Class Class<T>

java.lang.Object
java.lang.Class<T>
Type Parameters:
T - the type of the class modeled by thisClass object. For example, the type ofString.class is Class<String>. UseClass<?> if the class being modeled is unknown.
All Implemented Interfaces:
Serializable,Constable,TypeDescriptor,TypeDescriptor.OfField<Class<?>>,AnnotatedElement,GenericDeclaration,Type
public final classClass<T>extendsObjectimplementsSerializable,GenericDeclaration,Type,AnnotatedElement,TypeDescriptor.OfField<Class<?>>,Constable
Instances of the classClass 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 aClass 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, anddouble), and the keywordvoid are also represented asClass objects.

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

The methods of classClass expose many characteristics of a class or interface. Most characteristics are derived from theclass file that the class loader passed to the Java Virtual Machine or from theclass file passed toLookup::defineClass orLookup::defineHiddenClass. A few characteristics are determined by the class loading environment at run time, such as the module returned bygetModule().

The following example uses aClass 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 theClass object for a named class or interface (or forvoid) using aclass literal (JLS15.8.2). For example:
System.out.println("The name of class Foo is: " +Foo.class.getName());

Some methods of classClass expose whether the declaration of a class or interface in Java source code wasenclosed within another declaration. Other methods describe how a class or interface is situated in anest. A nest is a set of classes and interfaces, in the same run-time package, that allow mutual access to theirprivate members. The classes and interfaces are known asnestmates (JVMS4.7.29). One nestmate acts as thenest host (JVMS4.7.28), 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 whenclass 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.

Hidden Classes

A class or interface created by the invocation ofLookup::defineHiddenClass is ahidden class or interface. All kinds of class, including enum classes and record classes, may be hidden classes; all kinds of interface, including annotation interfaces, may be hidden interfaces. Thename of a hidden class or interface is not abinary name, which means the following: A hidden class or interface is never an array class, but may be the element type of an array. In all other respects, the fact that a class or interface is hidden has no bearing on the characteristics exposed by the methods of classClass.

Implicitly Declared Classes

Conventionally, a Java compiler, starting from a source file for an implicitly declared class, sayHelloWorld.java, creates a similarly-namedclass file,HelloWorld.class, where the class stored in thatclass file is named "HelloWorld", matching the base names of the source and class files. For theClass object of an implicitly declared class HelloWorld, the methods to get thename andtype name return results equal to"HelloWorld". Thesimple name of such an implicitly declared class is"HelloWorld" and thecanonical name is"HelloWorld".
Since:
1.0
See Also:

  • Nested Class Summary

    Nested classes/interfaces declared in interface java.lang.invoke.TypeDescriptor

    TypeDescriptor.OfField<F extendsTypeDescriptor.OfField<F>>,TypeDescriptor.OfMethod<F extendsTypeDescriptor.OfField<F>,M extendsTypeDescriptor.OfMethod<F,M>>

