Class
class Class<T : Any!> : Serializable, GenericDeclaration, Type, AnnotatedElement, TypeDescriptor.OfField<Class<*>!>
kotlin.Any | |
↳ | java.lang.Class |
Instances of the 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 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 are also represented as 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. A few characteristics are determined by the class loading environment at run time.
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()); }
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.
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.
Summary
Public methods | |
---|---|
Class<*> |
Returns a |
Class<out U> |
asSubclass(clazz: Class<U>) Casts this |
T? |
Casts an object to the class or interface represented by this |
Class<*>? |
Returns the component type of this |
String |
Returns the descriptor string of the entity (class, interface, array class, primitive type, or |
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. |
static Class<*> |
Returns the |
static Class<*> |
forName(name: String, initialize: Boolean, loader: ClassLoader?) Returns the |
A? |
getAnnotation(annotationClass: Class<A>) Returns this element's annotation for the specified type if such an annotation is present, else null. |
Array<Annotation!> |
Returns annotations that are present on this element. |
Array<A> |
getAnnotationsByType(annotationClass: Class<A>) Returns annotations that are associated with this element. |
String? |
Returns the canonical name of the underlying class as defined by The Java Language Specification. |
ClassLoader? |
Returns the class loader for the class. |
Array<Class<*>!> |
Returns an array containing |
Class<*>? |
Returns the |
Constructor<T> |
getConstructor(vararg parameterTypes: Class<*>!) Returns a |
Array<Constructor<*>!> |
Returns an array containing |
A? |
getDeclaredAnnotation(annotationClass: Class<A>) Returns this element's annotation for the specified type if such an annotation is directly present, else null. |
Array<Annotation!> |
Returns annotations that are directly present on this element. |
Array<A> |
getDeclaredAnnotationsByType(annotationClass: Class<A>) Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present. |
Array<Class<*>!> |
Returns an array of |
Constructor<T> |
getDeclaredConstructor(vararg parameterTypes: Class<*>!) Returns a |
Array<Constructor<*>!> |
Returns an array of |
Field |
getDeclaredField(name: String) Returns a |
Array<Field!> |
Returns an array of |
Method |
getDeclaredMethod(name: String, vararg parameterTypes: Class<*>!) Returns a |
Array<Method!> |
Returns an array containing |
Class<*>? |
If the class or interface represented by this |
Class<*>? |
Returns the immediately enclosing class of the underlying class. |
Constructor<*>? |
If this |
Method? |
If this |
Array<T>? |
Returns the elements of this enum class or null if this Class object does not represent an enum class. |
Field |
Returns a |
Array<Field!> |
Returns an array containing |
Array<Type!> |
Returns the |
Type? |
Returns the |
Array<Class<*>!> |
Returns the interfaces directly implemented by the class or interface represented by this object. |
Method |
Returns a |
Array<Method!> |
Returns an array containing |
Int |
Returns the Java language modifiers for this class or interface, encoded in an integer. |
String |
getName() Returns the name of the entity (class, interface, array class, primitive type, or void) represented by this |
Class<*> |
Returns the nest host of the nest to which the class or interface represented by this |
Array<Class<*>!> |
Returns an array containing |
Package? |
Gets the package of this class. |
String |
Returns the fully qualified package name. |
Array<Class<*>!>? |
Returns an array containing |
ProtectionDomain? |
Returns the |
Array<RecordComponent!>? |
Returns an array of |
URL? |
getResource(name: String) Finds a resource with a given name. |
InputStream? |
getResourceAsStream(name: String) Finds a resource with a given name. |
Array<Any!>? |
Gets the signers of this class. |
String |
Returns the simple name of the underlying class as given in the source code. |
Class<in T>? |
Returns the |
String |
Return an informative string for the name of this class or interface. |
Array<TypeVariable<Class<T>!>!> |
Returns an array of |
Boolean |
Returns true if this |
Boolean |
isAnnotationPresent(annotationClass: Class<out Annotation!>) Returns true if an annotation for the specified type is present on this element, else false. |
Boolean |
Returns |
Boolean |
isArray() Determines if this |
Boolean |
isAssignableFrom(cls: Class<*>) Determines if the class or interface represented by this |
Boolean |
isEnum() Returns true if and only if this class was declared as an enum in the source code. |
Boolean |
isInstance(obj: Any?) Determines if the specified |
Boolean |
Determines if this |
Boolean |
Returns |
Boolean |
Returns |
Boolean |
isNestmateOf(c: Class<*>) Determines if the given |
Boolean |
Determines if the specified |
Boolean |
isRecord() Returns |
Boolean |
isSealed() Returns |
Boolean |
{@return {@code true} if and only if this class has the synthetic modifier * bit set} |
T |
Creates a new instance of the class represented by this |
String |
Returns a string describing this |
String |
toString() Converts the object to a string. |
Public methods
arrayType
fun arrayType(): Class<*>
Returns a Class
for an array type whose component type is described by this Class.
