J2ME Interview Questions with Answers Page I

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1. 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.

2. 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

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. What is CDMA2000

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

11. 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.

12. What is CDC

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.

13. What is CDMA One

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

14. 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.

15. 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.

16. 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.

17. What is CVM

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

18. 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.

19. 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.

20. What is ETSI

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

21. 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.

22. 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.

23. What is kXML

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

24. 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.

25. 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.