Method (Java Platform SE 7 ) (original) (raw)
- 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[])
Field Summary
* ### Fields inherited from interface java.lang.reflect.[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect") `[DECLARED](../../../java/lang/reflect/Member.html#DECLARED), [PUBLIC](../../../java/lang/reflect/Member.html#PUBLIC)`Method Summary
Methods
Modifier and Type Method and Description boolean equals(Object obj) Compares this Method against the specified object. <T extends Annotation> T getAnnotation(Class 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 thisGenericDeclaration 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. * ### Methods inherited from class java.lang.reflect.[AccessibleObject](../../../java/lang/reflect/AccessibleObject.html "class in java.lang.reflect") `[getAnnotations](../../../java/lang/reflect/AccessibleObject.html#getAnnotations%28%29), [isAccessible](../../../java/lang/reflect/AccessibleObject.html#isAccessible%28%29), [isAnnotationPresent](../../../java/lang/reflect/AccessibleObject.html#isAnnotationPresent%28java.lang.Class%29), [setAccessible](../../../java/lang/reflect/AccessibleObject.html#setAccessible%28java.lang.reflect.AccessibleObject[],%20boolean%29), [setAccessible](../../../java/lang/reflect/AccessibleObject.html#setAccessible%28boolean%29)` * ### Methods inherited from class java.lang.[Object](../../../java/lang/Object.html "class in java.lang") `[clone](../../../java/lang/Object.html#clone%28%29), [finalize](../../../java/lang/Object.html#finalize%28%29), [getClass](../../../java/lang/Object.html#getClass%28%29), [notify](../../../java/lang/Object.html#notify%28%29), [notifyAll](../../../java/lang/Object.html#notifyAll%28%29), [wait](../../../java/lang/Object.html#wait%28%29), [wait](../../../java/lang/Object.html#wait%28long%29), [wait](../../../java/lang/Object.html#wait%28long,%20int%29)`Method Detail
* #### getDeclaringClass public [Class](../../../java/lang/Class.html "class in java.lang")<?> getDeclaringClass() Returns the `Class` object representing the class or interface that declares the method represented by this `Method` object. **Specified by:** `[getDeclaringClass](../../../java/lang/reflect/Member.html#getDeclaringClass%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")` Returns: an object representing the declaring class of the underlying member * #### getName public [String](../../../java/lang/String.html "class in java.lang") getName() Returns the name of the method represented by this `Method` object, as a `String`. **Specified by:** `[getName](../../../java/lang/reflect/Member.html#getName%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")` 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](../../../java/lang/reflect/Member.html#getModifiers%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")` Returns: the Java language modifiers for the underlying member See Also: [Modifier](../../../java/lang/reflect/Modifier.html "class in java.lang.reflect") * #### getTypeParameters public [TypeVariable](../../../java/lang/reflect/TypeVariable.html "interface in java.lang.reflect")<[Method](../../../java/lang/reflect/Method.html "class in java.lang.reflect")>[] 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](../../../java/lang/reflect/GenericDeclaration.html#getTypeParameters%28%29)` in interface `[GenericDeclaration](../../../java/lang/reflect/GenericDeclaration.html "interface in java.lang.reflect")` Returns: an array of `TypeVariable` objects that represent the type variables declared by this generic declaration Throws: `[GenericSignatureFormatError](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic signature of this generic declaration does not conform to the format specified inThe Java™ Virtual Machine Specification Since: 1.5 * #### getReturnType public [Class](../../../java/lang/Class.html "class in java.lang")<?> 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](../../../java/lang/reflect/Type.html "interface in java.lang.reflect") 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](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic method signature does not conform to the format specified inThe Java™ Virtual Machine Specification `[TypeNotPresentException](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if the underlying method's return type refers to a non-existent type declaration `[MalformedParameterizedTypeException](../../../java/lang/reflect/MalformedParameterizedTypeException.html "class in java.lang.reflect")` \- 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](../../../java/lang/Class.html "class in java.lang")<?>[] 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](../../../java/lang/reflect/Type.html "interface in java.lang.reflect")[] 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](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic method signature does not conform to the format specified inThe Java™ Virtual Machine Specification `[TypeNotPresentException](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if any of the parameter types of the underlying method refers to a non-existent type declaration `[MalformedParameterizedTypeException](../../../java/lang/reflect/MalformedParameterizedTypeException.html "class in java.lang.reflect")` \- 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](../../../java/lang/Class.html "class in java.lang")<?