This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


java.lang
class Class

java.lang.Object extended by java.lang.Class
All Implemented Interfaces:
Serializable, AnnotatedElement, GenericDeclaration, Type

Most common way to construct:

Class cls = Class.forName("constructor1");

Based on 8 examples


public final class Class
extends Object
implements Serializable, GenericDeclaration, Type, AnnotatedElement

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

Class has no public constructor. Instead Class objects are constructed automatically by the Java Virtual Machine as classes are loaded and by calls to the defineClass method in the class loader.

The following example uses a Class object to print the class name of an object:

     void printClassName(Object obj) {
         System.out.println("The class of " + obj +
                            " is " + obj.getClass().getName());
     }
 

It is also possible to get the Class object for a named type (or for void) using a class literal (JLS Section 15.8.2). For example:

     System.out.println("The name of class Foo is: "+Foo.class.getName());
 


Method Summary
 Class

          Casts this Class object to represent a subclass of the class represented by the specified class object.
 Object
cast(Object obj)

          Casts an object to the class or interface represented by this Class 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.
static Class
forName(String className)

          Returns the Class object associated with the class or interface with the given string name.
static Class
forName(String name, boolean initialize, ClassLoader loader)

          Returns the Class object associated with the class or interface with the given string name, using the given class loader.
 Annotation
getAnnotation(Class annotationClass)

          
 Annotation[]

          
 String

          Returns the canonical name of the underlying class as defined by the Java Language Specification.
 Class[]

          Returns an array containing Class objects representing all the public classes and interfaces that are members of the class represented by this Class object.
 ClassLoader

          Returns the class loader for the class.
native Class

          Returns the Class representing the component type of an array.
 Constructor
getConstructor(Class[] parameterTypes)

          Returns a Constructor object that reflects the specified public constructor of the class represented by this Class object.
 Constructor[]

          Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object.
 Annotation[]

          
 Class[]

          Returns an array of Class objects reflecting all the classes and interfaces declared as members of the class represented by this Class object.
 Constructor
getDeclaredConstructor(Class[] parameterTypes)

          Returns a Constructor object that reflects the specified constructor of the class or interface represented by this Class object.
 Constructor[]

          Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.
 Field

          Returns a Field object that reflects the specified declared field of the class or interface represented by this Class object.
 Field[]

          Returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object.
 Method
getDeclaredMethod(String name, Class[] parameterTypes)

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

          Returns an array of Method objects reflecting all the methods declared by the class or interface represented by this Class object.
native Class

          If the class or interface represented by this Class object is a member of another class, returns the Class object representing the class in which it was declared.
 Class

          Returns the immediately enclosing class of the underlying class.
 Constructor

          If this Class object represents a local or anonymous class within a constructor, returns a java.lang.reflect.Constructor object representing the immediately enclosing constructor of the underlying class.
 Method

          If this Class object represents a local or anonymous class within a method, returns a java.lang.reflect.Method object representing the immediately enclosing method of the underlying class.
 Object[]

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

          Returns a Field object that reflects the specified public member field of the class or interface represented by this Class object.
 Field[]

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

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

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

          Determines the interfaces implemented by the class or interface represented by this object.
 Method
getMethod(String name, Class[] parameterTypes)

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

          Returns an array containing Method objects reflecting all the public member 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.
native int

          Returns the Java language modifiers for this class or interface, encoded in an integer.
 String

          Returns the name of the entity (class, interface, array class, primitive type, or void) represented by this Class object, as a String.
 Package

          Gets the package for this class.
 ProtectionDomain

          Returns the ProtectionDomain of this class.
 URL

          Finds a resource with a given name.
 InputStream

          Finds a resource with a given name.
native Object[]

          Gets the signers of this class.
 String

          Returns the simple name of the underlying class as given in the source code.
native Class

          Returns the Class representing the superclass of the entity (class, interface, primitive type or void) represented by this Class.
 TypeVariable[]

          Returns an array of TypeVariable objects that represent the type variables declared by the generic declaration represented by this GenericDeclaration object, in declaration order.
 boolean

          Returns true if this Class object represents an annotation type.
 boolean
isAnnotationPresent(Class annotationClass)

          
 boolean

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

          Determines if this Class object represents an array class.
native boolean

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

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

          Determines if the specified Object is assignment-compatible with the object represented by this Class.
native boolean

          Determines if the specified Class object represents an interface type.
 boolean

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

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

          Determines if the specified Class object represents a primitive type.
 boolean

          Returns true if this class is a synthetic class; returns false otherwise.
 Object

          Creates a new instance of the class represented by this Class object.
 String

          Converts the object to a string.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

asSubclass

public Class asSubclass(Class clazz)
Casts this Class object to represent a subclass of the class represented by the specified class object. Checks that that the cast is valid, and throws a ClassCastException if it is not. If this method succeeds, it always returns a reference to this class object.

