This document provides an introduction and overview of Java applications, including: - A brief history of Java's development starting in 1990s. - The objectives and topics covered include introductions, history, architecture, security and a sample program. - Java was designed to be a platform-independent language that can create applications running on a single computer or distributed network.

1. Introduction
to Java Applications
By:
Ajit Vijayee Yadav

2. OBJECTIVES
 Introduction
 History
 Need for Java
 The Evolution of Java
 Characteristics of Java
 Java Architecture
 How Java Works
 Java Architectural Security
 Sample Program in Java
 Conclusions
 Reference
2

3. Introduction to Java
 James Gosling-1995
 Java is an OOP language that was designed to meet the
need for the platform-independent language. Java is
used to create application that can run on a single
computer as well as a distributed network. Java is used
to develop a stand-alone and Internet-based
applications.
 The Java programs works on any type of compatible
device that supports Java.

4. History of Java
 Java programming language was originally developed
by Sun Microsystems, which was initiated by James
Gosling and released in 1995 .
 As of December 08 the latest release of the Java
Standard Edition is 6 (J2SE).
 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

5. Needs for Java
• Java can be used to write variety of application
o Applications that use CUI
o Application that use GUI
o Applets
o Servlets
o Packages

6. The Evolution of Java
Year
1990
1991
1993
Development
Sun Microsystems developed software to
manipulate electronic devices.
A new language named Oak was introduced
using the most popular object-oriented
language C++.
World Wide Web(WWW) appeared on the
Internet that transformed the text-based
Internet into graphical Internet.

7. 1994
1995
1996
The Sun Microsystems team developed a Web
browser called HotJava to locate and run
applets programs on Internet.
Oak was rename as Java.
Java was established as an object-oriented
language.

8. Characteristics of Java
 Java Applets
 Java’s Magic
 Servlets : Java on the server side
Other characteristics of Java
Simple
Secure
Portable
Object Oriented
Robust etc.

9. Java Architecture
 Various components of Java architecture are:
Java programming language and class file
JVM
Java Application Programming Interface (API)

10. The Java Programming
Environment

11. How Java Works
 Java's platform independence is achieved by the use of
the Java Virtual Machine
 A Java program consists of one or more files with a
.java extension
 The .class file contains Java bytecode.
 Bytecode is like machine language, but it is intended
for the Java Virtual Machine not a specific chip such as
a Pentium or PowerPC chip
 Some people refer to the interpreter as "The Java
Virtual Machine" (JVM)

12. Java Architectural Security
 The Java architecture also consist of few security
features that make Java a secure programming
language. The architecture consists of the following
security features:
Compiler level security
Bytecode verifier
Class loader
Sandbox model

13. Sample Program in Java
1.//Text-printing program.
2.
3. Public class Welcome
4.{
5.
//main method begins execution of java
application
6.
Public static void main(String arg[ ])
7.
{
8.
System.out.println(“welcome to Java
Programming”);

14. 9.
}//end method main
10.
}//end class Welcome
Output :
Welcome to Java Programming

15. Comments
 Comments start with: //
 Comments ignored during program execution
 Document and describe code
 Provides code readability
 Traditional comments: /* ... */
/* This is a traditional
comment. It can be
split over many lines */
 Another line of comments
 Note: line numbers not part of program, added for reference

16. First Program in Java: Printing a Line of Text
(Cont.)
3
 Blank line


4
Makes program more readable
Blank lines, spaces, and tabs are white-space characters
 Ignored by compiler
public class Welcome1
 Begins class declaration for class Welcome1



Every Java program has at least one user-defined class
Keyword: words reserved for use by Java
 class keyword followed by class name
Naming classes: capitalize every word
 SampleClassName
16

17. First Program in Java: Printing a Line of Text
(Cont.)
4
public class Welcome1
 Java identifier




Series of characters consisting of letters, digits,
underscores ( _ ) and dollar signs ( $ )
Does not begin with a digit, has no spaces
Examples: Welcome1, $value, _value, button7
 7button is invalid
Java is case sensitive (capitalization matters)
 a1 and A1 are different
 In chapters 2 to 7, start each class with public class

Details of this covered later
17

18. First Program in Java: Printing a Line of Text
(Cont.)
4
public class Welcome1
 Saving files


5
File name must be class name with .java extension
Welcome1.java
{
 Left brace {


Begins body of every class
Right brace ends declarations (line 13)
18

19. First Program in Java: Printing a Line of Text
(Cont.)
7
public static void main( String args[] )
 Part of every Java application


Applications begin executing at main
 Parentheses indicate main is a method (Ch. 3 and 6)
 Java applications contain one or more methods
Exactly one method must be called main
 Methods can perform tasks and return information


8
void means main returns no information
For now, mimic main's first line
{
 Left brace begins body of method declaration

Ended by right brace } (line 11)
19

20. First Program in Java: Printing a Line of Text
(Cont.)
System.out.println( "Welcome to Java Programming!" );
9
 Instructs computer to perform an action


Prints string of characters
 String – series of characters inside double quotes
White-spaces in strings are not ignored by compiler
 System.out


Standard output object
Print to command window (i.e., MS-DOS prompt)
 Method System.out.println

Displays line of text
 This line known as a statement

Statements must end with semicolon ;
20

21. First Program in Java: Printing a Line of Text
(Cont.)
11
} // end method main
 Ends method declaration
13
} // end class Welcome1
 Ends class declaration
 Can add comments to keep track of ending braces
21

22. First Program in Java: Printing a Line of Text
(Cont.)
 Executing a program
 Type java Welcome1




Launches JVM
JVM loads .class file for class Welcome1
.class extension omitted from command
JVM calls method main
22

23. Conclusion
Finally conclusion of this training is great .which is
helping for the basic knowledge about robotics and
own analog design .This training is six week .which is
good and impressive content in the training to help in
my success of Robotics career

24. REFERENCES
1.Internet (Wiki.com)
2.Teacher and friends
3.Books (Reference to Java And PHP )
4.NIIT Student Guide