Added in API level 1

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:

• ClassLoader::defineClass

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());
      }
  

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.

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<*>	arrayType() Returns a Class for an array type whose component type is described by this Class.
Class<out U>	asSubclass(clazz: Class<U>) Casts this Class object to represent a subclass of the class represented by the specified class object.
T?	cast(obj: Any?) Casts an object to the class or interface represented by this Class object.
Class<*>?	componentType() Returns the component type of this Class, if it describes an array type, or null otherwise.
String	descriptorString() Returns the descriptor string of the entity (class, interface, array class, primitive type, or void) represented by this Class object.
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.
static Class<*>	forName(className: String) Returns the Class object associated with the class or interface with the given string name.
static Class<*>	forName(name: String, initialize: Boolean, loader: ClassLoader?) Returns the Class object associated with the class or interface with the given string name, using the given class loader.
A?	getAnnotation(annotationClass: Class<A>) Returns this element's annotation for the specified type if such an annotation is present, else null.
Array<Annotation!>	getAnnotations() Returns annotations that are present on this element.
Array<A>	getAnnotationsByType(annotationClass: Class<A>) Returns annotations that are associated with this element.
String?	getCanonicalName() Returns the canonical name of the underlying class as defined by The Java Language Specification.
ClassLoader?	getClassLoader() Returns the class loader for the class.
Array<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.
Class<*>?	getComponentType() Returns the Class representing the component type of an array.
Constructor<T>	getConstructor(vararg parameterTypes: Class<*>!) Returns a Constructor object that reflects the specified public constructor of the class represented by this Class object.
Array<Constructor<*>!>	getConstructors() Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object.
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!>	getDeclaredAnnotations() 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<*>!>	getDeclaredClasses() Returns an array of Class objects reflecting all the classes and interfaces declared as members of the class represented by this Class object.
Constructor<T>	getDeclaredConstructor(vararg parameterTypes: Class<*>!) Returns a Constructor object that reflects the specified constructor of the class or interface represented by this Class object.
Array<Constructor<*>!>	getDeclaredConstructors() Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.
Field	getDeclaredField(name: String) Returns a Field object that reflects the specified declared field of the class or interface represented by this Class object.
Array<Field!>	getDeclaredFields() Returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object.
Method	getDeclaredMethod(name: String, vararg parameterTypes: Class<*>!) Returns a Method object that reflects the specified declared method of the class or interface represented by this Class object.
Array<Method!>	getDeclaredMethods() 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.
Class<*>?	getDeclaringClass() If the class or interface represented by this Class object is a member of another class, returns the Class object representing the class in which it was declared.
Class<*>?	getEnclosingClass() Returns the immediately enclosing class of the underlying class.
Constructor<*>?	getEnclosingConstructor() 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.
Method?	getEnclosingMethod() 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.
Array<T>?	getEnumConstants() Returns the elements of this enum class or null if this Class object does not represent an enum class.
Field	getField(name: String) Returns a Field object that reflects the specified public member field of the class or interface represented by this Class object.
Array<Field!>	getFields() Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object.
Array<Type!>	getGenericInterfaces() Returns the Types representing the interfaces directly implemented by the class or interface represented by this Class object.
Type?	getGenericSuperclass() Returns the Type representing the direct superclass of the entity (class, interface, primitive type or void) represented by this Class object.
Array<Class<*>!>	getInterfaces() Returns the interfaces directly implemented by the class or interface represented by this object.
Method	getMethod(name: String, vararg parameterTypes: Class<*>!) Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object.
Array<Method!>	getMethods() 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.
Int	getModifiers() 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 object.
Class<*>	getNestHost() Returns the nest host of the nest to which the class or interface represented by this Class object belongs.
Array<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.
Package?	getPackage() Gets the package of this class.
String	getPackageName() Returns the fully qualified package name.
Array<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.
ProtectionDomain?	getProtectionDomain() Returns the ProtectionDomain of this class.
Array<RecordComponent!>?	getRecordComponents() 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.
URL?	getResource(name: String) Finds a resource with a given name.
InputStream?	getResourceAsStream(name: String) Finds a resource with a given name.
Array<Any!>?	getSigners() Gets the signers of this class.
String	getSimpleName() Returns the simple name of the underlying class as given in the source code.
Class<in T>?	getSuperclass() Returns the Class representing the direct superclass of the entity (class, interface, primitive type or void) represented by this Class.
String	getTypeName() Return an informative string for the name of this class or interface.
Array<TypeVariable<Class<T>!>!>	getTypeParameters() Returns an array of TypeVariable objects that represent the type variables declared by the generic declaration represented by this GenericDeclaration object, in declaration order.
Boolean	isAnnotation() Returns true if this Class object represents an annotation interface.
Boolean	isAnnotationPresent(annotationClass: Class<out Annotation!>) Returns true if an annotation for the specified type is present on this element, else false.
Boolean	isAnonymousClass() Returns true if and only if the underlying class is an anonymous class.
Boolean	isArray() Determines if this Class object represents an array class.
Boolean	isAssignableFrom(cls: Class<*>) 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.
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 Object is assignment-compatible with the object represented by this Class.
Boolean	isInterface() Determines if this Class object represents an interface type.
Boolean	isLocalClass() Returns true if and only if the underlying class is a local class.
Boolean	isMemberClass() Returns true if and only if the underlying class is a member class.
Boolean	isNestmateOf(c: Class<*>) Determines if the given Class is a nestmate of the class or interface represented by this Class object.
Boolean	isPrimitive() Determines if the specified Class object represents a primitive type.
Boolean	isRecord() Returns true if and only if this class is a record class.
Boolean	isSealed() Returns true if and only if this Class object represents a sealed class or interface.
Boolean	isSynthetic() {@return {@code true} if and only if this class has the synthetic modifier * bit set}
T	newInstance() Creates a new instance of the class represented by this Class object.
String	toGenericString() Returns a string describing this Class, including information about modifiers and type parameters.
String	toString() Converts the object to a string.

