Overview | Package | Class | Tree | Deprecated | Index | Help
PREV CLASS NEXT CLASS | FRAMES NO FRAMES
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD

## java.lang
Class Class<T>

    java.lang.Object
      java.lang.Class<T>

Type Parameters:
  `T` - the type of the class modeled by this `Class` object. For example, the type of `String.class` is `Class<String>`. Use `Class<?>` if the class being modeled is unknown.

    @TransactionType(value=NOT_SUPPORTED)
    public final class Class<T>

extends Object

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.

`Class` has no public constructor. Instead `Class` objects are constructed automatically by the Java Virtual Machine as classes are loaded.

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());
>      }

Since:
  JDK1.0, CLDC 1.0, Java Card 3.0

Method Summary
`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.
`static Class<?>` | `forName(String className)` Returns the `Class` object associated with the class with the given string name.
`String` | `getName()` Returns the fully-qualified name of the entity (class, interface, array class, primitive type, or void) represented by this `Class` object, as a `String`.
`InputStream` | `getResourceAsStream(String name)` Finds a resource with a given name from the search path used to load this `Class` instance.
`Class<? super T>` | `getSuperclass()` Returns the `Class` representing the superclass of the entity (class, interface, primitive type or void) represented by this `Class`.
`boolean` | `isAnnotation()` Returns true if this `Class` object represents an annotation type.
`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` | `isEnum()` Returns true if and only if this class was declared as an enum in the source code.
`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.
`T` | `newInstance()` Creates a new instance of a class.
`String` | `toString()` Converts the object to a string.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Method Detail

### 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 with the given string name. Given the fully-qualified name for a class or interface, this method attempts to locate, load and link the 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")`

  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 could not be found.
    `SecurityException` - if the permission to dynamically load the class is not granted.
    `Error` - if the function fails for any other reason.
  Since:
    JDK1.0, Java Card 3.0

### newInstance

    public T newInstance()
                  throws InstantiationException,
                         IllegalAccessException

  Creates a new instance of a class.

  Returns:
    a newly allocated instance of the class represented by this object. This is done exactly as if by a `new` expression with an empty argument list.
  Throws:
    `IllegalAccessException` - if the class or initializer is not accessible.
    `InstantiationException` - if an application tries to instantiate an abstract class or an interface, or if the instantiation fails for some other reason.
  Since:
    JDK1.0

### 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.

### isAnnotation

    public boolean isAnnotation()

  Returns true if this `Class` object represents an annotation type. Note that if this method returns true, `isInterface()` would also return true, as all annotation types are also interfaces.

  Returns:
    `true` if this class object represents an annotation type; `false` otherwise
  Since:
    JDK1.5, Java Card 3.0

### 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
  Since:
    JDK1.5, Java Card 3.0

### 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

### getName

    public String getName()

  Returns the fully-qualified 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 class of arrays, then the internal form of the name consists of the name of the element type in Java signature format, preceded by one or more "`[`" characters representing the depth of array nesting. Thus:

  >      (new Object[3]).getClass().getName()

  returns "`[Ljava.lang.Object;`" and:

  >      (new int[3][4][5][6][7][8][9]).getClass().getName()

  returns "`[[[[[[[I`". The encoding of element type names is as follows:

  >       B            byte
  >       C            char
  >       I            int
  >       J            long
  >       L<i>classname;</i>  class or interface
  >       S            short
  >       Z            boolean

  The class or interface name `classname` is given in fully qualified form as shown in the example above.

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

### getResourceAsStream

    public InputStream getResourceAsStream(String name)

  Finds a resource with a given name from the search path used to load this `Class` instance. This method returns `null` if no resource with this name is found.

  The resource names can be represented in two different formats: absolute or relative.

  Absolute format:

  `/packagePathName/resourceName`

  Relative format:

  `resourceName`

  In the absolute format, the programmer provides a fully qualified name that includes both the full path and the name of the resource inside the JAR file. In the path names, the character "/" is used as the separator.

  In the relative format, the programmer provides only the name of the actual resource. Relative names are converted to absolute names by the system by prepending the resource name with the fully qualified package name of class upon which the `getResourceAsStream` method was called.

  The rules for searching resources associated with a given class are described in chapter 6 of Runtime Environment Specification for the Java Card Platform, Connected Edition.

  Parameters:
    `name` - name of the desired resource
  Returns:
    a `java.io.InputStream` object.
  Throws:
    `NullPointerException` - if the specified name parameter 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.
  The enabling control of assertions is implementation dependent.

  Returns:
    the desired assertion status of the specified class.
  Since:
    JDK1.4, Java Card 3.0

### getSuperclass

    public Class<? super T> 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.

Overview | Package | Class | Tree | Deprecated | Index | Help
PREV CLASS NEXT CLASS | FRAMES NO FRAMES
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD

Copyright (c) 2009 Sun Microsystems, Inc. All rights reserved.