Click on the attachment link below to download the Diagram file.

1. Library – Librarian Relationship:

The “Library” class contains a “librarian” attribute, indicating that a library has a librarian.

2. Library – Staff Relationship:

The “Library” class has a “staffMembers” attribute, indicating a composition relationship with the “Staff” class. This suggests that the staff members are part of the library.

3. Library – Book Relationship:

The “Library” class has a “books” attribute, indicating a composition relationship with the “Book” class. This suggests that the books are part of the library’s collection.

4. Librarian – Book Relationship:

The “Librarian” class has a method “issueBook(Book)” and is expected to interact with books, representing an association.

5. Member – Book Relationship:

The “Member” class has methods “borrowBook(Book)” and “returnBook(Book),” indicating an association with books.

6. Member – Subject Relationship:

The “Member” class may have an interest in certain subjects, represented by the “Subject” class. This relationship is not explicitly shown in the model, but it can be inferred based on the “Subject” class’s association with books.

7. Book – Subject Relationship:

The “Book” class has a “subject” attribute, representing an association with the “Subject” class. This indicates that a book is related to a particular subject.

Use Offline IDE like Sublime, VScode , IntelliJ to run this code.

package sikshapath; //create your own package
import java.util.*;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Scanner;

class EmailId
{

    String domainID,username,password;

    EmailId()
    {
        domainID="K7";
        username="K";
        password="constructc000";
    }

    EmailId(String user,String pass,String domID)
    {
        domainID=domID;
        username=user;
        password=pass;
    }

    public static void main(String[] args) {
        String user,pass, domID;
        int p=-1,up=-1,u=-1,d=-1;

        EmailId obj=new EmailId();

        Scanner sc= new Scanner(System.in);
        System.out.println("Enter username: ");
        user=sc.nextLine();
        System.out.println("\nEnter password: ");
        pass=sc.nextLine();
        System.out.println("\nEnter Domain ID: ");
        domID=sc.nextLine();
        System.out.println("Enter a date in dd/mm/yyyy format :");
        String date = sc.next();

        EmailId obj1=new EmailId(user,pass,domID);

        if((obj.username).equals(obj1.username))
        {
            u=1;
            if(obj.password.equals(obj1.password))
            {
                up=1;
            }
            else
            {
                p=0;
            }
        }
        else
        {
            u=0;
        }

        if(dateValidation(date)==true)
            d=1;
        else
            d=0;

        if(d==1)
        {
            if(u==0)
            {

                try{
                    throw new InvalidUsernameException(user);
                }

                catch (Exception e) {
                    System.out.println(e) ;
                }
            }

            if (p==0){
                {
                    try{

                        throw new InvalidPasswordException(pass);
                    }
                    catch (Exception e) {
                        System.out.println(e) ;
                    }
                }
            }

            if(up==1)
            {
                System.out.println("Valid email id");
            }
        }
        else{
            System.out.println("Not a Valid email id");
        }

    }

    public static boolean dateValidation(String date)
    {
        boolean status = false;

        if (checkDate(date)) {
            DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
            dateFormat.setLenient(false);
            try {
                dateFormat.parse(date);
                status = true;
            } catch (Exception e) {
                status = false;
            }
        }
        return status;
    }

    static boolean checkDate(String date) {
        String pattern = "(0?[1-9]|[12][0-9]|3[01])\\/(0?[1-9]|1[0-2])\\/([0-9]{4})";
        boolean flag = false;
        if (date.matches(pattern)) {
            flag = true;
        }
        return flag;

    }



}

class InvalidUsernameException extends Exception{
    String num1;
    InvalidUsernameException(String num2) {
        num1=num2;
    }
    public String toString(){
        return ("exception in thread ‘main’ InvalidUsernameException: Username: "+ num1 + " doesn’t match") ;
    }
}

class InvalidPasswordException extends Exception{
    String num1;
    InvalidPasswordException(String num2) {
        num1=num2;
    }
    public String toString(){
        return ("exception in thread ‘main’ InvalidPasswordException: Username: "+ num1 + " doesn’t match") ;
    }
}