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

Parameters:
clazz
Returns:
this Class object, cast to represent a subclass of the specified class object.

cast

public Object cast(Object obj)
Casts an object to the class or interface represented by this Class object.

Parameters:
obj - the object to be cast
Returns:
the object after casting, or null if obj is null

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.

Few programmers will have any need for this method; it is provided for the benefit of the JRE 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.

forName

public static Class forName(String className)
                     throws ClassNotFoundException
Returns the Class object associated with the class or interface with the given string name. Invoking this method is equivalent to:
  Class.forName(className, true, currentLoader)
 
where currentLoader denotes the defining class loader of the current class.

For example, the following code fragment returns the runtime Class descriptor for the class named java.lang.Thread:

   Class t = Class.forName("java.lang.Thread")
 

A call to forName("X") causes the class named X to be initialized.

Parameters:
className - the fully qualified name of the desired class.
Returns:
the Class object for the class with the specified name.
Throws:
ClassNotFoundException - if the class cannot be located

forName

public static Class forName(String name,
                            boolean initialize,
                            ClassLoader loader)
                     throws ClassNotFoundException
Returns the Class object associated with the class or interface with the given string name, using the given class loader. Given the fully qualified name for a class or interface (in the same format returned by getName) this method attempts to locate, load, and link the class or interface. The specified class loader is used to load the class or interface. If the parameter loader is null, the class is loaded through the bootstrap class loader. The class is initialized only if the initialize parameter is true and if it has not been initialized earlier.

If name denotes a primitive type or void, an attempt will be made to locate a user-defined class in the unnamed package whose name is name. Therefore, this method cannot be used to obtain any of the Class objects representing primitive types or void.

If name denotes an array class, the component type of the array class is loaded but not initialized.

For example, in an instance method the expression:

  Class.forName("Foo")
 
is equivalent to:
  Class.forName("Foo", true, this.getClass().getClassLoader())
 
Note that this method throws errors related to loading, linking or initializing as specified in Sections 12.2, 12.3 and 12.4 of The Java Language Specification. Note that this method does not check whether the requested class is accessible to its caller.

If the loader is null, and a security manager is present, and the caller's class loader is not null, then this method calls the security manager's checkPermission method with a RuntimePermission("getClassLoader") permission to ensure it's ok to access the bootstrap class loader.

Parameters:
name - fully qualified name of the desired class
initialize - whether the class must be initialized
loader - class loader from which the class must be loaded
Returns:
class object representing the desired class
Throws:
ClassNotFoundException - if the class cannot be located by the specified class loader

getAnnotation

public Annotation getAnnotation(Class annotationClass)
Parameters:
annotationClass

getAnnotations

public Annotation[] getAnnotations()

getCanonicalName

public String getCanonicalName()
Returns the canonical name of the underlying class as defined by the Java Language Specification. Returns null if the underlying class does not have a canonical name (i.e., if it is a local or anonymous class or an array whose component type does not have a canonical name).

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

getClasses

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

Returns:
the array of Class objects representing the public members of this class

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 a security manager is present, and the caller's class loader is not null and the caller's class loader is not the same as or an ancestor of the class loader for the class whose class loader is requested, then this method calls the security manager's checkPermission method with a RuntimePermission("getClassLoader") permission to ensure it's ok to access the class loader for the class.

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

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

getComponentType

public native Class getComponentType()
Returns the Class representing the component type of an array. If this class does not represent an array class this method returns null.

Returns:
the Class representing the component type of this class if this class is an array

getConstructor

public Constructor getConstructor(Class[] parameterTypes)
                           throws NoSuchMethodException,
                                  SecurityException
Returns a Constructor object that reflects the specified public constructor of the class represented by this Class object. The parameterTypes parameter is an array of Class objects that identify the constructor's formal parameter types, in declared order. If this Class object represents an inner class declared in a non-static context, the formal parameter types include the explicit enclosing instance as the first parameter.

