JAVA FUNDAMENTALS

UNIT-I   JAVA FUNDAMENTALS

MODULE-I BASICS OF JAVA

INTRODUCTION TO JAVA

   Java Technology is

*A Programming Language

*A Development Environment

*An Application Environment

*A Deployment Environment

  It is originally developed by James Gosling, Sun Microsystems and now it is developing by oracle. Very first, the java is called as oak.

  It is a language, easy to program because,

  It is eliminating many pitfalls of other language such as pointer, memory management.

  It is fast, secure, and reliable.

  It is platform independent can run in any environment (since java codes are converted into byte codes)

  Before Learning about java you should be aware of the below things..

JVM

            Java Virtual Machine  which means imaginary machine. The java program is compiled by the compiler and converts into byte code (.class files) i.e., machine code then it is verified and run in interpreter.

GARBAGE COLLECTION

To allocate/deallocate memory pointers should be used in other programming languages whereas here there is no need of pointers.

Garbage collection happens automatically during the lifetime of java program, eliminating the need to deallocate the memory and also avoiding the memory leaks

JRE

            Java Runtime Environment, it will load the code then verify the code and finally executes code.

MODULE-II OOPS CONCEPTS

            I hope you are all well known about oops concept. So I skip this chapter.

MODULE-III IDENTIFIER, KEYWORDS AND TYPES

IDENTIFIER:

            Identifier is a name given to a variable, class or method.

            Following are valid identifiers to be used in JAVA:

Username

username

user_name

_username

$username

KEYWORDS:

Abstract	Continue	For	New	Switch
Assert	Default	Goto	Package	Synchronized
Boolean	Do	If	private	This
Break	Double	Implements	Protected	Throw
Byte	Else	Import	Public	Throws
Case	Enum	instanceof	Return	transient
Catch	Extends	Int	Short	Try
Char	Final	Interface	Static	Void
Class	Finally	long	Strictfp	Volatile

DATA TYPES

Eight primitive data types are there in java programming language,

à   Logical- boolean

e.g.: boolean a=true;

à   Textual- char

e.g.: char a=’a’;

à   Integral- byte, short, int and long

à   Floating point- double and float

e.g.:double a=3.1415;

       float a=3.414f

STRING

String is not a primitive data type; it is a class to represent the sequence of the character.

e.g: String a=”hai, how are you”;

MODULE-IV EXPRESSION & FLOW CONTROL

VARIABLES & SCOPE

There are two ways to describe variables:

à   Variable of primitive type

à   Variable of reference type

We can declare variable inside a method or outside a method.

Variable which is defined inside a method is called local variable. Sometime this is also called as automatic, temporary or stacks variables.

Variable defined outside a method are created when the object is constructed using the new abc() call. Variable can be define outside a method in two ways,

à   Using static keyword is called class variable.

à   Without using static keyword is called as instance variable or member variable.

DEFAULT VALUE OF PRIMITIVE TYPES

VARIABLE	VALUE
Byte	0
Short	0
Int	0L
Long	0.0F
Float	0.0D
Double	‘\u0000’
Boolean	False
All reference types	null

OPERATORS

Important types of operators are there in java programming language.

à   Arithmetic Operator (+, -, *, /)

à   Logical Operator (AND (&), OR (|), NOT (!), XOR (^))

à   Short-circuit logical Operator (&&, ||)

*****END*****

UNIT-II JAVA STANDARD EDITION (J2SE)

MODULE I STRUCTURE OF JAVA

Package name i.e., our project name

STRUCTURE

Similar to header file

package javaapplication3;

import java.lang.*; 

public class Main

{

Main function should be within the class

    public static void main(String[] args)

   {

              System.out.println(“hello”);

   }

}

public static void main(String[] args)

public :- The method main() can be accessed by anything including interpreter.

Static :- This keyword tells the compiler that the main() method is used in the class. There is no need of instance to execute the static method.

Void :- it indicates that the main function should not return any value.

String args[] :- the main method is declare with a single parameter “args” which is a type of String array.

COMPILING AND RUNNING THE JAVA PROGRAM

Step1: Type the program in a notepad and save as classname.java and place it in the C:\Program Files\Java\jdk1.7.0_17\bin

Step2 : open the command prompt change the path to C:\Program Files\Java\jdk1.7.0_17\bin and then to compile type javac classname.java, to run type java classname

Step3 : output will be displayed.

Instead running the program in command prompt better we can use IDE like netbeans or eclipse.