Java - Lets Start Journey

What is Java

Java programming language was originally developed by Sun Microsystems, which was initiated by James Gosling and released in 1995 as core component of Sun Microsystems.s Java platform (Java 1.0 [J2SE]).

As of December 08 the latest release of the Java Standard Edition is 6 (J2SE). With the advancement of Java and its wide spread popularity, multiple configurations were built to suite various types of platforms. Ex: J2EE for Enterprise Applications, J2ME for Mobile Applications.

Sun Microsystems has renamed the new J2 versions as Java SE, Java EE and Java ME respectively. Java is guaranteed to be Write Once, Run Anywhere

Java is:

• Object Oriented : In java everything is an Object. Java can be easily extended since it is based on the Object model.
• 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.
• Simple :Java is designed to be easy to learn. If you understand the basic concept of OOP java would be easy to master.
• Secure : With Java.s secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption.
• Architectural- neutral :Java compiler generates an architecture-neutral object file format which makes the compiled code to be executable on many processors, with the presence Java runtime system.
• Portable :being architectural neutral and having no implementation dependent aspects of the specification makes Java portable. Compiler and Java is written in ANSI C with a clean portability boundary which is a POSIX subset.
• Robust :Java makes an effort to eliminate error prone situations by emphasizing mainly on compile time error checking and runtime checking.
• Multi-threaded : With Java.s multi-threaded feature it is possible to write programs that can do many tasks simultaneously. This design feature allows developers to construct smoothly running interactive applications.
• Interpreted :Java byte code is translated on the fly to native machine instructions and is not stored anywhere. The development process is more rapid and analytical since the linking is an incremental and light weight process.
• High Performance: With the use of Just-In-Time compilers Java enables high performance.
• Distributed :Java is designed for the distributed environment of the internet.
• Dynamic : Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry extensive amount of run-time information that can be used to verify and resolve accesses to objects on run-time.

History of Java:

James Gosling initiated the Java language project in June 1991 for use in one of his many set-top box projects. The language, initially called Oak after an oak tree that stood outside Gosling's office, also went by the name Green and ended up later renamed as Java, from a list of random words.

Sun released the first public implementation as Java 1.0 in 1995. It promisedWrite Once, Run Anywhere (WORA), providing no-cost run-times on popular platforms.

On 13 November 2006, Sun released much of Java as free and open source software under the terms of the GNU General Public License (GPL).

On 8 May 2007 Sun finished the process, making all of Java's core code free and open-source, aside from a small portion of code to which Sun did not hold the copyright.

Tools you will need:

For performing the examples discussed in this tutorial, you will need a Pentium 200-MHz computer with a minimum of 64 MB of RAM (128 MB of RAM recommended).

You also will need the following softwares:

• Linux 7.1 or Windows 95/98/2000/XP operating system.
• Java JDK 5
• Microsoft Notepad or any other text editor

This tutorial will provide the necessary skills to create GUI, networking, and Web applications using Java.

Before we proceed further it is important that we set up the java environment correctly. This section guides you on how to download and set up Java on your machine. Please follow the following steps to set up the environment.

Java SE is freely available from the link Download Java. So you download a version based on your operating system.

Follow the instructions to download java and run the .exe to install Java on your machine. Once you installed Java on your machine, you would need to set environment variables to point to correct installation directories:

Setting up the path for windows 2000/XP:

Assuming you have installed Java in c:\Program Files\java\jdk directory:

• Right-click on 'My Computer' and select 'Properties'.
• Click on the 'Environment variables' button under the 'Advanced' tab.
• Now alter the 'Path' variable so that it also contains the path to the Java executable. Example, if the path is currently set to 'C:\WINDOWS\SYSTEM32', then change your path to read 'C:\WINDOWS\SYSTEM32;c:\Program Files\java\jdk\bin'.

Setting up the path for windows 95/98/ME:

Assuming you have installed Java in c:\Program Files\java\jdk directory:

• Edit the 'C:\autoexec.bat' file and add the following line at the end:
  'SET PATH=%PATH%;C:\Program Files\java\jdk\bin'

Setting up the path for Linux, UNIX, Solaris, FreeBSD:

Environment variable PATH should be set to point to where the java binaries have been installed. Refer to your shell documentation if you have trouble doing this.

Example, if you use bash as your shell, then you would add the following line to the end of your '.bashrc: export PATH=/path/to/java:$PATH'

Popular Java Editors:

To write your java programs you will need a text editor. There are even more sophisticated IDE available in the market. But for now, you can consider one of the following:

• Notepad : On Windows machine you can use any simple text editor like Notepad (Recommended for this tutorial), TextPad.
• Netbeans :is a Java IDE that is open source and free which can be downloaded from http://www.netbeans.org/index.html.
• Eclipse : is also a java IDE developed by the eclipse open source community and can be downloaded from http://www.eclipse.org/.