Nested Class Summary

Method Summary

Method Details

• toString

  public String toString()

  Converts the object to a string. The string representation is thestring "class" or "interface", followed by a space, and then by thename of the class in the format returned bygetName.If thisClass object represents a primitive type,this method returns the name of the primitive type. IfthisClass object represents void this method returns"void". If thisClass object represents an array type,this method returns "class " followed bygetName.

  Overrides:

  toString in class Object

  Returns:

  a string representation of thisClass object.

• toGenericString

  public String toGenericString()

  Returns a string describing thisClass, includinginformation about modifiers,sealed/non-sealed status, 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 typesandclass,enum,interface,@interface, orrecord as appropriate), followedby the type's name, followed by an angle-bracketedcomma-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 toseparate any modifiers from the kind of type. The modifiersoccur in canonical order. If there are no type parameters, thetype parameter list is elided.For an array type, the string starts with the type name,followed by an angle-bracketed comma-separated list of thetype's type parameters, if any, followed by a sequence of[] characters, one set of brackets per dimension ofthe array.

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

  Returns:

  a string describing thisClass, includinginformation about modifiers and type parameters

  Since:

  1.8

• forName

  public static Class<?> forName(String className) throwsClassNotFoundException

  Returns theClass object associated with the class orinterface with the given string name. Invoking this method isequivalent to:

  Copy

  Class.forName(className, true, currentLoader)

  wherecurrentLoader denotes the defining class loader ofthe current class.

  For example, the following code fragment returns theruntimeClass object for the class namedjava.lang.Thread:

  Copy

  Class<?> t = Class.forName("java.lang.Thread");

  A call toforName("X") causes the class namedX to be initialized.

  In cases where this method is called from a context where there is nocaller frame on the stack (e.g. when called directly from a JNIattached thread), the system class loader is used.

  Parameters:

  className - thebinary name of the class or the string representing an array type

  Returns:

  theClass 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

  SeeJava Language Specification:

  12.2 Loading of Classes and Interfaces
  12.3 Linking of Classes and Interfaces
  12.4 Initialization of Classes and Interfaces
  

• forName

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

  Returns theClass object associated with the class orinterface with the given string name, using the given class loader.Given thebinary name for a class or interface,this method attempts to locate and load the class or interface. The specifiedclass loader is used to load the class or interface. If the parameterloader isnull, the class is loaded through the bootstrapclass loader. The class is initialized only if theinitialize parameter istrue and if it hasnot been initialized earlier.

  This method cannot be used to obtain any of theClass objectsrepresenting primitive types or void, hidden classes or interfaces,or array classes whose element type is a hidden class or interface.Ifname denotes a primitive type or void, for exampleI,an attempt will be made to locate a user-defined class in the unnamed packagewhose name isI instead.To obtain aClass object for a named primitive typesuch asint orlong useforPrimitiveName(String).

  To obtain theClass object associated with an array class,the name consists of one or more'[' representing the depthof the array nesting, followed by the element type as encoded inthe table specified inClass.getName().

  Examples:

  Copy

  Class<?> threadClass = Class.forName("java.lang.Thread", false, currentLoader);Class<?> stringArrayClass = Class.forName("[Ljava.lang.String;", false, currentLoader);Class<?> intArrayClass = Class.forName("[[[I", false, currentLoader);   // Class of int[][][]Class<?> nestedClass = Class.forName("java.lang.Character$UnicodeBlock", false, currentLoader);Class<?> fooClass = Class.forName("Foo", true, currentLoader);

  A call togetName() on theClass object returnedfromforName(N) returnsN.

  A call toforName("[LN;") causes the element typenamedN to be loaded but not initialized regardless of the valueof theinitialize parameter.

  API Note:

  This method throws errors related to loading, linking or initializingas specified in Sections12.2,12.3, and12.4 ofThe Java Language Specification.In addition, this method does not check whether the requested classis accessible to its caller.

  Parameters:

  name - thebinary name of the class or the string representing an array class

  initialize - iftrue the class will be initialized (which implies linking). See Section12.4 ofThe Java Language Specification.

  loader - class loader from which the class must be loaded

  Returns:

  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

  SeeJava Language Specification:

  12.2 Loading of Classes and Interfaces
  12.3 Linking of Classes and Interfaces
  12.4 Initialization of Classes and Interfaces
  13.1 The Form of a Binary
  

  Since:

  1.2

  See Also:

  • forName(String)
  • ClassLoader

• forName

  public static Class<?> forName(Module module,String name)

  Returns theClass with the givenbinary name in the given module.

  This method attempts to locate and load the class or interface.It does not link the class, and does not run the class initializer.If the class is not found, this method returnsnull.

  If the class loader of the given module defines other modules andthe given name is a class defined in a different module, this methodreturnsnull after the class is loaded.

  This method does not check whether the requested class isaccessible to its caller.

  API Note:

  This method does not support loading of array types, unlikeforName(String, boolean, ClassLoader). The class name must bea binary name. This method returnsnull on failure rather thanthrowing aClassNotFoundException, as is done bytheforName(String, boolean, ClassLoader) method.

  Parameters:

  module - A module

  name - Thebinary name of the class

  Returns:

  Class object of the given name defined in the given module;null if not found.

  Throws:

  NullPointerException - if the given module or name isnull

  LinkageError - if the linkage fails

  SeeJava Language Specification:

  12.2 Loading of Classes and Interfaces
  12.3 Linking of Classes and Interfaces
  

  Since:

  9

• forPrimitiveName

  public static Class<?> forPrimitiveName(String primitiveName)

  Returns theClass object associated with theprimitive type of the given name.If the argument is not the name of a primitive type,null is returned.

  Parameters:

  primitiveName - the name of the primitive type to find

  Returns:

  theClass object associated with theprimitive type of the given name

  Throws:

  NullPointerException - if the argument isnull

  SeeJava Language Specification:

  4.2 Primitive Types and Values
  15.8.2 Class Literals
  

  Since:

  22

• newInstance

  @Deprecated(since="9")public T newInstance() throwsInstantiationException,IllegalAccessException

  Deprecated.

  This method propagates any exception thrown by thenullary constructor, including a checked exception. Use ofthis method effectively bypasses the compile-time exceptionchecking that would otherwise be performed by the compiler.TheConstructor.newInstance method avoids this problem by wrappingany exception thrown by the constructor in a (checked)InvocationTargetException.

  The call

  Copy

  clazz.newInstance()

  can be replaced by

  Copy

  clazz.getDeclaredConstructor().newInstance()

  The latter sequence of calls is inferred to be able to throwthe additional exception typesInvocationTargetException andNoSuchMethodException. Both of these exception types aresubclasses ofReflectiveOperationException.

  Creates a new instance of the class represented by thisClassobject. The class is instantiated as if by anewexpression with an empty argument list. The class is initialized if ithas not already been initialized.

  Returns:

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

  Throws:

  IllegalAccessException - if the class or its nullary constructor is not accessible.

  InstantiationException - if thisClass 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.

