j2me faqs and j2se faqs

2007-05-31T13:17:00.001-07:00

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j2me faqs

2007-05-29T12:31:00.000-07:00

J2ME Interview Questions And Answers [J2ME Frequently Asked Questions ,J2ME FAQ ]

What is J2ME ?
Java 2, Micro Edition is a group of specifications and technologies that pertain to Java on small devices. The J2ME moniker covers a wide range of devices, from pagers and mobile telephones through set-top boxes and car navigation systems. The J2ME world is divided into configurations and profiles, specifications that describe a Java environment for a specific class of device.

What is J2ME WTK ?
The J2ME Wireless Toolkit is a set of tools that provides developers with an emulation environment, documentation and examples for developing Java applications for small devices. The J2ME WTK is based on the Connected Limited Device Configuration (CLDC) and Mobile Information Device Profile (MIDP) reference implementations, and can be tightly integrated with Forte for Java

What is 802.11 ?
802.11 is a group of specifications for wireless networks developed by the Institute of Electrical and Electronics Engineers (IEEE). 802.11 uses the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.

What is API ?
An Application Programming Interface (API) is a set of classes that you can use in your own application. Sometimes called libraries or modules, APIs enable you to write an application without reinventing common pieces of code. For example, a networking API is something your application can use to make network connections, without your ever having to understand the underlying code. 5. What is AMPS

Advanced Mobile Phone Service (AMPS) is a first-generation analog, circuit-switched cellular phone network. Originally operating in the 800 MHz band, service was later expanded to include transmissions in the 1900 MHz band, the VHF range in which most wireless carriers operate. Because AMPS uses analog signals, it cannot transmit digital signals and cannot transport data packets without assistance from newer technologies such as TDMA and CDMA.

What is CDC ?

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The Connected Device Configuration (CDC) is a specification for a J2ME configuration. Conceptually, CDC deals with devices with more memory and processing power than CLDC; it is for devices with an always-on network connection and a minimum of 2 MB of memory available for the Java system.

What is CDMA ?
Code-Division Multiple Access (CDMA) is a cellular technology widely used in North America. There are currently three CDMA standards: CDMA One, CDMA2000 and W-CDMA. CDMA technology uses UHF 800Mhz-1.9Ghz frequencies and bandwidth ranges from 115Kbs to 2Mbps.

What is CDMA One ?
Also know as IS-95, CDMA One is a 2nd generation wireless technology. Supports speeds from 14.4Kbps to 115K bps.

What is CDMA2000 ?
Also known as IS-136, CDMA2000 is a 3rd generation wireless technology. Supports speeds ranging from 144Kbps to 2Mbps.

What is CDPD ?
Developed by Nortel Networks, Cellular Digital Packet Data (CDPD) is an open standard for supporting wireless Internet access from cellular devices. CDPD also supports Multicast, which allows content providers to efficiently broadcast information to many devices at the same time.

What is cHTML ?
Compact HTML (cHTML) is a subset of HTML which is designed for small devices. The major features of HTML that are excluded from cHTML are: JPEG image, Table, Image map, Multiple character fonts and styles, Background color and image, Frame and Style sheet.

What is CLDC ?
The Connected, Limited Device Configuration (CLDC) is a specification for a J2ME configuration. The CLDC is for devices with less than 512 KB or RAM available for the Java system and an intermittent (limited) network connection. It specifies a stripped-down Java virtual machine1 called the KVM as well as several APIs for fundamental application services. Three packages are minimalist versions of the J2SE java.lang, java.io, and java.util packages. A fourth package, javax.microedition.io, implements the Generic Connection Framework, a generalized API for making network connections.

What is configuration ?
In J2ME, a configuration defines the minimum Java runtime environment for a family of devices: the combination of a Java virtual machine (either the standard J2SE virtual machine or a much more limited version called the CLDC VM) and a core set of APIs. CDC and CLDC are configurations. See also profile, optional package.

What is CVM ?
The Compact Virtual Machine (CVM) is an optimized Java virtual machine1 (JVM) that is used by the CDC.

What is Deck ?
A deck is a collection of one or more WML cards that can be downloaded, to a mobile phone, as a single entity.

What is EDGE ?
Enhanced Data GSM Environment (EDGE) is a new, faster version of GSM. EDGE is designed to support transfer rates up to 384Kbps and enable the delivery of video and other high-bandwidth applications. EDGE is the result of a joint effort between TDMA operators, vendors and carriers and the GSM Alliance.

