]
getParameterAnnotations()
Returns an array of arrays that represent the annotations on the formal parameters, in declaration order, of the method represented by thisMethod
object.Class<?>[]
getParameterTypes()
Returns an array ofClass
objects that represent the formal parameter types, in declaration order, of the method represented by thisMethod
object.Class<?>
getReturnType()
Returns aClass
object that represents the formal return type of the method represented by thisMethod
object.TypeVariable<Method>[]
getTypeParameters()
Returns an array ofTypeVariable
objects that represent the type variables declared by the generic declaration represented by thisGenericDeclaration
object, in declaration order.int
hashCode()
Returns a hashcode for thisMethod
.Object
invoke(Object obj, Object... args)
Invokes the underlying method represented by thisMethod
object, on the specified object with the specified parameters.boolean
isBridge()
Returnstrue
if this method is a bridge method; returnsfalse
otherwise.boolean
isSynthetic()
Returnstrue
if this method is a synthetic method; returnsfalse
otherwise.boolean
isVarArgs()
Returnstrue
if this method was declared to take a variable number of arguments; returnsfalse
otherwise.String
toGenericString()
Returns a string describing thisMethod
, including type parameters.String
toString()
Returns a string describing thisMethod
.-
Methods inherited from class java.lang.reflect.AccessibleObject
getAnnotations, isAccessible, isAnnotationPresent, setAccessible, setAccessible
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Method Detail
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getDeclaringClass
public Class<?> getDeclaringClass()
Returns theClass
object representing the class or interface that declares the method represented by thisMethod
object.- Specified by:
getDeclaringClass
in interfaceMember
- Returns:
- an object representing the declaring class of the underlying member
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getName
public String getName()
Returns the name of the method represented by thisMethod
object, as aString
.
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getModifiers
public int getModifiers()
Returns the Java language modifiers for the method represented by thisMethod
object, as an integer. TheModifier
class should be used to decode the modifiers.- Specified by:
getModifiers
in interfaceMember
- Returns:
- the Java language modifiers for the underlying member
- See Also:
Modifier
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getTypeParameters
public TypeVariable<Method>[] getTypeParameters()
Returns an array ofTypeVariable
objects that represent the type variables declared by the generic declaration represented by thisGenericDeclaration
object, in declaration order. Returns an array of length 0 if the underlying generic declaration declares no type variables.- Specified by:
getTypeParameters
in interfaceGenericDeclaration
- Returns:
- an array of
TypeVariable
objects that represent the type variables declared by this generic declaration - Throws:
GenericSignatureFormatError
- if the generic signature of this generic declaration does not conform to the format specified in The Java™ Virtual Machine Specification- Since:
- 1.5
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getReturnType
public Class<?> getReturnType()
Returns aClass
object that represents the formal return type of the method represented by thisMethod
object.- Returns:
- the return type for the method this object represents
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getGenericReturnType
public Type getGenericReturnType()
Returns aType
object that represents the formal return type of the method represented by thisMethod
object.If the return type is a parameterized type, the
Type
object returned must accurately reflect the actual type parameters used in the source code.If the return type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
- Returns:
- a
Type
object that represents the formal return type of the underlying method - Throws:
GenericSignatureFormatError
- if the generic method signature does not conform to the format specified in The Java™ Virtual Machine SpecificationTypeNotPresentException
- if the underlying method's return type refers to a non-existent type declarationMalformedParameterizedTypeException
- if the underlying method's return typed refers to a parameterized type that cannot be instantiated for any reason- Since:
- 1.5
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getParameterTypes
public Class<?>[] getParameterTypes()
Returns an array ofClass
objects that represent the formal parameter types, in declaration order, of the method represented by thisMethod
object. Returns an array of length 0 if the underlying method takes no parameters.- Returns:
- the parameter types for the method this object represents
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getGenericParameterTypes
public Type[] getGenericParameterTypes()
Returns an array ofType
objects that represent the formal parameter types, in declaration order, of the method represented by thisMethod
object. Returns an array of length 0 if the underlying method takes no parameters.If a formal parameter type is a parameterized type, the
Type
object returned for it must accurately reflect the actual type parameters used in the source code.If a formal parameter type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
- Returns:
- an array of Types that represent the formal parameter types of the underlying method, in declaration order
- Throws:
GenericSignatureFormatError
- if the generic method signature does not conform to the format specified in The Java™ Virtual Machine SpecificationTypeNotPresentException
- if any of the parameter types of the underlying method refers to a non-existent type declarationMalformedParameterizedTypeException
