Added in API level 1

Summary: Methods | Inherited Methods

Class

public final class Class
extends Object implements AnnotatedElement, GenericDeclaration, Serializable, Type, OfField<Class<?>>

java.lang.Object
↳	java.lang.Class<T>

---

Instances of the class Class represent classes and interfaces in a running Java application. An enum class and a record class are kinds of class; an annotation interface is a kind of interface. Every array also belongs to a class that is reflected as a Class object that is shared by all arrays with the same element type and number of dimensions. The primitive Java types (boolean, byte, char, short, int, long, float, and double), and the keyword void are also represented as Class objects.

Class has no public constructor. Instead a Class object is constructed automatically by the Java Virtual Machine when a class is derived from the bytes of a class file through the invocation of one of the following methods:

• 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.

See also:

• ClassLoader.defineClass(byte[], int, int)

Summary

Public methods
Class<?>	arrayType() Returns a Class for an array type whose component type is described by this Class.
<U> Class<? extends U>	asSubclass(Class<U> clazz) Casts this Class object to represent a subclass of the class represented by the specified class object.
T	cast(Object obj) 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(String name, boolean initialize, ClassLoader loader) Returns the Class object associated with the class or interface with the given string name, using the given class loader.
static Class<?>	forName(String className) Returns the Class object associated with the class or interface with the given string name.
<A extends Annotation> A	getAnnotation(Class<A> annotationClass) Note that any annotation returned by this method is a declaration annotation.
Annotation[]	getAnnotations() Returns annotations that are present on this element. Note that any annotations returned by this method are declaration annotations.
<A extends Annotation> A[]	getAnnotationsByType(Class<A> annotationClass) Note that any annotations returned by this method are declaration annotations.
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.
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(Class...<?> parameterTypes) Returns a Constructor object that reflects the specified public constructor of the class represented by this Class object.
Constructor[]<?>	getConstructors() Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object.
<A extends Annotation> A	getDeclaredAnnotation(Class<A> annotationClass) Note that any annotation returned by this method is a declaration annotation.
Annotation[]	getDeclaredAnnotations() Returns annotations that are directly present on this element. Note that any annotations returned by this method are declaration annotations.
<A extends Annotation> A[]	getDeclaredAnnotationsByType(Class<A> annotationClass) Note that any annotations returned by this method are declaration annotations.
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(Class...<?> parameterTypes) Returns a Constructor object that reflects the specified constructor of the class or interface represented by this Class object.
Constructor[]<?>	getDeclaredConstructors() Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.
Field	getDeclaredField(String name) Returns a Field object that reflects the specified declared field of the class or interface represented by this Class object.
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(String name, Class...<?> parameterTypes) Returns a Method object that reflects the specified declared method of the class or interface represented by this Class object.
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 Constructor 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 Method object representing the immediately enclosing method of the underlying class.
T[]	getEnumConstants() Returns the elements of this enum class or null if this Class object does not represent an enum class.
Field	getField(String name) Returns a Field object that reflects the specified public member field of the class or interface represented by this Class object.
Field[]	getFields() Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object.
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.
Class[]<?>	getInterfaces() Returns the interfaces directly implemented by the class or interface represented by this Class object.
Method	getMethod(String name, Class...<?> parameterTypes) Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object.
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.
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.
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.
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(String name) Finds a resource with a given name.
InputStream	getResourceAsStream(String name) Finds a resource with a given name.
Object[]	getSigners() Gets the signers of this class.
String	getSimpleName() Returns the simple name of the underlying class as given in the source code.
Class<? super 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.
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(Class<? extends Annotation> annotationClass) 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(Class<?> cls) Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter.
boolean	isEnum() Returns true if and only if this class was declared as an enum in the source code.
boolean	isInstance(Object obj) 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(Class<?> c) 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()
T	newInstance() This method was deprecated in API level 34. This method propagates any exception thrown by the nullary constructor, including a checked exception. Use of this method effectively bypasses the compile-time exception checking that would otherwise be performed by the compiler. The Constructor.newInstance method avoids this problem by wrapping any exception thrown by the constructor in a (checked) InvocationTargetException. The call clazz.newInstance() can be replaced by clazz.getDeclaredConstructor().newInstance() The latter sequence of calls is inferred to be able to throw the additional exception types InvocationTargetException and NoSuchMethodException. Both of these exception types are subclasses of ReflectiveOperationException.
String	toGenericString() Returns a string describing this Class, including information about modifiers and type parameters.
String	toString() Converts the object to a string.

