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public final class

Class

extends Object
implements Serializable AnnotatedElement GenericDeclaration Type
java.lang.Object
   ↳ java.lang.Class<T>

Class Overview

This class must be implemented by the VM vendor. The documented natives must be implemented to support other provided class implementations in this package. An instance of class Class is the in-image representation of a Java class. There are three basic types of Classes

Classes representing object types (classes or interfaces)
These are Classes which represent the class of a simple instance as found in the class hierarchy. The name of one of these Classes is simply the fully qualified class name of the class or interface that it represents. Its signature is the letter "L", followed by its name, followed by a semi-colon (";").
Classes representing base types
These Classes represent the standard Java base types. Although it is not possible to create new instances of these Classes, they are still useful for providing reflection information, and as the component type of array classes. There is one of these Classes for each base type, and their signatures are:
  • B representing the byte base type
  • S representing the short base type
  • I representing the int base type
  • J representing the long base type
  • F representing the float base type
  • D representing the double base type
  • C representing the char base type
  • Z representing the boolean base type
  • V representing void function return values
The name of a Class representing a base type is the keyword which is used to represent the type in Java source code (i.e. "int" for the int base type.
Classes representing array classes
These are Classes which represent the classes of Java arrays. There is one such Class for all array instances of a given arity (number of dimensions) and leaf component type. In this case, the name of the class is one or more left square brackets (one per dimension in the array) followed by the signature of the class representing the leaf component type, which can be either an object type or a base type. The signature of a Class representing an array type is the same as its name.