• isInstance

  public boolean isInstance(Object obj)

  Determines if the specifiedObject is assignment-compatiblewith the object represented by thisClass. This method isthe dynamic equivalent of the Java languageinstanceofoperator. The method returnstrue if the specifiedObject argument is non-null and can be cast to thereference type represented by thisClass object withoutraising aClassCastException. It returnsfalseotherwise.

  Specifically, if thisClass object represents adeclared class, this method returnstrue if the specifiedObject argument is an instance of the represented class (orof any of its subclasses); it returnsfalse otherwise. IfthisClass object represents an array class, this methodreturnstrue if the specifiedObject argumentcan be converted to an object of the array class by an identityconversion or by a widening reference conversion; it returnsfalse otherwise. If thisClass objectrepresents an interface, this method returnstrue if theclass or any superclass of the specifiedObject argumentimplements this interface; it returnsfalse otherwise. IfthisClass object represents a primitive type, this methodreturnsfalse.

  Parameters:

  obj - the object to check

  Returns:

  true ifobj is an instance of this class

  Since:

  1.1

• isAssignableFrom

  public boolean isAssignableFrom(Class<?> cls)

  Determines if the class or interface represented by thisClass object is either the same as, or is a superclass orsuperinterface of, the class or interface represented by the specifiedClass parameter. It returnstrue if so;otherwise it returnsfalse. If thisClassobject represents a primitive type, this method returnstrue if the specifiedClass parameter isexactly thisClass object; otherwise it returnsfalse.

  Specifically, this method tests whether the type represented by thespecifiedClass parameter can be converted to the typerepresented by thisClass object via an identity conversionor via a widening reference conversion. SeeThe Java LanguageSpecification, sections5.1.1 and5.1.4,for details.

  Parameters:

  cls - theClass object to be checked

  Returns:

  theboolean value indicating whether objects of the typecls can be assigned to objects of this class

  Throws:

  NullPointerException - if the specified Class parameter is null.

  Since:

  1.1

• isInterface

  public boolean isInterface()

  Determines if thisClass object represents aninterface type.

  Returns:

  true if thisClass object represents an interface;false otherwise.

• isArray

  public boolean isArray()

  Determines if thisClass object represents an array class.

  Specified by:

  isArray in interface TypeDescriptor.OfField<T>

  Returns:

  true if thisClass object represents an array class;false otherwise.

  Since:

  1.1

• isPrimitive

  public boolean isPrimitive()

  Determines if thisClass object represents a primitivetype or void.

  There are nine predefinedClass objects torepresent the eight primitive types and void. These arecreated by the Java Virtual Machine, and have the samenames as the primitive types that theyrepresent, namelyboolean,byte,char,short,int,long,float, anddouble.

  No other class objects are considered primitive.

  Specified by:

  isPrimitive in interface TypeDescriptor.OfField<T>

  API Note:

  AClass object represented by a primitive type can beaccessed via theTYPE public static final variablesdefined in the primitive wrapper classes such asInteger.TYPE. In the Java programminglanguage, the objects may be referred to by a class literalexpression such asint.class. TheClass objectfor void can be expressed asvoid.class orVoid.TYPE.

  Returns:

  true if and only if this class represents a primitive type

  SeeJava Language Specification:

  15.8.2 Class Literals
  

  Since:

  1.1

  See Also:

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

• isAnnotation

  public boolean isAnnotation()

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

  Returns:

  true if thisClass object represents an annotation interface;false otherwise

  Since:

  1.5

• isSynthetic

  public boolean isSynthetic()

  Returnstrue if and only if this class has the synthetic modifier bit set.

  Returns:

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

  SeeJava Language Specification:

  13.1 The Form of a Binary
  

  SeeJava Virtual Machine Specification:

  4.1 TheClassFile Structure
  

  Since:

  1.5

  See Also:

  • Java programming language and JVM modeling in core reflection

• getName

  public String getName()

  Returns the name of the entity (class, interface, array class,primitive type, or void) represented by thisClass object.

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

  • If the class or interface is nothidden, then thebinary name of the class or interface is returned.
  • If the class or interface is hidden, then the result is a string of the form:N + '/' + <suffix> whereN is thebinary name indicated by theclass file passed toLookup::defineHiddenClass, and<suffix> is an unqualified name.

  If thisClass object represents an array class, thenthe result is a string consisting of one or more '[' charactersrepresenting the depth of the array nesting, followed by the elementtype as encoded using the following table:

  Element types and encodings

  Element Type	Encoding
  boolean	Z
  byte	B
  char	C
  class or interface withbinary nameN	LN;
  double	D
  float	F
  int	I
  long	J
  short	S

  If thisClass object represents a primitive type orvoid,then the result is a string with the same spelling as the Java languagekeyword which corresponds to the primitive type orvoid.

  Examples:

  String.class.getName()    returns "java.lang.String"Character.UnicodeBlock.class.getName()    returns "java.lang.Character$UnicodeBlock"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"

  API Note:

  Distinct class objects can have the same name but different class loaders.

  Returns:

  the name of the class, interface, or other entity represented by thisClass object.

  SeeJava Language Specification:

  13.1 The Form of a Binary
  

• getClassLoader

  public ClassLoader getClassLoader()

  Returns the class loader for the class. Some implementations may usenull to represent the bootstrap class loader. This method will returnnull in such implementations if this class was loaded by the bootstrapclass loader.

  If thisClass objectrepresents a primitive type or void, null is returned.

  Returns:

  the class loader that loaded the class or interface represented by thisClass object.

  See Also:

  • ClassLoader

• getModule

  public Module getModule()

  Returns the module that this class or interface is a member of.If this class represents an array type then this method returns theModule for the element type. If this class represents aprimitive type or void, then theModule object for thejava.base module is returned.If this class is in an unnamed module then theunnamedModule of the classloader for this class is returned.

  Returns:

  the module that this class or interface is a member of

  Since:

  9

• getTypeParameters

  public TypeVariable<Class<T>>[] getTypeParameters()

  Returns an array ofTypeVariable objects that represent thetype variables declared by the generic declaration represented by thisGenericDeclaration object, in declaration order. Returns anarray of length 0 if the underlying generic declaration declares no typevariables.

  Specified by:

  getTypeParameters in interface GenericDeclaration

  Returns:

  an array ofTypeVariable 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 section4.7.9 ofThe Java Virtual Machine Specification

  Since:

  1.5

• getSuperclass

  public Class<? superT> getSuperclass()

  Returns theClass representing the direct superclass of theentity (class, interface, primitive type or void) represented bythisClass. If thisClass represents either theObject class, an interface, a primitive type, or void, thennull is returned. If thisClass object represents an array classthen theClass object representing theObject class isreturned.

  Returns:

  the direct superclass of the class represented by thisClass object

• getGenericSuperclass

  public Type getGenericSuperclass()

  Returns theType representing the direct superclass ofthe entity (class, interface, primitive type or void) represented bythisClass object.