Inherited methods
From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
From interface java.lang.reflect.AnnotatedElement abstract <T extends Annotation> T getAnnotation(Class<T> annotationClass) Returns this element's annotation for the specified type if such an annotation is present, else null. abstract Annotation[] getAnnotations() Returns annotations that are present on this element. default <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass) Returns annotations that are associated with this element. default <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass) Returns this element's annotation for the specified type if such an annotation is directly present, else null. abstract Annotation[] getDeclaredAnnotations() Returns annotations that are directly present on this element. default <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass) Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present. default boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) Returns true if an annotation for the specified type is present on this element, else false.
From interface java.lang.reflect.GenericDeclaration abstract TypeVariable[]<?> 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.
From interface java.lang.reflect.Type default String getTypeName() Returns a string describing this type, including information about any type parameters.
From interface java.lang.invoke.TypeDescriptor.OfField abstract F arrayType() Return a descriptor for the array type whose component type is described by this descriptor abstract F componentType() If this field descriptor describes an array type, return a descriptor for its component type, otherwise return null. abstract boolean isArray() Does this field descriptor describe an array type? abstract boolean isPrimitive() Does this field descriptor describe a primitive type (including void.)
From interface java.lang.invoke.TypeDescriptor abstract String descriptorString() Returns the descriptor string for this TypeDescriptor object.

Public methods

arrayType

Added in API level 34

public Class<?> arrayType ()

Returns a Class for an array type whose component type is described by this Class.

Returns
Class<?>	a Class describing the array type

asSubclass

Added in API level 1

public Class<? extends U> asSubclass (Class<U> clazz)

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
clazz	Class: the class of the type to cast this Class object to

Returns
Class<? extends U>	this Class object, cast to represent a subclass of the specified class object.

Throws
ClassCastException	if this Class object does not represent a subclass of the specified class (here "subclass" includes the class itself).

cast

Added in API level 1

public T cast (Object obj)

Casts an object to the class or interface represented by this Class object.

Parameters
obj	Object: the object to be cast

Returns
T	the object after casting, or null if obj is null

Throws
ClassCastException	if the object is not null and is not assignable to the type T.

componentType

Added in API level 34

public Class<?> componentType ()

Returns the component type of this Class, if it describes an array type, or null otherwise.

Implementation Requirements:

• Equivalent to Class.getComponentType().

Returns
Class<?>	a Class describing the component type, or null if this Class does not describe an array type

descriptorString

Added in API level 34

public String descriptorString ()

Returns the descriptor string of the entity (class, interface, array class, primitive type, or void) represented by this Class object.

If this Class object represents a class or interface, not an array class, then:

• 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}).

API Note:

• This is not a strict inverse of forName(String); distinct classes which share a common name but have different class loaders will have identical descriptor strings.

Returns
String	the descriptor string for this Class object

desiredAssertionStatus

Added in API level 1

public boolean desiredAssertionStatus ()

Returns the assertion status that would be assigned to this class if it were to be initialized at the time this method is invoked. If this class has had its assertion status set, the most recent setting will be returned; otherwise, if any package default assertion status pertains to this class, the most recent setting for the most specific pertinent package default assertion status is returned; otherwise, if this class is not a system class (i.e., it has a class loader) its class loader's default assertion status is returned; otherwise, the system class default assertion status is returned.

API Note:

• Few programmers will have any need for this method; it is provided for the benefit of the JDK itself. (It allows a class to determine at the time that it is initialized whether assertions should be enabled.) Note that this method is not guaranteed to return the actual assertion status that was (or will be) associated with the specified class when it was (or will be) initialized. Android-note: AssertionStatuses are unsupported. This method will always return false.

Returns
boolean	the desired assertion status of the specified class.

See also:

• ClassLoader.setClassAssertionStatus(String, boolean)
• ClassLoader.setPackageAssertionStatus(String, boolean)
• ClassLoader.setDefaultAssertionStatus(boolean)

forName

Added in API level 1

public static Class<?> forName (String name, 
                boolean initialize, 
                ClassLoader loader)

Returns the Class object associated with the class or interface with the given string name, using the given class loader. Given the fully qualified name for a class or interface (in the same format returned by getName) this method attempts to locate 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

Returns
Class<?>	class object representing the desired class

Throws
LinkageError	if the linkage fails
ExceptionInInitializerError	if the initialization provoked by this method fails
ClassNotFoundException	if the class cannot be located by the specified class loader

See also:

• forName(String)
• ClassLoader

forName

Added in API level 1

public static Class<?> forName (String className)

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.

Returns
Class<?>	the Class object for the class with the specified name.