  • Method Summary

    Modifier and Type
    Method
    Description
    Returns an unmodifiable set of theaccess flags for this class, possibly empty.
    Returns aClass for an array type whose component type is described by thisClass.
    <U> Class<? extends U>
    asSubclass(Class<U> clazz)
    Casts thisClass object to represent a subclass of the class represented by the specified class object.
    cast(Object obj)
    Casts an object to the class or interface represented by thisClass object.
    Returns the component type of thisClass, if it describes an array type, ornull otherwise.
    Returns a nominal descriptor for this instance, if one can be constructed, or an emptyOptional if one cannot be.
    Returns the descriptor string of the entity (class, interface, array class, primitive type, orvoid) represented by thisClass object.
    boolean
    Returns the assertion status that would be assigned to this class if it were to be initialized at the time this method is invoked.
    staticClass<?>
    forName(Module module,String name)
    Returns theClass with the givenbinary name in the given module.
    staticClass<?>
    forName(String className)
    Returns theClass object associated with the class or interface with the given string name.
    staticClass<?>
    forName(String name, boolean initialize,ClassLoader loader)
    Returns theClass object associated with the class or interface with the given string name, using the given class loader.
    staticClass<?>
    forPrimitiveName(String primitiveName)
    Returns theClass object associated with theprimitive type of the given name.
    Returns an array ofAnnotatedType objects that represent the use of types to specify superinterfaces of the entity represented by thisClass object.
    Returns anAnnotatedType object that represents the use of a type to specify the superclass of the entity represented by this Class object.
    <A extendsAnnotation>
    A
    getAnnotation(Class<A> annotationClass)
    Returns this element's annotation for the specified type if such an annotation ispresent, else null.
    Returns annotations that arepresent on this element.
    <A extendsAnnotation>
    A[]
    getAnnotationsByType(Class<A> annotationClass)
    Returns annotations that areassociated with this element.
    Returns the canonical name of the underlying class as defined byThe Java Language Specification.
    Class<?>[]
    Returns an array containingClass objects representing all the public classes and interfaces that are members of the class represented by thisClass object.
    Returns the class loader for the class.
    Returns theClass representing the component type of an array.
    getConstructor(Class<?>... parameterTypes)
    Returns aConstructor object that reflects the specified public constructor of the class represented by thisClass object.
    Returns an array containingConstructor objects reflecting all the public constructors of the class represented by thisClass object.
    <A extendsAnnotation>
    A
    getDeclaredAnnotation(Class<A> annotationClass)
    Returns this element's annotation for the specified type if such an annotation isdirectly present, else null.
    Returns annotations that aredirectly present on this element.
    <A extendsAnnotation>
    A[]
    getDeclaredAnnotationsByType(Class<A> annotationClass)
    Returns this element's annotation(s) for the specified type if such annotations are eitherdirectly present orindirectly present.
    Class<?>[]
    Returns an array ofClass objects reflecting all the classes and interfaces declared as members of the class represented by thisClass object.
    getDeclaredConstructor(Class<?>... parameterTypes)
    Returns aConstructor object that reflects the specified constructor of the class represented by thisClass object.
    Returns an array ofConstructor objects reflecting all the constructors implicitly or explicitly declared by the class represented by thisClass object.
    Returns aField object that reflects the specified declared field of the class or interface represented by thisClass object.
    Returns an array ofField objects reflecting all the fields declared by the class or interface represented by thisClass object.
    getDeclaredMethod(String name,Class<?>... parameterTypes)
    Returns aMethod object that reflects the specified declared method of the class or interface represented by thisClass object.
    Returns an array containingMethod 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.
    If the class or interface represented by thisClass object is a member of another class, returns theClass object representing the class in which it was declared.
    Returns the immediately enclosing class of the underlying class.
    If thisClass object represents a local or anonymous class within a constructor, returns aConstructor object representing the immediately enclosing constructor of the underlying class.
    If thisClass object represents a local or anonymous class within a method, returns aMethod object representing the immediately enclosing method of the underlying class.
    T[]
    Returns the elements of this enum class or null if this Class object does not represent an enum class.
    Returns aField object that reflects the specified public member field of the class or interface represented by thisClass object.
    Returns an array containingField objects reflecting all the accessible public fields of the class or interface represented by thisClass object.
    Returns theTypes representing the interfaces directly implemented by the class or interface represented by thisClass object.
    Returns theType representing the direct superclass of the entity (class, interface, primitive type or void) represented by thisClass object.
    Class<?>[]
    Returns the interfaces directly implemented by the class or interface represented by thisClass object.
    getMethod(String name,Class<?>... parameterTypes)
    Returns aMethod object that reflects the specified public member method of the class or interface represented by thisClass object.
    Returns an array containingMethod 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
    Returns the Java language modifiers for this class or interface, encoded in an integer.
    Returns the module that this class or interface is a member of.
    Returns the name of the entity (class, interface, array class, primitive type, or void) represented by thisClass object.
    Returns the nest host of thenest to which the class or interface represented by thisClass object belongs.
    Class<?>[]
    Returns an array containingClass objects representing all the classes and interfaces that are members of the nest to which the class or interface represented by thisClass object belongs.
    Gets the package of this class.
    Returns the fully qualified package name.
    Class<?>[]
    Returns an array containingClass objects representing the direct subinterfaces or subclasses permitted to extend or implement this class or interface if it is sealed.
    Returns theProtectionDomain of this class.
    Returns an array ofRecordComponent objects representing all the record components of this record class, ornull if this class is not a record class.
    Finds a resource with a given name.
    Finds a resource with a given name.
    Gets the signers of this class.
    Returns the simple name of the underlying class as given in the source code.
    Class<? superT>
    Returns theClass representing the direct superclass of the entity (class, interface, primitive type or void) represented by thisClass.
    Return an informative string for the name of this class or interface.
    Returns an array ofTypeVariable objects that represent the type variables declared by the generic declaration represented by thisGenericDeclaration object, in declaration order.
    boolean
    Returns true if thisClass object represents an annotation interface.
    boolean
    isAnnotationPresent(Class<? extendsAnnotation> annotationClass)
    Returns true if an annotation for the specified type ispresent on this element, else false.
    boolean
    Returnstrue if and only if the underlying class is an anonymous class.
    boolean
    Determines if thisClass object represents an array class.
    boolean
    Determines if the class or interface represented by thisClass object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specifiedClass parameter.
    boolean
    Returns true if and only if this class was declared as an enum in the source code.
    boolean
    Returnstrue if and only if the underlying class is a hidden class.
    boolean
    Determines if the specifiedObject is assignment-compatible with the object represented by thisClass.
    boolean
    Determines if thisClass object represents an interface type.
    boolean
    Returnstrue if and only if the underlying class is a local class.
    boolean
    Returnstrue if and only if the underlying class is a member class.
    boolean
    Determines if the givenClass is a nestmate of the class or interface represented by thisClass object.
    boolean
    Determines if thisClass object represents a primitive type or void.
    boolean
    Returnstrue if and only if this class is a record class.
    boolean
    Returnstrue if and only if thisClass object represents a sealed class or interface.
    boolean
    Returnstrue if and only if this class has the synthetic modifier bit set.
    Deprecated.
    This method propagates any exception thrown by the nullary constructor, including a checked exception.
    Returns a string describing thisClass, including information about modifiers,sealed/ non-sealed status, and type parameters.
    Converts the object to a string.