The constructor to reflect is the public constructor of the class represented by this Class object whose formal parameter types match those specified by parameterTypes.

Parameters:
parameterTypes - the parameter array
Returns:
the Constructor object of the public constructor that matches the specified parameterTypes
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the constructor
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getConstructors

public Constructor[] getConstructors()
                              throws SecurityException
Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object. An array of length 0 is returned if the class has no public constructors, or if the class is an array class, or if the class reflects a primitive type or void. Note that while this method returns an array of {@code Constructor} objects (that is an array of constructors from this class), the return type of this method is {@code Constructor[]} and not {@code Constructor[]} as might be expected. This less informative return type is necessary since after being returned from this method, the array could be modified to hold {@code Constructor} objects for different classes, which would violate the type guarantees of {@code Constructor[]}.

Returns:
the array of Constructor objects representing the public constructors of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the constructors within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredAnnotations

public Annotation[] getDeclaredAnnotations()

getDeclaredClasses

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

Returns:
the array of Class objects representing all the declared members of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared classes within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredConstructor

public Constructor getDeclaredConstructor(Class[] parameterTypes)
                                   throws NoSuchMethodException,
                                          SecurityException
Returns a Constructor object that reflects the specified constructor of the class or interface represented by this Class object. The parameterTypes parameter is an array of Class objects that identify the constructor's formal parameter types, in declared order. If this Class object represents an inner class declared in a non-static context, the formal parameter types include the explicit enclosing instance as the first parameter.

Parameters:
parameterTypes - the parameter array
Returns:
The Constructor object for the constructor with the specified parameter list
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared constructor
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredConstructors

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

See The Java Language Specification, section 8.2.

Returns:
the array of Constructor objects representing all the declared constructors of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared constructors within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredField

public Field getDeclaredField(String name)
                       throws NoSuchFieldException,
                              SecurityException
Returns a Field object that reflects the specified declared field of the class or interface represented by this Class object. The name parameter is a String that specifies the simple name of the desired field. Note that this method will not reflect the length field of an array class.

Parameters:
name - the name of the field
Returns:
the Field object for the specified field in this class
Throws:
NoSuchFieldException - if a field with the specified name is not found.
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared field
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredFields

public Field[] getDeclaredFields()
                          throws SecurityException
Returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object. This includes public, protected, default (package) access, and private fields, but excludes inherited fields. The elements in the array returned are not sorted and are not in any particular order. This method returns an array of length 0 if the class or interface declares no fields, or if this Class object represents a primitive type, an array class, or void.

See The Java Language Specification, sections 8.2 and 8.3.

Returns:
the array of Field objects representing all the declared fields of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared fields within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredMethod

public Method getDeclaredMethod(String name,
                                Class[] parameterTypes)
                         throws NoSuchMethodException,
                                SecurityException
Returns a Method object that reflects the specified declared method of the class or interface represented by this Class object. The name parameter is a String that specifies the simple name of the desired method, and the parameterTypes parameter is an array of Class objects that identify the method's formal parameter types, in declared order. If more than one method with the same parameter types is declared in a class, and one of these methods has a return type that is more specific than any of the others, that method is returned; otherwise one of the methods is chosen arbitrarily. If the name is "<init>"or "<clinit>" a NoSuchMethodException is raised.

Parameters:
name - the name of the method
parameterTypes - the parameter array
Returns:
the Method object for the method of this class matching the specified name and parameters
Throws:
NoSuchMethodException - if a matching method is not found.
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared method
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaredMethods

public Method[] getDeclaredMethods()
                            throws SecurityException
Returns an array of Method objects reflecting all the methods declared by the class or interface represented by this Class object. This includes public, protected, default (package) access, and private methods, but excludes inherited methods. The elements in the array returned are not sorted and are not in any particular order. This method returns an array of length 0 if the class or interface declares no methods, or if this Class object represents a primitive type, an array class, or void. The class initialization method <clinit> is not included in the returned array. If the class declares multiple public member methods with the same parameter types, they are all included in the returned array.

See The Java Language Specification, section 8.2.

Returns:
the array of Method objects representing all the declared methods of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.DECLARED)} denies access to the declared methods within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getDeclaringClass

public native Class getDeclaringClass()
If the class or interface represented by this Class object is a member of another class, returns the Class object representing the class in which it was declared. This method returns null if this class or interface is not a member of any other class. If this Class object represents an array class, a primitive type, or void,then this method returns null.

