Question about dealing with Arraylists in c#

Question

I made a static function that returns me an ArrayList of objects:

 allThread =(ArrayList) AllQuestionsPresented.GetAllThreads();

Now the objects have properties that i want to get out. But I noticed that i cant type allThreads.Name...or allThreads["Name"] , or allThreads[1], it wont give me the object itself. Cause intellisense doesnt recognize it..

Here is what I am trying to do..:

That function is in one class:

    public static ICollection GetAllThreads()
{
    ArrayList allThreads = new ArrayList();
    string findUserID = "SELECT UserID FROM Users";
    string myConnectionString = AllQuestionsPresented.connectionString;

    using (SqlConnection myConnection = new SqlConnection(myConnectionString))
    {
        SqlCommand sqlCommand = new SqlCommand(findUserID, myConnection);
        SqlDataReader reader = sqlCommand.ExecuteReader();
        while (reader.Read())
        {
            AllQuestionsPresented allQ = new AllQuestionsPresented((Guid)reader["UserID"]);
            allThreads.Add(allQ);
        }
    }
    return allThreads;
}

That is some code from another function in another class:

    forumsPages = new Dictionary<int, List<DisplayAllQuestionsTable>>();
    allThread =(ArrayList) AllQuestionsPresented.GetAllThreads();//I want to convert the ICollection


    for (int i = 0; i < 20; i++)
    {
        threads.Add(new DisplayAllQuestionsTable(allThread[i].//And use it here. I want an object to be returned..same object that was stored in the ArrayList in the static function

    }

Yuck · Accepted Answer · 2011-06-07 17:57:38Z

2

I think what you need to use is a generic version, List<T> where T would be of type AllQuestionsPresented. That should enable IntelliSense for you as you're expecting.

Can you post the definition for AllQuestionsPresented?

answered Jun 7, 2011 at 17:57

Yuck

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1 Comment

Matrix001 Over a year ago

It is a class with properties..e.g. public string Name, public string Surname, public int age..nothing important

Maziar Taheri · Accepted Answer · 2011-06-07 17:59:32Z

1

USE A List:

 public static List<AllQuestionsPresented> GetAllThreads()
{
    List<AllQuestionsPresented> allThreads = new List<AllQuestionsPresented>();
    string findUserID = "SELECT UserID FROM Users";
    string myConnectionString = AllQuestionsPresented.connectionString;

using (SqlConnection myConnection = new SqlConnection(myConnectionString))
    {
        SqlCommand sqlCommand = new SqlCommand(findUserID, myConnection);
        SqlDataReader reader = sqlCommand.ExecuteReader();
        while (reader.Read())
        {
            AllQuestionsPresented allQ = new AllQuestionsPresented((Guid)reader["UserID"]);
            allThreads.Add(allQ);
        }
    }
    return allThreads;
}

answered Jun 7, 2011 at 17:59

Maziar Taheri

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Comments

Brad Divine · Accepted Answer · 2011-06-07 17:59:06Z

1

ArrayList only holds collections of objects; you'd have to cast allThread[i] to an AllQuestionsPresented.

You might look at using generic collections, but you'd probably have to refactor your architecture a bit to handle it.

answered Jun 7, 2011 at 17:59

Brad Divine

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Matrix001 Over a year ago

oooh, i see.. i would better resort to ArrrayList

Security Hound · Accepted Answer · 2011-06-07 18:00:13Z

1

1) ArrayList contains objects so the property of an object can be accessed without casting the object.

Having a Dictionary full of objects is sort of pointless, I would cast the objects into type that is actually helpful, and has the properties you want. This would require to change the way your select statement works.

Honestly there is no need for the ArrayList, you can write the select statement, to fill the collection you want to use instad.

answered Jun 7, 2011 at 18:00

Security Hound

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Comments

Andrew T Finnell · Accepted Answer · 2011-06-07 18:09:38Z

Or use LINQ

[Table(Name="Users")]
class User
{
   [Column]
   public Guid UserId;
}  

IEnumerable<User> questions;
using (SqlConnection myConnection = new SqlConnection(myConnectionString))
{
    var dc = new DataContext(myConnection);
   // Use ToArray to force all reads on the connection
    questions = 
        (from user in dc.GetTable<User>() 
        select new AllQuestionsPresented(user.UserId)).ToArray()
}

var threads = 
       from question in questions 
       select new DisplayAllQuestionsTable(question.SomeProperty);

Or if you are sadistic

var threads = 
       from question in (
            from user in dc.GetTable<User>() 
            select new AllQuestionsPresented(user.UserId) )
       select new DisplayAllQuestionsTable(question.SomeProperty);

Vincent Koeman · Accepted Answer · 2011-06-07 17:56:29Z

0

Why use an ARRAYlist? You could just use the much better suited

   List<objecttype here>

With this data structure you can acces everything the way you want (with the square brackets). Even the ICollection thing is quite useless.

answered Jun 7, 2011 at 17:56

Vincent Koeman

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