• Appendix D
  • Glossary

Appendix D

Glossary

Abstract Windowing Toolkit The set of Java classes that are used to display and control a graphical user interface. Also called the AWT.

ActiveX A way to run programs on World Wide Web pages that was developed by Microsoft. ActiveX is an extension of the Component Object Model, and it is a rival of sorts to Java.

applet A Java program that runs as part of a World Wide Web page.

appletviewer The Java Developer's Kit tool that can display applets that are included on a World Wide Web page.

application A Java program that runs locally on your computer rather than as part of a World Wide Web page.

argument Extra information that is sent to a program when it is run or information that is sent to a method in a program when it begins.

array A group of variables that share the same name and store the same kind of information. Each variable in the group is called an element, and elements are numbered so that they can be distinguished from each other.

ASCII text file A text file that does not contain any special character or formatting commands such as centering, boldfaced text, and different point sizes.

attribute Part of an HTML tag that affects what the tag does. Also, in object-oriented programming, it is a thing that describes an object and distinguishes it from other objects. These attributes are stored in variables.

autodialer Software that uses a modem to dial a series of phone numbers in sequence.

BASIC A language designed for use by beginning programmers. Dozens of different versions of BASIC are available.

behavior The things that an object does, as conducted by the methods of the object.

bit An integer that can equal 0 or 1. Each byte is made up of 8 bits.

block A group of statements in a Java program. Blocks begin with a { mark and end with a } mark.

block statement Another term for a block.

Boolean A value that can be either true or false.

browser Software that can be used to view World Wide Web pages on the Internet.

bug An error in a program that must be fixed in order for the program to operate correctly.

byte A number that can store 256 integer values--either 0 to 255 or, in the case of Java, -127 to 128. A byte consists of 8 bits.

bytecode The compiled form of a Java source file that is run by a Java interpreter.

C++ An extension of the C programming language developed by Bjarne Stroustrop that includes features such as object-oriented programming, multiple inheritance, and the use of pointers.

character A single letter, number, punctuation mark, or other symbol.

check box A user interface component that presents a box next to a line of text. The box can be checked or unchecked by the user.

choice list A user interface component that presents a pop-up list of choices from which a single choice can be made. Only one of the selections is visible unless the pop-up list is being displayed.

class A master copy of an object that determines what behavior and attributes an object should have. Because every Java program is also a class, programs also are called classes.

class method A method that is associated with a class of objects instead of a specific object.

class variable A variable that is associated with a class of objects instead of an object and has a value specific to the class.

command line A way to operate a computer entirely with the keyboard by typing commands at a prompt. MS-DOS is the most popular operating system to use a command line.

comments Lines in a source file that are provided strictly for the benefit of humans trying to understand the program.

compiler A program that turns a source file into a computer program by interpreting the whole file beforehand and creating a compiled file that can be run. This program is more efficient than an interpreter but is slower to debug.

component An item such as a clickable button or scrollbar that can be manipulated by a user in a program.

concatenate To link two things together. This term is often used to describe the process of attaching two strings to each other so they can be displayed together.

conditional A statement that causes something to happen only if a specific condition is met.

constant A variable that cannot change in value throughout a program.

constructor A special method that only is handled when an object is being created.

container A component that can contain other components in a graphical user interface.

decrement To subtract one from something.

debug The process of fixing bugs in a computer program.

double-buffering Drawing graphics to an off-screen work area first in order to improve the quality of animation.

element A specific variable of an array.

event-handling Responding to a user's mouse and keyboard use in a program's graphical user interface.

expressions Statements that involve a mathematic equation or that change the value of something.

floating-point numbers Numbers that might include a decimal point.

GIF file An image file format that was developed by CompuServe.

GIF 89a file A version of the GIF format that includes support for transparent colors.

graphical user interface The buttons, text fields, and other components of a program that enable a user to interact with the program using a mouse and keyboard. Also called a GUI.

hierarchy A pyramid-shaped grouping of classes in which the topmost class is the superclass of all classes below it.

HSB values A way of defining a color by determining the percentage of hue, saturation, and brightness that exist in the color.

hypertext markup language HTML, the simple programming language used to present information on World Wide Web pages.

increment To add one to something.

inheritance The capability of a class of objects to automatically have the attributes and behavior of another object. The extent of this capability is determined by the class' position in the class hierarchy.

integer A whole number.

interface A special type of class that enables a class to inherit methods it would not be able to use through inheritance alone.

