Skip to content

Most visited

Recently visited

navigation

Method

public final class Method
extends Executable

java.lang.Object
   ↳ java.lang.reflect.AccessibleObject
     ↳ java.lang.reflect.Executable
       ↳ java.lang.reflect.Method


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:

Summary

Inherited constants

From interface java.lang.reflect.Member

Public methods

boolean equals(Object obj)

Compares this Method against the specified object.

<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 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.

String toGenericString()

Returns a string describing this Method, including type parameters.

String toString()

Returns a string describing this Method.

Inherited methods

From class java.lang.reflect.Executable
From class java.lang.reflect.AccessibleObject
From class java.lang.Object
From interface java.lang.reflect.Member
From interface java.lang.reflect.GenericDeclaration
From interface java.lang.reflect.AnnotatedElement

Public methods

equals

added in API level 1
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 Object: the reference object with which to compare.

Returns
boolean true if this object is the same as the obj argument; false otherwise.

getAnnotation

added in API level 1
T getAnnotation (Class<T> annotationClass)

Returns this element's annotation for the specified type if such an annotation is present, else null.

Parameters
annotationClass Class: the Class object corresponding to the annotation type

Returns
T this element's annotation for the specified annotation type if present on this element, else null

Throws
NullPointerException

getDeclaredAnnotations

added in API level 1
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
Annotation[] annotations directly present on this element

getDeclaringClass

added in API level 1
Class<?> getDeclaringClass ()

Returns the Class object representing the class or interface that declares the executable represented by this object.

Returns
Class<?> an object representing the declaring class of the underlying member

getDefaultValue

added in API level 1
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
Object 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.

getExceptionTypes

added in API level 1
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
Class[]<?> the exception types declared as being thrown by the executable this object represents

getGenericExceptionTypes

added in API level 1
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
Type[] an array of Types that represent the exception types thrown by the underlying executable

Throws
GenericSignatureFormatError
TypeNotPresentException
MalformedParameterizedTypeException

getGenericParameterTypes

added in API level 1
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
Type[] an array of Types that represent the formal parameter types of the underlying executable, in declaration order

Throws
GenericSignatureFormatError
TypeNotPresentException
MalformedParameterizedTypeException

getGenericReturnType

added in API level 1
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
Type 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

getModifiers

added in API level 1
int getModifiers ()

Returns the Java language modifiers for the executable represented by this object.

Returns
int the Java language modifiers for the underlying member

getName

added in API level 1
String getName ()

Returns the name of the method represented by this Method object, as a String.

Returns
String the simple name of the underlying member

getParameterAnnotations

added in API level 1
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.

Returns
Annotation[][] an array of arrays that represent the annotations on the formal and implicit parameters, in declaration order, of the executable represented by this object

getParameterCount

added in API level 26
int getParameterCount ()

Returns the number of formal parameters (whether explicitly declared or implicitly declared or neither) for the executable represented by this object.

Returns
int The number of formal parameters for the executable this object represents

getParameterTypes

added in API level 1
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
Class[]<?> the parameter types for the executable this object represents

getReturnType

added in API level 1
Class<?> getReturnType ()

Returns a Class object that represents the formal return type of the method represented by this Method object.

Returns
Class<?> the return type for the method this object represents

getTypeParameters

added in API level 1
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
TypeVariable[]<Method> an array of TypeVariable objects that represent the type variables declared by this generic declaration

Throws
GenericSignatureFormatError

hashCode

added in API level 1
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
int a hash code value for this object.

invoke

added in API level 1
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 Object: the object the underlying method is invoked from

args Object: the arguments used for the method call

Returns
Object 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

added in API level 1
boolean isBridge ()

Returns true if this method is a bridge method; returns false otherwise.

Returns
boolean true if and only if this method is a bridge method as defined by the Java Language Specification.

isDefault

added in API level 24
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
boolean true if and only if this method is a default method as defined by the Java Language Specification.

isSynthetic

added in API level 1
boolean isSynthetic ()

Returns true if this executable is a synthetic construct; returns false otherwise.

Returns
boolean true if and only if this executable is a synthetic construct as defined by The Java™ Language Specification.

isVarArgs

added in API level 1
boolean isVarArgs ()

Returns true if this executable was declared to take a variable number of arguments; returns false otherwise.

Returns
boolean true if an only if this executable was declared to take a variable number of arguments.

toGenericString

added in API level 1
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
String a string describing this Method, include type parameters

toString

added in API level 1
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
String a string describing this Method

This site uses cookies to store your preferences for site-specific language and display options.

Get the latest Android developer news and tips that will help you find success on Google Play.

* Required Fields

Hooray!

Browse this site in ?

You requested a page in , but your language preference for this site is .

Would you like to change your language preference and browse this site in ? If you want to change your language preference later, use the language menu at the bottom of each page.

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a one-minute survey?
Help us improve Android tools and documentation.