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FlexDoc/Javadoc 2.0 Demo Java Doc |
Class Class<T>
java.lang.Class<T>
Type Parameters:
T - the type of the class modeled by this
Class
object. For example, the type of
String.class is
Class<String>. Use
Class<?> if the class being modeled is
unknown.
All Implemented Interfaces:
public final class Class<T>
Instances of the class
Class represent classes and
interfaces in a running Java application. An enum class and a record
class are kinds of class; an annotation interface 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 a Class
object is constructed automatically by the Java Virtual Machine when
a class is derived from the bytes of a class file through
the invocation of one of the following methods:
The methods of class Class expose many characteristics of a
class or interface. Most characteristics are derived from the class
file that the class loader passed to the Java Virtual Machine or
from the class file passed to Lookup::defineClass
or Lookup::defineHiddenClass.
A few characteristics are determined by the class loading environment
at run time, such as the module returned by getModule().
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
class or interface (or for
void) using a
class literal.
For example:
System.out.println("The name of class Foo is: "+Foo.class.getName());
Some methods of class Class expose whether the declaration of
a class or interface in Java source code was enclosed within
another declaration. Other methods describe how a class or interface
is situated in a nest. A nest is a set of
classes and interfaces, in the same run-time package, that
allow mutual access to their private members.
The classes and interfaces are known as nestmates.
One nestmate acts as the
nest host, and enumerates the other nestmates which
belong to the nest; each of them in turn records it as the nest host.
The classes and interfaces which belong to a nest, including its host, are
determined when
class files are generated, for example, a Java compiler
will typically record a top-level class as the host of a nest where the
other members are the classes and interfaces whose declarations are
enclosed within the top-level class declaration.
A class or interface created by the invocation of
Lookup::defineHiddenClass is a hidden
class or interface.
All kinds of class, including enum classes and record classes, may be
hidden classes; all kinds of interface, including annotation interfaces,
may be hidden interfaces.
The name of a hidden class or interface is
not a binary name,
which means the following:
A hidden class or interface is never an array class, but may be
the element type of an array. In all other respects, the fact that
a class or interface is hidden has no bearing on the characteristics
exposed by the methods of class
Class.
Since:
1.0
See Also:
Nested classes/interfaces inherited from interface java.lang.invoke. TypeDescriptor |
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Method Summary |
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Returns a Class for an array type whose component type
is described by this Class.
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Casts this Class object to represent a subclass of the class
represented by the specified class object.
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Casts an object to the class or interface represented
by this Class object.
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Returns the component type of this Class, if it describes
an array type, or null otherwise.
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Returns a nominal descriptor for this instance, if one can be
constructed, or an empty Optional if one cannot be.
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Returns the descriptor string of the entity (class, interface, array class,
primitive type, or void) represented by this Class object.
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boolean |
Returns the assertion status that would be assigned to this
class if it were to be initialized at the time this method is invoked.
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Returns the Class with the given
binary name in the given module.
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Returns the Class object associated with the class or
interface with the given string name.
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Returns the Class object associated with the class or
interface with the given string name, using the given class loader.
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Returns an array of AnnotatedType objects that represent the use
of types to specify superinterfaces of the entity represented by this
Class object.
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Returns an AnnotatedType object that represents the use of a
type to specify the superclass of the entity represented by this
Class object.
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Returns this element's annotation for the specified type if
such an annotation is present, else null.
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Returns annotations that are present on this element.
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Returns annotations that are associated with this element.
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Returns the canonical name of the underlying class as
defined by The Java Language Specification.
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Returns an array containing Class objects representing all
the public classes and interfaces that are members of the class
represented by this Class object.
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Returns the class loader for the class.
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Returns the Class representing the component type of an
array.
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Returns a Constructor object that reflects the specified
public constructor of the class represented by this Class
object.
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Returns an array containing Constructor objects reflecting
all the public constructors of the class represented by this
Class object.
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Returns this element's annotation for the specified type if
such an annotation is directly present, else null.
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Returns annotations that are directly present on this element.
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Returns this element's annotation(s) for the specified type if
such annotations are either directly present or
indirectly present.
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Returns an array of Class objects reflecting all the
classes and interfaces declared as members of the class represented by
this Class object.
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Returns a Constructor object that reflects the specified
constructor of the class or interface represented by this
Class object.
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Returns an array of Constructor objects reflecting all the
constructors declared by the class represented by this
Class object.
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Returns a Field object that reflects the specified declared
field of the class or interface represented by this Class
object.
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Returns an array of Field objects reflecting all the fields
declared by the class or interface represented by this
Class object.
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Returns a Method object that reflects the specified
declared method of the class or interface represented by this
Class object.
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Returns an array containing Method objects reflecting all the
declared methods of the class or interface represented by this
Class object, including public, protected, default (package)
access, and private methods, but excluding inherited methods.
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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.
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Returns the immediately enclosing class of the underlying
class.
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If this Class object represents a local or anonymous
class within a constructor, returns a Constructor object representing
the immediately enclosing constructor of the underlying
class.
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If this Class object represents a local or anonymous
class within a method, returns a Method object representing the
immediately enclosing method of the underlying class.
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Returns the elements of this enum class or null if this
Class object does not represent an enum class.
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Returns a Field object that reflects the specified public member
field of the class or interface represented by this Class
object.
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Returns an array containing Field objects reflecting all
the accessible public fields of the class or interface represented by
this Class object.
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Returns the Types representing the interfaces
directly implemented by the class or interface represented by
this Class object.
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Returns the Type representing the direct superclass of
the entity (class, interface, primitive type or void) represented by
this Class object.
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Returns the interfaces directly implemented by the class or interface
represented by this Class object.
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Returns a Method object that reflects the specified public
member method of the class or interface represented by this
Class object.
