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Appendix C

The Java Class Library

This appendix provides a general overview of the classes available in the standard Java packages (that is, the classes that are guaranteed to be available in any Java implementation). This appendix is intended for general reference; for more specific information about each variable (its inheritance, variables, and methods), as well as the various exceptions for each package, see the API documentation from Sun at http://java.sun.com. A copy of the 1.0 API documentation is on the CD-ROM included with this book.

java.lang

The java.lang package contains the classes and interfaces that are the core of the Java language.

Interfaces

Cloneable Interface indicating that an object may be copied or cloned
Runnable Methods for classes that want to run as threads

Classes

Boolean Object wrapper for boolean values
Character Object wrapper for char values
Class Run-time representations of classes
ClassLoader Abstract behavior for handling loading of classes
Compiler System class that gives access to the Java compiler
Double Object wrapper for double values
Float Object wrapper for float values
Integer Object wrapper for int values
Long Object wrapper for long values
Math Utility class for math operations
Number Abstract superclass of all number classes (Integer, Float, and so on)
Object Generic Object class, at top of inheritance hierarchy
Process Abstract behavior for processes such as those spawned using methods in the System class
Runtime Access to the Java runtime
SecurityManager Abstract behavior for implementing security policies
String Character strings
StringBuffer Mutable strings
System Access to Java’s system-level behavior, provided in a platform-independent way.
Thread Methods for managing threads and classes that run in threads
ThreadDeath Class of object thrown when a thread is asynchronously terminated
ThreadGroup A group of threads
Throwable Generic exception class; all objects thrown must be a Throwable

java.util

The java.util package contains various utility classes and interfaces, including random numbers, system properties, and other useful classes.

Interfaces

Enumeration Methods for enumerating sets of values
Observer Methods for enabling classes to be observe Observable objects

Classes

BitSet A set of bits
Date The current system date, as well as methods for generating and parsing dates
Dictionary An abstract class that maps between keys and values (superclass of HashTable)
Hashtable A hash table
Observable An abstract class for observable objects
Properties A hash table that contains behavior for setting and retrieving persistent properties of the system or a class
Random Utilities for generating random numbers
Stack A stack (a last-in-first-out queue)
StringTokenizer Utilities for splitting strings into individual “tokens”
VectorA growable array of Objects

java.io

The java.io package provides input and output classes and interfaces for streams and files.

Interfaces

Classes

DataInput Methods for reading machine-independent typed input streams
DataOutput Methods for writing machine-independent typed output streams
FilenameFilterMethods for filtering file names
BufferedInputStream A buffered input stream
BufferedOutputStream A buffered output stream
ByteArrayInputStream An input stream from a byte array
ByteArrayOutputStream An output stream to a byte array
DataInputStream Enables you to read primitive Java types (ints, chars, booleans, and so on) from a sttream in a machine-independent way
DataOutputStream Enables you to write primitive Java data types (ints, chars, booleans, and so on) to a sttream in a machine-independent way
File Represents a file on the host’s file system
FileDescriptor Holds onto the UNIX-like file descriptor of a file or socket
FileInputStream An input stream from a file, constructed using a filename or descriptor
FileOutputStream An output stream to a file, constructed using a filename or descriptor
FilterInputStream Abstract class which provides a filter for input streams (and for adding stream futrctionality such as buffering)
FilterOutputStream Abstract class which provides a filter for output streams (and for adding stream functionality such as buffering)
InputStream An abstract class representing an input stream of bytes; the parent of all input streams in this package
LineNumberInputStream An input stream that keeps track of line numbers
OutputStream An abstract class representing an output stream of bytes; the parent of all output streams in this package
PipedInputStream A piped input stream, which should be connected to a PipedOutputStream to be useful
PipedOutputStream A piped output stream, which should be connected to a PipedInputStream to be useful (together they provide safe communication between threads)
PrintStream An output stream for printing (used by System.out.println(...))
.PushbackInputStream An input stream with a 1-byte push back buffer
RandomAccessFile Provides random access to a file, constructed from filenames, descriptors, or obects
SequenceInputStream Converts a sequence of input streams into a single input stream
StreamTokenizer Converts an input stream into a series of individual tokens
StringBufferInputStream An input stream from a String object

java.net

The java.net package contains classes and interfaces for performing network operations, such as sockets and URLs.

