java.lang.reflect.Method

All Implemented Interfaces:: AnnotatedElement, GenericDeclaration, Member

public final class Method extends Executable

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.

Since:

1.1

See Also:

Field Summary

Fields declared in interface java.lang.reflect.Member
DECLARED, PUBLIC
Method Summary

Modifier and Type

Method

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> 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 method 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 Annotations 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.

void

setAccessible(boolean flag)

Set the accessible flag for this reflected object to the indicated boolean value.

String

toGenericString()

Returns a string describing this Method, including type parameters.

String

toString()

Returns a string describing this Method.

Methods declared in class java.lang.reflect.Executable
accessFlags, getAnnotatedExceptionTypes, getAnnotatedParameterTypes, getAnnotatedReceiverType, getAnnotationsByType, getParameters

Methods declared in class java.lang.reflect.AccessibleObject
canAccess, getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAccessible, isAnnotationPresent, setAccessible, trySetAccessible

Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods declared in interface java.lang.reflect.AnnotatedElement
getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAnnotationPresent

Method Details
- setAccessible
  public void setAccessible(boolean flag)
  
  Description copied from class: AccessibleObject
  
  Set the accessible flag for this reflected object to the indicated boolean value. A value of true indicates that the reflected object should suppress checks for Java language access control when it is used. A value of false indicates that the reflected object should enforce checks for Java language access control when it is used, with the variation noted in the class description.
  This method may be used by a caller in class C to enable access to a member of declaring class D if any of the following hold:
  
  C and D are in the same module.
  
  The member is public and D is public in a package that the module containing D exports to at least the module containing C.
  
  The member is protected static, D is public in a package that the module containing D exports to at least the module containing C, and C is a subclass of D.
  
  D is in a package that the module containing D opens to at least the module containing C. All packages in unnamed and open modules are open to all modules and so this method always succeeds when D is in an unnamed or open module.
  
  This method may be used by JNI code with no caller class on the stack to enable access to a member of declaring class D if and only if:
  
  The member is public and D is public in a package that the module containing D exports unconditionally.
  
  This method cannot be used to enable access to private members, members with default (package) access, protected instance members, or protected constructors when the declaring class is in a different module to the caller and the package containing the declaring class is not open to the caller's module.
  
  This method cannot be used to enable write access to a non-modifiable final field. The following fields are non-modifiable:
  
  static final fields declared in any class or interface
  
  final fields declared in a hidden class
  
  final fields declared in a record
  
  The accessible flag when true suppresses Java language access control checks to only enable read access to these non-modifiable final fields.
  If there is a security manager, its checkPermission method is first called with a ReflectPermission("suppressAccessChecks") permission.
  
  Overrides:
  
  setAccessible in class AccessibleObject
  
  Parameters:
  
  flag - the new value for the accessible flag
  
  Throws:
  
  InaccessibleObjectException - if access cannot be enabled
  
  SecurityException - if the request is denied by the security manager
  
  External Specifications
  
  Java Native Interface Specification
  
  See Also:
  
  AccessibleObject.trySetAccessible()
  
  MethodHandles.privateLookupIn(java.lang.Class<?>, java.lang.invoke.MethodHandles.Lookup)
- getDeclaringClass
  
  public Class<?> getDeclaringClass()
  
  Returns the Class object representing the class or interface that declares the method represented by this object.
  
  Specified by:
  
  getDeclaringClass in interface Member
  
  Specified by:
  
  getDeclaringClass in class Executable
  
  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
  
  Specified by:
  
  getName in class Executable
  
  Returns:
  
  the simple name of the underlying member
- getModifiers
  public int getModifiers()
  
  Returns the Java language modifiers for the executable represented by this object.
  
  Specified by:
  
  getModifiers in interface Member
  
  Specified by:
  
  getModifiers in class Executable
  
  Returns:
  
  the Java language modifiers for the executable represented by this object
  
  See Java Language Specification:
  
  8.4.3 Method Modifiers
  
  See Also:
  
  Executable.accessFlags()
- 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
  
  Specified by:
  
  getTypeParameters in class Executable
  
  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
  
  See Java Language Specification:
  
  8.4.4 Generic Methods
  
  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 arguments 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 class or interface declaration
  
  MalformedParameterizedTypeException - if the underlying method's return type 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 executable represented by this object. Returns an array of length 0 if the underlying executable takes no parameters. Note that the constructors of some inner classes may have an implicitly declared parameter in addition to explicitly declared ones.
  