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Returns an array containing Method objects reflecting all the
public 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.
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int |
Returns the Java language modifiers for this class or interface, encoded
in an integer.
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Returns the module that this class or interface is a member of.
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Returns the name of the entity (class, interface, array class,
primitive type, or void) represented by this Class object.
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Returns the nest host of the nest to which the class
or interface represented by this Class object belongs.
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Returns an array containing Class objects representing all the
classes and interfaces that are members of the nest to which the class
or interface represented by this Class object belongs.
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Gets the package of this class.
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Returns the fully qualified package name.
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Returns an array containing Class objects representing the
direct subinterfaces or subclasses permitted to extend or
implement this class or interface if it is sealed.
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Returns the ProtectionDomain of this class.
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Returns an array of RecordComponent objects representing all the
record components of this record class, or null if this class is
not a record class.
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Finds a resource with a given name.
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Finds a resource with a given name.
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Gets the signers of this class.
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Returns the simple name of the underlying class as given in the
source code.
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Returns the Class representing the direct superclass of the
entity (class, interface, primitive type or void) represented by
this Class.
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Return an informative string for the name of this class or interface.
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Returns an array of TypeVariable objects that represent the
type variables declared by the generic declaration represented by this
GenericDeclaration object, in declaration order.
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boolean |
Returns true if this Class object represents an annotation
interface.
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boolean |
Returns true if an annotation for the specified type
is present on this element, else false.
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boolean |
Returns true if and only if the underlying class
is an anonymous class.
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boolean |
Determines if this Class object represents an array class.
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boolean |
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.
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boolean |
Returns true if and only if this class was declared as an enum in the
source code.
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boolean |
Returns true if and only if the underlying class is a hidden class.
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boolean |
Determines if the specified Object is assignment-compatible
with the object represented by this Class.
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boolean |
Determines if this Class object represents an
interface type.
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boolean |
Returns true if and only if the underlying class
is a local class.
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boolean |
Returns true if and only if the underlying class
is a member class.
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boolean |
Determines if the given Class is a nestmate of the
class or interface represented by this Class object.
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boolean |
Determines if the specified Class object represents a
primitive type.
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boolean |
Returns true if and only if this class is a record class.
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boolean |
Returns true if and only if this Class object represents
a sealed class or interface.
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boolean |
Returns true if and only if this class has the synthetic modifier
bit set
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Deprecated. This method propagates any exception thrown by the
nullary constructor, including a checked exception.
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Returns a string describing this Class, including
information about modifiers and type parameters.
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Converts the object to a string.
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Methods inherited from class java.lang. Object |
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Converts the object to a string. The string representation is the
string "class" or "interface", followed by a space, and then by the
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". If this
Class object represents an array type,
this method returns "class " followed by
getName.
Overrides:
Returns:
a string representation of this Class object.
Returns a string describing this
Class, including
information about modifiers and type parameters.
The string is formatted as a list of type modifiers, if any,
followed by the kind of type (empty string for primitive types
and
class,
enum,
interface,
@interface, or
record as appropriate), followed
by the type's name, followed by an angle-bracketed
comma-separated list of the type's type parameters, if any,
including informative bounds on the type parameters, if any.
A space is used to separate modifiers from one another and to
separate any modifiers from the kind of type. The modifiers
occur in canonical order. If there are no type parameters, the
type parameter list is elided.
For an array type, the string starts with the type name,
followed by an angle-bracketed comma-separated list of the
type's type parameters, if any, followed by a sequence of
[] characters, one set of brackets per dimension of
the array.
Note that since information about the runtime representation
of a type is being generated, modifiers not present on the
originating source code or illegal on the originating source
code may be present.
Returns:
a string describing this Class, including
information about modifiers and type parameters
Since:
1.8
public static Class<?> forName |
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throws |
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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.
Returns:
the Class object for the class with the
specified name.
Throws:
public static Class<?> forName |
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throws |
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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 and load 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:
Class.forName("Foo")
is equivalent to:
Class.forName("Foo", true, this.getClass().getClassLoader())
Note that this method throws errors related to loading, linking
or initializing as specified in Sections {@jls 12.2}, {@jls 12.3}, and {@jls 12.4} of
The Java Language
Specification.
Note that this method does not check whether the requested class
is accessible to its caller.
Parameters:
name - fully qualified name of the desired class
initialize - if true the class will be initialized
(which implies linking). See Section {@jls 12.4} of The Java Language
Specification.
loader - class loader from which the class must be loaded
Returns:
class object representing the desired class
Throws:
Since:
1.2
See Also:
public static Class<?> forName |
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Returns the
Class with the given
binary name in the given module.
This method attempts to locate and load the class or interface.
It does not link the class, and does not run the class initializer.
If the class is not found, this method returns null.
If the class loader of the given module defines other modules and
the given name is a class defined in a different module, this method
returns null after the class is loaded.
This method does not check whether the requested class is
accessible to its caller.
Parameters:
Returns:
Class object of the given name defined in the given module;
null if not found.
Throws:
NullPointerException - if the given module or name is
null
SecurityException -
- if the caller is not the specified module and
RuntimePermission("getClassLoader") permission is denied; or
- access to the module content is denied. For example,
permission check will be performed when a class loader calls
ModuleReader.open(String) to read the bytes of a class file
in a module.
Since:
9
Deprecated. 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 Constructor.newInstance method avoids this problem by wrapping
any exception thrown by the constructor in a (checked) InvocationTargetException.
The call
clazz.newInstance()
can be replaced by
clazz.getDeclaredConstructor().newInstance()
The latter sequence of calls is inferred to be able to throw
the additional exception types InvocationTargetException and NoSuchMethodException. Both of these exception types are
subclasses of ReflectiveOperationException.
