We can define a setter method that transforms a received value to a valid value for a related field. The getter method would just need to return the value of the related field. The user will only be able to work with the setter and getter methods and our related field will always have a valid value. This way, we can make sure that whenever we require the value, we will retrieve a valid value.

Each virtual creature has a visibility level that determines how easy it is for anybody to visualize the virtual creature's body. We will add a private visibilityLevel field, a setVisibility method, and a getVisibility method. We will change the constructor code to call the setVisiblity method to set an initial value for the visibilityLevel field.

We want to make sure that the visibility level is a number from 0 to 100 (inclusive). Thus, we will code the setter method to transform the values lower than 0 to 0 and values higher than 100 to 100. The setVisibility...