Class Class<T>

public Method _getMethod(String methodName,
                         Class<T>[] args)

public T cast(Object obj)

Returns the specified object, cast to this Class' type.

Parameters:

obj - the object to cast

Throws:

ClassCastException - if obj is not an instance of this class

Since:

1.5

public boolean desiredAssertionStatus()

Returns the desired assertion status of this class, if it were to be initialized at this moment. The class assertion status, if set, is returned; the backup is the default package status; then if there is a class loader, that default is returned; and finally the system default is returned. This method seldom needs calling in user code, but exists for compilers to implement the assert statement. Note that there is no guarantee that the result of this method matches the class's actual assertion status.

Returns:

the desired assertion status

Since:

1.4

See Also:

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

public extends Annotation> A getAnnotation(Class annotationClass)

Returns this class' annotation for the specified annotation type, or null if no such annotation exists.

Parameters:

annotationClass - the type of annotation to look for.

Returns:

this class' annotation for the specified type, or null if no such annotation exists.

Since:

1.5

protected void finalize()
            throws Throwable

Called on an object by the Virtual Machine at most once, at some point after the Object is determined unreachable but before it is destroyed. You would think that this means it eventually is called on every Object, but this is not necessarily the case. If execution terminates abnormally, garbage collection does not always happen. Thus you cannot rely on this method to always work. For finer control over garbage collection, use references from the java.lang.ref package.

Virtual Machines are free to not call this method if they can determine that it does nothing important; for example, if your class extends Object and overrides finalize to do simply super.finalize().

finalize() will be called by a Thread that has no locks on any Objects, and may be called concurrently. There are no guarantees on the order in which multiple objects are finalized. This means that finalize() is usually unsuited for performing actions that must be thread-safe, and that your implementation must be use defensive programming if it is to always work.

If an Exception is thrown from finalize() during garbage collection, it will be patently ignored and the Object will still be destroyed.

It is allowed, although not typical, for user code to call finalize() directly. User invocation does not affect whether automatic invocation will occur. It is also permitted, although not recommended, for a finalize() method to "revive" an object by making it reachable from normal code again.

Unlike constructors, finalize() does not get called for an object's superclass unless the implementation specifically calls super.finalize().

The default implementation does nothing.

Overrides:

finalize in interface Object

Throws:

Throwable - permits a subclass to throw anything in an overridden version; but the default throws nothing

See Also:

System.gc(), System.runFinalizersOnExit(boolean), java.lang.ref

public static Class forName(String className)
            throws ClassNotFoundException

Use the classloader of the current class to load, link, and initialize a class. This is equivalent to your code calling Class.forName(name, true, getClass().getClassLoader()).

Parameters:

Returns:

the Class object representing the class

Throws:

ClassNotFoundException - if the class was not found by the classloader

public static Class forName(String className,
                               boolean initialize,
                               ClassLoader loader)
            throws ClassNotFoundException

Use the specified classloader to load and link a class. If the loader is null, this uses the bootstrap class loader (provide the security check succeeds). Unfortunately, this method cannot be used to obtain the Class objects for primitive types or for void, you have to use the fields in the appropriate java.lang wrapper classes.

Calls classloader.loadclass(name, initialize).

Parameters:

initialize - whether or not to initialize the class at this time

Throws:

ClassNotFoundException - if the class was not found by the classloader

SecurityException - if the classloader argument is null and the caller does not have the RuntimePermission("getClassLoader") permission

Since:

1.2

See Also:

ClassLoader

public Annotation[] getAnnotations()

Returns all annotations associated with this class. If there are no annotations associated with this class, then a zero-length array will be returned. The returned array may be modified by the client code, but this will have no effect on the annotation content of this class, and hence no effect on the return value of this method for future callers.

Specified by:

getAnnotations in interface AnnotatedElement

Returns:

this class' annotations.

Since:

1.5

public String getCanonicalName()

Returns the canonical name of this class, as defined by section 6.7 of the Java language specification. Each package, top-level class, top-level interface and primitive type has a canonical name. A member class has a canonical name, if its parent class has one. Likewise, an array type has a canonical name, if its component type does. Local or anonymous classes do not have canonical names.