Return | |
---|---|
Class<*> |
a Class describing the array type |
asSubclass
fun <U : Any!> asSubclass(clazz: Class<U>): Class<out U>
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).
Parameters | |
---|---|
<U> |
the type to cast this Class object to |
clazz |
Class<U>: the class of the type to cast this Class object to |
Return | |
---|---|
Class<out U> |
this Class object, cast to represent a subclass of the specified class object. |
Exceptions | |
---|---|
java.lang.ClassCastException |
if this Class object does not represent a subclass of the specified class (here "subclass" includes the class itself). |
cast
fun cast(obj: Any?): T?
Casts an object to the class or interface represented by this Class
object.
Parameters | |
---|---|
obj |
Any?: the object to be cast |
Return | |
---|---|
T? |
the object after casting, or null if obj is null |
Exceptions | |
---|---|
java.lang.ClassCastException |
if the object is not null and is not assignable to the type T. |
componentType
fun componentType(): Class<*>?
Returns the component type of this Class
, if it describes an array type, or null
otherwise.
Return | |
---|---|
Class<*>? |
a Class describing the component type, or null if this Class does not describe an array type |
descriptorString
fun descriptorString(): String
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:
- The result is a field descriptor (JVMS {@jvms 4.3.2}) for the class or interface.
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.
- This array class can be described nominally.
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}).
Return | |
---|---|
String |
the descriptor string for this Class object |
desiredAssertionStatus
fun desiredAssertionStatus(): 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. 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.
Return | |
---|---|
Boolean |
the desired assertion status of the specified class. |
forName
static fun forName(className: String): Class<*>
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 |
String: the fully qualified name of the desired class. |
Return | |
---|---|
Class<*> |
the Class object for the class with the specified name. |
Exceptions | |
---|---|
java.lang.LinkageError |
if the linkage fails |
java.lang.ExceptionInInitializerError |
if the initialization provoked by this method fails |
java.lang.ClassNotFoundException |
if the class cannot be located |
forName
static fun forName(
name: String,
initialize: Boolean,
loader: ClassLoader?
): Class<*>
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 |
String: fully qualified name of the desired class |
initialize |
Boolean: if true the class will be initialized (which implies linking). See Section {@jls * 12.4} of The Java Language Specification. |
loader |
ClassLoader?: class loader from which the class must be loaded |
Return | |
---|---|
Class<*> |
class object representing the desired class |
Exceptions | |
---|---|
java.lang.LinkageError |
if the linkage fails |
java.lang.ExceptionInInitializerError |
if the initialization provoked by this method fails |
java.lang.ClassNotFoundException |
if the class cannot be located by the specified class loader |
getAnnotation
fun <A : Annotation!> getAnnotation(annotationClass: Class<A>): A?
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.
Parameters | |
---|---|
<T> |
the type of the annotation to query for and return if present |
annotationClass |
Class<A>: the Class object corresponding to the annotation type |
Return | |
---|---|
A? |
this element's annotation for the specified annotation type if present on this element, else null |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the given annotation class is null |
getAnnotations
fun getAnnotations(): Array<Annotation!>
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.
Return | |
---|---|
Array<Annotation!> |
annotations present on this element |
getAnnotationsByType
fun <A : Annotation!> getAnnotationsByType(annotationClass: Class<A>): Array<A>
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 getAnnotation(java.lang.Class)
is that this method detects if its argument is a repeatable annotation type (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.
Parameters | |
---|---|
<T> |
the type of the annotation to query for and return if present |
annotationClass |
Class<A>: the Class object corresponding to the annotation type |
Return | |
---|---|
Array<A> |
all this element's annotations for the specified annotation type if associated with this element, else an array of length zero |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the given annotation class is null |
getCanonicalName
fun getCanonicalName(): String?