Throws
LinkageError	if the linkage fails
ExceptionInInitializerError	if the initialization provoked by this method fails
ClassNotFoundException	if the class cannot be located

getAnnotation

Added in API level 1

public A getAnnotation (Class<A> annotationClass)

Note that any annotation returned by this method is a declaration annotation.

Parameters
annotationClass	Class

Returns
A

Throws
NullPointerException

getAnnotations

Added in API level 1

public Annotation[] getAnnotations ()

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.

Returns
Annotation[]	annotations present on this element

getAnnotationsByType

Added in API level 24

public A[] getAnnotationsByType (Class<A> annotationClass)

Note that any annotations returned by this method are declaration annotations.

Parameters
annotationClass	Class

Returns
A[]

Throws
NullPointerException

getCanonicalName

Added in API level 1

public String getCanonicalName ()

Returns the canonical name of the underlying class as defined by The Java Language Specification. Returns null if the underlying class does not have a canonical name. Classes without canonical names include:

• a local class
• a anonymous class
• an array whose component type does not have a canonical name

Returns
String	the canonical name of the underlying class if it exists, and null otherwise.

getClassLoader

Added in API level 1

public ClassLoader getClassLoader ()

Returns the class loader for the class. Some implementations may use null to represent the bootstrap class loader. This method will return null in such implementations if this class was loaded by the bootstrap class loader.

If this Class object represents a primitive type or void, null is returned.

Returns
ClassLoader	the class loader that loaded the class or interface represented by this Class object.

See also:

• ClassLoader
• SecurityManager.checkPermission(Permission)
• RuntimePermission

getClasses

Added in API level 1

public Class[]<?> getClasses ()

Returns an array containing Class objects representing all the public classes and interfaces that are members of the class represented by this Class object. This includes public class and interface members inherited from superclasses and public class and interface members declared by the class. This method returns an array of length 0 if this Class object has no public member classes or interfaces. This method also returns an array of length 0 if this Class object represents a primitive type, an array class, or void.

Returns
Class[]<?>	the array of Class objects representing the public members of this class

getComponentType

Added in API level 1

public Class<?> getComponentType ()

Returns the Class representing the component type of an array. If this class does not represent an array class this method returns null.

Returns
Class<?>	the Class representing the component type of this class if this class is an array

See also:

• Array

getConstructor

Added in API level 1

public Constructor<T> getConstructor (Class...<?> parameterTypes)

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

Returns
Constructor<T>	the Constructor object of the public constructor that matches the specified parameterTypes

Throws
NoSuchMethodException	if a matching method is not found.
SecurityException	If a security manager, s, is present and the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class.

getConstructors

Added in API level 1

public Constructor[]<?> getConstructors ()

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.

API Note:

• While this method returns an array of Constructor<T> objects (that is an array of constructors from this class), the return type of this method is Constructor<?>[] and not Constructor<T>[] as might be expected. This less informative return type is necessary since after being returned from this method, the array could be modified to hold Constructor objects for different classes, which would violate the type guarantees of Constructor<T>[].

Returns
Constructor[]<?>	the array of Constructor objects representing the public constructors of this class

Throws
SecurityException	If a security manager, s, is present and the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class.

getDeclaredAnnotation

Added in API level 24

public A getDeclaredAnnotation (Class<A> annotationClass)

Note that any annotation returned by this method is a declaration annotation.

Parameters
annotationClass	Class

Returns
A

Throws
NullPointerException

getDeclaredAnnotations

Added in API level 1

public Annotation[] getDeclaredAnnotations ()

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.

Returns
Annotation[]	annotations directly present on this element

getDeclaredAnnotationsByType

Added in API level 24

public A[] getDeclaredAnnotationsByType (Class<A> annotationClass)

Note that any annotations returned by this method are declaration annotations.

Parameters
annotationClass	Class

Returns
A[]

Throws
NullPointerException

getDeclaredClasses

Added in API level 1

public 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. This includes public, protected, default (package) access, and private classes and interfaces declared by the class, but excludes inherited classes and interfaces. This method returns an array of length 0 if the class declares no classes or interfaces as members, or if this Class object represents a primitive type, an array class, or void.

Returns
Class[]<?>	the array of Class objects representing all the declared members of this class

Throws

SecurityException

If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared classes within this class the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredConstructor

Added in API level 1

public Constructor<T> getDeclaredConstructor (Class...<?> parameterTypes)

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

Returns
Constructor<T>	The Constructor object for the constructor with the specified parameter list

Throws
NoSuchMethodException	if a matching method is not found.
SecurityException	If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared constructor the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredConstructors

Added in API level 1

public Constructor[]<?> getDeclaredConstructors ()

Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object. These are public, protected, default (package) access, and private constructors. The elements in the array returned are not sorted and are not in any particular order. If the class has a default constructor, it is included in the returned array. This method returns an array of length 0 if this Class object represents an interface, a primitive type, an array class, or void.

