Predicate simple example

package my.home;

import java.util.Arrays;
import java.util.function.Predicate;

public class Main {

    public static void main(String[] args) {
        Predicate s = (q) -> q.length() > 3;
        System.out.println("len>3 = " + s.test("12345"));
        System.out.println("len<3 = " + s.test("45"));

        java.util.List a1 = Arrays.asList(7, 6, 5, 4, 3, 2, 1);

        Arrays.asList(
                new Main().sum(a1, (q) -> q > 5),
                new Main().sum(a1, (q) -> q % 2 == 0),
                new Main().sum(a1, (q) -> q < 4),
                new Main().sum(a1, (q) -> true)
        ).forEach(System.out::println);
    }

    private Integer sum(java.util.List integerList, Predicate predicate) {
        Integer sum = 0;
        for (Integer intVal : integerList) {
            if (predicate.test(intVal)) {
                sum += intVal;
            }
        }
        return sum;
    }
}

Output:
len>3 = true
len<3 = false
13
12
6
28