【笔记】Eclipse and Java for Total Beginners—014

Lesson 14 – Finish checkOut Method

• Write getBooksForPerson method
• Introduce for each loop
• Introduce logical ‘and’ operator &&
• NullPointerException errors
• Complete checkOut Method

package org.totalbeginner.tutorial;

 import java.util.ArrayList;

 import org.totoalbeginner.tutorial.Person;

 public class MyLibrary {

    String name;
    public String getName() {
        return name;
    }

    public ArrayList<Person> getPeople() {
        return people;
    }

    public ArrayList<Book> getBooks() {
        return books;
    }

    ArrayList<Person> people;
    ArrayList<Book> books;

    public MyLibrary(String name) {
        this.name = name;
        books = new ArrayList<Book>();
        people = new ArrayList<Person>();
        
    }

    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;
    }
}