Passing code with behavior parameterization - Java 8 in Action: Lambdas, Streams, and Functional-Style Programming - page 32

You can see these criteria as different behaviors for the filter method. What you just did is
related to the strategy design pattern, [ 1 ] which lets you define a family of algorithms, encapsulate
each algorithm (called a strategy), and select an algorithm at run-time. In this case the family of
algorithms is ApplePredicate and the different strategies are AppleHeavyWeightPredicate and
AppleGreenColorPredicate.
1 See http://en.wikipedia.org/wiki/Strategy_pattern .
But how can you make use of the different implementations of ApplePredicate? You need your
filterApples method to accept ApplePredicate objects to test a condition on an Apple. This is
what behavior parameterization means: the ability to tell a method to take multiple behaviors
(or strategies) as parameters and use them internally to accomplish different behaviors.
To achieve this in the running example, you add a parameter to the filterApples method to take
an ApplePredicate object. This has a great software engineering benefit: you can now separate
the logic of iterating the collection inside the filterApples method with the behavior you want to
apply to each element of the collection (in this case a predicate).
2.2.1. Fourth attempt: filtering by abstract criteria
Our modified filter method, which uses an ApplePredicate, looks like this: