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vector

Ram Murthy
Ranch Hand

Joined: Aug 02, 2005
Posts: 91
What is the effect of adding the sixth element to a vector created in the following manner:

new Vector(5, 10);
1. An IndexOutOfBounds exception is raised.
2. The vector grows in size to a capacity of 10 elements
3. The vector grows in size to a capacity of 15 elements
4. Nothing, the vector will have grown when the fifth element was added
Select the most appropriate answer.

Can this question be answered by what is there in Kathy Sierra book ??
Can we expect such questions on collections in the real exam ??

Please advise...

Thanks,
JP


Cheers,
Ram
Henry Wong
author
Sheriff

Joined: Sep 28, 2004
Posts: 18978
    
  40

According to the Java Docs, it will throw an exception, if you try to insert into an index that is greater than the number of elements.

Henry



Books: Java Threads, 3rd Edition, Jini in a Nutshell, and Java Gems (contributor)
Ram Murthy
Ranch Hand

Joined: Aug 02, 2005
Posts: 91
Thanks but that is not my question....
Let me repeat my question is ...

1. Can this question be answered by what is there in Kathy Sierra book ??
2. Can we expect such questions on collections in the real exam ??

Please advise...

Thanks,
JP
Edwin Keeton
Ranch Hand

Joined: Jul 10, 2002
Posts: 214

Whether adding the sixth element throws an exception depends on how it is added to the Vector. If you use add(element), it will be appended to the tail with no exception. If you use add(index, element), it will throw an exception.

You can answer this question with what is in K&B plus reading the API for the Java Collection classes (as recommended by K&B).


SCJP, SCWCD
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19760
    
  20

For answering this question you must know the API for Vector. Now I've read the entire K&B book, and found no API's for any Collection. Hence I think it's very doubtful this kind of questions will be in the exam.

PS: the answer is 3: you create a Vector with initial capacity of 5 and increment of 10. When adding the 6th element, you get an overflow and capacity for another 10 elements is added - there is now capacity for 15 elements.


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Joseph Clark
Ranch Hand

Joined: Sep 10, 2005
Posts: 48
Right, but if you add an element at the sixth place, vector_name[5], straightaway, without filling the vector, you get ArrayOutOfBounds exception. I don't think you will see this question on the exam because it is an ambiguous question.
 
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