JAVA

Java is an object-oriented programming language developed by Sun Microsystems that plays to the strengths of the Internet.
Object-oriented programming (OOP) is an unusual but powerful way to develop software. In OOP, a computer program is considered to be a group of objects that interact with each other.

Consider an embezzlement program implemented with Java: A Worker object skims some Money objects from the CompanyFunds object and puts them in its own BankAccount object. If another Worker object uses the DoubleCheckFunds object, a Police object will be called.

The feature that is best known about Java is that it can be used to create programs that execute from World Wide Web pages. These programs are called applets.
Java programs made a big splash on the Web because they offered interactivity in a medium that was largely one way. The Web distributes almost all information in a passive manner. Someone using a browser asks for a page, looks it over, asks for another, looks it over, and so on. Lather, rinse, repeat.
A Java applet running on a Web page provides a much richer experience--both in terms of information and user interaction. Information can change in response to user input or be updated dynamically as a Web page is viewed. Figure 1.3 shows an example of a Java applet that dynamically updates itself. The applet, offered by JavaWorld magazine (at the URL http://www.javaworld.com) in conjunction with Quote.Com, updates a stock portfolio dynamically with quotes updated in real time.

Why Java Is Internationally Beloved

Platform Independent:

The concept of Write-once-run-anywhere (known as the Platform independent) is one of the important key feature of java language that makes java as the most powerful language. Not even a single language is idle to this feature but java is more closer to this feature. The programs written on one platform can run on any platform provided the platform must have the JVM.

Simple:

There are various features that makes the java as a simple language. Programs are easy to write and debug because java does not use the pointers explicitly. It is much harder to write the java programs that can crash the system but we can not say about the other programming languages. Java provides the bug free system due to the strong memory management. It also has the automatic memory allocation and deallocation system.

Object Oriented:

To be an Object Oriented language, any language must follow at least the four characteristics.

Inheritance: It is the process of creating the new classes and using the behavior of the existing classes by extending them just to reuse the existing code and adding the additional features as needed.
Encapsulation: It is the mechanism of combining the information and providing the abstraction.
Polymorphism: As the name suggest one name multiple form, Polymorphism is the way of providing the different functionality by the
functions having the same name based on the signatures of the methods.
Dynamic binding : Sometimes we don't have the knowledge of objects about their specific types while writing our code. It is the way of providing the maximum functionality to a program about the specific type at runtime.

As the languages like Objective C, C++ fulfills the above four characteristics yet they are not fully object oriented languages because they are structured as well as object oriented languages. But in case of java, it is a fully Object Oriented language because object is at the outer most level of data structure in java. No stand alone methods, constants, and variables are there in java. Everything in java is object even the primitive data types can also be converted into object by using the wrapper class.

Robust:

Java has the strong memory allocation and automatic garbage collection mechanism. It provides the powerful exception handling and type checking mechanism as compare to other programming languages. Compiler checks the program whether there any error and interpreter checks any run time error and makes the system secure from crash. All of the above features makes the java language robust.

Distributed:

The widely used protocols like HTTP and FTP are developed in java. Internet programmers can call functions on these protocols and can get access the files from any remote machine on the internet rather than writing codes on their local system.

Portable:

The feature Write-once-run-anywhere makes the java language portable provided that the system must have interpreter for the JVM. Java also have the standard data size irrespective of operating system or the processor. These features makes the java as a portable language.

Dynamic:

While executing the java program the user can get the required files dynamically from a local drive or from a computer thousands of miles away from the user just by connecting with the Internet.

Secure:

Java does not use memory pointers explicitly. All the programs in java are run under an area known as the sand box. Security manager determines the accessibility options of a class like reading and writing a file to the local disk. Java uses the public key encryption system to allow the java applications to transmit over the internet in the secure encrypted form. The bytecode Verifier checks the classes after loading.

Performance:

Java uses native code usage, and lightweight process called threads. In the beginning interpretation of bytecode resulted the performance slow but the advance version of JVM uses the adaptive and just in time compilation technique that improves the performance.

Multithreaded

As we all know several features of Java like Secure, Robust, Portable, dynamic etc; you will be more delighted to know another feature of Java which is Multithreaded.

Java is also a Multithreaded programming language. Multithreading means a single program having different threads executing independently at the same time. Multiple threads execute instructions according to the program code in a process or a program. Multithreading works the similar way as multiple processes run on one computer.

Multithreading programming is a very interesting concept in Java. In multithreaded programs not even a single thread disturbs the execution of other thread. Threads are obtained from the pool of available ready to run threads and they run on the system CPUs. This is how Multithreading works in Java which you will soon come to know in details in later chapters.

Interpreted:

We all know that Java is an interpreted language as well. With an interpreted language such as Java, programs run directly from the source code.
The interpreter program reads the source code and translates it on the fly into computations. Thus, Java as an interpreted language depends on an interpreter program.

The versatility of being platform independent makes Java to outshine from other languages. The source code to be written and distributed is platform independent.

Another advantage of Java as an interpreted language is its error debugging quality. Due to this any error occurring in the program gets traced. This is how it is different to work with Java.

Architecture Neutral:

The term architectural neutral seems to be weird, but yes Java is an architectural neutral language as well. The growing popularity of networks makes developers think distributed. In the world of network it is essential that the applications must be able to migrate easily to different computer systems. Not only to computer systems but to a wide variety of hardware architecture and Operating system architectures as well. The Java compiler does this by generating byte code instructions, to be easily interpreted on any machine and to be easily translated into native machine code on the fly. The compiler generates an architecture-neutral object file format to enable a Java application to execute anywhere on the network and then the compiled code is executed on many processors, given the presence of the Java runtime system. Hence Java was designed to support applications on network. This feature of Java has thrived the programming language.

