Instances of the class
Class represent classes and
interfaces in a running Java application. An enum is a kind of
class and an annotation is a kind of interface. Every array also
belongs to a class that is reflected as a
Class object
that is shared by all arrays with the same element type and number
of dimensions. The primitive Java types (
boolean ,
byte ,
char ,
short ,
int ,
long ,
float , and
double ), and the keyword
void are also
represented as
Class objects.
Class has no public constructor. Instead
Class objects are constructed automatically by the Java Virtual Machine as classes
are loaded and by calls to the
defineClass method in the class
loader.
The following example uses a
Class object to print the
class name of an object:
void printClassName(Object obj) {
System.out.println("The class of " + obj +
" is " + obj.getClass().getName());
}
It is also possible to get the
Class object for a named
type (or for void) using a class literal
(JLS Section 15.8.2).
For example:
System.out.println("The name of class Foo is: "+Foo.class.getName());
< Parameters: T - > the type of the class modeled by this Class object. For example, the type of String.class is Class . Use Class if the class being modeled isunknown. author: unascribed version: 1.211, 07/27/07 See Also:java.lang.ClassLoader.defineClass(byte[]intint) since: JDK1.0
asSubclass(Class<U> clazz) Casts this
Class object to represent a subclass of the class
represented by the specified class object.
public T
cast(Object obj) Casts an object to the class or interface represented
by this
Class object.
public boolean
desiredAssertionStatus() Returns the assertion status that would be assigned to this
class if it were to be initialized at the time this method is invoked.
If this class has had its assertion status set, the most recent
setting will be returned; otherwise, if any package default assertion
status pertains to this class, the most recent setting for the most
specific pertinent package default assertion status is returned;
otherwise, if this class is not a system class (i.e., it has a
class loader) its class loader's default assertion status is returned;
otherwise, the system class default assertion status is returned.
Few programmers will have any need for this method; it is provided
for the benefit of the JRE itself.
forName(String name, boolean initialize, ClassLoader loader) Returns the
Class object associated with the class or
interface with the given string name, using the given class loader.
Given the fully qualified name for a class or interface (in the same
format returned by
getName ) this method attempts to
locate, load, and link the class or interface.
getClasses() Returns an array containing
Class objects representing all
the public classes and interfaces that are members of the class
represented by this
Class object.
getConstructor(Class... parameterTypes) Returns a
Constructor object that reflects the specified
public constructor of the class represented by this
Class object.
getConstructors() Returns an array containing
Constructor objects reflecting
all the public constructors of the class represented by this
Class object.
getDeclaredClasses() Returns an array of
Class objects reflecting all the
classes and interfaces declared as members of the class represented by
this
Class object.
getDeclaredConstructor(Class... parameterTypes) Returns a
Constructor object that reflects the specified
constructor of the class or interface represented by this
Class object.
getDeclaredConstructors() Returns an array of
Constructor objects reflecting all the
constructors declared by the class represented by this
Class object.
getDeclaredField(String name) Returns a
Field object that reflects the specified declared
field of the class or interface represented by this
Class object.
getDeclaredMethod(String name, Class... parameterTypes) Returns a
Method object that reflects the specified
declared method of the class or interface represented by this
Class object.
getDeclaredMethods() Returns an array of
Method objects reflecting all the
methods declared by the class or interface represented by this
Class object.
getDeclaringClass() If the class or interface represented by this
Class object
is a member of another class, returns the
Class object
representing the class in which it was declared.
getEnclosingConstructor() If this
Class object represents a local or anonymous
class within a constructor, returns a
java.lang.reflect.Constructor Constructor object representing
the immediately enclosing constructor of the underlying
class.
getEnclosingMethod() If this
Class object represents a local or anonymous
class within a method, returns a
java.lang.reflect.Method Method object representing the
immediately enclosing method of the underlying class.
public T[]
getEnumConstants() Returns the elements of this enum class or null if this
Class object does not represent an enum type.
T[]
getEnumConstantsShared() Returns the elements of this enum class or null if this
Class object does not represent an enum type;
identical to getEnumConstantsShared except that
the result is uncloned, cached, and shared by all callers.
getField(String name) Returns a
Field object that reflects the specified public
member field of the class or interface represented by this
Class object.
getFields() Returns an array containing
Field objects reflecting all
the accessible public fields of the class or interface represented by
this
Class object.
getGenericInterfaces() Returns the
Type s representing the interfaces
directly implemented by the class or interface represented by
this object.
