JAVA

Both the program and related documents on that program together is considered as a software. There is three basic stages when we are developing a program in any kind of language.

1. Design
2. Develop
3. Test

To develop computer programs we should select a programming language for that. There are many kind of languages that has been evaluated until now. If we categorize these languages as,

1. machine oriented (Low level Languages)
2. problem oriented (High level languages)

In first generations of programming languages they used binary values to program software. So the programmer should have very good knowledge about hardware implementation of the system and how does circuits operates. In second generation languages we used assembly language which used mnemonics (Simple English words) to represent simple instructions such as add, store instead on binary instructions which used in first generation. But still the programmer needed better understanding on machines. Third generation languages are more similar to English language. Programmers can program software without the knowledge of hardware. These languages can be categorized according to how they build the structure and elements of programs. Such as Procedural Programming, Functional Programming and Object Oriented programming, etc. All the second and third generation languages need to be translated in to machine language. There are three basic kind of translators used.

• Assembler – translate assembly language to machine languages
• Interpreter – translate source code line by line to machine language and execute
• Compiler – translate whole source code in to a code called object code and execute line by line using interpreter to machine language

Java is a third generation object oriented programming language which use a compiler to translate it into a machine code. It use java compiler to translate the source code which use .java extension into object codes (byte code) which use .class extension and then using java virtual machine it execute the code line by line. Since it use two translation steps java source code is machine independent. Java virtual machine (depends on the operating system) runs top of the operating system so the byte code can be run on any operating system.