Java Language Glossary

java.util 
Class AbstractList <E>

java.lang.Object
  extended by java.util.AbstractCollection<E>
      extended by java.util.AbstractList<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, List<E>
Direct Known Subclasses:
AbstractSequentialList, ArrayList, Vector

Abstract Windowing Toolkit (AWT)

The Abstract Windowing Toolkit is a section of the Java API that supports basic windowing and GUI features.

Access modifier

Access modifiers define different levels of access for class members including private, protected, public, and a default access level.

Applet

Graphical Java programs that execute within a Web page

AppletViewer

A utility included with the Java 2 SDK that allows you to test applets without using a Web browser

Application Programming Interface (API)

The set of Java packages and classes included in the Java 2 SDK that programmers use to create Java programs

Array

Special constructs in Java that allow you to store a list of items of the same data type

Branch statement

Java supports two different kinds of branch statements. The if-else is the most commonly used, and it is useful in situations where you need to conditionally execute one section of code or another. Java's other branch statement, the switch statement, is designed to choose between multiple branches of code.

Break statement

The break statement is used to exit out of a branch or loop

Buffered I/O

Buffered I/O is a special type of I/O where data is written to a temporary buffer instead of to an actual stream. When the buffer is full, all of the data in the buffer is written to the stream. Buffered I/O is more efficient than non-buffered I/O since data is transferred to and from a physical device in large blocks.

Bytecode

The executable form of Java code, which is capable of being executed in the Java runtime system

Catch clause

The catch clause is the part of the try-catch construct that is used to catch any exceptions that may be thrown by code in the try clause.

Class

A template that defines the implementation of an object, effectively acting as a blueprint for the object. A class defines data and methods and is a unit of organization in a Java program.

Client

A client is a program that requests and displays information from a special program called a server. This type of information exchange between a client and server is known as a client/server architecture.

Command-line arguments

Information passed into a command-line application that somehow controls the way the application runs

Comments

Comments are used to document code for the purposes of the programmer. Java supports three different types of comments: //, /* */, and /** */.

Compound statement

A compound statement is a block of code that is surrounded by curly braces ({}). Compound statements allow you to use multiple lines of code in situations where a single statement is expected. A good example is the code executed in the branch of an if statement.

Conditional operator

The conditional operator acts a like a shorthand if-else statement. It evaluates a test expression and conditionally evaluates another expression based on the test.

Data types

Data types dictate the type of information that can be stored in a variable. Java supports a wide range of simple data types such as int, long, float, boolean, and char. Composite data types in Java are implemented as objects. An example of a composite data type is String.

Exception

An exceptional situation that a program doesn't know how to handle is known as an exception. An example of an exception is attempting to divide a number by zero or the system running out of memory.

Expression

An expression usually involves an equal sign (=) and somehow manipulates one or more variables or values

Finally clause

The finally clause is used in conjunction with the try-catch construct to place code that is always executed regardless of whether an exception is thrown.

Graphical User Interface (GUI)

The program elements involved in communicating with the user through visual cues, typically utilizing both the keyboard and mouse

Graphics class

The Graphics class represents an abstract drawing surface called a graphics context, and is logically equivalent to a piece of paper. Java uses graphics contexts to help abstract the drawing process, which allows you to use the same drawing code to draw to different graphical devices such as monitors and printers.

Graphics context

A graphics context is an abstract drawing surface that is logically equivalent to a piece of paper.

Graphics Interchange Format (GIF)

GIF is an image format that is useful for storing non-photographic images such as illustrations and diagrams; GIF image files typically have a .gif file extension.

Graphics primitives

Graphics primitives are basic geometric shapes such as lines, rectangles, squares, ovals, circles, polygons, and arcs.

Hypertext Markup Language (HTML)

The formatting language used to create Web pages

Identifier

Tokens that represent unique names for variables, methods, classes, packages and any other named Java construct

Inheritance

The ability to derive new classes from existing classes in object-oriented programming

Interface

An interface is a set of methods that Java classes can implement.

Internet Protocol (IP) address

An IP address is a number that is used to uniquely identify computers connected to the Internet.

Java 2 Software Development Kit (SDK)

A standard suite of tools, utilities, and related resources used to build Java applets and applications

Java compiler

The tool used to compile Java source code into executable Java programs

Java Interpreter

A program responsible for translating Java bytecode into native code that can execute on a given platform

Joint Photographic Experts Group (JPEG)

JPEG is an image format that provides a highly efficient means of storing photographic images; JPEG image files typically have a .jpg or .jpeg file extension.

Keywords

Keywords are special identifiers set aside as Java programming constructs. Typical keywords in Java include int, class, for, while, new, private, and switch, to name a few.

Literals

Literals are constant values such as numbers and strings

Loop

There are three types of loops used in Java: for loops, while loops, and do loops

main() method

The method within a Java application that is called by the Java interpreter to run the application

Message

In object-oriented programming, sending a message to an object to invoke a method is similar to calling a procedure in structured programming languages

Method

An isolated section of code in an object that performs a particular function

Multithreading

Multithreading is the capability of a program to have multiple paths of execution called threads.

Object

A collection of data and the procedures (methods) that act on that data.

Object class

The class that forms the root of the Java class hierarchy. The Object class serves as the basis for all Java classes, including the classes in the Java API.

Object-oriented programming (OOP)

The implementation of a program or algorithm using objects

Operator

A programming construct that performs an evaluation or computation on a data object or objects

Overload

To use the same name for several items in the same scope

Override

To replace an inherited method with a newer version

Package

A package is a collection of reusable classes and interfaces.

Parameter

A name and value pair identified by the name and value attributes of the PARAM element used inside an APPLET element

Protocol

A protocol is a set of rules and standards that govern how network communication works. Protocols determine how computers communicate with each other over a network.

Separators

Separators are symbols used to inform the Java compiler of how code elements are grouped

Server

A server is a program that acts as an information source to special programs called clients. This type of information exchange between a client and server is known as a client/server architecture.

Socket

A socket is a "fitting" used to connect a stream of network data to a Java program.

Standard I/O

Standard I/O is the most basic form of input and output available to a Java program. Java standard I/O is text-based, and operates under the premise that the computer has a standard input device (keyboard) and a standard output device (monitor).

Stream

A stream is a medium through which data is transferred. A stream acts sort of like a pipe in the real world, except that it shuttles moving data instead of water or gas. Data is transferred through a stream one byte at a time, and can be directed in different ways.

String

A Java object that represents textual information. Although you can think of a string in Java as a series of characters, strings are implemented in the String class.

Thread synchronization

Thread synchronization is the process of structuring threads so that they never interrupt each other while performing sensitive tasks.

Throwing (an exception)

When an exceptional condition is encountered in a Java program, an exception is thrown, which means that a special exception object is created and passed out of the current context. The idea is that a higher context will be more capable of handling the exception.

Token

The smallest code element in a program that is meaningful to the compiler

Try clause

The try clause is the part of the try-catch construct where code is placed that can potentially throw an exception. You then catch any exceptions that may be thrown in one or more catch clauses.

Uniform Resource Locator (URL)

A URL is a text address used to identify sites on the Internet.

Variables

Variables are locations in memory that are used to store information. You can think of variables as storage containers designed to hold data of a certain type.