History Of Java

Java is general purpose, pure object oriented programming language developed by sun microsystem of USA in early 1990’s. Originally Java was called Oak, James Gosling gave this name by being inspired from an oak tree in front of his office.  He is one of the inventors of the Java. Java is designed for the development of software for consumer electronic devices like TVs, VCRs and other electronic machines. Java applets were launched in the begging later when those got popular then Sun launched JDK 1.0 (Java Development Kit) on 23^rd January 1996. Current version of JDK is 1.7, you can download it from sun’s official website. You can also download a Java IDE (Intellingent Development Environment) like Netbeans or Eclipse

Types of Java Programs

• Applications (Desktop Softwares/Applications)
• Applets (Web Pages)

Features Of Java

• Compiled and Interpreted
• Usually a language is either compiled or interpreted but  Java programs are both compiles as well as interpreted. Java compiler first compiles the program and converts its source code into byetcode.  Only JVM (Java Virtual Machine) can understand this code (More on JVM Later). When Java application is executed JVM’s interpreter converts byetcode into machine code, that can be directly executed by the machine.  In JVM(Java Virtual Machine) there is just in time compiler which increases the conversion time of interpreter .

• Platform Independent and Portable
• Java programs are platform independent i.e. we can compile our program on one type of operating system and can run on another type of operating system without any difficulties. This is because Java compiler converts the source code into byetcode which is save in a files with .class extension. This file can only be read by JVM. This means that we just need JVM installed on the system for execution of a Java program. JVM is a part of JDK, which is available for all the common operating systems present till now.

• Object Oriented
• Java is pure object oriented language because whole program reside inside a class. Set of class is called package in Java. In program we include these classes by using “import” keyword.

• Secure
• In Java there are no pointer, that’s why program cannot gain access to memory location without proper authorization. Java validates the program in two stages i.e. at the time of compilation (conversion to byetcode) and at the time of interpretation (conversion to machine code or execution)