If a superinterface is a parameterized type, the
Type object returned for it must accurately reflect
the actual type parameters used in the source code.
getGenericSuperclass() Returns the
Type representing the direct superclass of
the entity (class, interface, primitive type or void) represented by
this
Class .
If the superclass is a parameterized type, the
Type object returned must accurately reflect the actual type
parameters used in the source code.
getMethod(String name, Class... parameterTypes) Returns a
Method object that reflects the specified public
member method of the class or interface represented by this
Class object.
getMethods() Returns an array containing
Method objects reflecting all
the public member methods of the class or interface represented
by this
Class object, including those declared by the class
or interface and those inherited from superclasses and
superinterfaces.
native public int
getModifiers() Returns the Java language modifiers for this class or interface, encoded
in an integer.
getName() Returns the name of the entity (class, interface, array class,
primitive type, or void) represented by this
Class object,
as a
String .
If this class object represents a reference type that is not an
array type then the binary name of the class is returned, as specified
by the Java Language Specification, Second Edition.
If this class object represents a primitive type or void, then the
name returned is a
String equal to the Java language
keyword corresponding to the primitive type or void.
If this class object represents a class of arrays, then the internal
form of the name consists of the name of the element type preceded by
one or more '
[ ' characters representing the depth of the array
nesting.
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.
public boolean
isAnnotation() Returns true if this
Class object represents an annotation
type.
isAnonymousClass() Returns
true if and only if the underlying class
is an anonymous class.
native public boolean
isArray() Determines if this
Class object represents an array class.
native public boolean
isAssignableFrom(Class cls) Determines if the class or interface represented by this
Class object is either the same as, or is a superclass or
superinterface of, the class or interface represented by the specified
Class parameter.
public boolean
isEnum() Returns true if and only if this class was declared as an enum in the
source code.
native public boolean
isInstance(Object obj) Determines if the specified
Object is assignment-compatible
with the object represented by this
Class .
native public boolean
isInterface() Determines if the specified
Class object represents an
interface type.
public boolean
isLocalClass() Returns
true if and only if the underlying class
is a local class.
public boolean
isMemberClass() Returns
true if and only if the underlying class
is a member class.
native public boolean
isPrimitive() Determines if the specified
Class object represents a
primitive type.
There are nine predefined
Class objects to represent
the eight primitive types and void.
public boolean
isSynthetic() Returns
true if this class is a synthetic class;
returns
false otherwise.
public T
newInstance() Creates a new instance of the class represented by this
Class object.
Casts this
Class object to represent a subclass of the class
represented by the specified class object. Checks that that the cast
is valid, and throws a
ClassCastException if it is not. If
this method succeeds, it always returns a reference to this class object.
This method is useful when a client needs to "narrow" the type of
a
Class object to pass it to an API that restricts the
Class objects that it is willing to accept. A cast would
generate a compile-time warning, as the correctness of the cast
could not be checked at runtime (because generic types are implemented
by erasure).
this Class object, cast to represent a subclass ofthe specified class object. throws: ClassCastException - if this Class object does notrepresent a subclass of the specified class (here "subclass" includesthe class itself). since: 1.5
Casts an object to the class or interface represented
by this
Class object.
Parameters: obj - the object to be cast the object after casting, or null if obj is null throws: ClassCastException - if the object is notnull and is not assignable to the type T. since: 1.5
Returns the assertion status that would be assigned to this
class if it were to be initialized at the time this method is invoked.
If this class has had its assertion status set, the most recent
setting will be returned; otherwise, if any package default assertion
status pertains to this class, the most recent setting for the most
specific pertinent package default assertion status is returned;
otherwise, if this class is not a system class (i.e., it has a
class loader) its class loader's default assertion status is returned;
otherwise, the system class default assertion status is returned.
Few programmers will have any need for this method; it is provided
for the benefit of the JRE itself. (It allows a class to determine at
the time that it is initialized whether assertions should be enabled.)
Note that this method is not guaranteed to return the actual
assertion status that was (or will be) associated with the specified
class when it was (or will be) initialized.
the desired assertion status of the specified class. See Also:java.lang.ClassLoader.setClassAssertionStatus See Also:java.lang.ClassLoader.setPackageAssertionStatus See Also:java.lang.ClassLoader.setDefaultAssertionStatus since: 1.4
Returns a map from simple name to enum constant. This package-private
method is used internally by Enum to implement
public static > T valueOf(Class, String)
efficiently. Note that the map is returned by this method is
created lazily on first use. Typically it won't ever get created.