Returns:
the declaring class for this class

getEnclosingClass

public Class getEnclosingClass()
Returns the immediately enclosing class of the underlying class. If the underlying class is a top level class this method returns null.

Returns:
the immediately enclosing class of the underlying class

getEnclosingConstructor

public Constructor getEnclosingConstructor()
If this Class object represents a local or anonymous class within a constructor, returns a {@link java.lang.reflect.Constructor Constructor} object representing the immediately enclosing constructor of the underlying class. Returns null otherwise. In particular, this method returns null if the underlying class is a local or anonymous class immediately enclosed by a type declaration, instance initializer or static initializer.

Returns:
the immediately enclosing constructor of the underlying class, if that class is a local or anonymous class; otherwise null.

getEnclosingMethod

public Method getEnclosingMethod()
If this Class object represents a local or anonymous class within a method, returns a {@link java.lang.reflect.Method Method} object representing the immediately enclosing method of the underlying class. Returns null otherwise. In particular, this method returns null if the underlying class is a local or anonymous class immediately enclosed by a type declaration, instance initializer or static initializer.

Returns:
the immediately enclosing method of the underlying class, if that class is a local or anonymous class; otherwise null.

getEnumConstants

public Object[] getEnumConstants()
Returns the elements of this enum class or null if this Class object does not represent an enum type.

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

getField

public Field getField(String name)
               throws NoSuchFieldException,
                      SecurityException
Returns a Field object that reflects the specified public member field of the class or interface represented by this Class object. The name parameter is a String specifying the simple name of the desired field.

The field to be reflected is determined by the algorithm that follows. Let C be the class represented by this object:

  1. If C declares a public field with the name specified, that is the field to be reflected.
  2. If no field was found in step 1 above, this algorithm is applied recursively to each direct superinterface of C. The direct superinterfaces are searched in the order they were declared.
  3. If no field was found in steps 1 and 2 above, and C has a superclass S, then this algorithm is invoked recursively upon S. If C has no superclass, then a NoSuchFieldException is thrown.

See The Java Language Specification, sections 8.2 and 8.3.

Parameters:
name - the field name
Returns:
the Field object of this class specified by name
Throws:
NoSuchFieldException - if a field with the specified name is not found.
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the field
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getFields

public Field[] getFields()
                  throws SecurityException
Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object. The elements in the array returned are not sorted and are not in any particular order. This method returns an array of length 0 if the class or interface has no accessible public fields, or if it represents an array class, a primitive type, or void.

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

The implicit length field for array class is not reflected by this method. User code should use the methods of class Array to manipulate arrays.

See The Java Language Specification, sections 8.2 and 8.3.

Returns:
the array of Field objects representing the public fields
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the fields within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getGenericInterfaces

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

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

If this object represents a class, the return value is an array containing objects representing all interfaces implemented by the class. The order of the interface objects in the array corresponds to the order of the interface names in the implements clause of the declaration of the class represented by this object. In the case of an array class, the interfaces Cloneable and Serializable are returned in that order.

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

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

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

Returns:
an array of interfaces implemented by this class

getGenericSuperclass

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

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

Returns:
the superclass of the class represented by this object

getInterfaces

public native Class[] getInterfaces()
Determines the interfaces implemented by the class or interface represented by this object.

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

 class Shimmer implements FloorWax, DessertTopping { ... }
 
suppose the value of s is an instance of Shimmer; the value of the expression:
 s.getClass().getInterfaces()[0]
 
is the Class object that represents interface FloorWax; and the value of:
 s.getClass().getInterfaces()[1]
 
is the Class object that represents interface DessertTopping.

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

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

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

Returns:
an array of interfaces implemented by this class.

getMethod

public Method getMethod(String name,
                        Class[] parameterTypes)
                 throws NoSuchMethodException,
                        SecurityException
Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object. The name parameter is a String specifying the simple name of the desired method. The parameterTypes parameter is an array of Class objects that identify the method's formal parameter types, in declared order. If parameterTypes is null, it is treated as if it were an empty array.

