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Collection doubt

 
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specified features
*Each element must be unique.
*Contains no duplicate elements.
*Elements are not key/value pairs.
*Accessing an element can be almost as fast as performing a similar operation on an array.


Which of these classes provides the specified features?
a. LinkedList
b. TreeMap
c. TreeSet
d. HashMap
e. HashSet
f. LinkedHashMap
g. Hashtable
h. None of the above

Answer:e.

Doubt: why can't C be the answer as it fulfills the features required

pls help,
gitesh
 
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Since speed is a criteria, it has to be HashSet over TreeSet. The TreeSet stores the items in its natural order, which cannot be changed and which also makes the access slower.
 
Greenhorn
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Hi Gitesh,
The following three are common to TreeSet and HashSet

*Each element must be unique.
*Contains no duplicate elements.
*Elements are not key/value pairs.

Now the last feature is where these differ :

Accessing an element can be almost as fast as performing a similar operation on an array.

This feature makes the choice to be HashSet .

If you are wondering why ..then to give you a hint ...

The HashSet is very fast for searching because of the the hashing .Well this is true for any Hash<table , Map , Set > .
The elements in the TreeSet are kept in a sorted fashion.
 
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"Aalok rulez", please check your private messages. You can see them by clicking My Profile.
 
Greenhorn
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Its Tree set

Cheers!
Rajeev
 
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Originally posted by Rajeev Mishra:
Its Tree set

Cheers!
Rajeev



What's that..
I mean how can you say this...

The answer would be certainly HashSet
 
Jesper de Jong
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Aalok, please check your private messages again.
 
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Hi,
It is HashSet only.

Why because if the requirement is
elements must be in sorted order then the answer is TreeSet

But in above question he did not mention the specific order.

so it must be HashMap
 
Gitesh Ramchandani
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thanks al for help.
I now understand why it should be HashSet and not TreeSet
 
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