Java 8 Lambdas

Chapter 7. Testing, Debugging, and Refactoring

The rising popularity of techniques such as refactoring, test-driven development (TDD), and continuous integration (CI) mean that if we’re going to use lambda expressions in our day-to-day programming, we need to understand how to test code using them and written with them.

A wealth of material has been written on how to test and debug computer programs, and this chapter isn’t going to revisit all that material. If you’re interested in learning how to do TDD properly, I highly recommend the books Test-Driven Development by Kent Beck and Growing Object-Oriented Software, Guided by Tests by Steve Freeman and Nat Pryce (both from Addison-Wesley).

I am going to cover techniques specific to using lambda expressions in your code, and when you might not want to (directly) use lambda expressions at all. I’ll also talk about some appropriate techniques for debugging programs that heavily use lambda expressions and streams.

We’re first going to look at some examples of how to refactor an existing code base into using lambda expressions. I’ve talked a bit already about how to do local refactoring operations, such as replacing a for loop with a stream operation. Here we’ll take a more in-depth look at how non-collection code can be improved.

Lambda Refactoring Candidates

The process of refactoring code to take advantage of lambdas has been given the snazzy name point lambdafication (pronounced lambda-fi-cation, practitioners of this process being “lamb-di-fiers” ...