Confused with ArrayList and Reference types

I have a custom object, EventList that extends ArrayList, and a second custom object, Event, that stores event information and has a constructor that can take a database ID to instantiate itself.

I am trying to write a method for the EventList to fill it with a list of Event objects instantiated from a database.

I am using the following loop

while (dbManager.DataReader.Read())
{
          int intEventID = (int) dbManager.DataReader["EventID"] ;
          this.Add( new Event( intEventID ) );
}

However the this.Add(...) line seems to be updating a reference to the previously added Event Object rather than creating a new instance of an Event object. I am ending up with an array list with a number of references to the same Event object!

Can anyone shed any light on why this is happening, and how I can get around it?

1 Reply

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Alan18y ago
Well, you're clearly creating a new Event object each time around the loop so that can't be the problem.

If you've overridden the ArrayList.Add() method in your EventList class, I'd check that the code is simply adding a new Event object and not changing the existing elements to reference the same object as you've just added.