What is ETSI ?
The European Telecommunications Standards Institute (ETSI) is a non-profit organization that establishes telecommunications standards for Europe.

What is FDMA ?
Frequency-division multiple-access (FDMA) is a mechanism for sharing a radio frequency band among multiple users by dividing it into a number of smaller bands.

What is Foundation Profile ?
The Foundation Profile is a J2ME profile specification that builds on CDC. It adds additional classes and interfaces to the CDC APIs but does not go so far as to specify user interface APIs, persistent storage, or application life cycle. Other J2ME profiles build on the CDC/Foundation combination: for example, the Personal Profile and the RMI Profile both build on the Foundation Profile.

What is Generic Connection Framework ?
The Generic Connection Framework (GCF) makes it easy for wireless devices to make network connections. It is part of CLDC and CDC and resides in the javax.microedition.io package.

What is GPRS ?
The General Packet Radio System (GPRS) is the next generation of GSM. It will be the basis of 3G networks in Europe and elsewhere.

What is GSM ?
The Global System for Mobile Communications (GSM) is a wireless network system that is widely used in Europe, Asia, and Australia. GSM is used at three different frequencies: GSM900 and GSM1800 are used in Europe, Asia, and Australia, while GSM1900 is deployed in North America and other parts of the world.

What is HLR ?
The Home Location Register (HLR) is a database for permanent storage of subscriber data and service profiles.

What is HTTPS ?
Hyper Text Transfer Protocol Secure sockets (HTTPS) is a protocol for transmission of encrypted hypertext over Secure Sockets Layer.

What is i-appli ?
Sometimes called "Java for i-mode", i-appli is a Java environment based on CLDC. It is used on handsets in NTT DoCoMo's i-mode service. While i-appli is similar to MIDP, it was developed before the MIDP specification was finished and the two APIs are incompatible.

What is IDE ?
An Integrated Development Environment (IDE) provides a programming environment as a single application. IDEs typically bundle a compiler, debugger, and GUI builder tog ether. Forte for Java is Sun's Java IDE.

What is iDEN ?
The Integrated Dispatch Enhanced Network (iDEN) is a wireless network system developed by Motorola. Various carriers support iDEN networks around the world: Nextel is one of the largest carriers, with networks covering North and South America.

What is i-mode ?
A standard used by Japanese wireless devices to access cHTML (compact HTML) Web sites and display animated GIFs and other multimedia content.

What is 3G ?
Third generation (3G) wireless networks will offer faster data transfer rates than current networks. The first generation of wireless (1G) was analog cellular. The second generation (2G) is digital cellular, featuring integrated voice and data communications. So-called 2.5G networks offer incremental speed increases. 3G networks will offer dramatically improved data transfer rates, enabling new wireless applications such as streaming media.

What is 3GPP ?
The 3rd Generation Partnership Project (3GPP) is a global collaboration between 6 partners: ARIB, CWTS, ETSI, T1, TTA, and TTC. The group aims to develop a globally accepted 3rd-generation mobile system based on GSM.

What is Java Card ?
The Java Card specification allows Java technology to run on smart cards and other small devices. The Java Card API is compatible with formal international standards, such as, ISO7816, and industry-specific standards, such as, Europay/Master Card/Visa (EMV).

What is JavaHQ ?
JavaHQ is the Java platform control center on your Palm OS device.

What is JCP ?
The Java Community Process (JCP) an open organization of international Java developers and licensees who develop and revise Java technology specifications, reference implementations, and technology compatibility kits through a formal process.

What is JDBC for CDC/FP ?
The JDBC Optional Package for CDC/Foundation Profile (JDBCOP for CDC/FP) is an API that enables mobile Java applications to communicate with relational database servers using a subset of J2SE's Java Database Connectivity. This optional package is a strict subset of JDBC 3.0 that excludes some of JDBC's advanced and server-oriented features, such as pooled connections and array types. It's meant for use with the Foundation Profile or its supersets.

What is JSR
Java Specification Request (JSR) is the actual description of proposed and final specifications for the Java platform. JSRs are reviewed by the JCP and the public before a final release of a specification is made.

What is KittyHawk
KittyHawk is a set of APIs used by LG Telecom on its IBook and p520 devices. KittyHawk is based on CLDC. It is conceptually similar to MIDP but the two APIs are incompatible.