The canonical name for top-level classes, top-level interfaces and primitive types is always the same as the fully-qualified name. For array types, the canonical name is the canonical name of its component type with `[]' appended.

The canonical name of a member class always refers to the place where the class was defined, and is composed of the canonical name of the defining class and the simple name of the member class, joined by `.'. For example, if a Person class has an inner class, M, then both its fully-qualified name and canonical name is Person.M. A subclass, Staff, of Person refers to the same inner class by the fully-qualified name of Staff.M, but its canonical name is still Person.M.

Where no canonical name is present, null is returned.

Returns:

the canonical name of the class, or null if the class doesn't have a canonical name.

Since:

1.5

public ClassLoader getClassLoader()

Get the ClassLoader that loaded this class. If the class was loaded by the bootstrap classloader, this method will return null. If there is a security manager, and the caller's class loader is not an ancestor of the requested one, a security check of RuntimePermission("getClassLoader") must first succeed. Primitive types and void return null.

Returns:

the ClassLoader that loaded this class

Throws:

SecurityException - if the security check fails

See Also:

ClassLoader, RuntimePermission

public Class[] getClasses()

Get all the public member classes and interfaces declared in this class or inherited from superclasses. This returns an array of length 0 if there are no member classes, including for primitive types. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Returns:

all public member classes in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Class getComponentType()

If this is an array, get the Class representing the type of array. Examples: "[[Ljava.lang.String;" would return "[Ljava.lang.String;", and calling getComponentType on that would give "java.lang.String". If this is not an array, returns null.

Returns:

the array type of this class, or null

Since:

1.1

See Also:

Array

public Constructor getConstructor(Class... args)
            throws NoSuchMethodException

Get a public constructor declared in this class. If the constructor takes no argument, an array of zero elements and null are equivalent for the types argument. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Parameters:

Returns:

the constructor

Throws:

NoSuchMethodException - if the constructor does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getConstructors()

public Constructor[] getConstructors()

Get all the public constructors of this class. This returns an array of length 0 if there are no constructors, including for primitive types, arrays, and interfaces. It does, however, include the default constructor if one was supplied by the compiler. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Returns:

all public constructors in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Annotation[] getDeclaredAnnotations()

Returns all annotations directly defined by this class. If there are no annotations associated with this class, then a zero-length array will be returned. The returned array may be modified by the client code, but this will have no effect on the annotation content of this class, and hence no effect on the return value of this method for future callers.

Specified by:

getDeclaredAnnotations in interface AnnotatedElement

Returns:

the annotations directly defined by this class.

Since:

1.5

public Class[] getDeclaredClasses()

Get all the declared member classes and interfaces in this class, but not those inherited from superclasses. This returns an array of length 0 if there are no member classes, including for primitive types. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Returns:

all declared member classes in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Constructor getDeclaredConstructor(Class... args)
            throws NoSuchMethodException

Get a constructor declared in this class. If the constructor takes no argument, an array of zero elements and null are equivalent for the types argument. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Parameters:

Returns:

the constructor

Throws:

NoSuchMethodException - if the constructor does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getDeclaredConstructors()

public Constructor[] getDeclaredConstructors()

Get all the declared constructors of this class. This returns an array of length 0 if there are no constructors, including for primitive types, arrays, and interfaces. It does, however, include the default constructor if one was supplied by the compiler. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Returns:

all constructors in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Field getDeclaredField(String fieldName)
            throws NoSuchFieldException

Get a field declared in this class, where name is its simple name. The implicit length field of arrays is not available. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Parameters:

Returns:

the field

Throws:

NoSuchFieldException - if the field does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getDeclaredFields()

public Field[] getDeclaredFields()

Get all the declared fields in this class, but not those inherited from superclasses. This returns an array of length 0 if there are no fields, including for primitive types. This does not return the implicit length field of arrays. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Returns:

all declared fields in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Method getDeclaredMethod(String methodName,
                                Class... args)
            throws NoSuchMethodException

