Want a key value collection that maintains ordering

[illegal.prime]

Hi all, is there a key value collection in .Net that maintains the
ordering in which I add items.

I'm finding that I'm creating a number of classes that contain a name
and then some object. I would prefer just to use some collection that
maintains the ordering in which I add things (like ArrayList), but that
maps a key to a value.

I thought NameValueCollec tion was the right one - but it doesn't
guarantee ordering.

If it doesn't exist, why not? If it doesn't what is the "right" way to
build it? Just have wrap your class around an instance of ArrayList
and have some internal class that takes the key given in the Add method
and instantiates this generic class with two members (a string key and
an object value), then add that to the internal ArrayList?

Thanks,
Novice

[Bruce Wood]

I would create a class that wraps an ArrayList and a Hashtable.
Whenever anything is added to your class, add it to both the ArrayList
and the Hashtable. When you want to return an iterator, return an
iterator into the ArrayList. When you want a lookup by key, look it up
in the Hashtable.

[illegal.prime]

I was actually thinking of doing something like that originally since
it is all reference based, there would be minimal cost (memory) to do
something like that - i.e. to have the ArrayList and the Hashtable to
point to the various elements.

Does anyone know of any reason why I should just rip off the
implementation of PhoneNumberDict ionary (that extends DictionaryBase)
from here:
http://www.codeproject.com/csharp/collection1.asp

I'm not doing a PhoneNumberDict ionary, but it seems to provide what I
want in terms of allowing me to specify an arbitrary name and an
arbitrary object. And when I get them all, they will be returned in
the order I added them.

Does that sound right?

Thanks,
Novice

[illegal.prime]

Crud!

I've tried using DictionaryBase, but the compiler gives me
DictionaryBase could not be found. I guess that means it is a .Net 2
class?

That sucks.

[illegal.prime]

Never mind - looks like the executable wasn't getting regenerated or
something - fresh build and the compiler was okay with it.

[illegal.prime]

Well, this doesn't work, it doesn't maintain the order in which I added
them when I iterate through it.

So I guess I will just do something like (not compileable code):
class DictionaryEntry Collection
{
private ArrayList mKeyValues;

public DictionaryEntry Collection()
{
mKeyValues = new ArrayList();
}

public void Add (object key, object value)
{
DictionaryEntry keyValue = new DictionaryEntry (key, value);
mKeyValues.Add( keyValue);
}

public DictionaryEntry[] GetKeyValueElem ents()
{
//iterate over all the elements in my arraylist
}
}

Sound right?

Thanks,
Novice

[jeremiah johnson]

Bruce Wood wrote:

I would create a class that wraps an ArrayList and a Hashtable.
Whenever anything is added to your class, add it to both the ArrayList
and the Hashtable. When you want to return an iterator, return an
iterator into the ArrayList. When you want a lookup by key, look it up
in the Hashtable.

What if you add something with the same key twice? It will show up in
the hashtable just once but in the ArrayList twice. That is probably
not what he's looking for.

I'd create a new collection that wrapped an ArrayList<Objec t[]> and
massage the add method to check for duplicates, while maintaining order.

I just whipped something up in Java. Its untested, unsynchronized,
probably slow, and the syntax is slightly different for C# (the for
loop). Here it is; it might help you, it might not.

public class HashList {

private ArrayList<Objec t[]> coll;

public HashList() {
coll = new ArrayList<Objec t[]>();
}

public void add(Object key, Object value) {
boolean alreadyAdded = false;

for (Object[] s : coll) {
if (s[0] == key) {
int me = coll.indexOf(s) ;
coll.remove(me) ;
coll.add(me, s);
alreadyAdded = true;
}
}

if (!alreadyAdded) {
coll.add(new Object[] { key, value });
}
}

}

[Nicholas Paldino [.NET/C# MVP]]

Novice,

You can just use the SortedList<TKey , TValue> generic class. It will
allow you to perform lookups, and order the list as well.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

<il***********@ gmail.com> wrote in message
news:11******** **************@ j73g2000cwa.goo glegroups.com.. .

Hi all, is there a key value collection in .Net that maintains the
ordering in which I add items.