Public methods

arrayType

Added in API level 34

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

Added in API level 1

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

Added in API level 1

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

Added in API level 34

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

Added in API level 34

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

Added in API level 1

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.

See Also

• java.lang.ClassLoader#setClassAssertionStatus
• java.lang.ClassLoader#setPackageAssertionStatus
• java.lang.ClassLoader#setDefaultAssertionStatus

forName

Added in API level 1

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

Added in API level 1

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

See Also

• java.lang.Class#forName(String)
• java.lang.ClassLoader

getAnnotation

Added in API level 1

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

Added in API level 1

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

Added in API level 24

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

Added in API level 1

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

Added in API level 1

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.

See Also

• java.lang.ClassLoader
• java.lang.RuntimePermission

getClasses

Added in API level 1

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

Added in API level 1

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

• java.lang.reflect.Array

getConstructor

Added in API level 1

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

Added in API level 1

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

Added in API level 24

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

Added in API level 1

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

Added in API level 24

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

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredConstructor

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredConstructors

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredField

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredFields

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredMethod

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getDeclaredMethods

Added in API level 1

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

See Also

getDeclaringClass

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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:

1. If C declares a public field with the name specified, that is the field to be reflected.
2. 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.
3. 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

Added in API level 1

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

Added in API level 1

fun getGenericInterfaces(): Array<Type!>

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.

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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:

1. A union of methods is composed of:
   1. 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
   2. If C is a class other than Object, then include the result of invoking this algorithm recursively on the superclass of C.
   3. Include the results of invoking this algorithm recursively on all direct superinterfaces of C, but include only instance methods.
2. 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).
3. 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:
   1. N is declared by a class and M is declared by an interface; or
   2. 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).
4. 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

Added in API level 1

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:

1. A union of methods is composed of:
   1. C's declared public instance and static methods as returned by getDeclaredMethods() and filtered to include only public methods.
   2. If C is a class other than Object, then include the result of invoking this algorithm recursively on the superclass of C.
   3. Include the results of invoking this algorithm recursively on all direct superinterfaces of C, but include only instance methods.
2. Union from step 1 is partitioned into subsets of methods with same signature (name, parameter types) and return type.
3. 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:
   1. N is declared by a class and M is declared by an interface; or
   2. 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).
4. 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

Added in API level 1

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

• java.lang.reflect.Modifier

getName

Added in API level 1

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 types and encodings

Element Type	Encoding
boolean	Z
byte	B
char	C
class or interface with binary name N	LN;
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

Added in API level 34

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

Added in API level 34

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

• #getNestHost()

getPackage

Added in API level 1

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

Added in API level 31

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

Added in API level 34

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

Added in API level 1

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.

See Also

• java.security.ProtectionDomain
• java.lang.RuntimePermission

getRecordComponents

Added in API level 34

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: the caller's class loader is not the same as the class loader of this class and invocation of java.lang.SecurityManager#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

getResource

Added in API level 1

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 the name following the '/'.
• Otherwise, the absolute name is of the following form: modified_package_name/name

  Where the modified_package_name is the package name of this object with '/' substituted for '.' ('\u002e').

Parameters
name	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

Added in API level 1

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 the name following the '/'.
• Otherwise, the absolute name is of the following form: modified_package_name/name

  Where the modified_package_name is the package name of this object with '/' substituted for '.' ('\u002e').

Parameters
name	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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 26

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 34

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

Added in API level 1

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

See Also

• java.lang.Boolean#TYPE
• java.lang.Character#TYPE
• java.lang.Byte#TYPE
• java.lang.Short#TYPE
• java.lang.Integer#TYPE
• java.lang.Long#TYPE
• java.lang.Float#TYPE
• java.lang.Double#TYPE
• java.lang.Void#TYPE

isRecord

Added in API level 34

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

Added in API level 34

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

Added in API level 1

fun isSynthetic(): Boolean

{@return {@code true} if and only if this class has the synthetic modifier * bit set}

See Also

newInstance

Added in API level 1
Deprecated in API level 34

fun newInstance(): 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 Constructor.newInstance method avoids this problem by wrapping any exception thrown by the constructor in a (checked) .

The call

<code>clazz.newInstance()
  </code>

can be replaced by

<code>clazz.getDeclaredConstructor().newInstance()
  </code>

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.

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

Added in API level 26

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

Added in API level 1

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.