将Java移植到Xamarin Android库的C＃

Question

I created an Android Binding Library for my Xamarin project, using an AAR.

I am now trying to implement that library.

Here is the java snippet of code using the library:

The java code:

new AsyncOperation.CompletionHandler<RouteManager>(){
    @Override
    public void success(RouteManager result){
        result.subscribe(ACCEL_DATA, new RouteManager.MessageHandler(){
        @Override
        public void process(Message message){
            Log.i(LOG_TAG,message)
        }
    }
}

I am trying to port this code to C#.

My C# code, from C# wrapper created from binding library:

class AsyncOperationHandler : AsyncOperationCompletionHandler
{
     public override unsafe void Success(Object p0)
     {
          try
          {
               var routeManger = (IRouteManager)p0;
               routeManger.Subscribe(ACCEL_DATA, new RouteMessageHandler());
          }
          catch (Exception)
          {
            Log.Error(LOG_TAG, "Error");
          }
     }
}

class RouteMessageHandler : IRouteManagerMessageHandler
{
      public void Dispose()
      {
          throw new NotImplementedException();
      }
      public IntPtr Handle { get; }
      public void Process(Message p0)
      {
          var message = p0;
          Log.Info(LOG_TAG, message);
      }
}

I am getting an error in the C# wrapper on the routeManger.Subscribe line.

When the RouteManagerMessageHandler gets initialized, it gets the Handle, then throws a null pointer exception inside the Binding Library.

Is this the correct way to port a Java Interface to C#?

Answer 1

If you implement a Java Interface, you have to derive from Java.Lang.Object .

class RouteMessageHandler : Java.Lang.Object, IRouteManagerMessageHandler
{
    public void Process(Message p0)
    {
        var message = p0;
        Log.Info(LOG_TAG, message);
    }
}

There should be something on the compile output.

Type 'AppXYZ.RouteMessageHandler' implements IRouteManagerMessageHandler but does not inherit from Java.Lang.Object. It is not supported.