See The Java Language Specification, section {@jls 8.2}.

Returns
Constructor[]<?>	the array of Constructor objects representing all the declared constructors of this class

Throws

SecurityException

If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared constructors within this class the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredField

Added in API level 1

public Field getDeclaredField (String name)

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

Returns
Field	the Field object for the specified field in this class

Throws
NoSuchFieldException	if a field with the specified name is not found.
NullPointerException	if name is null
SecurityException	If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared field the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredFields

Added in API level 1

public Field[] getDeclaredFields ()

Returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object. This includes public, protected, default (package) access, and private fields, but excludes inherited fields.

If this Class object represents a class or interface with no declared fields, then this method returns an array of length 0.

If this Class object represents an array type, a primitive type, or void, then this method returns an array of length 0.

The elements in the returned array are not sorted and are not in any particular order.

Returns
Field[]	the array of Field objects representing all the declared fields of this class

Throws

SecurityException

If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared fields within this class the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredMethod

Added in API level 1

public Method getDeclaredMethod (String name, 
                Class...<?> parameterTypes)

Returns a Method object that reflects the specified declared method of the class or interface represented by this Class object. 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

Returns
Method	the Method object for the method of this class matching the specified name and parameters

Throws
NoSuchMethodException	if a matching method is not found.
NullPointerException	if name is null
SecurityException	If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared method the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getDeclaredMethods

Added in API level 1

public 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. The declared methods may include methods not in the source of the class or interface, including bridge methods and other synthetic methods added by compilers.

If this Class object represents a class or interface that has multiple declared methods with the same name and parameter types, but different return types, then the returned array has a Method object for each such method.

If this Class object represents a class or interface that has a class initialization method <clinit>, then the returned array does not have a corresponding Method object.

If this Class object represents a class or interface with no declared methods, then the returned array has length 0.

If this Class object represents an array type, a primitive type, or void, then the returned array has length 0.

The elements in the returned array are not sorted and are not in any particular order.

Returns
Method[]	the array of Method objects representing all the declared methods of this class

Throws

SecurityException

If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared methods within this class the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

See also:

• Java programming language and JVM modeling in core reflection

getDeclaringClass

Added in API level 1

public 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. This method returns null if this class or interface is not a member of any other class. If this Class object represents an array class, a primitive type, or void,then this method returns null.

Returns
Class<?>	the declaring class for this class

getEnclosingClass

Added in API level 1

public Class<?> getEnclosingClass ()

Returns the immediately enclosing class of the underlying class. If the underlying class is a top level class this method returns null.

Returns
Class<?>	the immediately enclosing class of the underlying class

getEnclosingConstructor

Added in API level 1

public Constructor<?> getEnclosingConstructor ()

If this Class object represents a local or anonymous class within a constructor, returns a Constructor object representing the immediately enclosing constructor of the underlying class. Returns null otherwise. In particular, this method returns null if the underlying class is a local or anonymous class immediately enclosed by a class or interface declaration, instance initializer or static initializer.

Returns
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

public Method getEnclosingMethod ()

If this Class object represents a local or anonymous class within a method, returns a Method object representing the immediately enclosing method of the underlying class. Returns null otherwise. In particular, this method returns null if the underlying class is a local or anonymous class immediately enclosed by a class or interface declaration, instance initializer or static initializer.

Returns
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

public T[] getEnumConstants ()

Returns the elements of this enum class or null if this Class object does not represent an enum class.

Returns
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

public Field getField (String name)

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

Returns
Field	the Field object of this class specified by name

Throws
NoSuchFieldException	if a field with the specified name is not found.
NullPointerException	if name is null
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

public Field[] getFields ()

Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object.

If this Class object represents a class or interface with no accessible public fields, then this method returns an array of length 0.

If this Class object represents a class, then this method returns the public fields of the class and of all its superclasses and superinterfaces.

If this Class object represents an interface, then this method returns the fields of the interface and of all its superinterfaces.

If this Class object represents an array type, a primitive type, or void, then this method returns an array of length 0.

The elements in the returned array are not sorted and are not in any particular order.

