INTRODUCTION TO JAVA PROGRAMMING

INTRODUCTION TO JAVA PROGRAMMING

¨ Introduced by [James Gosling & team-mates] at Sun Micro-Systems.

¨ Was called Oak but then introduced as Java.

¨ Purpose:-

    à Platform Independence. 

    àNetworking & Internet

    àCan be used with electronic consumer devices.

¨ Java SE (standard edition)

¨ Java EE (Enterprise Edition)

¨ Java ME (Micro edition)

How JAVA is plat-form Independent

¨ Due to Java Architecture it is plat-form independent

¨ Main features of Java Architecture:-

à Java programming language (source program created).

à Java class files

à Java Application program Interface (java API)

à Java Virtual Machine (JVM).

JAVA Architecture

¨ Java does not have its own editor so we can use [Notepad]   to write programs.

¨ Source program is compiled using “javac” compiler in JDK     & after compilation java class file is created.

¨  These class Files are in the form of “Byte-Codes”.

Java Platform

¨JVM+API = Java platform

¨Java platform is different for different machines.

¨i.e. for UNIX, Windows , Mac are different for one another.

¨The variation in hardware environment is taken care by JVM.

¨Which makes Java programming Platform Independent.

    [ Write Once Compile Once & Run On Any Platform]

Role of JVM [Java Virtual Machine]

¨Most important component of java programming.

üJVM executes Java class files & Java API files as required to get output.

üJava API files have native methods that interact with local operating system [Unix , Mac , Windows etc].

Before you run your programs, you must compile them.

¨ compiler: Translates a computer program written in one language into another language.

¤ Java Development Kit includes a Java compiler.

¤ byte code: The Java compiler converts your source code   into a format named byte code that can be executed on   many different kinds of computers.

Feature Of JAVA 

¨ Safe

¨ Robust

¨ Multi-threaded

¨ Architecture Neutral

¨ Internet Ready

¨ Simple

Types of Java Program

¨ Using Java language two types of programs can be written.

¨ Application Programs

¨ Applet

¨ Application Programs:-

•     Used to run program in PC under control of O.S in that machine are called application programs.

¨ Applets:-

•     Java applets are form of Byte-codes that run in web browser using JVM and executed without any control of O.S in that machine.
• 
  
•      Used to add interactive contents to web pages , giving animations etc.