- if any of the underlying method's parameter types refer to a parameterized type that cannot be instantiated for any reason- Since:
- 1.5
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getExceptionTypes
public Class<?>[] getExceptionTypes()
Returns an array ofClass
objects that represent the types of the exceptions declared to be thrown by the underlying method represented by thisMethod
object. Returns an array of length 0 if the method declares no exceptions in itsthrows
clause.- Returns:
- the exception types declared as being thrown by the method this object represents
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getGenericExceptionTypes
public Type[] getGenericExceptionTypes()
Returns an array ofType
objects that represent the exceptions declared to be thrown by thisMethod
object. Returns an array of length 0 if the underlying method declares no exceptions in itsthrows
clause.If an exception type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
- Returns:
- an array of Types that represent the exception types thrown by the underlying method
- Throws:
GenericSignatureFormatError
- if the generic method signature does not conform to the format specified in The Java™ Virtual Machine SpecificationTypeNotPresentException
- if the underlying method'sthrows
clause refers to a non-existent type declarationMalformedParameterizedTypeException
- if the underlying method'sthrows
clause refers to a parameterized type that cannot be instantiated for any reason- Since:
- 1.5
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equals
public boolean equals(Object obj)
Compares thisMethod
against the specified object. Returns true if the objects are the same. TwoMethods
are the same if they were declared by the same class and have the same name and formal parameter types and return type.- Overrides:
equals
in classObject
- Parameters:
obj
- the reference object with which to compare.- Returns:
true
if this object is the same as the obj argument;false
otherwise.- See Also:
Object.hashCode()
,HashMap
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hashCode
public int hashCode()
Returns a hashcode for thisMethod
. The hashcode is computed as the exclusive-or of the hashcodes for the underlying method's declaring class name and the method's name.- Overrides:
hashCode
in classObject
- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
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toString
public String toString()
Returns a string describing thisMethod
. The string is formatted as the method access modifiers, if any, followed by the method return type, followed by a space, followed by the class declaring the method, followed by a period, followed by the method name, followed by a parenthesized, comma-separated list of the method's formal parameter types. If the method throws checked exceptions, the parameter list is followed by a space, followed by the word throws followed by a comma-separated list of the thrown exception types. For example:public boolean java.lang.Object.equals(java.lang.Object)
The access modifiers are placed in canonical order as specified by "The Java Language Specification". This is
public
,protected
orprivate
first, and then other modifiers in the following order:abstract
,static
,final
,synchronized
,native
,strictfp
.
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toGenericString
public String toGenericString()
Returns a string describing thisMethod
, including type parameters. The string is formatted as the method access modifiers, if any, followed by an angle-bracketed comma-separated list of the method's type parameters, if any, followed by the method's generic return type, followed by a space, followed by the class declaring the method, followed by a period, followed by the method name, followed by a parenthesized, comma-separated list of the method's generic formal parameter types. If this method was declared to take a variable number of arguments, instead of denoting the last parameter as "Type[]", it is denoted as "Type...". A space is used to separate access modifiers from one another and from the type parameters or return type. If there are no type parameters, the type parameter list is elided; if the type parameter list is present, a space separates the list from the class name. If the method is declared to throw exceptions, the parameter list is followed by a space, followed by the word throws followed by a comma-separated list of the generic thrown exception types. If there are no type parameters, the type parameter list is elided.The access modifiers are placed in canonical order as specified by "The Java Language Specification". This is
public
,protected
orprivate
first, and then other modifiers in the following order:abstract
,static
,final
,synchronized
,native
,strictfp
.- Returns:
- a string describing this
Method
, include type parameters - Since:
- 1.5
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invoke
public Object invoke(Object obj, Object... args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException
Invokes the underlying method represented by thisMethod
object, on the specified object with the specified parameters. Individual parameters are automatically unwrapped to match primitive formal parameters, and both primitive and reference parameters are subject to method invocation conversions as necessary.If the underlying method is static, then the specified
obj
argument is ignored. It may be null.If the number of formal parameters required by the underlying method is 0, the supplied
args
array may be of length 0 or null.If the underlying method is an instance method, it is invoked using dynamic method lookup as documented in The Java Language Specification, Second Edition, section 15.12.4.4; in particular, overriding based on the runtime type of the target object will occur.
