GFG Day 14: Mini Project: Library Management System Using Switch Statement in Java

• We have to keep track of all the books, how many copies there are, and whether or not they are available for students to borrow. This makes managing a library an extremely challenging operation.

• Using switch statements, we will construct a simple Java library management system in this post. Adding new books, searching for books, and registering students are just a few of the features we plan to build into this project.

Why Build this Library Management System?

• As we learn Java, we improve our ideas by exploring how to create and administer small applications. This project will help us understand how many of the following items operate:

  • We get to know how to use switch statements for menu-driven applications

  • We get to know how to manage data with classes and objects.

  • We get to know how to implement core features like search, add, and update in a real-world scenario.

Features of the Project

• The library management system will support the following operations which are listed below:

  • Exit Application

  • Add a New Book

  • Upgrade Quantity of a Book

  • Search a Book

  • Show All Books

  • Register Student

  • Show All Registered Students

  • Check Out Book

  • Check-In Book

Let's now understand the project structure of this project.

Project Structure

• Our mini-project will be split into five Java files and each will handle a specific part of the system. The table below demonstrates the file name with their responsibilty.

Note: As per naming conventions in Java, it is good practice to have class initial with uppercase letter still here we are adhering with lowercase for better understanding of the code.

• Before we get into more details, let's first try to understand how the system is put together. As we already know each class is our project has its own work and all these files will work together to make the library management system work more smoothly. We are using different files because we do not want to make the code more complex, by keeping all the files seprate we are increasing the readability of the code.

Project Implementation

Now, let's look at each file and see how it help the whole system work.

1. book.java

• This file will hold the detail about each book including their serial number, Book name, Author name, total quantity and available quantity and the constructor will asks the user to enter these details whenever a new book is added.

// Java Program to Illustrate book Class that
// takes Input from the books and related information

package College;

// Importing required classes
import java.util.Scanner;

// Class
public class book {

    // Class data members
    public int sNo;
    public String bookName;
    public String authorName;
    public int bookQty;
    public int bookQtyCopy;

    // Creating object of Scanner class to
    // read input from users
    Scanner input = new Scanner(System.in);

    // Method
    // To add book details
    public book()
    {
        // Display message for taking input later
        // taking input via
        // nextInt() and nextLine() standard methods
        System.out.println("Enter Serial No of Book:");
        this.sNo = input.nextInt();
        input.nextLine();

        System.out.println("Enter Book Name:");
        this.bookName = input.nextLine();

        System.out.println("Enter Author Name:");
        this.authorName = input.nextLine();

        System.out.println("Enter Quantity of Books:");
        this.bookQty = input.nextInt();
        bookQtyCopy = this.bookQty;
    }
}

2. books.java

// Java Program to Illustrate books class
// To Do all the Operations related to Books such as
// add, check-in, check-out,Valid books,Update books

// Importing required classes
import java.util.Scanner;

// CLass
public class books {

    // Class data members
    book theBooks[] = new book[50];
    public static int count;

    Scanner input = new Scanner(System.in);

    // Method 1
    //  To compare books
    public int compareBookObjects(book b1, book b2)
    {

        // If book name matches
        if (b1.bookName.equalsIgnoreCase(b2.bookName)) {

            // Printing book exists
            System.out.println(
                "Book of this Name Already Exists.");
            return 0;
        }

        // if book serial matches
        if (b1.sNo == b2.sNo) {

            // Print book exists
            System.out.println(
                "Book of this Serial No Already Exists.");

            return 0;
        }
        return 1;
    }

    // Method 2
    // To add book
    public void addBook(book b)
    {

        for (int i = 0; i < count; i++) {

            if (this.compareBookObjects(b, this.theBooks[i])
                == 0)
                return;
        }

        if (count < 50) {

            theBooks[count] = b;
            count++;
        }
        else {

            System.out.println(
                "No Space to Add More Books.");
        }
    }

    // Method 3
    // To search book by serial number
    public void searchBySno()
    {

        // Display message
        System.out.println(
            "\t\t\t\tSEARCH BY SERIAL NUMBER\n");