  If the superclass is a parameterized type, theTypeobject returned must accurately reflect the actual typearguments used in the source code. The parameterized typerepresenting the superclass is created if it had not beencreated before. See the declaration ofParameterizedType for thesemantics of the creation process for parameterized types. IfthisClass object represents either theObjectclass, an interface, a primitive type, or void, then null isreturned. If thisClass object represents an array classthen theClass object representing theObject class isreturned.

  Returns:

  the direct superclass of the class represented by thisClass object

  Throws:

  GenericSignatureFormatError - if the generic class signature does not conform to the format specified in section4.7.9 ofThe 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

  Since:

  1.5

• getPackage

  public Package getPackage()

  Gets the package of this class.

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

  Returns:

  the package of this class.

• getPackageName

  public String getPackageName()

  Returns the fully qualified package name.

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

  If this class is a member class, then this method is equivalent toinvokinggetPackageName() on theenclosing class.

  If this class is alocal class or ananonymous class, then this method is equivalent toinvokinggetPackageName() on thedeclaring class of theenclosing method orenclosing constructor.

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

  Returns:

  the fully qualified package name

  SeeJava Language Specification:

  6.7 Fully Qualified Names and Canonical Names
  

  Since:

  9

• getInterfaces

  public Class<?>[] getInterfaces()

  Returns the interfaces directly implemented by the class or interfacerepresented by thisClass object.

  If thisClass object represents a class, the return value is an arraycontaining objects representing all interfaces directly implemented bythe class. The order of the interface objects in the array correspondsto the order of the interface names in theimplements clause ofthe declaration of the class represented by thisClass object. For example,given the declaration:

  class Shimmer implements FloorWax, DessertTopping { ... }

  suppose the value ofs is an instance ofShimmer; the value of the expression:

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

  is theClass object that represents interfaceFloorWax; and the value of:

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

  is theClass object that represents interfaceDessertTopping.

  If thisClass object represents an interface, the array contains objectsrepresenting all interfaces directly extended by the interface. Theorder of the interface objects in the array corresponds to the order ofthe interface names in theextends clause of the declaration ofthe interface represented by thisClass object.

  If thisClass object represents a class or interface that implements nointerfaces, the method returns an array of length 0.

  If thisClass object represents a primitive type or void, the methodreturns an array of length 0.

  If thisClass object represents an array type, theinterfacesCloneable andjava.io.Serializable arereturned in that order.

  Returns:

  an array of interfaces directly implemented by this class

• getGenericInterfaces

  public Type[] getGenericInterfaces()

  Returns theTypes representing the interfacesdirectly implemented by the class or interface represented bythisClass object.

  If a superinterface is a parameterized type, theType object returned for it must accurately reflectthe actual type arguments used in the source code. Theparameterized type representing each superinterface is createdif it had not been created before. See the declaration ofParameterizedTypefor the semantics of the creation process for parameterizedtypes.

  If thisClass object represents a class, the return value is an arraycontaining objects representing all interfaces directly implemented bythe class. The order of the interface objects in the array correspondsto the order of the interface names in theimplements clause ofthe declaration of the class represented by thisClass object.

  If thisClass object represents an interface, the array contains objectsrepresenting all interfaces directly extended by the interface. Theorder of the interface objects in the array corresponds to the order ofthe interface names in theextends clause of the declaration ofthe interface represented by thisClass object.

  If thisClass object represents a class or interface that implements nointerfaces, the method returns an array of length 0.

  If thisClass object represents a primitive type or void, the methodreturns an array of length 0.

  If thisClass object represents an array type, theinterfacesCloneable andjava.io.Serializable arereturned in that order.

  Returns:

  an array of interfaces directly implemented by this class

  Throws:

  GenericSignatureFormatError - if the generic class signature does not conform to the format specified in section4.7.9 ofThe 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

  Since:

  1.5

• getComponentType

  public Class<?> getComponentType()

  Returns theClass representing the component type of anarray. If this class does not represent an array class this methodreturns null.

  Returns:

  theClass representing the component type of thisclass if this class is an array

  Since:

  1.1

  See Also:

  • Array

• getModifiers

  public int getModifiers()

  Returns the Java language modifiers for this class or interface, encodedin an integer. The modifiers consist of the Java Virtual Machine'sconstants forpublic,protected,private,final,static,abstract andinterface; they should be decodedusing the methods of classModifier.

  If the underlying class is an array class:

  • itspublic,private andprotected modifiers are the same as those of its component type
  • itsabstract andfinal modifiers are alwaystrue
  • its interface modifier is alwaysfalse, even when the component type is an interface

  If thisClass object represents a primitive type orvoid, itspublic,abstract, andfinalmodifiers are alwaystrue.ForClass objects representing void, primitive types, andarrays, the values of other modifiers arefalse otherthan as specified above.

  The modifier encodings are defined in section4.1ofThe Java Virtual Machine Specification.

  Returns:

  theint representing the modifiers for this class

  SeeJava Language Specification:

  8.1.1 Class Modifiers
  9.1.1 Interface Modifiers
  

  SeeJava Virtual Machine Specification:

  4.1 TheClassFile Structure
  

  Since:

  1.1

  See Also:

  • Modifier
  • accessFlags()
  • Javaprogramming language and JVM modeling in core reflection

• accessFlags

  public Set<AccessFlag> accessFlags()

  Returns an unmodifiable set of theaccessflags for this class, possibly empty.

  If the underlying class is an array class:

  • itsPUBLIC,PRIVATE andPROTECTED access flags are the same as those of its component type
  • itsABSTRACT andFINAL flags are present
  • itsINTERFACE flag is absent, even when the component type is an interface

  If thisClass object represents a primitive type orvoid, the flags arePUBLIC,ABSTRACT, andFINAL.ForClass objects representing void, primitive types, andarrays, access flags are absent other than as specified above.

  Returns:

  an unmodifiable set of theaccessflags for this class, possibly empty

  SeeJava Virtual Machine Specification:

  4.1 The ClassFile Structure
  4.7.6 The InnerClasses Attribute
  

  Since:

  20

  See Also:

  • getModifiers()

• getSigners

  public Object[] getSigners()

  Gets the signers of this class.

  Returns:

  the signers of this class, or null if there are no signers. In particular, this method returns null if thisClass object represents a primitive type or void.

  Since:

  1.1

• getEnclosingMethod

  public Method getEnclosingMethod()

  If thisClass object represents a local or anonymousclass within a method, returns aMethod object representing theimmediately enclosing method of the underlying class. Returnsnull otherwise.In particular, this method returnsnull if the underlyingclass is a local or anonymous class immediately enclosed by a class orinterface declaration, instance initializer or static initializer.

  Returns:

  the immediately enclosing method of the underlying class, if that class is a local or anonymous class; otherwisenull.

  Since:

  1.5

• getEnclosingConstructor

  public Constructor<?> getEnclosingConstructor()

  If thisClass object represents a local or anonymousclass within a constructor, returns aConstructor object representingthe immediately enclosing constructor of the underlyingclass. Returnsnull otherwise. In particular, thismethod returnsnull if the underlying class is a localor anonymous class immediately enclosed by a class orinterface declaration, instance initializer or static initializer.