Returns
Field[]	the array of Field objects representing the public fields

Throws
SecurityException	If a security manager, s, is present and the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class.

getGenericInterfaces

Added in API level 1

public Type[] getGenericInterfaces ()

Returns the Types representing the interfaces directly implemented by the class or interface represented by this Class object.

If a superinterface is a parameterized type, the Type object returned for it must accurately reflect the actual type arguments used in the source code. The parameterized type representing each superinterface is created if it had not been created before. See the declaration of ParameterizedType for the semantics of the creation process for parameterized types.

If this Class object represents a class, the return value is an array containing objects representing all interfaces directly implemented by the class. The order of the interface objects in the array corresponds to the order of the interface names in the implements clause of the declaration of the class represented by this Class object.

If this Class object represents an interface, the array contains objects representing all interfaces directly extended by the interface. The order of the interface objects in the array corresponds to the order of the interface names in the extends clause of the declaration of the interface represented by this Class object.

If this Class object represents a class or interface that implements no interfaces, the method returns an array of length 0.

If this Class object represents a primitive type or void, the method returns an array of length 0.

If this Class object represents an array type, the interfaces Cloneable and java.io.Serializable are returned in that order.

Returns
Type[]	an array of interfaces directly implemented by this class

Throws
GenericSignatureFormatError	if the generic class signature does not conform to the format specified in section {@jvms 4.7.9} of The Java Virtual Machine Specification
TypeNotPresentException	if any of the generic superinterfaces refers to a non-existent type declaration
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

public Type getGenericSuperclass ()

Returns the Type representing the direct superclass of the entity (class, interface, primitive type or void) represented by this Class object.

If the superclass is a parameterized type, the Type object returned must accurately reflect the actual type arguments used in the source code. The parameterized type representing the superclass is created if it had not been created before. See the declaration of ParameterizedType for the semantics of the creation process for parameterized types. If this Class object represents either the Object class, an interface, a primitive type, or void, then null is returned. If this Class object represents an array class then the Class object representing the Object class is returned.

Returns
Type	the direct superclass of the class represented by this Class object

Throws
GenericSignatureFormatError	if the generic class signature does not conform to the format specified in section {@jvms 4.7.9} of The Java Virtual Machine Specification
TypeNotPresentException	if the generic superclass refers to a non-existent type declaration
MalformedParameterizedTypeException	if the generic superclass refers to a parameterized type that cannot be instantiated for any reason

getInterfaces

Added in API level 1

public Class[]<?> getInterfaces ()

Returns the interfaces directly implemented by the class or interface represented by this Class object.

If this Class object represents a class, the return value is an array containing objects representing all interfaces directly implemented by the class. The order of the interface objects in the array corresponds to the order of the interface names in the implements clause of the declaration of the class represented by this Class object. For example, given the declaration:

class Shimmer implements FloorWax, DessertTopping { ... }

suppose the value of s is an instance of Shimmer; the value of the expression:

s.getClass().getInterfaces()[0]

is the Class object that represents interface FloorWax; and the value of:

s.getClass().getInterfaces()[1]

is the Class object that represents interface DessertTopping.

If this Class object represents an interface, the array contains objects representing all interfaces directly extended by the interface. The order of the interface objects in the array corresponds to the order of the interface names in the extends clause of the declaration of the interface represented by this Class object.

If this Class object represents a class or interface that implements no interfaces, the method returns an array of length 0.

If this Class object represents a primitive type or void, the method returns an array of length 0.

If this Class object represents an array type, the interfaces Cloneable and java.io.Serializable are returned in that order.

Returns
Class[]<?>	an array of interfaces directly implemented by this class

getMethod

Added in API level 1

public Method getMethod (String name, 
                Class...<?> parameterTypes)

Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object. 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(Class)(S.class).

API Note:

• There may be more than one method with matching name and parameter types in a class because while the Java language forbids a class to declare multiple methods with the same signature but different return types, the Java virtual machine does not. This increased flexibility in the virtual machine can be used to implement various language features. For example, covariant returns can be implemented with bridge methods; the bridge method and the overriding method would have the same signature but different return types. This method would return the overriding method as it would have a more specific return type.

Parameters
name	String: the name of the method
parameterTypes	Class: the list of parameters

Returns
Method	the Method object that matches the specified name and parameterTypes

Throws
NoSuchMethodException	if a matching method is not found or if the name is "<init>"or "<clinit>".
NullPointerException	if name is null
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

public 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.

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.

API Note:

• There may be more than one method with a particular name and parameter types in a class because while the Java language forbids a class to declare multiple methods with the same signature but different return types, the Java virtual machine does not. This increased flexibility in the virtual machine can be used to implement various language features. For example, covariant returns can be implemented with bridge methods; the bridge method and the overriding method would have the same signature but different return types.

