Confused about Hashtable and ForEach..

stokerfed · June 13th, 2007, 12:10 PM

I declared a hashtable of IssueType objects. An IssueType object is initialized with a string NAME and a integer ID. The function "makeXmlSenseOfData()" is supposed to access all the elements in the hashtable, and call a set function within the object, but I'm getting a runtime error...

Quote:

quote:
Message: Specified cast is not valid.
at Project.xmlHandler.makeXmlSenseOfData():line 94
-Which is pointing to the line "foreach(IssueType issue in _issueTypes)"

Code:

_issueTypes.Add("Bug", new Project.IssueType("Bug",1));
            _issueTypes.Add("New Feature", new Project.IssueType("New Feature",2)); 
            _issueTypes.Add("Task", new Project.IssueType("Task",3));


public void makeXmlSenseOfData()
        {
            System.Xml.XmlNodeList issueTypeList = null;
            foreach(IssueType issue in _issueTypes)
            {
                issueTypeList = xmlData.SelectNodes("//type[@id=" + issue.getTypeID() + "]");
                if(issueTypeList.Count != 0)
                {
                    issue.setCount(issueTypeList.Count);
                    issue.isInProject();
                }
            }
        }

Any ideas??

maulik33 · June 13th, 2007, 12:50 PM

try
foreach(string Issue in _issueTypes.keys)

stokerfed · June 13th, 2007, 12:55 PM

Thanks for the reply...

That won't work because I need to use the "setCount()" and "isInProject()" functions of the IssueType class in lines:

Code:

issue.setCount(issueTypeList.Count);
issue.isInProject();

Is I change it to string, I get a error because those functions are not defined there..

stokerfed · June 13th, 2007, 01:07 PM

Pretty much, I have a hashtable of objects, and I don't know if those objects are still there when I try to reference the functions in them...

Code:

_issueTypes.Add("Bug", new Project.IssueType("Bug",1));
_issueTypes.Add("New Feature", new Project.IssueType("New Feature",2)); _issueTypes.Add("Task",new Project.IssueType("Task",3));

Are these objects still there later on in the program??

I'm using Visual Studio, so when you hit the "." button, all the functions should appear from a selection dropdown.. I type this:

Code:

_issueTypes["Bug"].

and it only shows "Equals" "GetHashCode" "GetType" "ToString" when I'm expecting to see all of the functions from my IssueType class...

planoie · June 13th, 2007, 02:53 PM

The type exposed by the HashTable indexer is System.Object. "Equals", "GetHashCode", "GetType" & "ToString" are members of System.Object. You need to cast each value within the hash table collection to your type in order to access that type's members.

((Project.IssueType)_issueTypes["Bug"]).<IssueType member>

If you are in .NET 2.0, I'd recommend avoiding the hash table. Instead you could use the generic Dictionary:

System.Collections.Generic.Dictionary<string, Project.IssueType> _issueTypes;

All the methods involving keys and values of the dictionary will be typed to string and Project.IssueType respectively. When you iterate thru the list, you will be working with the explicit type defined for the dictionary. The indexer will return Project.IssueType so you can directly access the type's members.

-Peter