import java.security.SecureRandom; import java.util.ArrayList; import java.util.List; public class BooleanFilter { public static void main(String... args) { IntegerFilter rp = new IntegerFilter(); rp.doWork(); } public void doWork() { List randoms = buildList(); randoms.stream().filter(this::isNumberEven).forEach( p -> { System.out.println(String.format("%d is even", p)); }); } private boolean isNumberEven(Integer number) { return number.intValue() % 2 == 0; } private List buildList() { SecureRandom rand = new SecureRandom(); List randoms = new ArrayList<>(); for (int i = 0; i < 5; i++) { randoms.add(rand.nextInt()); } return randoms; } }