Returns the
Class object associated with the class or
interface with the given string name. Invoking this method is
equivalent to:
Class.forName(className, true, currentLoader)
where
currentLoader denotes the defining class loader of
the current class.
For example, the following code fragment returns the
runtime
Class descriptor for the class named
java.lang.Thread :
Class t = Class.forName("java.lang.Thread")
A call to
forName("X") causes the class named
X to be initialized.
Parameters: className - the fully qualified name of the desired class. the Class object for the class with thespecified name. exception: LinkageError - if the linkage fails exception: ExceptionInInitializerError - if the initialization provokedby this method fails exception: ClassNotFoundException - if the class cannot be located
Returns the
Class object associated with the class or
interface with the given string name, using the given class loader.
Given the fully qualified name for a class or interface (in the same
format returned by
getName ) this method attempts to
locate, load, and link the class or interface. The specified class
loader is used to load the class or interface. If the parameter
loader is null, the class is loaded through the bootstrap
class loader. The class is initialized only if the
initialize parameter is
true and if it has
not been initialized earlier.
If
name denotes a primitive type or void, an attempt
will be made to locate a user-defined class in the unnamed package whose
name is
name . Therefore, this method cannot be used to
obtain any of the
Class objects representing primitive
types or void.
If
name denotes an array class, the component type of
the array class is loaded but not initialized.
For example, in an instance method the expression:
Note that this method throws errors related to loading, linking or
initializing as specified in Sections 12.2, 12.3 and 12.4 of The
Java Language Specification.
Note that this method does not check whether the requested class
is accessible to its caller.
If the
loader is
null , and a security
manager is present, and the caller's class loader is not null, then this
method calls the security manager's
checkPermission method
with a
RuntimePermission("getClassLoader") permission to
ensure it's ok to access the bootstrap class loader.
Parameters: name - fully qualified name of the desired class Parameters: initialize - whether the class must be initialized Parameters: loader - class loader from which the class must be loaded class object representing the desired class exception: LinkageError - if the linkage fails exception: ExceptionInInitializerError - if the initialization provokedby this method fails exception: ClassNotFoundException - if the class cannot be located bythe specified class loader See Also:java.lang.Class.forName(String) See Also: See Also:java.lang.ClassLoader since: 1.2
getAnnotation
public A getAnnotation(Class<A> annotationClass)(Code)
Returns the canonical name of the underlying class as
defined by the Java Language Specification. Returns null if
the underlying class does not have a canonical name (i.e., if
it is a local or anonymous class or an array whose component
type does not have a canonical name).
the canonical name of the underlying class if it exists, and null otherwise. since: 1.5
Returns the class loader for the class. Some implementations may use
null to represent the bootstrap class loader. This method will return
null in such implementations if this class was loaded by the bootstrap
class loader.
If a security manager is present, and the caller's class loader is
not null and the caller's class loader is not the same as or an ancestor of
the class loader for the class whose class loader is requested, then
this method calls the security manager's
checkPermission
method with a
RuntimePermission("getClassLoader")
permission to ensure it's ok to access the class loader for the class.
If this object
represents a primitive type or void, null is returned.
the class loader that loaded the class or interfacerepresented by this object. throws: SecurityException - if a security manager exists and its checkPermission method deniesaccess to the class loader for the class. See Also:java.lang.ClassLoader See Also:SecurityManager.checkPermission See Also:java.lang.RuntimePermission
Returns an array containing
Class objects representing all
the public classes and interfaces that are members of the class
represented by this
Class object. This includes public
class and interface members inherited from superclasses and public class
and interface members declared by the class. This method returns an
array of length 0 if this
Class object has no public member
classes or interfaces. This method also returns an array of length 0 if
this
Class object represents a primitive type, an array
class, or void.
the array of Class objects representing the publicmembers of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.PUBLIC) methoddenies access to the classes within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the package of this class
Returns the
Class representing the component type of an
array. If this class does not represent an array class this method
returns null.
the Class representing the component type of thisclass if this class is an array See Also:java.lang.reflect.Array since: JDK1.1
Returns a
Constructor object that reflects the specified
public constructor of the class represented by this
Class object. The
parameterTypes parameter is an array of
Class objects that identify the constructor's formal
parameter types, in declared order.
If this
Class object represents an inner class
declared in a non-static context, the formal parameter types
include the explicit enclosing instance as the first parameter.
