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Java Java Data Structures Efficiency! Implement Chooser UI

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());?

1 Answer

Dan Johnson
Dan Johnson
40,532 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.