INTRODUCTION & FEATURE OF JAVA

Chapter-1

 Java introduction                                                                                         by-kunalpatiltech.blogspot.com

• ·         Introduction-

1.       Java is called the language of internet. It indues life into webpages with animation,behaviour,& intelligence.java make sure that the right information reachesat the right place across the network.

2.       Java is platform independent.it means that if you are working on a window platform & you want our application to look as if you are working on linux platform,you can do it.

3.       It is the first program that is not tied to any perticular operating system or any perticular hardware.it is a totally platform independent.

•   History of java- 

1.       Sun microsystems set up a team to develope a software for a consumer electronics. James ghosling headed the team. 

2.       First C++ was choosen for the development.but for some technical reason C++ was dropped & new language called Oak was developed. & Oak is used. 

3.       In this new language the concept of pointer is eliminated.& similarly multiple inheritance ,memory mgmt,& automatic type conversion was also eliminated. 

4.       In 1994,internet was very popular.they  found  java a very appropriate lang.for the internet.they named the lang.as JAVA. They  also developed the browser called HOTJAVA.this was first browser to support JAVA.JAVA introduce in 1995. 

5.       Sun microsystem has released java development kit  1.2 (JDK 1.2) with a number of facility.  

• ·         WHAT IS JAVA ?- 

Sun microsystem describe java as simple,robust,object-oriented,architecture neutral,portable,multithreaded & dynamic languge.

• Features of java-

1.       Simple-

JAVA is simple because it is easy to learn.JAVA uses many constraints of C & C++. So it is easy for c & C++ programmer to migrate to JAVA.JAVA is eliminated the use of multiple inheritance as in C++.The most imp. Aspect of JAVA  being SIMPLE,& it does not use POINTERS.POINTERS are most prone aspects.Memory management issues need not be taken into account as JAVA implements automatic garbage collection.

2.       Object-Oriented- 

      JAVA is truly OBJECT-ORIENTED Lang.(OOL)In OOL, class is a collection of data & methods.The state & behaviour of an object is described by the data & methods taken together.Eg.- if animal is a classs then we have color & height as data & method as speed. The object of these class can be lion ,tiger etc.

3.       Interpreted:-

                                                              JAVA prog. Is both compiled & interprited.With JAVA compiler you  can  translate the java prog. Into a intermediate lang. called JAVA BYTECODES. These bytecode are the platform independent codes.These bytecodes are interprited by by java interpreter.With an interpriter,each java bytecodes is parsed & run on the computer.Remember  that  Compilation Occurs only one time,but interpritation occurs each time the prog. Is executed.These bytecodes can be run on any machine which has implementation for the java interpreter & the runtime system.Remember that,the interpreter & the runtime system collectively called as JAVA VIRTUAL MACHINE [JVM].Java prog. Can be compiled on any machine that has java compiler.The bytecodes can then be run on any machine that has the JVM.The same prog. Can be run on windows,linux,solaries etc.  

4.       Robust-

JAVA has been designed to develop robust software.Memory related prob. Are excluded due to exclusion of pointers.Java interpreter performs several runtime checkes toverify whether the arrays are within bounds.Exception handeling facilitates the programmer to identify the errors & correct it.

5.       Secure-

Since JAVA does not support pointers,memory manipulation is not possible in JAVA  as in case of C,which is a major defence against malicious classes do not replace the existing classes.

6.       Architecture Neutral-

JAVA compiler produses bytecodes that are platform independent.so the prog. Can be executed on any platform if the o.s. has a JVM.only the appearance of the component will differ from platform.EVEN the appearance can be made uniform by using Swing components.

7.       Portable-

A portable lang. is one which can run on all operating System & on all the processor irrespective their architectures.The lang like C,C++ are treated as non portable lang. & where as JAVA is Portable lang.

8.       High performance-

Java is  much fast as compared to c,c++.

9.       Multithreaded-

Java is multithreaded lang.It provide facility for executing the multiple threads at a time that can perform different task at the same time.All the major application on the net is graphical.Programing with thread is very simple as compared to c.Java provides a called java lang package that supports the methods to start a thread,stop a thread,&check the status of the thread.