Java EE 8 Design Patterns and Best Practices

Single responsibility principle

A microservice should always have a small set of responsibilities. This definition is based on a principle called the single responsibility principle, which states that a class must have only one reason to change. In other words, a class with more than one motive to change would have more responsibilities, and would not be cohesive. This would create problems, such as high coupling between the responsibilities of a class, difficulty in reusing code, and difficult maintenance. 

A class that had methods that are responsible for calculation, as well as methods for formatting the result, would be an example of a class with little cohesion. Let's look at the following example:

class Insurance {     public double calculateCotation ...