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:
- a local class
- a anonymous class
- an array whose component type does not have a canonical name
Return | |
---|---|
String? |
the canonical name of the underlying class if it exists, and null otherwise. |
getClassLoader
fun getClassLoader(): ClassLoader?
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.
Return | |
---|---|
ClassLoader? |
the class loader that loaded the class or interface represented by this Class object. |
getClasses
fun getClasses(): Array<Class<*>!>
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.
Return | |
---|---|
Array<Class<*>!> |
the array of Class objects representing the public members of this class |
getComponentType
fun getComponentType(): Class<*>?
Returns the Class
representing the component type of an array. If this class does not represent an array class this method returns null.
Return | |
---|---|
Class<*>? |
the Class representing the component type of this class if this class is an array |
See Also
getConstructor
fun getConstructor(vararg parameterTypes: Class<*>!): Constructor<T>
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 |
Class<*>!: the parameter array |
Return | |
---|---|
Constructor<T> |
the Constructor object of the public constructor that matches the specified parameterTypes |
Exceptions | |
---|---|
java.lang.NoSuchMethodException |
if a matching method is not found. |
java.lang.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. |
getConstructors
fun getConstructors(): Array<Constructor<*>!>
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.
Return | |
---|---|
Array<Constructor<*>!> |
the array of Constructor objects representing the public constructors of this class |
Exceptions | |
---|---|
java.lang.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. |
getDeclaredAnnotation
fun <A : Annotation!> getDeclaredAnnotation(annotationClass: Class<A>): A?
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.
Parameters | |
---|---|
<T> |
the type of the annotation to query for and return if directly present |
annotationClass |
Class<A>: the Class object corresponding to the annotation type |
Return | |
---|---|
A? |
this element's annotation for the specified annotation type if directly present on this element, else null |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the given annotation class is null |
getDeclaredAnnotations
fun getDeclaredAnnotations(): Array<Annotation!>
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.
Return | |
---|---|
Array<Annotation!> |
annotations directly present on this element |
getDeclaredAnnotationsByType
fun <A : Annotation!> getDeclaredAnnotationsByType(annotationClass: Class<A>): Array<A>
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 getDeclaredAnnotation(java.lang.Class)
is that this method detects if its argument is a repeatable annotation type (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.
Parameters | |
---|---|
<T> |
the type of the annotation to query for and return if directly or indirectly present |
annotationClass |
Class<A>: the Class object corresponding to the annotation type |
Return | |
---|---|
Array<A> |
all this element's annotations for the specified annotation type if directly or indirectly present on this element, else an array of length zero |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the given annotation class is null |
getDeclaredClasses
fun getDeclaredClasses(): Array<Class<*>!>
Returns an array of Class
objects reflecting all the classes and interfaces declared as members of the class represented by this Class
object. This includes public, protected, default (package) access, and private classes and interfaces declared by the class, but excludes inherited classes and interfaces. This method returns an array of length 0 if the class declares no classes or interfaces as members, or if this Class
object represents a primitive type, an array class, or void.
Return | |
---|---|
Array<Class<*>!> |
the array of Class objects representing all the declared members of this class |
Exceptions | |
---|---|
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredConstructor
fun getDeclaredConstructor(vararg parameterTypes: Class<*>!): Constructor<T>
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 |
Class<*>!: the parameter array |
Return | |
---|---|
Constructor<T> |
The Constructor object for the constructor with the specified parameter list |
Exceptions | |
---|---|
java.lang.NoSuchMethodException |
if a matching method is not found. |
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredConstructors
fun getDeclaredConstructors(): Array<Constructor<*>!>
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}.
Return | |
---|---|
Array<Constructor<*>!> |
the array of Constructor objects representing all the declared constructors of this class |
Exceptions | |
---|---|
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredField
fun getDeclaredField(name: String): Field
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 |
String: the name of the field |
Return | |
---|---|
Field |
the Field object for the specified field in this class |
Exceptions | |
---|---|
java.lang.NoSuchFieldException |
if a field with the specified name is not found. |
java.lang.NullPointerException |
if name is null |
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredFields
fun getDeclaredFields(): Array<Field!>
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.