Interfaces

ContentHandlerFactory Methods for creating ContentHandler objects

SocketImplFactory Methods for creating socket implementations (instance of the SocketImpl class)

URLStreamHandlerFactoryMethods for creating URLStreamHandler objects

Classes

ContentHandler Abstract behavior for reading data from a URL connection and constructing the appropriate local object, based on MIME types

DatagramPacket A datagram packet (UDP)

DatagramSocket A datagram socket

InetAddress An object representation of an Internet host (host name, IP address)

ServerSocket A server-side socket

Socket A socket

SocketImpl An abstract class for specific socket implementations

URL An object representation of a URL

URLConnection Abstract behavior for a socket that can handle various Web-based protocols (http, ftp, and so on)

URLEncoder Turns strings into x-www-form-urlencoded format

URLStreamHandler Abstract class for managing streams to object referenced by URLs

java.awt

The java.awt package contains the classes and interfaces that make up the Abstract Windowing Toolkit.

Interfaces

LayoutManager Methods for laying out containers

MenuContainer Methods for menu-related containers

Classes

BorderLayout A layout manager for arranging items in border formation

Button A UI pushbutton

Canvas A canvas for drawing and performing other graphics oper-ations

CardLayout A layout manager for HyperCard-like metaphors

Checkbox A checkbox

CheckboxGroup A group of exclusive checkboxes (radio buttons)

CheckboxMenuItem A toggle menu item

Choice A popup menu of choices

Color An abstract representation of a color

Component The abstract generic class for all UI components

Container Abstract behavior for a component that can hold other components or containers

Dialog A window for brief interactions with users

Dimension An object representing width and height

Event An object representing events caused by the system or based on user input

FileDialog A dialog for getting filenames from the local file system

FlowLayout A layout manager that lays out objects from left to right in rows

Font An abstract representation of a font

FontMetrics Abstract class for holding information about a specific font’s character shapes and height and width information

Frame A top-level window with a title

Graphics Abstract behavior for representing a graphics context, and for drawing and painting shapes and objects

GridBagConstraints Constraints for components laid out using GridBagLayout

GridBagLayout A layout manager that aligns components horizontally and vertically based on their values from GridBagConstraints

GridLayout A layout manager with rows and columns; elements are added to each cell in the grid

Image An abstract representation of a bitmap image

Insets Distances from the outer border of the window; used to lay out components

Label A text label for UI components

List A scrolling list

MediaTracker A way to keep track of the status of media objects being loaded over the Net

Menu A menu, which can contain menu items and is a container on a menubar

MenuBar A menubar (container for menus)

MenuComponent The abstract superclass of all menu elements

MenuItem An individual menu item

Panel A container that is displayed

Point An object representing a point (x and y coordinates)

Polygon An object representing a set of points

Rectangle An object representing a rectangle (x and y coordinates for the top corner, plus width and height)

Scrollbar A UI scrollbar object

TextArea A multiline, scrollable, editable text field

TextComponent The superclass of all editable text components

TextField A fixed-size editable text field

Toolkit Abstract behavior for binding the abstract AWT classes to a platform-specific toolkit implementation

Window A top-level window, and the superclass of the Frame and Dialog classes

java.awt.image

The java.awt.image package is a subpackage of the AWT that provides classes for managing bitmap images.

Interfaces

ImageConsumer Methods for receiving image created by an ImageProducer

ImageObserver Methods to track the loading and construction of an image

ImageProducerMethods for producing image data received by an ImageConsumer

Classes

ColorModel An abstract class for managing color information for images

CropImageFilter A filter for cropping images to a particular size

DirectColorModel A specific color model for managing and translating pixel color values

FilteredImageSource An ImageProducer that takes an image and an ImageFilter object, and produces an image for an ImageConsumer

ImageFilter A filter that takes image data from an ImageProducer, modifies it in some way, and hands it off to an ImageConsumer

IndexColorModel A specific color model for managing and translating color values in a fixed-color map

MemoryImageSource An image producer that gets its image from memory; used after constructing an image by hand

PixelGrabber An ImageConsumer that retrieves a subset of the pixels in an image

RGBImageFilter Abstract behavior for a filter that modifies the RGB values of pixels in RGB images

java.awt.peer

The java.awt.peer package is a subpackage of AWT that provides the (hidden) platform-specific AWT classes (for example, Motif, Macintosh, Windows 95) with platform-independent interfaces to implement. Thus, callers using these interfaces need not know which platform’s window system these hidden AWT classes are currently implementing.

Each class in the AWT that inherits from either Component or MenuComponent has a corresponding peer class. Each of those classes is the name of the Component with -Peer added (for example, ButtonPeer, DialogPeer, and WindowPeer). Because each one provides similar behavior, they are not enumerated here.

java.applet

The java.appletpackage provides applet-specific behavior.

Interfaces

AppletContext Methods to refer to the applet’s context

AppletStub Methods for implementing applet viewers

AudioClip Methods for playing audio files

Classes

Applet The base applet class


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