| JavaTM 2 Platform Std. Ed. v1.6.0
java.lang.reflect
Class Method
java.lang.Object
 java.lang.reflect.AccessibleObject
java.lang.reflect.Method
- All Implemented Interfaces:
- AnnotatedElement, GenericDeclaration, Member
public final class Method - extends AccessibleObject
- implements GenericDeclaration, Member
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.
- See Also:
Member,
Class,
Class.getMethods(),
Class.getMethod(String, Class[]),
Class.getDeclaredMethods(),
Class.getDeclaredMethod(String, Class[])
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Method Summary |
boolean |
equals(Object obj)
Compares this Method against the specified object. |
|
getAnnotation(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 the Class object representing the class or interface
that declares the method represented by this Method 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 the exceptions declared to be thrown
by the underlying method
represented by this Method object. |
Type[] |
getGenericExceptionTypes()
Returns an array of Type objects that represent the
exceptions declared to be thrown by this Method object. |
Type[] |
getGenericParameterTypes()
Returns an array of Type objects that represent the formal
parameter types, in declaration order, of the method represented by
this Method 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 method represented
by this Method object, as an integer. |
String |
getName()
Returns the name of the method represented by this Method
object, as a String. |
Annotation[][] |
getParameterAnnotations()
Returns an array of arrays that represent the annotations on the formal
parameters, in declaration order, of the method represented by
this Method object. |
Class<?>[] |
getParameterTypes()
Returns an array of Class objects that represent the formal
parameter types, in declaration order, of the method
represented by this Method 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 |
isSynthetic()
Returns true if this method is a synthetic
method; returns false otherwise. |
boolean |
isVarArgs()
Returns true if this method 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. |
getDeclaringClass
public Class<?> getDeclaringClass()
- Returns the
Class object representing the class or interface
that declares the method represented by this Method object.
- Specified by:
getDeclaringClass in interface Member
- Returns:
- an object representing the declaring class of the
underlying member
getName
public String getName()
- Returns the name of the method represented by this
Method
object, as a String.
- Specified by:
getName in interface Member
- Returns:
- the simple name of the underlying member
getModifiers
public int getModifiers()
- Returns the Java language modifiers for the method represented
by this
Method object, as an integer. The Modifier class should
be used to decode the modifiers.
- Specified by:
getModifiers in interface Member
- Returns:
- the Java language modifiers for the underlying member
- See Also:
Modifier
getTypeParameters
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.
- Specified by:
getTypeParameters in interface GenericDeclaration
- 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,
3rd edition- Since:
- 1.5
getReturnType
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
getGenericReturnType
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, 3rd edition
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- Since:
- 1.5
getParameterTypes
public Class<?>[] getParameterTypes()
- Returns an array of
Class objects that represent the formal
parameter types, in declaration order, of the method
represented by this Method object. Returns an array of length
0 if the underlying method takes no parameters.
- Returns:
- the parameter types for the method this object
represents
getGenericParameterTypes
public Type[] getGenericParameterTypes()
- Returns an array of Type objects that represent the formal
parameter types, in declaration order, of the method represented by
this Method 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 Specification, 3rd edition
TypeNotPresentException - if any of the parameter
types of the underlying method refers to a non-existent type
declaration
MalformedParameterizedTypeException - if any of
the underlying method's parameter types refer to a parameterized
type that cannot be instantiated for any reason- Since:
- 1.5
getExceptionTypes
public Class<?>[] getExceptionTypes()
- Returns an array of
Class objects that represent
the types of the exceptions declared to be thrown
by the underlying method
represented by this Method object. Returns an array of length
0 if the method declares no exceptions in its throws clause.
- Returns:
- the exception types declared as being thrown by the
method this object represents
getGenericExceptionTypes
public Type[] getGenericExceptionTypes()
- Returns an array of Type objects that represent the
exceptions declared to be thrown by this Method object.
Returns an array of length 0 if the underlying method declares
no exceptions in its throws clause.
If an exception type is a parameterized type, the Type
object returned for it must accurately reflect the actual type
parameters used in the source code.
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 Specification, 3rd edition
TypeNotPresentException - if the underlying method's
throws clause refers to a non-existent type declaration
MalformedParameterizedTypeException - if
the underlying method's throws clause refers to a
parameterized type that cannot be instantiated for any reason- Since:
- 1.5
equals
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.
- Overrides:
equals in class Object
- 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(),
Hashtable
hashCode
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.
- Overrides:
hashCode in class Object
- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object),
Hashtable
toString
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, static, final,
synchronized, native.
- Overrides:
toString in class Object
- Returns:
- a string representation of the object.
toGenericString
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. 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 or private first,
and then other modifiers in the following order:
abstract, static, final,
synchronized native.
- Returns:
- a string describing this
Method,
include type parameters - Since:
- 1.5
invoke
public Object invoke(Object obj,
Object... args)
throws IllegalAccessException,
IllegalArgumentException,
InvocationTargetException
- 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 fromargs - the arguments used for the method call
- Returns:
- the result of dispatching the method represented by
this object on
obj with parameters
args
- Throws:
IllegalAccessException - if this Method object
enforces 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.
isBridge
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.
- Since:
- 1.5
isVarArgs
public boolean isVarArgs()
- Returns true if this method was declared to take
a variable number of arguments; returns false
otherwise.
- Returns:
- true if an only if this method was declared to
take a variable number of arguments.
- Since:
- 1.5
isSynthetic
public boolean isSynthetic()
- Returns true if this method is a synthetic
method; returns false otherwise.
- Specified by:
isSynthetic in interface Member
- Returns:
- true if and only if this method is a synthetic
method as defined by the Java Language Specification.
- Since:
- 1.5
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 interface AnnotatedElement- Overrides:
getAnnotation in class AccessibleObject
- 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
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 interface AnnotatedElement- Overrides:
getDeclaredAnnotations in class AccessibleObject
- Returns:
- All annotations directly present on this element
- Since:
- 1.5
getDefaultValue
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.- Since:
- 1.5
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
this Method 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
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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