Return | |
---|---|
Array<Field!> |
the array of Field objects representing all the declared fields of this class |
Exceptions | |
---|---|
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredMethod
fun getDeclaredMethod(
name: String,
vararg parameterTypes: Class<*>!
): Method
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 |
String: the name of the method |
parameterTypes |
Class<*>!: the parameter array |
Return | |
---|---|
Method |
the Method object for the method of this class matching the specified name and parameters |
Exceptions | |
---|---|
java.lang.NoSuchMethodException |
if a matching method is not found. |
java.lang.NullPointerException |
if name is null |
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getDeclaredMethods
fun getDeclaredMethods(): Array<Method!>
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.
Return | |
---|---|
Array<Method!> |
the array of Method objects representing all the declared methods of this class |
Exceptions | |
---|---|
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
See Also
getDeclaringClass
fun getDeclaringClass(): Class<*>?
If the class or interface represented by this Class
object is a member of another class, returns the Class
object representing the class in which it was declared. This method returns null if this class or interface is not a member of any other class. If this Class
object represents an array class, a primitive type, or void,then this method returns null.
Return | |
---|---|
Class<*>? |
the declaring class for this class |
getEnclosingClass
fun getEnclosingClass(): Class<*>?
Returns the immediately enclosing class of the underlying class. If the underlying class is a top level class this method returns null
.
Return | |
---|---|
Class<*>? |
the immediately enclosing class of the underlying class |
getEnclosingConstructor
fun getEnclosingConstructor(): Constructor<*>?
If this Class
object represents a local or anonymous class within a constructor, returns a 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.
Return | |
---|---|
Constructor<*>? |
the immediately enclosing constructor of the underlying class, if that class is a local or anonymous class; otherwise null . |
getEnclosingMethod
fun getEnclosingMethod(): Method?
If this Class
object represents a local or anonymous class within a method, returns a 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.
Return | |
---|---|
Method? |
the immediately enclosing method of the underlying class, if that class is a local or anonymous class; otherwise null . |
getEnumConstants
fun getEnumConstants(): Array<T>?
Returns the elements of this enum class or null if this Class object does not represent an enum class.
Return | |
---|---|
Array<T>? |
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 |
getField
fun getField(name: String): Field
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 |
String: the field name |
Return | |
---|---|
Field |
the Field object of this class specified by name |
Exceptions | |
---|---|
java.lang.NoSuchFieldException |
if a field with the specified name is not found. |
java.lang.NullPointerException |
if name is null |
java.lang.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. |
getFields
fun getFields(): Array<Field!>
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.
Return | |
---|---|
Array<Field!> |
the array of Field objects representing the public fields |
Exceptions | |
---|---|
java.lang.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. |
getGenericInterfaces
fun getGenericInterfaces(): Array<Type!>
Returns the Type
s 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.
Return | |
---|---|
Array<Type!> |
an array of interfaces directly implemented by this class |
Exceptions | |
---|---|
java.lang.reflect.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 |
java.lang.TypeNotPresentException |
if any of the generic superinterfaces refers to a non-existent type declaration |
java.lang.reflect.MalformedParameterizedTypeException |
if any of the generic superinterfaces refer to a parameterized type that cannot be instantiated for any reason |
getGenericSuperclass
fun getGenericSuperclass(): Type?
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 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.
Return | |
---|---|
Type? |
the direct superclass of the class represented by this Class object |
Exceptions | |
---|---|
java.lang.reflect.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 |
java.lang.TypeNotPresentException |
if the generic superclass refers to a non-existent type declaration |
java.lang.reflect.MalformedParameterizedTypeException |
if the generic superclass refers to a parameterized type that cannot be instantiated for any reason |
getInterfaces
fun getInterfaces(): Array<Class<*>!>
Returns the interfaces directly implemented by the class or interface represented by this 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.
Return | |
---|---|
Array<Class<*>!> |
an array of interfaces directly implemented by this class |
getMethod
fun getMethod(
name: String,
vararg parameterTypes: Class<*>!
): Method
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 givenname
andparameterTypes
- 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.
- C's declared public instance and static methods as returned by
- 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
(S.class).
Parameters | |
---|---|
name |
String: the name of the method |
parameterTypes |
Class<*>!: the list of parameters |
Return | |
---|---|
Method |
the Method object that matches the specified name and parameterTypes |
Exceptions | |
---|---|
java.lang.NoSuchMethodException |
if a matching method is not found or if the name is "<init>"or "<clinit>". |
java.lang.NullPointerException |
if name is null |
java.lang.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. |
getMethods
fun getMethods(): Array<Method!>
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.
