Java program for IMEI Number

Design a program to accept a fifteen digit number from the user and check whether it is a valid IMEI number or not. For an invalid input, display an appropriate message.

The International Mobile Station Equipment Identity or IMEI is a number, usually unique, to identify mobile phones, as well as some satellite phones. It is usually found printed inside the battery compartment of the phone.

The IMEI number is used by a GSM network to identify valid devices and therefore can be used for stopping a stolen phone from accessing that network.

The IMEI (15 decimal digits: 14 digits plus a check digit) includes information on the origin, model, and serial number of the device.

The IMEI is validated in three steps:

1. Starting from the right, double every other digit (e.g., 7 becomes 14).

2. Sum the digits (e.g., 14 → 1 + 4).

3. Check if the sum is divisible by 10.

Sample output

1. Enter a 15 digit IMEI code : 654122487458946 Output : Sum = 80 Valid IMEI Code

2. Enter a 15 digit IMEI code : 799273987135461 Output : Sum = 79 Invalid IMEI Code

3. Enter a 15 digit IMEI code : 79927398713 Output : Invalid Input

import java.util.*;
class IMEI
{
    int sumDig(int n) 
    {
        int a = 0;
        while(n>0)
        {
            a = a + n%10;
            n = n/10;
        }
        return a;
    }
     
    public static void main(String args[])
    {
        IMEI ob = new IMEI();
        Scanner sc=new Scanner(System.in);         
        System.out.print("Enter a 15 digit IMEI code : ");
        long n = sc.nextLong();         
        String s = Long.toString(n); 
        int l = s.length();         
        if(l!=15) 
            System.out.println("Output : Invalid Input");
        else
        {
            int d = 0, sum = 0;
            for(int i=15; i>=1; i--)
            {
                d = (int)(n%10);
                 
                if(i%2 == 0)
                {
                    d = 2*d; 
                } 
                sum = sum + ob.sumDig(d);                  
                n = n/10;
            }             
            System.out.println("Output : Sum = "+sum);             
            if(sum%10==0)
                System.out.println("Valid IMEI Code");
            else
                System.out.println("Invalid IMEI Code");
        }
    }
}

Enter a 15 digit IMEI code : 654122487458946

Output : Sum = 80

Valid IMEI Code

Enter a 15 digit IMEI code : 799273987135461

Output : Sum = 79

Invalid IMEI Code

Enter a 15 digit IMEI code : 79927398713

Output : Invalid Input