Byjavawithease

Java was originally designed by Sun Microsystems Inc. Work Started on 1991 First Version was released on 1995 named Java 1.0 James Gosling is known as father of Java, he was the Vice President of Sun Microsystem till 2010 Recently Sun Microsystems is taken over by Oracle Incorporation

Java

J2SE J2EE Java CardJ2ME

certifications for Java technologies:

* Java Platform, Standard Edition (Java SE) o Sun Certified Java Associate o Sun Certified Java Programmer o Sun Certified Java Developer

* Java Platform, Enterprise Edition (Java EE) o Sun Certified Web Component Developer o Sun Certified Business Component Developer o Sun Certified Developer for Java Web Services o Sun Certified Enterprise Architect

* Java Platform, Micro Edition (Java ME) o Sun Certified Mobile Application Developer

Java is a Programming Language Java is a Development Environment Java is an Application Environment Java is a Deployment Environment

Simple to program Platform Independent Portable Robust and Secure Speedup the Development Based on OOPs Multithreaded

There are four tools that make Java as Java

JVM (Java Virtual Machine) JRE (Java Runtime Environment) Garbage Collection JVM tools interface

JVM is an imaginary machine which works like an emulator at the runtime. All the JVM code stores in .class file which is generated after compilation. The codes inside .class file is known as Bytecodes and these Bytecodes is the language of JVM

a.java compiler a.class

Windows

UNIX/LINUX

Mac

JVM

JRE Contains:

Class Loader Bytecodes Verifier Interpreter/JIT Compiler Runtime Hardware

a.java

a.class

compiler

Load from Hard disk,

network module

Class loader

Bytecodes verifier

Hardware

Interpreter

Runtime

In c, C++ we were responsible for the de-allocation of memory. This was a difficult exercise at times , because we do not always know in advance when memory should be released.

The Java Programming language removes your from the responsibility of de-allocating memory. It provide a system level thread that tracks each memory allocation.

Advantage: Save data from Memory Leaks

public class HelloWorld{

private String message=“Welcome in Java Programming”;public String sayHello(){

System.out.println(message);return message;

}public static void main(String[] args){

HelloWorld hello=new HelloWorld();hello.sayHello();

}}

Output:Welcome in Java Programming