Summary

Public Methods
<U> Class<? extends U> asSubclass(Class<U> clazz)
Casts the receiver to a subclass of the given class.
T cast(Object obj)
Cast the given object to the type T.
boolean desiredAssertionStatus()
Returns the assertion status for this class.
static Class<?> forName(String className, boolean initializeBoolean, ClassLoader classLoader)
Returns a Class object which represents the class named by the argument.
static Class<?> forName(String className)
Returns a Class object which represents the class named by the argument.
<A extends Annotation> A getAnnotation(Class<A> annotationClass)
Returns the annotation of the given type.
Annotation[] getAnnotations()
Returns all the annotations of the receiver.
String getCanonicalName()
Returns the canonical name of the receiver.
ClassLoader getClassLoader()
Returns the class loader which was used to load the class represented by the receiver.
Class[]<?> getClasses()
Returns an array containing all public class members of the class which the receiver represents and its super classes and interfaces
Class<?> getComponentType()
Returns a Class object which represents the receiver's component type if the receiver represents an array type.
Constructor<T> getConstructor(Class... parameterTypes)
Returns a public Constructor object which represents the constructor described by the arguments.
Constructor[]<T> getConstructors()
Returns an array containing Constructor objects describing all constructors which are visible from the current execution context.
Annotation[] getDeclaredAnnotations()
Returns the annotations that are directly defined on this type.
Class[]<?> getDeclaredClasses()
Returns an array containing all class members of the class which the receiver represents.
Constructor<T> getDeclaredConstructor(Class... parameterTypes)
Returns a Constructor object which represents the constructor described by the arguments.
Constructor[]<T> getDeclaredConstructors()
Returns an array containing Constructor objects describing all constructor which are defined by the receiver.
Field getDeclaredField(String name)
Returns a Field object describing the field in the receiver named by the argument.
Field[] getDeclaredFields()
Returns an array containing Field objects describing all fields which are defined by the receiver.
Method getDeclaredMethod(String name, Class... parameterTypes)
Returns a Method object which represents the method described by the arguments.
Method[] getDeclaredMethods()
Returns an array containing Method objects describing all methods which are defined by the receiver.
Class<?> getDeclaringClass()
Returns the class which declared the class represented by the receiver.
Class<?> getEnclosingClass()
Returns the class that directly encloses the receiver.
Constructor<?> getEnclosingConstructor()
Gets the Constructor, which encloses the declaration of this class, if it is an anonymous or local/automatic class, otherwise null.
Method getEnclosingMethod()
Gets the Method, which encloses the declaration of this class, if it is an anonymous or local/automatic class, otherwise null.
T[] getEnumConstants()
Gets the enum constants/fields associated with this class if it is an enum, otherwise null.
Field getField(String name)
Returns a Field object describing the field in the receiver named by the argument which must be visible from the current execution context.
Field[] getFields()
Returns an array containing Field objects describing all fields which are visible from the current execution context.
Type[] getGenericInterfaces()
Gets the types of the interface that this class directly implements.
Type getGenericSuperclass()
Gets the Type that represents the super class of this class.
Class[]<?> getInterfaces()
Returns an array of Class objects which match the interfaces specified in the receiver classes implements declaration.
Method getMethod(String name, Class... parameterTypes)
Returns a Method object which represents the method described by the arguments.
Method[] getMethods()
Returns an array containing Method objects describing all methods which are visible from the current execution context.
int getModifiers()
Returns an integer which which is the receiver's modifiers.
String getName()
Returns the name of the class which the receiver represents.
Package getPackage()
Returns the Package of which this class is a member.
ProtectionDomain getProtectionDomain()
Returns the ProtectionDomain of the receiver.
URL getResource(String resName)
Returns a read-only stream on the contents of the resource specified by resName.
InputStream getResourceAsStream(String resName)
Returns a read-only stream on the contents of the resource specified by resName.
Object[] getSigners()
Returns the signers for the class represented by the receiver, or null if there are no signers.
String getSimpleName()
Returns the simple name of the receiver as defined in the source code.
Class<? super T> getSuperclass()
Returns the Class which represents the receiver's superclass.
synchronized TypeVariable[]<Class<T>> getTypeParameters()
Gets the type variables associated with this class.
boolean isAnnotation()
Indicates whether or not this class is an annotation.
boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)
Indicates whether or not the given annotation is present for this class.
boolean isAnonymousClass()
Indicates whether or not this class was anonymously declared.
boolean isArray()
Returns true if the receiver represents an array class.
boolean isAssignableFrom(Class<?> cls)
Returns true if the type represented by the argument can be converted via an identity conversion or a widening reference conversion (i.e.
boolean isEnum()
Indicates whether or not this class is an enum.
boolean isInstance(Object object)
Returns true if the argument is non-null and can be cast to the type of the receiver.
boolean isInterface()
Returns true if the receiver represents an interface.
boolean isLocalClass()
Returns whether the receiver is defined locally.
boolean isMemberClass()
Returns whether the receiver is a member class.
boolean isPrimitive()
Returns true if the receiver represents a base type.
boolean isSynthetic()
Returns whether the receiver is a synthetic type.
T newInstance()
Returns a new instance of the class represented by the receiver, created by invoking the default (i.e.
String toString()
Returns a string containing a concise, human-readable description of the receiver.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.lang.reflect.AnnotatedElement
From interface java.lang.reflect.GenericDeclaration

Public Methods

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

Casts the receiver to a subclass of the given class. If successful returns the receiver, otherwise if the cast cannot be made throws a ClassCastException.

Parameters
clazz the required type.
Returns
  • this class cast as a subclass of the given type.
Throws
ClassCastException if the class cannot be cast to the given type.

public T cast (Object obj)

Cast the given object to the type T. If the object is null the result is also null.

Parameters
obj the object to cast
Returns
  • The object that has been cast.
Throws
ClassCastException if the object cannot be cast to the given type.

public boolean desiredAssertionStatus ()

Returns the assertion status for this class. Assertion is enabled/disabled based on class loader default, package or class default at runtime

Returns
  • the assertion status for this class

public static Class<?> forName (String className, boolean initializeBoolean, ClassLoader classLoader)

Returns a Class object which represents the class named by the argument. The name should be the name of a class as described in the class definition of Class, however Classes representing base types can not be found using this method. Security rules will be obeyed.

