Accessing values in custom class stored in ArrayList

[Jason Salas]

Hi everyone,

How would I access the properties of a custom class I've developed once
instances of that class are added within a .NET collection, specifically an
ArrayList?

Here's what I'm doing:

public class Order
{
private string fname,lname;
public string FName { get { return fname; } }
public string LName { get { return lname; } }

public Order(string first,string last)
{
this.fname = first;
this.lname = last;
}
}

ArrayList arr = new ArrayList();
arr.Add(new Order("Jason","Salas"));
arr.Add(new Order("Bart","Simpson"));
arr.Add(new Order("Andrew","Dice Clay"));

My question is how would I programmatically get a refernence to one of the
Order objects in arr, so that I access and use its propety values?

I'm not sure this would work:

for(i=0;i<arr.Length-1;i++)
{
(Order)arr[i].FName;
}

Got any ideas?

Thanks!
Jas

[Russell Jones]

The ArrayList returns a generic Object reference. Your code would try to
cast the return value of the Object.FName method to an Order. You just need
some more parentheses . Also, the ArrayList isn't an Array, and doesn't
have a Length method. It's a collection type, and has a Count method
instead. For example

for(int i=0;i<arr.Count-1;i++)
{
Console.Out.WriteLine(((Order)arr[i]).FName);
}

"Jason Salas" <jason@kuam.com> wrote in message
news:3f27a665$1@tnews.web.devx.com...
> Hi everyone,
>
> How would I access the properties of a custom class I've developed once
> instances of that class are added within a .NET collection, specifically
an
> ArrayList?
>
> Here's what I'm doing:
>
> public class Order
> {
> private string fname,lname;
> public string FName { get { return fname; } }
> public string LName { get { return lname; } }
>
> public Order(string first,string last)
> {
> this.fname = first;
> this.lname = last;
> }
> }
>
> ArrayList arr = new ArrayList();
> arr.Add(new Order("Jason","Salas"));
> arr.Add(new Order("Bart","Simpson"));
> arr.Add(new Order("Andrew","Dice Clay"));
>
> My question is how would I programmatically get a refernence to one of the
> Order objects in arr, so that I access and use its propety values?
>
> I'm not sure this would work:
>
> for(i=0;i<arr.Length-1;i++)
> {
> (Order)arr[i].FName;
> }
>
> Got any ideas?
>
> Thanks!
> Jas
>
>

[Jason Salas]

Oops....thanks again Russ!


"Russell Jones" <arj1@nospam.northstate.net> wrote in message
news:3f27d9ca$1@tnews.web.devx.com...
> The ArrayList returns a generic Object reference. Your code would try to
> cast the return value of the Object.FName method to an Order. You just
need
> some more parentheses . Also, the ArrayList isn't an Array, and doesn't
> have a Length method. It's a collection type, and has a Count method
> instead. For example
>
> for(int i=0;i<arr.Count-1;i++)
> {
> Console.Out.WriteLine(((Order)arr[i]).FName);
> }
>
> "Jason Salas" <jason@kuam.com> wrote in message
> news:3f27a665$1@tnews.web.devx.com...
> > Hi everyone,
> >
> > How would I access the properties of a custom class I've developed once
> > instances of that class are added within a .NET collection, specifically
> an
> > ArrayList?
> >
> > Here's what I'm doing:
> >
> > public class Order
> > {
> > private string fname,lname;
> > public string FName { get { return fname; } }
> > public string LName { get { return lname; } }
> >
> > public Order(string first,string last)
> > {
> > this.fname = first;
> > this.lname = last;
> > }
> > }
> >
> > ArrayList arr = new ArrayList();
> > arr.Add(new Order("Jason","Salas"));
> > arr.Add(new Order("Bart","Simpson"));
> > arr.Add(new Order("Andrew","Dice Clay"));
> >
> > My question is how would I programmatically get a refernence to one of
the
> > Order objects in arr, so that I access and use its propety values?
> >
> > I'm not sure this would work:
> >
> > for(i=0;i<arr.Length-1;i++)
> > {
> > (Order)arr[i].FName;
> > }
> >
> > Got any ideas?
> >
> > Thanks!
> > Jas
> >
> >
>
>

[Ed Courtenay]

Of course you might find that it's simply easier to iterate over the the
array using foreach:

using System;
using System.Collections;

public class Order
{
private string fname,lname;
public string FName { get { return fname; } }
public string LName { get { return lname; } }

public Order(string first,string last)
{
this.fname = first;
this.lname = last;
}
}


public class Test
{
public static void Main() {
ArrayList arr = new ArrayList();
arr.Add(new Order("Jason","Salas"));
arr.Add(new Order("Bart","Simpson"));
arr.Add(new Order("Andrew","Dice Clay"));


foreach (Order order in arr) {
Console.WriteLine(String.Format("{0} {1}", new object[] {
order.FName,
order.LName
}));
}
}
}