  Returns:

  the immediately enclosing constructor of the underlying class, if that class is a local or anonymous class; otherwisenull.

  Since:

  1.5

• getDeclaringClass

  public Class<?> getDeclaringClass()

  If the class or interface represented by thisClass objectis a member of another class, returns theClass objectrepresenting the class in which it was declared. This method returnsnull if this class or interface is not a member of any other class. IfthisClass object represents an array class, a primitivetype, or void, then this method returns null.

  Returns:

  the declaring class for this class

  Since:

  1.1

• getEnclosingClass

  public Class<?> getEnclosingClass()

  Returns the immediately enclosing class of the underlyingclass. If the underlying class is a top level class thismethod returnsnull.

  Returns:

  the immediately enclosing class of the underlying class

  Since:

  1.5

• getSimpleName

  public String getSimpleName()

  Returns the simple name of the underlying class as given in thesource code. An empty string is returned if the underlying class isanonymous.Asynthetic class, one not presentin source code, can have a non-empty name including specialcharacters, such as "$".

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

  Returns:

  the simple name of the underlying class

  Since:

  1.5

• getTypeName

  public String getTypeName()

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

  Specified by:

  getTypeName in interface Type

  Returns:

  an informative string for the name of this class or interface

  Since:

  1.8

• getCanonicalName

  public String getCanonicalName()

  Returns the canonical name of the underlying class asdefined byThe Java Language Specification.Returnsnull if the underlying class does not have a canonicalname. Classes without canonical names include:

  • alocal class
  • aanonymous class
  • ahidden class
  • an array whose component type does not have a canonical name

  The canonical name for a primitive class is the keyword for thecorresponding primitive type (byte,short,char,int, and so on).

  An array type has a canonical name if and only if itscomponent type has a canonical name. When an array type has acanonical name, it is equal to the canonical name of thecomponent type followed by "[]".

  Returns:

  the canonical name of the underlying class if it exists, andnull otherwise.

  SeeJava Language Specification:

  6.7 Fully Qualified Names and Canonical Names
  

  Since:

  1.5

• isAnonymousClass

  public boolean isAnonymousClass()

  Returnstrue if and only if the underlying classis an anonymous class.

  API Note:

  An anonymous class is not ahidden class.

  Returns:

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

  SeeJava Language Specification:

  15.9.5 Anonymous Class Declarations
  

  Since:

  1.5

• isLocalClass

  public boolean isLocalClass()

  Returnstrue if and only if the underlying classis a local class.

  Returns:

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

  SeeJava Language Specification:

  14.3 Local Class and Interface Declarations
  

  Since:

  1.5

• isMemberClass

  public boolean isMemberClass()

  Returnstrue if and only if the underlying classis a member class.

  Returns:

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

  SeeJava Language Specification:

  8.5 Member Class and Interface Declarations
  

  Since:

  1.5

• getClasses

  public Class<?>[] getClasses()

  Returns an array containingClass objects representing allthe public classes and interfaces that are members of the classrepresented by thisClass object. This includes publicclass and interface members inherited from superclasses and public classand interface members declared by the class. This method returns anarray of length 0 if thisClass object has no public memberclasses or interfaces. This method also returns an array of length 0 ifthisClass object represents a primitive type, an arrayclass, or void.

  Returns:

  the array ofClass objects representing the public members of this class

  Since:

  1.1

• getFields

  public Field[] getFields()

  Returns an array containingField objects reflecting allthe accessible public fields of the class or interface represented bythisClass object.

  If thisClass object represents a class or interface withno accessible public fields, then this method returns an array of length0.

  If thisClass object represents a class, then this methodreturns the public fields of the class and of all its superclasses andsuperinterfaces.

  If thisClass object represents an interface, then thismethod returns the fields of the interface and of all itssuperinterfaces.

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

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

  Returns:

  the array ofField objects representing the public fields

  SeeJava Language Specification:

  8.2 Class Members
  8.3 Field Declarations
  

  Since:

  1.1

• getMethods

  public Method[] getMethods()

  Returns an array containingMethod objects reflecting all thepublic methods of the class or interface represented by thisClass object, including those declared by the class or interface andthose inherited from superclasses and superinterfaces.

  If thisClass object represents an array type, then thereturned array has aMethod object for each of the publicmethods inherited by the array type fromObject. It does notcontain aMethod object forclone().

  If thisClass object represents an interface then thereturned array does not contain any implicitly declared methods fromObject. Therefore, if no methods are explicitly declared inthis interface or any of its superinterfaces then the returned arrayhas length 0. (Note that aClass object which represents a classalways has public methods, inherited fromObject.)

  The returned array never contains methods with names"<init>" or"<clinit>".

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

  Generally, the result is computed as with the following 4 step algorithm.Let C be the class or interface represented by thisClass object:

  1. A union of methods is composed of:
     1. C's declared public instance and static methods as returned bygetDeclaredMethods() and filtered to include only public methods.
     2. If C is a class other thanObject, 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 nameand parameter types in a class because while the Java language forbids aclass to declare multiple methods with the same signature but differentreturn types, the Java virtual machine does not. Thisincreased flexibility in the virtual machine can be used toimplement various language features. For example, covariantreturns can be implemented withbridge methods; the bridgemethod and the overriding method would have the samesignature but different return types.

  Returns:

  the array ofMethod objects representing the public methods of this class

  SeeJava Language Specification:

  8.2 Class Members
  8.4 Method Declarations
  

  Since:

  1.1

• getConstructors

  public Constructor<?>[] getConstructors()

  Returns an array containingConstructor objects reflectingall the public constructors of the class represented by thisClass object. An array of length 0 is returned if theclass has no public constructors, or if the class is an array class, orif the class reflects a primitive type or void.

  API Note:

  While this method returns an array ofConstructor<T> objects (that is an array of constructors fromthis class), the return type of this method isConstructor<?>[] andnotConstructor<T>[] asmight be expected. This less informative return type isnecessary since after being returned from this method, thearray could be modified to holdConstructor objects fordifferent classes, which would violate the type guarantees ofConstructor<T>[].

  Returns:

  the array ofConstructor objects representing the public constructors of this class

  Since:

  1.1

  See Also:

  • getDeclaredConstructors()

• getField

  public Field getField(String name) throwsNoSuchFieldException

  Returns aField object that reflects the specified public memberfield of the class or interface represented by thisClassobject. Thename parameter is aString specifying thesimple name of the desired field.

  The field to be reflected is determined by the algorithm thatfollows. Let C be the class or interface represented by thisClass 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 aNoSuchFieldException is thrown.

  If thisClass object represents an array type, then thismethod does not find thelength field of the array type.

  Parameters:

  name - the field name

  Returns:

  theField object of this class specified byname

  Throws:

  NoSuchFieldException - if a field with the specified name is not found.

