UMETSHistory of Java and Tour of JDK
Java is an object-oriented programming language developed by Sun Microsystems, and modeled on C++, the Java language was designed to be small, simple, and portable across platforms and operating systems, both at the source and at the binary level, which means that Java programs (applets and applications) can run on any machine that has the Java virtual machine installed One might be surprised to learn that Java did not come into being because of Internet or World Wide Web (WWW), although it was WWW which propelled into java what it is as a language today and a de-facto standard for Server Side Softwares. Because of the similarities between C++ and Java, it is tempting to think of Java as the “Internet version of C++”, but it would be a big mistake since Java has practical and philosophical difference with C++. The history of java goes back to 1991, when a group of Sun Engineers led by Mr. Patrick Naughton and James Gosling wanted to design a small computer language that was to be used for consumer and electronic devices like Remote Controls, TV Switchboxes etc. Now since these devices were manufactured by different manufacturers who may choose different CPUs (Central Processing Units), the program should not be tied down to any single architecture. The project was code named “Green”. The languages was then called as Oak and since Oak was already an existing computer languages, it was code named as JAVA. But unfortunately, Sun did not get the project for which they were bidding and it was in 1994 with the advent of the WWW and browsers, java was propelled back in to the main stream. The JAVA as a language was reveled to the world in the Sun world 1995 conference and from there onwards different versions have come out with all the latest technologies being incorporated. The different versions are being dealt with separately in the coming modules. Java was basically invented as a platform independent software to be run on various electronic devices like remote controls, micro-wave ovens etc. The emphasis was on platform independence. Platform independence-that is, the ability of a program to move easily from one computer system to another-is one of the most significant advantages that Java has over other programming languages, particularly if your software needs to run on many different platforms. If you're writing software for the World Wide Web, being able to run the same program on many different systems is crucial to that program's success. It was with the increasing popularity of the Internet, java became as a language for the internet which lays emphasis on the client-server programming. Java achieves this platform independence by breaking up the process of compilation and interpretation in to two individual steps. We have two separate executable files for this purpose called the Compiler and the Interpreter. In the earlier programming languages, any code written was compiled and immediately interpreted to the underlying operating system machine standard and hence if the same program was taken to another machine having a different operating system, it would not work.
In Java, after compilation a class file is generated which is also called as byte code file and this class file is then interpreted as per the underlying machine standard. If we take this class file from one machine to another, it would still run, because interpretation is done as per that machine’s operating system. The Java compiler takes your Java program and, instead of generating machine codes from your source files, it generates bytecodes. Bytecodes are instructions that look a lot like machine code, but are not specific to any one processor. To execute a Java program, you run a program called a Bytecode interpreter, which in turn reads the bytecodes and executes your Java program. The Java Bytecode interpreter is often also called the Java virtual machine or the Java runtime Java bytecodes are a special set...
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