Use Car as an example of an interface because students agree on the general behaviors of a car but can only come up with specific instantiations of cars, which provides students with a strong mental model for interface relationships.

  • It is really important to provide students with tangible motivation for interfaces and inheritance.
  • Activity:
    • Ask a student to draw a "general car."
    • They’ll quickly realize (or you’ll point out) that you’re not drawing a general car. Rather they are drawing a specific car! (a Bug, a Jeep, etc.)
      • Connect this realization to the idea of interfaces.
    • Make interfaces intuitive by explaining that you can never really have a general car, but there is shared behaviors (i.e. methods) for cars.
      • Additionally, cars wouldn’t be an abstract class because the internal components of a car might have no similarity.
    • Then, create sample code for the interface Car and an inheriting class like the following:
      • public interface Car{
            String brand, model;
            double speed;
            int xCoord, int yCorod;
            public void move();
      • public class OffRoadCar implements Car{
            boolean bikeRack=true;
            public void move(){

More about this tip

External Source

Interview with Elissa Redmiles.