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sets

nitin sharma
Ranch Hand

Joined: Feb 24, 2001
Posts: 290
Which option does not allow the duplicates to be stored.
1)java awt.util.Set
2)java.util.List
3)java.util.SortedSet
4) java.util.Map
I think (1),(3),(4) are correct.Please correct me if im wrong.
Tracy Qi
Ranch Hand

Joined: Apr 23, 2001
Posts: 37
I think the only choice is 1. Set. It won't allow duplicates. Couldn't find java.util.SortedSet anywhere.
basically there are two types of collections:
Collection: SET - No duplicates
List - Ordered
Map: a et of mappings or associations between objects.

Hope this help.
Manfred Leonhardt
Ranch Hand

Joined: Jan 09, 2001
Posts: 1492
Hi Nitin,
The question is worded very badly! If you typed in the choices correctly then the answers would be: 3 (for sure) and 4 (maybe)
Reasons:
1. No such class, interface, or package exists
2. List interface allows duplicates
3. SortedSet extends java.util.Set interface and does not allow duplicates
4. If we take the key-value pair as a stored value then the java.util.Map doesn't allow duplicates. If we are only talking about value then Map does allow duplicates.

Regards,
Manfred.
Ravindra Mohan
Ranch Hand

Joined: Mar 16, 2001
Posts: 216
Hi Nitin,
I agree with Manfred, your question is a bit wrongly worded, but the answer is as follows:
Basically <code> Collection </code> is an interface
under <code> java.util package </code> This interface is extended by other interfaces viz., <code> BeanContext, BeanContextServices, Set , SortedSet , List </code>. Of the five listed above only <code> Set and SortedSet </code> do not allow duplicates element to be added to the container. On the other hand <code> SortedMap </code> though not a part of <code>Collection </code> interface is part of Collection framework and it impliments the <code> Map </code> interface, and it does not allow duplicate values to be added to
the container having them (as pointed by Mansfeld in his code). So the correct answer would be (1) , (3) and (4).
Hope this suffices your querry.
Rgds,
Ravindra Mohan.

[This message has been edited by Ravindra Mohan (edited May 03, 2001).]
 
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