Welcome to the Treehouse Community
Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.
Looking to learn something new?
Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.Start your free trial
Is artists a List or a Set? Very confused.
For the statement
List<String> artists = new ArrayList(mSongBook.getArtists());
If we want artists to be a set, why not write:
Set<String> artists = new ArrayList(mSongBook.getArtists());?
Dan Johnson40,532 Points
Sets are unordered, so the method of requesting an index from the user requires the conversion to an
ArrayList (or some other ordered collection) so the get method can be called. artists starts out as a
Set instead of an
ArrayList since it's generated from the call to keySet.
Most classes in the Collections framework have a constructor that accepts anything implementing the
Collection interface so swapping between them isn't too much of a hassle.