java - 我只能访问列表中的第一项

Question

public class Catalogue() {
  private List<Book> booksAvailable;
  private List<Book> booksRented:

  public Catalogue() {
    booksAvailable.add(new Book("Matrix", 1999, new Genre("SciFi"), 3));
    booksAvailable.add(new Book("Jurassic Park", 1999, new Genre("SciFi"), 3));
    boosAvailable.add(new Book("Terminator", 1999, new Genre("SciFi"), 3));
    booksRented = new LinkedList<Book> ();
  }

  public void rentBook() {
    System.out.println("Rent a book:");
    System.out.println("Enter the title of a book you want to rent: ");
    String name = In.NextLine();
    for (Book book: booksAvailable) {
      if (book.getName.equals(name)) {
        System.out.println("Renting " + name);
        booksAvailable.remove(book);
        booksRented.add(book);
        break;
      } else {
        System.out.println("No such books found");
      }
    }
  }
}

运行此代码时只能租用 Matrix 书。当我尝试租另一本书(例如《侏罗纪公园》)时，它说找不到书。当我关闭程序并再次运行它并尝试租用第二本书时，它再次显示未找到书籍。请帮我解决这个问题。我在这段代码中遇到什么问题。谢谢

Answer 1

正如其他人指出的那样，在迭代列表时修改列表是危险的。

我建议尝试使用 HashMap，特别是如果 name 是您正在查看的唯一字段。

public class Catalogue {
    private Map<String, Book> booksAvailable;
    private Map<String, Book> booksRented;

    public Catalogue() {
        booksAvailable = new HashMap<>();
        booksAvailable.put("Matrix", new Book("Matrix", 1999, new Genre("SciFi"), 3));
        booksAvailable.put("Jurassic Park", new Book("Jurassic Park", 1999, new Genre("SciFi"), 3));
        booksAvailable.put("Terminator", new Book("Terminator", 1999, new Genre("SciFi"), 3));
        booksRented = new HashMap<>();
    }

    public void rentBook() {
        System.out.println("Rent a book:");
        System.out.println("Enter the title of a book you want to rent: ");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        if (booksAvailable.containsKey(name)) {
            Book book = booksAvailable.get(name);
            System.out.println("Renting " + name);
            booksAvailable.remove(name);
            booksRented.put(name, book);
        } else {
            System.out.println("No such books found");
        }
    }
}