Abbreviated Glossary

Terms taken from the Glossary below that are important are you start to understand OOP

abstract class

A class that contains one or more abstract methods, and therefore can never be instantiated. Abstract classes are defined so that other classes can extend them and make them concrete by implementing the abstract methods.

abstract method

A method that has no implementation.

actual parameter list

The arguments specified in a particular method call. See also

appliances

Networked devices such as printers, Java(TM) technology-enabled terminals, and clients, that are managed using applications built using the Java Management API (JMAPI).

applet

A program written in the Java(TM) programming language to run within a web browser compatible with the Java platform, such as HotJava(TM) or Netscape Navigator(TM).

argument

A data item specified in a method call. An argument can be a literal value, a variable, or an expression.

array

A collection of data items, all of the same type, in which each item's position is uniquely designated by an integer.

ASCII

American Standard Code for Information Interchange. A standard assignment of 7-bit numeric codes to characters. See also Unicode.

binary operator

An operator that has two arguments.

bit

The smallest unit of information in a computer, with a value of either 0 or 1.

block

In the Java(TM) programming language, any code between matching braces. Example: { x = 1; }.

boolean

Refers to an expression or variable that can have only a true or false value. The Java(TM) programming language provides the boolean type and the literal values true and false.

break

A Java(TM) programming language keyword used to resume program execution at the statement immediately following the current statement. If followed by a label, the program resumes execution at the labeled statement.

byte

A sequence of eight bits. The Java(TM) programming language provides a corresponding byte type.

bytecode

Machine-independent code generated by the Java(TM) compiler and executed by the Java interpreter.

case

A Java(TM) programming language keyword that defines a group of statements to begin executing if a value specified matches the value defined by a preceding "switch" keyword.

casting

Explicit conversion from one data type to another.

catch

A Java(TM) programming language keyword used to declare a block of statements to be executed in the event that a Java exception, or run time error, occurs in a preceding "try" block.

char

A Java(TM) programming language keyword used to declare a variable of type character.

class

In the Java(TM) programming language, a type that defines the implementation of a particular kind of object. A class definition defines instance and class variables and methods, as well as specifying the interfaces the class implements and the immediate superclass of the class. If the superclass is not explicitly specified, the superclass will implicitly be Object.

comment

In a program, explanatory text that is ignored by the compiler. In programs written in the Java(TM) programming language, comments are delimited using // or /*...*/.

constructor

A pseudo-method that creates an object. In the Java(TM) programming language, constructors are instance methods with the same name as their class. Constructors are invoked using the new keyword.

continue

A Java(TM) programming language keyword used to resume program execution at the end of the current loop. If followed by a label, "continue" resumes execution where the label occurs.

declaration

A statement that establishes an identifier and associates attributes with it, without necessarily reserving its storage (for data) or providing the implementation (for methods). See also definition.

do

A Java(TM) programming language keyword used to declare a loop that will iterate a block of statements. The loop`s exit condition can be specified with the "while" keyword.

double

A Java(TM) programming language keyword used to define a variable of type double.

double precision

In the Java(TM) programming language specification, describes a floating point number that holds 64 bits of data. See also single precision.

else

A Java(TM) programming language keyword used to execute a block of statements in the case that the test condition with the "if" keyword evaluates to false.

exception

An event during program execution that prevents the program from continuing normally; generally, an error. The Java(TM) programming language supports exceptions with the try, catch, and throw keywords. See also exception handler.

exception handler

A block of code that reacts to a specific type of exception. If the exception is for an error that the program can recover from, the program can resume executing after the exception handler has executed.

executable content

An application that runs from within an HTML file. See also applet.

extends

Class X extends class Y to add functionality, either by adding fields or methods to class Y, or by overriding methods of class Y. An interface extends another interface by adding methods. Class X is said to be a subclass of class Y. See also derived from.

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field

A data member of a class. Unless specified otherwise, a field is not static.

final

A Java(TM) programming language keyword. You define an entity once and cannot change it or derive from it later. More specifically: a final class cannot be subclassed, a final method cannot be overridden and a final variable cannot change from its initialized value.

float

A Java(TM) programming language keyword used to define a floating point number variable.

for

A Java(TM) programming language keyword used to declare a loop that reiterates statements. The programmer can specify the statements to be executed, exit conditions, and initialization variables for the loop.

