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java.lang.Objectjava.lang.reflect.AccessibleObject
java.lang.reflect.Method
public final class Method
The Method class represents a member method of a class. It also allows
dynamic invocation, via reflection. This works for both static and
instance methods. Invocation on Method objects knows how to do
widening conversions, but throws IllegalArgumentException
if
a narrowing conversion would be necessary. You can query for information
on this Method regardless of location, but invocation access may be limited
by Java language access controls. If you can't do it in the compiler, you
can't normally do it here either.
Note: This class returns and accepts types as Classes, even
primitive types; there are Class types defined that represent each
different primitive type. They are java.lang.Boolean.TYPE,
java.lang.Byte.TYPE,
, also available as boolean.class,
byte.class
, etc. These are not to be confused with the
classes java.lang.Boolean, java.lang.Byte
, etc., which are
real classes.
Also note that this is not a serializable class. It is entirely feasible to make it serializable using the Externalizable interface, but this is on Sun, not me.
Member
,
Class
,
Class.getMethod(String,Class[])
,
Class.getDeclaredMethod(String,Class[])
,
Class.getMethods()
,
Class.getDeclaredMethods()
Field Summary |
---|
Fields inherited from interface java.lang.reflect.Member |
---|
DECLARED, PUBLIC |
Method Summary | ||
---|---|---|
boolean |
equals(Object obj)
Compare two objects to see if they are semantically equivalent. |
|
|
getAnnotation(Class<T> annoClass)
Returns the element's annotation for the specified annotation type, or null if no such annotation exists. |
|
Annotation[] |
getDeclaredAnnotations()
Returns all annotations directly defined by the element. |
|
Class<?> |
getDeclaringClass()
Gets the class that declared this method, or the class where this method is a non-inherited member. |
|
Object |
getDefaultValue()
If this method is an annotation method, returns the default value for the method. |
|
Class<?>[] |
getExceptionTypes()
Get the exception types this method says it throws, in no particular order. |
|
Type[] |
getGenericExceptionTypes()
Returns an array of Type objects that represents
the exception types declared by this method, in declaration order. |
|
Type[] |
getGenericParameterTypes()
Returns an array of Type objects that represents
the parameter list for this method, in declaration order. |
|
Type |
getGenericReturnType()
Returns the return type of this method. |
|
int |
getModifiers()
Gets the modifiers this method uses. |
|
String |
getName()
Gets the name of this method. |
|
Annotation[][] |
getParameterAnnotations()
|
|
Class<?>[] |
getParameterTypes()
Get the parameter list for this method, in declaration order. |
|
Class<?> |
getReturnType()
Gets the return type of this method. |
|
TypeVariable<Method>[] |
getTypeParameters()
Returns an array of TypeVariable objects that represents
the type variables declared by this constructor, in declaration order. |
|
int |
hashCode()
Get the hash code for the Method. |
|
Object |
invoke(Object obj,
Object... args)
Invoke the method. |
|
boolean |
isBridge()
Return true if this method is a bridge method. |
|
boolean |
isSynthetic()
Return true if this method is synthetic, false otherwise. |
|
boolean |
isVarArgs()
Return true if this is a varargs method, that is if the method takes a variable number of arguments. |
|
String |
toGenericString()
|
|
String |
toString()
Get a String representation of the Method. |
Methods inherited from class java.lang.reflect.AccessibleObject |
---|
getAnnotations, isAccessible, isAnnotationPresent, setAccessible, setAccessible |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Method Detail |
---|
public Class<?> getDeclaringClass()
getDeclaringClass
in interface Member
public String getName()
getName
in interface Member
public int getModifiers()
Modifier
class to interpret the values. A method can only have a subset of the
following modifiers: public, private, protected, abstract, static,
final, synchronized, native, and strictfp.
