Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.time.LocalDate;
import java.time.chrono.IsoChronology;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.IntConsumer;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        List<Person> roster = createRoster();

        System.out.println("Total age by gender:");
        Map<Person.Sex, Integer> totalAgeByGender = roster.stream().collect(
                Collectors.groupingBy(Person::getGender, Collectors.reducing(0, Person::getAge, Integer::sum)));

        List<Map.Entry<Person.Sex, Integer>> totalAgeByGenderList = new ArrayList<>(totalAgeByGender.entrySet());

        totalAgeByGenderList.stream()
                .forEach(e -> System.out.println("Gender: " + e.getKey() + ", Total Age: " + e.getValue()));

    }

    public static List<Person> createRoster() {

        List<Person> roster = new ArrayList<>();
        roster.add(
                new Person("Fred", IsoChronology.INSTANCE.date(1980, 6, 20), Person.Sex.MALE, "fred@example.com"));
        roster.add(new Person("Jane", IsoChronology.INSTANCE.date(1990, 7, 15), Person.Sex.FEMALE,
                "jane@example.com"));
        roster.add(new Person("George", IsoChronology.INSTANCE.date(1991, 8, 13), Person.Sex.MALE,
                "george@example.com"));
        roster.add(new Person("Bob", IsoChronology.INSTANCE.date(2000, 9, 12), Person.Sex.MALE, "bob@example.com"));

        return roster;
    }
}

class Averager implements IntConsumer {
    private int total = 0;
    private int count = 0;

    public double average() {
        return count > 0 ? ((double) total) / count : 0;
    }

    public void accept(int i) {
        total += i;
        count++;
    }

    public void combine(Averager other) {
        total += other.total;
        count += other.count;
    }
}

class Person {

    public enum Sex {
        MALE, FEMALE
    }

    String name;
    LocalDate birthday;
    Sex gender;
    String emailAddress;

    Person(String nameArg, LocalDate birthdayArg, Sex genderArg, String emailArg) {
        name = nameArg;
        birthday = birthdayArg;
        gender = genderArg;
        emailAddress = emailArg;
    }

    public int getAge() {
        return birthday.until(IsoChronology.INSTANCE.dateNow()).getYears();
    }

    public void printPerson() {
        System.out.println(name + ", " + this.getAge());
    }

    public Sex getGender() {
        return gender;
    }

    public String getName() {
        return name;
    }

    public String getEmailAddress() {
        return emailAddress;
    }

    public LocalDate getBirthday() {
        return birthday;
    }

    public static int compareByAge(Person a, Person b) {
        return a.birthday.compareTo(b.birthday);
    }

}

/*
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 *
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 * modification, are permitted provided that the following conditions
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 *     notice, this list of conditions and the following disclaimer.
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 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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