Instances of the class Class represent classes and
interfaces in a running Java application.
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. Finally, the either primitive Java types
(boolean, byte, char, short, int, long, float, and double) and
the keyword void are also represented as Class objects.
There is no public constructor for the class Class.
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());
}
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 and those inherited from
superclasses and superinterfaces.
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.
Converts the object to a string. The string representation is the
string "class" or "interface" followed
by a space and then the fully qualified name of the class.
If this Class object represents a primitive type,
returns the name of the primitive type.
Returns the Class object associated with the class
with the given string name.
Given the fully-qualified name for a class or interface, this
method attempts to locate, load and link the class. If it
succeeds, returns the Class object representing the class. If
it fails, the method throws a ClassNotFoundException.
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")
Parameters:
className - the fully qualified name of the desired class.
Returns:
the Class descriptor for the class with the
specified name.
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, returns true if the specified Object argument is an
instance of the represented class (or of any of its
subclasses); false otherwise. If this Class object represents
an array class, returns true if the specified Object argument
can be converted to an object of the array type by an identity
conversion or by a widening reference conversion; false
otherwise. If this Class object represents an interface,
returns true if the class or any superclass of the
specified Object argument implements this interface; false
otherwise. If this Class object represents a primitive type,
returns false.
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, false otherwise. If this Class object represents a
primitive type, returns true if the specified Class parameter
is exactly this Class object, false otherwise.
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.
Determines if the specified Class object represents a primitive Java
type.
There are nine predefined Class objects to represent the eight
primitive Java 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, and void.
These objects may only be accessed via the following public
static final variables, and are the only Class objects for
which this method returns true.
Determines the interfaces implemented by the class or interface
represented by this object.
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.
If this object represents an interface, the array contains
objects representing all interfaces 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 the class or interface implements no interfaces, the method
returns an array of length 0.
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, and interface; they should be decoded using the
methods of class Modifier.
The modifier encodings are defined in The Java Virtual
Machine Specification, table 4.1.
Not implemented in this version of the
JavaTM Development Kit.
If the class or interface represented by this Class object is
a member of another class, returns the Class object
representing the class of which it is a member (its
declaring class). Returns null if this class or
interface is not a member of any other class.
Not implemented in this version of the
JavaTM Development Kit.
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. Returns an
array of length 0 if the class has no public member classes or
interfaces, or if this Class object represents a primitive
type.
Returns an array containing Field objects reflecting all the
accessible public fields of the class or interface represented
by this Class object. Returns an array of length 0 if the
class or interface has no accessible public fields, or if it
represents an array type or a primitive type.
Specifically, if this Class object represents a class,
returns the public fields of this class and of all its
superclasses. If this Class object represents an interface,
returns the fields of this interface and of all its
superinterfaces. If this Class object represents an array type
or a primitive type, returns an array of length 0.
The implicit length field for array types 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.
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 and those inherited from
superclasses and superinterfaces. Returns an array of length 0
if the class or interface has no public member methods.
See The Java Language Specification, sections 8.2
and 8.4.
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.
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 located by searching all the
member fields of the class or interface represented by this
Class object for a public field with the specified name.
See The Java Language Specification, sections 8.2 and 8.3.
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 the desired method, and the parameterTypes
parameter is an array of Class objects that identify the
method's formal parameter types, in declared order.
The method to reflect is located by searching all the member
methods of the class or interface represented by this Class
object for a public method with the specified name and exactly
the same formal parameter types.
See The Java Language Specification, sections 8.2
and 8.4.
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.
The constructor to reflect is located by searching all the
constructors of the class represented by this Class object for
a public constructor with the exactly the same formal parameter
types.
Not implemented in this version of the
JavaTM Development Kit.
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.
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.
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. Returns an array of length 0 if the class or interface
declares no fields, or if this Class object represents a
primitive type.
See The Java Language Specification, sections 8.2 and
8.3.
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. Returns an array of length 0 if the class or interface
declares no methods, or if this Class object represents a
primitive type.
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. Returns an array of length 0 if this
Class object represents an interface or a primitive type.
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.
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.
Returns a Constructor object that reflects the specified declared
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.
Finds a resource with a given name. Will return null if no
resource with this name is found. The rules for searching a
resources associated with a given class are implemented by the
ClassLoader of the class.
The Class methods delegate to ClassLoader methods, after applying
a naming convention: if the resource name starts with "/", it is used
as is. Otherwise, the name of the package is prepended, after
converting "." to "/".
Parameters:
name - the string representing the resource to be found
Returns:
the InputStream object having the
specified name, or null if no
resource with the specified name is found.
Finds a resource with the specified name. The rules for searching
for resources associated with a given class are implemented by
the class loader of the class.
The Class methods delegate to ClassLoader methods, after applying
a naming convention: if the resource name starts with "/", it is used
as is. Otherwise, the name of the package is prepended, after
converting "." to "/".
Parameters:
name - the string representing the resource to be found.
Returns:
the URL object having the specified name,
or null if no resource with the specified
name is found.
Submit a bug or feature - Version 1.1.8 of Java Platform API Specification
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.
Copyright 1995-1999 Sun Microsystems, Inc. 901 San Antonio Road,
Palo Alto, California, 94303, U.S.A. All Rights Reserved.