What is KJava
KJava is an outdated term for J2ME. It comes from an early package of Java software for PalmOS, released at the 2000 JavaOne show. The classes for that release were packaged in the com.sun.kjava package.

What is kSOAP
kSOAP is a SOAP API suitable for the J2ME, based on kXML.

What is kXML
The kXML project provides a small footprint XML parser that can be used with J2ME.

What is KVM
The KVM is a compact Java virtual machine (JVM) that is designed for small devices. It supports a subset of the features of the JVM. For example, the KVM does not support floating-point operations and object finalization. The CLDC specifies use of the KVM. According to folklore, the 'K' in KVM stands for kilobyte, signifying that the KVM runs in kilobytes of memory as opposed to megabytes.

What is LAN
A Local Area Network (LAN) is a group of devices connected with various communications technologies in a small geographic area. Ethernet is the most widely-used LAN technology. Communication on a LAN can either be with Peer-to-Peer devices or Client-Server devices.

What is LCDUI
LCDUI is a shorthand way of referring to the MIDP user interface APIs, contained in the javax.microedition.lcdui package. Strictly speaking, LCDUI stands for Liquid Crystal Display User Interface. It's a user interface toolkit for small device screens which are commonly LCD screens.

What is MExE
The Mobile Execution Environment (MExE) is a specification created by the 3GPP which details an applicatio n environment for next generation mobile devices. MExE consists of a variety of technologies including WAP, J2ME, CLDC and MIDP.

What is MIDlet
A MIDlet is an application written for MIDP. MIDlet applications are subclasses of the javax.microedition.midlet.MIDlet class that is defined by MIDP.

What is MIDlet suite
MIDlets are packaged and distributed as MIDlet suites. A MIDlet suite can contain one or more MIDlets. The MIDlet suite consists of two files, an application descriptor file with a .jad extension and an archive file with a .jar file. The descriptor lists the archive file name, the names and class names for each MIDlet in the suite, and other information. The archive file contains the MIDlet classes and resource files.

What is MIDP
The Mobile Information Device Profile (MIDP) is a specification for a J2ME profile. It is layered on top of CLDC and adds APIs for application life cycle, user interface, networking, and persistent storage.

What is MIDP-NG
The Next Generation MIDP specification is currently under development by the Java Community Process. Planned improvements include XML parsing and cryptographic support.

What is Mobitex
Mobitex is a packet-switched, narrowband PCS network, designed for wide-area wireless data communications. It was developed in 1984 by Eritel, an Ericsson subsidiary, a nd there are now over 30 Mobitex networks in operation worldwide.

What is Modulation ?
Modulation is the method by which a high-frequency digital signal is grafted onto a lower-frequency analog wave, so that digital packets are able to ride piggyback on the analog airwave.

What is MSC ?
A Mobile Switching Center (MSC) is a unit within a cellular phone network that automatically coordinates and switches calls in a given cell. It monitors each caller's signal strength, and when a signal begins to fade, it hands off the call to another MSC that's better positioned to manage the call.

What is Obfuscation
Obfuscation is a technique used to complicate code. Obfuscation makes code harder to understand when it is de-compiled, but it typically has no affect on the functionality of the code. Obfuscation programs can be used to protect Java programs by making them harder to reverse-engineer.

What is optional package
An optional package is a set of J2ME APIs providing services in a specific area, such as database access or multimedia. Unlike a profile, it does not define a complete application environment, but rather is used in conjunction with a configuration or a profile. It extends the runtime environment to support device capabilities that are not universal enough to be defined as part of a profile or that need to be shared by different profiles. J2ME RMI and the Mobile Media RMI are examples of optional packages.

What is OTA
Over The Air (OTA) refers to any wireless networking technology.

What is PCS
Personal Communications Service (PCS) is a suite of second-generation, digitally modulated mobile-communications interfaces that includes TDMA, CDMA, and GSM. PCS serves as an umbrella term for second-generation wireless technologies operating in the 1900MHz range

What is PDAP
The Personal Digital Assistant Profile (PDAP) is a J2ME profile specification designed for small platforms such as PalmOS devices. You can think of PDAs as being larger than mobile phones but smaller than set-top boxes. PDAP is built on top of CLDC and will specify user interface and persistent storage APIs. PDAP is currently being developed using the Java Community Process (JCP).

What is PDC
Personal Digital Cellular (PDC) is a Japanese standard for wireless communications.