The constructor to reflect is the public constructor of the class
represented by this
Class object whose formal parameter
types match those specified by
parameterTypes .
Parameters: parameterTypes - the parameter array the Constructor object of the public constructor thatmatches the specified parameterTypes exception: NoSuchMethodException - if a matching method is not found. exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array containing
Constructor objects reflecting
all the public constructors of the class represented by this
Class object. An array of length 0 is returned if the
class has no public constructors, or if the class is an array class, or
if the class reflects a primitive type or void.
Note that while this method returns an array of
Constructor objects (that is an array of constructors from
this class), the return type of this method is
Constructor[] and not
Constructor[] as
might be expected. This less informative return type is
necessary since after being returned from this method, the
array could be modified to hold
Constructor objects for
different classes, which would violate the type guarantees of
Constructor[] .
the array of Constructor objects representing thepublic constructors of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.PUBLIC) deniesaccess to the constructors within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array of
Class objects reflecting all the
classes and interfaces declared as members of the class represented by
this
Class object. This includes public, protected, default
(package) access, and private classes and interfaces declared by the
class, but excludes inherited classes and interfaces. This method
returns an array of length 0 if the class declares no classes or
interfaces as members, or if this
Class object represents a
primitive type, an array class, or void.
the array of Class objects representing all the declared members of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.DECLARED) deniesaccess to the declared classes within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns a
Constructor object that reflects the specified
constructor of the class or interface represented by this
Class object. The
parameterTypes parameter is
an array of
Class objects that identify the constructor's
formal parameter types, in declared order.
If this
Class object represents an inner class
declared in a non-static context, the formal parameter types
include the explicit enclosing instance as the first parameter.
Parameters: parameterTypes - the parameter array The Constructor object for the constructor with thespecified parameter list exception: NoSuchMethodException - if a matching method is not found. exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array of
Constructor objects reflecting all the
constructors declared by the class represented by this
Class object. These are public, protected, default
(package) access, and private constructors. The elements in the array
returned are not sorted and are not in any particular order. If the
class has a default constructor, it is included in the returned array.
This method returns an array of length 0 if this
Class object represents an interface, a primitive type, an array class, or
void.
See The Java Language Specification, section 8.2.
the array of Constructor objects representing all thedeclared constructors of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.DECLARED) deniesaccess to the declared constructors within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns a
Field object that reflects the specified declared
field of the class or interface represented by this
Class object. The
name parameter is a
String that
specifies the simple name of the desired field. Note that this method
will not reflect the
length field of an array class.
Parameters: name - the name of the field the Field object for the specified field in thisclass exception: NoSuchFieldException - if a field with the specified name isnot found. exception: NullPointerException - if name is null exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array of
Field objects reflecting all the fields
declared by the class or interface represented by this
Class object. This includes public, protected, default
(package) access, and private fields, but excludes inherited fields.
The elements in the array returned are not sorted and are not in any
particular order. This method returns an array of length 0 if the class
or interface declares no fields, or if this
Class object
represents a primitive type, an array class, or void.
See The Java Language Specification, sections 8.2 and 8.3.
the array of Field objects representing all thedeclared fields of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.DECLARED) deniesaccess to the declared fields within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns a
Method object that reflects the specified
declared method of the class or interface represented by this
Class object. The
name parameter is a
String that specifies the simple name of the desired
method, and the
parameterTypes parameter is an array of
Class objects that identify the method's formal parameter
types, in declared order. If more than one method with the same
parameter types is declared in a class, and one of these methods has a
return type that is more specific than any of the others, that method is
returned; otherwise one of the methods is chosen arbitrarily. If the
name is "<init>"or "<clinit>" a
NoSuchMethodException is raised.
Parameters: name - the name of the method Parameters: parameterTypes - the parameter array the Method object for the method of this classmatching the specified name and parameters exception: NoSuchMethodException - if a matching method is not found. exception: NullPointerException - if name is null exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array of
Method objects reflecting all the
methods declared by the class or interface represented by this
Class object. This includes public, protected, default
(package) access, and private methods, but excludes inherited methods.
The elements in the array returned are not sorted and are not in any
particular order. This method returns an array of length 0 if the class
or interface declares no methods, or if this
Class object
represents a primitive type, an array class, or void. The class
initialization method
is not included in the
returned array. If the class declares multiple public member methods
with the same parameter types, they are all included in the returned
array.