I'm finding that I'm creating a number of classes that contain a name
and then some object. I would prefer just to use some collection that
maintains the ordering in which I add things (like ArrayList), but that
maps a key to a value.

I thought NameValueCollec tion was the right one - but it doesn't
guarantee ordering.

If it doesn't exist, why not? If it doesn't what is the "right" way to
build it? Just have wrap your class around an instance of ArrayList
and have some internal class that takes the key given in the Add method
and instantiates this generic class with two members (a string key and
an object value), then add that to the internal ArrayList?

Thanks,
Novice

[MSDN]

Nicholas,

new to Generics, is SortedList already generic?

Why can I ! say SortedList<stri ng,string> ??? Throws Error
if (!Page.IsPostBa ck)
{
AlwaysSortedLis t = new SortedList();
Session.Add("AS L",AlwaysSorted List);
}

in button handler....

((SortedList)Se ssion["ASL"]).Add(TextBox1. Text,TextBox1.T ext);
DropDownList1.D ataSource = ((SortedList)Se ssion["ASL"]); //AlwaysSortedLis t;
DropDownList1.D ataTextField = "key";
DropDownList1.D ataValueField = "value";
DropDownList1.D ataBind();

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c om> wrote in
message news:%2******** **********@TK2M SFTNGP04.phx.gb l...

Novice,

You can just use the SortedList<TKey , TValue> generic class. It will
allow you to perform lookups, and order the list as well.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

<il***********@ gmail.com> wrote in message
news:11******** **************@ j73g2000cwa.goo glegroups.com.. .

Hi all, is there a key value collection in .Net that maintains the
ordering in which I add items.

I'm finding that I'm creating a number of classes that contain a name
and then some object. I would prefer just to use some collection that
maintains the ordering in which I add things (like ArrayList), but that
maps a key to a value.

I thought NameValueCollec tion was the right one - but it doesn't
guarantee ordering.

If it doesn't exist, why not? If it doesn't what is the "right" way to
build it? Just have wrap your class around an instance of ArrayList
and have some internal class that takes the key given in the Add method
and instantiates this generic class with two members (a string key and
an object value), then add that to the internal ArrayList?

Thanks,
Novice

[Michael D. Ober]

Yes. In VB 2005, you would use

dim AlwaysSortedLis t as new SortedList(of String, String)
AlwaysSortedLis t.add("Key1", "This is Key1")

debug.print(Alw aysSortedList(" Key1") displays "This is Key1" in the
Immediate window.

Mike Ober.

"MSDN" <sq**********@h otmail.com> wrote in message
news:eh******** ******@TK2MSFTN GP04.phx.gbl...

Nicholas,

new to Generics, is SortedList already generic?

Why can I ! say SortedList<stri ng,string> ??? Throws Error
if (!Page.IsPostBa ck)
{
AlwaysSortedLis t = new SortedList();
Session.Add("AS L",AlwaysSorted List);
}

in button handler....

((SortedList)Se ssion["ASL"]).Add(TextBox1. Text,TextBox1.T ext);
DropDownList1.D ataSource = ((SortedList)Se ssion["ASL"]); //AlwaysSortedLis t; DropDownList1.D ataTextField = "key";
DropDownList1.D ataValueField = "value";
DropDownList1.D ataBind();

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c om> wrote in message news:%2******** **********@TK2M SFTNGP04.phx.gb l...

Novice,

You can just use the SortedList<TKey , TValue> generic class. It will
allow you to perform lookups, and order the list as well.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

<il***********@ gmail.com> wrote in message
news:11******** **************@ j73g2000cwa.goo glegroups.com.. .

Hi all, is there a key value collection in .Net that maintains the
ordering in which I add items.

I'm finding that I'm creating a number of classes that contain a name
and then some object. I would prefer just to use some collection that
maintains the ordering in which I add things (like ArrayList), but that
maps a key to a value.

I thought NameValueCollec tion was the right one - but it doesn't
guarantee ordering.

If it doesn't exist, why not? If it doesn't what is the "right" way to
build it? Just have wrap your class around an instance of ArrayList
and have some internal class that takes the key given in the Add method
and instantiates this generic class with two members (a string key and
an object value), then add that to the internal ArrayList?

Thanks,
Novice