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.
Returns:
a newly allocated instance of the class represented by this
object.
Throws:
IllegalAccessException - if the class or its nullary
constructor is not accessible.
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.
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
public boolean isInstance |
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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
Returns:
true if obj is an instance of this class
Since:
1.1
public boolean isAssignableFrom |
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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 {@jls 5.1.1} and {@jls 5.1.4},
for details.
Parameters:
cls - the Class object to be checked
Returns:
the boolean value indicating whether objects of the
type cls can be assigned to objects of this class
Throws:
Since:
1.1
public boolean isInterface |
() |
Determines if this
Class object represents an
interface type.
Returns:
true if this Class object represents an interface;
false otherwise.
public boolean isArray |
() |
Determines if this
Class object represents an array class.
Specified by:
Returns:
true if this Class object represents an array class;
false otherwise.
Since:
1.1
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. 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.
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.
Specified by:
Returns:
true if and only if this class represents a primitive type
Since:
1.1
See Also:
public boolean isAnnotation |
() |
Returns true if this
Class object represents an annotation
interface. Note that if this method returns true,
isInterface()
would also return true, as all annotation interfaces are also interfaces.
Returns:
true if this Class object represents an annotation
interface; false otherwise
Since:
1.5
public boolean isSynthetic |
() |
Returns
true if and only if this class has the synthetic modifier
bit set
Returns:
true if and only if this class has the synthetic modifier
bit set
Since:
1.5
See Also:
Returns the name of the entity (class, interface, array class,
primitive type, or void) represented by this
Class object.
If this Class object represents a class or interface,
not an array class, then:
- If the class or interface is not hidden,
then the binary name
of the class or interface is returned.
- If the class or interface is hidden, then the result is a string
of the form: N + '/' + <suffix>
where N is the binary name
indicated by the class file passed to
Lookup::defineHiddenClass, and <suffix> is an unqualified name.
If this Class object represents an array class, then
the result is a string consisting of one or more '[' characters
representing the depth of the array nesting, followed by the element
type as encoded using the following table:
Element types and encodings
Element Type | Encoding
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boolean | Z
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byte | B
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char | C
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class or interface with binary name N
| LN;
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double | D
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float | F
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int | I
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long | J
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short | S
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If this Class object represents a primitive type or void,
then the result is a string with the same spelling as the Java language
keyword which corresponds to the primitive type or void.
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"
Returns:
the name of the class, interface, or other entity
represented by this Class object.
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 this Class object
represents a primitive type or void, null is returned.
Returns:
the class loader that loaded the class or interface
represented by this Class object.
Throws:
SecurityException - if a security manager is present, and the caller's class loader
is not
null and is not the same as or an ancestor of the
class loader for the class whose class loader is requested,
and the caller does not have the
RuntimePermission("getClassLoader") See Also:
Returns the module that this class or interface is a member of.
If this class represents an array type then this method returns the
Module for the element type. If this class represents a
primitive type or void, then the
Module object for the
java.base module is returned.
If this class is in an unnamed module then the
unnamed Module of the class
loader for this class is returned.
Returns:
the module that this class or interface is a member of
Since:
9
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:
Returns:
an array of TypeVariable objects that represent
the type variables declared by this generic declaration
Throws:
GenericSignatureFormatError - if the generic
signature of this generic declaration does not conform to
the format specified in section {@jvms 4.7.9} of
The Java Virtual Machine Specification Since:
1.5
public Class<? super T> getSuperclass |
() |
Returns the
Class representing the direct 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
Class object represents an array class
then the
Class object representing the
Object class is
returned.
Returns:
the direct superclass of the class represented by this Class object
public Type getGenericSuperclass |
() |
Returns the
Type representing the direct superclass of
the entity (class, interface, primitive type or void) represented by
this
Class object.
If the superclass is a parameterized type, the Type
object returned must accurately reflect the actual type
arguments used in the source code. The parameterized type
representing the superclass is created if it had not been
created before. See the declaration of ParameterizedType for the
semantics of the creation process for parameterized types. If
this Class object represents either the Object
class, an interface, a primitive type, or void, then null is
returned. If this Class object represents an array class
then the Class object representing the Object class is
returned.
Returns:
the direct superclass of the class represented by this Class object
Throws:
GenericSignatureFormatError - if the generic
class signature does not conform to the format specified in
section {@jvms 4.7.9} of
The Java Virtual
Machine Specification
Since:
1.5
Gets the package of this class.
If this class represents an array type, a primitive type or void,
this method returns null.
Returns:
the package of this class.
Returns the fully qualified package name.
If this class is a top level class, then this method returns the fully
qualified name of the package that the class is a member of, or the
empty string if the class is in an unnamed package.
If this class is a member class, then this method is equivalent to
invoking getPackageName() on the enclosing class.
If this class is a local class or an anonymous class, then this method is equivalent to
invoking getPackageName() on the declaring class of the enclosing method or
enclosing constructor.
If this class represents an array type then this method returns the
package name of the element type. If this class represents a primitive
type or void then the package name "java.lang" is returned.
Returns:
the fully qualified package name
Since:
9
public Class<?>[] getInterfaces |
() |
Returns the interfaces directly implemented by the class or interface
represented by this
Class object.
If this Class object represents a class, the return value is an array
containing objects representing all interfaces directly 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 Class object. For example,
given the declaration:
class Shimmer implements FloorWax, DessertTopping { ... }
suppose the value of
s is an instance of
Shimmer; the value of the expression:
s.getClass().getInterfaces()[0]
is the
Class object that represents interface
FloorWax; and the value of:
s.getClass().getInterfaces()[1]
is the
Class object that represents interface
DessertTopping.
If this Class 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 Class object.
