Default Methods on Functional Interfaces

By definition, all functional interfaces have a single abstract method. This doesn’t mean that they have only one method, though. Several of the common functional interfaces provide a number of helpful default methods.
Suppose that we have these two Predicates:

Predicate<String> egg = s -> s.contains("egg");
Predicate<String> brown = s -> s.contains("brown");

Now we want a Predicate for brown eggs and another for all other colors of eggs:

Predicate<String> brownEggs = egg.and(brown);
Predicate<String> otherEggs = egg.and(brown.negate());

Neat! Now we are reusing the logic in the original Predicates to build two new ones. It’s shorter and clearer what the relationship is between the Predicates.