See The Java Language Specification, section 8.2.
the array of Method objects representing all thedeclared methods of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.DECLARED) deniesaccess to the declared methods within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
If the class or interface represented by this
Class object
is a member of another class, returns the
Class object
representing the class in which it was declared. This method returns
null if this class or interface is not a member of any other class. If
this
Class object represents an array class, a primitive
type, or void,then this method returns null.
the declaring class for this class since: JDK1.1
Returns the immediately enclosing class of the underlying
class. If the underlying class is a top level class this
method returns
null .
the immediately enclosing class of the underlying class since: 1.5
If this
Class object represents a local or anonymous
class within a constructor, returns a
java.lang.reflect.Constructor Constructor object representing
the immediately enclosing constructor of the underlying
class. Returns
null otherwise. In particular, this
method returns
null if the underlying class is a local
or anonymous class immediately enclosed by a type declaration,
instance initializer or static initializer.
the immediately enclosing constructor of the underlying class, ifthat class is a local or anonymous class; otherwise null . since: 1.5
If this
Class object represents a local or anonymous
class within a method, returns a
java.lang.reflect.Method Method object representing the
immediately enclosing method of the underlying class. Returns
null otherwise.
In particular, this method returns
null if the underlying
class is a local or anonymous class immediately enclosed by a type
declaration, instance initializer or static initializer.
the immediately enclosing method of the underlying class, ifthat class is a local or anonymous class; otherwise null . since: 1.5
Returns the elements of this enum class or null if this
Class object does not represent an enum type.
an array containing the values comprising the enum classrepresented by this Class object in the order they'redeclared, or null if this Class object does notrepresent an enum type since: 1.5
Returns the elements of this enum class or null if this
Class object does not represent an enum type;
identical to getEnumConstantsShared except that
the result is uncloned, cached, and shared by all callers.
Returns a
Field object that reflects the specified public
member field of the class or interface represented by this
Class object. The
name parameter is a
String specifying the simple name of the desired field.
The field to be reflected is determined by the algorithm that
follows. Let C be the class represented by this object:
If C declares a public field with the name specified, that is the
field to be reflected.
If no field was found in step 1 above, this algorithm is applied
recursively to each direct superinterface of C. The direct
superinterfaces are searched in the order they were declared.
If no field was found in steps 1 and 2 above, and C has a
superclass S, then this algorithm is invoked recursively upon S.
If C has no superclass, then a
NoSuchFieldException is thrown.
See The Java Language Specification, sections 8.2 and 8.3.
Parameters: name - the field name the Field object of this class specified by name exception: NoSuchFieldException - if a field with the specified name isnot found. exception: NullPointerException - if name is null exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array containing
Field objects reflecting all
the accessible public fields of the class or interface represented by
this
Class object. The elements in the array returned are
not sorted and are not in any particular order. This method returns an
array of length 0 if the class or interface has no accessible public
fields, or if it represents an array class, a primitive type, or void.
Specifically, if this
Class object represents a class,
this method returns the public fields of this class and of all its
superclasses. If this
Class object represents an
interface, this method returns the fields of this interface and of all
its superinterfaces.
The implicit length field for array class is not reflected by this
method. User code should use the methods of class
Array to
manipulate arrays.
See The Java Language Specification, sections 8.2 and 8.3.
the array of Field objects representing thepublic fields exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.PUBLIC) deniesaccess to the fields within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns the
Type s representing the interfaces
directly implemented by the class or interface represented by
this object.
If a superinterface is a parameterized type, the
Type object returned for it must accurately reflect
the actual type parameters used in the source code. The
parameterized type representing each superinterface is created
if it had not been created before. See the declaration of
java.lang.reflect.ParameterizedType ParameterizedType for the semantics of the creation process for parameterized
types.
If this object represents a class, the return value is an
array containing objects representing all interfaces
implemented by the class. The order of the interface objects in
the array corresponds to the order of the interface names in
the
implements clause of the declaration of the class
represented by this object. In the case of an array class, the
interfaces
Cloneable and
Serializable are
returned in that order.
If this object represents an interface, the array contains
objects representing all interfaces directly extended by the
interface. The order of the interface objects in the array
corresponds to the order of the interface names in the
extends clause of the declaration of the interface
represented by this object.
If this object represents a class or interface that
implements no interfaces, the method returns an array of length
0.
