What is the time complexity of the java.util.HashMap 'keySet () method?

Question

I am trying to implement a flat sweep algorithm, and for this I need to know the time complexity of java.util.HashMap class' keySet () . I suspect this is O (n log n). Am I right?

Clarification point: I am talking about the time complexity of the keySet () method; iterating through the returned Set will obviously take O (n) time.

Answer 1

Actually, getting a set of keys is O(1)cheap. This is because HashMap.keyset () returns the actual KeySet associated with the HashMap.

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Answer 2

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Answer 3

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Answer 4

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Answer 5

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Answer 6

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