The document provides an overview of key concepts in Java including: - Java is an object-oriented, platform independent language that is simple, secure, and allows for multi-threaded, high performance applications. - Objects have states and behaviors defined by classes. Methods define behaviors and instance variables define states. - Programming conventions like case sensitivity, class/method naming, and file naming are important to follow. - The main() method marks the starting point of a Java program and its modifiers and parameters are explained. - Object-oriented principles like abstraction, encapsulation, inheritance, and polymorphism are discussed at a high-level. - Additional concepts covered include threads, exceptions, constructors, packages, and

1. 13-05-2013Rajavel DRajavel D
Java
Summer Internship – 2013
(Indian Institute of Technology Bombay)

2. Java
 Object-Oriented
 Platform independent
 Simple
 Secure
 Multi-threaded
 High Performance
Rajavel D Java IITB-CSE-Internship 2013

4. Basic terms
 Object - Objects have states and behaviors.
 Class - A class can be defined as a blue print that
describe the behaviors/states that object.
 Methods - A method is basically a behavior.
 Instance Variables - States of an objects, each
object has its unique set of instance variables.
Rajavel D Java IITB-CSE-Internship 2013

5. Keep in Mind
 Case Sensitivity - Hello and hello would have
different meaning in Java.
 Class Names - For all class names the first letter should
be in Upper Case.
Example : class MyFirstJavaClass
 Method Names - All method names should start with a
Lower Case letter and each inner word's first letter
should be in Upper Case.
Example : public void myMethodName()
 Program File Name - Name of the program file should
exactly match the class name.
Rajavel D Java IITB-CSE-Internship 2013

6. Simple Program
class HelloWorldApp {
public static void main(String[] args) {
HelloWorldApp hello = new HelloWorldApp();
hello.sayHello();
}
public void sayHello(){
System.out.println(“Hello”);
}
}
O/P : Hello
Rajavel D Java IITB-CSE-Internship 2013

7. Modifiers and Variables
 Access Modifiers :
 default, public , protected, private
 Non-access Modifiers :
 final, abstract, static, strictfp, synchronized and volatile
 Type of variables in Java:
 Local Variables
 Class Variables (Static Variables)
 Instance Variables (Non static variables)
Rajavel D Java IITB-CSE-Internship 2013

8. public static void main ?
 java program processing starts from the main()
method.
 Public ?
 Static?
 Void?
Rajavel D Java IITB-CSE-Internship 2013

9. Object Oriented Principles
 Abstraction
 Hiding the implementation (abstract class and interface)
 Encapsulation
 Wrapping up of data into single unit. (data hiding)
 Inheritance
 Reusable the properties of existing class
 Polymorphism
 Overloading and Overriding
Rajavel D Java IITB-CSE-Internship 2013

10. Thread
 Create Thread by implements Runnable interface or
extends Thread class
Rajavel D Java IITB-CSE-Internship 2013

11. Exception Handling
 Problem that
arises during the
execution of a
program.
 try{}
 catch{}
 finally{}
Rajavel D Java IITB-CSE-Internship 2013

12. Some important concepts
 Constructor
 Package
 Multithreading
 Synchronized
 This keyword
 finally
Rajavel D Java IITB-CSE-Internship 2013

13. Any Doubts ???
Rajavel D Java IITB-CSE-Internship 2013

14. References
 http://download.oracle.com/javase/tutorial/
 http://www.tutorialspoint.com/java
 www.java2s.com/Tutorial/Java/CatalogJava.h
tm
Rajavel D Java IITB-CSE-Internship 2013