If this Class object represents a class or interface that implements no
interfaces, the method returns an array of length 0.
If this Class object represents a primitive type or void, the method
returns an array of length 0.
If this Class object represents an array type, the
interfaces Cloneable and java.io.Serializable are
returned in that order.
Returns:
an array of interfaces directly implemented by this class
public Type[] getGenericInterfaces |
() |
Returns the
Types representing the interfaces
directly implemented by the class or interface represented by
this
Class object.
If a superinterface is a parameterized type, the
Type object returned for it must accurately reflect
the actual type arguments used in the source code. The
parameterized type representing each superinterface is created
if it had not been created before. See the declaration of
ParameterizedType
for the semantics of the creation process for parameterized
types.
If this Class object represents a class, the return value is an array
containing objects representing all interfaces directly 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 Class object.
If this Class 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 Class object.
If this Class object represents a class or interface that implements no
interfaces, the method returns an array of length 0.
If this Class object represents a primitive type or void, the method
returns an array of length 0.
If this Class object represents an array type, the
interfaces Cloneable and java.io.Serializable are
returned in that order.
Returns:
an array of interfaces directly implemented by this class
Throws:
GenericSignatureFormatError - if the generic class signature does not conform to the
format specified in section {@jvms 4.7.9} of
The
Java Virtual Machine Specification
Since:
1.5
public Class<?> getComponentType |
() |
Returns the
Class representing the component type of an
array. If this class does not represent an array class this method
returns null.
Returns:
the Class representing the component type of this
class if this class is an array
Since:
1.1
See Also:
public int getModifiers |
() |
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 object represents a primitive type or void, its
public modifier is always true, and its
protected and private modifiers are always
false. If this Class 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 section {@jvms 4.1}
of The Java Virtual Machine Specification.
Returns:
the int representing the modifiers for this class
Since:
1.1
See Also:
Gets the signers of this class.
Returns:
the signers of this class, or null if there are no signers. In
particular, this method returns null if this Class object represents
a primitive type or void.
Since:
1.1
public Method getEnclosingMethod |
() |
throws |
|
If this
Class object represents a local or anonymous
class within a method, returns a
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 class or
interface declaration, instance initializer or static initializer.
Returns:
the immediately enclosing method of the underlying class, if
that class is a local or anonymous class; otherwise null.
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of the enclosing class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the methods within the enclosing class
- the caller's class loader is not the same as or an
ancestor of the class loader for the enclosing class and
invocation of s.checkPackageAccess() denies access to the package
of the enclosing class
Since:
1.5
If this
Class object represents a local or anonymous
class within a constructor, returns a
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 class or
interface declaration, instance initializer or static initializer.
Returns:
the immediately enclosing constructor of the underlying class, if
that class is a local or anonymous class; otherwise null.
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of the enclosing class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the constructors within the enclosing class
- the caller's class loader is not the same as or an
ancestor of the class loader for the enclosing class and
invocation of s.checkPackageAccess() denies access to the package
of the enclosing class
Since:
1.5
public Class<?> getDeclaringClass |
() |
throws |
|
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.
Returns:
the declaring class for this class
Throws:
SecurityException - If a security manager,
s, is present and the caller's
class loader is not the same as or an ancestor of the class
loader for the declaring class and invocation of
s.checkPackageAccess()
denies access to the package of the declaring class
Since:
1.1
public Class<?> getEnclosingClass |
() |
throws |
|
Returns the immediately enclosing class of the underlying
class. If the underlying class is a top level class this
method returns
null.
Returns:
the immediately enclosing class of the underlying class
Throws:
SecurityException - If a security manager,
s, is present and the caller's
class loader is not the same as or an ancestor of the class
loader for the enclosing class and invocation of
s.checkPackageAccess()
denies access to the package of the enclosing class
Since:
1.5
Returns the simple name of the underlying class as given in the
source code. An empty string is returned if the underlying class is
anonymous.
A
synthetic class, one not present
in source code, can have a non-empty name including special
characters, such as "
$".
The simple name of an array class is the simple name of the
component type with "[]" appended. In particular the simple
name of an array class whose component type is anonymous is "[]".
Returns:
the simple name of the underlying class
Since:
1.5
Return an informative string for the name of this class or interface.
Specified by:
Returns:
an informative string for the name of this class or interface
Since:
1.8
public String getCanonicalName |
() |
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. Classes without canonical names include:
Returns:
the canonical name of the underlying class if it exists, and
null otherwise.
Since:
1.5
public boolean isAnonymousClass |
() |
Returns
true if and only if the underlying class
is an anonymous class.
Returns:
true if and only if this class is an anonymous class.
Since:
1.5
public boolean isLocalClass |
() |
Returns
true if and only if the underlying class
is a local class.
Returns:
true if and only if this class is a local class.
Since:
1.5
public boolean isMemberClass |
() |
Returns
true if and only if the underlying class
is a member class.
Returns:
true if and only if this class is a member class.
Since:
1.5
public Class<?>[] 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. 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.
Returns:
the array of Class objects representing the public
members of this class
Throws:
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
Returns an array containing
Field objects reflecting all
the accessible public fields of the class or interface represented by
this
Class object.
If this Class object represents a class or interface with
no accessible public fields, then this method returns an array of length
0.
If this Class object represents a class, then this method
returns the public fields of the class and of all its superclasses and
superinterfaces.
If this Class object represents an interface, then this
method returns the fields of the interface and of all its
superinterfaces.
If this Class object represents an array type, a primitive
type, or void, then this method returns an array of length 0.
The elements in the returned array are not sorted and are not in any
particular order.
Returns:
the array of Field objects representing the
public fields
Throws:
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
Returns an array containing
Method objects reflecting all the
public 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.