HTML

HTML, which stands for HyperText Markup Language, is a markup language used to create web pages. The web developer uses "HTML tags" to format different parts of the document. For example, you use HTML tags to specify headings, paragraphs, lists, tables, images and much more.

HTML is a subset of Standard Generalized Markup Language (SGML) and is specified by the World Wide Web Consortium (W3C).

What do I need to create HTML?

You don't need any special equipment or software to create HTML. In fact, you probably already have everything you need. Here is what you need:

* Computer
* Text or HTML editor. Most computers already have a text editor and you can easily create HTML files using a text editor. Having said that, there are definite benefits to be gained in downloading an HTML editor.

If you want the best HTML editor, and you don't mind paying money for it, you can't go past Adobe Dreamweaver. Dreamweaver is probably the best HTML editor available, and you can download a trial version for starters.

If you don't have the cash to purchase an editor, you can always download a free one. Examples include SeaMonkey, Coffee Cup (Windows) and TextPad (Windows).

If you don't have an HTML editor, and you don't want to download one just now, a text editor is fine. Most computers already have a text editor. Examples of text editors include Notepad (for Windows), Pico (for Linux), or Simpletext/Text Edit/Text Wrangler (Mac).
* Web Browser. For example, Internet Explorer or Firefox.

Getting Started

Creating a Webpage



1.Create an HTML file

An HTML file is simply a text file saved with an .html or .htm extension (i.e. as opposed to a .txt extension).
1. Open up your computer's normal plain text editor (this will probably be Notepad if you're using Windows or TextEdit if you're using a Mac). You could use a specialized HTML editor such as DreamWeaver or FrontPage if you prefer.
2. Create a new file (if one wasn't already created)
3. Save the file as html_example.html

2.Type some HTML code

Type the following code:

It is easy to implement HTML

3.View the result in your browser

Either...
1. Navigate to your file then double click on it

...OR...
1. Open up your computer's web browser (for example, Internet Explorer, Firefox, Netscape etc).
2. Select File > Open, then click "Browse". A dialogue box will appear prompting you to navigate to the file. Navigate to the file, then select "Open".

HTML Tags

Structure

The HTML html tag is the container that contains all other HTML elements (except for the !DOCTYPE tag which is located before the opening html tag).
All other HTML elements are nested between the opening and tags.It indicates that the text is in HTML

ATTRIBUTES:

version Specifies the HTML DTD version of the document. The version attribute is deprecated - use the !doctype tag instead.
content Specifies the property's value.
scheme Specifies a scheme to use to interpret the property's value (as declared in the content attribute).
http-equiv Used for http response message headers. For example http-equiv can be used to refresh the page or to set a cookie. Values include content-type, expires, refresh and set-cookie.
lang Language code
dir Specifies the direction of the text

The HEAD part of the document provides information about the document. It should not contain text or normal markup.
If a browser encounters such markup, it will assume it has arrived in the BODY section of the document already.

ATTRIBUTES:

profile Specifies the URI/URL of one or more meta data profiles.
lang Language code
dir Specifies the direction of the text

The main body of an HTML document where all of the content is placed. You must use this element and it should be used just once.
It must start immediately after the closing head tag and end directly before the closing html tag.

ATTRIBUTES:

background Specifies the URI/URL of a background image. This attribute is now deprecated.
text Specifies the text color. This attribute is now deprecated.
link Specifies the color of unvisited hyperlink text. This attribute is now deprecated.
vlink Specifies the color of visited hyperlink text. This attribute is now deprecated.
alink Specifies the color of active hyperlink text (i.e. when the user clicks on it). This attribute is now deprecated.
class Document wide identifier.
id Document wide identifier
lang Language code
dir Specifies the direction of the text
title Specifies a title to associate with the element. Many browsers will display this when the cursor hovers over the element (similar to a "tool tip").
style Inline style (CSS)
bgcolor Background color
onload Intrinsic event
onunload Intrinsic event
onclick Intrinsic event
ondbclick Intrinsic event
onmousedown Intrinsic event
onmouseup Intrinsic event
onmouseover Intrinsic event
onmousemove Intrinsic event
onmouseout Intrinsic event
onkeypress Intrinsic event
onkeydown Intrinsic event
onkeyup Intrinsic event

The DIV tag is used to mark up divisions in a document. It can enclose paragraphs, headers and other block elements. Currently, you can only use it to set the default alignment for all enclosed block elements.
Future standards will most likely include more options for DIV.

ATTRIBUTES:

dir Specifies the direction of the text
class Document wide identifier.
id Document wide identifier
lang Language code
title Specifies a title to associate with the element. Many browsers will display this when the cursor hovers over the element (similar to a "tool tip").
style Inline style (CSS)
align Specifies alignment (left, right, center, justify).
onclick Intrinsic event
ondbclick Intrinsic event
onmousedown Intrinsic event
onmouseup Intrinsic event
onmouseover Intrinsic event
onmousemove Intrinsic event
onmouseout Intrinsic event
onkeypress Intrinsic event
onkeydown Intrinsic event
onkeyup Intrinsic event

Meta Information

Document type declaration. This is used to let the browser know what version of HTML you are using.
If you don't use it, or if you get it wrong, the browser will assume you don't know what you're doing and switch to 'quirks mode', which will not render things as they should be.
Apparently it's more 'forgiving' but it actually seems to be quite random and confusing.
Example:

ATTRIBUTES:

NONE