  NullPointerException - ifname isnull

  SeeJava Language Specification:

  8.2 Class Members
  8.3 Field Declarations
  

  Since:

  1.1

• getMethod

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

  Returns aMethod object that reflects the specified publicmember method of the class or interface represented by thisClass object. Thename parameter is aString specifying the simple name of the desired method. TheparameterTypes parameter is an array ofClassobjects that identify the method's formal parameter types, in declaredorder. IfparameterTypes isnull, it istreated as if it were an empty array.

  If thisClass object represents an array type, then thismethod finds any public method inherited by the array type fromObject except methodclone().

  If thisClass object represents an interface then thismethod does not find any implicitly declared method fromObject. Therefore, if no methods are explicitly declared inthis interface or any of its superinterfaces, then this method does notfind 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 stepalgorithm that follows.Let C be the class or interface represented by thisClass object:

  1. A union of methods is composed of:
     1. C's declared public instance and static methods as returned bygetDeclaredMethods() and filtered to include only public methods that match givenname andparameterTypes
     2. If C is a class other thanObject, 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 andparameter types in a class because while the Java language forbids aclass to declare multiple methods with the same signature but differentreturn types, the Java virtual machine does not. Thisincreased flexibility in the virtual machine can be used toimplement various language features. For example, covariantreturns can be implemented withbridge methods; the bridgemethod and the overriding method would have the samesignature but different return types. This method would return theoverriding method as it would have a more specific return type.

  Parameters:

  name - the name of the method

  parameterTypes - the list of parameters

  Returns:

  theMethod object that matches the specifiedname andparameterTypes

  Throws:

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

  NullPointerException - ifname isnull

  SeeJava Language Specification:

  8.2 Class Members
  8.4 Method Declarations
  

  Since:

  1.1

• getConstructor

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

  Returns aConstructor object that reflects the specifiedpublic constructor of the class represented by thisClassobject. TheparameterTypes parameter is an array ofClass objects that identify the constructor's formalparameter types, in declared order.If thisClass object represents an inner classdeclared in a non-static context, the formal parameter typesinclude the explicit enclosing instance as the first parameter.

  The constructor to reflect is the public constructor of the classrepresented by thisClass object whose formal parametertypes match those specified byparameterTypes.

  Parameters:

  parameterTypes - the parameter array

  Returns:

  theConstructor object of the public constructor that matches the specifiedparameterTypes

  Throws:

  NoSuchMethodException - if a matching constructor is not found, including when thisClass object represents an interface, a primitive type, an array class, or void.

  Since:

  1.1

  See Also:

  • getDeclaredConstructor(Class[])

• getDeclaredClasses

  public Class<?>[] getDeclaredClasses()

  Returns an array ofClass objects reflecting all theclasses and interfaces declared as members of the class represented bythisClass object. This includes public, protected, default(package) access, and private classes and interfaces declared by theclass, but excludes inherited classes and interfaces. This methodreturns an array of length 0 if the class declares no classes orinterfaces as members, or if thisClass object represents aprimitive type, an array class, or void.

  Returns:

  the array ofClass objects representing all the declared members of this class

  SeeJava Language Specification:

  8.5 Member Class and Interface Declarations
  

  Since:

  1.1

• getDeclaredFields

  public Field[] getDeclaredFields()

  Returns an array ofField objects reflecting all the fieldsdeclared by the class or interface represented by thisClass object. This includes public, protected, default(package) access, and private fields, but excludes inherited fields.

  If thisClass object represents a class or interface with nodeclared fields, then this method returns an array of length 0.

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

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

  Returns:

  the array ofField objects representing all the declared fields of this class

  SeeJava Language Specification:

  8.2 Class Members
  8.3 Field Declarations
  

  Since:

  1.1

• getRecordComponents

  public RecordComponent[] getRecordComponents()

  Returns an array ofRecordComponent objects representing all therecord components of this record class, ornull if this class isnot a record class.

  The components are returned in the same order that they are declaredin the record header. The array is empty if this record class has nocomponents. If the class is not a record class, that isisRecord() returnsfalse, then this method returnsnull.Conversely, ifisRecord() returnstrue, then this methodreturns a non-null value.

  API Note:

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

  Copy

  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:

  An array ofRecordComponent objects representing all the record components of this record class, ornull if this class is not a record class

  SeeJava Language Specification:

  8.10 Record Classes
  

  Since:

  16

• getDeclaredMethods

  public Method[] getDeclaredMethods()

  Returns an array containingMethod objects reflecting all thedeclared methods of the class or interface represented by thisClass object, including public, protected, default (package)access, and private methods, but excluding inherited methods.The declared methods may include methodsnot in thesource of the class or interface, includingbridge methods and othersynthetic methods added by compilers.

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

  If thisClass object represents a class or interface thathas a class initialization method"<clinit>",then the returned array doesnot have a correspondingMethod object.

  If thisClass object represents a class or interface with nodeclared methods, then the returned array has length 0.

  If thisClass object represents an array type, a primitivetype, or void, then the returned array has length 0.

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

  Returns:

  the array ofMethod objects representing all the declared methods of this class

  SeeJava Language Specification:

  8.2 Class Members
  8.4 Method Declarations
  

  Since:

  1.1

  See Also:

  • Javaprogramming language and JVM modeling in core reflection

• getDeclaredConstructors

  public Constructor<?>[] getDeclaredConstructors()

  Returns an array ofConstructor objects reflecting all theconstructors implicitly or explicitly declared by the class represented by thisClass object. These are public, protected, default(package) access, and private constructors. The elements in the arrayreturned are not sorted and are not in any particular order. If theclass has a default constructor (JLS8.8.9), it is included in the returned array.If a record class has a canonical constructor (JLS8.10.4.1,8.10.4.2), it is included in the returned array.This method returns an array of length 0 if thisClassobject represents an interface, a primitive type, an array class, orvoid.

  Returns:

  the array ofConstructor objects representing all the declared constructors of this class

  SeeJava Language Specification:

  8.8 Constructor Declarations
  

  Since:

  1.1

  See Also:

  • getConstructors()

• getDeclaredField

  public Field getDeclaredField(String name) throwsNoSuchFieldException

  Returns aField object that reflects the specified declaredfield of the class or interface represented by thisClassobject. Thename parameter is aString that specifiesthe simple name of the desired field.

  If thisClass object represents an array type, then thismethod does not find thelength field of the array type.

  Parameters:

  name - the name of the field

  Returns:

  theField object for the specified field in this class

  Throws:

  NoSuchFieldException - if a field with the specified name is not found.

  NullPointerException - ifname isnull

  SeeJava Language Specification:

  8.2 Class Members
  8.3 Field Declarations
  

  Since:

  1.1

• getDeclaredMethod

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

  Returns aMethod object that reflects the specifieddeclared method of the class or interface represented by thisClass object. Thename parameter is aString that specifies the simple name of the desiredmethod, and theparameterTypes parameter is an array ofClass objects that identify the method's formal parametertypes, in declared order. If more than one method with the sameparameter types is declared in a class, and one of these methods has areturn type that is more specific than any of the others, that method isreturned; otherwise one of the methods is chosen arbitrarily. If thename is"<init>" or"<clinit>" aNoSuchMethodExceptionis raised.