    Methods declared in class java.lang.Object

    clone,equals,finalize,getClass,hashCode,notify,notifyAll,wait,wait,wait

  • Method Details

    • toString

      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 bygetName. If thisClass object represents a primitive type, this method returns the name of the primitive type. If thisClass 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, including information 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 types andclass,enum,interface,@interface, orrecord as appropriate), followed by the type's name, followed by an angle-bracketed comma-separated list of the type's type parameters, if any, including informative bounds on the type parameters, if any. A space is used to separate modifiers from one another and to separate any modifiers from the kind of type. The modifiers occur in canonical order. If there are no type parameters, the type parameter list is elided. For an array type, the string starts with the type name, followed by an angle-bracketed comma-separated list of the type's type parameters, if any, followed by a sequence of[] characters, one set of brackets per dimension of the array.

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

      Returns:
      a string describing thisClass, including information about modifiers and type parameters
      Since:
      1.8

    • forName

      public static Class<?> forName(String className) throwsClassNotFoundException
      Returns theClass object associated with the class or interface with the given string name. Invoking this method is equivalent to:
      Class.forName(className, true, currentLoader)
      wherecurrentLoader denotes the defining class loader of the current class.

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

      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 no caller frame on the stack (e.g. when called directly from a JNI attached 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 or interface 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 specified class loader is used to load the class or interface. If the parameterloader isnull, the class is loaded through the bootstrap class loader. The class is initialized only if theinitialize parameter istrue and if it has not been initialized earlier.

      This method cannot be used to obtain any of theClass objects representing 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 package whose name isI instead. To obtain aClass object for a named primitive type such asint orlong useforPrimitiveName(String).

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

      Examples:

      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 returned fromforName(N) returnsN.

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

      API Note:
      This method throws errors related to loading, linking or initializing as specified in Sections12.2,12.3, and12.4 ofThe Java Language Specification. In addition, this method does not check whether the requested class is 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

      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 and the given name is a class defined in a different module, this method returnsnull after the class is loaded.

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

      API Note:
      This method does not support loading of array types, unlikeforName(String, boolean, ClassLoader). The class name must be a binary name. This method returnsnull on failure rather than throwing aClassNotFoundException, as is done by theforName(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.
      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. TheConstructor.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 typesInvocationTargetException andNoSuchMethodException. Both of these exception types are subclasses ofReflectiveOperationException.

      Creates a new instance of the class represented by thisClass object. The class is instantiated as if by anew expression with an empty argument list. The class is initialized if it has not already been initialized.
      Returns:
      a newly allocated instance of the class represented by this object.
      Throws:
      IllegalAccessException - if the class or its nullary constructor is not accessible.
      InstantiationException - if 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-compatible with the object represented by thisClass. This method is the dynamic equivalent of the Java languageinstanceof operator. The method returnstrue if the specifiedObject argument is non-null and can be cast to the reference type represented by thisClass object without raising aClassCastException. It returnsfalse otherwise.

