public final class Method extends Executable
Method
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 an IllegalArgumentException
if a
narrowing conversion would occur.
Modifier and Type | Method and Description |
---|---|
boolean |
equals(Object obj)
Compares this
Method against the specified object. |
AnnotatedType |
getAnnotatedReturnType()
Returns an
AnnotatedType object that represents the use of a type to
specify the return type of the method/constructor represented by this
Executable. |
<T extends Annotation> |
getAnnotation(Class<T> annotationClass)
Returns this element's annotation for the specified type if
such an annotation is present, else null.
|
Annotation[] |
getDeclaredAnnotations()
Returns annotations that are directly present on this element.
|
Class<?> |
getDeclaringClass()
Returns the
Class object representing the class or interface
that declares the executable represented by this object. |
Object |
getDefaultValue()
Returns the default value for the annotation member represented by
this
Method instance. |
Class<?>[] |
getExceptionTypes()
Returns an array of
Class objects that represent the
types of exceptions declared to be thrown by the underlying
executable represented by this object. |
Type[] |
getGenericExceptionTypes()
Returns an array of
Type objects that represent the
exceptions declared to be thrown by this executable object. |
Type[] |
getGenericParameterTypes()
Returns an array of
Type objects that represent the formal
parameter types, in declaration order, of the executable represented by
this object. |
Type |
getGenericReturnType()
Returns a
Type object that represents the formal return
type of the method represented by this Method object. |
int |
getModifiers()
Returns the Java language modifiers for
the executable represented by this object.
|
String |
getName()
Returns the name of the method represented by this
Method
object, as a String . |
Annotation[][] |
getParameterAnnotations()
Returns an array of arrays of
Annotation s that
represent the annotations on the formal parameters, in
declaration order, of the Executable represented by
this object. |
int |
getParameterCount()
Returns the number of formal parameters (whether explicitly
declared or implicitly declared or neither) for the executable
represented by this object.
|
Class<?>[] |
getParameterTypes()
Returns an array of
Class objects that represent the formal
parameter types, in declaration order, of the executable
represented by this object. |
Class<?> |
getReturnType()
Returns a
Class object that represents the formal return type
of the method represented by this Method object. |
TypeVariable<Method>[] |
getTypeParameters()
Returns an array of
TypeVariable objects that represent the
type variables declared by the generic declaration represented by this
GenericDeclaration object, in declaration order. |
int |
hashCode()
Returns a hashcode for this
Method . |
Object |
invoke(Object obj,
Object... args)
Invokes the underlying method represented by this
Method
object, on the specified object with the specified parameters. |
boolean |
isBridge()
Returns
true if this method is a bridge
method; returns false otherwise. |
boolean |
isDefault()
Returns
true if this method is a default
method; returns false otherwise. |
boolean |
isSynthetic()
Returns
true if this executable is a synthetic
construct; returns false otherwise. |
boolean |
isVarArgs()
Returns
true if this executable was declared to take a
variable number of arguments; returns false otherwise. |
String |
toGenericString()
Returns a string describing this
Method , including
type parameters. |
String |
toString()
Returns a string describing this
Method . |
getAnnotatedExceptionTypes, getAnnotatedParameterTypes, getAnnotatedReceiverType, getAnnotationsByType, getParameters
getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAccessible, isAnnotationPresent, setAccessible, setAccessible
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAnnotationPresent
public Class<?> getDeclaringClass()
Class
object representing the class or interface
that declares the executable represented by this object.getDeclaringClass
in interface Member
getDeclaringClass
in class Executable
public String getName()
Method
object, as a String
.getName
in interface Member
getName
in class Executable
public int getModifiers()
getModifiers
in interface Member
getModifiers
in class Executable
Modifier
public TypeVariable<Method>[] getTypeParameters()
TypeVariable
objects that represent the
type variables declared by the generic declaration represented by this
GenericDeclaration
object, in declaration order. Returns an
array of length 0 if the underlying generic declaration declares no type
variables.getTypeParameters
in interface GenericDeclaration
getTypeParameters
in class Executable
TypeVariable
objects that represent
the type variables declared by this generic declarationGenericSignatureFormatError
- if the generic
signature of this generic declaration does not conform to
the format specified in
The Java™ Virtual Machine Specificationpublic Class<?> getReturnType()
Class
object that represents the formal return type
of the method represented by this Method
object.public Type getGenericReturnType()
Type
object that represents the formal return
type of the method represented by this Method
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.
