Java regular expression program to validate an email including blank field valid as well

Following regular expression matches given e-mail id including the blank input −

^([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6})?$

Where,

• ^ matches the starting of the sentence.

• [a-zA-Z0-9._%+-] matches one character from English alphabet (both cases), digits, "+", "_", ".","" and, "-" before the @ symbol.

• + indicates the repetition of the above mentioned set of characters one or more times.

• @ matches itself

• [a-zA-Z0-9.-] matches one character from English alphabet (both cases), digits, "." and "-" after the @ symbol

• \.[a-zA-Z]{2,6} two to 6 letter for email domain after "."

• $ indicates the end of the sentence

Example 1

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class SampleTest {
   public static void main( String args[] ) {
      String regex = "^([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6})?$";
      //Reading input from user
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter your name: ");
      String name = sc.nextLine();
      System.out.println("Enter your e-mail: ");
      String e_mail = sc.nextLine();
      System.out.println("Enter your age: ");
      int age = sc.nextInt();
      //Instantiating the Pattern class
      Pattern pattern = Pattern.compile(regex);
      //Instantiating the Matcher class
      Matcher matcher = pattern.matcher(e_mail);
      //verifying whether a match occurred
      if(matcher.find()) {
         System.out.println("e-mail value accepted");
      } else {
         System.out.println("e-mail not value accepted");
      }
   }
}

Output1

Enter your name:
krishna
Enter your e-mail:
Enter your age:
20
e-mail value accepted

Output 2

Enter your name:
Rajeev
Enter your e-mail:
[email protected]
Enter your age:
25
e-mail value accepted

Example 2

import java.util.Scanner;
public class Example {
   public static void main(String args[]) {
      //Reading String from user
      System.out.println("Enter email address: ");
      Scanner sc = new Scanner(System.in);
      String e_mail = sc.nextLine();
      //Regular expression
      String regex = "^([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6})?$";
      boolean result = e_mail.matches(regex);
      if(result) {
         System.out.println("Valid match");
      } else {
         System.out.println("Invalid match");
      }
   }
}

Output 1

Enter email address:
[email protected]
Valid match

Output 2

Enter email address:
Valid match