Basic of Java - Part 1

Basic of Java

Communication and Human Being

When we are communicating with somebody what exactly we need? The most important thing that we need is communication medium. There must be some common means of interaction. This leaded to birth of language. Initially the human communicated with each other with the help of sign language. When man came to know about the ability of different sounds they can produce they started talking in voice medium. Gradually he created the different languages that we hear today and this is how the journey of language started.

This communication was restricted to human communication but till 20^th century human was very powerful in the terms of technology and he developed many electric and electronic devices and one of them was COMPUTER. This device was so powerful that it was able to manage 1000 times’ faster & efficient work than man. Computer was very much accurate than a man’s calculation.

Evolution of Computer Languages

But when this machine was invented it was very difficult to communicate with it. The language used at that time was very complex to use as well as to learn. This problem put man into finding new solution for it. The solution was a language which should be easy to understand and simple to learn. But at the same time most important aspect was it should be computer friendly i.e. machine also should interpret it quickly. In the beginning many languages were found to solve the issue but they were not much effective.

In 1972, Dennis Ritchie came with a language called C. This language changed the face of whole programming world. This language got the popularity in very less time and the reason was its user-friendly structure and fast execution. But soon the drawbacks of this language came forward and we needed a more powerful language. C was very handy in small programs but as code grows beyond some thousand lines compiler crashes. Also C was not very helpful in dealing with real world problems. This turned out in evolution of C++, a new object oriented language. This language also took the attentions of all the programmers. But soon there was a drastic change in the programming world.

By 1990’s inventors found that people have started using OSs other than Windows and they wanted a language which would be platform independent or platform neutral. Till this time nobody had thought of this kind of thing. And Sun Microsystems came up with this concept first in 1991 with Star OS. But at that time this concept was super flop as the people were much more addicted to what they had with them. In 1995, this problem was encountered and people found the thing very useful. And then Patrick Naughton, James Gosling, Ed Frank, Mike Sheridan and Chris Warth came up with the same concept with different name as “JAVA”. Java was initially known as “Oak” and later in 1995 it was renamed as Java.

Introduction to Programming

What is programming? In simple words Programming is nothing but finding solutions to given problems. Computer Programming is the art of making a computer do what you want it to do. Simply Program is a sequence or a set of instructions to the computer that will achieve your objective.

Programming is planning how to solve a problem. No matter what method is used -- pencil and paper, slide rule, adding machine, or computer -problem solving requires programming. Of course, how one programs, depends on the device one uses in problem solving.

Program can be written in any language that is preferred by the programmer. We have many programming languages to write programs like C, C++, JAVA, etc.

Introduction to Computer Science using 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. It’s a complete course in java programming for beginners to advanced java.

Platform independent

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.

Java Virtual Machine

What is the Java Virtual Machine? What is its role?
Java was designed with a concept of ‘write once and run everywhere’. Java Virtual Machine plays the central role in this concept. The JVM is the environment in which Java programs execute. It is a software that is implemented on top of real hardware and operating system. When the source code (.java files) is compiled, it is translated into byte codes and then placed into (.class) files. The JVM executes these bytecodes. So Java byte codes can be thought of as the machine language of the JVM. A JVM can either interpret the bytecode one instruction at a time or the bytecode can be compiled further for the real microprocessor using what is called a just-in-time compiler. The JVM must be implemented on a particular platform before compiled programs can run on that platform.

Object Oriented Programming

Since Java is an object oriented programming language it has following features:

• Reusability of Code
• Emphasis on data rather than procedure
• Data is hidden and cannot be accessed by external functions
• Objects can communicate with each other through functions
• New data and functions can be easily added

Java has powerful features. The following are some of them:-

Simple
Reusable
Portable (Platform Independent)
Distributed
Robust
Secure
High Performance
Dynamic
Threaded
Interpreted

Object Oriented Programming is a method of implementation in which programs are organized as cooperative collection of objects, each of which represents an instance of a class, and whose classes are all members of a hierarchy of classes united via inheritance relationships.


OOP Concepts
Four principles of Object Oriented Programming are
Abstraction
Encapsulation
Inheritance
Polymorphism


Abstraction
Abstraction denotes the essential characteristics of an object that distinguish it from all other kinds of objects and thus provide crisply defined conceptual boundaries, relative to the perspective of the viewer.
EncapsulationEncapsulation is the process of compartmentalizing the elements of an abstraction that constitute its structure and behavior ; encapsulation serves to separate the contractual interface of an abstraction and its implementation.
Encapsulation
* Hides the implementation details of a class.
* Forces the user to use an interface to access data
* Makes the code more maintainable.
Inheritance
Inheritance is the process by which one object acquires the properties of another object.
Polymorphism
Polymorphism is the existence of the classes or methods in different forms or single name denoting different
implementations.

Java is Distributed

With extensive set of routines to handle TCP/IP protocols like HTTP and FTP java can open and access the objects across net via URLs.

Java is Multithreaded

One of the powerful aspects of the Java language is that it allows multiple threads of execution to run concurrently within the same program A single Java program can have many different threads executing independently and continuously. Multiple Java applets can run on the browser at the same time sharing the CPU time.

Java is Secure

Java was designed to allow secure execution of code across network. To make Java secure many of the features of C and C++ were eliminated. Java does not use Pointers. Java programs cannot access arbitrary addresses in memory.

Garbage collection

Automatic garbage collection is another great feature of Java with which it prevents inadvertent corruption of memory. Similar to C++, Java has a new operator to allocate memory on the heap for a new object. But it does not use delete operator to free the memory as it is done in C++ to free the memory if the object is no longer needed. It is done automatically with garbage collector.

Java Applications

Java has evolved from a simple language providing interactive dynamic content for web pages to a predominant enterprise-enabled programming language suitable for developing significant and critical applications. Today, It is used for many types of applications including Web based applications, Financial applications, Gaming applications, embedded systems, Distributed enterprise applications, mobile applications, Image processors, desktop applications and many more. This site outlines the building blocks of java by stating few java examples along with some java tutorials.