Java

1. Java Powered By: Arvind Department of Computer science and engineering Radha govind group of institutions,meerut

2. 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 inventors of the language. • Java was designed for the development of software for consumer electronic machines. Powerd By: Arvind

3. Java Milestones • 1990 : Sun microsystems decided to develop special software that could be used to manipulate consumer electronic devices. A team ( Green Project team) of Sun Microsystems programmers headed by James Gosling was formed to undertake this task. • 1991 : The team announced a new language named “Oak”. • 1992 : The team demonstrated the application of their new language. Powerd By: Arvind

4. 1993 : The World Wide Web appeared on the Internet and transformed the text based Internet into a Graphical-Rich environment. The Green Project Team came up with the idea of developing web applets (tiny programs) using the new language that could run on all types of computers connected to internet. • The team developed a Web Browser called “HotJava” to locate and run applet programs on Internet. • 1995 : oak was renamed “Java” due to some legal issues. Java is just a name and is not an acronym. Powerd By: Arvind

5. 1996 : Sun releases Java Development Kit 1.0 (JDK 1.0). • 1997 : Sun releases Java Development Kit 1.1 (JDK 1.1). • 1998 : Sun releases Java 2 with version 1.2 of the Software Development Kit (SDK 1.2). • 1999 : Sun releases Java 2 Platform, Standard Edition (J2SE) and Enterprise Edition (J2EE) Powerd By: Arvind

6. 2000 : J2SE with SDK 1.3 was released. • 2001 : J2SE with SDK 1.4 was released. • 2004 : J2SE with JDK 5.0 (instead of JDK 1.5) was released. This is known as J2SE 5.0. Powerd By: Arvind

7. Java features • Compiled and Interpreted • Platform-Independent and portable • Object oriented • Robust and Secure • Distributed • Familiar , Simple and small • Multithreaded and Interactive Powerd By: Arvind

8. High performance • Dynamic and Extensible • Ease of Development • Scalability and Performance • Monitoring and Manageability • Desktop Client • Core XML Support • Supplementary character support • JDBCRowSet Powerd By: Arvind

9. How Java Differs from C and C++ Java and C: • Java is not like C but major difference between java and C is that Java is an Object Oriented language and has mechanism to define classes and Objects. • Java team did not include some of the C features in Java. • Java does not include the C unique statement keywords sizeof and typedef. • Java does not contain the data type struct and union. Powerd By: Arvind

10. Java does not define the type modifiers keywords auto, extern, register, signed, unsinged. • Java does not support en explicit pointer type. • Java does not have a preprocessor and therefore we cannot use #define, #include, and #ifdef statement. • Java requires that the functions with no arguments must be declared with empty parenthesis and not with the void keyword as done in C. • Java adds new operators such as a instanceof and >>> . • Java adds labelled break and continue statements. • Java adds many features required for object oriented programming. Powerd By: Arvind

11. Java and C++ • Java is a true object oriented language while C++ is basically C with Object Oriented extension. That is what exactly the increment operator ++ indicates. • Java does not support operator overloading. • Java does not have template classes as in C++. • Java does not support multiple inheritance of classes. This is accomplished using a new feature called “interface” . • Java does not support global variables. Every variable and method is declared within a class and forms part of that class. Powerd By: Arvind

12. Java does not use pointers. • Java has replaced the destructor function with a finalize() function. • There are no header files in Java. While C++ is a superset of C, Java is neither a superset nor a subset of C or C++. Powerd By: Arvind

13. Why did java become famous ? • Platform Independence c/c++ c/c++ windows Linux Powerd By: Arvind

14. Why did java become famous ? • Platform Independence Java Java JVM for Linux JVM for windows Linux windows Powerd By: Arvind

15. JVM • Acronym for Java Virtual Machine. • An abstract computing machine, or virtual machine, JVM is a platform-independent execution environment that converts Java byte code into machine language and executes it. • Most programming languages compile source code directly into machine code that is designed to run on a specific microprocessor architecture or operating system, such as Windows or UNIX. • A JVM -- a machine within a machine -- mimics a real Javaprocessor, enabling Java byte code to be executed as actions or operating system calls on any processor regardless of the operating system. Powerd By: Arvind

16. For example, establishing a socket connection from a workstation to a remote machine involves an operating system call. Since different operating systems handle sockets in different ways, the JVM translates the programming code so that the two machines that may be on different platforms are able to connect. Powerd By: Arvind

17. JVM Responsibilities The JVM has three main responsibilities: • Manage class files, including loading and verification. • Executing programs (interpreting class files). • Interacting with the host system while performing 1 and 2. Powerd By: Arvind