J2ME Interview Questions
What is RMS ?
What is RMI Profile ?
What is PNG ?
What is Personal Profile ?
What is optional package ?
What is MIDlet ?
What is KVM ?
What is J2ME WTK ?
What is CLDC ?
What is CDC ?
What is the Generic Connection Framework ?
What is the current version of the MIDP specification ?
What are the minimum fields that must be present in a MIDlet suite's manifest ?
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.
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 inter operate 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.
Portable Network Graphics (PNG) is an image format offering loss less compression and storage flexibility. The MIDP specification requires implementations to recognize certain types of PNG images
The Personal Profile is a J2ME profile specification. Layered on the Foundation Profile and CDC, the Personal Profile will be the next generation of Personal Java technology. The specification is currently in development under the Java Community Process (JCP).
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.
A MIDlet is an application written for MIDP. MIDlet applications are subclasses of the javax.micro edition.midlet.MIDlet class that is defined by MIDP
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.
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 Java
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.
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.
The Generic Connection Framework is the paradigm used for creating javax.micro edition.io.Connection objects that support different protocols. A URI defining the protocol and remote end-point for the network connection is passed to the javax.micro edition.io.Connector class via one of the open() methods and a javax.micro edition.io.Connection -type object is returned, ready to connect to the end-point.
There are currently two versions of the MIDP specification: version 1.0 and version 2.0 (reference to as MIDP-NG or MIDP Next Generation). The 1.0 specification was the first profile released under the Java ME umbrella in 2000. The 2.0 specification was released in 2002 and addressed many of the shortcomings of the original specification. The 2.0 specification is also backwards compatible with 1.0.
The manifest must contain at least the following fields:
- MIDlet-Name *
- MIDlet-Version *
- MIDlet-Vendor *
- MIDlet-# (where # is the MIDlet number, one for each MIDlet)
- Micro Edition-Profile
- Micro Edition-Configuration
What is a profile ?
A profile refers to the APIs for a specific domain. For example, the MIDP (Mobile Information Device Profile, defines the APIs that are made available for pervasive computing devices such as mobile phones, wireless PDAs and similar devices.
What are the minimum requirements for the CDC ?
For a device to support the CDC, it must have at minimum:
1.32-bit RISC/CISC processor
2.2M RAM
3.some form of network connectivity
What is a configuration ?
A configuration defines a virtual machine and the minimum APIs that must be present. In defining the virtual machine, the configuration specifies the minimum amount of memory that must be present as well as the minimum processor type and speed.
What is J2ME ?
J2ME is an term that refers to the collection of virtual machines, APIs and related elements that provide Java to handheld and embedded computing devices.
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