Re: what am i doing wrong here?


"Wibble" <Wibble@xxxxxxxxxxxxxx> wrote in message
news:XaKdnXKDMdRhTTzfRVn-uQ@xxxxxxxxxx
> Jeremy Watts wrote:
>> "Andrew McDonagh" <news@xxxxxxxxxxxxxxxxxxxxx> wrote in message
>> news:d7rte8$cda$1@xxxxxxxxxxxxxxxxxxxxxxxx
>>
>>>Jeremy Watts wrote:
>>>
>>>>Hi,
>>>>
>>>>I've written a Java method that uses a list to return 5
>>>>three-dimensional arrays containing 'Big Decimal' entries. However I
>>>>also want to return a single boolean type variable, but cant seem to get
>>>>the program to do this.
>>>>
>>>>My method basically goes :-
>>>>
>>>>start method {
>>>>
>>>>declare arrays and variables
>>>>List result = new ArrayList(5)
>>>>..
>>>>..
>>>>..
>>>>..
>>>>REST OF METHOD
>>>>..
>>>>..
>>>>..
>>>>result.add(first array)
>>>>result.add(second array)
>>>>etc
>>>>result.add(fifth array)
>>>>
>>>>return (result)
>>>>
>>>>end method }
>>>>
>>>>
>>>>This works fine for just the arrays, but if I attempt to add the line
>>>>'result.add(LDMexists)' , to return the boolean variable 'LDMexists'
>>>>then I get the error message ' cannot resolve symbol - method
>>>>add(boolean)'
>>>>
>>>>I have declared the boolean type LDMexists, so I cant see what I'm doing
>>>>wrong here - how do I get it to return the five arrays and the boolean
>>>>variable LDMexists?
>>>>
>>>>Thanks
>>>
>>>the ArrayList only allows Object references to be added, where as
>>>'boolean' (Note the lowercase B) is a primitive not an object.
>>>
>>>you can change the code to...
>>>
>>>result.add(Boolean.valueOf(LDMexists));
>>>
>>>This adds a reference to the Boolean object (note the uppercase B) to the
>>>arraylist.
>>>
>>>http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Boolean.html#valueOf(boolean)
>>>
>>>HTH
>>>
>>>Andrew
>>
>>
>> Hi Andrew,
>>
>> Thanks for that, that seems to work. How would you then reference that
>> variable though once the procedure has been called? I cant seem to get
>> that bit to work now.
>>
>> Thanks
>> Jeremy
> I think that you're probably abusing ArrayList as a typeless container.
> Among other things, it forces you to typecast values when you access them,
> know the positional types or infer them, and package a primitive as an
> object Boolean.
>
> A better approach would be to create class to contain the
> returned object and use appropriate names and types for each member. It
> will actually run faster too since ArrayList has to do a bunch of stuff
> to support it being a growable, general purpose container.

how do you do that though?? sorry i'm a newbie still. the list thing that
andrew mentioned has worked, its just i now dont know how to access the
boolean variable once i've returned it.


.

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