Library

package pl.kimes.core;

public class Main {

    public static void main(String[] args) {
        Library library = new Library();

        Book b = new Book("Java For Begginers", "2017", "Jakub Niedzielski");
        Book b2 = new Book("Java For Begginers", "2017", "Jakub Niedzielski");
        Book b3 = new Book("Java for dummies", "2010", "Unknown");

        library.addBook(b);
        library.addBook(b2);
        library.addBook(b3);
        library.removeBook(1);

        library.getAllBooks();

    }

}
package pl.kimes.core;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Library {

    private int uniqueID;
    private Map<Integer, Book> bookMap = new HashMap<>();
    private Map<Book, Integer> copiesMap = new HashMap<>();
    private Map<Book, List<String>> borrowersMap = new HashMap<>();

    public void addBook(Book newAddbook) {
        Integer id = ++uniqueID;
        for (Book book : bookMap.values()) {
            if (book.equals(newAddbook)) {
                int numberOfCopies = getNumberOfCopies(newAddbook);
                newAddbook.setId(id);
                numberOfCopies++;
                bookMap.put(id, newAddbook);
                copiesMap.put(newAddbook, numberOfCopies);
                return;
            }
        }
        int numberOfCopies = 1;
        newAddbook.setId(id);
        bookMap.put(id, newAddbook);
        copiesMap.put(newAddbook, numberOfCopies);
    }

    public void lendBook(Integer bookID, String borrowersName) {
        Book bookValues = bookMap.get(bookID);
        int numberOfCopies = copiesMap.get(bookValues);
        if (numberOfCopies == 0) {
            System.out.println("Can't lend this book, it's been alredy lent by "
                    + borrowersMap.get(bookValues).toString().replace("[", "").replace("]", ""));
        } else {
            List<String> borrowersList = borrowersMap.get(bookValues);
            if (borrowersList == null) {
                borrowersList = new ArrayList<>();
                borrowersMap.put(bookValues, borrowersList);
            }
            borrowersList.add(borrowersName);

            copiesMap.put(bookValues, copiesMap.get(bookValues) - 1);

        }
    }

    public void returnBook(Integer bookID, String returnersName) {
        Book bookValues = bookMap.get(bookID);
        List<String> borrowersList = borrowersMap.get(bookValues);
        if (borrowersList == null) {
            System.out.println("This book wasn't lent by you, you can't return it");
            return;
        }
        if (!borrowersList.contains(returnersName)) {
            System.out.println("Invalid name");
        }

        borrowersList.remove(returnersName);
        copiesMap.put(bookValues, copiesMap.get(bookValues) + 1);
    }

    public void removeBook(Integer bookID) {
        Book bookValues = bookMap.get(bookID);
        if (bookValues != null) {
            if (borrowersMap.get(bookValues) == null) {
                bookMap.remove(bookID);
                copiesMap.put(bookValues, copiesMap.get(bookValues) - 1);
            } else {
                System.out.println("Can't remove that book right now, it's lent");
            }
        } else {
            System.out.println("Invalid ID number");

        }
    }

    public void getInfoByID(Integer bookID) {
        Book book = bookMap.get(bookID);
        if (book != null) {
            book.print();
            printCopies(book);
        }
    }

    public void getAllBooks() {
        for (Book book : bookMap.values()) {
            book.print();
            printCopies(book);
        }
    }

    public void getAllByTitle(String title) {
        for (Book book : bookMap.values()) {
            if (title.equals(book.getTitle())) {
                book.print();
                printCopies(book);
            }
        }

    }

    public void getAllByAuthor(String author) {
        for (Book book : bookMap.values()) {
            if (author.equals(book.getAuthor())) {
                book.print();
                printCopies(book);
            }
        }
    }

    public void getAllByYear(String year) {
        for (Book book : bookMap.values()) {
            if (year.equals(book.getYear())) {
                book.print();
                printCopies(book);
            }
        }
    }

    public void getAllByAuthorAndYear(String author, String year) {
        for (Book book : bookMap.values()) {
            if (author.equals(book.getAuthor()) && (year.equals(book.getYear()))) {
                book.print();
                printCopies(book);
            }
        }
    }

    private void printCopies(Book book) {
        copiesMap.get(book);
        System.out.println("Number of copies: " + getNumberOfCopies(book));

    }

    private int getNumberOfCopies(Book book) {
        return copiesMap.get(book);

    }

}
package pl.kimes.core;

public class Book {

    private int id;
    private String title;
    private String year;
    private String author;

    public Book(String title, String year, String author) {
        this.title = title;
        this.year = year;
        this.author = author;
    }

    public String getTitle() {
        return title;
    }

    public String getYear() {
        return year;
    }

    public String getAuthor() {
        return author;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void print() {
        System.out.println("-----");
        System.out.println("ID number: " + this.getId());
        System.out.println("Title: " + this.getTitle());
        System.out.println("Year: " + this.getYear());
        System.out.println("Author: " + this.getAuthor());
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((author == null) ? 0 : author.hashCode());
        result = prime * result + ((title == null) ? 0 : title.hashCode());
        result = prime * result + ((year == null) ? 0 : year.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (author == null) {
            if (other.author != null)
                return false;
        } else if (!author.equals(other.author))
            return false;
        if (title == null) {
            if (other.title != null)
                return false;
        } else if (!title.equals(other.title))
            return false;
        if (year == null) {
            if (other.year != null)
                return false;
        } else if (!year.equals(other.year))
            return false;
        return true;
    }


    // old implementation of equals method

    // @Override
    // public boolean equals(Object arg0) {
    // if (Book.class.isInstance(arg0)) {
    //
    // return this.author.equals(((Book) arg0).author) &&
    // this.year.equals(((Book) arg0).year) &&
    // this.title.equals(((Book) arg0).title);
    // }
    // return false;
    // }

}