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feat: adds Lesson 10 homework assignment and stretch requirement. (#284)
* feat: adds library implementation and tests * chore: updated doco comment. * docs: adds additional assignment details * chore: updates section title.
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‎lesson_10/README.md

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* Read HFDP 1-2.
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* Complete [Applying SOLID principles](#applying-solid-principles) exercise.
2020

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## Applying SOLID Principles
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## Applying SOLID Principles (Library Management System, Part II)
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* TODO(anthonydmays): Add details
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In this assignment, you will be given starting implementations for the `Library`, `Book`, and `Patron` classes. You will need to add the following enhancements to support new functionality:
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* We now want to support the concept of a `Librarian`. A librarian should be able to check out or check in books just like other patrons. Books can no longer be added or removed from the `Library` without a librarian.
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* We also want to support other types of media formats, including `Dvd`, `Magazine`, and `Newspaper` types. Patrons cannot check out `Magazine` or `Newspaper` items.
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* [Stretch] Add the ability to search for items in the library by title, ISBN, author, or type. Extra credit will not be assigned unless the previous requirements have been met.
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You will need to make changes to code in the [solid/][solid-folder] sub-folder and submit your PR for credit. Don't forget to follow the Conventional Commit spec for your commit messages and pull requests title and descriptions.
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[solid-folder]: ./solid/

‎lesson_10/solid/solid_app/src/main/java/com/codedifferently/lesson10/library/Book.java

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package com.codedifferently.lesson10.library;
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import com.codedifferently.lesson10.library.exceptions.LibraryNotSetException;
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import com.codedifferently.lesson10.library.exceptions.WrongLibraryException;
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import java.util.List;
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import java.util.Objects;
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/** Represents a book. */
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public class Book {
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private Library library;
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private String title;
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private String isbn;
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private List<String> authors;
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private int numberOfPages;
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/**
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* Create a new book with the given title, ISBN, authors, and number of pages.
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*
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* @param title The title of the book.
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* @param isbn The ISBN of the book.
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* @param authors The authors of the book.
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* @param numberOfPages The number of pages in the book.
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*/
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public Book(String title, String isbn, List<String> authors, int numberOfPages) {
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this.title = title;
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this.isbn = isbn;
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this.authors = authors;
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this.numberOfPages = numberOfPages;
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}
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/**
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* Get the id of the book.
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*
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* @return The id of the book.
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*/
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public String getId() {
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return this.isbn;
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}
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/**
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* Get the library that the book is in.
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*
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* @param library The library that the book is in.
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* @throws WrongLibraryException If the book is not in the library.
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*/
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public void setLibrary(Library library) throws WrongLibraryException {
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if (library != null && !library.hasBook(this)) {
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throw new WrongLibraryException(
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"Book " + this.getId() + " is not in library " + library.getId());
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}
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this.library = library;
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}
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/** Get the title of the book. */
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public String getTitle() {
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return title;
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}
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/** Get the ISBN of the book. */
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public String getIsbn() {
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return isbn;
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}
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/** Get the authors of the book. */
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public List<String> getAuthors() {
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return authors;
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}
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/** Get the number of pages in the book. */
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public int getNumberOfPages() {
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return numberOfPages;
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}
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/**
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* Check if the book is checked out.
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*
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* @return True if the book is checked out, false otherwise.
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* @throws LibraryNotSetException If the library is not set for the book.
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*/
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public boolean isCheckedOut() throws LibraryNotSetException {
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if (this.library == null) {
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throw new LibraryNotSetException("Library not set for book " + this.getId());
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}
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return library.isCheckedOut(this);
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}
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@Override
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public boolean equals(Object o) {
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if (this == o) return true;
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if (!(o instanceof Book)) return false;
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Book book = (Book) o;
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return Objects.equals(getIsbn(), book.getIsbn());
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}
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@Override
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public int hashCode() {
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return Objects.hash(getId());
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}
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@Override
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public String toString() {
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return "Book{" + "id='" + getId() + '\'' + ", title='" + getTitle() + '\'' + '}';
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}
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}

‎lesson_10/solid/solid_app/src/main/java/com/codedifferently/lesson10/library/Library.java

