Introduction To Java part 1

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' Java platform (Java 1.0 [J2SE]).

As of December 2008, the latest release of the Java Standard Edition is 6 (J2SE). With the advancement of Java and its widespread 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 of Java runtime system.
• Portable:Being architectural-neutral and having no implementation dependent aspects of the specification makes Java portable. Compiler in 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.
• Multithreaded: With Java's multithreaded 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.

1.1 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 being renamed as Java, from a list of random words.

Sun released the first public implementation as Java 1.0 in 1995. It promised Write 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.

1.2 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.

1.3 Try It Option:

We have provided you an option to compile and execute available code online. Just click on Try itbutton avaiable at top-right corner of the code window to compile and execute available code. There are certain examples which can not be executed online, so we have skipped those examples.

TRY THIS CODE:

public class MyFirstJavaProgram {

    public static void main(String []args) {

       System.out.println("Hello World");

    }

} 

OUTPUT:

Hello World

2. Java Environment Setup

Step1:

First we need to install JDK(Java Development Kit)

Choose Java Platform (JDK) 7u45









Step 2:

Accept Licence Agreement and see download link at bottom select file as per your os. If you have 32 bit windows.

Download the file & installation is very easy just follow the instruction

Once you installed Java on your machine, you would need to set environment variables to point to correct installation directories: First we need to copy the path of jdk, bin folder path Go to C drive > Program Files > Java > jdk Folder > bin folder and copy the path




Step3:

There are two ways doing it.. 

1. Temporary set path Open command prompt Click on start and search box type cmd and enter

2.Once it open give your copied path like this “path=C:\Program Files\Java\jdk1.7.0_45\bin”



3.To check whether the path is set or not type javac and enter and you will see java options that means your path is set and ready to run java programs






4. Permanent way to set path Hope you have copied the jdk folder path which is explained above Click on Start > Right Click on Computer and click Properties

5.Then go to Advance system setting or you can simply type in start search box for advance system setting





6.System properties dialog box will open click on Environment Variables



7.Click on new in System Variable. Note:Don’t add path in user variable it will not work Add Variable name as path. Note: anything else than path will not work like java or sdk And Variable value as path you copied with Semicolon at end. Note: don’t forget to add semicolon(;) at end



8.To check whether the path is set or not Open command prompt and type javac and enter and you will see java options that means your path is set and you are ready to run java programs




Running Java Program
Open your favorite text editor
And type this program or simply copy it

class testing
 {
 public static void main(String args[])
 {
  System.out.println("Hey! This is my First Java Program..");
 }
}


Then save it as .java extension. I saved it to my F drive in sush folder
Note: save your program with your class name Otherwise it won’t run. 




2.1 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 IDEs 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 fromhttp://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/.