Question

Assignment 2: Exceptions

Mr. Mike wants to check whether the student number and GSM number entered by the student to register for attending a conference is valid or not.

Write a program in Java to read the Student ID and GSM Number of a student. If the Student ID does not start with the characters ST or if the Mobile Number does not contain exactly 8 digits, throw a user defined exception InvalidDetailsException.

If the Mobile Number contains any character other than a digit, throw a NumberFormatException. If the student ID contains any special character other than digits and alphabets, throw a NoSuchElementException. If the details entered are valid, display the message ”Correct details are entered!!!” otherwise display “Entered invalid details!!!!”

Sample Test case:

Enter Student Number:

ST1402

Enter Student GSM Number:

98989898

Output:

”Correct details are entered!!!”

===========================================

Enter Student Number:

1402ST

Enter Student GSM Number:

999898998

Output:

Student Id is invalid !!!

Student GSM number is invalid !!!

“Entered invalid details!!!!”

Answer 1

//Required code is as follows.

import java.util.Scanner;

// user defined exception InvalidDetailsException

class InvalidDetailsException extends Exception
{
   public InvalidDetailsException(String s)
   {
       // call constructor of parent Exception.
       super(s);
   }
}

class exception
{
   public static void main(String args[])
   {
       Scanner sc = new Scanner(System.in);
       String studentNumber = "";
       String gsmNumber = "";
       boolean error = false;
       try
       {
           System.out.println("Enter Student Number:");
           studentNumber = sc.next();
           if(studentNumber.charAt(0)!='S' || studentNumber.charAt(1)!='T')
               throw new InvalidDetailsException("Student Id is invalid !!!");
       }
       catch(InvalidDetailsException e)
       {
           error = true;
           System.out.println(e.getMessage());
       }
       try
       {          
           System.out.println("Enter Student GSM Number:");
           gsmNumber = sc.next();
          
           if(gsmNumber.length()!=8)
               throw new InvalidDetailsException("Student GSM number is invalid !!!");
       }

       catch(InvalidDetailsException e)
       {
           error = true;
           System.out.println(e.getMessage());
       }

       try
       {
           for(int i=0;i<studentNumber.length();i++)
           {
               if (!((studentNumber.charAt(i)>='a' && studentNumber.charAt(i)<='z') || (studentNumber.charAt(i)>='A' && studentNumber.charAt(i)<='Z') || (studentNumber.charAt(i)>='0' && studentNumber.charAt(i)<='9')))
               {
                   throw new NoSuchFieldException();
               }
           }
       }

       catch(NoSuchFieldException e)
       {
           error = true;
           System.out.println(e.getMessage());
       }

       try
       {
           for(int i=0;i<8;i++)
           {
               if(!(gsmNumber.charAt(i)>='0' && gsmNumber.charAt(i)<='9'))
               {
                   throw new NumberFormatException();
               }
           }
       }      

       catch(NumberFormatException e)
       {
           error = true;
           System.out.println(e.getMessage());
       }

       if(error)
           System.out.println("Entered invalid details!!!!");
       else
           System.out.println("Correct details are entered!!!");

   }
}

//Refer above image for sample output

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