      Specifically, if thisClass object represents a declared class, this method returnstrue if the specifiedObject argument is an instance of the represented class (or of any of its subclasses); it returnsfalse otherwise. If thisClass object represents an array class, this method returnstrue if the specifiedObject argument can be converted to an object of the array class by an identity conversion or by a widening reference conversion; it returnsfalse otherwise. If thisClass object represents an interface, this method returnstrue if the class or any superclass of the specifiedObject argument implements this interface; it returnsfalse otherwise. If thisClass object represents a primitive type, this method returnsfalse.

      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 or superinterface of, the class or interface represented by the specifiedClass parameter. It returnstrue if so; otherwise it returnsfalse. If thisClass object represents a primitive type, this method returnstrue if the specifiedClass parameter is exactly thisClass object; otherwise it returnsfalse.

      Specifically, this method tests whether the type represented by the specifiedClass parameter can be converted to the type represented by thisClass object via an identity conversion or via a widening reference conversion. SeeThe Java Language Specification, 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 an interface 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 primitive type or void.

      There are nine predefinedClass objects to represent the eight primitive types and void. These are created by the Java Virtual Machine, and have the samenames as the primitive types that they represent, 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 be accessed via theTYPE public static final variables defined in the primitive wrapper classes such asInteger.TYPE. In the Java programming language, the objects may be referred to by a class literal expression such asint.class. TheClass object for 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:

    • isAnnotation

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

    • 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, 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
      booleanZ
      byteB
      charC
      class or interface withbinary nameNLN;
      doubleD
      floatF
      intI
      longJ
      shortS

      If thisClass object represents a primitive type orvoid, then the result is a string with the same spelling as the Java language keyword 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 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 thisClass object represents a primitive type or void, null is returned.

      Returns:
      the class loader that loaded the class or interface represented by thisClass object.
      See Also:

    • 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 a primitive type or void, then theModule object for thejava.base module is returned. If this class is in an unnamed module then theunnamedModule of the class loader 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 the type variables declared by the generic declaration represented by thisGenericDeclaration object, in declaration order. Returns an array of length 0 if the underlying generic declaration declares no type variables.
      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 the entity (class, interface, primitive type or void) represented by thisClass. If thisClass represents either theObject class, an interface, a primitive type, or void, then null is returned. If thisClass object represents an array class then theClass object representing theObject class is returned.
      Returns:
      the direct superclass of the class represented by thisClass object

    • getGenericSuperclass

      public Type getGenericSuperclass()
      Returns theType representing the direct superclass of the entity (class, interface, primitive type or void) represented by thisClass object.

      If the superclass is a parameterized type, theType 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 ofParameterizedType for the semantics of the creation process for parameterized types. If thisClass object represents either theObject class, an interface, a primitive type, or void, then null is returned. If thisClass object represents an array class then theClass object representing theObject class is returned.

      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 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 invokinggetPackageName() on theenclosing class.

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

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

      Returns:
      the fully qualified package name
      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 interface represented by thisClass object.

      If thisClass 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 theimplements clause of the 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 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 theextends clause of the declaration of the interface represented by thisClass object.

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

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

      If thisClass object represents an array type, the interfacesCloneable andjava.io.Serializable are returned in that order.

      Returns:
      an array of interfaces directly implemented by this class

    • getGenericInterfaces

      public Type[] getGenericInterfaces()
      Returns theTypes representing the interfaces directly implemented by the class or interface represented by thisClass object.

      If a superinterface is a parameterized type, theType 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 ofParameterizedType for the semantics of the creation process for parameterized types.

      If thisClass 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 theimplements clause of the declaration of the class represented by thisClass object.

      If thisClass 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 theextends clause of the declaration of the interface represented by thisClass object.

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

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

      If thisClass object represents an array type, the interfacesCloneable andjava.io.Serializable are returned in that order.

      Returns:
      an array of interfaces directly implemented by this class
      Throws:
      GenericSignatureFormatError - if the generic class signature does not conform to the format specified in 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 an array. If this class does not represent an array class this method returns null.
      Returns:
      theClass representing the component type of this class if this class is an array
      Since:
      1.1
      See Also:

    • getModifiers

      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 forpublic,protected,private,final,static,abstract andinterface; they should be decoded using 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 or void, itspublic,abstract, andfinal modifiers are alwaystrue. ForClass objects representing void, primitive types, and arrays, the values of other modifiers arefalse other than as specified above.

