java.lang
Class Class

java.lang.Object
  java.lang.Class

All Implemented Interfaces:

Serializable

public final class Class

extends Object

implements Serializable

Instances of the class Class represent classes and interfaces in a running Java application. 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());
 

Since:

JDK1.0

Author:

unascribed

See Also:

ClassLoader.defineClass(byte[], int, int), Serialized Form

Nested Class Summary

(package private) static class

Class.MethodArray

Field Summary

private static java.security.ProtectionDomain	allPermDomain protection domain returned when the internal domain is null
private Constructor	cachedConstructor
private SoftReference	declaredConstructors
private SoftReference	declaredFields
private SoftReference	declaredMethods
private SoftReference	declaredPublicFields
private SoftReference	declaredPublicMethods
private static boolean	initted
private Class	newInstanceCallerCache
private SoftReference	publicConstructors
private SoftReference	publicFields
private SoftReference	publicMethods
private static sun.reflect.ReflectionFactory	reflectionFactory
private static ObjectStreamField[]	serialPersistentFields Class Class is special cased within the Serialization Stream Protocol.
private static long	serialVersionUID use serialVersionUID from JDK 1.1 for interoperability
private static boolean	useCaches Reflection support.

Constructor Summary

private

Class()

Method Summary

private static void	addAll(Collection c, Field[] o)
private static String	argumentTypesToString(Class[] argTypes)
private static boolean	arrayContentsEq(Object[] a1, Object[] a2)
private static void	checkInitted()
private void	checkMemberAccess(int which, ClassLoader ccl)
private static Constructor[]	copyConstructors(Constructor[] arg)
private static Field[]	copyFields(Field[] arg)
private static Method[]	copyMethods(Method[] arg)
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.
private static boolean	desiredAssertionStatus0(Class clazz)
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.
private static Class	forName0(String name, boolean initialize, ClassLoader loader) Called after security checks have been made.
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.
ClassLoader	getClassLoader() Returns the class loader for the class.
(package private) ClassLoader	getClassLoader0()
Class	getComponentType() 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.
private Constructor	getConstructor0(Class[] parameterTypes, int which)
Constructor[]	getConstructors() Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object.
Class[]	getDeclaredClasses() Returns an array of Class objects reflecting all the classes and interfaces declared as members of the class represented by this Class object.
private Class[]	getDeclaredClasses0()
Constructor	getDeclaredConstructor(Class[] parameterTypes) Returns a Constructor object that reflects the specified constructor of the class or interface represented by this Class object.
Constructor[]	getDeclaredConstructors() Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.
private Constructor[]	getDeclaredConstructors0(boolean publicOnly)
Field	getDeclaredField(String name) Returns a Field object that reflects the specified declared field of the class or interface represented by this Class object.
Field[]	getDeclaredFields() Returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object.
private Field[]	getDeclaredFields0(boolean publicOnly)
Method	getDeclaredMethod(String name, Class[] parameterTypes) Returns a Method object that reflects the specified declared method of the class or interface represented by this Class object.
Method[]	getDeclaredMethods() Returns an array of Method objects reflecting all the methods declared by the class or interface represented by this Class object.
private Method[]	getDeclaredMethods0(boolean publicOnly)
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.
Field	getField(String name) Returns a Field object that reflects the specified public member field of the class or interface represented by this Class object.
private Field	getField0(String name)
Field[]	getFields() Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object.
Class[]	getInterfaces() 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.
private Method	getMethod0(String name, Class[] parameterTypes)
Method[]	getMethods() 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 and those inherited from superclasses and superinterfaces.
int	getModifiers() Returns the Java language modifiers for this class or interface, encoded in an integer.
String	getName() Returns the name of the entity (class, interface, array class, primitive type, or void) represented by this Class object, as a String.
Package	getPackage() Gets the package for this class.
(package private) static Class	getPrimitiveClass(String name)
java.security.ProtectionDomain	getProtectionDomain() Returns the ProtectionDomain of this class.
private java.security.ProtectionDomain	getProtectionDomain0() Returns the ProtectionDomain of this class.
private static sun.reflect.ReflectionFactory	getReflectionFactory()
URL	getResource(String name) Finds a resource with a given name.
InputStream	getResourceAsStream(String name) Finds a resource with a given name.
Object[]	getSigners() Gets the signers of this class.
Class	getSuperclass() Returns the Class representing the superclass of the entity (class, interface, primitive type or void) represented by this Class.
boolean	isArray() Determines if this Class object represents an array class.
boolean	isAssignableFrom(Class cls) Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter.
boolean	isInstance(Object obj) Determines if the specified Object is assignment-compatible with the object represented by this Class.
boolean	isInterface() Determines if the specified Class object represents an interface type.
boolean	isPrimitive() Determines if the specified Class object represents a primitive type.
Object	newInstance() Creates a new instance of the class represented by this Class object.
private Object	newInstance0()
private Constructor[]	privateGetDeclaredConstructors(boolean publicOnly)
private Field[]	privateGetDeclaredFields(boolean publicOnly)
private Method[]	privateGetDeclaredMethods(boolean publicOnly)
private Field[]	privateGetPublicFields(Set traversedInterfaces)
private Method[]	privateGetPublicMethods()
private static void	registerNatives()
private String	resolveName(String name) Add a package name prefix if the name is not absolute Remove leading "/" if name is absolute
private Field	searchFields(Field[] fields, String name)
private static Method	searchMethods(Method[] methods, String name, Class[] parameterTypes)
(package private) void	setProtectionDomain0(java.security.ProtectionDomain pd) Set the ProtectionDomain for this class.
(package private) void	setSigners(Object[] signers) Set the signers of this class.
String	toString() Converts the object to a string.