If this Class object represents an array type, then the
returned array has a Method object for each of the public
methods inherited by the array type from Object. It does not
contain a Method object for clone().
If this Class object represents an interface then the
returned array does not contain any implicitly declared methods from
Object. Therefore, if no methods are explicitly declared in
this interface or any of its superinterfaces then the returned array
has length 0. (Note that a Class object which represents a class
always has public methods, inherited from Object.)
The returned array never contains methods with names "<init>"
or "<clinit>".
The elements in the returned array are not sorted and are not in any
particular order.
Generally, the result is computed as with the following 4 step algorithm.
Let C be the class or interface represented by this Class object:
- A union of methods is composed of:
- C's declared public instance and static methods as returned by
getDeclaredMethods() and filtered to include only public
methods.
- If C is a class other than Object, then include the result
of invoking this algorithm recursively on the superclass of C.
- Include the results of invoking this algorithm recursively on all
direct superinterfaces of C, but include only instance methods.
- Union from step 1 is partitioned into subsets of methods with same
signature (name, parameter types) and return type.
- Within each such subset only the most specific methods are selected.
Let method M be a method from a set of methods with same signature
and return type. M is most specific if there is no such method
N != M from the same set, such that N is more specific than M.
N is more specific than M if:
- N is declared by a class and M is declared by an interface; or
- N and M are both declared by classes or both by interfaces and
N's declaring type is the same as or a subtype of M's declaring type
(clearly, if M's and N's declaring types are the same type, then
M and N are the same method).
- The result of this algorithm is the union of all selected methods from
step 3.
Returns:
the array of Method objects representing the
public methods of this class
Throws:
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
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.
Returns:
the array of Constructor objects representing the
public constructors of this class
Throws:
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
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 or interface represented by this Class 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.
If this Class object represents an array type, then this
method does not find the length field of the array type.
Parameters:
name - the field name
Returns:
the Field object of this class specified by
name
Throws:
NoSuchFieldException - if a field with the specified name is
not found.
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
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 this Class object represents an array type, then this
method finds any public method inherited by the array type from
Object except method clone().
If this Class object represents an interface then this
method does not find any implicitly declared method from
Object. Therefore, if no methods are explicitly declared in
this interface or any of its superinterfaces, then this method does not
find any method.
This method does not find any method with name "<init>" or
"<clinit>".
Generally, the method to be reflected is determined by the 4 step
algorithm that follows.
Let C be the class or interface represented by this Class object:
- A union of methods is composed of:
- C's declared public instance and static methods as returned by
getDeclaredMethods() and filtered to include only public
methods that match given name and parameterTypes
- If C is a class other than Object, then include the result
of invoking this algorithm recursively on the superclass of C.
- Include the results of invoking this algorithm recursively on all
direct superinterfaces of C, but include only instance methods.
- This union is partitioned into subsets of methods with same
return type (the selection of methods from step 1 also guarantees that
they have the same method name and parameter types).
- Within each such subset only the most specific methods are selected.
Let method M be a method from a set of methods with same VM
signature (return type, name, parameter types).
M is most specific if there is no such method N != M from the same
set, such that N is more specific than M. N is more specific than M
if:
- N is declared by a class and M is declared by an interface; or
- N and M are both declared by classes or both by interfaces and
N's declaring type is the same as or a subtype of M's declaring type
(clearly, if M's and N's declaring types are the same type, then
M and N are the same method).
- The result of this algorithm is chosen arbitrarily from the methods
with most specific return type among all selected methods from step 3.
Let R be a return type of a method M from the set of all selected methods
from step 3. M is a method with most specific return type if there is
no such method N != M from the same set, having return type S != R,
such that S is a subtype of R as determined by
R.class.isAssignableFrom(Class)(S.class).
Parameters:
name - the name of the method
parameterTypes - the list of parameters
Returns:
the Method object that matches the specified
name and parameterTypes
Throws:
NoSuchMethodException - if a matching method is not found
or if the name is "<init>"or "<clinit>".
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
|
( Class<?>... parameterTypes) |
throws |
|
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
Returns:
the Constructor object of the public constructor that
matches the specified parameterTypes
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager,
s, is present and
the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of
s.checkPackageAccess() denies access to the package
of this class.
Since:
1.1
public Class<?>[] getDeclaredClasses |
() |
throws |
|
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.
Returns:
the array of Class objects representing all the
declared members of this class
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared classes within this class
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
public Field[] getDeclaredFields |
() |
throws |
|
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.
If this Class object represents a class or interface with no
declared fields, then this method returns an array of length 0.
If this Class object represents an array type, a primitive
type, or void, then this method returns an array of length 0.
The elements in the returned array are not sorted and are not in any
particular order.
Returns:
the array of Field objects representing all the
declared fields of this class
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared fields within this class
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
Returns an array of
RecordComponent objects representing all the
record components of this record class, or
null if this class is
not a record class.
The components are returned in the same order that they are declared
in the record header. The array is empty if this record class has no
components. If the class is not a record class, that is isRecord() returns false, then this method returns null.
Conversely, if isRecord() returns true, then this method
returns a non-null value.
Returns:
An array of RecordComponent objects representing all the
record components of this record class, or null if this
class is not a record class
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared methods within this class
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
16
public Method[] getDeclaredMethods |
() |
throws |
|
Returns an array containing
Method objects reflecting all the
declared methods of the class or interface represented by this
Class object, including public, protected, default (package)
access, and private methods, but excluding inherited methods.
The declared methods may include methods
not in the
source of the class or interface, including
bridge methods and other
synthetic methods added by compilers.
If this Class object represents a class or interface that
has multiple declared methods with the same name and parameter types,
but different return types, then the returned array has a Method
object for each such method.
If this Class object represents a class or interface that
has a class initialization method <clinit>, then the returned
array does not have a corresponding Method object.
