ArrayList vs. List

[puzzlecracker]

I noticed in my code, which is essentially an api for the client, that
I return ArrayList object to the client. In my case, list consist of
some objects that user only need to iterate over, hence no
modification to list is done after it filled by me.

What do you think is the best data structure for this requirement?

Thanks

[Ignacio Machin ( .NET/ C# MVP )]

On Oct 16, 11:05 am, puzzlecracker <[e-mail]:

I noticed in my code, which is essentially an api for the client, that
I return ArrayList object to the client. In my case, list consist of
some objects that user only need to iterate over, hence no
modification to list is done after it filled by me.

What do you think is the best data structure for this requirement?

Thanks

You should return a readonly collection. Take a look at
ReadOnlyCollection , it's in System.Collections.ObjectModel

[puzzlecracker]

On Oct 16, 11:27*am, "Ignacio Machin ( .NET/ C# MVP )"
<[e-mail]:

On Oct 16, 11:05 am, puzzlecracker <[e-mail]:

I noticed in my code, which is essentially an api for the client, that
I return ArrayList object to the client. In my case, list consist of
some objects that user only need to iterate over, hence no
modification to list is done after it filled by me.

What do you think is the best data structure for this requirement?

Thanks

You should return a readonly collection. Take a look at
ReadOnlyCollection , it's in System.Collections.ObjectModel

I think it is part of 3.0+, I need to support .NET 2.0... suggestions?

[Mythran]

"puzzlecracker" <ir*********@gmail.comwrote in message
news:38**********************************@k16g2000 hsf.googlegroups.com...

On Oct 16, 11:27 am, "Ignacio Machin ( .NET/ C# MVP )"
<[e-mail]:

>On Oct 16, 11:05 am, puzzlecracker <[e-mail]:

I noticed in my code, which is essentially an api for the client, that
I return ArrayList object to the client. In my case, list consist of
some objects that user only need to iterate over, hence no
modification to list is done after it filled by me.

What do you think is the best data structure for this requirement?

Thanks

You should return a readonly collection. Take a look at
ReadOnlyCollection , it's in System.Collections.ObjectModel

I think it is part of 3.0+, I need to support .NET 2.0... suggestions?

Why not use an ArrayList internally and then convert the ArrayList to an
array and return that?

Kip

[Jon Skeet [C# MVP]]

On Oct 16, 5:04*pm, puzzlecracker <[e-mail]:

You should return a readonly collection. Take a look at
ReadOnlyCollection , it's in System.Collections.ObjectModel

I think it is part of 3.0+, I need to support .NET 2.0... suggestions?

What makes you think that? From MSDN:
http://msdn.microsoft.com/en-us/library/ms132474.aspx

<quote>
Version Information
..NET Framework
Supported in: 3.5, 3.0, 2.0
</quote>

Jon

[puzzlecracker]

On Oct 16, 12:41*pm, "Jon Skeet [C# MVP]" <[e-mail]:

On Oct 16, 5:04*pm, puzzlecracker <[e-mail]:

You should return a readonly collection. Take a look at
ReadOnlyCollection , it's in System.Collections.ObjectModel

I think it is part of 3.0+, I need to support .NET 2.0... suggestions?

What makes you think that? From MSDN:http://msdn.microsoft.com/en-us/library/ms132474.aspx

<quote>
Version Information
.NET Framework
Supported in: 3.5, 3.0, 2.0
</quote>

Jon

I was wrong, it's supported... I first encountered it in the book
on .Net 3.0, hence the erroneous assumption.

[Rudy Velthuis]

Mythran wrote:

Why not use an ArrayList internally and then convert the ArrayList to
an array and return that?

Perhaps because "converting the ArrayList to an array" would mean
copying data from the ArrayList to the array, perhaps even multiple
times, and that is relatively slow, if compared to giving people direct
(but readonly) access.

--
Rudy Velthuis http://rvelthuis.de

"We totally deny the allegations, and we are trying to identify
the allegators."

[puzzlecracker]

On Oct 16, 2:22*pm, "Rudy Velthuis" <[e-mail]:

Mythran wrote:

Why not use an ArrayList internally and then convert the ArrayList to
an array and return that?

Perhaps because "converting the ArrayList to an array" would mean
copying data from the ArrayList to the array, perhaps even multiple
times, and that is relatively slow, if compared to giving people direct
(but readonly) access.