If this object represents a primitive type or void, the
method returns an array of length 0.
throws: GenericSignatureFormatError - if the generic class signature does not conform to the formatspecified in the Java Virtual Machine Specification, 3rd edition throws: TypeNotPresentException - if any of the genericsuperinterfaces refers to a non-existent type declaration throws: MalformedParameterizedTypeException - if any of the generic superinterfaces refer to a parameterized type that cannotbe instantiated for any reason an array of interfaces implemented by this class since: 1.5
Returns the
Type representing the direct superclass of
the entity (class, interface, primitive type or void) represented by
this
Class .
If the superclass is a parameterized type, the
Type object returned must accurately reflect the actual type
parameters used in the source code. The parameterized type
representing the superclass is created if it had not been
created before. See the declaration of
java.lang.reflect.ParameterizedType ParameterizedType for the
semantics of the creation process for parameterized types. If
this
Class represents either the
Object class, an interface, a primitive type, or void, then null is
returned. If this object represents an array class then the
Class object representing the
Object class is
returned.
throws: GenericSignatureFormatError - if the genericclass signature does not conform to the format specified in theJava Virtual Machine Specification, 3rd edition throws: TypeNotPresentException - if the generic superclassrefers to a non-existent type declaration throws: MalformedParameterizedTypeException - if the generic superclass refers to a parameterized type that cannot beinstantiated for any reason the superclass of the class represented by this object since: 1.5
Returns a
Method object that reflects the specified public
member method of the class or interface represented by this
Class object. The
name parameter is a
String specifying the simple name of the desired method. The
parameterTypes parameter is an array of
Class objects that identify the method's formal parameter types, in declared
order. If
parameterTypes is
null , it is
treated as if it were an empty array.
If the
name is "
;"or "
" a
NoSuchMethodException is raised. Otherwise, the method to
be reflected is determined by the algorithm that follows. Let C be the
class represented by this object:
C is searched for any matching methods. If no matching
method is found, the algorithm of step 1 is invoked recursively on
the superclass of C.
If no method was found in step 1 above, the superinterfaces of C
are searched for a matching method. If any such method is found, it
is reflected.
To find a matching method in a class C: If C declares exactly one
public method with the specified name and exactly the same formal
parameter types, that is the method reflected. If more than one such
method is found in C, and one of these methods has a return type that is
more specific than any of the others, that method is reflected;
otherwise one of the methods is chosen arbitrarily.
Note that there may be more than one matching method in a
class because while the Java language forbids a class to
declare multiple methods with the same signature but different
return types, the Java virtual machine does not. This
increased flexibility in the virtual machine can be used to
implement various language features. For example, covariant
returns can be implemented with
; the bridge
method and the method being overridden would have the same
signature but different return types.
See The Java Language Specification, sections 8.2 and 8.4.
Parameters: name - the name of the method Parameters: parameterTypes - the list of parameters the Method object that matches the specified name and parameterTypes exception: NoSuchMethodException - if a matching method is not foundor if the name is "<init>"or "<clinit>". exception: NullPointerException - if name is null exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns an array containing
Method objects reflecting all
the public member methods of the class or interface represented
by this
Class object, including those declared by the class
or interface and those inherited from superclasses and
superinterfaces. Array classes return all the (public) member methods
inherited from the
Object class. The elements in the array
returned are not sorted and are not in any particular order. This
method returns an array of length 0 if this
Class object
represents a class or interface that has no public member methods, or if
this
Class object represents a primitive type or void.
The class initialization method
is not
included in the returned array. If the class declares multiple public
member methods with the same parameter types, they are all included in
the returned array.
See The Java Language Specification, sections 8.2 and 8.4.
the array of Method objects representing thepublic methods of this class exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.PUBLIC) deniesaccess to the methods within this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Returns the Java language modifiers for this class or interface, encoded
in an integer. The modifiers consist of the Java Virtual Machine's
constants for
public ,
protected ,
private ,
final ,
static ,
abstract and
interface ; they should be decoded
using the methods of class
Modifier .
If the underlying class is an array class, then its
public ,
private and
protected modifiers are the same as those of its component type. If this
Class represents a primitive type or void, its
public modifier is always
true , and its
protected and
private modifiers are always
false . If this object represents an array class, a
primitive type or void, then its
final modifier is always
true and its interface modifier is always
false . The values of its other modifiers are not determined
by this specification.
The modifier encodings are defined in The Java Virtual Machine
Specification, table 4.1.
the int representing the modifiers for this class See Also:java.lang.reflect.Modifier since: JDK1.1
Returns the name of the entity (class, interface, array class,
primitive type, or void) represented by this
Class object,
as a
String .
