Java 8 lambdas multiple filter calls

Question

When using filter(Predicate<? super T> predicate) calls in Java 8 lambda expressions, I'm in two minds about whether to put all the Predicate logic in one call, or to chain filter(Predicate<? super T> predicate) calls to aid readability where appropriate.

I presume that chaining filter(Predicate<? super T> predicate) calls will be inexpensive since they have not yet met a terminator, so would err on the side of readability but I'm not confident enough in my knowledge of the Streams API to fully understand what the trade-offs are.

With the aid of the following example (consider too more complex predicates), which implementation is superior: List<Person> usingOneFilter or List<Person> usingTwoFilters?

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class SEExample {

    private static class Person {
        private final int age;
        private final int heightInCm;

        public Person(int age, int heightInCm) {
            this.age = age;
            this.heightInCm = heightInCm;
        }

        public int getAge() {
            return age;
        }

        public int getHeight() {
            return heightInCm;
        }
    }

    public static void main(String[] args) {
        List<Person> people = Arrays.asList(
                new Person(14, 140), 
                new Person(15, 140), 
                new Person(16, 150), 
                new Person(17, 120));
        List<Person> usingOneFilter = people
                .stream()
                .filter(p -> p.getAge() >= 16 && p.getHeight() >= 130)
                .collect(Collectors.toList());
        List<Person> usingTwoFilters = people
                .stream()
                .filter(p -> p.getAge() >= 16)
                .filter(p -> p.getHeight() >= 130)
                .collect(Collectors.toList());
    }

}

Answer 1

In such a small example I think readability isn't really compromised, but I still prefer using separate filter methods. Certainly if it's any more complex.

This is indeed not very expensive. There's no reason to "optimize" it unless you have a performance issue and profiling reveals that this is the bottleneck. But that's extremely unlikely.