public BookCollection getByTitle(String title)
{
if (title == "")
{
throw new ArgumentException();
}
BookCollection booksByName = new BookCollection();
foreach (Book book in _items)
{
if (book.title == title)
{
booksByName.Add(book);
}
}
return(booksByName);
}
public BookCollection getByPeriod(DateTime start, DateTime end)
{
if (start > end)
{
throw new ArgumentException();
}
BookCollection booksByPeriod = new BookCollection();
foreach (Book book in _items)
{
DateTime publishDate = book.publishDate;
if (start < publishDate && publishDate < end)
{
booksByPeriod.Add(book);
}
}
return(booksByPeriod);
}
public BookCollection getByTag(String chosenTag)
{
if (chosenTag == "")
{
throw new ArgumentException();
}
BookCollection booksByTag = new BookCollection();
foreach (Book book in _items)
{
String[] tags = book.tags;
foreach (String tag in tags)
{
if (tag == chosenTag)
{
booksByTag.Add(book);
}
}
}
return(booksByTag);
}