  Specified by:
  
  getParameterTypes in class Executable
  
  Returns:
  
  the parameter types for the executable this object represents
- getParameterCount
  
  public int getParameterCount()
  
  Returns the number of formal parameters (whether explicitly declared or implicitly declared or neither) for the executable represented by this object.
  
  Specified by:
  
  getParameterCount in class Executable
  
  Returns:
  
  The number of formal parameters for the executable this object represents
  
  Since:
  
  1.8
- getGenericParameterTypes
  
  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. An array of length 0 is returned if the underlying executable takes no parameters. Note that the constructors of some inner classes may have an implicitly declared parameter in addition to explicitly declared ones. Also note that as a modeling artifact, the number of returned parameters can differ depending on whether or not generic information is present. If generic information is present, only parameters explicitly present in the source will be returned; if generic information is not present, implicit and synthetic parameters may be returned as well.
  If a formal parameter type is a parameterized type, the Type object returned for it must accurately reflect the actual type arguments 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.
  
  Overrides:
  
  getGenericParameterTypes in class Executable
  
  Returns:
  
  an array of Types that represent the formal parameter types of the underlying executable, in declaration order
  
  Throws:
  
  GenericSignatureFormatError - if the generic method signature does not conform to the format specified in The Java Virtual Machine Specification
  
  TypeNotPresentException - if any of the parameter types of the underlying executable refers to a non-existent type declaration
  
  MalformedParameterizedTypeException - if any of the underlying executable'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 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.
  
  Specified by:
  
  getExceptionTypes in class Executable
  
  Returns:
  
  the exception types declared as being thrown by the executable this object represents
- getGenericExceptionTypes
  
  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.
  
  Overrides:
  
  getGenericExceptionTypes in class Executable
  
  Returns:
  
  an array of Types that represent the exception types thrown by the underlying executable
  
  Throws:
  
  GenericSignatureFormatError - if the generic method signature does not conform to the format specified in The Java Virtual Machine Specification
  
  TypeNotPresentException - if the underlying executable's throws clause refers to a non-existent type declaration
  
  MalformedParameterizedTypeException - if the underlying executable'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()
  
  HashMap
- 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)
  
  System.identityHashCode(java.lang.Object)
- 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, default, static, final, synchronized, native, strictfp.
  
  Overrides:
  
  toString in class Object
  
  Returns:
  
  a string describing this Method
  
  See Java Language Specification:
  
  8.4.3 Method Modifiers
  9.4 Method Declarations
  9.6.1 Annotation Interface Elements
- 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, including informative bounds of the 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.
  
  Specified by:
  
  toGenericString in class Executable
  
  Returns:
  
  a string describing this Method, include type parameters
  
  See Java Language Specification:
  
  8.4.3 Method Modifiers
  9.4 Method Declarations
  9.6.1 Annotation Interface Elements
  
  Since:
  
  1.5
- invoke
  
  public Object invoke(Object obj, Object... args) throws IllegalAccessException, 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, section 15.12.4.4; in particular, overriding based on the runtime type of the target object may 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 parameters args
  
  Throws:
  
  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.
- isBridge
  public boolean isBridge()
  
  Returns true if this method is a bridge method; returns false otherwise.
  
  API Note:
  
  A bridge method is a synthetic method created by a Java compiler alongside a method originating from the source code. Bridge methods are used by Java compilers in various circumstances to span differences in Java programming language semantics and JVM semantics.
  One example use of bridge methods is as a technique for a Java compiler to support covariant overrides, where a subclass overrides a method and gives the new method a more specific return type than the method in the superclass. While the Java language specification forbids a class declaring two methods with the same parameter types but a different return type, the virtual machine does not. A common case where covariant overrides are used is for a Cloneable class where the clone method inherited from java.lang.Object is overridden and declared to return the type of the class. For example, Object declares
  protected Object clone() throws CloneNotSupportedException {...}
  and EnumSet<E> declares its language-level covariant override
  public EnumSet<E> clone() {...}
  If this technique was being used, the resulting class file for EnumSet would have two clone methods, one returning EnumSet<E> and the second a bridge method returning Object. The bridge method is a JVM-level override of Object.clone(). The body of the clone bridge method calls its non-bridge counterpart and returns its result.
  