What is PDCP
Parallel and Distributed Computing Practices (PDCP) are often used to describe computer systems that are spread over many devices on a network (wired or wireless) where many nodes process data simultaneously.

What is Personal Profile
The Personal Profile is a J2ME profile specification. Layered on the Foundation Profile and CDC, the Personal Profile will be the next generation of PersonalJava technology. The specification is currently in development under the Java Community Process (JCP).

What is PersonalJava
PersonalJava is a Java environment based on the Java virtual machine1 (JVM) and a set of APIs similar to a JDK 1.1 environment. It includes the Touchable Look and Feel (also called Truffle), a graphic toolkit that is optimized for consumer devices with a touch sensitive screen. PersonalJava will be included in J2ME in the upcoming Personal Profile, which is built on CDC.

What is PNG
Portable Network Graphics (PNG) is an image format offering lossless compression and storage flexibility. The MIDP specification requires implementations to recognize certain types of PNG images.

What is POSE
Palm OS Emulator (POSE).

What is PRC
Palm Resource Code (PRC) is the file format for Palm OS applications.

What is preverification
Due to memory and processing power available on a device, the verification process of classes are split into two processes. The first process is the preverification which is off-device and done using the preverify tool. The second process is verification which is done on-device.

What is profile
A profile is a set of APIs added to a configuration to support specific uses of a mobile device. Along with its underlying configuration, a profile defines a complete, and usually self-contained, general-purpose application environment. Profiles often, but not always, define APIs for user interface and persistence; the MIDP profile, based on the CLDC configuration, fits this pattern. Profiles may be supersets or subsets of other profiles; the Personal Basis Profile is a subset of the Personal Profile and a superset of the Foundation Profile. See also configuration, optional package.

What is Provisioning ?
In telecommunications terms, provisioning means to provide telecommunications services to a user. This includes providing all necessary hardware, software, and wiring or transmission devices.

What is PSTN ?
The public service telephone network (PSTN) is the traditional, land-line based system for exchanging phone calls.

What is RMI
Remote method invocation (RMI) is a feature of J2SE that enables Java objects running in one virtual machine to invoke methods of Java objects running in another virtual machine, seamlessly.

What is RMI OP
The RMI Optional Package (RMI OP) is a subset of J2SE 1.3's RMI functionality used in CDC-based profiles that incorporate the Foundation Profile, such as the Personal Basis Profile and the Personal Profile. The RMIOP cannot be used with CLDC-based profiles because they lack object serialization and other important features found only in CDC-based profiles. RMIOP supports most of the J2SE RMI functionality, including the Java Remote Method Protocol, marshalled objects, distributed garbage collection, registry-based object lookup, and network class loading, but not HTTP tunneling or the Java 1.1 stub protocol.

What is RMI Profile
The RMI Profile is a J2ME profile specification designed to support Java's Remote Method Invocation (RMI) distributed object system. Devices implementing the RMI Profile will be able to interoperate via RMI with other Java devices, including Java 2, Standard Edition. The RMI Profile is based on the Foundation Profile, which in turn is based on CDC.

What is RMS
The Record Management System (RMS) is a simple record-oriented database that allows a MIDlet to persistently store information and retrieve it later. Different MIDlets can also use the RMS to share data.

What is SDK
A Software Development Kit (SDK) is a set of tools used to develop applications for a particular platform. An SDK typically contains a compiler, linker, and debugger. It may also contain libraries and documentation for APIs.

What is SIM
A Subscriber Identity Module (SIM) is a stripped-down smart card containing information about the identity of a cell-phone subscriber, and subscriber authentication and service information. Because the SIM uniquely identifies the subscriber and is portable among handsets, the user can move it from one kind of phone to another, facilitating international roaming.

What is SMS
Short Message Service (SMS) is a point-to-point service similar to paging for sending text messages of up to 160 characters to mobile phones.

What is SOAP
The Simple Object Access Protocol (SOAP) is an XML- based protocol that allows objects of any type to communicated in a distributed environment. SOAP is used in developing Web Services.

What is SSL
Secure Sockets Layer (SSL) is a socket protocol that encrypts data sent over the network and provides authentication for the socket endpoints.

What is T9
T9 is a text input method for mobile phones and other small devices. It replaces the "multi-tap" input method by guessing the word that you are trying to enter. T9 may be embedded in a device by the manufacturer. Note that even if the device supports T9, the Java implementation may or may not use it. Check your documentation for details.

