BlueJ Program On Validity Checking On Email Id

In this program user will enter an Email-id and our program will check the validity of the entered email-id. Firstly we have to decide which are the pointes to check while email-id is checked for validity.

Points to be checked for validity

The email-id should have a @ symbol

The email-id should have a ‘.’ (Dot)

The email-id should not have any space

The right part of the email-id, after dot should not have any digit

Codes of the program

import java.io.*;

class Email

{

 String str,str1;

boolean bool=true;

 int i,len;

 char ch;

 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

 public void take() throws Exception

 {

  while(true)

  {

   System.out.println("Enter the mail id:");

   str=br.readLine().trim();

   i=str.indexOf('@');

   if(i==-1)

   {

    System.out.println("Invalid Email Id ('@' symbol missing).");

    continue;

   }

   i=str.indexOf(' ');

   if(i!=-1)

   {

    System.out.println("Invalid Email Id (space is not allowed).");

    continue;

   }

   i=str.indexOf('.');

   if(i==-1)

   {

    System.out.println("Invalid Email Id ('.' missing).");

    continue;

   }

   str1=str.substring(i+1);

   len=str1.length();

   for(i=0;i< len;i++)

   {

    ch=str1.charAt(i);

    if(Character.isDigit(ch))

    break;

   }

   if(i!=len)

   {

    System.out.println("Invalid Email Id (Digit is not permitted in extension part).");

    continue;

   }

bool=false;

 }

    System.out.println("Email Id="+str);

    }

    public static void main(String args[]) throws Exception

    {

     Email ob=new Email();

     ob.take();

     }

     }

Technical analysis of the email-id validity checking program

The email-id is stored in string object ‘str’ and a series of checking is done. All these process is done from within a loop body. indexOf () function searches a character or string from any invoking string string and returns the 1^st occurance location of the character or string in the invoking string if available otherwise returns -1. Using this function the special charaters are checked from the email-id and if not found, the program takes the email-id again from the user. Lastly the extension part of the email-id is checked for existence of digit in it as no digit is permitted in this part. If all these checking paoints are are passed, the email-id is a valid one otherwise there is re-entering option in this program.

Related Post:  BlueJ Programs on String/Sentence