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Which of these statements about whether Map is part of the Collection hierarchy is correct?

  • A.Map extends Collection.
  • B.Map extends Set.
  • C.Map extends Collection only through its SortedMap subinterface.
  • D.Map is a separate interface and does not extend Collection.

Answer: D

A collection holds elements while a map holds key-value pairs, so the two hierarchies are separate and Map has no iterator of its own. It offers collection views instead, keySet, values and entrySet, which is how a map is iterated.

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