Type
object that represents the formal return
type of the underlying methodGenericSignatureFormatError
- 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 reasonpublic Class<?>[] getParameterTypes()
Class
objects that represent the formal
parameter types, in declaration order, of the executable
represented by this object. Returns an array of length
0 if the underlying executable takes no parameters.getParameterTypes
in class Executable
public int getParameterCount()
getParameterCount
in class Executable
public Type[] getGenericParameterTypes()
Type
objects that represent the formal
parameter types, in declaration order, of the executable represented by
this object. Returns an array of length 0 if the
underlying executable 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.
getGenericParameterTypes
in class Executable
Type
s that represent the formal
parameter types of the underlying executable, in declaration orderGenericSignatureFormatError
- 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 executable refers to a non-existent type
declarationMalformedParameterizedTypeException
- if any of
the underlying executable's parameter types refer to a parameterized
type that cannot be instantiated for any reasonpublic Class<?>[] getExceptionTypes()
Class
objects that represent the
types of exceptions declared to be thrown by the underlying
executable represented by this object. Returns an array of
length 0 if the executable declares no exceptions in its throws
clause.getExceptionTypes
in class Executable
public Type[] getGenericExceptionTypes()
Type
objects that represent the
exceptions declared to be thrown by this executable object.
Returns an array of length 0 if the underlying executable declares
no exceptions in its throws
clause.
If an exception type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
getGenericExceptionTypes
in class Executable
GenericSignatureFormatError
- if the generic method signature does not conform to the format
specified in
The Java™ Virtual Machine SpecificationTypeNotPresentException
- if the underlying executable's
throws
clause refers to a non-existent type declarationMalformedParameterizedTypeException
- if
the underlying executable's throws
clause refers to a
parameterized type that cannot be instantiated for any reasonpublic boolean equals(Object obj)
Method
against the specified object. Returns
true if the objects are the same. Two Methods
are the same if
they were declared by the same class and have the same name
and formal parameter types and return type.equals
in class Object
obj
- the reference object with which to compare.true
if this object is the same as the obj
argument; false
otherwise.Object.hashCode()
,
HashMap
public int hashCode()
Method
. The hashcode is computed
as the exclusive-or of the hashcodes for the underlying
method's declaring class name and the method's name.hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public String toString()
Method
. 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
or private
first,
and then other modifiers in the following order:
abstract
, default
, static
, final
,
synchronized
, native
, strictfp
.
public String toGenericString()
Method
, 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.
The access modifiers are placed in canonical order as
specified by "The Java Language Specification". This is
public
, protected
or private
first,
and then other modifiers in the following order:
abstract
, default
, static
, final
,
synchronized
, native
, strictfp
.
toGenericString
in class Executable
Method
,
include type parameterspublic Object invoke(Object obj, Object... args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException
Method
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.
obj
- the object the underlying method is invoked fromargs
- the arguments used for the method callobj
with parameters
args
IllegalAccessException
- if this Method
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.public boolean isBridge()
true
if this method is a bridge
method; returns false
otherwise.public boolean isVarArgs()
true
if this executable was declared to take a
variable number of arguments; returns false
otherwise.isVarArgs
in class Executable
true
if an only if this executable was declared
to take a variable number of arguments.public boolean isSynthetic()
true
if this executable is a synthetic
construct; returns false
otherwise.isSynthetic
in interface Member
isSynthetic
in class Executable
public boolean isDefault()
true
if this method is a default
method; returns false
otherwise.
A default method is a public non-abstract instance method, that
is, a non-static method with a body, declared in an interface
type.public Object getDefaultValue()
Method
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.Method
instance.TypeNotPresentException
- if the annotation is of type
Class
and no definition can be found for the
default class value.public <T extends Annotation> T getAnnotation(Class<T> annotationClass)
getAnnotation
in interface AnnotatedElement
getAnnotation
in class Executable
T
- the type of the annotation to query for and return if presentannotationClass
- the Class object corresponding to the
annotation typeNullPointerException
- if the given annotation class is nullpublic Annotation[] getDeclaredAnnotations()
getDeclaredAnnotations
in interface AnnotatedElement
getDeclaredAnnotations
in class Executable
public Annotation[][] getParameterAnnotations()
Annotation
s that
represent the annotations on the formal parameters, in
declaration order, of the Executable
represented by
this object. Synthetic and mandated parameters (see
explanation below), such as the outer "this" parameter to an
inner class constructor will be represented in the returned
array. If the executable has no parameters (meaning no formal,
no synthetic, and no mandated parameters), a zero-length array
will be returned. If the Executable
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.
A compiler may add extra parameters that are implicitly
declared in source ("mandated"), as well as parameters that
are neither implicitly nor explicitly declared in source
("synthetic") to the parameter list for a method. See Parameter
for more information.getParameterAnnotations
in class Executable
Parameter
,
Parameter.getAnnotations()
public AnnotatedType getAnnotatedReturnType()
AnnotatedType
object that represents the use of a type to
specify the return type of the method/constructor represented by this
Executable.
If this Executable
object represents a constructor, the AnnotatedType
object represents the type of the constructed object.
If this Executable
object represents a method, the AnnotatedType
object represents the use of a type to specify the return
type of the method.getAnnotatedReturnType
in class Executable
Executable
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