getModifiers
in interface Member
Modifier
public boolean isBridge()
public boolean isSynthetic()
isSynthetic
in interface Member
public boolean isVarArgs()
public Class<?> getReturnType()
public Class<?>[] getParameterTypes()
public Class<?>[] getExceptionTypes()
public boolean equals(Object obj)
equals
in class Object
o
- the object to compare to
true
if they are equal; false
if notObject.hashCode()
public int hashCode()
hashCode
in class Object
Object.equals(Object)
,
System.identityHashCode(Object)
public String toString()
public static int run(java.lang.Runnable,int)
toString
in class Object
Object.getClass()
,
Object.hashCode()
,
Class.getName()
,
Integer.toHexString(int)
public String toGenericString()
public Object invoke(Object obj, Object... args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException
If the method is static, o
will be ignored. Otherwise,
the method uses dynamic lookup as described in JLS 15.12.4.4. You cannot
mimic the behavior of nonvirtual lookup (as in super.foo()). This means
you will get a NullPointerException
if o
is
null, and an IllegalArgumentException
if it is incompatible
with the declaring class of the method. If the method takes 0 arguments,
you may use null or a 0-length array for args
.
Next, if this Method enforces access control, your runtime context is
evaluated, and you may have an IllegalAccessException
if
you could not acces this method in similar compiled code. If the method
is static, and its class is uninitialized, you trigger class
initialization, which may end in a
ExceptionInInitializerError
.
Finally, the method is invoked. If it completes normally, the return value
will be null for a void method, a wrapped object for a primitive return
method, or the actual return of an Object method. If it completes
abruptly, the exception is wrapped in an
InvocationTargetException
.
o
- the object to invoke the method onargs
- the arguments to the method
IllegalAccessException
- if the method could not normally be called
by the Java code (i.e. it is not public)
IllegalArgumentException
- if the number of arguments is incorrect;
if the arguments types are wrong even with a widening conversion;
or if o
is not an instance of the class or interface
declaring this method
InvocationTargetException
- if the method throws an exception
NullPointerException
- if o
is null and this field
requires an instance
ExceptionInInitializerError
- if accessing a static method triggered
class initialization, which then failedpublic TypeVariable<Method>[] getTypeParameters()
TypeVariable
objects that represents
the type variables declared by this constructor, in declaration order.
An array of size zero is returned if this class has no type
variables.
getTypeParameters
in interface GenericDeclaration
GenericSignatureFormatError
- if the generic signature does
not conform to the format specified in the Virtual Machine
specification, version 3.public Type[] getGenericExceptionTypes()
Type
objects that represents
the exception types declared by this method, in declaration order.
An array of size zero is returned if this method declares no
exceptions.
GenericSignatureFormatError
- if the generic signature does
not conform to the format specified in the Virtual Machine
specification, version 3.public Type[] getGenericParameterTypes()
Type
objects that represents
the parameter list for this method, in declaration order.
An array of size zero is returned if this method takes no
parameters.
GenericSignatureFormatError
- if the generic signature does
not conform to the format specified in the Virtual Machine
specification, version 3.public Type getGenericReturnType()
GenericSignatureFormatError
- if the generic signature does
not conform to the format specified in the Virtual Machine
specification, version 3.public Object getDefaultValue()
TypeNotPresentException
- if the method returns a Class,
and the class cannot be foundpublic <T extends Annotation> T getAnnotation(Class<T> annoClass)
AccessibleObject
Returns the element's annotation for the specified annotation type,
or null
if no such annotation exists.
This method must be overridden by subclasses to provide appropriate behaviour.
getAnnotation
in interface AnnotatedElement
getAnnotation
in class AccessibleObject
annoClass
- the type of annotation to look for.
null
if no such annotation exists.public Annotation[] getDeclaredAnnotations()
AccessibleObject
Returns all annotations directly defined by the element. If there are no annotations directly associated with the element, then a zero-length array will be returned. The returned array may be modified by the client code, but this will have no effect on the annotation content of this class, and hence no effect on the return value of this method for future callers.
This method must be overridden by subclasses to provide appropriate behaviour.
getDeclaredAnnotations
in interface AnnotatedElement
getDeclaredAnnotations
in class AccessibleObject
public Annotation[][] getParameterAnnotations()
|
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