Whenever you have to solve a problem in the real world, you use elements and interact with them. For example, when you are thirsty, you take a glass, fill it up with water, soda, or your favorite juice, and then you drink. Similarly, you can easily recognize elements, known as objects, from real-world scenarios and then translate them into object-oriented code. We will start learning the principles of object-oriented programming to use them in the Java 9 programming language to develop any kind of applications.

Now, we will imagine we have to develop a RESTful Web Service that will be consumed by mobile apps and a web application. These apps and applications will have different user interfaces and diverse user experiences. However, we don't have to worry about these differences because we will be focused on the Web Service, that is, we will be backend developers.

Artists use different combinations of geometric shapes and organic shapes to...