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Reference
Glossary
Note
abstract A
Java keyword used in a class definition to specify that a class is not to be
instantiated, but rather inherited by other classes. An abstract class can
have abstract methods that are not implemented in the abstract class, but in
subclasses. 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. A
method that has no implementation. A
collection of graphical user interface (GUI) components that were implemented
using native-platform versions of the components. These components provide
that subset of functionality which is common to all native platforms. Largely
supplanted by the Project Swing component set. See also Swing.
The
methods by which interactions with resources are limited to collections of
users or programs for the purpose of enforcing integrity, confidentiality, or
availability constraints. ACID The
acronym for the four properties guaranteed by transactions: atomicity,
consistency, isolation, and durability. The
arguments specified in a particular method call. See also formal
parameter list. API Application
Programming Interface. The specification of how a programmer writing an
application accesses the behavior and state of classes and objects. applet A
component that typically executes in a Web browser, but can execute in a
variety of other applications or devices that support the applet programming
model. 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. American
Standard Code for Information Interchange. A standard assignment of 7-bit
numeric codes to characters. See also Unicode. atomic Refers
to an operation that is never interrupted or left in an incomplete state
under any circumstance. authentication The
process by which an entity proves to another entity that it is acting on
behalf of a specific identity. authorization See
access control. autoboxing Automatic
conversion between reference and primitive types. bean A
reusable software component that conforms to certain design and naming
conventions. The conventions enable beans to be easily combined to create an
application using tools that understand the conventions. 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. bitwise operator An
operator that manipulates the bits of one or more of its operands
individually and in parallel. Examples include the binary logical operators
(&, |, ^), the binary shift operators (<<, >>, >>>)
and the unary one's complement operator (~). block In
the Java programming language, any code between matching braces. Example: boolean Refers
to an expression or variable that can have only a true or false value. The
Java programming language provides the boolean type and the literal values
true and false. break A
Java 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. Java provides a corresponding bytecode Machine-independent
code generated by the Java compiler and executed by the Java interpreter. case A Java keyword that defines a group of
statements to begin executing if a value specified matches the value defined
by a preceding casting Explicit
conversion from one data type to another. catch A Java 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 char A Java keyword used to declare a variable of
type character. In
the Java 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 A
method that is invoked without reference to a particular object. Class
methods affect the class as a whole, not a particular instance of the class.
Also called a static method. See also instance method. A
data item associated with a particular class as a whole--not with particular
instances of the class. Class variables are defined in class definitions.
Also called a static field. See also instance variable. classpath An
environmental variable which tells the Java virtual machine1
and Java technology-based applications where to find the class libraries,
including user-defined class libraries. In
the client/server model of communications, the client is a process that
remotely accesses resources of a compute server, such as compute power and
large memory capacity. codebase Works
together with the comment In
a program, explanatory text that is ignored by the compiler. In programs
written in the Java programming language, comments are delimited using commit The
point in a transaction when all updates to any resources involved in the
transaction are made permanent. compilation unit The
smallest unit of source code that can be compiled. In the current
implementation of the Java platform, the compilation unit is a file. A
program to translate source code into code to be executed by a computer. The
Java compiler translates source code written in the Java programming language
into bytecode for the Java virtual machine1.
See also interpreter. compositing The
process of superimposing one image on another to create a single image. constructor A
pseudo-method that creates an object. In the Java programming language,
constructors are instance methods with the same name as their class.
Constructors are invoked using the const A
reserved Java keyword not used by current versions of the Java programming
language. continue A
Java keyword used to resume program execution at the end of the current loop.
If followed by a label, conversational state The
field values of a session bean plus the transitive closure of the objects
reachable from the bean's fields. The transitive closure of a bean is defined
in terms of the serialization protocol for the Java programming language,
that is, the fields that would be stored by serializing the bean instance. CORBA Common
Object Request Broker Architecture. A language independent, distributed
object model specified by the Object Management Group (OMG). core class A
public class (or interface) that is a standard member of the Java Platform.