If this class object represents a reference type that is not an
array type then the binary name of the class is returned, as specified
by the Java Language Specification, Second Edition.
If this class object represents a primitive type or void, then the
name returned is a
String equal to the Java language
keyword corresponding to the primitive type or void.
If this class object represents a class of arrays, then the internal
form of the name consists of the name of the element type preceded by
one or more '
[ ' characters representing the depth of the array
nesting. The encoding of element type names is as follows:
Element Type
Encoding
boolean
Z
byte
B
char
C
class or interface
Lclassname;
double
D
float
F
int
I
long
J
short
S
The class or interface name classname is the binary name of
the class specified above.
Examples:
String.class.getName()
returns "java.lang.String"
byte.class.getName()
returns "byte"
(new Object[3]).getClass().getName()
returns "[Ljava.lang.Object;"
(new int[3][4][5][6][7][8][9]).getClass().getName()
returns "[[[[[[[I"
the name of the class or interfacerepresented by this object.
Gets the package for this class. The class loader of this class is used
to find the package. If the class was loaded by the bootstrap class
loader the set of packages loaded from CLASSPATH is searched to find the
package of the class. Null is returned if no package object was created
by the class loader of this class.
Packages have attributes for versions and specifications only if the
information was defined in the manifests that accompany the classes, and
if the class loader created the package instance with the attributes
from the manifest.
the package of the class, or null if no packageinformation is available from the archive or codebase.
Returns the
ProtectionDomain of this class. If there is a
security manager installed, this method first calls the security
manager's
checkPermission method with a
RuntimePermission("getProtectionDomain") permission to
ensure it's ok to get the
ProtectionDomain .
the ProtectionDomain of this class throws: SecurityException - if a security manager exists and its checkPermission method doesn't allow getting the ProtectionDomain. See Also:java.security.ProtectionDomain See Also:SecurityManager.checkPermission See Also:java.lang.RuntimePermission since: 1.2
Finds a resource with a given name. The rules for searching resources
associated with a given class are implemented by the defining
of the class. This method
delegates to this object's class loader. If this object was loaded by
the bootstrap class loader, the method delegates to
ClassLoader.getSystemResource .
Before delegation, an absolute resource name is constructed from the
given resource name using this algorithm:
If the
name begins with a
'/' ('\u002f'), then the absolute name of the resource is the
portion of the
name following the
'/' .
Otherwise, the absolute name is of the following form:
modified_package_name/name
Where the
modified_package_name is the package name of this
object with
'/' substituted for
'.' ('\u002e').
Parameters: name - name of the desired resource A java.net.URL object or null if noresource with this name is found since: JDK1.1
Finds a resource with a given name. The rules for searching resources
associated with a given class are implemented by the defining
of the class. This method
delegates to this object's class loader. If this object was loaded by
the bootstrap class loader, the method delegates to
ClassLoader.getSystemResourceAsStream .
Before delegation, an absolute resource name is constructed from the
given resource name using this algorithm:
If the
name begins with a
'/' ('\u002f'), then the absolute name of the resource is the
portion of the
name following the
'/' .
Otherwise, the absolute name is of the following form:
modified_package_name/name
Where the
modified_package_name is the package name of this
object with
'/' substituted for
'.' ('\u002e').
Parameters: name - name of the desired resource A java.io.InputStream object or null ifno resource with this name is found throws: NullPointerException - If name is null since: JDK1.1
Gets the signers of this class.
the signers of this class, or null if there are no signers. Inparticular, this method returns null if this object representsa primitive type or void. since: JDK1.1
Returns the simple name of the underlying class as given in the
source code. Returns an empty string if the underlying class is
anonymous.
The simple name of an array is the simple name of the
component type with "[]" appended. In particular the simple
name of an array whose component type is anonymous is "[]".
the simple name of the underlying class since: 1.5
getSuperclass
native publicClass<? super T> getSuperclass()(Code)
Returns the
Class representing the superclass of the entity
(class, interface, primitive type or void) represented by this
Class . If this
Class represents either the
Object class, an interface, a primitive type, or void, then
null is returned. If this object represents an array class then the
Class object representing the
Object class is
returned.
the superclass of the class represented by this object.