Methods inherited from class java.lang.Object

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

Field Detail

cachedConstructor

private transient volatile Constructor cachedConstructor

newInstanceCallerCache

private transient volatile Class newInstanceCallerCache

allPermDomain

private static java.security.ProtectionDomain allPermDomain

protection domain returned when the internal domain is null

useCaches

private static boolean useCaches

Reflection support.

declaredFields

private transient volatile SoftReference declaredFields

publicFields

private transient volatile SoftReference publicFields

declaredMethods

private transient volatile SoftReference declaredMethods

publicMethods

private transient volatile SoftReference publicMethods

declaredConstructors

private transient volatile SoftReference declaredConstructors

publicConstructors

private transient volatile SoftReference publicConstructors

declaredPublicFields

private transient volatile SoftReference declaredPublicFields

declaredPublicMethods

private transient volatile SoftReference declaredPublicMethods

serialVersionUID

private static final long serialVersionUID

use serialVersionUID from JDK 1.1 for interoperability

See Also:

Constant Field Values

serialPersistentFields

private static final ObjectStreamField[] serialPersistentFields

Class Class is special cased within the Serialization Stream Protocol. A Class instance is written intially into an ObjectOutputStream in the following format:

      TC_CLASS ClassDescriptor
      A ClassDescriptor is a special cased serialization of 
      a java.io.ObjectStreamClass instance. 
 

A new handle is generated for the initial time the class descriptor is written into the stream. Future references to the class descriptor are written as references to the initial class descriptor instance.

See Also:

ObjectStreamClass

reflectionFactory

private static sun.reflect.ReflectionFactory reflectionFactory

initted

private static boolean initted

Constructor Detail

Class

private Class()

Method Detail

registerNatives

private static void registerNatives()

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.

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:

LinkageError - if the linkage fails

ExceptionInInitializerError - if the initialization provoked by this method fails

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:

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

Since:

1.2

See Also:

forName(String), ClassLoader

forName0

private static Class forName0(String name,
                              boolean initialize,
                              ClassLoader loader)
                       throws ClassNotFoundException

Called after security checks have been made.

Throws:

ClassNotFoundException

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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 this Class represents an abstract class, an interface, an array class, a primitive type, or void; or if the class has no nullary constructor; or if the instantiation fails for some other reason.

