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i am writing a java method which needs to take note of a set of numbers
generated by the routine as it runs. the problem is that i dont know
beforhand how many of these numbers will be generated, so the simple use of
an array cant be used as java seems to insist of the size of the array to be
declared upfront, where as i say i dont have this information prior to
running the method.

there are other java data constructs but i am a bit bemused as to what would
be appropriate here. i am no java expert so what i am looking for is what
used (or still is i dont know) to be called a 'dynamic array' ie. one whose
size may change throughout the running of a program

thanks

"Jeremy Watts" <> wrote in message
news:Zh23h.5818$...
>i am writing a java method which needs to take note of a set of numbers
> generated by the routine as it runs. the problem is that i dont know
> beforhand how many of these numbers will be generated, so the simple use
> of
> an array cant be used as java seems to insist of the size of the array to
> be
> declared upfront, where as i say i dont have this information prior to
> running the method.
>
> there are other java data constructs but i am a bit bemused as to what
> would
> be appropriate here. i am no java expert so what i am looking for is what
> used (or still is i dont know) to be called a 'dynamic array' ie. one
> whose
> size may change throughout the running of a program

java.util.ArrayList

Matt Humphrey http://www.iviz.com/

On 04.11.2006 16:45, Matt Humphrey wrote:
> "Jeremy Watts" <> wrote in message
> news:Zh23h.5818$...
>> i am writing a java method which needs to take note of a set of numbers
>> generated by the routine as it runs. the problem is that i dont know
>> beforhand how many of these numbers will be generated, so the simple use
>> of
>> an array cant be used as java seems to insist of the size of the array to
>> be
>> declared upfront, where as i say i dont have this information prior to
>> running the method.
>>
>> there are other java data constructs but i am a bit bemused as to what
>> would
>> be appropriate here. i am no java expert so what i am looking for is what
>> used (or still is i dont know) to be called a 'dynamic array' ie. one
>> whose
>> size may change throughout the running of a program
>
> java.util.ArrayList

If numbers are ints and they are later used for lookups (rather than
iterating) a BitSet may also serve well here.

Kind regards

robert

in message <Zh23h.5818$>, Jeremy Watts
('') wrote:

> i am writing a java method which needs to take note of a set of numbers
> generated by the routine as it runs. the problem is that i dont know
> beforhand how many of these numbers will be generated, so the simple use
> of an array cant be used as java seems to insist of the size of the array
> to be declared upfront, where as i say i dont have this information prior
> to running the method.
>
> there are other java data constructs but i am a bit bemused as to what
> would be appropriate here. i am no java expert so what i am looking for
> is what
> used (or still is i dont know) to be called a 'dynamic array' ie. one
> whose size may change throughout the running of a program

You're looking for a Vector.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; Conservatives are not necessarily stupid,
;; but most stupid people are conservatives -- J S Mill

In article <Zh23h.5818$>, Jeremy Watts
took the hamburger meat, threw it on the grill, and I said "Oh Wow"...

> i am writing a java method which needs to take note of a set of numbers
> generated by the routine as it runs. the problem is that i dont know
> beforhand how many of these numbers will be generated, so the simple use of
> an array cant be used as java seems to insist of the size of the array to be
> declared upfront, where as i say i dont have this information prior to
> running the method.
>
> there are other java data constructs but i am a bit bemused as to what would
> be appropriate here. i am no java expert so what i am looking for is what
> used (or still is i dont know) to be called a 'dynamic array' ie. one whose
> size may change throughout the running of a program
>
> thanks
>

Use ArrayList instead.

--
trippy
mhm31x9 Smeeter#29 WSD#30
sTaRShInE_mOOnBeAm aT HoTmAil dOt CoM

NP: "All I Really Want" -- Alanis Morissette

"Now, technology's getting better all the time and that's fine,
but most of the time all you need is a stick of gum, a pocketknife,
and a smile."

-- Robert Redford "Spy Game"

Jeremy Watts wrote:
> i am writing a java method which needs to take note of a set of numbers
> generated by the routine as it runs. the problem is that i dont know
> beforhand how many of these numbers will be generated, so the simple use of
> an array cant be used as java seems to insist of the size of the array to be
> declared upfront, where as i say i dont have this information prior to
> running the method.
>
> there are other java data constructs but i am a bit bemused as to what would
> be appropriate here. i am no java expert so what i am looking for is what
> used (or still is i dont know) to be called a 'dynamic array' ie. one whose
> size may change throughout the running of a program

The closest to dynamic array is ArrayList, an array based implementation
of the java.util.List interface.

However, in the first sentence you mention a "set of numbers". If the
only reason for associating an order with them is because you were
thinking of putting them in an array, then consider a java.util.Set
implementation instead.

In particular, if you frequently ask "Is n in the result set?" then a
HashSet may be more efficient and appropriate than any List implementation.

If the numbers are reasonably small, BitSet may also be a good choice.

If you have not already done so, take a look at the API documents for
java.util. It has a lot of classes for solving "how do I store this
data?" questions.

Patricia

Simon Brooke wrote:
> in message <Zh23h.5818$>, Jeremy Watts
> ('') wrote:
>
> > i am writing a java method which needs to take note of a set of numbers
> > generated by the routine as it runs. the problem is that i dont know
> > beforhand how many of these numbers will be generated, so the simple use
> > of an array cant be used as java seems to insist of the size of the array
> > to be declared upfront, where as i say i dont have this information prior
> > to running the method.
> >
> > there are other java data constructs but i am a bit bemused as to what
> > would be appropriate here. i am no java expert so what i am looking for
> > is what
> > used (or still is i dont know) to be called a 'dynamic array' ie. one
> > whose size may change throughout the running of a program
>
> You're looking for a Vector.
I doubt he's looking for a Vector, ArrayList is much more appropriate
in most circumstances.
>
> --
> (Simon Brooke) http://www.jasmine.org.uk/~simon/
>
> ;; Conservatives are not necessarily stupid,
> ;; but most stupid people are conservatives -- J S Mill

On Sat, 04 Nov 2006 15:07:55 -0800, Daniel Pitts wrote:

> Simon Brooke wrote:
>> You're looking for a Vector.
> I doubt he's looking for a Vector, ArrayList is much more appropriate in
> most circumstances.

Always declare using the List interface, that way you can easily change
the actual implementation to see which gives you the best performance.

HTH,
La`ie Techie