  If thisClass object represents an array type, then thismethod does not find theclone() method.

  Parameters:

  name - the name of the method

  parameterTypes - the parameter array

  Returns:

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

  Throws:

  NoSuchMethodException - if a matching method is not found.

  NullPointerException - ifname isnull

  SeeJava Language Specification:

  8.2 Class Members
  8.4 Method Declarations
  

  Since:

  1.1

• getDeclaredConstructor

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

  Returns aConstructor object that reflects the specifiedconstructor of the class represented by thisClass object. TheparameterTypes parameter isan array ofClass objects that identify the constructor'sformal parameter types, in declared order.If thisClass object represents an inner classdeclared in a non-static context, the formal parameter typesinclude the explicit enclosing instance as the first parameter.

  Parameters:

  parameterTypes - the parameter array

  Returns:

  TheConstructor object for the constructor with the specified parameter list

  Throws:

  NoSuchMethodException - if a matching constructor is not found, including when thisClass object represents an interface, a primitive type, an array class, or void.

  Since:

  1.1

  See Also:

  • getConstructor(Class[])

• getResourceAsStream

  public InputStream getResourceAsStream(String name)

  Finds a resource with a given name.

  If this class is in a namedModule then this methodwill attempt to find the resource in the module. This is done bydelegating to the module's class loaderfindResource(String,String)method, invoking it with the module name and the absolute name of theresource. Resources in named modules are subject to the rules forencapsulation specified in theModulegetResourceAsStream method and so thismethod returnsnull when the resource is anon-".class" resource in a package that is not open to thecaller's module.

  Otherwise, if this class is not in a named module then the rules forsearching resources associated with a given class are implemented by thedefiningclass loader of the class. This methoddelegates to thisClass object's class loader.If thisClass object was loaded by the bootstrap class loader,the method delegates toClassLoader.getSystemResourceAsStream(String).

  Before delegation, an absolute resource name is constructed from thegiven resource name using this algorithm:

  • If thename begins with a'/'('\u002f'), then the absolute name of the resource is theportion of thename following the'/'.
  • Otherwise, the absolute name is of the following form:

    modified_package_name/name

    Where themodified_package_name is the package name of thisobject with'/' substituted for'.'('\u002e').

  Parameters:

  name - name of the desired resource

  Returns:

  AInputStream object;null if no resource with this name is found, or the resource is in a package that is notopen to at least the caller module.

  Throws:

  NullPointerException - Ifname isnull

  Since:

  1.1

  See Also:

  • Module.getResourceAsStream(String)

• getResource

  public URL getResource(String name)

  Finds a resource with a given name.

  If this class is in a namedModule then this methodwill attempt to find the resource in the module. This is done bydelegating to the module's class loaderfindResource(String,String)method, invoking it with the module name and the absolute name of theresource. Resources in named modules are subject to the rules forencapsulation specified in theModulegetResourceAsStream method and so thismethod returnsnull when the resource is anon-".class" resource in a package that is not open to thecaller's module.

  Otherwise, if this class is not in a named module then the rules forsearching resources associated with a given class are implemented by thedefiningclass loader of the class. This methoddelegates to thisClass object's class loader.If thisClass object was loaded by the bootstrap class loader,the method delegates toClassLoader.getSystemResource(String).

  Before delegation, an absolute resource name is constructed from thegiven resource name using this algorithm:

  • If thename begins with a'/'('\u002f'), then the absolute name of the resource is theportion of thename following the'/'.
  • Otherwise, the absolute name is of the following form:

    modified_package_name/name

    Where themodified_package_name is the package name of thisobject with'/' substituted for'.'('\u002e').

  Parameters:

  name - name of the desired resource

  Returns:

  AURL object;null if no resource with this name is found, the resource cannot be located by a URL, or the resource is in a package that is notopen to at least the caller module.

  Throws:

  NullPointerException - Ifname isnull

  Since:

  1.1

• getProtectionDomain

  public ProtectionDomain getProtectionDomain()

  Returns theProtectionDomain of this class.

  Returns:

  the ProtectionDomain of this class

  Since:

  1.2

  See Also:

  • ProtectionDomain

• desiredAssertionStatus

  public boolean desiredAssertionStatus()

  Returns the assertion status that would be assigned to thisclass if it were to be initialized at the time this method is invoked.If this class has had its assertion status set, the most recentsetting will be returned; otherwise, if any package default assertionstatus pertains to this class, the most recent setting for the mostspecific pertinent package default assertion status is returned;otherwise, if this class is not a system class (i.e., it has aclass 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 providedfor the benefit of the JDK itself. (It allows a class to determine atthe time that it is initialized whether assertions should be enabled.)Note that this method is not guaranteed to return the actualassertion status that was (or will be) associated with the specifiedclass when it was (or will be) initialized.

  Returns:

  the desired assertion status of the specified class.

  Since:

  1.4

  See Also:

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

• isEnum

  public boolean isEnum()

  Returns true if and only if this class was declared as an enum in thesource code.Note thatEnum 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 classandnot the class of the declaring enum class. TheEnum.getDeclaringClass() method of an enum constant canbe used to get the class of the enum class declaring theconstant.

  Returns:

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

  SeeJava Language Specification:

  8.9.1 Enum Constants
  

  Since:

  1.5

• isRecord

  public boolean isRecord()

  Returnstrue if and only if this class is a record class.

  Thedirect superclass of a recordclass isjava.lang.Record. A record class isfinal. A record class has (possibly zero) recordcomponents;getRecordComponents() returns a non-null butpossibly empty value for a record.

  Note that classRecord is not a record class and thusinvoking this method on classRecord returnsfalse.

  Returns:

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

  SeeJava Language Specification:

  8.10 Record Classes
  

  Since:

  16

• getEnumConstants

  public T[] getEnumConstants()

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

  Returns:

  an array containing the values comprising the enum class represented by thisClass object in the order they're declared, or null if thisClass object does not represent an enum class

  SeeJava Language Specification:

  8.9.1 Enum Constants
  

  Since:

  1.5

• cast

  public T cast(Object obj)

  Casts an object to the class or interface representedby thisClass object.

  Parameters:

  obj - the object to be cast

  Returns:

  the object after casting, or null if obj is null

  Throws:

  ClassCastException - if the object is notnull and is not assignable to the type T.

  Since:

  1.5

• asSubclass

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

  Casts thisClass object to represent a subclass of the classrepresented by the specified class object. Checks that the castis valid, and throws aClassCastException if it is not. Ifthis method succeeds, it always returns a reference to thisClass object.

  This method is useful when a client needs to "narrow" the type ofaClass object to pass it to an API that restricts theClass objects that it is willing to accept. A cast wouldgenerate a compile-time warning, as the correctness of the castcould not be checked at runtime (because generic types are implementedby erasure).

  Type Parameters:

  U - the type to cast thisClass object to

  Parameters:

  clazz - the class of the type to cast thisClass object to

  Returns:

  thisClass object, cast to represent a subclass of the specified class object.

