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INTRODUCTION TO JAVA:
• In 1990, Sun Microsystems Inc. (US) was conceived a project to develop software for customer electronics devices that could be controlled by a remote. This project was called Stealth Project but later its name was changed to Green Project. In 1991, Bill Joy, James Gosling, and several others met in Aspen, Colorado to discuss this project. James Gosling was to identify the proper programming language for the project. Gosling thought C and C++ could be used to develop the project. But the problem they faced with them is that they were system dependent languages and hence could not be used on various processors, which the electronic devices might use. So started developing a new language, which was completely system independent. This language was initially called Oak. Since this name was registered by some other company, later it was changed to Java.
• Why the name Java? James Gosling and his team members were consuming a lot of coffee while developing this language. They felt that they were able to develop a better language because of the good quality coffee they consumed. So the coffee had its own role in developing this language and good quality coffee was exported to the entire world from a place called ‘Java Island’. Hence they fixed the name of the place for the language as Java. And the symbol for Java language is coffee cup and saucer.
• On Jan 23rd 1996, JDK 1.0 version was released. Today more than 4 million developers use Java and more than 1.75 billion devices run Java. Thus Java was pervaded the world. Java is software that enables users to run program on any type of computer system. Java is suitable for internet because of its independency. It eliminates a lot of security problems for data on internet. It is purely object-oriented language. This means Java program use classes and objects. Because of its lot of features we create our project report of Hospital Management System in this language.
JAVA HISTORY:
• Java is a general-purpose, object-oriented programming language developed by Sun Microsystems of USA in 1991.Originally called Oak by James Gosling (one of the inventor of the language). Java was invented for the development of software for consumer electronic devices like TVs etc. The main aim had to make java simple, portable and reliable.
• Java Authors: James , Arthur Van , and others
Following data shows the year and beginning of Java
1990
Sun decided to developed software that could be used for electronic devices. And the project called as Green Project head by James Gosling.
1991
Announcement of a new language named ―Oak‖
1992
The team verified the application of their new language to manage a list of home appliances using a hand held device.
1993
The World Wide Web appeared on the Internet and transformed the text-based interface to a graphical rich environment.
1994
The team developed a new Web browsed called ―Hot Java‖ to locate and run Applets.
1995
Oak was renamed to Java, as it did not survive ―legal‖ registration. Many companies such as Netscape and Microsoft announced their support for Java.
1996
Java language is now famous for Internet programming as well as a general purpose OO language.
1997
Sun releases Java Development Kit(JDK 1.1)
1998
Sun releases Software Development Kit (SDK 1.2)
1999
Sun releases Java 2 platform Standard Edition (J2SE) and Enterprise Edition(J2EE).
2000
J2SE with SDK 1.3 was released.
2002
J2SE with SDK 1.4 was released.
2004
J2SE with JDK 5.0 was released.
FEATURES OF JAVA:
• Apart from being a system independent language, there are other reasons too for the immense popularity of this language. Let us have a look at some of its features.
1. Simple
2. Object- oriented
3. Distributed
4. Robust and secure
5. System Independence
6. Scalability
7. High performance
8. Compiled and Interpreted
9. Platform Independent and portable
10. Simple and small
11. Multithreaded and Interactive
Simple:
• Java is a simple programming language. Rather than saying that this is the feature of Java, we can say that is the design aim of Java. When Java is developed, they wanted it to be simple because it has to work on electronic devices, where less memory is available. Now, the question is how Java is made simple? First of all, the difficult concepts of C and C++ have been omitted in Java. Next, Java Soft people maintained the same syntax of C and C++ in Java, so that a programmer who knows C or C++ will find Java already familiar.
Object-Oriented:
• Java is an object-oriented programming language. This means Java programs use objects and classes. What is an object? An object is anything that really exists I the world and can be distinguished from others. Everything that we see physically will come into this definition, for example, every human being, a book, a tree, and so on.
• A group of objects exhibiting same behavior will come under the same group called a class. A class represents a group name given to several objects. For example, take the dogs: Pinky, Nancy, Tom and Subbu. All of these dogs have same behavior and hence belong to the same group, called dog. So dog is the class name which contains 4 objects.
Distributed:
• Information is distributed on various computers on a network. Using Java, we can write programs, which capture information and distribute it in to the clients. This is possible because Java can handle the protocols like TCP/IP and UDP.
Robust and secure:
• Java is a most strong language which provides many securities to make certain reliable code. It is design as garbage –collected language, which helps the programmers virtually from all memory management problems. Java also includes the concept of exception handling, which detain serious errors and reduces all kind of threat of crashing the system.
• Security is an important feature of Java and this is the strong reason that programmer use this language for programming on Internet.
• The absence of pointers in Java ensures that programs cannot get right of entry to memory location without proper approval.
System Independence:
• Java’s byte code is not machine dependent. It can be on any machine with any processor and any operating system.
Scalability:
• Java platform can be implemented on a wide range of computers with varying levels of resources-from embedded devices to mainframe computers. This is possible because Java is compact and platform independent.
High Performance:
• The problem with interpreter inside the JVM is that it is slow. Because of this, Java programs used to run slow. To overcome this problem, along with the interpreter Java Soft people have introduced JIT compiler, which enhances the speed of execution. So now in JVM, both interpreter and JIT compiler work together to run the program.
Compiled and Interpreted
• Basically a computer language is either compiled or interpreted. Java comes together both these approach thus making Java a two-stage system.
• Java compiler translates Java code to Bytecode instructions and Java Interpreter generate machine code that can be directly executed by machine that is running the Java program.
Platform Independent and portable
• Java supports the feature portability. Java programs can be easily moved from one computer system to another and anywhere. Changes and upgrades in operating systems, processors and system resources will not force any alteration in Java programs. This is reason why Java has become a trendy language for programming on Internet which interconnects different kind of systems worldwide. Java certifies portability in two ways.
• First way is, Java compiler generates the bytecode and that can be executed on any machine. Second way is, size of primitive data types are machine independent.
Simple and small
• Java is very small and simple language. Java does not use pointer and header files, goto statements, etc. It eliminates operator overloading and multiple inheritance.
Multithreaded and Interactive
• Multithreaded means managing multiple tasks simultaneously. Java maintains multithreaded programs. That means we need not wait for the application to complete one task before starting next task. This feature is helpful for graphic applications.
PARTS OF JAVA:
• Sun Microsystems Inc. has divided Java into 3 parts-Java SE, Java EE and Java ME.
Java SE:
It is the Java Standard Edition that contains basic core Java classes. This edition is used to develop standard applets and applications.
Java EE:
It is the Java Enterprise edition and it contains classes that are beyond Java SE. In fact, we need Java SE in order to use many of the classes in Java EE. Java EE mainly concentrates on providing business solutions on a network.
Java ME:
It is the Java Micro Edition. Java ME is for developers who develop code for portable devices, such as a PDA or a cellular phone. Code on these devices needs to be small in size and should take less memory.