seyed0123 / OXDlib

A simple library management system

In the name of GOD

third assignment report

Intrduction

this is a program to manage a simple library where a user can sign up, rent books... and librarians Supervise the actions taken in the library. this program does the user's and librarian's requests and saves book information in itself. it was done through objects and their methods. but don't have a database or work via files.

Design and Implementation

design four principle objects

• User
• Library
• Book
• librarian

now see the objects infromation

1. User :

   attributes	methods	method explanation
   username
   password	Hash password	hashs a string
   	check password	Checks the correctness of the given password
   	set password	sets a new password (required old password)
   books list	get books	prints the list of books that were rented by the user
   	return book	puts the book from book list in the library shlef
   	rent book	puts the book from the library shelf in the person's book list

2. Book :

   attributes	methods	method job
   name	print status	prints all attributes of the book
   author
   ISBN
   year of publish
   number	decreaseBook	decreases number of the book on library shelf
   	increaseBook	increases number of the book on library shelf
   	getNum	returns the number of book on the library shelf

3. librarians

   extended from user

   attributes	methods	method job
   isActive	checkActivity	returns activity status
   	changeActivity	chenges activity status
   	over riding checkPassword	it is also considered activity status

4. library

   attributes	methods	method job
   list of books	addBook	adds a book that isn't in the library with a specified amount on the library shelf
   	removeBook	deletes a book from library
   	searchBook	calls the printStatus() method from the book obj
   	updateBook	updates year of publication of a book
   	doesBookExist	checks if the book is in the library or not
   	decreaseBook	deacreases the amount of book on the library self
   	increaseBook	increases the amount of book on the library self
   	rentBook	checks the adequate conditions and uses the rentBook() method of user obj
   	returnBook	checks the adequate conditions and uses the returnBook() method of user obj
   list of Users	addUser	adds a User that isn't in the library's notebook
   	removeUser	deletes a user from library's notebook
   	searchUser	calls the getBook() method from the user obj
   	updateUser	updated the password by knownig the old password
   	doesUserExist	checks if the user is in the library's notebook or not
   list of Librarians	addLibrarian	adds a Librarian that isn't in the library's notebook
   	removeLibrarian	deletes a Librarian from library's notebook
   	searchLibrarian	checks the activation of the librarian
   	updateLibrarian	change the activation of the librarian
   	doesLibrarianExist	checks if the Librarian is in the library's notebook or not
   	login	checks username and password and return the Specified value for each section

Functions that need explanation

• User.hashPassword : uses the MD5 algorithm to hash passwords that is a secure way to save passwords in the database when the program wants to check the password, hashes an input password and then compares it with the hash string that was stored before.
• library.login :Checks the existence of user and validity of the password.

  return tabel :

  condition	return number
  user with correct password	2
  user with wrong password	1
  librarian with wrong password	-1
  librarian with correct password	-2
  else	0

and handles the value of this return in the main class and then login to user or librarian page

---

• Books are stored in the library in hash map because each one have specefied ISBN code . Search, update, add... books work based on this property of books. This is the case for users and librarians according to their usernames.
• This program use swing GUI to get input and show outputs. this function JOptionpane() creates a new window and does some stuff.
• Implements encapsulation to protect data. so initials almost every variable to private mode so can access them only with that class method. but if initials a variable public it can be changed anywhere and can't check the validity of the data or can be dangerous for important data.
• In each function, for each action, the necessary logical conditions for the inputs are checked first, and then the given command is performed

Testing and Evaluation:

• For testing, this program we set a default librarian and sign in and test all of the functions.
• The result is the program does well for each case but have a little bug so was fixed with no difficulty.
• special case: when a user inputs a non-numeric string when the program wants a numeric string it crashed because of the Integer.parseInt() function so it needed to use this way

  try{} catch{}

to detect crashes and handle them. to solve this problem uses this function getNumberString() , This function ensures that the inputs consist of only numbers

Conclusion:

with the help of this program, we can meet the needs of a library to manage. but this program needs a more beautiful user interface and a strong database or a appropriate server to have a connection between libraries to can be used in practical conditions.