Get a method declared in this class, where name is its simple name. The implicit methods of Object are not available from arrays or interfaces. Constructors (named "<init>" in the class file) and class initializers (name "<clinit>") are not available. The Virtual Machine allows multiple methods with the same signature but differing return types; in such a case the most specific return types are favored, then the final choice is arbitrary. If the method takes no argument, an array of zero elements and null are equivalent for the types argument. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Parameters:

methodName - the name of the method

Returns:

the method

Throws:

NoSuchMethodException - if the method does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getDeclaredMethods()

public Method[] getDeclaredMethods()

Get all the declared methods in this class, but not those inherited from superclasses. This returns an array of length 0 if there are no methods, including for primitive types. This does include the implicit methods of arrays and interfaces which mirror methods of Object, nor does it include constructors or the class initialization methods. The Virtual Machine allows multiple methods with the same signature but differing return types; all such methods are in the returned array. A security check may be performed, with checkMemberAccess(this, Member.DECLARED) as well as checkPackageAccess both having to succeed.

Returns:

all declared methods in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Class getDeclaringClass()

If this is a nested or inner class, return the class that declared it. If not, return null.

Returns:

the declaring class of this class

Since:

1.1

public Class getEnclosingClass()

Returns the class which immediately encloses this class. If this class is a top-level class, this method returns null.

Returns:

the immediate enclosing class, or null if this is a top-level class.

Since:

1.5

public Constructor getEnclosingConstructor()

Returns the constructor which immediately encloses this class. If this class is a top-level class, or a local or anonymous class immediately enclosed by a type definition, instance initializer or static initializer, then null is returned.

Returns:

the immediate enclosing constructor if this class is declared within a constructor. Otherwise, null is returned.

Since:

1.5

public Method getEnclosingMethod()

Returns the method which immediately encloses this class. If this class is a top-level class, or a local or anonymous class immediately enclosed by a type definition, instance initializer or static initializer, then null is returned.

Returns:

the immediate enclosing method if this class is declared within a method. Otherwise, null is returned.

Since:

1.5

public T[] getEnumConstants()

Returns the enumeration constants of this class, or null if this class is not an Enum.

Returns:

an array of Enum constants associated with this class, or null if this class is not an enum.

Since:

1.5

public Field getField(String fieldName)
            throws NoSuchFieldException

Get a public field declared or inherited in this class, where name is its simple name. If the class contains multiple accessible fields by that name, an arbitrary one is returned. The implicit length field of arrays is not available. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Parameters:

fieldName - the name of the field

Returns:

the field

Throws:

NoSuchFieldException - if the field does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getFields()

public Field[] getFields()

Get all the public fields declared in this class or inherited from superclasses. This returns an array of length 0 if there are no fields, including for primitive types. This does not return the implicit length field of arrays. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Returns:

all public fields in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public Type[] getGenericInterfaces()

Returns an array of Type objects which represent the interfaces directly implemented by this class or extended by this interface.

If one of the superinterfaces is a parameterized type, then the object returned for this interface reflects the actual type parameters used in the source code. Type parameters are created using the semantics specified by the ParameterizedType interface, and only if an instance has not already been created.

The order of the interfaces in the array matches the order in which the interfaces are declared. For classes which represent an array, an array of two interfaces, Cloneable and Serializable, is always returned, with the objects in that order. A class representing a primitive type or void always returns an array of zero size.

Returns:

an array of interfaces implemented or extended by this class.

Throws:

TypeNotPresentException - if any of the superinterfaces refers to a non-existant type.

Since:

1.5

See Also:

ParameterizedType

public Type getGenericSuperclass()

Returns a Type object representing the direct superclass, whether class, interface, primitive type or void, of this class. If this class is an array class, then a class instance representing the Object class is returned. If this class is primitive, an interface, or a representation of either the Object class or void, then null is returned.

If the superclass is a parameterized type, then the object returned for this interface reflects the actual type parameters used in the source code. Type parameters are created using the semantics specified by the ParameterizedType interface, and only if an instance has not already been created.

Returns:

the superclass of this class.

Throws:

TypeNotPresentException - if the superclass refers to a non-existant type.

Since:

1.5

See Also:

ParameterizedType

public Class[] getInterfaces()

Get the interfaces this class directly implements, in the order that they were declared. This returns an empty array, not null, for Object, primitives, void, and classes or interfaces with no direct superinterface. Array types return Cloneable and Serializable.