FTP

The basic Internet File Transfer Protocol. FTP, which is based on TCP/IP, enables the fetching and storing of files between hosts on the Internet. See also TCP/IP.

GUI

Graphical User Interface. Refers to the techniques involved in using graphics, along with a keyboard and a mouse, to provide an easy-to-use interface to some program.

HTML

HyperText Markup Language. This is a file format, based on SGML, for hypertext documents on the Internet. It is very simple and allows for the embedding of images, sounds, video streams, form fields and simple text formatting. References to other objects are embedded using URLs.

HTTP

HyperText Transfer Protocol. The Internet protocol, based on TCP/IP, used to fetch hypertext objects from remote hosts. See also TCP/IP.

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if

A Java(TM) programming language keyword used to conduct a conditional test and execute a block of statements if the test evaluates to true.

implements

A Java(TM) programming language keyword optionally included in the class declaration to specify any interfaces that are implemented by the current class.

import

A Java(TM) programming language keyword used at the beginning of a source file that can specify classes or entire packages to be referred to later without including their package names in the reference.

inheritance

The concept of classes automatically containing the variables and methods defined in their supertypes. See also superclass, subclass.

instance

An object of a particular class. In programs written in the Java(TM) programming language, an instance of a class is created using the new operator followed by the class name.

instance method

Any method that is invoked with respect to an instance of a class. Also called simply a method. See also class method.

instance variable

Any item of data that is associated with a particular object. Each instance of a class has its own copy of the instance variables defined in the class. Also called a field. See also class variable.

int

A Java(TM) programming language keyword used to define a variable of type integer.

interface

A Java(TM) programming language keyword used to define a collection of method definitions and constant values. It can later be implemented by classes that define this interface with the "implements" keyword.

Internet

An enormous network consisting of literally millions of hosts from many organizations and countries around the world. It is physically put together from many smaller networks and data travels by a common set of protocols.

IP

Internet Protocol. The basic protocol of the Internet. It enables the unreliable delivery of individual packets from one host to another. It makes no guarantees about whether or not the packet will be delivered, how long it will take, or if multiple packets will arrive in the order they were sent. Protocols built on top of this add the notions of connection and reliability. See also TCP/IP.

interpreter

A module that alternately decodes and executes every statement in some body of code. The Java(TM) interpreter decodes and executes bytecode for the Java virtual machine*. See also compiler, runtime system.

keyword

The Java(TM) programming language sets aside words as keywords - these words are reserved by the language itself and therefore are not available as names for variables or methods.

literal

The basic representation of any integer, floating point, or character value. For example, 3.0 is a double-precision floating point literal, and "a" is a character literal.

local variable

A data item known within a block, but inaccessible to code outside the block. For example, any variable defined within a method is a local variable and can't be used outside the method.

long

A Java(TM) programming language keyword used to define a variable of type long.

member

A field or method of a class. Unless specified otherwise, a member is not static.

method

A function defined in a class. See also instance method, class method. Unless specified otherwise, a method is not static.

multithreaded

Describes a program that is designed to have parts of its code execute concurrently. See also thread.

new

A Java(TM) programming language keyword used to create an instance of a class.

null

A Java(TM) programming language keyword used to specify an undefined value for reference variables.

object

The principal building blocks of object-oriented programs. Each object is a programming unit consisting of data (instance variables) and functionality (instance methods). See also class.

object-oriented design

A software design method that models the characteristics of abstract or real objects using classes and objects.

overloading

Using one identifier to refer to multiple items in the same scope. In the Java(TM) programming language, you can overload methods but not variables or operators.

private

A Java(TM) programming language keyword used in a method or variable declaration. It signifies that the method or variable can only be accessed by other elements of its class.

protected

A Java(TM) programming language keyword used in a method or variable declaration. It signifies that the method or variable can only be accessed by elements residing in its class, subclasses, or classes in the same package.

public

A Java(TM) programming language keyword used in a method or variable declaration. It signifies that the method or variable can be accessed by elements residing in other classes.

reference

A data element whose value is an address.

return

A Java(TM) programming language keyword used to finish the execution of a method. It can be followed by a value required by the method definition.

scope

A characteristic of an identifier that determines where the identifier can be used. Most identifiers in the Java(TM) programming environment have either class or local scope. Instance and class variables and methods have class scope; they can be used outside the class and its subclasses only by prefixing them with an instance of the class or (for class variables and methods) with the class name. All other variables are declared within methods and have local scope; they can be used only within the enclosing block.