If this Class object represents a class or interface with no
declared methods, then the returned array has length 0.
If this Class object represents an array type, a primitive
type, or void, then the returned array has length 0.
The elements in the returned array are not sorted and are not in any
particular order.
Returns:
the array of Method objects representing all the
declared methods of this class
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared methods within this class
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
See Also:
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 {@jls 8.2}.
Returns:
the array of Constructor objects representing all the
declared constructors of this class
Throws:
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared constructors within this class
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
public Field getDeclaredField |
|
throws |
|
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.
If this Class object represents an array type, then this
method does not find the length field of the array type.
Parameters:
name - the name of the field
Returns:
the Field object for the specified field in this
class
Throws:
NoSuchFieldException - if a field with the specified name is
not found.
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared field
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
public Method getDeclaredMethod |
|
throws |
|
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.
If this Class object represents an array type, then this
method does not find the clone() method.
Parameters:
name - the name of the method
parameterTypes - the parameter array
Returns:
the Method object for the method of this class
matching the specified name and parameters
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared method
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
|
( Class<?>... parameterTypes) |
throws |
|
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
Returns:
The Constructor object for the constructor with the
specified parameter list
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager,
s, is present and any of the
following conditions is met:
- the caller's class loader is not the same as the
class loader of this class and invocation of
s.checkPermission method with
RuntimePermission("accessDeclaredMembers")
denies access to the declared constructor
- the caller's class loader is not the same as or an
ancestor of the class loader for the current class and
invocation of s.checkPackageAccess() denies access to the package
of this class
Since:
1.1
Finds a resource with a given name.
If this class is in a named Module then this method
will attempt to find the resource in the module. This is done by
delegating to the module's class loader findResource(String,String)
method, invoking it with the module name and the absolute name of the
resource. Resources in named modules are subject to the rules for
encapsulation specified in the Module getResourceAsStream method and so this
method returns null when the resource is a
non-".class" resource in a package that is not open to the
caller's module.
Otherwise, if this class is not in a named module then the rules for
searching resources associated with a given class are implemented by the
defining class loader of the class. This method
delegates to this Class object's class loader.
If this Class object was loaded by the bootstrap class loader,
the method delegates to ClassLoader.getSystemResourceAsStream(String).
Before delegation, an absolute resource name is constructed from the
given resource name using this algorithm:
Parameters:
name - name of the desired resource
Returns:
A
InputStream object;
null if no
resource with this name is found, the resource is in a package
that is not
open to at
least the caller module, or access to the resource is denied
by the security manager.
Throws:
Since:
1.1
See Also:
Finds a resource with a given name.
If this class is in a named Module then this method
will attempt to find the resource in the module. This is done by
delegating to the module's class loader findResource(String,String)
method, invoking it with the module name and the absolute name of the
resource. Resources in named modules are subject to the rules for
encapsulation specified in the Module getResourceAsStream method and so this
method returns null when the resource is a
non-".class" resource in a package that is not open to the
caller's module.
Otherwise, if this class is not in a named module then the rules for
searching resources associated with a given class are implemented by the
defining class loader of the class. This method
delegates to this Class object's class loader.
If this Class object was loaded by the bootstrap class loader,
the method delegates to ClassLoader.getSystemResource(String).
Before delegation, an absolute resource name is constructed from the
given resource name using this algorithm:
Parameters:
name - name of the desired resource
Returns:
A
URL object;
null if no resource with
this name is found, the resource cannot be located by a URL, the
resource is in a package that is not
open to at least the caller
module, or access to the resource is denied by the security
manager.
Throws:
Since:
1.1
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.
Returns:
the ProtectionDomain of this class
Throws:
SecurityException - if a security manager exists and its
checkPermission method doesn't allow
getting the ProtectionDomain.
Since:
1.2
See Also:
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.
Returns:
the desired assertion status of the specified class.
Since:
1.4
See Also:
Returns true if and only if this class was declared as an enum in the
source code.
Note that
Enum is not itself an enum class.
Also note that if an enum constant is declared with a class body,
the class of that enum constant object is an anonymous class
and
not the class of the declaring enum class. The
Enum.getDeclaringClass() method of an enum constant can
be used to get the class of the enum class declaring the
constant.
Returns:
true if and only if this class was declared as an enum in the
source code
Since:
1.5
public boolean isRecord |
() |
Returns
true if and only if this class is a record class.
The direct superclass of a record
class is java.lang.Record. A record class is final. A record class has (possibly zero) record
components; getRecordComponents() returns a non-null but
possibly empty value for a record.
Note that class Record is not a record class and thus
invoking this method on class Record returns false.
Returns:
true if and only if this class is a record class, otherwise false
Since:
16
public T[] getEnumConstants |
() |
Returns the elements of this enum class or null if this
Class object does not represent an enum class.
Returns:
an array containing the values comprising the enum class
represented by this Class object in the order they're
declared, or null if this Class object does not
represent an enum class
Since:
1.5
Casts an object to the class or interface represented
by this
Class object.
Parameters:
obj - the object to be cast
Returns:
the object after casting, or null if obj is null
Throws:
Since:
1.5
public < U> Class<? extends U> asSubclass |
|
Casts this
Class object to represent a subclass of the class
represented by the specified class object. Checks 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).
Type Parameters:
U - the type to cast this
Class object to
Parameters:
clazz - the class of the type to cast this Class object to
Returns:
this Class object, cast to represent a subclass of
the specified class object.
Throws:
ClassCastException - if this
Class object does not
represent a subclass of the specified class (here "subclass" includes
the class itself).
Since:
1.5
Returns this element's annotation for the specified type if
such an annotation is
present, else null.
Note that any annotation returned by this method is a
declaration annotation.
