Converting Java to C# - Override on Instantiation

Question

I'm having difficulty converting the below code from Java to C#.

        this.document.add(new VerticalPositionMark() {
            @Override
            public void draw(final PdfContentByte canvas, final float llx, final float lly, final float urx, final float ury, final float y)
            {
                final PdfTemplate createTemplate = canvas.createTemplate(50, 50);
                Main.this.tocPlaceholder.put(title, createTemplate);

                canvas.addTemplate(createTemplate, urx - 50, y);
            }
        });

I'm not really sure if it's possible to override on instantiation in C#. If there isn't, is there a way to replicate the code to achieve what's needed?

Answer 1

C# doesn't have anonymous classes like we know in Java (they can't extend other classes or implement interfaces). I would suggest you use Lambda expressions, but since you're working with a framework that's not an option.

Consider your starting Java code as the following, which extracts the anonymous inner class to a named class.

public class ContextClass
{
    public void ContextMethod()
    {
      this.document.add(new CustomVerticalPositionMark(title, this.tocPlaceholder));
    }
}

class CustomVerticalPositionMark extends VerticalPositionMark
{
    final String title;
    final PlaceHolder tocPlaceholder;

    CustomVerticalPositionMark(String title, PlaceHolder tocPlaceholder)
    {
        this.title = title;
        this.tocPlaceholder = tocPlaceholder;
    }

   @Override
   public void draw(final PdfContentByte canvas, final float llx, final float lly, final float urx, final float ury, final float y)
   {
       final PdfTemplate createTemplate = canvas.createTemplate(50, 50);
       tocPlaceholder.put(title, createTemplate);

       canvas.addTemplate(createTemplate, urx - 50, y);
   }
}