  Throws:

  ClassCastException - if thisClass object does not represent a subclass of the specified class (here "subclass" includes the class itself).

  Since:

  1.5

• getAnnotation

  public <A extendsAnnotation> A getAnnotation(Class<A> annotationClass)

  Returns this element's annotation for the specified type ifsuch an annotation ispresent, else null.

  Note that any annotation returned by this method is adeclaration annotation.

  Specified by:

  getAnnotation in interface AnnotatedElement

  Type Parameters:

  A - the type of the annotation to query for and return if present

  Parameters:

  annotationClass - the Class object corresponding to the annotation type

  Returns:

  this element's annotation for the specified annotation type if present on this element, else null

  Throws:

  NullPointerException - if the given annotation class is null

  Since:

  1.5

• isAnnotationPresent

  public boolean isAnnotationPresent(Class<? extendsAnnotation> annotationClass)

  Returns true if an annotation for the specified typeispresent on this element, else false. This methodis designed primarily for convenient access to marker annotations.

  The truth value returned by this method is equivalent to:getAnnotation(annotationClass) != null

  Specified by:

  isAnnotationPresent in interface AnnotatedElement

  Parameters:

  annotationClass - the Class object corresponding to the annotation type

  Returns:

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

  Throws:

  NullPointerException - if the given annotation class is null

  Since:

  1.5

• getAnnotationsByType

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

  Returns annotations that areassociated with this element.If there are no annotationsassociated with this element, the returnvalue is an array of length 0.The difference between this method andAnnotatedElement.getAnnotation(Class)is that this method detects if its argument is arepeatableannotation type (JLS9.6), and if so, attempts to find one ormore annotations of that type by "looking through" a containerannotation.The caller of this method is free to modify the returned array; it willhave no effect on the arrays returned to other callers.

  Note that any annotations returned by this method aredeclaration annotations.

  Specified by:

  getAnnotationsByType in interface AnnotatedElement

  Type Parameters:

  A - the type of the annotation to query for and return if present

  Parameters:

  annotationClass - the Class object corresponding to the annotation type

  Returns:

  all this element's annotations for the specified annotation type if associated with this element, else an array of length zero

  Throws:

  NullPointerException - if the given annotation class is null

  Since:

  1.8

• getAnnotations

  public Annotation[] getAnnotations()

  Returns annotations that arepresent on this element.If there are no annotationspresent on this element, the returnvalue is an array of length 0.The caller of this method is free to modify the returned array; it willhave no effect on the arrays returned to other callers.

  Note that any annotations returned by this method aredeclaration annotations.

  Specified by:

  getAnnotations in interface AnnotatedElement

  Returns:

  annotations present on this element

  Since:

  1.5

• getDeclaredAnnotation

  public <A extendsAnnotation> A getDeclaredAnnotation(Class<A> annotationClass)

  Returns this element's annotation for the specified type ifsuch an annotation isdirectly present, else null.This method ignores inherited annotations. (Returns null if noannotations are directly present on this element.)

  Note that any annotation returned by this method is adeclaration annotation.

  Specified by:

  getDeclaredAnnotation in interface AnnotatedElement

  Type Parameters:

  A - the type of the annotation to query for and return if directly present

  Parameters:

  annotationClass - the Class object corresponding to the annotation type

  Returns:

  this element's annotation for the specified annotation type if directly present on this element, else null

  Throws:

  NullPointerException - if the given annotation class is null

  Since:

  1.8

• getDeclaredAnnotationsByType

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

  Returns this element's annotation(s) for the specified type ifsuch annotations are eitherdirectly present orindirectly present. This method ignores inheritedannotations.If there are no specified annotations directly or indirectlypresent on this element, the return value is an array of length0.The difference between this method andAnnotatedElement.getDeclaredAnnotation(Class) is that this method detects if itsargument is arepeatable annotation type (JLS9.6), and if so,attempts to find one or more annotations of that type by "lookingthrough" a container annotation if one is present.The caller of this method is free to modify the returned array; it willhave no effect on the arrays returned to other callers.

  Note that any annotations returned by this method aredeclaration annotations.

  Specified by:

  getDeclaredAnnotationsByType in interface AnnotatedElement

  Type Parameters:

  A - the type of the annotation to query for and returnif directly or indirectly present

  Parameters:

  annotationClass - the Class object corresponding to the annotation type

  Returns:

  all this element's annotations for the specified annotation type if directly or indirectly present on this element, else an array of length zero

  Throws:

  NullPointerException - if the given annotation class is null

  Since:

  1.8

• getDeclaredAnnotations

  public Annotation[] getDeclaredAnnotations()

  Returns annotations that aredirectly present on this element.This method ignores inherited annotations.If there are no annotationsdirectly 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 willhave no effect on the arrays returned to other callers.

  Note that any annotations returned by this method aredeclaration annotations.

  Specified by:

  getDeclaredAnnotations in interface AnnotatedElement

  Returns:

  annotations directly present on this element

  Since:

  1.5

• getAnnotatedSuperclass

  public AnnotatedType getAnnotatedSuperclass()

  Returns anAnnotatedType object that represents the use of atype to specify the superclass of the entity represented by thisClass object. (Theuse of type Foo to specify the superclassin '... extends Foo' is distinct from thedeclaration of classFoo.)

  If thisClass object represents a class whose declarationdoes not explicitly indicate an annotated superclass, then the returnvalue is anAnnotatedType object representing an element with noannotations.

  If thisClass represents either theObject class, aninterface type, an array type, a primitive type, or void, the returnvalue isnull.

  Returns:

  an object representing the superclass

  Since:

  1.8

• getAnnotatedInterfaces

  public AnnotatedType[] getAnnotatedInterfaces()

  Returns an array ofAnnotatedType objects that represent the useof types to specify superinterfaces of the entity represented by thisClass object. (Theuse of type Foo to specify asuperinterface in '... implements Foo' is distinct from thedeclaration of interface Foo.)

  If thisClass object represents a class, the return value isan array containing objects representing the uses of interface types tospecify interfaces implemented by the class. The order of the objects inthe array corresponds to the order of the interface types used in the'implements' clause of the declaration of thisClass object.

  If thisClass object represents an interface, the returnvalue is an array containing objects representing the uses of interfacetypes to specify interfaces directly extended by the interface. Theorder of the objects in the array corresponds to the order of theinterface types used in the 'extends' clause of the declaration of thisClass object.

  If thisClass object represents a class or interface whosedeclaration does not explicitly indicate any annotated superinterfaces,the return value is an array of length 0.

  If thisClass object represents either theObjectclass, an array type, a primitive type, or void, the return value is anarray of length 0.

  Returns:

  an array representing the superinterfaces

  Since:

  1.8

• getNestHost

  public Class<?> getNestHost()

  Returns the nest host of thenest to which the classor interface represented by thisClass object belongs.Every class and interface belongs to exactly one nest.If the nest host of this class or interface has previouslybeen determined, then this method returns the nest host.If the nest host of this class or interface hasnot previously been determined, then this method determines the nesthost 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 returnsthis to indicate that the classor interface is the nest host.