The intent is that the core classes for the Java platform, at minimum, are
available on all operating systems where the Java platform runs. A program
written entirely in the Java programming language relies only on core
classes, meaning it can run anywhere. .
core packages The
required set of APIs in a Java platform edition which must be supported in
any and all compatible implementations. credentials The
information describing the security attributes of a principal. Credentials
can be acquired only through authentication or delegation. critical section A
segment of code in which a thread uses resources (such as certain instance
variables) that can be used by other threads, but that must not be used by
them at the same time. 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. default A
Java keyword optionally used after all definition A
declaration that reserves storage (for data) or provides implementation (for
methods). See also declaration. delegation An
act whereby one principal authorizes another principal to use its identity or
privileges with some restrictions. deprecation Refers
to a class, interface, constructor, method or field that is no longer
recommended, and may cease to exist in a future version. Class
X is "derived from" class Y if class X extends class Y. See
also subclass, superclass.
distributed Running
in more than one address space. distributed application An
application made up of distinct components running in separate runtime
environments, usually on different platforms connected through a network.
Typical distributed applications are two-tier (client/server), three-tier
(client/middleware/server), and n-tier (client/multiple middleware/multiple
servers). do A Java keyword used to declare a loop that
will iterate a block of statements. The loop's exit condition can be
specified with the DOM Document Object Model. A
tree of objects with interfaces for traversing the tree and writing an XML
version of it, as defined by the W3C specification. double A Java
keyword used to define a variable of type In the Java programming
language specification, describes a floating point number that holds 64 bits
of data. See also single
precision. DTD Document Type Definition. A
description of the structure and properties of a class of XML files. else A Java keyword used to
execute a block of statements in the case that the test condition with the EmbeddedJava Technology The availability of Java 2
Platform, Micro Edition technology under a restrictive license agreement that
allows a licensee to leverage certain Java technologies to create and deploy
a closed-box application that exposes no APIs. encapsulation The localization of
knowledge within a module. Because objects encapsulate data and
implementation, the user of an object can view the object as a black box that
provides services. Instance variables and methods can be added, deleted, or
changed, but as long as the services provided by the object remain the same,
code that uses the object can continue to use it without being rewritten. See
also instance variable,
instance
method. enum A Java keyword used to
declare an enumerated type. enumerated type A type whose legal values
consist of a fixed set of constants. exception An event during program
execution that prevents the program from continuing normally; generally, an
error. The Java 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. A data member of a class.
Unless specified otherwise, a field is not static. final A Java
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. finally A Java
keyword that executes a block of statements regardless of whether a Java
Exception, or run time error, occurred in a block defined previously by the float A Java keyword used to
define a floating point number variable. for A Java
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 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. The parameters specified in
the definition of a particular method. See also actual parameter list. garbage collection The automatic detection and
freeing of memory that is no longer in use. The Java runtime system performs
garbage collection so that programmers never explicitly free objects. generic A class, interface, or
method that declares one or more type variables. These type variables are
known as type parameters. A generic declaration defines a set of
parameterized types, one for each possible invocation of the type parameter
section. At runtime, all of these parameterized types share the same class,
interface, or method. goto This is
a reserved Java keyword. However, it is not used by current versions of the
Java programming language. group A collection of principals
within a given security policy domain. 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. The numbering system that
uses 16 as its base. The marks 0-9 and a-f (or equivalently A-F) represent
the digits 0 through 15. In programs written in the Java programming
language, hexadecimal numbers must be preceded with 0x. See also octal. A classification of
relationships in which each item except the top one (known as the root) is a
specialized form of the item above it. Each item can have one or more items
below it in the hierarchy. In the Java class hierarchy, the root is the 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.
HTTPS HyperText Transfer Protocol
layered over the SSL protocol. IDL Interface Definition
Language. APIs written in the Java programming language that provide
standards-based interoperability and connectivity with CORBA (Common Object
Request Broker Architecture). identifier The name of an item in a
program written in the Java programming language. IIOP Internet Inter-ORB
Protocol. A protocol used for communication between CORBA object request
brokers. if A Java
keyword used to conduct a conditional test and execute a block of statements
if the test evaluates to true. impersonation An act whereby one entity
assumes the identity and privileges of another entity without restrictions
and without any indication visible to the recipients of the impersonator's
calls that delegation has taken place. Impersonation is a case of simple
delegation. implements A Java keyword included in
the class declaration to specify any interfaces that are implemented by the
current class. import A Java 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 programming language, an instance of a
class is created using the Any method that is invoked
with respect to an instance of a class. Also called simply a method. See also class method. 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. instanceof A two-argument Java keyword
that tests whether the runtime type of its first argument is assignment compatible
with its second argument. int A Java keyword used to
define a variable of type interface A Java 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. 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. 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. A module that alternately
decodes and executes every statement in some body of code. The Java
interpreter decodes and executes bytecode for the Java virtual machine1. See also compiler, runtime system. JAIN See: Java APIs for Integrated Networks (JAIN) JAR JAR (Java Archive) is a
platform-independent file format that aggregates many files into one.
