A 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.
Inherited Constant Summary
Public Method Summary
boolean | |
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> T |
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 {@linkplain Modifier 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 | |
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 . |
Inherited Method Summary
Public Methods
public boolean equals (Object obj)
Compares this 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.
Parameters
obj | the object to compare this instance with. |
---|
Returns
true
if the specified object is equal to thisObject
;false
otherwise.
public 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.
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.
Returns
- an object representing the return type of the method
or constructor represented by this
Executable
public T getAnnotation (Class<T> annotationClass)
Returns this element's annotation for the specified type if such an annotation is present, else null.
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 |
---|
public Annotation[] getDeclaredAnnotations ()
Returns annotations that are directly present on this element. This method ignores inherited annotations. If there are no annotations directly present on this element, the return value is an array of length 0. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
Returns
- annotations directly present on this element
public Class<?> getDeclaringClass ()
Returns the Class
object representing the class or interface
that declares the executable represented by this object.
Returns
- an object representing the declaring class of the underlying member
public Object getDefaultValue ()
Returns the default value for the annotation member represented by
this 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.
Returns
- the default value for the annotation member represented
by this
Method
instance.
Throws
TypeNotPresentException | if the annotation is of type
Class and no definition can be found for the
default class value. |
---|
public 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. Returns an array of
length 0 if the executable declares no exceptions in its throws
clause.
Returns
- the exception types declared as being thrown by the executable this object represents
public Type[] getGenericExceptionTypes ()
Returns an array of 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.
Returns
- an array of Types that represent the exception types thrown by the underlying executable
public Type[] getGenericParameterTypes ()
Returns an array of 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.
Returns
- an array of
Type
s that represent the formal parameter types of the underlying executable, in declaration order
public Type getGenericReturnType ()
Returns a 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.
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 Specification |
---|---|
TypeNotPresentException | if the underlying method's return type refers to a non-existent type declaration |
MalformedParameterizedTypeException | if the underlying method's return typed refers to a parameterized type that cannot be instantiated for any reason |
public int getModifiers ()
Returns the Java language {@linkplain Modifier modifiers} for the executable represented by this object.
Returns
- the Java language modifiers for the underlying member
public String getName ()
Returns the name of the method represented by this Method
object, as a String
.
Returns
- the simple name of the underlying member
public 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. 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.
Returns
- an array of arrays that represent the annotations on the formal and implicit parameters, in declaration order, of the executable represented by this object
public int getParameterCount ()
Returns the number of formal parameters (whether explicitly declared or implicitly declared or neither) for the executable represented by this object.
Returns
- The number of formal parameters for the executable this object represents
public Class[]<?> getParameterTypes ()
Returns an array of 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.
Returns
- the parameter types for the executable this object represents
public Class<?> getReturnType ()
Returns a Class
object that represents the formal return type
of the method represented by this Method
object.
Returns
- the return type for the method this object represents
public 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. Returns an
array of length 0 if the underlying generic declaration declares no type
variables.
Returns
- an array of
TypeVariable
objects that represent the type variables declared by this generic declaration
Throws
GenericSignatureFormatError |
---|
public int hashCode ()
Returns a hashcode for this 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.
Returns
- this object's hash code.
public Object invoke (Object obj, Object... args)
Invokes the underlying method represented by this 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.
Parameters
obj | the object the underlying method is invoked from |
---|---|
args | 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 this Method object
is enforcing Java language access control and the underlying
method is inaccessible. |
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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 ()
Returns true
if this method is a bridge
method; returns false
otherwise.
Returns
- true if and only if this method is a bridge method as defined by the Java Language Specification.
public boolean isDefault ()
Returns 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.
Returns
- true if and only if this method is a default method as defined by the Java Language Specification.
public boolean isSynthetic ()
Returns true
if this executable is a synthetic
construct; returns false
otherwise.
Returns
- true if and only if this executable is a synthetic construct as defined by The Java™ Language Specification.
public boolean isVarArgs ()
Returns true
if this executable was declared to take a
variable number of arguments; returns false
otherwise.
Returns
true
if an only if this executable was declared to take a variable number of arguments.
public String toGenericString ()
Returns a string describing this 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
.
Returns
- a string describing this
Method
, include type parameters
public String toString ()
Returns a string describing this 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
.
Returns
- a string describing this
Method