We know the information required for each of the shapes to achieve our goals. Now, we have to design the classes to include the necessary fields that provide the required data to each instance. We have to make sure that each class has the necessary fields that encapsulate all the data required by the objects to perform all the tasks based on our application domain.
Let's start with the Circle class. We need to know the radius for each instance of this class, that is, for each circle object. Thus, we need an encapsulated variable that allows each instance of the Circle class to specify the value for the radius.
Note
The variables defined in a class to encapsulate the data for each instance of the class in Java 9 are known as fields. Each instance has its own independent value for the fields defined in the class. The fields allow us to define the characteristics for an instance of the class. In other programming languages that support object-oriented principles...