Refactoring, testing, and debugging - Java 8 in Action: Lambdas, Streams, and Functional-Style Programming - page 251

8.5. Summary
Following are the key concepts you should take away from this chapter:
 Lambda expressions can make your code more readable and flexible.
 Consider converting anonymous classes to lambda expressions, but be wary of subtle semantic
differences such as the meaning of the keyword this and shadowing of variables.
 Method references can make your code more readable compared to lambda expressions.
 Consider converting iterative collection processing to use the Streams API.
 Lambda expressions can help remove boilerplate code associated with several object-oriented design
patterns such as strategy, template method, observer, chain of responsibility, and factory.
 Lambda expressions can be unit tested, but in general you should focus on testing the behavior of the
methods where the lambda expressions appear.
 Consider extracting complex lambda expressions into regular methods.
 Lambda expressions can make stack traces less readable.
 The peek method of a stream is useful to log intermediate values as they flow past at certain points in
a stream pipeline.