"Russell Jones" <arj1@nospam.northstate.net> wrote in message
news:3f27d9ca$1@tnews.web.devx.com...
> The ArrayList returns a generic Object reference. Your code would try to
> cast the return value of the Object.FName method to an Order. You just
need
> some more parentheses . Also, the ArrayList isn't an Array, and doesn't
> have a Length method. It's a collection type, and has a Count method
> instead. For example
>
> for(int i=0;i<arr.Count-1;i++)
> {
> Console.Out.WriteLine(((Order)arr[i]).FName);
> }
>
> "Jason Salas" <jason@kuam.com> wrote in message
> news:3f27a665$1@tnews.web.devx.com...
> > Hi everyone,
> >
> > How would I access the properties of a custom class I've developed once
> > instances of that class are added within a .NET collection, specifically
> an
> > ArrayList?
> >
> > Here's what I'm doing:
> >
> > public class Order
> > {
> > private string fname,lname;
> > public string FName { get { return fname; } }
> > public string LName { get { return lname; } }
> >
> > public Order(string first,string last)
> > {
> > this.fname = first;
> > this.lname = last;
> > }
> > }
> >
> > ArrayList arr = new ArrayList();
> > arr.Add(new Order("Jason","Salas"));
> > arr.Add(new Order("Bart","Simpson"));
> > arr.Add(new Order("Andrew","Dice Clay"));
> >
> > My question is how would I programmatically get a refernence to one of
the
> > Order objects in arr, so that I access and use its propety values?
> >
> > I'm not sure this would work:
> >
> > for(i=0;i<arr.Length-1;i++)
> > {
> > (Order)arr[i].FName;
> > }
> >
> > Got any ideas?
> >
> > Thanks!
> > Jas
> >
> >
>
>

[Jason Salas]

Hi Ed,

Thanks for the help. There's a discussion going on about this right now in
the ASPAdvice mailing lists, where the theory seems to be upon examination
of the resultant IL, foreach... takes up to 50-200% longer to execute than a
for.. loop. Pretty interesting stuff. I can send you the note that
documented this, if you like.

Jas



"Ed Courtenay" <replace-this-with-my-first-name@edcourtenay.co.uk> wrote in
message news:3f28d6f2$1@tnews.web.devx.com...
> Of course you might find that it's simply easier to iterate over the the
> array using foreach:
>
> using System;
> using System.Collections;
>
> public class Order
> {
> private string fname,lname;
> public string FName { get { return fname; } }
> public string LName { get { return lname; } }
>
> public Order(string first,string last)
> {
> this.fname = first;
> this.lname = last;
> }
> }
>
>
> public class Test
> {
> public static void Main() {
> ArrayList arr = new ArrayList();
> arr.Add(new Order("Jason","Salas"));
> arr.Add(new Order("Bart","Simpson"));
> arr.Add(new Order("Andrew","Dice Clay"));
>
>
> foreach (Order order in arr) {
> Console.WriteLine(String.Format("{0} {1}", new object[] {
> order.FName,
> order.LName
> }));
> }
> }
> }
>
>
> "Russell Jones" <arj1@nospam.northstate.net> wrote in message
> news:3f27d9ca$1@tnews.web.devx.com...
> > The ArrayList returns a generic Object reference. Your code would try to
> > cast the return value of the Object.FName method to an Order. You just
> need
> > some more parentheses . Also, the ArrayList isn't an Array, and
doesn't
> > have a Length method. It's a collection type, and has a Count method
> > instead. For example
> >
> > for(int i=0;i<arr.Count-1;i++)
> > {
> > Console.Out.WriteLine(((Order)arr[i]).FName);
> > }
> >
> > "Jason Salas" <jason@kuam.com> wrote in message
> > news:3f27a665$1@tnews.web.devx.com...
> > > Hi everyone,
> > >
> > > How would I access the properties of a custom class I've developed
once
> > > instances of that class are added within a .NET collection,
specifically
> > an
> > > ArrayList?
> > >
> > > Here's what I'm doing:
> > >
> > > public class Order
> > > {
> > > private string fname,lname;
> > > public string FName { get { return fname; } }
> > > public string LName { get { return lname; } }
> > >
> > > public Order(string first,string last)
> > > {
> > > this.fname = first;
> > > this.lname = last;
> > > }
> > > }
> > >
> > > ArrayList arr = new ArrayList();
> > > arr.Add(new Order("Jason","Salas"));
> > > arr.Add(new Order("Bart","Simpson"));
> > > arr.Add(new Order("Andrew","Dice Clay"));
> > >
> > > My question is how would I programmatically get a refernence to one of
> the
> > > Order objects in arr, so that I access and use its propety values?
> > >
> > > I'm not sure this would work:
> > >
> > > for(i=0;i<arr.Length-1;i++)
> > > {
> > > (Order)arr[i].FName;
> > > }
> > >
> > > Got any ideas?
> > >
> > > Thanks!
> > > Jas
> > >
> > >
> >
> >
>
>