      The modifier encodings are defined in section4.1 ofThe 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:

    • accessFlags

      public Set<AccessFlag> accessFlags()
      Returns an unmodifiable set of theaccess flags 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 or void, the flags arePUBLIC,ABSTRACT, andFINAL. ForClass objects representing void, primitive types, and arrays, access flags are absent other than as specified above.

      Returns:
      an unmodifiable set of theaccess flags for this class, possibly empty
      SeeJava Virtual Machine Specification:
      4.1 The ClassFile Structure
      4.7.6 The InnerClasses Attribute
      Since:
      20
      See Also:

    • 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 anonymous class within a method, returns aMethod object representing the immediately enclosing method of the underlying class. Returnsnull otherwise. In particular, this method returnsnull if the underlying class is a local or anonymous class immediately enclosed by a class or interface declaration, instance initializer or static initializer.
      Returns:
      the immediately enclosing method of the underlying class, if that class is a local or anonymous class; otherwisenull.
      Since:
      1.5

    • getEnclosingConstructor

      public Constructor<?> getEnclosingConstructor()
      If thisClass object represents a local or anonymous class within a constructor, returns aConstructor object representing the immediately enclosing constructor of the underlying class. Returnsnull otherwise. In particular, this method returnsnull if the underlying class is a local or anonymous class immediately enclosed by a class or interface declaration, instance initializer or static initializer.
      Returns:
      the immediately enclosing constructor of the underlying class, if that class is a local or anonymous class; otherwisenull.
      Since:
      1.5

    • getDeclaringClass

      public Class<?> getDeclaringClass()
      If the class or interface represented by thisClass object is a member of another class, returns theClass 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 thisClass object represents an array class, a primitive type, 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 underlying class. If the underlying class is a top level class this method 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 the source code. An empty string is returned if the underlying class isanonymous. Asynthetic class, one not present in source code, can have a non-empty name including special characters, such as "$".

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

      Returns:
      the simple name of the underlying class
      Since:
      1.5

    • 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 as defined byThe Java Language Specification. Returnsnull if the underlying class does not have a canonical name. Classes without canonical names include: The canonical name for a primitive class is the keyword for the corresponding primitive type (byte,short,char,int, and so on).

      An array type has a canonical name if and only if its component type has a canonical name. When an array type has a canonical name, it is equal to the canonical name of the component 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 class is 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 class is 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 class is 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 all the public classes and interfaces that are members of the class represented by thisClass 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 thisClass object has no public member classes or interfaces. This method also returns an array of length 0 if thisClass object represents a primitive type, an array class, 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 all the accessible public fields of the class or interface represented by thisClass object.

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

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

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

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

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

      Returns:
      the array 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 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 thisClass object represents an array type, then the returned array has aMethod object for each of the public methods inherited by the array type fromObject. It does not contain aMethod object forclone().

      If thisClass object represents an interface then the returned array does not contain any implicitly declared methods fromObject. Therefore, if no methods are explicitly declared in this interface or any of its superinterfaces then the returned array has length 0. (Note that aClass object which represents a class always 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 any particular 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 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 withbridge methods; the bridge method and the overriding method would have the same signature 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 reflecting all the public constructors of the class represented by thisClass 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<?>[] andnotConstructor<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 holdConstructor objects for different 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:

    • getField

      public Field getField(String name) throwsNoSuchFieldException
      Returns aField object that reflects the specified public member field of the class or interface represented by thisClass object. Thename parameter is aString 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 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 this method 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 public member 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 ofClass objects that identify the method's formal parameter types, in declared order. IfparameterTypes isnull, it is treated as if it were an empty array.

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

      If thisClass object represents an interface then this method does not find any implicitly declared method fromObject. 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 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(java.lang.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 withbridge 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 - 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 specified public constructor of the class represented by thisClass object. TheparameterTypes parameter is an array ofClass objects that identify the constructor's formal parameter types, in declared order. If thisClass 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 thisClass object whose formal parameter types 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:

    • getDeclaredClasses

      public Class<?>[] getDeclaredClasses()
      Returns an array ofClass objects reflecting all the classes and interfaces declared as members of the class represented by thisClass 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 thisClass object represents a primitive 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 fields declared 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 no declared fields, then this method returns an array of length 0.