        // Class data members
        int sNo;
        System.out.println("Enter Serial No of Book:");
        sNo = input.nextInt();

        int flag = 0;
        System.out.println(
            "S.No\t\tName\t\tAuthor\t\tAvailable Qty\t\tTotal Qty");

        for (int i = 0; i < count; i++) {
            if (sNo == theBooks[i].sNo) {
                System.out.println(
                    theBooks[i].sNo + "\t\t"
                    + theBooks[i].bookName + "\t\t"
                    + theBooks[i].authorName + "\t\t"
                    + theBooks[i].bookQtyCopy + "\t\t"
                    + theBooks[i].bookQty);
                flag++;
                return;
            }
        }
        if (flag == 0)
            System.out.println("No Book for Serial No "
                               + sNo + " Found.");
    }

    // Method 4
    // To search author by name
    public void searchByAuthorName()
    {

        // Display message
        System.out.println(
            "\t\t\t\tSEARCH BY AUTHOR'S NAME");

        input.nextLine();

        System.out.println("Enter Author Name:");
        String authorName = input.nextLine();

        int flag = 0;

        System.out.println(
            "S.No\t\tName\t\tAuthor\t\tAvailable Qty\t\tTotal Qty");

        for (int i = 0; i < count; i++) {

            // if author matches any of its book
            if (authorName.equalsIgnoreCase(
                    theBooks[i].authorName)) {

                // Print below corresponding credentials
                System.out.println(
                    theBooks[i].sNo + "\t\t"
                    + theBooks[i].bookName + "\t\t"
                    + theBooks[i].authorName + "\t\t"
                    + theBooks[i].bookQtyCopy + "\t\t"
                    + theBooks[i].bookQty);
                flag++;
            }
        }

        // Else no book matches for author
        if (flag == 0)
            System.out.println("No Books of " + authorName
                               + " Found.");
    }

    // Method 5
    // To display all books
    public void showAllBooks()
    {

        System.out.println("\t\t\t\tSHOWING ALL BOOKS\n");
        System.out.println(
            "S.No\t\tName\t\tAuthor\t\tAvailable Qty\t\tTotal Qty");

        for (int i = 0; i < count; i++) {

            System.out.println(
                theBooks[i].sNo + "\t\t"
                + theBooks[i].bookName + "\t\t"
                + theBooks[i].authorName + "\t\t"
                + theBooks[i].bookQtyCopy + "\t\t"
                + theBooks[i].bookQty);
        }
    }

    // Method 6
    // To edit the book
    public void upgradeBookQty()
    {

        System.out.println(
            "\t\t\t\tUPGRADE QUANTITY OF A BOOK\n");
        System.out.println("Enter Serial No of Book");

        int sNo = input.nextInt();

        for (int i = 0; i < count; i++) {

            if (sNo == theBooks[i].sNo) {

                // Display message
                System.out.println(
                    "Enter No of Books to be Added:");

                int addingQty = input.nextInt();
                theBooks[i].bookQty += addingQty;
                theBooks[i].bookQtyCopy += addingQty;

                return;
            }
        }
    }

    // Method 7
    // To create menu
    public void dispMenu()
    {

        // Displaying menu
        System.out.println(
            "----------------------------------------------------------------------------------------------------------");
        System.out.println("Press 1 to Add new Book.");
        System.out.println("Press 0 to Exit Application.");
        System.out.println(
            "Press 2 to Upgrade Quantity of a Book.");
        System.out.println("Press 3 to Search a Book.");
        System.out.println("Press 4 to Show All Books.");
        System.out.println("Press 5 to Register Student.");
        System.out.println(
            "Press 6 to Show All Registered Students.");
        System.out.println("Press 7 to Check Out Book. ");
        System.out.println("Press 8 to Check In Book");
        System.out.println(
            "-------------------------------------------------------------------------------------------------------");
    }

    // Method 8
    // To search the library
    public int isAvailable(int sNo)
    {

        for (int i = 0; i < count; i++) {
            if (sNo == theBooks[i].sNo) {
                if (theBooks[i].bookQtyCopy > 0) {