Returns
Method[]	the array of Method objects representing the public methods of this class

Throws
SecurityException	If a security manager, s, is present and the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class.

getModifiers

Added in API level 1

public int getModifiers ()

Returns the Java language modifiers for this class or interface, encoded in an integer. The modifiers consist of the Java Virtual Machine's constants for public, protected, private, final, static, abstract and interface; they should be decoded using the methods of class Modifier.

If the underlying class is an array class, then its public, private and protected modifiers are the same as those of its component type. If this Class object represents a primitive type or void, its public modifier is always true, and its protected and private modifiers are always false. If this Class object represents an array class, a primitive type or void, then its final modifier is always true and its interface modifier is always false. The values of its other modifiers are not determined by this specification.

The modifier encodings are defined in section {@jvms 4.1} of The Java Virtual Machine Specification.

Returns
int	the int representing the modifiers for this class

See also:

• Modifier
• Java programming language and JVM modeling in core reflection

getName

Added in API level 1

public String getName ()

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"
 

Returns
String	the name of the class, interface, or other entity represented by this Class object.

getNestHost

Added in API level 34

public Class<?> getNestHost ()

Returns the nest host of the nest to which the class or interface represented by this Class object belongs. Every class and interface belongs to exactly one nest. If the nest host of this class or interface has previously been determined, then this method returns the nest host. If the nest host of this class or interface has not previously been determined, then this method determines the nest host using the algorithm of JVMS 5.4.4, and returns it. Often, a class or interface belongs to a nest consisting only of itself, in which case this method returns this to indicate that the class or interface is the nest host.

If this Class object represents a primitive type, an array type, or void, then this method returns this, indicating that the represented entity belongs to the nest consisting only of itself, and is the nest host.

Returns
Class<?>	the nest host of this class or interface

getNestMembers

Added in API level 34

public Class[]<?> getNestMembers ()

Returns an array containing Class objects representing all the classes and interfaces that are members of the nest to which the class or interface represented by this Class object belongs. First, this method obtains the nest host, H, of the nest to which the class or interface represented by this Class object belongs. The zeroth element of the returned array is H. Then, for each class or interface C which is recorded by H as being a member of its nest, this method attempts to obtain the Class object for C (using the defining class loader of the current Class object), and then obtains the nest host of the nest to which C belongs. The classes and interfaces which are recorded by H as being members of its nest, and for which H can be determined as their nest host, are indicated by subsequent elements of the returned array. The order of such elements is unspecified. Duplicates are permitted.

If this Class object represents a primitive type, an array type, or void, then this method returns a single-element array containing this.

API Note:

• The returned array includes only the nest members recorded in the NestMembers attribute.

Returns
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

public Package getPackage ()

Gets the package of this class.

If this class represents an array type, a primitive type or void, this method returns null.

Returns
Package	the package of this class.

getPackageName

Added in API level 31

public String getPackageName ()

Returns the fully qualified package name.

If this class is a top level class, then this method returns the fully qualified name of the package that the class is a member of, or the empty string if the class is in an unnamed package.

If this class is a member class, then this method is equivalent to invoking getPackageName() on the enclosing class.

If this class is a local class or an anonymous class, then this method is equivalent to invoking getPackageName() on the declaring class of the enclosing method or enclosing constructor.

If this class represents an array type then this method returns the package name of the element type. If this class represents a primitive type or void then the package name "java.lang" is returned.

Returns
String	the fully qualified package name

getPermittedSubclasses

Added in API level 34

public Class[]<?> getPermittedSubclasses ()

Returns an array containing Class objects representing the direct subinterfaces or subclasses permitted to extend or implement this class or interface if it is sealed. The order of such elements is unspecified. The array is empty if this sealed class or interface has no permitted subclass. If this Class object represents a primitive type, void, an array type, or a class or interface that is not sealed, that is isSealed() returns false, then this method returns null. Conversely, if isSealed() returns true, then this method returns a non-null value. For each class or interface C which is recorded as a permitted direct subinterface or subclass of this class or interface, this method attempts to obtain the Class object for C (using the defining class loader of the current Class object). The Class objects which can be obtained and which are direct subinterfaces or subclasses of this class or interface, are indicated by elements of the returned array. If a Class object cannot be obtained, it is silently ignored, and not included in the result array.

Returns
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

public ProtectionDomain getProtectionDomain ()

Returns the ProtectionDomain of this class. If there is a security manager installed, this method first calls the security manager's checkPermission method with a RuntimePermission("getProtectionDomain") permission to ensure it's ok to get the ProtectionDomain.

