String Indexing:
================
We can use an index (positive values) to access the individual characters of the string.
Syntax:
	string-object-name[index-value]; ==> Not avaiable

Note:
=====
indexing notation "[]" is not supported for the strings

Acquiring the Part of string:
=============================
part of string ==> sub-string

substring():
============
==> can be used to access or to acquire the part of the string.
==> in two ways:
	1) substring(startIndex)
	2) substring(startIndex, endIndex)
Syntax:
	string-object.substring()

class StringIndexing{
    public static void main(String[] args)
    {
        String s1 = "Java Programming";
        
        System.out.println(s1);
        System.out.println(s1.substring(5));
        System.out.println(s1.substring(0,4));
    }
}
=====================================

String Comparison:
==================
	1) using == (equal operator)
	2) equals()
	3) equalsIgnoreCase()
	4) compareTo()

1) using == (equal operator)
=============================

class StringComparison{
    public static void main(String[] args)
    {
        String s1 = "java"; // string literal
        String s2 = new String("java"); // string object
        
        // == : compare whether two strings pointing to the same object or not
        System.out.println(s1 == s2);
        
        String s3 = s1;
        String s4 = s2;
        
        System.out.println(s1 == s3);
        System.out.println(s2 == s4);
    }
}
==================================
equals():
=========
==> pre-defined method 
	use to compare whether two strings are with same data or not.
Syntax:
	string-object1.equals(string-object2)

class StringComparison{
    public static void main(String[] args)
    {
        String s1 = "Java";
        String s2 = s1;
        String s3 = new String("Java");
        String s4 = s3;
        String s5 = null;
        
        System.out.println(s1.equals(s2));
        System.out.println(s3.equals(s4));
        System.out.println(s1.equals(s3));
        System.out.println(s1.equals(s5));
    }
}
======================================
3) equalsIgnoreCase()
=====================
s1 = "java" 
s2 = "Java"
s3 = "JAVA"
s1.equalsIgnoreCase(s2) ==> true

==> used to compare the internal content of two strings are same or not by ignoring the case.
Syntax:
	string1.equalsIgnoreCase(string2)

class StringComparison{
    public static void main(String[] args)
    {
        String s1 = "Java Programming Language";
        String s2 = new String("java programming language");
        
        System.out.println(s1 == s2);
        System.out.println(s1.equals(s2));
        System.out.println(s1.equalsIgnoreCase(s2));
    }
}
===================================
4) compareTo():
===============
	return an integer value:
		0 ==> both strings are same
		else ==> both strings are not same
Syntax:
	string1.compareTo(string2)

class StringComparison{
    public static void main(String[] args)
    {
        String s1 = "java";
        String s2 = new String("java");
        String s3 = "Java";
        String s4 = "python";
        
        System.out.println(s1.compareTo(s2));
        System.out.println(s1.compareTo(s3));
        System.out.println(s3.compareTo(s2));
        System.out.println(s1.compareTo(s4));
    }
}
==========================================
String Length:
==============

length():
=========
==> use to find the size or the string
or
==> to count the number of characters in a string, we can use length() method.
Syntax:
	string-object-name.length()

class StringComparison{
    public static void main(String[] args)
    {
        String s1 = new String("Java Programming Language");
        System.out.println("The Size of the String = "+s1.length());
    }
}
=======================================
Mutable Vs Immutable:
=====================
Immutable:
==========
The object which does not allowed for the modification after the definition are called as "Immutable Objects".

Mutable:
========
The Object which does allowed for the modification after the definition are called as "Mutable Objects".

Strings Vs Immutable:
=====================
concat():
=========
	==> string concatenation
	==> joining of two strings into one is called as "string concatenation".
	Syntax:
		string1.concat(string2);
ex: s1 = "java"
s2 = "program"
concat() ==> "javaprogram"

class StringImmutability{
    public static void main(String[] args)
    {
        String s1 = "Java";
        String s2 = "Programs";
        
        System.out.println("Before the Concatenation:");
        System.out.println(s1);
        System.out.println(s2);
        
        // String s3 = s1.concat(s2);
        s1 = s1.concat(s2);
        
        System.out.println("After the Concatenation:");
        System.out.println(s1);
        System.out.println(s2);
        // System.out.println(s3);
    }
}
===============================
toUpperCase():
==============
	==> can use to convert the string from lower case to upper case.
Syntax:
	string-object.toUpperCase()

toLowerCase():
==============
	==> can use to convert the string from upper case to lower case.
	Syntax:
		string-object.toLowerCase()

class StringImmutability{
    public static void main(String[] args)
    {
        String s1 = "java programming";
        String s2 = "PYTHON";
        
        System.out.println("Before to change:");
        System.out.println(s1);
        
        s1.toUpperCase();
        
        System.out.println("After the change:");
        System.out.println(s1);
        
        s1 = s1.toUpperCase();
        System.out.println(s1);
        
        System.out.println("s2 = "+s2);
        
        s2 = s2.toLowerCase();
        
        System.out.println("s2 = "+s2);
    }
}

============================
class StringImmutability{
    public static void main(String[] args)
    {
       String username = "Ravi123";
       String password = "ravi@123";
       
       if((username.equals("Ravi@123")) && (password.equals("ravi@123")))
       {
           System.out.println("Login Successful");
       }
       else
       {
           System.out.println("Login Fail");
       }
    }
}