INTRODUCTION TO JAVA

INTRODUCTION  TO    JAVA

Any technology or language before learning we need to think below things

1.where this language used mostly?

2.what is main difference between this and other?

3.what is it actually?

3.how to use it?

where java language is used?

Java mostely used to develop web applications like(eg banking websites,reservation)Besides the above technology, Java is also used for various entertainment devices especially mobile phone. Mobile Information Devices Profile (MIDP) uses Java run time environment in cell phones, mobile tracking systems and other traditional PDA devices. Java technology enabled application is key to the games and services available in the mobile world. This also plays an important role in the field of telemedicine such as PulseMeter. As far as mobile technology is concerned, it offers offline facility, so that users can get service even if they face loss of connection. Today, all leading mobile service provider like Nokia, Siemens, Vodafone are using Java technology. Sun Java Wireless Toolkit offers complete support for developing different MIDP application.

what is java?

Java is a simple and yet powerful object oriented programming language and it is in many respects similar to C++. Java originated at Sun Microsystems, Inc. in 1991. It was conceived by James Gosling, Patrick Naughton, Chris Warth, Ed Frank, and Mike Sheridan at Sun Microsystems, Inc. It was developed to provide a platform-independent programming language. This site gives you an Introduction to Java Programming accompanied with many java examples. Its a complete course in java programming for beginners to advanced java.
why we need to choose?

Unlike many other programming languages including C and C++ when Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by virtual Machine (JVM) on whichever platform it is being run.
The concept of Write-once-run-anywhere (known as the Platform independent) is one of the important key feature of java language that makes java as the most powerful language.

 How to use it?

We need to install any jdklatest version is jdk 1.7after that we need to set path Select Computer from the Start menuChoose System Properties from the context menuClick Advanced system settings > Advanced tabClick on Environment Variables, under System Variables, find PATH, and click on it.In the Edit windows(C:\Program Files\Java\jdk1.6.0_37\bin), modify PATH by adding the location of the class to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the location of the class as the value.Reopen Command prompt window, and run your java code.We can write  java code using any editor like notepad,editplusor ides like elipse,netbeans      

Java Features

Platform Independent

The concept of Write-once-run-anywhere (known as the Platform independent) is one of the important key feature of java language that makes java as the most powerful language. Not even a single language is idle to this feature but java is more closer to this feature. The programs written on one platform can run on any platform provided the platform must have the JVM.SimpleThere are various features that makes the java as a simple language. Programs are easy to write and debug because java does not use the pointers explicitly. It is much harder to write the java programs that can crash the system but we can not say about the other programming languages. Java provides the bug free system due to the strong memory management. It also has the automatic memory allocation and deallocation system.

Object Oriented

To be an Object Oriented language, any language must follow at least the four characteristics.

Inheritance  

 It is the process of creating the new classes and using the behavior of the existing classes by extending them just to        reuse  the existing code and adding the additional features as needed

Encapsulation: 

  It is the mechanism of combining the information and providing the abstraction.Polymorphism:  As the name suggest one name multiple form, Polymorphism is the way of providing the different functionality by the   functions  having the same name based on the signatures of the methods.

Dynamic binding  : 

  Sometimes we don't have the knowledge of objects about their specific types while writing our code. It is the way     of providing the maximum functionality to a program about the specific type at runtime.As the languages like Objective C, C++ fulfills the above four characteristics yet they  are not fully object oriented languages because they are structured as well as object oriented languages. But in case of java,  it is a fully Object Oriented language because object is at the outer most level of data structure in java. No stand alone methods, constants, and variables are there in java. Everything in java is object even the primitive data types can also be converted into object by using the wrapper class.

Robust

Java has the strong memory allocation and automatic garbage collection mechanism. It provides the powerful exception handling and type checking mechanism as compare to other programming languages. Compiler checks the program whether there any error and interpreter checks any run time error and makes the system secure from crash. All of the above features makes the java language robust.

Distributed

The widely used protocols like HTTP and FTP are developed in java. Internet programmers can call functions on these protocols and can get access the files from any remote machine on the internet rather than writing codes on their local system.

Portable

The feature Write-once-run-anywhere  makes the java language portable provided that the system must have interpreter for the JVM. Java also have the standard data size irrespective of operating system or the processor. These features makes the java as a portable language.

Dynamic

While executing the java program the user can get the required files dynamically from a local drive or from a computer thousands of miles away from the user just by connecting with the Internet.

Secure

Java does not use memory pointers explicitly. All the programs in java are run under an area known as the sand box. Security manager determines the accessibility options of a class like reading and writing a file to the local disk. Java uses the public key encryption system to allow the java applications to transmit over the internet in the secure encrypted form. The bytecode Verifier checks the classes after loading.

Performance

Java uses native code usage, and lightweight process called  threads. In the beginning interpretation of bytecode resulted the performance slow but the advance version of JVM uses the adaptive and just in time compilation technique that improves the performance.

Multithreaded

As we all know several features of Java like Secure, Robust, Portable, dynamic etc; you will be more delighted to know another feature of Java which is Multithreaded.Java is also a Multithreaded programming language. Multithreading means a single program having different threads executing independently at the same time. Multiple threads execute instructions according to the program code in a process or a program. Multithreading works the similar way as multiple processes run on one computer. Multithreading programming is a very interesting concept in Java. In multithreaded programs not even a single thread disturbs the execution of other thread. Threads are obtained from the pool of available ready to run threads and they run on the system CPUs. This is how Multithreading works in Java which you will soon come to know in details in later chapters.

Interprete

We all know that Java is an interpreted language as well. With an interpreted language such as Java, programs run directly from the source code.The interpreter program reads the source code and translates it on the fly into computations. Thus, Java as an interpreted language depends on an interpreter program.The versatility of being platform independent makes Java to outshine from other languages. The source code to be written and distributed is platform independent. Another advantage of Java as an interpreted language is its error debugging quality. Due to this any error occurring in the program gets traced. This is how it is different to work with Java.

Architecture Neutral

The term architectural neutral seems to be weird, but yes Java is an architectural neutral language as well. The growing popularity of networks makes developers think distributed. In the world of network it is essential that the applications must be able to migrate easily to different computer systems. Not only to computer systems but to a wide variety of hardware architecture and Operating system architectures as well.  The Java compiler does this by generating byte code instructions, to be easily interpreted on any machine and to be easily translated into native machine code on the fly. The compiler generates an architecture-neutral object file format to enable a Java application to execute anywhere on the network and then the compiled code is executed on many processors, given the presence of the Java runtime system. Hence Java was designed to support applications on network. This feature of Java has thrived the programming language