Returns
ProtectionDomain	the ProtectionDomain of this class

Throws
SecurityException	if a security manager exists and its checkPermission method doesn't allow getting the ProtectionDomain.

See also:

• ProtectionDomain
• SecurityManager.checkPermission(Permission)
• RuntimePermission

getRecordComponents

Added in API level 34

public 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.

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.

API Note:

• The following method can be used to find the record canonical constructor:

  static <T extends Record> Constructor<T> getCanonicalConstructor(Class<T> cls)
       throws NoSuchMethodException {
     Class<?>[] paramTypes =
       Arrays.stream(cls.getRecordComponents())
             .map(RecordComponent::getType)
             .toArray(Class<?>[]::new);
     return cls.getDeclaredConstructor(paramTypes);
   }

Returns
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

Throws

SecurityException

If a security manager, s, is present and any of the following conditions is met: the caller's class loader is not the same as the class loader of this class and invocation of s.checkPermission method with RuntimePermission("accessDeclaredMembers") denies access to the declared methods within this class the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of s.checkPackageAccess() denies access to the package of this class

getResource

Added in API level 1

public URL getResource (String name)

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

Returns
URL	A URL object; null if no resource with this name is found.

Throws
NullPointerException	If name is null

getResourceAsStream

Added in API level 1

public InputStream getResourceAsStream (String name)

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

Returns
InputStream	A InputStream object; null if no resource with this name is found.

Throws
NullPointerException	If name is null

getSigners

Added in API level 1

public Object[] getSigners ()

Gets the signers of this class.

Returns
Object[]	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

public String getSimpleName ()

Returns the simple name of the underlying class as given in the source code. An empty string is returned if the underlying class is anonymous. A synthetic class, one not present in source code, can have a non-empty name including special characters, such as "$".

The simple name of an array class is the simple name of the component type with "[]" appended. In particular the simple name of an array class whose component type is anonymous is "[]".

Returns
String	the simple name of the underlying class

getSuperclass

Added in API level 1

public Class<? super T> getSuperclass ()

Returns the Class representing the direct superclass of the entity (class, interface, primitive type or void) represented by this Class. If this Class represents either the Object class, an interface, a primitive type, or void, then null is returned. If this Class object represents an array class then the Class object representing the Object class is returned.

Returns
Class<? super T>	the direct superclass of the class represented by this Class object

getTypeName

Added in API level 26

public String getTypeName ()

Return an informative string for the name of this class or interface.

Returns
String	an informative string for the name of this class or interface

getTypeParameters

Added in API level 1

public 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. Returns an array of length 0 if the underlying generic declaration declares no type variables.

Returns
TypeVariable[]<Class<T>>	an array of TypeVariable objects that represent the type variables declared by this generic declaration

Throws
GenericSignatureFormatError	if the generic signature of this generic declaration does not conform to the format specified in section {@jvms 4.7.9} of The Java Virtual Machine Specification

isAnnotation

Added in API level 1

public boolean isAnnotation ()

Returns true if this Class object represents an annotation interface. Note that if this method returns true, isInterface() would also return true, as all annotation interfaces are also interfaces.

Returns
boolean	true if this Class object represents an annotation interface; false otherwise

isAnnotationPresent

Added in API level 1

public boolean isAnnotationPresent (Class<? extends Annotation> annotationClass)

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: the Class object corresponding to the annotation type

Returns
boolean	true if an annotation for the specified annotation type is present on this element, else false

Throws
NullPointerException

isAnonymousClass

Added in API level 1

public boolean isAnonymousClass ()

Returns true if and only if the underlying class is an anonymous class.

Returns
boolean	true if and only if this class is an anonymous class.

isArray

Added in API level 1

public boolean isArray ()

Determines if this Class object represents an array class.

Returns
boolean	true if this Class object represents an array class; false otherwise.

isAssignableFrom

Added in API level 1

public boolean isAssignableFrom (Class<?> cls)

Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter. 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

Returns
boolean	the boolean value indicating whether objects of the type cls can be assigned to objects of this class

Throws
NullPointerException	if the specified Class parameter is null.

isEnum

Added in API level 1

public boolean isEnum ()

Returns true if and only if this class was declared as an enum in the source code. Note that Enum is not itself an enum class. Also note that if an enum constant is declared with a class body, the class of that enum constant object is an anonymous class and not the class of the declaring enum class. The Enum.getDeclaringClass method of an enum constant can be used to get the class of the enum class declaring the constant.

