Question

Can anybody explain why the if statement below evaluates false?

public void addShapeToWhiteboard(PolyLine shape)
{
   Window.alert("2");
   if(shape instanceof PolyLine)
   {
      Window.alert("3");
      this.whiteboard.add((PolyLine)shape);
      Window.alert("3.5");
   }    
   this.whiteboard.draw();
   Window.alert("4");
}

it takes in a “PolyLine” object, but instanceof returns false because I get an alert of “2” followed by an alert of “4” and have no clue how it’s even possible.

Answer 1

Maybe shape is null? instanceof returns false in such a case.