ExceptionInInitializerError - if the initialization provoked by this method fails.

SecurityException - if there is no permission to create a new instance.

newInstance0

private Object newInstance0()
                     throws InstantiationException,
                            IllegalAccessException

Throws:

InstantiationException

IllegalAccessException

isInstance

public boolean isInstance(Object obj)

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

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

Parameters:

obj - the object to check

Returns:

true if obj is an instance of this class

Since:

JDK1.1

isAssignableFrom

public boolean isAssignableFrom(Class cls)

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

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

Throws:

NullPointerException - if the specified Class parameter is null.

Since:

JDK1.1

isInterface

public boolean isInterface()

Determines if the specified Class object represents an interface type.

Returns:

true if this object represents an interface; false otherwise.

isArray

public boolean isArray()

Determines if this Class object represents an array class.

Returns:

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

Since:

JDK1.1

isPrimitive

public boolean isPrimitive()

Determines if the specified Class object represents a primitive type.

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

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

Returns:

true if and only if this class represents a primitive type

Since:

JDK1.1

See Also:

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

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.

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.

Throws:

SecurityException - if a security manager exists and its checkPermission method denies access to the class loader for the class.

See Also:

ClassLoader, SecurityManager.checkPermission(java.security.Permission), RuntimePermission

getClassLoader0

ClassLoader getClassLoader0()

getSuperclass

public 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.

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.

getInterfaces

public 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.

getComponentType

public Class getComponentType()

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

Returns:

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

Since:

JDK1.1

See Also:

Array

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 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

Since:

JDK1.1

See Also:

Modifier

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 this object represents a primitive type or void.

Since:

JDK1.1

setSigners

void setSigners(Object[] signers)

Set the signers of this class.

getDeclaringClass

public Class getDeclaringClass()

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

Returns:

the declaring class for this class

Since:

JDK1.1

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.

For this class and each of its superclasses, the following security checks are performed: If there is a security manager, the security manager's checkMemberAccess method is called with this and Member.PUBLIC as its arguments, where this is this class or the superclass whose members are being determined. If the class is in a package, then the security manager's checkPackageAccess method is also called with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

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

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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 access to the information is denied.

Since:

JDK1.1

See Also:

Field, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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 and those inherited from superclasses and superinterfaces. 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 an array class, primitive type, or void.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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 access to the information is denied.

Since:

JDK1.1

See Also:

Method, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

the array containing Method objects for all the declared public constructors of this class matches the specified parameterTypes

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Constructor, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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.

NullPointerException - if name is null

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Field, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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 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 there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

If the name is "<init>"or "<clinit>" 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.

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>".

NullPointerException - if name is null

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Method, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.PUBLIC as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Parameters:

parameterTypes - the parameter array

Returns:

the Method object of the public constructor that matches the specified parameterTypes

Throws:

NoSuchMethodException - if a matching method is not found.

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Constructor, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

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

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

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

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Field, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

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

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Method, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Returns:

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

Throws:

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Constructor, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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.

NullPointerException - if name is null

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Field, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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.

If there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

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.

NullPointerException - if name is null

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Method, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

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 there is a security manager, this method first calls the security manager's checkMemberAccess method with this and Member.DECLARED as its arguments. If the class is in a package, then this method also calls the security manager's checkPackageAccess method with the package name as its argument. Either of these calls could result in a SecurityException.

Parameters:

parameterTypes - the parameter array

Returns:

The Method object for the constructor with the specified parameter list

Throws:

NoSuchMethodException - if a matching method is not found.

SecurityException - if access to the information is denied.

Since:

JDK1.1

See Also:

Constructor, SecurityManager.checkMemberAccess(Class, int), SecurityManager.checkPackageAccess(String)

getResourceAsStream

public InputStream getResourceAsStream(String name)

Finds a resource with a given name. This method returns null if no resource with this name is found. The rules for searching resources associated with a given class are implemented by the defining class loader of the class.

