Java Programming - Objects and Collections - Discussion


Which statement is true for the class java.util.HashSet?

[A]. The elements in the collection are ordered.
[B]. The collection is guaranteed to be immutable.
[C]. The elements in the collection are guaranteed to be unique.
[D]. The elements in the collection are accessed using a unique key.

Answer: Option C


Option C is correct. HashSet implements the Set interface and the Set interface specifies collection that contains no duplicate elements.

Option A is wrong. HashSet makes no guarantees as to the iteration order of the set; in particular, it does not guarantee that the order will remain constant over time.

Option B is wrong. The set can be modified.

Option D is wrong. This is a Set and not a Map.

Aas said: (Jul 25, 2011)  
Can you show this problem in program?

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