What is TDMA
Time Division Multiple Access (TDMA) is a second-generation modulation standard using bandwidth allocated in the 800 MHz, 900 MHz, and 1900MHz ranges.

What is Telematics
Telematics is a location-based service that routes event notification and control data over wireless networks to and from mobile devices installed in automobiles. Telematics makes use of GPS technology to track vehicle latitude and longitude, and displays maps in LED consoles mounted in dashboards. It connects to remote processing centers that turn provide server-side Internet and voice services, as well as access to database resources.

What is Tomcat ?
Tomcat is a reference implementation of the Java servlet and JavaServer Pages (JSP) specifications. It is intended as a platform for developing and testing servlets.

What is UDDI ?
Universal Description, Discovery, and Integration (UDDI) is an XML-based standard for describing, publishing, and finding Web services. UDDI is a specification for a distributed registry of Web services.

What is UMTS
Developed by Nortel Networks, Universal Mobile Telecommunications Service (UMTS) is a standard that will provide cellular users a consistent set of technologies no matter where they are located worldwide. UMTS utilizes W-CDMA technology.

What is VLR
The Visitor Location Register (VLR) is a database that contains temporary information about subscribers.

What is WAE
The Wireless Application Environment (WAE) provides a application framework for small devices. WAE leverages other technologies such as WAP, WTP, and WSP.

What is WAP
Wireless Application Protocol (WAP) is a protocol for transmitting data between servers and clients (usually small wireless devices like mobile phones). WAP is analogous to HTTP in the World Wide Web. Many mobile phones include WAP browser software to allow users access to Internet WAP sites.

What is WAP Gateway
A WAP Gateway acts as a bridge allowing WAP devices to communicate with other networks (namely the Internet).

What is W-CDMA
Wideband Code-Division Multiple Access (W-CDMA), also known as IMT-2000, is a 3rd generation wireless technology. Supports speeds up to 384Kbps on a wide-area network, or 2Mbps locally.

What is WDP
Wireless Datagram Protocol (WDP) works as the transport layer of WAP. WDP processes datagrams from upper layers to formats required by different physical datapaths, bearers, that may be for example GSM SMS or CDMA Packet Data. WDP is adapted to the bearers available in the device so upper layers don't need to care about the physical level.

What is WMA
The Wireless Messaging API (WMA) is a set of classes for sending and receiving Short Message Service messages. See also SMS.

What is WML
The Wireless Markup Language (WML) is a simple language used to create applications for small wireless devices like mobile phones. WML is analogous to HTML in the World Wide Web.

What is WMLScript
WMLScript is a subset of the JavaScript scripting language designed as part of the WAP standard to provide a convenient mechanism to access mobile phone's peripheral functions.

What is WSP
Wireless Session Protocol (WSP) implements session services of WAP. Sessions can be connection-oriented and connectionless and they may be suspended and resumed at will.

What is WTLS
Wireless Transport Layer Security protocal (WTLS) does all cryptography oriented features of WAP. WTLS handles encryption/decryption, user authentication and data integrity. WTLS is based on the fixed network Transport Layer Security protocal (TLS), formerly known as Secure Sockets Layer (SSL).

What is WTP
Wireless Transaction Protocol (WTP) is WAP's transaction protocol that works between the session protocol WSP and security protocol WTLS. WTP chops data packets into lower level datagrams and concatenates received datagrams into useful data. WTP also keeps track of received and sent packets and does re-transmissions and acknowledgment sending when needed.

j2se faqs

2007-05-29T12:22:00.000-07:00

J2SE Interview Questions And Answers [J2SE Frequently Asked Questions ,J2SE FAQ ]

What is 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.

What is 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.

What is abstract method ?
A method that has no implementation.

What is Abstract Window Toolkit (AWT) ?
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.

What is access control ?
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.

What is ACID ?
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

What is actual parameter list ?
The arguments specified in a particular method call. See also formal parameter list.

What is API ?

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Application Programming Interface. The specification of how a programmer writing an application accesses the behavior and state of classes and objects.

What is 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.

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

What is atomic ?
Refers to an operation that is never interrupted or left in an incomplete state under any circumstance.

What is authentication ?
The process by which an entity proves to another entity that it is acting on behalf of a specific identity.

What is autoboxing ?
Automatic conversion between reference and primitive types.

