Example for the design of a class: representation for the objects

We have to decide how to represent the properties of cars. In this case, it is immediate to choose the representation. We represent the objects of the class Car by means of the following instance variables:

• the plate, by means of an instance variable plate of type String
• the model, by means of an instance variable model of type String
• the color, by means of an instance variable color of type String
• the owner, by means of an instance variable owner of type Person

Note: In our initial examples, the choice of the representation will always be immediate. However, as we go on with the course, we will see that this step can become significantly more complex.

At this point we are ready to write:

public class Car {
  // representation of the objects
  private String plate;
  private String model;
  private String color;
  private Person owner;

  // public methods realizing the requested functionalities
}