Library

public class main {

    public static void main(String[] args) {
        Lib lib = new Lib();


        lib.newBook("Into the Wild","Jon Krakauer","Villard","1996", "9789544745349");
        lib.newBook("My Biography","Roberto Vasilev","My Publishment","2019", "0-1111-1111-1");
        lib.newBook("Harry Potter and the Philosopher Stone","J.K. Rowling","Bloomsbury","1997", "0-7475-3269-9");
        lib.newBook("Darkmouth","Shane Hegarty","Ciela","2015", "978-954-28-1898-4");


        lib.getAllBook();
        System.out.println();
        lib.getBookByAuthor("J.K. Rowling");
        lib.deleteBookByAuthor("J.K. Rowling");
        System.out.println();
        lib.getAllBook();


    }

}
------------
import java.util.*;

public class Lib {
    Map<authors, book> libraryBooks = new HashMap<>();

    public void newBook(String header, String author, String publisher, String dateOfPublishment, String ISBN) {
        libraryBooks.put(new authors(author), new book(header, author, publisher, dateOfPublishment, ISBN));
    }

    public void getBookByAuthor(String author) {
        for (authors authors : libraryBooks.keySet()) {
            if (authors.getAuthor().equals(author)) {
                System.out.println(libraryBooks.get(authors));
            }
        }
    }

    public void deleteBookByAuthor(String author) {

        for(Iterator<Map.Entry<authors, book>> it = libraryBooks.entrySet().iterator(); it.hasNext(); ) {
            Map.Entry<authors, book> entry = it.next();
            if(entry.getKey().getAuthor().equals(author)) {
                it.remove();
            }
        }


    }



    public void deleteBookByName(String name) {
        for(Iterator<Map.Entry<authors, book>> it = libraryBooks.entrySet().iterator(); it.hasNext(); ) {
            Map.Entry<authors, book> entry = it.next();
            if(entry.getValue().getHeader().equals(name)) {
                it.remove();
            }
        }
    }

    public void getAllBook() {
        for (authors authors : libraryBooks.keySet()) {
            System.out.println(libraryBooks.get(authors));

        }

    }

    public void getBookByName(String name) {
        for (book book : libraryBooks.values()) {
            if (book.getHeader().equals(name)) {
                for (authors authors : libraryBooks.keySet()) {
                    if (authors.getAuthor().equals(book.getAuthor())) {
                        System.out.println(libraryBooks.get(authors));
                    }
                }

            }
        }
    }



}
------------

public class book extends Lib {
      protected String header;
        protected String author;
        protected String publisher;
        protected String dateOfPublishment;
        protected String ISBN;

        public book(String header, String author, String publisher, String dateOfPublishment, String ISBN) {
            this.header = header;
            this.author = author;
            this.publisher = publisher;
            this.dateOfPublishment = dateOfPublishment;
            this.ISBN = ISBN;
        }

        public String getHeader() {
            return header;
        }

        public String getAuthor() {
            return author;
        }

        public String getPublisher() {
            return publisher;
        }

        public String getDateOfPublishment() {
            return dateOfPublishment;
        }

        public String getISBN() {
            return ISBN;
        }
        @Override
        public String toString() {
            return String.format("Book: '%s' Author: '%s' Publisher: '%s' Published: '%s' Date of publishment: '%s'",this.getHeader(),this.getAuthor(),this.getPublisher(),this.getDateOfPublishment(),this.getISBN());
        }
    }
-------------

public class authors {
      private String author;

        public String getAuthor() {
            return author;
        }

        public authors(String author) {
            this.author = author;
        }
}