Splitting Vector into smalller sub-Vectors

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Allan Bruce - 26 May 2005 10:32 GMT

Is it possible to efficiently split a large Vector into smaller sub-Vectors
without iterating through it and adding the Objects to the sub-Vectors? If
not, is there a collection which allows this? I dont need random access, I
am just adding blindly to a single collection, then want to split it up at
the end.

Thanks.
Allan

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Boudewijn Dijkstra - 26 May 2005 11:01 GMT

> Is it possible to efficiently split a large Vector into smaller sub-Vectors
> without iterating through it and adding the Objects to the sub-Vectors? If
> not, is there a collection which allows this? I dont need random access, I
> am just adding blindly to a single collection, then want to split it up at
> the end.

java.util.List#subList(int,int)

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Allan Bruce - 27 May 2005 13:07 GMT

>>Is it possible to efficiently split a large Vector into smaller sub-Vectors
>>without iterating through it and adding the Objects to the sub-Vectors? If
[quoted text clipped - 3 lines]
>
> java.util.List#subList(int,int)

I tried using ArrayList for this but I get a ClassCastException error at
the following line:

lArray[j] = (ArrayList)lStates.subList(lStart, lEnd);

What can I do to avoid this? I read the docs but cant see anything that
says what to do.

Thanks.
Allan

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Virgil Green - 27 May 2005 23:35 GMT

>>> Is it possible to efficiently split a large Vector into smaller
>>> sub-Vectors without iterating through it and adding the Objects to
[quoted text clipped - 14 lines]
> Thanks.
> Allan

sublist doesn't split the list. It only provides a view of part of the
underlying list. It does not create a new object. You can't cast it the way
you want because the object that is returned is a RandomAccessSubList, not
an ArrayList.

If you want separate ArrayLists to be created, use

lArray[j] = new ArrayList(lStates.subList(lStart, lEnd));

Which takes the List (or RandamAccessSubList) object from sublist and uses
it to create a new ArrayList.

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Virgil

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Splitting Vector into smalller sub-Vectors

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