Question

Create a class class called library which will contain the list of books user should be able to add,delete view list of books in a particular library.

Override hashcode and equal methods, and use hashset to store the data

library class: libcode,libname

book class: bookcode,bookname and price

Please answer with the directions above in java. Thanks

Answer 1

Code For Above Problem:

Book Class Code:

public class Book {
        // Attributes of Book
        private String bookcode;
        private String bookname;
        private double price;

        // Constructor to create Book Object
        public Book(String bookcode, String bookname, double price) {
                this.bookcode = bookcode;
                this.bookname = bookname;
                this.price = price;
        }

        // accessor methods
        public String getBookcode() {
                return bookcode;
        }

        public String getBookname() {
                return bookname;
        }

        public double getPrice() {
                return price;
        }

        // Mutator methods
        public void setBookcode(String bookcode) {
                this.bookcode = bookcode;
        }

        public void setBookname(String bookname) {
                this.bookname = bookname;
        }

        public void setPrice(double price) {
                this.price = price;
        }

        // Overrided hashCode method
        public int hashCode() {
                final int prime = 31;
                int result = 1;
                result = prime * result + ((bookcode == null) ? 0 : bookcode.hashCode());
                result = prime * result + ((bookname == null) ? 0 : bookname.hashCode());
                long temp;
                temp = Double.doubleToLongBits(price);
                result = prime * result + (int) (temp ^ (temp >>> 32));
                return result;
        }

        // Overrided equals method
        public boolean equals(Object obj) {
                // if both references are same
                if (this == obj)
                        return true;
                // if provided obj is null
                if (obj == null)
                        return false;
                // if class name is different
                if (getClass() != obj.getClass())
                        return false;
                // type cast obj to Book
                Book other = (Book) obj;

                // if this object bookcode is null and other bookcode is not null
                if (bookcode == null) {
                        if (other.bookcode != null)
                                return false;
                }
                // if this object bookcode is not equals to other book bookcode
                else if (!bookcode.equals(other.bookcode))
                        return false;
                // if this object bookname is null and other bookname is not null
                if (bookname == null) {
                        if (other.bookname != null)
                                return false;
                }
                // if this object bookname is not equals to other book bookname
                else if (!bookname.equals(other.bookname))
                        return false;
                // if prices are not same
                if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price))
                        return false;
                // if above all conditions are not satisfied both objects are same return true
                return true;
        }

        // toString method to return String representation of Book Object
        public String toString() {
                return "Book [bookcode=" + bookcode + ", bookname=" + bookname + ", price=" + price + "]";
        }
}

Library Class Code:

import java.util.HashSet;

public class Library {
        // attributes of Library
        String libcode;
        String libname;
        HashSet<Book> books;

        // Constructor to create Library Object
        public Library(String libcode, String libname) {
                this.libcode = libcode;
                this.libname = libname;
                this.books = new HashSet<Book>();
        }

        /*
         * Method to add book to book list return true if successfully added and return
         * false if already present
         */
        public boolean add(Book b) {
                return books.add(b);
        }

        /*
         * Method to delete book from book list return true if successfully delete book
         * from list and return false it book not present in list
         */
        public boolean delete(Book b) {
                return books.remove(b);
        }

        // Method to show the books in list
        public void showList() {
                if (books.size() == 0) {
                        System.out.println("No Books in list");
                } else {
                        System.out.println("Books List: ");
                        for (Book b : books) {
                                System.out.println(b);
                        }
                }
        }
}

Images Of Code:

Book Class Code Images:

4 13 } } } 3 public class Book { // Attributes of Book 5 private String bookcode; 6 private String bookname; 7 private double price; 8 9 // Constructor to create Book Object 100 public Book(String bookcode, String bookname, double price) { 11 this.bookcode = bookcode; 12 this.bookname = bookname; this.price = price; 14 15 16 // accessor methods 170 public String getBookcode() { 18 return bookcode; 19 20 210 public String getBookname() { 22 return bookname; 23 24 250 public double getPrice() { 26 return price; 27 28 29 // Mutator methods 300 public void setBookcode(String bookcode) { 31 this.bookcode = bookcode; 32 33 340 public void setBookname (String bookname) { 35 this.bookname = bookname; 36 37 380 public void setPrice (double price) { 39 this.price = price; 40 41 42 // Overrided hashCode method 430 public int hashCode() { 44 final int prime - 31; 45 int result = 1; 46 result = prime * result + ((bookcode == null) ? 0 : bookcode.hashCode()); 47 result = prime * result + ((bookname == null) ? 0 : bookname hashCode()); 48 long temp; به } } }

48 49 50 51 52 53 Long tempi temp = Double doubleToLongBits(price); result = prime * result + (int) (temp (temp >>> 32)); return result; } 154 550 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 920 93 94 95} 96 // Overrided equals method public boolean equals(Object obj) { // if both references are same if (this == obj) return true; // if provided obj is null if (obj == null) return false; // if class name is different if (getClass() != obj.getClass()) return false; // type cast obj to Book Book other = (Book) obj; // if this object bookcode is null and other bookcode is not null if (bookcode == null) { if (other.bookcode != null) return false; 7/ if this object bookcode is not equals to other book bookcode else if (!bookcode.equals(other.bookcode)) return false; // if this object bookname is null and other bookname is not null if (bookname == null) { if (other.bookname != null) return false; 1/ if this object bookname is not equals to other book bookname else if (!bookname.equals(other. bookname)) return false; // if prices are not same if (Double doubleToLongBits(price) != Double.doubleToLongBits(other.price)) return false; // if above all conditions are not satisfied both objects are same return true return true; } ܢܟ // toString method to return String representation of Book Object public String toString() { return "Book [bookcode=" + bookcode + ", bookname=" + bookname + ", price=" + price + "]"; }

Library Class Code Image:

2 6 7 9 11 } ܢܟ 3 import java.util.HashSet; 4 5 public class Library { // attributes of Library String libcode; 8 String Libname; HashSet<Book> books; 10 // Constructor to create Library Object 120 public Library(String libcode, String Libname) { 13 this. libcode = libcode; 14 this. Libname = libname; 15 this.books = new HashSet<Book>(); 16 17 180 19 * Method to add book to book list return true if successfully added and return 20 * false if already present 21 */ 220 public boolean add (Book b) { 23 return books.add(b); 24 25 260 27 * Method to delete book from book list return true if successfully delete book 28 * from list and return false it book not present in list 29 */ 300 public boolean delete (Book b) { 31 return books.remove(b); 32 33 34 // Method to show the books in list 350 public void showList() { 36 if (books.size() == 0) { 37 System.out.println("No Books in list"); 38 } else { 39 System.out.println("Books List: "); 40 for (Book b : books) { 41 System.out.println(b); 42 43 44 45} 46 ܢܟ } }