Functional Programming in Java

Decorating Using Lambda Expressions

So far we’ve avoided creating implementation classes to support the delegate interfaces. We needed simple implementations for these interfaces, so that worked out fairly well. Let’s increase our demands on these implementations, ask them to interact with multiple delegates, and see how lambda expressions handle that.

Delegation is great, but we can take it further if we can chain delegates to add behavior. We can then create discrete flavors of behavior and sprinkle them onto the classes, like the mix-ins at the ice-cream shop.

The decorator pattern is powerful, but programmers often hesitate to use it due to the burdensome hierarchy of classes and interfaces—like FilterInputStream and FilterOutputStream ...