Q: Casting objects from an ArrayList

[Martin Arvidsson, Visual Systems AB]

Hi!

I am going crayz, i cant get this to work. and i don't know what the problem
is.

I have this method

public ArrayList ResolveData()
{
ArrayList workingList = new ArrayList();


Loop and stuff
// do stuff

workingList.Add(resolvedString.Split(new char[]{';', '--'});
loop ends here

return workingList
}

Then i have this method

private void MyPrivate()
{
ArrayList myArray = ResolveData();

foreach (ArrayList obj in myArray)
{
string[] resultSet = obj as string[]; <<<< This is where i get the
compile error.
}
}

What am i doing wrong?

Regards
Martin

 

[Jon Skeet [C# MVP]]

I am going crayz, i cant get this to work. and i don't know what the problem
is.

What am i doing wrong?

This line:

foreach (ArrayList obj in myArray)

should just be:

foreach (string[] resultSet in myArray)

The way you've got it at the moment is expecting the ArrayList to be
full of other ArrayLists. There's no way of casting an ArrayList to a
string[], which is why you're getting a compile-time error.

Jon

 

[DeveloperX]

Hi!

I am going crayz, i cant get this to work. and i don't know what the problem
is.

I have this method

public ArrayList ResolveData()
{
ArrayList workingList = new ArrayList();

Loop and stuff
// do stuff

workingList.Add(resolvedString.Split(new char[]{';', '--'});
loop ends here

return workingList

}

Then i have this method

private void MyPrivate()
{
ArrayList myArray = ResolveData();

foreach (ArrayList obj in myArray)
{
string[] resultSet = obj as string[]; <<<< This is where i get the
compile error.
}

}

What am i doing wrong?

Regards
Martin

Well you've got ArrayList in your foreach instead of string[]. Try
this:

System.Collections.ArrayList a = new System.Collections.ArrayList();
a.Add("this is a test".Split(' '));
a.Add("this is a test".Split(' '));
string[] s = (string[])a[0]; // <-- example normal cast
foreach(string[] ss in a) // <--- string array
{
Console.WriteLine(ss.Length);
}

 

[Marc Gravell]

Jon and DeveloperX have hopefully answered your original question; as
an additional - if you can, I strongly suggest moving to .Net 2.0 and
using generics, such as List<T>; because this is strongly typed, it
makes it absolutely clear what the problem is *at compile-time*,
rather than having to debug the issue at run-time.

Marc