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package com.codedifferently.lesson10.library;
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import com.codedifferently.lesson10.library.exceptions.BookCheckedOutException;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Set;
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/** Represents a library. */
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public class Library {
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private Set<String> bookIds = new HashSet<>();
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private Set<String> checkedOutIsbns = new HashSet<>();
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private Map<String, Set<Book>> checkedOutBooksByPatron = new HashMap<>();
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private Set<String> patronIds = new HashSet<>();
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private String id;
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/**
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* Create a new library with the given id.
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*
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* @param id The id of the library.
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*/
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public Library(String id) {
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this.id = id;
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}
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/**
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* Get the id of the library.
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*
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* @return The id of the library.
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*/
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public String getId() {
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return this.id;
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}
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/**
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* Add a book to the library.
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*
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* @param book The book to add.
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*/
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public void addBook(Book book) {
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this.bookIds.add(book.getId());
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book.setLibrary(this);
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}
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/**
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* Remove a book from the library.
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*
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* @param book The book to remove.
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*/
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public void removeBook(Book book) throws BookCheckedOutException {
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if (this.isCheckedOut(book)) {
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throw new BookCheckedOutException("Cannot remove checked out book.");
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}
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this.bookIds.remove(book.getId());
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book.setLibrary(null);
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}
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/**
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* Add a patron to the library.
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*
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* @param patron The patron to add.
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*/
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public void addPatron(Patron patron) {
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this.patronIds.add(patron.getId());
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this.checkedOutBooksByPatron.put(patron.getId(), new HashSet<>());
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patron.setLibrary(this);
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}
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/**
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* Remove a patron from the library.
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*
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* @param patron The patron to remove.
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*/
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public void removePatron(Patron patron) throws BookCheckedOutException {
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if (this.checkedOutBooksByPatron.get(patron.getId()).size() > 0) {
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throw new BookCheckedOutException("Cannot remove patron with checked out books.");
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}
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this.patronIds.remove(patron.getId());
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this.checkedOutBooksByPatron.remove(patron.getId());
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patron.setLibrary(null);
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}
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/**
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* Check out a book to a patron.
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*
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* @param book The book to check out.
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* @param patron The patron to check out the book to.
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* @return True if the book was checked out, false otherwise.
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*/
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public boolean checkOutBook(Book book, Patron patron) {
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if (!this.canCheckOutBook(book, patron)) {
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return false;
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}
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this.checkedOutIsbns.add(book.getIsbn());
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this.checkedOutBooksByPatron.get(patron.getId()).add(book);
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return true;
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}
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private boolean canCheckOutBook(Book book, Patron patron) {
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if (!this.hasBook(book)) {
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return false;
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}
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if (this.isCheckedOut(book)) {
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return false;
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}
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if (!this.hasPatron(patron)) {
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return false;
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}
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return true;
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}
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/**
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* Check if the library has the given book.
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*
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* @param book The book to check for.
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* @return True if the library has the book, false otherwise.
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*/
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public boolean hasBook(Book book) {
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return this.bookIds.contains(book.getId());
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}
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/**
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* Check if the given book is checked out.
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*
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* @param book The book to check.
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* @return True if the book is checked out, false otherwise.
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*/
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public boolean isCheckedOut(Book book) {
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return this.checkedOutIsbns.contains(book.getIsbn());
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}
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/**
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* Check if the library has the given patron.
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*
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* @param patron The patron to check for.
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* @return True if the library has the patron, false otherwise.
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*/
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public boolean hasPatron(Patron patron) {
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return this.patronIds.contains(patron.getId());
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}
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/**
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* Return a book to the library.
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*
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* @param book The book to return.
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* @param patron The patron returning the book.
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* @return True if the book was returned, false otherwise.
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*/
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public boolean checkInBook(Book book, Patron patron) {
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if (!this.hasBook(book)) {
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return false;
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}
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this.checkedOutIsbns.remove(book.getIsbn());
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this.checkedOutBooksByPatron.get(patron.getId()).remove(book);
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return true;
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}
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/**
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* Get the books checked out by a patron.
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*
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* @param patron The patron to get the books for.
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* @return The books checked out by the patron.
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*/
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public Set<Book> getCheckedOutByPatron(Patron patron) {
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return this.checkedOutBooksByPatron.get(patron.getId());
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}
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@Override
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public String toString() {
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return "Library{"
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+ "bookIds="
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+ bookIds
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+ ", checkedOutIsbns="
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+ checkedOutIsbns
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+ ", checkedOutBooksByPatron="
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+ checkedOutBooksByPatron
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+ ", patronIds="
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+ patronIds
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+ '}';
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}
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}

‎lesson_10/solid/solid_app/src/main/java/com/codedifferently/lesson10/library/Patron.java

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package com.codedifferently.lesson10.library;
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import com.codedifferently.lesson10.library.exceptions.LibraryNotSetException;
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import com.codedifferently.lesson10.library.exceptions.WrongLibraryException;
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import java.util.Objects;
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import java.util.Set;
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/** Represents a patron of a library. */
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public class Patron {
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private Library library;
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private String name;
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private String email;
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/**
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* Create a new patron with the given name and email.
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*
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* @param name The name of the patron.
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* @param email The email of the patron.
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*/
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public Patron(String name, String email) {
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this.name = name;
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this.email = email;
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}
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/**
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* Get the library that the patron is in.
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*
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* @param library The library that the patron is in.
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* @throws WrongLibraryException If the patron is not in the library.
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*/
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public void setLibrary(Library library) throws WrongLibraryException {
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if (library != null && !library.hasPatron(this)) {
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throw new WrongLibraryException(
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"Patron " + this.getId() + " is not in library " + library.getId());
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}
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this.library = library;
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}
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/** Get the name of the patron. */
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public String getName() {
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return this.name;
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}
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/** Get the email of the patron. */
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public String getId() {
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return this.email;
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}
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/**
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* Gets the books currently checked out to the patron.
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*
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* @return The books currently checked out to the patron.
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* @throws LibraryNotSetException If the library is not set for the patron.
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*/
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public Set<Book> getCheckedOutBooks() throws LibraryNotSetException {
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if (this.library == null) {
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throw new LibraryNotSetException("Library not set for patron " + this.getId());
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}
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return this.library.getCheckedOutByPatron(this);
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}
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@Override
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public boolean equals(Object o) {
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if (this == o) return true;
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if (!(o instanceof Patron)) return false;
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Patron patron = (Patron) o;
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return Objects.equals(getId(), patron.getId());
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}
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@Override
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public int hashCode() {
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return Objects.hash(getId());
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}
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@Override
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public String toString() {
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return "Patron{" + "id='" + getId() + '\'' + ", name='" + getName() + '\'' + '}';
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}
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}

‎lesson_10/solid/solid_app/src/main/java/com/codedifferently/lesson10/library/exceptions/BookCheckedOutException.java

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package com.codedifferently.lesson10.library.exceptions;
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public class BookCheckedOutException extends RuntimeException {
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public BookCheckedOutException(String message) {
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super(message);
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}
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}

‎lesson_10/solid/solid_app/src/main/java/com/codedifferently/lesson10/library/exceptions/LibraryNotSetException.java

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package com.codedifferently.lesson10.library.exceptions;
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public class LibraryNotSetException extends RuntimeException {
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public LibraryNotSetException(String message) {
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super(message);
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}
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}

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