  Returns:
  
  true if this method is a bridge method; returns false otherwise
  
  See Java Language Specification:
  
  8.4.8.3 Requirements in Overriding and Hiding
  15.12.4.5 Create Frame, Synchronize, Transfer Control
  See Java Virtual Machine Specification:
  
  4.6 Methods
  
  Since:
  
  1.5
  
  See Also:
  
  Java programming language and JVM modeling in core reflection
- isVarArgs
  
  public boolean isVarArgs()
  
  Returns true if this executable was declared to take a variable number of arguments; returns false otherwise.
  
  Overrides:
  
  isVarArgs in class Executable
  
  Returns:
  
  true if this executable was declared to take a variable number of arguments; returns false otherwise
  
  See Java Language Specification:
  
  8.4.1 Formal Parameters
  
  Since:
  
  1.5
- isSynthetic
  public boolean isSynthetic()
  
  Returns true if this executable is a synthetic construct; returns false otherwise.
  
  Specified by:
  
  isSynthetic in interface Member
  
  Overrides:
  
  isSynthetic in class Executable
  
  Returns:
  
  true if and only if this executable is a synthetic construct as defined by The Java Language Specification.
  
  See Java Language Specification:
  
  13.1 The Form of a Binary
  See Java Virtual Machine Specification:
  
  4.6 Methods
  
  Since:
  
  1.5
  
  See Also:
  
  Java programming language and JVM modeling in core reflection
- isDefault
  
  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.
  
  Returns:
  
  true if and only if this method is a default method as defined by the Java Language Specification.
  
  See Java Language Specification:
  
  9.4 Method Declarations
  
  Since:
  
  1.8
- 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.
  
  See Java Language Specification:
  
  9.6.2 Defaults for Annotation Type Elements
  
  Since:
  
  1.5
- getAnnotation
  
  public <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.
  Note that any annotation returned by this method is a declaration annotation.
  
  Specified by:
  
  getAnnotation in interface AnnotatedElement
  
  Overrides:
  
  getAnnotation in class Executable
  
  Type Parameters:
  
  T - the type of the annotation to query for and return if present
  
  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()
  
  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.
  Note that any annotations returned by this method are declaration annotations.
  
  Specified by:
  
  getDeclaredAnnotations in interface AnnotatedElement
  
  Overrides:
  
  getDeclaredAnnotations in class AccessibleObject
  
  Returns:
  
  annotations directly present on this element
  
  Since:
  
  1.5
- getParameterAnnotations
  public Annotation[][] getParameterAnnotations()
  
  Returns an array of arrays of Annotations 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.
  Note that any annotations returned by this method are declaration annotations.
  
  Specified by:
  
  getParameterAnnotations in class Executable
  
  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
  
  Since:
  
  1.5
  
  See Also:
  
  Parameter
  
  Parameter.getAnnotations()
- getAnnotatedReturnType
  
  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.
  
  Specified by:
  
  getAnnotatedReturnType in class Executable
  
  Returns:
  
  an object representing the return type of the method or constructor represented by this Executable
  
  Since:
  
  1.8

Class Method

Field Summary

Fields declared in interface java.lang.reflect.Member

Method Summary

Methods declared in class java.lang.reflect.Executable

Methods declared in class java.lang.reflect.AccessibleObject

Methods declared in class java.lang.Object

Methods declared in interface java.lang.reflect.AnnotatedElement

Method Details

setAccessible

getDeclaringClass

getName

getModifiers

getTypeParameters

getReturnType

getGenericReturnType

getParameterTypes

getParameterCount

getGenericParameterTypes

getExceptionTypes

getGenericExceptionTypes

equals

hashCode

toString

toGenericString

invoke

isBridge

isVarArgs

isSynthetic

isDefault

getDefaultValue

getAnnotation

getDeclaredAnnotations

getParameterAnnotations

getAnnotatedReturnType