public List<Book> booksForTag(Tag tag) {
final boolean isNull = Tag.NULL.equals(tag);
final LinkedList<Book> filtered = new LinkedList<Book>();
for (Book b : books()) {
final List<Tag> bookTags = b.tags();
if (isNull && bookTags.isEmpty() || bookTags.contains(tag)) {
filtered.add(b);
}
}
return filtered;
}
public List<String> titlesForTag(Tag tag, int limit) {
if (limit <= 0) {
return Collections.emptyList();
}
final ArrayList<String> titles = new ArrayList<String>(limit);
final boolean isNull = Tag.NULL.equals(tag);
synchronized (myBooksByFile) {
for (Book b : myBooksByFile.values()) {
if (isNull ? b.tags().isEmpty() : b.tags().contains(tag)) {
titles.add(b.getTitle());
if (--limit == 0) {
break;
}
}
}
}
return titles;
}