What is 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.

What is binary operator ?
An operator that has two arguments.

What is 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 (~).

What is block ?
In the Java programming language, any code between matching braces. Example: { x = 1; }.

What is 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.

What is 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.

What is bytecode ?
Machine-independent code generated by the Java compiler and executed by the Java interpreter.

What is case ?
A Java keyword that defines a group of statements to begin executing if a value specified matches the value defined by a preceding switch keyword.

What is casting ?
Explicit conversion from one data type to another.

What is 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 try block.

What is "abstract schema" ?
The part of an entity bean's deployment descriptor that defines the bean's persistent fields and relationships.

What is "abstract schema name" ?
A logical name that is referenced in EJB QL queries.

What is "access control" ?
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.

What is "ACID" ?
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

What is "activation" ?

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The process of transferring an enterprise bean from secondary storage to memory. (See passivation.)

What is "anonymous access" ?
Accessing a resource without authentication.

What is class ?
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 Object.

What is class method ?
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.

What is class variable ?
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.

What is 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.

What is client ?
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.

What is CODEBASE ?
Works together with the code attribute in the tag to give a complete specification of where to find the main applet class file: code specifies the name of the file, and codebase specifies the URL of the directory containing the file.

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

What is commit ?
The point in a transaction when all updates to any resources involved in the transaction are made permanent.

What is 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.

What is compiler ?
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.

What is compositing ?
The process of superimposing one image on another to create a single image.

What is 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 new keyword.
What is const ?
A reserved Java keyword not used by current versions of the Java programming language.
What is continue ?
A Java 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.

What is 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.

What is CORBA ?
Common Object Request Broker Architecture. A language independent, distributed object model specified by the Object Management Group (OMG).

What is 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. .

What is core packages ?
The required set of APIs in a Java platform edition which must be supported in any and all compatible implementations.

What is credentials ?
The information describing the security attributes of a principal. Credentials can be acquired only through authentication or delegation.

What is 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.

What is 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.
What is default ?
A Java keyword optionally used after all case conditions in a switch statement. If all case conditions are not matched by the value of the switch variable, the default keyword will be executed.

What is definition ?
A declaration that reserves storage (for data) or provides implementation (for methods). See also declaration.

What is delegation ?
An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.
What is deprecation ?
Refers to a class, interface, constructor, method or field that is no longer recommended, and may cease to exist in a future version.
What is derived from ?
Class X is "derived from" class Y if class X extends class Y. See also subclass, superclass.

What is distributed ?
Running in more than one address space.

What is 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).

What is 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 while keyword.

What is 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.

What is double ?
A Java keyword used to define a variable of type double.

What is double precision ?
In the Java programming language specification, describes a floating point number that holds 64 bits of data. See also single precision.

What is DTD ?
Document Type Definition. A description of the structure and properties of a class of XML files.

What is else ?
A Java keyword used to execute a block of statements in the case that the test condition with the if keyword evaluates to false.

What is Embedded Java 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.

What is 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.

What is enum ?
A Java keyword used to declare an enumerated type.

What is enumerated type ?
A type whose legal values consist of a fixed set of constants.

What is 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.

What is 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.

What is executable content ?
An application that runs from within an HTML file. See also applet.

What is 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.

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

What is 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.

What is 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 try keyword.

What is float ?
A Java keyword used to define a floating point number variable.

What is 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.

What is 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.

What is formal parameter list ?
The parameters specified in the definition of a particular method. See also actual parameter list.

What is 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.

What is 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.

What is goto ?
This is a reserved Java keyword. However, it is not used by current versions of the Java programming language.

What is 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.

What is hexadecimal ?
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.
What is group ?
A collection of principals within a given security policy domain.

What is hierarchy ?
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 Object class.

What is 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.

What is HTTP ?
Hypertext Transfer Protocol. The Internet protocol, based on TCP/IP, used to fetch hypertext objects from remote hosts. See also TCP/IP.

What is HTTPS ?
Hypertext Transfer Protocol layered over the SSL protocol.

What is 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).

What is identifier ?
The name of an item in a program written in the Java programming language.

What is IIOP ?
Internet Inter-ORB Protocol. A protocol used for communication between CORBA object request brokers.

What is if ?
A Java keyword used to conduct a conditional test and execute a block of statements if the test evaluates to true.

What is 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.