Multiple applets written in the Java programming language, and their
requisite components (.class files, images, sounds and other resource files)
can be bundled in a JAR file and subsequently downloaded to a browser in a
single HTTP transaction. It also supports file compression and digital
signatures. Java A set of technologies for
creating and safely running software programs in both stand-alone and
networked environments. Java 2 Platform The
second generation of the Java platform. (The first generation was the JDK.)
Also see "Java Platform" and "Java Platform Editions". Java 2 Platform, Enterprise Edition (J2EE platform) See Java 2 Platform, Enterprise Edition, under Java
Platform Editions. Java 2 Platform, Micro Edition (J2ME platform) See Java 2 Platform, Micro Edition, under Java
Platform Editions. Java 2 Platform, Standard Edition (J2SE platform) See Java 2 Platform, Standard Edition, under Java
Platform Editions. Java 2 SDK, Standard Edition The Software Development
Kit (SDK) is development environment for building applications, applets, and
components using the Java programming language. This SDK provides a reference
implementation of the J2SE platform. Java APIs for
Integrated Networks (JAIN) enables the rapid
development of Next Generation telecom products and services on the Java
platform. Java Card API An ISO 7816-4 compliant
application environment focused on smart cards. Java Compatibility Kit (JCK) A test suite, a set of
tools, and other requirements used to certify a Java platform implementation
conformant both to the applicable Java platform specifications and to Java
Software reference implementations. Java Database Connectivity
(JDBC) An
industry standard for database-independent connectivity between the Java
platform and a wide range of databases. The JDBC provides a call-level API
for SQL-based database access. Java Development Kit (JDK) A
software development environment for writing applets and applications in the
Java programming language. Technically, the JDK is the correct name for all
versions of the Java platform from 1.0 to 1.1.x. Java Foundation Classes (JFC) An
extension that adds graphical user interface class libraries to the Abstract
Windowing Toolkit (AWT). Java IDL See Java Interface
Definition Language Java Interface Definition
Language (IDL) A set of Java APIs that
provide CORBA (Common Object Request Broker Architecture) interoperability
and connectivity capabilities for the J2EE platform. These capabilities
enable J2EE applications to invoke operations on remote network services
using the OMG IDL and IIOP. Java Media APIs A set of APIs that support
the integration of audio and video clips, 2D fonts, graphics, and images as
well as 3D models and telephony. Java Media Framework The core framework supports
clocks for synchronizing between different media (e.g., audio and video
output). The standard extension framework allows users to do full audio and
video streaming. Java Naming and Directory
Interface (JNDI) A set of APIs that assists
with the interfacing to multiple naming and directory services. A standard programming
interface for writing Java native methods and embedding the JVM into native
applications. The primary goal is binary compatibility of native method libraries
across all JVM implementations on a given platform. Java Platform Consists of class
libraries, a Java virtual machine (JVM) and class loader (which comprise the
runtime environment) and a compiler, debugger and other tools (which comprise
the development kit). Java Platform Editions A Java platform
"edition" is a definitive and agreed-upon version of the Java
platform that provides the functionality needed over a broad market segment. Java Remote Method
Invocation (RMI) A distributed object model
for Java program to Java program, in which the methods of remote objects
written in the Java programming language can be invoked from other Java
virtual machines1,
possibly on different hosts. Java Runtime Environment
(JRE) A subset of the Java
Development Kit (JDK) for end-users and developers who want to redistribute
the runtime environment alone. The Java runtime environment consists of the
Java virtual machine1,
the Java core classes, and supporting files. Java virtual machine1 A software "execution
engine" that safely and compatibly executes the byte codes in Java class
files on a microprocessor (whether in a computer or in another electronic
device). JavaBeans A portable,
platform-independent reusable component model. A component that conforms to
this model is called a bean. JavaCheck A tool for checking
compliance of applications and applets to a specification. JavaSafe A tool for tracking and
managing source file changes, written in Java. JavaScript A Web scripting language
that is used in both browsers and Web servers. Like all scripting languages,
it is used primarily to tie other components together or to accept user
input. JavaSpaces A technology that provides
distributed persistence and data exchange mechanisms for code in Java. JDBC See Java Database Connectivity. JDK Java Development Kit. A
software development environment for writing applets and application in Java
. JFC Jini Technology A set of Java APIs that may
be incorporated an optional package for any Java 2 Platform Edition. The Jini
APIs enable transparent networking of devices and services and eliminates the
need for system or network administration intervention by a user. JNDI See Java Naming and Directory Interface. JNI JRE Just-in-time (JIT) Compiler A compiler that converts
all of the bytecode into native machine code just as a Java program is run.