Secure Socket Layer (SSL)

A protocol that allows communication between a Web browser and a server to be encrypted for privacy.

short

A Java(TM) programming language keyword used to define a variable of type short.

single precision

In the Java(TM) language specification, describes a floating point number with 32 bits of data. See also double precision.

static

A Java(TM) programming language keyword used to define a variable as a class variable. Classes maintain one copy of class variables regardless of how many instances exist of that class. "static" can also be used to define a method as a class method. Class methods are invoked by the class instead of a specific instance, and can only operate on class variables.

static field

Another name for class variable.

static method

Another name for class method.

subarray

An array that is inside another array.

subclass

A class that is derived from a particular class, perhaps with one or more classes in between. See also superclass, supertype.

superclass

A class from which a particular class is derived, perhaps with one or more classes in between. See also subclass, subtype.

super

A Java(TM) programming language keyword used to access members of a class inherited by the class in which it appears.

switch

A Java(TM) programming language keyword used to evaluate a variable that can later be matched with a value specified by the "case" keyword in order to execute a group of statements.

TCP/IP

Transmission Control Protocol based on IP. This is an Internet protocol that provides for the reliable delivery of streams of data from one host to another. See also IP.

Technology Compatibility Kit (TCK)

A test suite, a set of tools, and other requirements used to certify an implementation of a particular Sun technology conformant both to the applicable specifications and to Sun or Sun-designated reference implementations.

this

A Java(TM) programming language keyword that can be used to represent an instance of the class in which it appears. "this" can be used to access class variables and methods.

thread

The basic unit of program execution. A process can have several threads running concurrently, each performing a different job, such as waiting for events or performing a time-consuming job that the program doesn't need to complete before going on. When a thread has finished its job, the thread is suspended or destroyed. See also process.

throws

A Java(TM) programming language keyword used in method declarations that specify which exceptions are not handled within the method but rather passed to the next higher level of the program.

try

A Java(TM) programming language keyword that defines a block of statements that may throw a Java language exception. If an exception is thrown, an optional "catch" block can handle specific exceptions thrown within the "try" block. Also, an optional "finally" block will be executed regardless of whether an exception is thrown or not.

URL

Uniform Resource Locator. A standard for writing a text reference to an arbitrary piece of data in the WWW. A URL looks like "protocol://host/localinfo" where protocol specifies a protocol to use to fetch the object (like HTTP or FTP), host specifies the Internet name of the host on which to find it, and localinfo is a string (often a file name) passed to the protocol handler on the remote host.

variable

An item of data named by an identifier. Each variable has a type, such as int or Object, and a scope. See also class variable, instance variable, local variable.

virtual machine

An abstract specification for a computing device that can be implemented in different ways, in software or hardware. You compile to the instruction set of a virtual machine much like you'd compile to the instruction set of a microprocessor. The Java(TM) virtual machine* consists of a bytecode instruction set, a set of registers, a stack, a garbage-collected heap, and an area for storing methods.

volatile

A Java(TM) programming language keyword used in variable declarations that specifies that the variable is modified asynchronously by concurrently running threads.

wait

A UNIX® command which will wait for all background processes to complete, and report their termination status.

while

A Java(TM) programming language keyword used to declare a loop that iterates a block of statements. The loop`s exit condition is specified as part of the while statement.

world readable files

Files on a file system that can be viewed (read) by any user. For example: files residing on web servers can only be viewed by Internet users if their permissions have been set to world readable.

WWW

World Wide Web. The web of systems and the data in them that is the Internet. See also Internet.