What is implements ?
A Java keyword included in the class declaration to specify any interfaces that are implemented by the current class.

What is 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.

What is inheritance ?
The concept of classes automatically containing the variables and methods defined in their super types. See also super class, subclass.

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

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

What is 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.

What is instanceof ?
A two-argument Java keyword that tests whether the runtime type of its first argument is assignment compatible with its second argument.
What is int ?
A Java keyword used to define a variable of type integer.

What is 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.

What is 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.

What is 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.

What is interpreter ?
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.

What is JAIN ?
See: Java APIs for Integrated Networks (JAIN)

What is 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.

What is Java ?
A set of technologies for creating and safely running software programs in both stand-alone and networked environments.

What is Java 2 Platform ?
The second generation of the Java platform. (The first generation was the JDK.) Also see "Java Platform" and "Java Platform Editions".

What is 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.

What is Java APIs for Integrated Networks (JAIN) ?
enables the rapid development of Next Generation telecom products and services on the Java platform.

What is Java Card API ?
An ISO 7816-4 compliant application environment focused on smart cards.

What is 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.

What is 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.

What is 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.
What is Java Foundation Classes (JFC) ?
An extension that adds graphical user interface class libraries to the Abstract Windowing Toolkit (AWT)
What is Java IDL ?
Java Interface Definition Language

What is 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.

What is 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.

What is 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.

What is Java Naming and Directory Interface (JNDI) ?
A set of APIs that assists with the interfacing to multiple naming and directory services.

What is Java Native Interface ?
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.

What is 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). In addition, the runtime platform is subject to a set of compatibility requirements to ensure consistent and compatible implementations. Implementations that meet the compatibility requirements may qualify for Sun's targeted compatibility brands. Java 2 is the current generation of the Java Platform.

What is 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. An edition is comprised of two kinds of API sets: (i) "core packages," which are essential to all implementations of a given platform edition, and (ii) "optional packages," which are available for a given platform edition and which may be supported in a compatible implementation.

There are 3 distinct editions of the Java Platform:

* Java 2 Platform, Enterprise Edition:
The edition of the Java platform that is targeted at enterprises to enable development, deployment, and management of multi-tier server-centric applications.
* Java 2 Platform, Micro Edition:
The edition of the Java platform that is targeted at small, standalone or connectable consumer and embedded devices to enable development, deployment, and management of applications that can scale from smart cards through mobile devices and set-top boxes to conventional computing devices.
* Java 2 Platform, Standard Edition:
The edition of the Java platform that enables development, deployment, and management of cross-platform, general-purpose applications.

What is 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.

What is 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.

What is Java virtual machine ?
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).

What is JavaBeans ?
A portable, platform-independent reusable component model. A component that conforms to this model is called a bean.

What is JavaCheck ?
A tool for checking compliance of applications and applets to a specification.
What is JavaSafe ?
A tool for tracking and managing source file changes, written in Java.

What is 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.

What is JavaSpaces ?
A technology that provides distributed persistence and data exchange mechanisms for code in Java.

What is JDBC ?
Java Database Connectivity.

What is JDK ?
Java Development Kit. A software development environment for writing applets and application in Java .

What is JFC ?
Java Foundation Classes.

What is 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. The Jini technology is currently an optional package available on all Java platform editions.

What is JNDI ?
Java Naming and Directory Interface.

What is JNI ?
Java Native Interface.

What is JRE ?
Java Runtime Environment

What is 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.

What is JVM ?
Java Virtual Machine (JVM).

What is 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.

What is lexical ?
Pertaining to how the characters in source code are translated into tokens that the compiler can understand.

What is 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.

What is 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.

What is 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.

What is long ?
A Java keyword used to define a variable of type long.
What is member ?
A field or method of a class. Unless specified otherwise, a member is not static.

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

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

What is 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.

What is new ?
A Java keyword used to create an instance of a class.

What is 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.

What is 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.

What is object-oriented design ?
A software design method that models the characteristics of abstract or real objects using classes and objects.

What is octal What is object-oriented design ?
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.

What is 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. Over time, optional packages may become required in an edition as the marketplace requires them.

What is ORB ?
Object Request Broker. A library than enables CORBA objects to locate and communicate with one another.

What is OS principal ?
A principal native to the operating system on which the Java platform is executing.

What is OTS ?
Object Transaction Service. A definition of the interfaces that permit CORBA objects to participate in transactions.

What is 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.