- C's declared public instance and static methods as returned by
- 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.
Return | |
---|---|
Array<Method!> |
the array of Method objects representing the public methods of this class |
Exceptions | |
---|---|
java.lang.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. |
getModifiers
fun getModifiers(): Int
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.
Return | |
---|---|
Int |
the int representing the modifiers for this class |
See Also
getName
fun getName(): String
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 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 Type | Encoding |
---|---|
boolean |
Z |
byte |
B |
char |
C |
class or interface with binary name N | L N; |
double |
D |
float |
F |
int |
I |
long |
J |
short |
S |
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"
Return | |
---|---|
String |
the name of the class, interface, or other entity represented by this Class object. |
getNestHost
fun getNestHost(): Class<*>
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.
Return | |
---|---|
Class<*> |
the nest host of this class or interface |
getNestMembers
fun getNestMembers(): Array<Class<*>!>
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 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
.
Return | |
---|---|
Array<Class<*>!> |
an array of all classes and interfaces in the same nest as this class or interface |
See Also
getPackage
fun getPackage(): Package?
Gets the package of this class.
If this class represents an array type, a primitive type or void, this method returns null
.
Return | |
---|---|
Package? |
the package of this class. |
getPackageName
fun getPackageName(): String
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.
Return | |
---|---|
String |
the fully qualified package name |
getPermittedSubclasses
fun getPermittedSubclasses(): Array<Class<*>!>?
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 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.
Return | |
---|---|
Array<Class<*>!>? |
an array of Class objects of the permitted subclasses of this class or interface, or null if this class or interface is not sealed. |
getProtectionDomain
fun getProtectionDomain(): ProtectionDomain?
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
.
Return | |
---|---|
ProtectionDomain? |
the ProtectionDomain of this class |
Exceptions | |
---|---|
java.lang.SecurityException |
if a security manager exists and its checkPermission method doesn't allow getting the ProtectionDomain. |
getRecordComponents
fun getRecordComponents(): Array<RecordComponent!>?
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.
Return | |
---|---|
Array<RecordComponent!>? |
An array of RecordComponent objects representing all the record components of this record class, or null if this class is not a record class |
Exceptions | |
---|---|
java.lang.SecurityException |
If a security manager, s, is present and any of the following conditions is met:
|
getResource
fun getResource(name: String): URL?
Finds a resource with a given name.
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
.
Before delegation, an absolute resource name is constructed from the given resource name using this algorithm:
- If the
name
begins with a'/'
('\u002f'
), then the absolute name of the resource is the portion of thename
following the'/'
. - Otherwise, the absolute name is of the following form:
modified_package_name/name
Where the
modified_package_name
is the package name of this object with'/'
substituted for'.'
('\u002e'
).
Parameters | |
---|---|
name |
String: name of the desired resource |
Return | |
---|---|
URL? |
A java.net.URL object; null if no resource with this name is found. |
Exceptions | |
---|---|
java.lang.NullPointerException |
If name is null |
getResourceAsStream
fun getResourceAsStream(name: String): InputStream?
Finds a resource with a given name.
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
.
Before delegation, an absolute resource name is constructed from the given resource name using this algorithm:
- If the
name
begins with a'/'
('\u002f'
), then the absolute name of the resource is the portion of thename
following the'/'
. - Otherwise, the absolute name is of the following form:
modified_package_name/name
Where the
modified_package_name
is the package name of this object with'/'
substituted for'.'
('\u002e'
).
Parameters | |
---|---|
name |
String: name of the desired resource |
Return | |
---|---|
InputStream? |
A java.io.InputStream object; null if no resource with this name is found. |
Exceptions | |
---|---|
java.lang.NullPointerException |
If name is null |
getSigners
fun getSigners(): Array<Any!>?
Gets the signers of this class.
Return | |
---|---|
Array<Any!>? |
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. |
getSimpleName
fun getSimpleName(): String
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 "[]".
Return | |
---|---|
String |
the simple name of the underlying class |
getSuperclass
fun getSuperclass(): Class<in T>?
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.