--
Rudy Velthuis * * * *http://rvelthuis.de

"We totally deny the allegations, and we are trying to identify
*the allegators."

Does arraylist uses a traditional array and List uses nodes to store
elements, much like in Java?

[Peter Duniho]

On Thu, 16 Oct 2008 11:41:42 -0700, puzzlecracker <ir*********@gmail.com>
wrote:

Does arraylist uses a traditional array and List uses nodes to store
elements, much like in Java?

ArrayList, List<T>, and Java's ArrayList all use arrays to store elements.

[Rudy Velthuis]

puzzlecracker wrote:

Does arraylist uses a traditional array and List uses nodes to store
elements, much like in Java?

No, List<Tis simply the generic equivalent of ArrayList. Both
internally use an array to hold the list elements. But ArrayList uses
an array of objects, while List<Tuses an array of instances of type T.

--
Rudy Velthuis http://rvelthuis.de

"Barabási's Law of Programming: Program development ends when the
program does what you expect it to do — whether it is correct or
not." -- Albert-László Barabási

[Rudy Velthuis]

Peter Duniho wrote:

On Thu, 16 Oct 2008 11:41:42 -0700, puzzlecracker
<ir*********@gmail.com wrote:

Does arraylist uses a traditional array and List uses nodes to
store elements, much like in Java?

ArrayList, List<T>, and Java's ArrayList all use arrays to store
elements.

Quite right, but I guess he meant that Java's List class is in fact
implemented as a doubly linked list.

--
Rudy Velthuis http://rvelthuis.de

"No Sane man will dance." -- Cicero (106-43 B.C.)

[Peter Duniho]

On Thu, 16 Oct 2008 12:01:30 -0700, Rudy Velthuis
<ne********@rvelthuis.dewrote:

Peter Duniho wrote:

>On Thu, 16 Oct 2008 11:41:42 -0700, puzzlecracker
<ir*********@gmail.com wrote:

Does arraylist uses a traditional array and List uses nodes to
store elements, much like in Java?

ArrayList, List<T>, and Java's ArrayList all use arrays to store
elements.

Quite right, but I guess he meant that Java's List class is in fact
implemented as a doubly linked list.

Java doesn't have a List class. It does have a doubly-linked list class
called LinkedList, and like the ArrayList class it does implement the List
interface. But "puzzlecracker" didn't mention any LinkedList class at
all, in Java or C#.

In any case, it's my hope that my reply answered his question, in spite of
the inaccuracies in that question.

Pete

[Rudy Velthuis]

Peter Duniho wrote:

Quite right, but I guess he meant that Java's List class is in fact
implemented as a doubly linked list.

Java doesn't have a List class. It does have a doubly-linked list
class called LinkedList,

Hmmm... then I must be confusing it with one of the many other
frameworks I have seen lately. <g>

Sorry.

--
Rudy Velthuis http://rvelthuis.de

"A low voter turnout is an indication of fewer people going to
the polls." -- George W. Bush

[Ben Voigt [C++ MVP]]

Rudy Velthuis wrote:

Peter Duniho wrote:

>>Quite right, but I guess he meant that Java's List class is in fact
implemented as a doubly linked list.

Java doesn't have a List class. It does have a doubly-linked list
class called LinkedList,

Hmmm... then I must be confusing it with one of the many other
frameworks I have seen lately. <g>

C++ std::list<typename Tis a linked list like C# LinkedList<T>.
C++ std::vector<typename Tis a wrapped array like ArrayList or List<T>.

>
Sorry.

[Rudy Velthuis]

Ben Voigt [C++ MVP] wrote:

Rudy Velthuis wrote:

Peter Duniho wrote:

Quite right, but I guess he meant that Java's List class is in
fact implemented as a doubly linked list.
>
Java doesn't have a List class. It does have a doubly-linked list
class called LinkedList,

Hmmm... then I must be confusing it with one of the many other
frameworks I have seen lately. <g>

C++ std::list<typename Tis a linked list like C# LinkedList<T>.

Ah, indeed. I guess I was indeed thinking of std::list<T>.
--
Rudy Velthuis http://rvelthuis.de

"Imagine if every Thursday your shoes exploded if you tied them
the usual way. This happens to us all the time with computers,
and nobody thinks of complaining." -- Jeff Raskin