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.
an array of TypeVariable objects that representthe type variables declared by this generic declaration throws: GenericSignatureFormatError - if the genericsignature of this generic declaration does not conform tothe format specified in the Java Virtual Machine Specification,3rd edition since: 1.5
Returns true if this
Class object represents an annotation
type. Note that if this method returns true,
Class.isInterface() would also return true, as all annotation types are also interfaces.
true if this class object represents an annotationtype; false otherwise since: 1.5
isAnnotationPresent
public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)(Code)
Determines if this
Class object represents an array class.
true if this object represents an array class; false otherwise. since: JDK1.1
isAssignableFrom
native public boolean isAssignableFrom(Class cls)(Code)
Determines if the class or interface represented by this
Class object is either the same as, or is a superclass or
superinterface of, the class or interface represented by the specified
Class parameter. It returns
true if so;
otherwise it returns
false . If this
Class object represents a primitive type, this method returns
true if the specified
Class parameter is
exactly this
Class object; otherwise it returns
false .
Specifically, this method tests whether the type represented by the
specified
Class parameter can be converted to the type
represented by this
Class object via an identity conversion
or via a widening reference conversion. See The Java Language
Specification, sections 5.1.1 and 5.1.4 , for details.
Parameters: cls - the Class object to be checked the boolean value indicating whether objects of thetype cls can be assigned to objects of this class exception: NullPointerException - if the specified Class parameter isnull. since: JDK1.1
Returns true if and only if this class was declared as an enum in the
source code.
true if and only if this class was declared as an enum in thesource code since: 1.5
isInstance
native public boolean isInstance(Object obj)(Code)
Determines if the specified
Object is assignment-compatible
with the object represented by this
Class . This method is
the dynamic equivalent of the Java language
instanceof operator. The method returns
true if the specified
Object argument is non-null and can be cast to the
reference type represented by this
Class object without
raising a
ClassCastException. It returns
false otherwise.
Specifically, if this
Class object represents a
declared class, this method returns
true if the specified
Object argument is an instance of the represented class (or
of any of its subclasses); it returns
false otherwise. If
this
Class object represents an array class, this method
returns
true if the specified
Object argument
can be converted to an object of the array class by an identity
conversion or by a widening reference conversion; it returns
false otherwise. If this
Class object
represents an interface, this method returns
true if the
class or any superclass of the specified
Object argument
implements this interface; it returns
false otherwise. If
this
Class object represents a primitive type, this method
returns
false .
Parameters: obj - the object to check true if obj is an instance of this class since: JDK1.1
Determines if the specified
Class object represents a
primitive type.
There are nine predefined
Class objects to represent
the eight primitive types and void. These are created by the Java
Virtual Machine, and have the same names as the primitive types that
they represent, namely
boolean ,
byte ,
char ,
short ,
int ,
long ,
float , and
double .
Returns
true if this class is a synthetic class;
returns
false otherwise.
true if and only if this class is a synthetic class asdefined by the Java Language Specification. since: 1.5
Creates a new instance of the class represented by this
Class object. The class is instantiated as if by a
new expression with an empty argument list. The class is initialized if it
has not already been initialized.
Note that this method propagates any exception thrown by the
nullary constructor, including a checked exception. Use of
this method effectively bypasses the compile-time exception
checking that would otherwise be performed by the compiler.
The
java.lang.reflect.Constructor.newInstance(java.lang.Object)Constructor.newInstance method avoids this problem by wrapping
any exception thrown by the constructor in a (checked)
java.lang.reflect.InvocationTargetException .
a newly allocated instance of the class represented by thisobject. exception: IllegalAccessException - if the class or its nullary constructor is not accessible. exception: InstantiationException - if this Class represents an abstract class,an interface, an array class, a primitive type, or void;or if the class has no nullary constructor;or if the instantiation fails for some other reason. exception: ExceptionInInitializerError - if the initializationprovoked by this method fails. exception: SecurityException - If a security manager, s, is present and any of thefollowing conditions is met:
invocation of SecurityManager.checkMemberAccesss.checkMemberAccess(this, Member.PUBLIC) deniescreation of new instances of this class
the caller's class loader is not the same as or anancestor of the class loader for the current class andinvocation of SecurityManager.checkPackageAccesss.checkPackageAccess() denies access to the packageof this class
Converts the object to a string. The string representation is the
string "class" or "interface", followed by a space, and then by the
fully qualified name of the class in the format returned by
getName . If this
Class object represents a
primitive type, this method returns the name of the primitive type. If
this
Class object represents void this method returns
"void".
a string representation of this class object.