Specified by:
Type Parameters:
A - the type of the annotation to query for and return if present
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:
Since:
1.5
public boolean isAnnotationPresent |
|
Returns true if an annotation for the specified type
is
present on this element, else false. This method
is designed primarily for convenient access to marker annotations.
The truth value returned by this method is equivalent to:
getAnnotation(annotationClass) != null
Specified by:
Parameters:
annotationClass - the Class object corresponding to the
annotation type
Returns:
true if an annotation for the specified annotation
type is present on this element, else false
Throws:
Since:
1.5
Returns annotations that are
associated with this element.
If there are no annotations
associated with this element, the return
value is an array of length 0.
The difference between this method and
AnnotatedElement.getAnnotation(Class)
is that this method detects if its argument is a
repeatable
annotation type (JLS {@jls 9.6}), and if so, attempts to find one or
more annotations of that type by "looking through" a container
annotation.
The caller of this method is free to modify the returned array; it will
have no effect on the arrays returned to other callers.
Note that any annotations returned by this method are
declaration annotations.
Specified by:
Type Parameters:
A - the type of the annotation to query for and return if present
Parameters:
annotationClass - the Class object corresponding to the
annotation type
Returns:
all this element's annotations for the specified annotation type if
associated with this element, else an array of length zero
Throws:
Since:
1.8
Returns annotations that are
present on this element.
If there are no annotations
present on this element, the return
value is an array of length 0.
The caller of this method is free to modify the returned array; it will
have no effect on the arrays returned to other callers.
Note that any annotations returned by this method are
declaration annotations.
Specified by:
Returns:
annotations present on this element
Since:
1.5
Returns this element's annotation for the specified type if
such an annotation is
directly present, else null.
This method ignores inherited annotations. (Returns null if no
annotations are directly present on this element.)
Note that any annotation returned by this method is a
declaration annotation.
Specified by:
Type Parameters:
A - the type of the annotation to query for and return if directly present
Parameters:
annotationClass - the Class object corresponding to the
annotation type
Returns:
this element's annotation for the specified annotation type if
directly present on this element, else null
Throws:
Since:
1.8
getDeclaredAnnotationsByType
public < A extends Annotation> A[] getDeclaredAnnotationsByType |
|
Returns this element's annotation(s) for the specified type if
such annotations are either
directly present or
indirectly present. This method ignores inherited
annotations.
If there are no specified annotations directly or indirectly
present on this element, the return value is an array of length
0.
The difference between this method and
AnnotatedElement.getDeclaredAnnotation(Class) is that this method detects if its
argument is a
repeatable annotation type (JLS {@jls 9.6}), and if so,
attempts to find one or more annotations of that type by "looking
through" a container annotation if one is present.
The caller of this method is free to modify the returned array; it will
have no effect on the arrays returned to other callers.
Note that any annotations returned by this method are
declaration annotations.
Specified by:
Type Parameters:
A - the type of the annotation to query for and return
if directly or indirectly present
Parameters:
annotationClass - the Class object corresponding to the
annotation type
Returns:
all this element's annotations for the specified annotation type if
directly or indirectly present on this element, else an array of length zero
Throws:
Since:
1.8
Returns annotations that are
directly present on this element.
This method ignores inherited annotations.
If there are no annotations
directly present on this element,
the return value is an array of length 0.
The caller of this method is free to modify the returned array; it will
have no effect on the arrays returned to other callers.
Note that any annotations returned by this method are
declaration annotations.
Specified by:
Returns:
annotations directly present on this element
Since:
1.5
Returns an
AnnotatedType object that represents the use of a
type to specify the superclass of the entity represented by this
Class object. (The
use of type Foo to specify the superclass
in '... extends Foo' is distinct from the
declaration of class
Foo.)
If this Class object represents a class whose declaration
does not explicitly indicate an annotated superclass, then the return
value is an AnnotatedType object representing an element with no
annotations.
If this Class represents either the Object class, an
interface type, an array type, a primitive type, or void, the return
value is null.
Returns:
an object representing the superclass
Since:
1.8
Returns an array of
AnnotatedType objects that represent the use
of types to specify superinterfaces of the entity represented by this
Class object. (The
use of type Foo to specify a
superinterface in '... implements Foo' is distinct from the
declaration of interface Foo.)
If this Class object represents a class, the return value is
an array containing objects representing the uses of interface types to
specify interfaces implemented by the class. The order of the objects in
the array corresponds to the order of the interface types used in the
'implements' clause of the declaration of this Class object.
If this Class object represents an interface, the return
value is an array containing objects representing the uses of interface
types to specify interfaces directly extended by the interface. The
order of the objects in the array corresponds to the order of the
interface types used in the 'extends' clause of the declaration of this
Class object.
If this Class object represents a class or interface whose
declaration does not explicitly indicate any annotated superinterfaces,
the return value is an array of length 0.
If this Class object represents either the Object
class, an array type, a primitive type, or void, the return value is an
array of length 0.
Returns:
an array representing the superinterfaces
Since:
1.8
public Class<?> getNestHost |
() |
Returns the nest host of the
nest to which the class
or interface represented by this
Class object belongs.
Every class and interface belongs to exactly one nest.
If the nest host of this class or interface has previously
been determined, then this method returns the nest host.
If the nest host of this class or interface has
not previously been determined, then this method determines the nest
host using the algorithm of JVMS 5.4.4, and returns it.
Often, a class or interface belongs to a nest consisting only of itself,
in which case this method returns
this to indicate that the class
or interface is the nest host.
If this Class object represents a primitive type, an array type,
or void, then this method returns this,
indicating that the represented entity belongs to the nest consisting only of
itself, and is the nest host.