Parameters
className The name of the non-base type class to find
initializeBoolean A boolean indicating whether the class should be initialized
classLoader The class loader to use to load the class
Returns
  • the named class.
Throws
ClassNotFoundException If the class could not be found
See Also

public static Class<?> forName (String className)

Returns a Class object which represents the class named by the argument. The name should be the name of a class as described in the class definition of Class, however Classes representing base types can not be found using this method.

Parameters
className The name of the non-base type class to find
Returns
  • the named Class
Throws
ClassNotFoundException If the class could not be found
See Also

public A getAnnotation (Class<A> annotationClass)

Returns the annotation of the given type. If there is no annotation the method returns null.

Parameters
annotationClass the annotation type.
Returns
  • the annotation of the given type, or null if none.

public Annotation[] getAnnotations ()

Returns all the annotations of the receiver. If there are no annotations then returns an empty array.

Returns
  • a copy of the array containing the receiver's annotations.

public String getCanonicalName ()

Returns the canonical name of the receiver. If the receiver does not have a canonical name, as defined in the Java Language Specification, then the method returns null.

Returns
  • the receiver canonical name, or null.

public ClassLoader getClassLoader ()

Returns the class loader which was used to load the class represented by the receiver. Returns null if the class was loaded by the bootstrap class loader

Returns
  • the receiver's class loader or nil
See Also

public Class[]<?> getClasses ()

Returns an array containing all public class members of the class which the receiver represents and its super classes and interfaces

Returns
  • the class' public class members
Throws
SecurityException If member access is not allowed
See Also

public Class<?> getComponentType ()

Returns a Class object which represents the receiver's component type if the receiver represents an array type. Otherwise returns nil. The component type of an array type is the type of the elements of the array.

Returns
  • the component type of the receiver.
See Also

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

Returns a public Constructor object which represents the constructor described by the arguments.

Parameters
parameterTypes the types of the arguments.
Returns
  • the constructor described by the arguments.
Throws
NoSuchMethodException if the constructor could not be found.
SecurityException if member access is not allowed
See Also

public Constructor[]<T> getConstructors ()

Returns an array containing Constructor objects describing all constructors which are visible from the current execution context.

Returns
  • all visible constructors starting from the receiver.
Throws
SecurityException if member access is not allowed
See Also

public Annotation[] getDeclaredAnnotations ()

Returns the annotations that are directly defined on this type. Annotations that are inherited are not included in the result. If there are no annotations, returns an empty array.

Returns
  • a copy of the array containing the receiver's defined annotations.

public Class[]<?> getDeclaredClasses ()

Returns an array containing all class members of the class which the receiver represents. Note that some of the fields which are returned may not be visible in the current execution context.

Returns
  • the class' class members
Throws
SecurityException if member access is not allowed
See Also

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

Returns a Constructor object which represents the constructor described by the arguments.

Parameters
parameterTypes the types of the arguments.
Returns
  • the constructor described by the arguments.
Throws
NoSuchMethodException if the constructor could not be found.
SecurityException if member access is not allowed
See Also

public Constructor[]<T> getDeclaredConstructors ()

Returns an array containing Constructor objects describing all constructor which are defined by the receiver. Note that some of the fields which are returned may not be visible in the current execution context.

Returns
  • the receiver's constructors.
Throws
SecurityException if member access is not allowed
See Also

public Field getDeclaredField (String name)

Returns a Field object describing the field in the receiver named by the argument. Note that the Constructor may not be visible from the current execution context.

Parameters
name The name of the field to look for.
Returns
  • the field in the receiver named by the argument.
Throws
NoSuchFieldException if the requested field could not be found
SecurityException if member access is not allowed
See Also

public Field[] getDeclaredFields ()

Returns an array containing Field objects describing all fields which are defined by the receiver. Note that some of the fields which are returned may not be visible in the current execution context.

Returns
  • the receiver's fields.
Throws
SecurityException If member access is not allowed
See Also

public Method getDeclaredMethod (String name, Class... parameterTypes)

Returns a Method object which represents the method described by the arguments. Note that the associated method may not be visible from the current execution context.

