Question

我有界面：

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

基类..

 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;

        }

    }

具体课程

public class ReportedContentProcess : ProcessBase, IProcess
{

    public ReportedContentProcess(): base(5000)
    {

    }

    public void Step_One()
    {
    }

    public void Step_Two()
    {
    }
}

但是当我尝试在工厂里把它拿出来时......

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;

        }   
    }

然后将处理程序附加到计时器...

processorsForService = ProcessFactory.GetProcessors();


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

我收到运行时错误，说p.ProcessTimer为null。为什么是这样？我在基类中继承并实例化了解为什么它的null。我甚至把它包含在界面中......

Answer 1

我看到你只是在第二个构造函数中初始化Timer。如果调用默认值（即没有参数的构造函数）怎么办？

当我继承它时，为什么我的Timer会返回null？

1 个答案: