C# event handling (compared to Java)

Question

I am currently having a hardtime understanding and implementing events in C# using delagates. I am used to the Java way of doing things:

1. Define an interface f

Answer 1

In c# events are delegates. They behave in a similar way to a function pointer in C/C++ but are actual classes derived from System.Delegate.

In this case, create a custom EventArgs class to pass the Computer object.

public class ComputerEventArgs : EventArgs
{
  private Computer _computer;

  public ComputerEventArgs(Computer computer) {
    _computer = computer;
  }

  public Computer Computer { get { return _computer; } }
}

Then expose the events from the producer:

public class ComputerEventProducer
{
  public event EventHandler Started;
  public event EventHandler Stopped;
  public event EventHandler Reset;
  public event EventHandler Error;

  /*
  // Invokes the Started event */
  private void OnStarted(Computer computer) {
    if( Started != null ) {
      Started(this, new ComputerEventArgs(computer));
    }
  }

  // Add OnStopped, OnReset and OnError

}

The consumer of the events then binds a handler function to each event on the consumer.

public class ComputerEventConsumer
{
  public void ComputerEventConsumer(ComputerEventProducer producer) {
    producer.Started += new EventHandler(ComputerStarted);
    // Add other event handlers
  }

  private void ComputerStarted(object sender, ComputerEventArgs e) {
  }
}

When the ComputerEventProducer calls OnStarted the Started event is invoked which in turn will call the ComputerEventConsumer.ComputerStarted method.