What is overriding ?
Providing a different implementation of a method in a subclass of the class that originally defined the method.

What is package ?
A group of types. Packages are declared with the package keyword.

What is peer ?
In networking, any functional unit in the same layer as another entity.

What is persistence ?
The protocol for transferring the state of a bean between its instance variables and an underlying database.
What is pixel ?
The picture element on a display area, such as a monitor screen or printed page. Each pixel is individually accessible.

What is POA ?
Portable Object Adapter. A CORBA standard for building server-side applications that are portable across heterogeneous ORBs.

What is primary key ?
An object that uniquely identifies an entity bean within a home

What is primitive type ?
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.

What is principal ?
The identity assigned to an entity as a result of authentication.

What is 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.

What is 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.

What is process ?
A virtual address space containing one or more threads.

What is property ?
Characteristics of an object that users can set, such as the color of a window.

What is 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. Profiles may be usable on one or more editions.

Some examples of profiles within the Java 2 Platform, Micro Edition are:

* Personal Profile- for non-PC products that need to display Web-compatible Java-based content
* Java Card - for secure smart cards and other severely memory-constrained devices.

What is 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.

What is 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.

What is raster ?
A two-dimensional rectangular grid of pixels.

What is 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

What is realm ?
A variable data type in which the variable's value is an address.

What is return ?
A Java keyword used to finish the execution of a method. It can be followed by a value required by the method definition.
What is RMI ?
See Java Remote Method Invocation.

What is rollback ?
The point in a transaction when all updates to any databases involved in the transaction are reversed.

What is 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.

What is RPC ?
Remote Procedure Call. Executing what looks like a normal procedure call (or method invocation) by sending network packets to some remote host.

What is runtime system ?
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.

What is SAX ?
Simple API for XML. An event-driven, serial-access mechanism for accessing XML documents.

What is 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.

What is 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.

What is Secure Socket Layer (SSL) ?
A protocol that allows communication between a Web browser and a server to be encrypted for privacy.

What is security attributes ?
A set of properties associated with a principal. Security attributes can be associated with a principal by an authentication protocol.

What is security context ?
An object that encapsulates the shared state information regarding security between two entities.

What is 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:
It has a collection of users (or principals).
It uses a well defined authentication protocol(s) for authenticating users (or principals).
It may have groups to simplify setting of security policies.

What is 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.

What is 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.

What is short ?
A Java keyword used to define a variable of type short.

What is single precision ?
In the Java language specification, describes a floating point number with 32 bits of data. See also double precision.
What is 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.

What is SOAP ?
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.

What is SQL ?
Structured Query Language. The standardized relational database language for defining database objects and manipulating data.

What is 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.

What is static field ?
Another name for class variable.

What is static method ?
Another name for class method.

What is 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).

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

What is subtype ?
If type X extends or implements type Y, then X is a subtype of Y. See also supertype.

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

What is super ?
A Java keyword used to access members of a class inherited by the class in which it appears.

What is supertype ?
The supertypes of a type are all the interfaces and classes that are extended or implemented by that type. See also subtype, superclass.

What is 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.

What is Swing ?
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.)

What is 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.

What is 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.
What is 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.

What is thin client ?
A system that runs a very light operating system with no local system administration and executes applications delivered over the network.

What is '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.

What is 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.

What is throw ?
A Java keyword that allows the user to throw an exception or any class that implements the "throwable" interface.

What is 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.

What is 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.

What is 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.

What is transaction manager ?
Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization, and transaction context propagation.

What is 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.

What is 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.

What is type ?
A class or interface.

What is Unicode ?
A 16-bit character set defined by ISO 10646. See also ASCII. All source code in the Java programming environment is written in Unicode.

What is 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.

What is 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.
What is 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.

What is 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.

What is 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 byte code instruction set, a set of registers, a stack, a garbage-collected heap, and an area for storing methods.

What is 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.

What is volatile ?
A Java keyword used in variable declarations that specifies that the variable is modified asynchronously by concurrently running threads.

What is 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.

What is 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.

What is 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.

What is wrapper ?
An object that encapsulates and delegates to another object to alter its interface or behavior in some way.

What is 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.

What is ACID ?
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

What is Embedded Java 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.

What is class method ?
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.

What is class variable ?
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.

What is 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 new keyword.

What is core packages ?
The required set of APIs in a Java platform edition which must be supported in any and all compatible implementations.