JAVA BASICS

Understanding Java

Java is a technology introduced by Sun Microsystems in the mid-year 1990. According to the definition of Sun, Java is the name for a set of technologies to create and run the software on a standalone computer or in a network environment. We prefer to call Java as a technology rather than just a programming language, because Java is more complete than a conventional programming language. Java technology has three important components, namely:

· Programming-language specification

· Application-programming interface

· Virtual-machine specification

 B. Java API

Java API consists of three main parts:

· Java Standard Edition (SE), a standard API for designing desktop applications and applets with the basic language that supports graphics, M / C, security, database connectivity and network.

· Java Enterprose Edition (EE), an initiative of the API to design an application server with support for databases.

· Java Macro Edition (ME), an API to design applications that run on small devices like mobile phones, handheld computers and pagers.

  

C. Java Virtual Machine

Java Virtual Machine (JVM) is a specification for an abstract computer. JVM consists of a class of the caller and an interpreter that executes Java architecture neutral code. Class caller to call the file. The second class of Java programs and Java APIs to be executed by a Java interpreter. Java interpreter may be a software interpreter that translates one byte code at a time, or maybe a just-Intime (JIT) compiler that reduces the architecture neutral bytecode into machine language for the host computer.

  

D. Java Operating System

The operating system is usually written in a combination of C and assembly code bahssa, mainly due to the excess performance of the language and facilitate communication with the hardware.

One difficulty in designing a language is the base system in terms of memory protection, which protects the system from user programs opeasi deliberately protect users of other programs. Expect traditional operating system on the display hardware to provide memory protection. Language base system relies on the security view of language. As a result, the system wanted the language base in a small hardware device, which may lack the display hardware that provides memory protection.

  

E. Basic Programming

Java2 is the second generation of the Java platform (first generation is the Java Development Kit). Java stand on a machine called JVM interpreter. JVM bytecode is to be read in the file. Class of a program as a direct representation of a program that contains machine language. Therefore, the Java language called a programming language that is portable as it can run on different operating systems, provided that the operating system there are JVM.

Java Platform consists of a collection of libraries, JVM, class loaders-class packaged in a regular Java environment, and a compiler, debuger, and other devices are packaged in the Java Development Kit (JDK). Java2 is now a growing generation of platformJava. In order for a Java program can run, then files with the extension.''''Should be compiled into java bytecode file. To run the bytecode is required JRE (Java Runtime Environment) that allows users to run Java programs, just run, not to create new code again. Contains the JVM and JRE libraryJava used.

PlatformJava have three different editions, ie J2EE (Java2 Enterprose Edition), J2ME (Java2 Micro Edition) and J2SE (Java2 Second Edition). J2EE is a group of several APIs (Application Programming Interface) of Java and other Java technologies. J2EE is often regarded as a middleware or technology that runs on the server, but actually J2EE is not limited to it. In fact J2EE also includes technology that can be used in all layers of an information system. Implementation of J2EE provides basic classes and APIs from Java that supports the development of a standard routine for client and server applications, including applications that run in a web browser. J2SE is the foundation of the Java environment, while the J2ME is a library edition designed for use on certain devices such as pagers and mobile phones.

Java is a language that pemrogrman are case sensitive, which means writing using capital letters or small letters on the source code to other means. For example, writing "System" will be interpreted differently by the "system" by the interpreter. Java does not like C + +, Java does not support procedural programming, but it supports object-oriented programming so that there is a class in source code syntax. 

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