Returns:

the interfaces this class directly implements

public Method getMethod(String methodName,
                        Class... args)
            throws NoSuchMethodException

Get a public method declared or inherited in this class, where name is its simple name. The implicit methods of Object are not available from interfaces. Constructors (named "<init>" in the class file) and class initializers (name "<clinit>") are not available. The Virtual Machine allows multiple methods with the same signature but differing return types, and the class can inherit multiple methods of the same return type; in such a case the most specific return types are favored, then the final choice is arbitrary. If the method takes no argument, an array of zero elements and null are equivalent for the types argument. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Parameters:

methodName - the name of the method

Returns:

the method

Throws:

NoSuchMethodException - if the method does not exist

SecurityException - if the security check fails

Since:

1.1

See Also:

getMethods()

public Method[] getMethods()

Get all the public methods declared in this class or inherited from superclasses. This returns an array of length 0 if there are no methods, including for primitive types. This does not include the implicit methods of interfaces which mirror methods of Object, nor does it include constructors or the class initialization methods. The Virtual Machine allows multiple methods with the same signature but differing return types; all such methods are in the returned array. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Returns:

all public methods in this class

Throws:

SecurityException - if the security check fails

Since:

1.1

public int getModifiers()

Get the modifiers of this class. These can be decoded using Modifier, and is limited to one of public, protected, or private, and any of final, static, abstract, or interface. An array class has the same public, protected, or private modifier as its component type, and is marked final but not an interface. Primitive types and void are marked public and final, but not an interface.

Returns:

the modifiers of this class

Since:

1.1

See Also:

Modifer

public String getName()

Get the name of this class, separated by dots for package separators. If the class represents a primitive type, or void, then the name of the type as it appears in the Java programming language is returned. For instance, Byte.TYPE.getName() returns "byte". Arrays are specially encoded as shown on this table.

 array type          [element type
                     (note that the element type is encoded per
                      this table)
 boolean             Z
 byte                B
 char                C
 short               S
 int                 I
 long                J
 float               F
 double              D
 void                V
 class or interface, alone: <dotted name>
 class or interface, as element type: L<dotted name>;
 

Returns:

the name of this class

public Package getPackage()

Returns the Package in which this class is defined Returns null when this information is not available from the classloader of this class.

Returns:

the package for this class, if it is available

Since:

1.2

public ProtectionDomain getProtectionDomain()

Returns the protection domain of this class. If the classloader did not record the protection domain when creating this class the unknown protection domain is returned which has a null code source and all permissions. A security check may be performed, with RuntimePermission("getProtectionDomain").

Returns:

the protection domain

Throws:

SecurityException - if the security manager exists and the caller does not have RuntimePermission("getProtectionDomain").

Since:

1.2

See Also:

RuntimePermission

public URL getResource(String resourceName)

Get a resource URL using this class's package using the getClassLoader().getResource() method. If this class was loaded using the system classloader, ClassLoader.getSystemResource() is used instead.

If the name you supply is absolute (it starts with a /), then the leading / is removed and it is passed on to getResource(). If it is relative, the package name is prepended, and .'s are replaced with /.

The URL returned is system- and classloader-dependent, and could change across implementations.

Parameters:

resourceName - the name of the resource, generally a path

Returns:

the URL to the resource

Throws:

NullPointerException - if name is null

Since:

1.1

public InputStream getResourceAsStream(String resourceName)

Get a resource using this class's package using the getClassLoader().getResourceAsStream() method. If this class was loaded using the system classloader, ClassLoader.getSystemResource() is used instead.

If the name you supply is absolute (it starts with a /), then the leading / is removed and it is passed on to getResource(). If it is relative, the package name is prepended, and .'s are replaced with /.

The URL returned is system- and classloader-dependent, and could change across implementations.

Parameters:

resourceName - the name of the resource, generally a path

Returns:

an InputStream with the contents of the resource in it, or null

Throws:

NullPointerException - if name is null

Since:

1.1

public Object[] getSigners()

Get the signers of this class. This returns null if there are no signers, such as for primitive types or void.