Returns
boolean	true if and only if this class was declared as an enum in the source code

isInstance

Added in API level 1

public boolean isInstance (Object obj)

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	Object: the object to check

Returns
boolean	true if obj is an instance of this class

isInterface

Added in API level 1

public boolean isInterface ()

Determines if this Class object represents an interface type.

Returns
boolean	true if this Class object represents an interface; false otherwise.

isLocalClass

Added in API level 1

public boolean isLocalClass ()

Returns true if and only if the underlying class is a local class.

Returns
boolean	true if and only if this class is a local class.

isMemberClass

Added in API level 1

public boolean isMemberClass ()

Returns true if and only if the underlying class is a member class.

Returns
boolean	true if and only if this class is a member class.

isNestmateOf

Added in API level 34

public boolean isNestmateOf (Class<?> c)

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

Returns
boolean	true if this class and c are members of the same nest; and false otherwise.

isPrimitive

Added in API level 1

public boolean isPrimitive ()

Determines if the specified Class object represents a primitive type.

There are nine predefined Class objects to represent the eight primitive types and void. These are created by the Java Virtual Machine, and have the same names as the primitive types that they represent, namely boolean, byte, char, short, int, long, float, and double.

These objects may only be accessed via the following public static final variables, and are the only Class objects for which this method returns true.

Returns
boolean	true if and only if this class represents a primitive type

See also:

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

isRecord

Added in API level 34

public boolean isRecord ()

Returns true if and only if this class is a record class.

The direct superclass of a record class is java.lang.Record. A record class is final. A record class has (possibly zero) record components; getRecordComponents() returns a non-null but possibly empty value for a record.

Note that class Record is not a record class and thus invoking this method on class Record returns false.

Returns
boolean	true if and only if this class is a record class, otherwise false

isSealed

Added in API level 34

public boolean isSealed ()

Returns true if and only if this Class object represents a sealed class or interface. If this Class object represents a primitive type, void, or an array type, this method returns false. A sealed class or interface has (possibly zero) permitted subclasses; getPermittedSubclasses() returns a non-null but possibly empty value for a sealed class or interface.

Returns
boolean	true if and only if this Class object represents a sealed class or interface.

isSynthetic

Added in API level 1

public boolean isSynthetic ()

Returns
boolean	true if and only if this class has the synthetic modifier bit set

See also:

• Java programming language and JVM modeling in core reflection

newInstance

Added in API level 1
Deprecated in API level 34

public T newInstance ()

This method was deprecated in API level 34.
This method propagates any exception thrown by the nullary constructor, including a checked exception. Use of this method effectively bypasses the compile-time exception checking that would otherwise be performed by the compiler. The Constructor.newInstance method avoids this problem by wrapping any exception thrown by the constructor in a (checked) InvocationTargetException.

The call

clazz.newInstance()
 

can be replaced by

clazz.getDeclaredConstructor().newInstance()
 

The latter sequence of calls is inferred to be able to throw the additional exception types InvocationTargetException and NoSuchMethodException. Both of these exception types are subclasses of ReflectiveOperationException.

Creates a new instance of the class represented by this Class object. The class is instantiated as if by a new expression with an empty argument list. The class is initialized if it has not already been initialized.

Returns
T	a newly allocated instance of the class represented by this object.

Throws
IllegalAccessException	if the class or its nullary constructor is not accessible.
InstantiationException	if this Class represents an abstract class, an interface, an array class, a primitive type, or void; or if the class has no nullary constructor; or if the instantiation fails for some other reason.
ExceptionInInitializerError	if the initialization provoked by this method fails.

toGenericString

Added in API level 26

public String toGenericString ()

Returns a string describing this Class, including information about modifiers and type parameters. The string is formatted as a list of type modifiers, if any, followed by the kind of type (empty string for primitive types and class, enum, interface, @interface, or record as appropriate), followed by the type's name, followed by an angle-bracketed comma-separated list of the type's type parameters, if any, including informative bounds on the type parameters, if any. A space is used to separate modifiers from one another and to separate any modifiers from the kind of type. The modifiers occur in canonical order. If there are no type parameters, the type parameter list is elided. For an array type, the string starts with the type name, followed by an angle-bracketed comma-separated list of the type's type parameters, if any, followed by a sequence of [] characters, one set of brackets per dimension of the array.

Note that since information about the runtime representation of a type is being generated, modifiers not present on the originating source code or illegal on the originating source code may be present.

Returns
String	a string describing this Class, including information about modifiers and type parameters

toString

Added in API level 1

public String toString ()

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.

Returns
String	a string representation of this Class object.