Parameters
name the name of the method
parameterTypes the types of the arguments.
Returns
  • the method described by the arguments.
Throws
NoSuchMethodException if the method could not be found.
SecurityException If member access is not allowed
NullPointerException if the name parameter is null.
See Also

public Method[] getDeclaredMethods ()

Returns an array containing Method objects describing all methods which are defined by the receiver. Note that some of the methods which are returned may not be visible in the current execution context.

Returns
  • the receiver's methods.
Throws
SecurityException if member access is not allowed
See Also

public Class<?> getDeclaringClass ()

Returns the class which declared the class represented by the receiver. This will return null if the receiver is a member of another class.

Returns
  • the declaring class of the receiver.

public Class<?> getEnclosingClass ()

Returns the class that directly encloses the receiver. If there is no enclosing class the method returns null.

Returns
  • the enclosing class or null.

public Constructor<?> getEnclosingConstructor ()

Gets the Constructor, which encloses the declaration of this class, if it is an anonymous or local/automatic class, otherwise null.

Returns

public Method getEnclosingMethod ()

Gets the Method, which encloses the declaration of this class, if it is an anonymous or local/automatic class, otherwise null.

Returns

public T[] getEnumConstants ()

Gets the enum constants/fields associated with this class if it is an enum, otherwise null.

Returns
  • An array of the enum constants for this class or null.

public Field getField (String name)

Returns a Field object describing the field in the receiver named by the argument which must be visible from the current execution context.

Parameters
name The name of the field to look for.
Returns
  • the field in the receiver named by the argument.
Throws
NoSuchFieldException If the given field does not exist
SecurityException If access is denied
See Also

public Field[] getFields ()

Returns an array containing Field objects describing all fields which are visible from the current execution context.

Returns
  • all visible fields starting from the receiver.
Throws
SecurityException If member access is not allowed
See Also

public Type[] getGenericInterfaces ()

Gets the types of the interface that this class directly implements.

Returns
  • An array of Type instances.

public Type getGenericSuperclass ()

Gets the Type that represents the super class of this class.

Returns

public Class[]<?> getInterfaces ()

Returns an array of Class objects which match the interfaces specified in the receiver classes implements declaration. The order of entries equals the order in the original class declaration. If the class doesn't implement any interfaces, an empty array is returned.

Returns
  • Class[] the interfaces the receiver claims to implement.

public Method getMethod (String name, Class... parameterTypes)

Returns a Method object which represents the method described by the arguments.

Parameters
name String the name of the method
parameterTypes Class[] the types of the arguments.
Returns
  • Method the method described by the arguments.
Throws
NoSuchMethodException if the method could not be found.
SecurityException if member access is not allowed
See Also

public Method[] getMethods ()

Returns an array containing Method objects describing all methods which are visible from the current execution context.

Returns
  • Method[] all visible methods starting from the receiver.
Throws
SecurityException if member access is not allowed
See Also

public int getModifiers ()

Returns an integer which which is the receiver's modifiers. Note that the constants which describe the bits which are returned are implemented in class Modifier which may not be available on the target.

Returns
  • the receiver's modifiers

public String getName ()

Returns the name of the class which the receiver represents. For a description of the format which is used, see the class definition of Class.

Returns
  • the receiver's name.
See Also

public Package getPackage ()

Returns the Package of which this class is a member. A class has a Package if it was loaded from a SecureClassLoader

Returns
  • Package the Package of which this class is a member or null

public ProtectionDomain getProtectionDomain ()

Returns the ProtectionDomain of the receiver.

Note: In order to conserve space in embedded targets, we allow this method to answer null for classes in the system protection domain (i.e. for system classes). System classes are always given full permissions (i.e. AllPermission). This is not changeable via the java.security.Policy.