>[] 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](../../../java/lang/reflect/Type.html "interface in java.lang.reflect")[] 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 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](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic method signature does not conform to the format specified inThe Java™ Virtual Machine Specification `[TypeNotPresentException](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if the underlying method's`throws` clause refers to a non-existent type declaration `[MalformedParameterizedTypeException](../../../java/lang/reflect/MalformedParameterizedTypeException.html "class in java.lang.reflect")` \- 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](../../../java/lang/Object.html "class in java.lang") 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](../../../java/lang/Object.html#equals%28java.lang.Object%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")` 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()](../../../java/lang/Object.html#hashCode%28%29), [HashMap](../../../java/util/HashMap.html "class in java.util") * #### 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](../../../java/lang/Object.html#hashCode%28%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")` Returns: a hash code value for this object. See Also: [Object.equals(java.lang.Object)](../../../java/lang/Object.html#equals%28java.lang.Object%29), [System.identityHashCode(java.lang.Object)](../../../java/lang/System.html#identityHashCode%28java.lang.Object%29) * #### toString public [String](../../../java/lang/String.html "class in java.lang") 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`, `strictfp`. **Overrides:** `[toString](../../../java/lang/Object.html#toString%28%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")` Returns: a string representation of the object. * #### toGenericString public [String](../../../java/lang/String.html "class in java.lang") 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. 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`, `strictfp`. Returns: a string describing this `Method`, include type parameters Since: 1.5 * #### invoke public [Object](../../../java/lang/Object.html "class in java.lang") invoke([Object](../../../java/lang/Object.html "class in java.lang") obj, [Object](../../../java/lang/Object.html "class in java.lang")... args) throws [IllegalAccessException](../../../java/lang/IllegalAccessException.html "class in java.lang"), [IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang"), [InvocationTargetException](../../../java/lang/reflect/InvocationTargetException.html "class in java.lang.reflect") 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 parameters`args` Throws: `[IllegalAccessException](../../../java/lang/IllegalAccessException.html "class in java.lang")` \- if this `Method` object is enforcing Java language access control and the underlying method is inaccessible. `[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang")` \- 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](../../../java/lang/reflect/InvocationTargetException.html "class in java.lang.reflect")` \- if the underlying method throws an exception. `[NullPointerException](../../../java/lang/NullPointerException.html "class in java.lang")` \- if the specified object is null and the method is an instance method. `[ExceptionInInitializerError](../../../java/lang/ExceptionInInitializerError.html "class in java.lang")` \- 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](../../../java/lang/reflect/Member.html#isSynthetic%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")` 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](../../../java/lang/annotation/Annotation.html "interface in java.lang.annotation")> T getAnnotation([Class](../../../java/lang/Class.html "class in java.lang")<T> annotationClass) Returns this element's annotation for the specified type if such an annotation is present, else null. **Specified by:** `[getAnnotation](../../../java/lang/reflect/AnnotatedElement.html#getAnnotation%28java.lang.Class%29)` in interface `[AnnotatedElement](../../../java/lang/reflect/AnnotatedElement.html "interface in java.lang.reflect")` **Overrides:** `[getAnnotation](../../../java/lang/reflect/AccessibleObject.html#getAnnotation%28java.lang.Class%29)` in class `[AccessibleObject](../../../java/lang/reflect/AccessibleObject.html "class in java.lang.reflect")` 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](../../../java/lang/NullPointerException.html "class in java.lang")` \- if the given annotation class is null Since: 1.5 * #### getDeclaredAnnotations public [Annotation](../../../java/lang/annotation/Annotation.html "interface in java.lang.annotation")[] getDeclaredAnnotations() 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](../../../java/lang/reflect/AnnotatedElement.html#getDeclaredAnnotations%28%29)` in interface `[AnnotatedElement](../../../java/lang/reflect/AnnotatedElement.html "interface in java.lang.reflect")` **Overrides:** `[getDeclaredAnnotations](../../../java/lang/reflect/AccessibleObject.html#getDeclaredAnnotations%28%29)` in class `[AccessibleObject](../../../java/lang/reflect/AccessibleObject.html "class in java.lang.reflect")` Returns: All annotations directly present on this element Since: 1.5 * #### getDefaultValue public [Object](../../../java/lang/Object.html "class in java.lang") 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](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if the annotation is of type[Class](../../../java/lang/Class.html "class in java.lang") and no definition can be found for the default class value. Since: 1.5 * #### getParameterAnnotations public [Annotation](../../../java/lang/annotation/Annotation.html "interface in java.lang.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
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