This method delegates the call to its class loader, after making these changes to the resource name: if the resource name starts with "/", it is unchanged; otherwise, the package name is prepended to the resource name after converting "." to "/". If this object was loaded by the bootstrap loader, the call is delegated to ClassLoader.getSystemResourceAsStream.

Parameters:

name - name of the desired resource

Returns:

a java.io.InputStream object.

Throws:

NullPointerException - if name is null.

Since:

JDK1.1

See Also:

ClassLoader

getResource

public URL getResource(String name)

Finds a resource with a given name. This method returns null if no resource with this name is found. The rules for searching resources associated with a given class are implemented by the * defining class loader of the class.

This method delegates the call to its class loader, after making these changes to the resource name: if the resource name starts with "/", it is unchanged; otherwise, the package name is prepended to the resource name after converting "." to "/". If this object was loaded by the bootstrap loader, the call is delegated to ClassLoader.getSystemResource.

Parameters:

name - name of the desired resource

Returns:

a java.net.URL object.

Since:

JDK1.1

See Also:

ClassLoader

getProtectionDomain

public java.security.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

Throws:

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

Since:

1.2

See Also:

ProtectionDomain, SecurityManager.checkPermission(java.security.Permission), RuntimePermission

getProtectionDomain0

private java.security.ProtectionDomain getProtectionDomain0()

Returns the ProtectionDomain of this class.

setProtectionDomain0

void setProtectionDomain0(java.security.ProtectionDomain pd)

Set the ProtectionDomain for this class. Called by ClassLoader.defineClass.

getPrimitiveClass

static Class getPrimitiveClass(String name)

checkMemberAccess

private void checkMemberAccess(int which,
                               ClassLoader ccl)

resolveName

private String resolveName(String name)

Add a package name prefix if the name is not absolute Remove leading "/" if name is absolute

privateGetDeclaredFields

private Field[] privateGetDeclaredFields(boolean publicOnly)

privateGetPublicFields

private Field[] privateGetPublicFields(Set traversedInterfaces)

addAll

private static void addAll(Collection c,
                           Field[] o)

privateGetDeclaredConstructors

private Constructor[] privateGetDeclaredConstructors(boolean publicOnly)

privateGetDeclaredMethods

private Method[] privateGetDeclaredMethods(boolean publicOnly)

privateGetPublicMethods

private Method[] privateGetPublicMethods()

searchFields

private Field searchFields(Field[] fields,
                           String name)

getField0

private Field getField0(String name)
                 throws NoSuchFieldException

Throws:

NoSuchFieldException

searchMethods

private static Method searchMethods(Method[] methods,
                                    String name,
                                    Class[] parameterTypes)

getMethod0

private Method getMethod0(String name,
                          Class[] parameterTypes)

getConstructor0

private Constructor getConstructor0(Class[] parameterTypes,
                                    int which)
                             throws NoSuchMethodException

Throws:

NoSuchMethodException

arrayContentsEq

private static boolean arrayContentsEq(Object[] a1,
                                       Object[] a2)

copyFields

private static Field[] copyFields(Field[] arg)

copyMethods

private static Method[] copyMethods(Method[] arg)

copyConstructors

private static Constructor[] copyConstructors(Constructor[] arg)

getDeclaredFields0

private Field[] getDeclaredFields0(boolean publicOnly)

getDeclaredMethods0

private Method[] getDeclaredMethods0(boolean publicOnly)

getDeclaredConstructors0

private Constructor[] getDeclaredConstructors0(boolean publicOnly)

getDeclaredClasses0

private Class[] getDeclaredClasses0()

argumentTypesToString

private static String argumentTypesToString(Class[] argTypes)

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.

Since:

1.4

See Also:

ClassLoader.setClassAssertionStatus(java.lang.String, boolean), ClassLoader.setPackageAssertionStatus(java.lang.String, boolean), ClassLoader.setDefaultAssertionStatus(boolean)

desiredAssertionStatus0

private static boolean desiredAssertionStatus0(Class clazz)

getReflectionFactory

private static sun.reflect.ReflectionFactory getReflectionFactory()

checkInitted

private static void checkInitted()