Question

I have the interface:

 public interface IProcess
    {
        void Step_One();
        void Step_Two();
        Timer ProcessTimer{get; set;}
    }

the base class..

 public class ProcessBase
    {
        protected Timer processTimer;
        public Timer ProcessTimer{get{ return processTimer;}set{processTimer=value;}}



        //sets up all the common objects
        public ProcessBase() 
        {


        }

        //This constructor will call the default constructor ^
        protected ProcessBase(long intervalArg) : this()
        {
            processTimer = new Timer(intervalArg);
            processTimer.Enabled = true;

        }

    }

the concrete class

public class ReportedContentProcess : ProcessBase, IProcess
{

    public ReportedContentProcess(): base(5000)
    {

    }

    public void Step_One()
    {
    }

    public void Step_Two()
    {
    }
}

but when I try and get it out in a factory…

public static class ProcessFactory
    {

        public static List<IProcess> GetProcessors()
        {

            ReportedContentProcess.ReportedContentProcess reportedContentProcess = new ReportedContentProcess.ReportedContentProcess();

            List<IProcess> retProcesses = new List<IProcess>();
            retProcesses.Add(reportedContentProcess);
            return retProcesses;

        }   
    }

and then attach a handler to the timer…

processorsForService = ProcessFactory.GetProcessors();


                foreach(IProcess p in processorsForService)
                {
                    p.ProcessTimer.Elapsed += new ElapsedEventHandler(IProcess_Timer_Elapsed);
                }

I get a run-time error saying that the p.ProcessTimer is null. Why is this? I have inherited and instantiated in the base class cant understand why its null. Ive even included it in the interface…

Answer 1

I see that you’re initializing Timer in second constructor only. What if the default one is called (i.e. the constructor that is without params)?