If the underlying method is static, the class that declared the method is initialized if it has not already been initialized.
If the method completes normally, the value it returns is returned to the caller of invoke; if the value has a primitive type, it is first appropriately wrapped in an object. However, if the value has the type of an array of a primitive type, the elements of the array are not wrapped in objects; in other words, an array of primitive type is returned. If the underlying method return type is void, the invocation returns null.
- Parameters:
obj
- the object the underlying method is invoked fromargs
- the arguments used for the method call- Returns:
- the result of dispatching the method represented by
this object on
obj
with parametersargs
- Throws:
IllegalAccessException
- if thisMethod
object is enforcing Java language access control and the underlying method is inaccessible.IllegalArgumentException
- if the method is an instance method and the specified object argument is not an instance of the class or interface declaring the underlying method (or of a subclass or implementor thereof); if the number of actual and formal parameters differ; if an unwrapping conversion for primitive arguments fails; or if, after possible unwrapping, a parameter value cannot be converted to the corresponding formal parameter type by a method invocation conversion.InvocationTargetException
- if the underlying method throws an exception.NullPointerException
- if the specified object is null and the method is an instance method.ExceptionInInitializerError
- if the initialization provoked by this method fails.
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isBridge
public boolean isBridge()
Returnstrue
if this method is a bridge method; returnsfalse
otherwise.- Returns:
- true if and only if this method is a bridge method as defined by the Java Language Specification.
- Since:
- 1.5
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isVarArgs
public boolean isVarArgs()
Returnstrue
if this method was declared to take a variable number of arguments; returnsfalse
otherwise.- Returns:
true
if an only if this method was declared to take a variable number of arguments.- Since:
- 1.5
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isSynthetic
public boolean isSynthetic()
Returnstrue
if this method is a synthetic method; returnsfalse
otherwise.- Specified by:
isSynthetic
in interfaceMember
- Returns:
- true if and only if this method is a synthetic method as defined by the Java Language Specification.
- Since:
- 1.5
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getAnnotation
public <T extends Annotation> T getAnnotation(Class<T> annotationClass)
Description copied from interface:AnnotatedElement
Returns this element's annotation for the specified type if such an annotation is present, else null.- Specified by:
getAnnotation
in interfaceAnnotatedElement
- Overrides:
getAnnotation
in classAccessibleObject
- Parameters:
annotationClass
- the Class object corresponding to the annotation type- Returns:
- this element's annotation for the specified annotation type if present on this element, else null
- Throws:
NullPointerException
- if the given annotation class is null- Since:
- 1.5
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getDeclaredAnnotations
public Annotation[] getDeclaredAnnotations()
Description copied from interface:AnnotatedElement
Returns all annotations that are directly present on this element. Unlike the other methods in this interface, this method ignores inherited annotations. (Returns an array of length zero if no annotations are directly present on this element.) The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.- Specified by:
getDeclaredAnnotations
in interfaceAnnotatedElement
- Overrides:
getDeclaredAnnotations
in classAccessibleObject
- Returns:
- All annotations directly present on this element
- Since:
- 1.5
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getDefaultValue
public Object getDefaultValue()
Returns the default value for the annotation member represented by thisMethod
instance. If the member is of a primitive type, an instance of the corresponding wrapper type is returned. Returns null if no default is associated with the member, or if the method instance does not represent a declared member of an annotation type.- Returns:
- the default value for the annotation member represented
by this
Method
instance. - Throws:
TypeNotPresentException
- if the annotation is of typeClass
and no definition can be found for the default class value.- Since:
- 1.5
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getParameterAnnotations
public Annotation[][] getParameterAnnotations()
Returns an array of arrays that represent the annotations on the formal parameters, in declaration order, of the method represented by thisMethod
object. (Returns an array of length zero if the underlying method is parameterless. If the method has one or more parameters, a nested array of length zero is returned for each parameter with no annotations.) The annotation objects contained in the returned arrays are serializable. The caller of this method is free to modify the returned arrays; it will have no effect on the arrays returned to other callers.- Returns:
- an array of arrays that represent the annotations on the formal parameters, in declaration order, of the method represented by this Method object
- Since:
- 1.5
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