Returns
  • ProtectionDomain the receiver's ProtectionDomain.
See Also

public URL getResource (String resName)

Returns a read-only stream on the contents of the resource specified by resName. The mapping between the resource name and the stream is managed by the class' class loader.

Parameters
resName the name of the resource.
Returns
  • a stream on the resource.
See Also

public InputStream getResourceAsStream (String resName)

Returns a read-only stream on the contents of the resource specified by resName. The mapping between the resource name and the stream is managed by the class' class loader.

Parameters
resName the name of the resource.
Returns
  • a stream on the resource.
See Also

public Object[] getSigners ()

Returns the signers for the class represented by the receiver, or null if there are no signers.

Returns
  • the signers of the receiver.
See Also

public String getSimpleName ()

Returns the simple name of the receiver as defined in the source code. If there is no name (the class is anonymous) returns an empty string, and if the receiver is an array returns the name of the underlying type with square braces appended (e.g. "Integer[]").

Returns
  • the simple name of the receiver.

public Class<? super T> getSuperclass ()

Returns the Class which represents the receiver's superclass. For Classes which represent base types, interfaces, and for Object the method returns null.

Returns
  • the receiver's superclass.

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

Gets the type variables associated with this class. Returns an empty array if the class is not generic or does not make use of type variables otherwise.

Returns

public boolean isAnnotation ()

Indicates whether or not this class is an annotation.

Returns
  • A value of true if this class is an annotation, otherwise false.

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

Indicates whether or not the given annotation is present for this class.

Parameters
annotationClass The annotation to look for in this class.
Returns
  • A value of true if the annotation is present, otherwise false.

public boolean isAnonymousClass ()

Indicates whether or not this class was anonymously declared.

Returns
  • A value of true if this class is anonymous, otherwise false.

public boolean isArray ()

Returns true if the receiver represents an array class.

Returns
  • true if the receiver represents an array class false if it does not represent an array class

public boolean isAssignableFrom (Class<?> cls)

Returns true if the type represented by the argument can be converted via an identity conversion or a widening reference conversion (i.e. if either the receiver or the argument represent primitive types, only the identity conversion applies).

Parameters
cls Class the class to test
Returns
  • true the argument can be assigned into the receiver false the argument cannot be assigned into the receiver
Throws
NullPointerException if the parameter is null

public boolean isEnum ()

Indicates whether or not this class is an enum.

Returns
  • A value of true if this class is an Enum, otherwise false.

public boolean isInstance (Object object)

Returns true if the argument is non-null and can be cast to the type of the receiver. This is the runtime version of the instanceof operator.

Parameters
object Object the object to test
Returns
  • true the argument can be cast to the type of the receiver false the argument is null or cannot be cast to the type of the receiver

public boolean isInterface ()

Returns true if the receiver represents an interface.

Returns
  • true if the receiver represents an interface false if it does not represent an interface

public boolean isLocalClass ()

Returns whether the receiver is defined locally.

Returns
  • true if the class is local, otherwise false.

public boolean isMemberClass ()

Returns whether the receiver is a member class.

Returns
  • true if the class is a member class, otherwise false.

public boolean isPrimitive ()

Returns true if the receiver represents a base type.

Returns
  • true if the receiver represents a base type false if it does not represent a base type

public boolean isSynthetic ()

Returns whether the receiver is a synthetic type.

Returns
  • true if the receiver is a synthetic type and false otherwise.

public T newInstance ()

Returns a new instance of the class represented by the receiver, created by invoking the default (i.e. zero-argument) constructor. If there is no such constructor, or if the creation fails (either because of a lack of available memory or because an exception is thrown by the constructor), an InstantiationException is thrown. If the default constructor exists, but is not accessible from the context where this message is sent, an IllegalAccessException is thrown.

Returns
  • a new instance of the class represented by the receiver.
Throws
IllegalAccessException if the constructor is not visible to the sender.
InstantiationException if the instance could not be created.

public String toString ()

Returns a string containing a concise, human-readable description of the receiver.

Returns
  • a printable representation for the receiver.