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

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

      Returns:
      the array 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 the record components of this record class, ornull 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 isisRecord() returnsfalse, then this method returnsnull. Conversely, ifisRecord() returnstrue, 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:
      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 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 methodsnot in the source of the class or interface, includingbridge methods and othersynthetic methods added by compilers.

      If thisClass 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 aMethod object for each such method.

      If thisClass object represents a class or interface that has a class initialization method"<clinit>", then the returned array doesnot have a corresponding Method object.

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

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

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

      Returns:
      the array 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:

    • getDeclaredConstructors

      public Constructor<?>[] getDeclaredConstructors()
      Returns an array ofConstructor objects reflecting all the constructors 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 array returned are not sorted and are not in any particular order. If the class 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 thisClass object represents an interface, a primitive type, an array class, or void.
      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:

    • getDeclaredField

      public Field getDeclaredField(String name) throwsNoSuchFieldException
      Returns aField object that reflects the specified declared field of the class or interface represented by thisClass object. Thename parameter is aString that specifies the simple name of the desired field.

      If thisClass object represents an array type, then this method 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 specified declared method of the class or interface represented by thisClass object. Thename parameter is aString that specifies the simple name of the desired method, and theparameterTypes parameter is an array ofClass 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>" aNoSuchMethodException is raised.

      If thisClass object represents an array type, then this method 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 specified constructor of the class represented by thisClass object. TheparameterTypes parameter is an array ofClass objects that identify the constructor's formal parameter types, in declared order. If thisClass object represents an inner class declared in a non-static context, the formal parameter types include the explicit enclosing instance as the first parameter.
      Parameters:
      parameterTypes - the parameter array
      Returns:
      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:

    • getResourceAsStream

      public InputStream getResourceAsStream(String name)
      Finds a resource with a given name.

      If this class is in a namedModule then this method will attempt to find the resource in the module. This is done by delegating to the module's class loaderfindResource(String,String) method, invoking it with the module name and the absolute name of the resource. Resources in named modules are subject to the rules for encapsulation specified in theModulegetResourceAsStream method and so this method returnsnull when the resource is a non-".class" resource in a package that is not open to the caller's module.

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

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

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

        Where themodified_package_name is the package name of this object 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:

    • getResource

      public URL getResource(String name)
      Finds a resource with a given name.

      If this class is in a namedModule then this method will attempt to find the resource in the module. This is done by delegating to the module's class loaderfindResource(String,String) method, invoking it with the module name and the absolute name of the resource. Resources in named modules are subject to the rules for encapsulation specified in theModulegetResourceAsStream method and so this method returnsnull when the resource is a non-".class" resource in a package that is not open to the caller's module.

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

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

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

        Where themodified_package_name is the package name of this object 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:

    • desiredAssertionStatus

      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.
      Returns:
      the desired assertion status of the specified class.
      Since:
      1.4
      See Also:

    • isEnum

      public boolean isEnum()
      Returns true if and only if this class was declared as an enum in the source 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 class andnot the class of the declaring enum class. TheEnum.getDeclaringClass() method of an enum constant can be used to get the class of the enum class declaring the constant.
      Returns:
      true if and only if this class was declared as an enum in the source code
      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 record class isjava.lang.Record. A record class isfinal. A record class has (possibly zero) record components;getRecordComponents() returns a non-null but possibly empty value for a record.

      Note that classRecord is not a record class and thus invoking 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 this Class 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 represented by 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 not null 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 class represented by the specified class object. Checks that the cast is valid, and throws aClassCastException if it is not. If this method succeeds, it always returns a reference to thisClass object.

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

      Type Parameters:
      U - the type to cast 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 if such an annotation ispresent, else null.

      Note that any annotation returned by this method is a declaration 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 type ispresent on this element, else false. This method is designed primarily for convenient access to marker annotations.

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

      Specified by:
      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 return value is an array of length 0. The difference between this method andAnnotatedElement.getAnnotation(Class) is that this method detects if its argument is arepeatable annotation type (JLS9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.

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

      Specified by:
      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 return value is an array of length 0. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.

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

      Specified by:
      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 if such an annotation isdirectly present, else null. This method ignores inherited annotations. (Returns null if no annotations are directly present on this element.)

