Lesson 16 Null Pointer Error

[NewbieDoo]

package org.totalbeginner.tutorial;

{
import java.util.ArrayList;
public class MyLibrary {
    String name;
    ArrayList<Book> books;
    ArrayList<Person> people;
    public MyLibrary(String name) {
        this.name=name;
        books = new ArrayList<Book>();
        people = new ArrayList<Person>();

    }
    public String getName() {
        return name;
    }
    public ArrayList<Book> getBooks() {
        return books;
    }
    public ArrayList<Person> getPeople() {
        return people;
    }
    public void addBook(Book b1) {
        this.books.add(b1);

    }
    public void removeBook(Book b1) {
        this.books.remove(b1);

    }
    public void addPerson(Person p1) {
        this.people.add(p1);

    }
    public void removePerson(Person p1) {
        this.people.remove(p1);
    }
    public boolean checkOut(Book b1, Person p1) {
        int booksOut = this.getBooksForPerson(p1).size();

        if ((b1.getPerson()==null)&&
                (booksOut < p1.getMaximumBooks())){
            b1.setPerson(p1);
            return true;
        }
        else {
            return false;
        }

    }

    public boolean checkIn(Book b1) {
        if (b1.getPerson() != null) {
            b1.setPerson(null);
            return true;
        }
        else {
            return false;
        }
    }
    public ArrayList<Book> getBooksForPerson(Person p1) {
        ArrayList<Book> result = new ArrayList<Book>();
        for (Book aBook : this.getBooks()){
            if ((aBook.getPerson() != null)&& 
                    (aBook.getPerson().getName()
                    .equals(p1.getName())))

            {
                result.add(aBook);

            }

        }
        return result;

    }
    public ArrayList<Book> getAvailableBooks() {
        ArrayList<Book> result = new ArrayList<Book>();
        for (Book aBook : this.getBooks()){
            if (aBook.getPerson() == null){
                result.add(aBook);

            }

        }
        return result;

    }
    public ArrayList<Book> getUnavailableBooks() {
        ArrayList<Book> result = new ArrayList<Book>();
        for (Book aBook : this.getBooks()){
            if (aBook.getPerson() != null){
                result.add(aBook);

            }

        }
        return result;
    }
    public String toString() {
        return this.getName() + ": " +
        this.getBooks().size()+ " books; " +
        this.getPeople().size() + " people.";

    }

    public static void main(String[] args) {
        // create a new MyLibrary
        //This allows Java program to read parms from a command line
        MyLibrary testLibrary = new MyLibrary("Test Drive Library");
        Book b1 = new Book("War And Peace");
        Book b2 = new Book("Great Expectations");
        b1.setAuthor("Tolstoy");
        b2.setAuthor("Dickens");
        Person jim = new Person();
        Person sue = new Person();
        jim.setName("Jim");
        sue.setName("Sue");

        testLibrary.addBook(b1);
        testLibrary.addBook(b2);
        testLibrary.addPerson(jim);
        testLibrary.addPerson(sue);

        System.out.println("Just Created new library");
        testLibrary.printStatus();

        System.out.println("Check out War And Peace to Sue");
        testLibrary.checkOut(b1, sue);
        testLibrary.printStatus();

        System.out.println("Do some more stuff");
        testLibrary.checkIn(b1);
        testLibrary.checkOut(b2, jim);
        testLibrary.printStatus();

    }
    private void printStatus() {
        System.out.println("Status Report of MyLibrary \n" + this.toString());
    for (Book thisBook : this.getBooks()) {
        System.out.println(thisBook);
    }

    for (Person p : this.getPeople()) {
        int count = this.getBooksForPerson(p).size();
        System.out.println(p + " (has " + count + " of my books)");

    }
    System.out
            .println(" Books Available:  " + this.getAvailableBooks().size());
    System.out.println("---End of Status Report ---");

    }

}
}