提出一个简单的事件

Question

我的界面有一个没有参数的事件

public interface IMyInterface
{
     event EventHandler OnSomethingHappened;
}

这是我实现它的方式。

   public class MyBaseClass : IMyInterface
    {
private event EventHandler onSomethingHappened;
public event EventHandler OnSomethingHappened
{
    add
    {
        onSomethingHappened-= value;
        onSomethingHappened+= value;
    }

    remove
    {
        onSomethingHappened-= value;
    }
}
    }

但是当我尝试如下使用它时

if ( MyBaseClassInstance.OnSomethingHappened != null )
        MyBaseClassInstance.OnSomethingHappened();

我收到以下编译错误

事件“ ConsoleApplication1.IMyInterface.OnSomethingHappened”只能出现在+ =或-=的左侧

我究竟做错了什么？

Answer 1

这是您的代码外观：

    public interface IMyInterface
    {
        event EventHandler OnSomethingHappened;
    }

    //implement the interface
    public class MyBaseClass : IMyInterface
    {
        public event EventHandler OnSomethingHappened;

        public void DoSomeLogicWhichRaisesTheEvent()
        {
            if (OnSomethingHappened != null)
            {
                MyBaseClass sender = this;
                var eventArgs = new EventArgs();
                //let all subscibers to event know that the event happened
                OnSomethingHappened(sender, eventArgs);
            }
        }
    }

    public class ConsumerClass
    {
        private IMyInterface myBaseClassInstance;

        public ConsumerClass()
        {
            myBaseClassInstance = new MyBaseClass();
            //attach to the event
            myBaseClassInstance.OnSomethingHappened += MyBaseClassInstance_OnSomethingHappened;
        }

        private void MyBaseClassInstance_OnSomethingHappened(object sender, EventArgs e)
        {
            //react to the raised event
            throw new NotImplementedException();
        }
    }

如您所见，您需要实现IMyInterface接口，并且当MyBaseClass需要引发事件时，可以调用OnSomethingHappened（sender，eventArgs）;。

ConsumerClass是您需要消费或做某事的地方，以应对引发的事件。 您可能会考虑将MyBaseClass重命名为其他名称，而不使用“ Base”，因为它不是抽象类。