Machine-translated by Google. Questions are authored in English.
Top

Discussion

Consider which method a TreeSet uses to decide that two elements are the same. Which statement is correct?

  • A.Reference identity, since a sorted set stores each element once.
  • B.compareTo or the supplied Comparator, returning zero, rather than equals.
  • C.equals, exactly as HashSet does.
  • D.hashCode first, then equals to confirm.

Answer: B

Ordering is the sole notion of sameness in a sorted set, so two elements whose comparison returns zero count as duplicates however equals answers. A comparator inconsistent with equals therefore produces a set that behaves oddly against the Set contract, which the javadoc warns about explicitly.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.