This results in run-time speed improvements over code that is interpreted by
a Java virtual machine. JVM See Java Virtual Machine (JVM). keyword Java sets aside words as
keywords - these words are reserved by the language itself and therefore are
not available as names for variables or methods. lexical Pertaining to how the
characters in source code are translated into tokens that the compiler can
understand. linker A module that builds an
executable, complete program from component machine code modules. The Java
linker creates a runnable program from compiled classes. See also compiler, interpreter, runtime system. 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. 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 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. 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. native A Java keyword that is used
in method declarations to specify that the method is not implemented in the
same Java source file, but rather in another language. new A Java keyword used to
create an instance of a class. null The null type has one
value, the null reference, represented by the literal null, which is formed
from ASCII characters. A null literal is always of the null type. 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. The
numbering system using 8 as its base, using the numerals 0-7 as its digits.
In programs written in the Java programming language, octal numbers must be
preceded with 0. See also hexadecimal. optional packages The set or sets of APIs in
a Java platform edition which are available with and may be supported in a
compatible implementation. ORB Object Request Broker. A
library than enables CORBA objects to locate and communicate with one another.
OS principal A principal native to the
operating system on which the Java platform is executing. OTS Object Transaction Service.
A definition of the interfaces that permit CORBA objects to participate in
transactions. overloading Using one identifier to
refer to multiple items in the same scope. In the Java programming language,
you can overload methods but not variables or operators. overriding Providing a different
implementation of a method in a subclass of the class that originally defined
the method. A group of types. Packages are
declared with the package keyword. In networking, any
functional unit in the same layer as another entity. persistence The protocol for
transferring the state of a bean between its instance variables and an
underlying database. pixel The picture element on a
display area, such as a monitor screen or printed page. Each pixel is
individually accessible. POA Portable Object Adapter. A
CORBA standard for building server-side applications that are portable across
heterogeneous ORBs. primary key An object that uniquely
identifies an entity bean within a home. A variable data type in
which the variable's value is of the appropriate size and format for its
type: a number, a character, or a boolean value. principal The identity assigned to an
entity as a result of authentication. private A Java 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. privilege A security attribute that
does not have the property of uniqueness and which may be shared by many
principals. An example of a privilege is a group. A virtual address space
containing one or more threads. property Characteristics of an object
that users can set, such as the color of a window. profiles A profile is a collection
of Java APIs that complements one or more Java 2 Platform Editions by adding
domain-specific capabilities. Profiles may also include other defined
profiles. A profile implementation requires a Java 2 Platform Edition to
create a complete development and deployment environment in a targeted
vertical market. Each profile is subject to an associated set of
compatibility requirements. protected A Java 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 keyword used in a
method or variable declaration. It signifies that the method or variable can
be accessed by elements residing in other classes. raster A two-dimensional
rectangular grid of pixels. realm See security policy domain.
Also, a string, passed as part of an HTTP request during basic
authentication, that defines a protection space. The protected resources on a
server can be partitioned into a set of protection spaces, each with its own
authentication scheme and/or authorization database. A variable data type in
which the variable's value is an address. return A Java keyword used to
finish the execution of a method. It can be followed by a value required by
the method definition. RMI See Java Remote Method Invocation. rollback The point in a transaction
when all updates to any databases involved in the transaction are reversed. root In a hierarchy of items,
the one item from which all other items are descended. The root item has
nothing above it in the hierarchy. See also hierarchy, class, package.
RPC Remote Procedure Call.
Executing what looks like a normal procedure call (or method invocation) by
sending network packets to some remote host. The software environment in
which programs compiled for the Java virtual machine1 can run. The runtime system includes
all the code necessary to load programs written in the Java programming
language, dynamically link native methods, manage memory, handle exceptions,
and an implementation of the Java virtual machine, which may be a Java
interpreter. SAX Simple API for XML. An
event-driven, serial-access mechanism for accessing XML documents. sandbox Comprises a number of
cooperating system components, ranging from security managers that execute as
part of the application, to security measures designed into the Java virtual
machine1 and the
language itself. The sandbox ensures that an untrusted, and possibly
malicious, application cannot gain access to system resources. scope A characteristic of an
identifier that determines where the identifier can be used. Most identifiers
in the Java 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.
security attributes A set of properties
associated with a principal. Security attributes can be associated with a
principal by an authentication protocol. security context An object that encapsulates
the shared state information regarding security between two entities. security policy domain A scope over which security
policies are defined and enforced by a security administrator. A security
policy domain has the following characteristics: security technology domain A scope over which the same
security mechanism is used to enforce a security policy. Multiple security
policy domains can exist within a single technology domain. serialization The encoding of objects,
and the objects reachable from them, into a stream of bytes and the
complementary reconstruction of the object graph from the stream. short A Java keyword used to
define a variable of type short.
