Predicates  🕵

Predicates is a set of helper methods which facilitate with writing clean functional code. It's designed to replace common lambda's, using logical naming.

against

Filter against a property of an object.

This may be helpfull when going through a stream, where you don't want to dig into the object using a lambda.

Predicates.against(Person::getName, "Johnny"); // Predicate<Person>

all

Combine multiple predicates into one, where each provided Predicate should evaluate to true.

Predicates.all(predicate1, predicate2); // Predicate<T>

any

Combine multiple predicates into one, where any of the provided Predicate should evaluate to true.

Predicates.any(predicate1, predicate2); // Predicate<T>

always(boolean)

No matter what, this Predicate will always return the given boolean value.

Predicates.always(true); // Predicate<?>

alwaysTrue

No matter which value provided, this Predicate will always return true.

Predicates.alwaysTrue(); // Predicate<?>

alwaysFalse

No matter which value provided, this Predicate will always return false.

Predicates.alwaysFalse(); // Predicate<?>

cached

Cache the outcome (null-safe) of a Predicate against the distinct values it's provided. Each consecutive test for a value which has already been encountered, will fetch the result from a cache rather than evaluating the Predicate again.

This can be helpful when the Predicate houses an expensive operation, which does not change within the lifespan of the Predicate.

Predicates.cached(Files::exists); // Predicate<Path>

safe

Evaluates the outcome of a Boolean-method as a null-safe predicate. If the Boolean-method returns null, then the Predicate will result to false.

Predicates.safe(Method::getBoolean); // Predicate<Method>