If the name is "{@code };"or "{@code }" a NoSuchMethodException is raised. Otherwise, the method to be reflected is determined by the algorithm that follows. Let C be the class represented by this object:

  1. C is searched for any matching methods. If no matching method is found, the algorithm of step 1 is invoked recursively on the superclass of C.
  2. If no method was found in step 1 above, the superinterfaces of C are searched for a matching method. If any such method is found, it is reflected.
To find a matching method in a class C:  If C declares exactly one public method with the specified name and exactly the same formal parameter types, that is the method reflected. If more than one such method is found in C, and one of these methods has a return type that is more specific than any of the others, that method is reflected; otherwise one of the methods is chosen arbitrarily.

Note that there may be more than one matching method in a class because while the Java language forbids a class to declare multiple methods with the same signature but different return types, the Java virtual machine does not. This increased flexibility in the virtual machine can be used to implement various language features. For example, covariant returns can be implemented with {@linkplain java.lang.reflect.Method#isBridge bridge methods}; the bridge method and the method being overridden would have the same signature but different return types.

See The Java Language Specification, sections 8.2 and 8.4.

Parameters:
name - the name of the method
parameterTypes - the list of parameters
Returns:
the Method object that matches the specified name and parameterTypes
Throws:
NoSuchMethodException - if a matching method is not found or if the name is "<init>"or "<clinit>".
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the method
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getMethods

public Method[] getMethods()
                    throws SecurityException
Returns an array containing Method objects reflecting all the public member 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. Array classes return all the (public) member methods inherited from the Object class. The elements in the array returned are not sorted and are not in any particular order. This method returns an array of length 0 if this Class object represents a class or interface that has no public member methods, or if this Class object represents a primitive type or void.

The class initialization method <clinit> is not included in the returned array. If the class declares multiple public member methods with the same parameter types, they are all included in the returned array.

See The Java Language Specification, sections 8.2 and 8.4.

Returns:
the array of Method objects representing the public methods of this class
Throws:
SecurityException - If a security manager, s, is present and any of the following conditions is met:
  • invocation of {@link SecurityManager#checkMemberAccess s.checkMemberAccess(this, Member.PUBLIC)} denies access to the methods within this class
  • the caller's class loader is not the same as or an ancestor of the class loader for the current class and invocation of {@link SecurityManager#checkPackageAccess s.checkPackageAccess()} denies access to the package of this class

getModifiers

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

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

The modifier encodings are defined in The Java Virtual Machine Specification, table 4.1.

Returns:
the int representing the modifiers for this class

getName

public String getName()
Returns the name of the entity (class, interface, array class, primitive type, or void) represented by this Class object, as a String.

If this class object represents a reference type that is not an array type then the binary name of the class is returned, as specified by the Java Language Specification, Second Edition.

If this class object represents a primitive type or void, then the name returned is a String equal to the Java language keyword corresponding to the primitive type or void.

If this class object represents a class of arrays, then the internal form of the name consists of the name of the element type preceded by one or more '[' characters representing the depth of the array nesting. The encoding of element type names is as follows:

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

The class or interface name classname is the binary name of the class specified above.

Examples:

 String.class.getName()
     returns "java.lang.String"
 byte.class.getName()
     returns "byte"
 (new Object[3]).getClass().getName()
     returns "[Ljava.lang.Object;"
 (new int[3][4][5][6][7][8][9]).getClass().getName()
     returns "[[[[[[[I"
 

Returns:
the name of the class or interface represented by this object.

getPackage

public Package getPackage()
Gets the package for this class. The class loader of this class is used to find the package. If the class was loaded by the bootstrap class loader the set of packages loaded from CLASSPATH is searched to find the package of the class. Null is returned if no package object was created by the class loader of this class.

Packages have attributes for versions and specifications only if the information was defined in the manifests that accompany the classes, and if the class loader created the package instance with the attributes from the manifest.

Returns:
the package of the class, or null if no package information is available from the archive or codebase.

getProtectionDomain

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

Returns:
the ProtectionDomain of this class

getResource

public URL getResource(String name)
Finds a resource with a given name. The rules for searching resources associated with a given class are implemented by the defining {@linkplain ClassLoader class loader} of the class. This method delegates to this object's class loader. If this object was loaded by the bootstrap class loader, the method delegates to {@link ClassLoader#getSystemResource}.

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

Parameters:
name - name of the desired resource
Returns:
A {@link java.net.URL} object or null if no resource with this name is found

getResourceAsStream

public InputStream getResourceAsStream(String name)
Finds a resource with a given name. The rules for searching resources associated with a given class are implemented by the defining {@linkplain ClassLoader class loader} of the class. This method delegates to this object's class loader. If this object was loaded by the bootstrap class loader, the method delegates to {@link ClassLoader#getSystemResourceAsStream}.