                    System.out.println(
                        "Book is Available.");
                    return i;
                }
                System.out.println("Book is Unavailable");
                return -1;
            }
        }

        System.out.println("No Book of Serial Number "
                           + " Available in Library.");
        return -1;
    }

    // Method 9
    // To remove the book from the library
    public book checkOutBook()
    {

        System.out.println(
            "Enter Serial No of Book to be Checked Out.");
        int sNo = input.nextInt();

        int bookIndex = isAvailable(sNo);

        if (bookIndex != -1) {
            theBooks[bookIndex].bookQtyCopy--;
            return theBooks[bookIndex];
        }
        return null;
    }

    // Method 10
    // To add the Book to the Library
    public void checkInBook(book b)
    {
        for (int i = 0; i < count; i++) {
            if (b.equals(theBooks[i])) {
                theBooks[i].bookQtyCopy++;
                return;
            }
        }
    }
}

3. student.java

• This class represents a student in the library system. Each student has a name, registration number and each student can borrow upto 3 books at a time which are stored in an array and whenver a new student is added into the system, the program will asks for detials with the help of a constructor.

// Java Program to Illustrate Student Class
// to take Input from the student and related Information

// Importing required classes
import java.util.Scanner;

// Class
public class student {

    // Class member variables
    String studentName;
    String regNum;

    book borrowedBooks[] = new book[3];
    public int booksCount = 0;

    // Creating object of Scanner class to
    // take input from user
    Scanner input = new Scanner(System.in);

    // Constructor
    public student()
    {
        // Print statement
        System.out.println("Enter Student Name:");

        // This keywords refers to current instance
        this.studentName = input.nextLine();

        // Print statement
        System.out.println("Enter Registration Number:");
        this.regNum = input.nextLine();
    }
}

4. students.java

• This class will keep track of all the student registered in the library. It adds new students only when the registration number is unique. We can see a list of registered students as well, before a student borrow or returned a book this class will always check that this particular student is registered in the system or not. It also handles the process of student borrowing and returning book.

// Java Program to Illustrate students Class
// To Do all the Operations related to students:
// add Students,check-in books,check out books,ValidStudent

// Importing required classes
import java.util.Scanner;

// Class
public class students {

    // Creating objects of Scanner and students class
    Scanner input = new Scanner(System.in);
    student theStudents[] = new student[50];

    public static int count = 0;

    // Method 1
    // To add books
    public void addStudent(student s)
    {
        for (int i = 0; i < count; i++) {

            if (s.regNum.equalsIgnoreCase(
                    theStudents[i].regNum)) {

                // Print statement
                System.out.println(
                    "Student of Reg Num " + s.regNum
                    + " is Already Registered.");

                return;
            }
        }

        if (count <= 50) {
            theStudents[count] = s;
            count++;
        }
    }

    // Method 2
    // Displaying all students
    public void showAllStudents()
    {
        // Printing student name and
        // corresponding registered number
        System.out.println("Student Name\t\tReg Number");
        for (int i = 0; i < count; i++) {

            System.out.println(theStudents[i].studentName
                               + "\t\t"
                               + theStudents[i].regNum);
        }
    }

    // Method 3
    // To check the Student
    public int isStudent()
    {
        // Display message only
        System.out.println("Enter Reg Number:");

        String regNum = input.nextLine();

        for (int i = 0; i < count; i++) {

            if (theStudents[i].regNum.equalsIgnoreCase(
                    regNum)) {
                return i;
            }
        }

        // Print statements
        System.out.println("Student is not Registered.");
        System.out.println("Get Registered First.");

        return -1;
    }

    // Method 4
    // To remove the book
    public void checkOutBook(books book)
    {
        int studentIndex = this.isStudent();

        if (studentIndex != -1) {
            System.out.println("checking out");

            book.showAllBooks();
            book b = book.checkOutBook();

