Virtual-Library

// A class to represent a generic information carrier
class Carrier {
  // Private instance variables to store the common attributes of all carriers
  private String type; // The type of the carrier (book, magazine, etc.)
  private String author; // The author of the carrier
  private String title; // The title of the carrier
  private int year; // The year of publication of the carrier
  private boolean status; // The status of the carrier (free or busy)

  // A constructor that takes all the parameters and assigns them to the instance variables
  public Carrier(String type, String author, String title, int year, boolean status) {
    this.type = type;
    this.author = author;
    this.title = title;
    this.year = year;
    this.status = status;
  }

  // A constructor that takes no parameters and assigns default values to the instance variables
  public Carrier() {
    this.type = "Unknown";
    this.author = "Unknown";
    this.title = "Unknown";
    this.year = 0;
    this.status = true;
  }

  // Public getters and setters for the private instance variables
  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }

  public String getAuthor() {
    return author;
  }

  public void setAuthor(String author) {
    this.author = author;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }

  public int getYear() {
    return year;
  }

  public void setYear(int year) {
    // Input validation: the year should be positive and not greater than the current year
    if (year > 0 && year <= java.time.Year.now().getValue()) {
      this.year = year;
    } else {
      System.out.println("Invalid year");
    }
  }

  public boolean getStatus() {
    return status;
  }

  public void setStatus(boolean status) {
    this.status = status;
  }

  // A method to display the details of the carrier
  public void display() {
    System.out.println("Type: " + type);
    System.out.println("Author: " + author);
    System.out.println("Title: " + title);
    System.out.println("Year: " + year);
    System.out.println("Status: " + (status ? "Free" : "Busy"));
    System.out.println();
  }
}

// A class to represent a book as a subclass of Carrier
class Book extends Carrier {
  // Private instance variable to store the number of pages of the book
  private int pages;

  // A constructor that takes all the parameters and passes them to the superclass constructor
  // and assigns the pages to the instance variable
  public Book(String author, String title, int year, boolean status, int pages) {
    super("Book", author, title, year, status);
    this.pages = pages;
  }

  // A constructor that takes no parameters and passes default values to the superclass constructor
  // and assigns a default value to the pages
  public Book() {
    super("Book", "Unknown", "Unknown", 0, true);
    this.pages = 0;
  }

  // A public getter and setter for the private instance variable
  public int getPages() {
    return pages;
  }

  public void setPages(int pages) {
    // Input validation: the pages should be positive
    if (pages > 0) {
      this.pages = pages;
    } else {
      System.out.println("Invalid pages");
    }
//continue with the code
 }

  // A method to override the display method of the superclass and add the pages
  @Override
  public void display() {
    super.display();
    System.out.println("Pages: " + pages);
    System.out.println();
  }
}

// A class to represent a virtual library that contains an array of carriers
class Library {
  // Private instance variable to store the array of carriers
  private Carrier[] carriers;

  // A constructor that takes the size of the array and creates a new array of carriers
  public Library(int size) {
    carriers = new Carrier[size];
  }

  // A method to add a carrier to the array at a given index
  public void addCarrier(int index, Carrier carrier) {
    // Input validation: the index should be within the bounds of the array
    if (index >= 0 && index < carriers.length) {
      carriers[index] = carrier;
    } else {
      System.out.println("Invalid index");
    }
  }

  // A method to search for free carriers and display their details
  public void searchFreeCarriers() {
    System.out.println("Free carriers:");
    for (Carrier carrier : carriers) {
      // Check if the carrier is not null and its status is true (free)
      if (carrier != null && carrier.getStatus()) {
        carrier.display();
      }
    }
  }

  // A method to search for busy carriers and display their details
  public void searchBusyCarriers() {
    System.out.println("Busy carriers:");
    for (Carrier carrier : carriers) {
      // Check if the carrier is not null and its status is false (busy)
      if (carrier != null && !carrier.getStatus()) {
        carrier.display();
      }
    }
  }
}

// A class to test the application
class Test {
  public static void main(String[] args) {
    // Create a new library with a size of 5
    Library library = new Library(5);

    // Create some carriers and add them to the library
    Carrier c1 = new Book("J.K. Rowling", "Harry Potter and the Philosopher's Stone", 1997, true, 223);
    library.addCarrier(0, c1);

    Carrier c2 = new Book("George Orwell", "1984", 1949, false, 328);HarryPotter
    library.addCarrier(1, c2);

    Carrier c3 = new Carrier("Magazine", "National Geographic", "The Future of Medicine", 2020, true);
    library.addCarrier(2, c3);

    Carrier c4 = new Carrier("CD-ROM", "Microsoft", "Windows XP", 2001, false);
    library.addCarrier(3, c4);

    Carrier c5 = new Carrier("Audio-CD", "Queen", "Bohemian Rhapsody", 1975, true);
    library.addCarrier(4, c5);
 // Search for free carriers and display their details
    library.searchFreeCarriers();

    // Search for busy carriers and display their details
    library.searchBusyCarriers();
  }
}