feat: Extract and validate email components (username and domain)

🎯 Purpose:
Implements email string parsing to separate and validate username and domain components
of an email address, with specific validation for Gmail domains.

🧠 Logic:
1. Email Parsing:
   - Locates '@' symbol using indexOf() to split email components
   - Extracts username portion before '@' using substring(0, indexOf('@'))
   - Extracts domain portion after '@' using substring(indexOf('@') + 1)

2. Domain Validation:
   - Performs Gmail-specific domain validation using two approaches:
     a) startsWith("Gmail") to check domain beginning
     b) equalsIgnoreCase("gmail") for case-insensitive exact match
   - Extracts domain name before '.com' for precise validation

🔍 Technical Details:
- Uses String methods: indexOf(), substring(), startsWith(), equalsIgnoreCase()
- Handles email format: "[email protected]"
- Implements case-insensitive domain validation
- Separates domain validation logic from extraction logic

📋 Example:
Input: "[email protected]"
Output:
- Username: "Programmer"
- Domain: "Gmail.com"
- Gmail Validation: true

💡 Note:
This implementation focuses on basic email component extraction and Gmail domain
validation. For production use, consider adding additional validation rules and
error handling for malformed email addresses.

Signed-off-by: Somesh diwan <[email protected]>

Author: Someshdiwan

Section9ArrayAB/Array 2.0/src/StudentChallengeAB.java

@@ -1,7 +1,6 @@
 public class StudentChallengeAB {
     public static void main(String[] args) {
         String str = "[email protected]";
-
         int i = str.indexOf("@");
         String uname = str.substring(0 , i);
         String domainname = str.substring(i+1, str.length());