java fundamentals Tutorial

 
 1. Identifers
 2. Reserved words 
 3. Data types 
 4. Literals 
 5. Arrays 
 6. Types of variables
 7. Var-args Methods(1.6 version) 
 8. Main Method
 9. Command line Arguments 
10. Java Coding Standards 
Identfier
Identifiers:
A name of a java programs is known Identifiers. It can be  class Name or Methodname 
or varible Name or label Name

Rules of Identifiers:
Below charecters allowed in java identifier
a-z (Lower Case Charecter (a-z) )
A-Z (Upper Case charecters(A-Z))
0-9 (We are using digits(0-9))
_,$  (Special Symbol(_,$))

Identifiers don't give space
Identfier Example(X)
Identifiers don't start with numbers or digits
99Identfier Example(X)
Reserved words can't used as Identfier 
All the predefined  java class and interface Names are we can use
identifier Names
Example:
class IdentifierExample{
    public static void main(String args[]){
    int String=56;
    int Runnable=78;
    System.out.println(String);
    System.out.println(Runnable);
    }
}
command Prompt 
compilation javac IdentifierExample.java
ExeCution   java IdentifierExample

Java Identifiers are CaseSensitive
Example:
IdentfierExample class Varibales are Three different Variables
class IdentfierExample{
    public static void main(String IdentifiersEx[]){

int identfierOne=10;
int Identfierone=20;
int IdentfieroNe=30;
System.out.println("identfierOne My Value":+identfierOne);
System.out.println("Identfierone My Value":+Identfierone);
System.out.println("IdentfieroNe My Value":+IdentfieroNe);
}

}
open command Prompt
compilation javac IdentifierExample.java
Execution java IdentifierExample

Examples of Identifiers:
example45
45ExXXXX(wrong)
XXXXX45
GayathriHHHHHHH_
HYderabad
HYDERABAD
Hyderabad_secundarabad