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

Parameters:
name - name of the desired resource
Returns:
A {@link java.io.InputStream} object or null if no resource with this name is found

getSigners

public native 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 this object represents a primitive type or void.

getSimpleName

public String getSimpleName()
Returns the simple name of the underlying class as given in the source code. Returns an empty string if the underlying class is anonymous.

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

Returns:
the simple name of the underlying class

getSuperclass

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

Returns:
the superclass of the class represented by this object.

getTypeParameters

public TypeVariable[] getTypeParameters()
Returns an array of TypeVariable objects that represent the type variables declared by the generic declaration represented by this GenericDeclaration object, in declaration order. Returns an array of length 0 if the underlying generic declaration declares no type variables.

Returns:
an array of TypeVariable objects that represent the type variables declared by this generic declaration

isAnnotation

public boolean isAnnotation()
Returns true if this Class object represents an annotation type. Note that if this method returns true, {@link #isInterface()} would also return true, as all annotation types are also interfaces.

Returns:
true if this class object represents an annotation type; false otherwise

isAnnotationPresent

public boolean isAnnotationPresent(Class annotationClass)
Parameters:
annotationClass

isAnonymousClass

public boolean isAnonymousClass()
Returns true if and only if the underlying class is an anonymous class.

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

isArray

public native boolean isArray()
Determines if this Class object represents an array class.

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

isAssignableFrom

public native boolean isAssignableFrom(Class cls)
Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter. It returns true if so; otherwise it returns false. If this Class object represents a primitive type, this method returns true if the specified Class parameter is exactly this Class object; otherwise it returns false.

Specifically, this method tests whether the type represented by the specified Class parameter can be converted to the type represented by this Class object via an identity conversion or via a widening reference conversion. See The Java Language Specification, sections 5.1.1 and 5.1.4 , for details.

Parameters:
cls - the Class object to be checked
Returns:
the boolean value indicating whether objects of the type cls can be assigned to objects of this class

isEnum

public boolean isEnum()
Returns true if and only if this class was declared as an enum in the source code.

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

isInstance

public native boolean isInstance(Object obj)
Determines if the specified Object is assignment-compatible with the object represented by this Class. This method is the dynamic equivalent of the Java language instanceof operator. The method returns true if the specified Object argument is non-null and can be cast to the reference type represented by this Class object without raising a ClassCastException. It returns false otherwise.

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

Parameters:
obj - the object to check
Returns:
true if obj is an instance of this class

isInterface

public native boolean isInterface()
Determines if the specified Class object represents an interface type.

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

isLocalClass

public boolean isLocalClass()
Returns true if and only if the underlying class is a local class.

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

isMemberClass

public boolean isMemberClass()
Returns true if and only if the underlying class is a member class.

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

isPrimitive

public native boolean isPrimitive()
Determines if the specified Class object represents a primitive type.

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

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

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

isSynthetic

public boolean isSynthetic()
Returns true if this class is a synthetic class; returns false otherwise.

Returns:
true if and only if this class is a synthetic class as defined by the Java Language Specification.

newInstance

public Object newInstance()
                   throws InstantiationException,
                          IllegalAccessException
Creates a new instance of the class represented by this Class object. The class is instantiated as if by a new expression with an empty argument list. The class is initialized if it has not already been initialized.

Note that this method propagates any exception thrown by the nullary constructor, including a checked exception. Use of this method effectively bypasses the compile-time exception checking that would otherwise be performed by the compiler. The {@link java.lang.reflect.Constructor#newInstance(java.lang.Object...) Constructor.newInstance} method avoids this problem by wrapping any exception thrown by the constructor in a (checked) {@link java.lang.reflect.InvocationTargetException}.

Returns:
a newly allocated instance of the class represented by this object.
Throws:
InstantiationException - if this Class represents an abstract class, an interface, an array class, a primitive type, or void; or if the class has no nullary constructor; or if the instantiation fails for some other reason.
IllegalAccessException - if the class or its nullary constructor is not accessible.

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 fully qualified name of the class in the format returned by getName. If this Class object represents a primitive type, this method returns the name of the primitive type. If this Class object represents void this method returns "void".

Overrides:
toString in class Object
Returns:
a string representation of this class object.


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The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.