Returns:
the nest host of this class or interface
Throws:
SecurityException - If the returned class is not the current class, and
if a security manager,
s, is present and the caller's
class loader is not the same as or an ancestor of the class
loader for the returned class and invocation of
s.checkPackageAccess()
denies access to the package of the returned class
Since:
11
public boolean isNestmateOf |
|
Determines if the given
Class is a nestmate of the
class or interface represented by this
Class object.
Two classes or interfaces are nestmates
if they have the same
nest host.
Parameters:
c - the class to check
Returns:
true if this class and c are members of
the same nest; and false otherwise.
Since:
11
public Class<?>[] getNestMembers |
() |
Returns an array containing
Class objects representing all the
classes and interfaces that are members of the nest to which the class
or interface represented by this
Class object belongs.
First, this method obtains the
nest host,
H, of the nest to which the class or interface represented by
this
Class object belongs. The zeroth element of the returned
array is
H.
Then, for each class or interface
C which is recorded by
H
as being a member of its nest, this method attempts to obtain the
Class
object for
C (using
the defining class
loader of the current
Class object), and then obtains the
nest host of the nest to which
C belongs.
The classes and interfaces which are recorded by
H as being members
of its nest, and for which
H can be determined as their nest host,
are indicated by subsequent elements of the returned array. The order of
such elements is unspecified. Duplicates are permitted.
If this Class object represents a primitive type, an array type,
or void, then this method returns a single-element array containing
this.
Returns:
an array of all classes and interfaces in the same nest as
this class or interface
Throws:
SecurityException - If any returned class is not the current class, and
if a security manager,
s, is present and the caller's
class loader is not the same as or an ancestor of the class
loader for that returned class and invocation of
s.checkPackageAccess()
denies access to the package of that returned class
Since:
11
See Also:
public String descriptorString |
() |
Returns the descriptor string of the entity (class, interface, array class,
primitive type, or
void) represented by this
Class object.
If this Class object represents a class or interface,
not an array class, then:
- If the class or interface is not hidden,
then the result is a field descriptor (JVMS {@jvms 4.3.2})
for the class or interface. Calling
ClassDesc::ofDescriptor
with the result descriptor string produces a ClassDesc
describing this class or interface.
- If the class or interface is hidden,
then the result is a string of the form:
"L" + N + "." + <suffix> + ";"
where N is the binary name
encoded in internal form indicated by the class file passed to
Lookup::defineHiddenClass, and <suffix> is an unqualified name.
A hidden class or interface has no nominal descriptor.
The result string is not a type descriptor.
If this Class object represents an array class, then
the result is a string consisting of one or more '[' characters
representing the depth of the array nesting, followed by the
descriptor string of the element type.
- If the element type is not a hidden class
or interface, then this array class can be described nominally.
Calling ClassDesc::ofDescriptor
with the result descriptor string produces a ClassDesc
describing this array class.
- If the element type is a hidden class or
interface, then this array class cannot be described nominally.
The result string is not a type descriptor.
If this Class object represents a primitive type or
void, then the result is a field descriptor string which
is a one-letter code corresponding to a primitive type or void
("B", "C", "D", "F", "I", "J", "S", "Z", "V") (JVMS {@jvms 4.3.2}).
Specified by:
Returns:
the descriptor string for this Class object
Since:
12
public Class<?> componentType |
() |
Returns the component type of this
Class, if it describes
an array type, or
null otherwise.
Implementation Requirements:
Specified by:
Returns:
a Class describing the component type, or null
if this Class does not describe an array type
Since:
12
public Class<?> arrayType |
() |
Returns a
Class for an array type whose component type
is described by this
Class.
Specified by:
Returns:
a Class describing the array type
Since:
12
Returns a nominal descriptor for this instance, if one can be
constructed, or an empty
Optional if one cannot be.
Specified by:
Returns:
An
Optional containing the resulting nominal descriptor,
or an empty
Optional if one cannot be constructed.
Since:
12
public boolean isHidden |
() |
Returns
true if and only if the underlying class is a hidden class.
Returns:
true if and only if this class is a hidden class.
Since:
15
See Also:
MethodHandles.Lookup#defineHiddenClass
public Class<?>[] getPermittedSubclasses |
() |
Returns an array containing
Class objects representing the
direct subinterfaces or subclasses permitted to extend or
implement this class or interface if it is sealed. The order of such elements
is unspecified. The array is empty if this sealed class or interface has no
permitted subclass. If this
Class object represents a primitive type,
void, an array type, or a class or interface that is not sealed,
that is
isSealed() returns
false, then this method returns
null.
Conversely, if
isSealed() returns
true, then this method
returns a non-null value.
For each class or interface
C which is recorded as a permitted
direct subinterface or subclass of this class or interface,
this method attempts to obtain the
Class
object for
C (using
the defining class
loader of the current
Class object).
The
Class objects which can be obtained and which are direct
subinterfaces or subclasses of this class or interface,
are indicated by elements of the returned array. If a
Class object
cannot be obtained, it is silently ignored, and not included in the result
array.
Returns:
an array of Class objects of the permitted subclasses of this class or interface,
or null if this class or interface is not sealed.
Throws:
SecurityException - If a security manager,
s, is present and the caller's
class loader is not the same as or an ancestor of the class
loader for that returned class and invocation of
s.checkPackageAccess()
denies access to the package of any class in the returned array.
Since:
17
public boolean isSealed |
() |
Returns
true if and only if this
Class object represents
a sealed class or interface. If this
Class object represents a
primitive type,
void, or an array type, this method returns
false. A sealed class or interface has (possibly zero) permitted
subclasses;
getPermittedSubclasses() returns a non-null but
possibly empty value for a sealed class or interface.
Returns:
true if and only if this Class object represents
a sealed class or interface.
Since:
17
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