Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<Person> persons = new ArrayList<Person>();
        persons.add(new Person("Peter", 65, Person.Gender.MALE));
        persons.add(new Person("Kevin", 5, Person.Gender.MALE));
        persons.add(new Person("Mandy", 19, Person.Gender.FEMALE));

        // Method Reference
        Collection<Person> eighteen = list(persons, (Person p) -> p.getAge() >= 18);
        System.out.println(eighteen);

        // Method Reference static
        Collection<Person> malePersons = list(persons, Person::isMale);
        System.out.println(malePersons);

        // Method Reference non static
        Person a = new Person("a", 1, Person.Gender.MALE);
        Collection<Person> femalePersons = list(persons, a::isFemale);
        System.out.println(femalePersons);
    }

    public static Collection<Person> list(Collection<Person> persons, PersonPredicate<Person> predicate) {
        List<Person> matchedPersons = new ArrayList<Person>();
        for (Person p : persons) {
            if (predicate.evaluate(p)) {
                matchedPersons.add(p);
            }
        }
        return matchedPersons;
    }
}

@FunctionalInterface
interface PersonPredicate<T> {
    boolean evaluate(T t);
}

class Person {
    public enum Gender {
        MALE, FEMALE
    }

    private String name;
    private int age;
    private Gender gender;

    public Person(String name, int age, Gender gender) {
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public Gender getGender() {
        return gender;
    }

    public String toString() {
        return getName() + ", " + getAge();
    }

    public static boolean isMale(Person p) {
        return Person.Gender.MALE.equals(p.getGender());
    }

    public boolean isFemale(Person p) {
        return Person.Gender.FEMALE.equals(p.getGender());
    }
}