  If thisClass object represents a primitive type, an array type,orvoid, then this method returnsthis,indicating that the represented entity belongs to the nest consisting only ofitself, and is the nest host.

  Returns:

  the nest host of this class or interface

  SeeJava Virtual Machine Specification:

  4.7.28 TheNestHost Attribute
  4.7.29 TheNestMembers Attribute
  5.4.4 Access Control
  

  Since:

  11

• isNestmateOf

  public boolean isNestmateOf(Class<?> c)

  Determines if the givenClass is a nestmate of theclass or interface represented by thisClass object.Two classes or interfaces are nestmatesif they have the samenest host.

  Parameters:

  c - the class to check

  Returns:

  true if this class andc are members ofthe same nest; andfalse otherwise.

  Since:

  11

• getNestMembers

  public Class<?>[] getNestMembers()

  Returns an array containingClass objects representing all theclasses and interfaces that are members of the nest to which the classor interface represented by thisClass object belongs.First, this method obtains thenest host,H, of the nest to which the class or interface represented bythisClass object belongs. The zeroth element of the returnedarray isH.Then, for each class or interfaceC which is recorded byHas being a member of its nest, this method attempts to obtain theClassobject forC (usingthe defining classloader of the currentClass object), and then obtains thenest host of the nest to whichC belongs.The classes and interfaces which are recorded byH as being membersof its nest, and for whichH can be determined as their nest host,are indicated by subsequent elements of the returned array. The order ofsuch elements is unspecified. Duplicates are permitted.

  If thisClass object represents a primitive type, an array type,orvoid, then this method returns a single-element array containingthis.

  API Note:

  The returned array includes only the nest members recorded in theNestMembersattribute, and not any hidden classes that were added to the nest viaLookup::defineHiddenClass.

  Returns:

  an array of all classes and interfaces in the same nest asthis class or interface

  SeeJava Virtual Machine Specification:

  4.7.28 TheNestHost Attribute
  4.7.29 TheNestMembers Attribute
  

  Since:

  11

  See Also:

  • getNestHost()

• descriptorString

  public String descriptorString()

  Returns the descriptor string of the entity (class, interface, array class,primitive type, orvoid) represented by thisClass object.

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

  • If the class or interface is nothidden, then the result is a field descriptor (JVMS4.3.2) for the class or interface. CallingClassDesc::ofDescriptor with the result descriptor string produces aClassDesc describing this class or interface.
  • If the class or interface ishidden, then the result is a string of the form:

    "L" +N+ "." + <suffix> + ";"

    whereN is thebinary name encoded in internal form indicated by theclass file passed toLookup::defineHiddenClass, and<suffix> is an unqualified name. A hidden class or interface has nonominal descriptor. The result string is not a type descriptor.

  If thisClass object represents an array class, thenthe result is a string consisting of one or more '[' charactersrepresenting the depth of the array nesting, followed by thedescriptor string of the element type.

  • If the element type is not ahidden classor interface, then this array class can be described nominally.CallingClassDesc::ofDescriptorwith the result descriptor string produces aClassDescdescribing this array class.
  • If the element type is ahidden class orinterface, then this array class cannot be described nominally.The result string is not a type descriptor.

  If thisClass object represents a primitive type orvoid, then the result is a field descriptor string whichis a one-letter code corresponding to a primitive type orvoid("B", "C", "D", "F", "I", "J", "S", "Z", "V") (JVMS4.3.2).

  Specified by:

  descriptorString in interface TypeDescriptor

  Returns:

  the descriptor string for thisClass object

  SeeJava Virtual Machine Specification:

  4.3.2 Field Descriptors
  

  Since:

  12

• componentType

  public Class<?> componentType()

  Returns the component type of thisClass, if it describesan array type, ornull otherwise.

  Specified by:

  componentType in interface TypeDescriptor.OfField<T>

  Implementation Requirements:

  Equivalent togetComponentType().

  Returns:

  aClass describing the component type, ornullif thisClass does not describe an array type

  Since:

  12

• arrayType

  public Class<?> arrayType()

  Returns aClass for an array type whose component typeis described by thisClass.

  Specified by:

  arrayType in interface TypeDescriptor.OfField<T>

  Returns:

  aClass describing the array type

  Throws:

  UnsupportedOperationException - if this component type isvoid or if the number of dimensions of the resulting array type would exceed 255.

  SeeJava Virtual Machine Specification:

  4.3.2 Field Descriptors
  4.4.1 TheCONSTANT_Class_info Structure
  

  Since:

  12

• describeConstable

  public Optional<ClassDesc> describeConstable()

  Returns a nominal descriptor for this instance, if one can beconstructed, or an emptyOptional if one cannot be.

  Specified by:

  describeConstable in interface Constable

  Returns:

  AnOptional containing the resulting nominal descriptor,or an emptyOptional if one cannot be constructed.

  Since:

  12

• isHidden

  public boolean isHidden()

  Returnstrue if and only if the underlying class is a hidden class.

  Returns:

  true if and only if this class is a hidden class.

  Since:

  15

  See Also:

  • MethodHandles.Lookup.defineHiddenClass(byte[], boolean, MethodHandles.Lookup.ClassOption...)
  • Hidden Classes

• getPermittedSubclasses

  public Class<?>[] getPermittedSubclasses()

  Returns an array containingClass objects representing thedirect subinterfaces or subclasses permitted to extend orimplement this class or interface if it is sealed. The order of such elementsis unspecified. The array is empty if this sealed class or interface has nopermitted subclass. If thisClass object represents a primitive type,void, an array type, or a class or interface that is not sealed,that isisSealed() returnsfalse, then this method returnsnull.Conversely, ifisSealed() returnstrue, then this methodreturns a non-null value.For each class or interfaceC which is recorded as a permitteddirect subinterface or subclass of this class or interface,this method attempts to obtain theClassobject forC (usingthe defining classloader of the currentClass object).TheClass objects which can be obtained and which are directsubinterfaces or subclasses of this class or interface,are indicated by elements of the returned array. If aClass objectcannot be obtained, it is silently ignored, and not included in the resultarray.

  Returns:

  an array ofClass objects of the permitted subclasses of this class or interface, ornull if this class or interface is not sealed.

  SeeJava Language Specification:

  8.1 Class Declarations
  9.1 Interface Declarations
  

  Since:

  17

• isSealed

  public boolean isSealed()

  Returnstrue if and only if thisClass object representsa sealed class or interface. If thisClass object represents aprimitive type,void, or an array type, this method returnsfalse. A sealed class or interface has (possibly zero) permittedsubclasses;getPermittedSubclasses() returns a non-null butpossibly empty value for a sealed class or interface.

  Returns:

  true if and only if thisClass object representsa sealed class or interface.

  SeeJava Language Specification:

  8.1 Class Declarations
  9.1 Interface Declarations
  

  Since:

  17