Internet Explorer Web browser software from Microsoft that can run Java programs.

interpreter A program that turns a source file into a computer program by interpreting each line one at a time. An interpreted language runs programs more slowly than a compiled language does, but it is easier to debug.

initialization The process of setting something up for the first time in a program. This term is used often in reference to variables.

Java An object-oriented programming language developed by Sun Microsystems that was first released to the public in 1995. Java programs are compiled into class files that can run on any computer platform that has a Java interpreter.

java The interpreter that is part of the Java Developer's Kit.

Java Developer's Kit A free set of tools from Sun Microsystems that makes it possible to write and test Java programs in a command-line environment.

Java WorkShop Software from Sun Microsystems that enables Java programs to be written in a graphical, point-and-click environment.

javac The compiler that is included with the Java Developer's Kit.

JavaScript An interpreted programming language unrelated to Java that offers limited programming capabilities on a Web page. The source code of JavaScript programs is included as text on Web pages.

JPG file An image file format developed by the Joint Photographic Expert Groups, also called a JPEG file. This format is considered the best for presenting photographic images without taking up a lot of disk space.

layout manager An object that controls how components will be arranged in a graphical user interface.

logic error A bug that causes a program to do something it isn't supposed to do but doesn't prevent the program from running. These errors must be found during testing, but they can be hard to find.

long integers Integers that are larger than 2.14 billion or smaller than -2.14 billion.

loop A statement or set of statements that will be repeated in a program.

method A way to accomplish a task in a Java program. Methods begin with a { and end with a }.

multiple inheritance The capability of a class of objects to inherit attributes and behavior from more than one superclass.

multithreading The capability of a program or operating system to run more than one program at the same time. Also known as multitasking.

Navigator Web browser software from Netscape that includes the capability to run Java programs in its current versions.

newline A special character represented by `\N' that causes the display of text to continue at the leftmost column of the next line.

object variable A variable that is associated with an object and has a value that is specific to that object.

object-oriented programming A way of thinking of computer programs as a group of objects that work together, each object containing everything it needs to handle a specific task.

operator The part of an expression that causes a mathematical operation to occur, such as addition or multiplication, or tests a condition such as equality.

overriding Creating a method or variable in a subclass that replaces something it inherited from its superclass.

parameters Extra information sent to a Java applet when it runs that is included using an HTML tag on a World Wide Web page.

platform A computer operating system and central processing unit.

platform-independence The ability of software to run without modification on several different platforms.

point and click The ability to control a program by using a mouse device and clicking its buttons.

pointer A variable in a program that points to where another value is stored. Java does not include pointers.

program A set of instructions that tell a computer what to do. Also called software.

pull-down menus Menus in a program that you use by clicking a menu title, holding down the mouse, and releasing it over the item you want.

RGB values A way of defining the color of something by specifying the percentage of red, green, and blue that exist in the color.

scope The area of a program in which a variable exists, defined by the nearest { and } marks that surround the variable. A variable's scope is the block in which the variable was created, and it cannot be used outside of that scope.

short integers Integers that can range from -32,768 to 32,767.

software A computer program or group of computer programs designed to work together.

source file The text file created by a programmer that will be turned into a computer program by an interpreter or a compiler. Also called source code.

statement One of the instructions that is handled by the computer when it runs a program.

string A group of characters that represent one or more lines of text.

subclass A class that is below another class in a hierarchy, inheriting attributes and behavior from the classes that are above it.

superclass A class that is above another class in a hierarchy, giving its attributes and behavior to any classes that are below it.

syntax error A bug in a program that is caused by using a statement or other part of the language incorrectly. Syntax errors are easier to find than other errors because they cause error messages.

tab A special character represented by `\t' that causes text to continue at the next column, based on how wide columns have been defined. This character is used to format text for display.

tag An HTML command used on a World Wide Web page to format text, present images, run Java applets, or accomplish similar things. Tags are enclosed within < and > marks.

ternary operator An operator represented by ? that uses a conditional test to set a value. If the test is true, the first value is used, and if the test is false, the second value is used.

text area A user interface component that presents a text field where a user can enter more than one line of text.

text editor Another term for word processor.

text field A user interface component that presents an area where a user can enter a single line of text.

thread A single program that can run as part of a multithreaded system.

variables Special storage places where a computer program can store information.

VBScript An interpreted programming language from Microsoft that offers limited programming capabilities on a Web page. VBScript is based on Visual Basic, and its source code is included as text on Web pages.

Visual Basic A programming language from Microsoft that speeds up the process of developing windowing software for Microsoft systems.

Visual C++ An object-oriented programming language from Microsoft with extensive support for windowing and many other Windows-specific technologies.

word processor A computer program used for the editing and presentation of text documents.