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

      Specified by:
      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 if such annotations are eitherdirectly present orindirectly present. This method ignores inherited annotations. If there are no specified annotations directly or indirectly present on this element, the return value is an array of length 0. The difference between this method andAnnotatedElement.getDeclaredAnnotation(Class) is that this method detects if its argument is arepeatable annotation type (JLS9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation if one is present. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.

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

      Specified by:
      getDeclaredAnnotationsByType in interface AnnotatedElement
      Type Parameters:
      A - the type of the annotation to query for and return if directly or indirectly present
      Parameters:
      annotationClass - the Class object corresponding to the annotation type
      Returns:
      all this element's annotations for the specified annotation type if directly or indirectly present on this element, else an array of length zero
      Throws:
      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 will have no effect on the arrays returned to other callers.

      Note that any annotations returned by this method are declaration 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 a type to specify the superclass of the entity represented by this Class object. (Theuse of type Foo to specify the superclass in '... extends Foo' is distinct from thedeclaration of class Foo.)

      If thisClass object represents a class whose declaration does not explicitly indicate an annotated superclass, then the return value is anAnnotatedType object representing an element with no annotations.

      If thisClass represents either theObject class, an interface type, an array type, a primitive type, or void, the return value isnull.

      Returns:
      an object representing the superclass
      Since:
      1.8

    • getAnnotatedInterfaces

      public AnnotatedType[] getAnnotatedInterfaces()
      Returns an array ofAnnotatedType objects that represent the use of types to specify superinterfaces of the entity represented by thisClass object. (Theuse of type Foo to specify a superinterface in '... implements Foo' is distinct from thedeclaration of interface Foo.)

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

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

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

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

      Returns:
      an array representing the superinterfaces
      Since:
      1.8

    • getNestHost

      public Class<?> getNestHost()
      Returns the nest host of thenest to which the class or 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 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 returnsthis to indicate that the class or 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 of itself, 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 the class or interface represented by thisClass object. Two classes or interfaces are nestmates if they have the samenest host.
      Parameters:
      c - the class to check
      Returns:
      true if this class andc are members of the same nest; andfalse otherwise.
      Since:
      11

    • getNestMembers

      public Class<?>[] getNestMembers()
      Returns an array containingClass objects representing all the classes and interfaces that are members of the nest to which the class or interface represented by thisClass object belongs. First, this method obtains thenest host,H, of the nest to which the class or interface represented by thisClass object belongs. The zeroth element of the returned array isH. Then, for each class or interfaceC which is recorded byH as being a member of its nest, this method attempts to obtain theClass object forC (usingthe defining class loader 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 members of its nest, and for whichH 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 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 theNestMembers attribute, 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 as this class or interface
      SeeJava Virtual Machine Specification:
      4.7.28 TheNestHost Attribute
      4.7.29 TheNestMembers Attribute
      Since:
      11
      See Also:

    • 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, then the result is a string consisting of one or more '[' characters representing the depth of the array nesting, followed by the descriptor string of the element type.

      • If the element type is not ahidden class or interface, then this array class can be described nominally. CallingClassDesc::ofDescriptor with the result descriptor string produces aClassDesc describing this array class.
      • If the element type is ahidden class or interface, 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 which is 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 describes an array type, ornull otherwise.
      Specified by:
      componentType in interface TypeDescriptor.OfField<T>
      Implementation Requirements:
      Equivalent togetComponentType().
      Returns:
      aClass describing the component type, ornull if thisClass does not describe an array type
      Since:
      12

    • arrayType

      public Class<?> arrayType()
      Returns aClass for an array type whose component type is 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 be constructed, 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:

    • getPermittedSubclasses

      public Class<?>[] getPermittedSubclasses()
      Returns an array containingClass 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 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 method returns a non-null value. For each class or interfaceC which is recorded as a permitted direct subinterface or subclass of this class or interface, this method attempts to obtain theClass object forC (usingthe defining class loader of the currentClass object). TheClass 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 aClass object cannot be obtained, it is silently ignored, and not included in the result array.
      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 represents a sealed class or interface. If thisClass object represents a primitive type,void, or an array type, this method returnsfalse. A sealed class or interface has (possibly zero) permitted subclasses;getPermittedSubclasses() returns a non-null but possibly empty value for a sealed class or interface.
      Returns:
      true if and only if thisClass object represents a sealed class or interface.
      SeeJava Language Specification:
      8.1 Class Declarations
      9.1 Interface Declarations
      Since:
      17