Interfaces and type checking

Question

this is a stupid question but if i implement an interface its constructor would assign the objects that have been used as its arguments to the instance variables these objects are the
classes that implement that interface, the constructor knows nothing about these objects only that they sure to work because they implement that interface.
does this bypass typechecking because the object passed to the interface have implemented that interface or am i way off.
sorry if this is hard to understand but im a bit confused.

Answer 1

I'm beyond a bit confused... I'm a lot confused.
An interface just defines the "controls"... accelerate, brake, turn.
A class implements that interface... com.ford.Truck implements std.trans.Drivable, as does com.gmh.Car (barely;-)... note also that the car and the truck are manufactured by independent (indeed competing) organisations, and that the Interface is defined by an imaginary international transport standards body.
The interface allows different classes to be manipulated by their common "standard" interface... so if (motorway.isBlocked) {
  // there's a prang on the motorway, so stop everything (cars, trucks & bikes).
  for (Drivable vehicle : motorway.getTraffic()) {
    vehicle.brake(Drivable.MAXIMUM_BRAKING);
}Hope that helps.
Edited by: corlettk on Jan 21, 2008 1:43 PM