            System.out.println("checking out");
            if (b != null) {

                if (theStudents[studentIndex].booksCount
                    <= 3) {

                    System.out.println("adding book");
                    theStudents[studentIndex].borrowedBooks
                        [theStudents[studentIndex]
                             .booksCount]
                        = b;
                    theStudents[studentIndex].booksCount++;

                    return;
                }
                else {

                    System.out.println(
                        "Student Can not Borrow more than 3 Books.");
                    return;
                }
            }
            System.out.println("Book is not Available.");
        }
    }

    // Method 5
    // To add the book
    public void checkInBook(books book)
    {
        int studentIndex = this.isStudent();
        if (studentIndex != -1) {

            // Printing credentials corresponding to student
            System.out.println(
                "S.No\t\t\tBook Name\t\t\tAuthor Name");

            student s = theStudents[studentIndex];

            for (int i = 0; i < s.booksCount; i++) {

                System.out.println(
                    s.borrowedBooks[i].sNo + "\t\t\t"
                    + s.borrowedBooks[i].bookName + "\t\t\t"
                    + s.borrowedBooks[i].authorName);
            }

            // Display message only
            System.out.println(
                "Enter Serial Number of Book to be Checked In:");

            int sNo = input.nextInt();

            for (int i = 0; i < s.booksCount; i++) {
                if (sNo == s.borrowedBooks[i].sNo) {
                    book.checkInBook(s.borrowedBooks[i]);
                    s.borrowedBooks[i] = null;

                    return;
                }
            }

            System.out.println("Book of Serial No " + sNo
                               + "not Found");
        }
    }
}

5. Library.java

• This is the main class of our project where everything comes together. This class shows a welcome message and a menu of options to the user. Using a do-while loop and a switch statement, it lets the user choose what they want to do and then runs the right actions based on their choice. This class calls methods from the books and students classes to handle tasks like adding books, registering students, or checking out books. It even has a nested switch to let users search for books by either serial number or author name.

// Java Program to Illustrate Application CLass
// To Create The Menu For the Program

// Importing required classes
import java.util.Scanner;

// Class
public class Library {

    // Main driver method
    public static void main(String[] args)
    {
        // Creating object of Scanner class
        // to take input from user
        Scanner input = new Scanner(System.in);

        // Displaying menu
        System.out.println(
            "********************Welcome to the GFG Library!********************");
        System.out.println(
            "                  Select From The Following Options:               ");
        System.out.println(
            "**********************************************************************");

        // Creating object of book class
        books ob = new books();
        // Creating object of students class
        students obStudent = new students();

        int choice;
        int searchChoice;

        // Creating menu
        // using do-while loop
        do {

            ob.dispMenu();
            choice = input.nextInt();

            // Switch case
            switch (choice) {

                // Case
            case 1:
                book b = new book();
                ob.addBook(b);
                break;

                // Case
            case 2:
                ob.upgradeBookQty();
                break;

            // Case
            case 3:

                System.out.println(
                    " press 1 to Search with Book Serial No.");
                System.out.println(
                    " Press 2 to Search with Book's Author Name.");
                searchChoice = input.nextInt();

                // Nested switch
                switch (searchChoice) {

                    // Case
                case 1:
                    ob.searchBySno();
                    break;

                    // Case
                case 2:
                    ob.searchByAuthorName();
                }
                break;

                // Case
            case 4:
                ob.showAllBooks();
                break;

                // Case
            case 5:
                student s = new student();
                obStudent.addStudent(s);
                break;

                // Case
            case 6:
                obStudent.showAllStudents();
                break;

                // Case
            case 7:
                obStudent.checkOutBook(ob);
                break;

                // Case
            case 8:
                obStudent.checkInBook(ob);
                break;

                // Default case that will execute for sure
                // if above cases does not match
            default:

                // Print statement
                System.out.println("ENTER BETWEEN 0 TO 8.");
            }

        }

        // Checking condition at last where we are
        // checking case entered value is not zero
        while (choice != 0);
    }
}

Output

1. Add Book

2. Register Student:

Rent Book /Check Out Book

3. Show All Books:

4. Return The Book/Check-In Book:

5. Update the Quantity of the Book:

6. Search the Book:

7. Show All the Registered Student:

---

Happy Learning

Thanks For Reading! :)

SriParthu 💝💥