Return | |
---|---|
Class<in T>? |
the direct superclass of the class represented by this Class object |
getTypeName
fun getTypeName(): String
Return an informative string for the name of this class or interface.
Return | |
---|---|
String |
an informative string for the name of this class or interface |
getTypeParameters
fun getTypeParameters(): Array<TypeVariable<Class<T>!>!>
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.
Return | |
---|---|
Array<TypeVariable<Class<T>!>!> |
an array of TypeVariable objects that represent the type variables declared by this generic declaration |
Exceptions | |
---|---|
java.lang.reflect.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 |
isAnnotation
fun isAnnotation(): Boolean
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.
Return | |
---|---|
Boolean |
true if this Class object represents an annotation interface; false otherwise |
isAnnotationPresent
fun isAnnotationPresent(annotationClass: Class<out Annotation!>): Boolean
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
The body of the default method is specified to be the code above.
Parameters | |
---|---|
annotationClass |
Class<out Annotation!>: the Class object corresponding to the annotation type |
Return | |
---|---|
Boolean |
true if an annotation for the specified annotation type is present on this element, else false |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the given annotation class is null |
isAnonymousClass
fun isAnonymousClass(): Boolean
Returns true
if and only if the underlying class is an anonymous class.
Return | |
---|---|
Boolean |
true if and only if this class is an anonymous class. |
isArray
fun isArray(): Boolean
Determines if this Class
object represents an array class.
Return | |
---|---|
Boolean |
true if this Class object represents an array class; false otherwise. |
isAssignableFrom
fun isAssignableFrom(cls: Class<*>): 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. 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 |
Class<*>: the Class object to be checked |
Return | |
---|---|
Boolean |
the boolean value indicating whether objects of the type cls can be assigned to objects of this class |
Exceptions | |
---|---|
java.lang.NullPointerException |
if the specified Class parameter is null. |
isEnum
fun isEnum(): Boolean
Returns true if and only if this class was declared as an enum in the source code. Note that java.lang.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.
Return | |
---|---|
Boolean |
true if and only if this class was declared as an enum in the source code |
isInstance
fun isInstance(obj: Any?): Boolean
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 |
Any?: the object to check |
Return | |
---|---|
Boolean |
true if obj is an instance of this class |
isInterface
fun isInterface(): Boolean
Determines if this Class
object represents an interface type.
Return | |
---|---|
Boolean |
true if this Class object represents an interface; false otherwise. |
isLocalClass
fun isLocalClass(): Boolean
Returns true
if and only if the underlying class is a local class.
Return | |
---|---|
Boolean |
true if and only if this class is a local class. |
isMemberClass
fun isMemberClass(): Boolean
Returns true
if and only if the underlying class is a member class.
Return | |
---|---|
Boolean |
true if and only if this class is a member class. |
isNestmateOf
fun isNestmateOf(c: Class<*>): Boolean
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 |
Class<*>: the class to check |
Return | |
---|---|
Boolean |
true if this class and c are members of the same nest; and false otherwise. |
isPrimitive
fun isPrimitive(): Boolean
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
.
Return | |
---|---|
Boolean |
true if and only if this class represents a primitive type |
isRecord
fun isRecord(): Boolean
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
.
Return | |
---|---|
Boolean |
true if and only if this class is a record class, otherwise false |
isSealed
fun isSealed(): Boolean
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.
Return | |
---|---|
Boolean |
true if and only if this Class object represents a sealed class or interface. |
isSynthetic
fun isSynthetic(): Boolean
{@return {@code true} if and only if this class has the synthetic modifier * bit set}
See Also
newInstance
funnewInstance(): T
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 The call Constructor.newInstance
method avoids this problem by wrapping any exception thrown by the constructor in a (checked) .
<code>clazz.newInstance()
</code>
<code>clazz.getDeclaredConstructor().newInstance()
</code>
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.
Return | |
---|---|
T |
a newly allocated instance of the class represented by this object. |
Exceptions | |
---|---|
java.lang.IllegalAccessException |
if the class or its nullary constructor is not accessible. |
java.lang.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. |
java.lang.ExceptionInInitializerError |
if the initialization provoked by this method fails. |
toGenericString
fun toGenericString(): String
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.
Return | |
---|---|
String |
a string describing this Class , including information about modifiers and type parameters |
toString
fun toString(): String
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
.
Return | |
---|---|
String |
a string representation of this Class object. |