In the Java language
specification, describes a floating point number with 32 bits of data. See
also double precision. SGML Standardized Generalized
Markup Language. An ISO/ANSI/ECMA standard that specifies a way to annotate
text documents with information about types of sections of a document. The Simple Object Access
Protocol (SOAP) uses a combination of XML-based data structuring and the
Hyper Text Transfer Protocol (HTTP) to define a standardized method for
invoking methods in objects distributed in diverse operating environments
across the Internet. SQL Structured Query Language.
The standardized relational database language for defining database objects
and manipulating data. static A Java 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. Another name for class variable. Another name for class method. stream A stream is simply a
byte-stream of data that is sent from a sender to a receiver. There are two
basic categories, so the java.io
package includes two abstract classes (InputStream and OutputStream). subarray An array that is inside
another array. A class that is derived
from a particular class, perhaps with one or more classes in between. See
also superclass, supertype. If type X extends or
implements type Y, then X is a subtype of Y. See also supertype. A class from which a
particular class is derived, perhaps with one or more classes in between. See
also subclass, subtype. super A Java keyword used to
access members of a class inherited by the class in which it appears. The supertypes of a type
are all the interfaces and classes that are extended or implemented by that
type. See also subtype, superclass. switch A Java 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. A collection of graphical
user interface (GUI) components that runs uniformly on any native platform
which supports the Java virtual machine*. Because they are written entirely in the Java programming
language, these components may provide functionality above and beyond that
provided by native-platform equivalents. (Contrast with AWT.) synchronized A keyword in the Java
programming language that, when applied to a method or code block, guarantees
that at most one thread at a time executes that code. 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. thin client A system that runs a very
light operating system with no local system administration and executes
applications delivered over the network. this A Java 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. 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. throw A Java
keyword that allows the user to throw an exception or any class that implements
the "throwable" interface. throws A Java 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. transaction An atomic unit of work that
modifies data. A transaction encloses one or more program statements, all of
which either complete or roll back. Transactions enable multiple users to
access the same data concurrently. transaction isolation level The degree to which the
intermediate state of the data being modified by a transaction is visible to
other concurrent transactions and data being modified by other transactions
is visible to it. transaction manager Provides the services and
management functions required to support transaction demarcation,
transactional resource management, synchronization, and transaction context
propagation. transient A keyword in the Java
programming language that indicates that a field is not part of the
serialized form of an object. When an object is serialized, the values of its
transient fields are not included in the serial representation, while the
values of its non-transient fields are included. try A Java
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. A class or interface. A 16-bit character set
defined by ISO 10646. See also ASCII.
All source code in the Java programming environment is written in Unicode. URI Uniform Resource
Identifier. A compact string of characters for identifying an abstract or
physical resource. A URI is either a URL or a URN. URLs and URNs are concrete
entities that actually exist; A URI is an abstract superclass. 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. URN Uniform Resource Name. A
unique identifier that identifies an entity, but doesn't tell where it is
located. A system can use a URN to look up an entity locally before trying to
find it on the Web. It also allows the Web location to change, while still
allowing the entity to be found. 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
virtual machine consists of a bytecode instruction set, a set of registers, a
stack, a garbage-collected heap, and an area for storing methods. void A Java keyword used in
method declarations to specify that the method does not return any value. void can also be used as a nonfunctional statement. volatile A Java keyword used in
variable declarations that specifies that the variable is modified
asynchronously by concurrently running threads. Web server Software that provides
services to access the Internet, an intranet, or an extranet. A Web server
hosts Web sites, provides support for HTTP and other protocols, and executes
server-side programs (such as CGI scripts or servlets) that perform certain
functions. while A Java 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. wrapper An object that encapsulates
and delegates to another object to alter its interface or behavior in some
way. WWW World Wide Web. The web of
systems and the data in them that is the Internet. See also Internet. XML Extensible Markup Language.
A markup language that allows you to define the tags (markup) needed to
identify the data and text in XML documents.
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