Functional Programming in Java

Chapter 6. Dealing with optional data

This chapter covers

• The null reference, or “the billion-dollar mistake”
• Alternatives to null references
• Developing an Option data type for optional data
• Applying functions to optional values
• Composing optional values
• Option use cases

Representing optional data in computer programs has always been a problem. The concept of optional data is very simple in everyday life. Representing the absence of something when this something is contained in a container is easy—whatever it is, it can be represented by an empty container. An absence of apples can be represented by an empty apple basket. The absence of gasoline in a car can be visualized as an empty gas tank.

Representing the absence of data in computer ...