Print names of male members

import java.time.LocalDate;

import java.time.chrono.IsoChronology;

import java.util.ArrayList;

import java.util.List;

import java.util.function.IntConsumer;

public class Main

 public static void main(String[] args)

      List roster = createRoster();

                System.out.println("Male members of the collection (bulk data operations):");

      roster

          .stream()

          .filter(e -> e.getGender() == Person.Sex.Male)

          .forEach(e -> System.out.println(e.getName()));

              public static List createRoster()

        List roster = new ArrayList<>();

        roster.add(

            new Person(

            "Fred",

            IsoChronology.Instance.date(1980, 6, 20),

            Person.Sex.Male,"fredexample"));

        roster.add(

            new Person(

            "Jane",

            IsoChronology.Instance.date(1990, 7, 15),

            Person.Sex.Female, "janeexample"));

        roster.add(

            new Person(

            "George",

            IsoChronology.Instance.date(1991, 8, 13),

            Person.Sex.Male, "georgeexample"));

        roster.add(

            new Person(

            "Bob",

            IsoChronology.Instance.date(2000, 9, 12),

            Person.Sex.Male, "bobexample"));

        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);

Update all graduates from Milan to Cambridge

import java.util.Arrays;

import java.util.Comparator;

import java.util.List;

import java.util.stream.Collectors;

public class Main

 public static void main(String...args)

    Student raoul = new Student("Raoul", "Cambridge");

    Student mario = new Student("Mario","Milan");

    Student alan = new Student("Alan","Cambridge");

    Student brian = new Student("Brian","Cambridge");

    List transactions = Arrays.asList(

        new Graduate(brian, 2011, 300),

        new Graduate(raoul, 2012, 1000),

        new Graduate(raoul, 2011, 400),

        new Graduate(mario, 2012, 710),

        new Graduate(mario, 2012, 700),

        new Graduate(alan, 2012, 950)

);

    transactions.stream()

                .map(Graduate::getTrader)

                .filter(trader -> trader.getCity().equals("Milan"))

                .forEach(trader -> trader.setCity("Cambridge"));

    System.out.println(transactions);

class Student

  private String name;

  private String city;

           public Student(String n, String c)

      this.name = n;

      this.city = c;

  public String getName()

      return this.name;

              public String getCity()

      return this.city;

               public void setCity(String newCity)

      this.city = newCity;

               public String toString()

      return "Student:"+this.name + " in " + this.city;

          class Graduate

            private Student trader;

  private int year;

  private int value;

           public Graduate(Student trader, int year, int value)

      this.trader = trader;

      this.year = year;

      this.value = value;

            public Student getTrader()

      return this.trader;

             public int getYear()

      return this.year;

             public int getValue()

      return this.value;

  public String toString()

      return "{" + this.trader + ", " +

             "year: "+this.year+", " +

             "value:" + this.value +"}";