Returns:

the signers of this class

Since:

1.1

public String getSimpleName()

Returns the simple name for this class, as used in the source code. For normal classes, this is the content returned by getName() which follows the last ".". Anonymous classes have no name, and so the result of calling this method is "". The simple name of an array consists of the simple name of its component type, followed by "[]". Thus, an array with the component type of an anonymous class has a simple name of simply "[]".

Returns:

the simple name for this class.

Since:

1.5

public TypeVariable>[] getTypeParameters()

Returns an array of TypeVariable objects that represents the type variables declared by this class, in declaration order. An array of size zero is returned if this class has no type variables.

Specified by:

getTypeParameters in interface GenericDeclaration

Returns:

the type variables associated with this class.

Since:

1.5

public boolean isAnnotation()

Returns true if this class is an Annotation.

Returns:

true if this is an annotation class.

Since:

1.5

public boolean isAnnotationPresent(Annotation> annotationClass)

Returns true if an annotation for the specified type is associated with this class. This is primarily a short-hand for using marker annotations.

Specified by:

isAnnotationPresent in interface AnnotatedElement

Parameters:

annotationClass - the type of annotation to look for.

Returns:

true if an annotation exists for the specified type.

Since:

1.5

public boolean isAnonymousClass()

Returns true if this object represents an anonymous class.

Returns:

true if this object represents an anonymous class.

Since:

1.5

public boolean isArray()

Return whether this class is an array type.

Returns:

whether this class is an array type

Since:

1.1

public boolean isAssignableFrom(Class c)

Discover whether an instance of the Class parameter would be an instance of this Class as well. Think of doing isInstance(c.newInstance()) or even c.newInstance() instanceof (this class). While this checks widening conversions for objects, it must be exact for primitive types.

Parameters:

c - the class to check

Returns:

whether an instance of c would be an instance of this class as well

Throws:

NullPointerException - if c is null

Since:

1.1

public boolean isEnum()

Returns true if this class is an Enum.

Returns:

true if this is an enumeration class.

Since:

1.5

public boolean isInstance(Object o)

Discover whether an Object is an instance of this Class. Think of it as almost like o instanceof (this class).

Parameters:

o - the Object to check

Returns:

whether o is an instance of this class

Since:

1.1

public boolean isInterface()

Check whether this class is an interface or not. Array types are not interfaces.

Returns:

whether this class is an interface or not

public boolean isLocalClass()

Returns true if this object represents an local class.

Returns:

true if this object represents an local class.

Since:

1.5

public boolean isMemberClass()

Returns true if this object represents an member class.

Returns:

true if this object represents an member class.

Since:

1.5

public boolean isPrimitive()

Return whether this class is a primitive type. A primitive type class is a class representing a kind of "placeholder" for the various primitive types, or void. You can access the various primitive type classes through java.lang.Boolean.TYPE, java.lang.Integer.TYPE, etc., or through boolean.class, int.class, etc.

Returns:

whether this class is a primitive type

Since:

1.1

See Also:

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

public boolean isSynthetic()

Returns true if this class is a synthetic class, generated by the compiler.

Returns:

true if this is a synthetic class.

Since:

1.5

public T newInstance()
            throws InstantiationException,
                   IllegalAccessException

Get a new instance of this class by calling the no-argument constructor. The class is initialized if it has not been already. A security check may be performed, with checkMemberAccess(this, Member.PUBLIC) as well as checkPackageAccess both having to succeed.

Returns:

a new instance of this class

Throws:

InstantiationException - if there is not a no-arg constructor for this class, including interfaces, abstract classes, arrays, primitive types, and void; or if an exception occurred during the constructor

IllegalAccessException - if you are not allowed to access the no-arg constructor because of scoping reasons

SecurityException - if the security check fails

public Classsuper T> getSuperclass()

Get the direct superclass of this class. If this is an interface, Object, a primitive type, or void, it will return null. If this is an array type, it will return Object.

Returns:

the direct superclass of this class

public String toString()

Return the human-readable form of this Object. For an object, this is either "interface " or "class " followed by getName(), for primitive types and void it is just getName().

Overrides:

toString in interface Object

Returns:

the human-readable form of this Object