ReductionExample.java

package com.kiroule.ocpupgradejava8.topic5_2;

import java.util.Arrays;
import java.util.List;

/**
 * @author Igor Baiborodine
 */
public class ReductionExample {

  public static void main(String... args) {

    List<FuturamaCharacter> characters = Arrays.asList(
        new FuturamaCharacter("Bender", "Rodriguez", 5),
        new FuturamaCharacter("Philip", "Fry", 126),
        new FuturamaCharacter("Turanga", "Leela", 22));

    System.out.println("Futurama characters:");
    characters.forEach(c -> System.out.println(c));

    int sumAge = characters
        .stream()
        .parallel()
        .mapToInt(FuturamaCharacter::getAge)
        .sum();
    System.out.println("\nSum of ages: " + sumAge);

    int sumAgeReduce = characters
        .stream()
        .parallel()
        .map(FuturamaCharacter::getAge)
        .reduce(0, (a, b) -> a + b);
    System.out.println("\nSum of ages with reduce: " + sumAgeReduce);
  }
}

class FuturamaCharacter {

  private String firstName;
  private String lastName;
  private int age = 0;

  public FuturamaCharacter(String firstName, String lastName, int age) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.age = age;
  }

  public int getAge() {
    return age;
  }

  @Override
  public String toString() {
    return firstName + " " + lastName + " [" + age + "]";
  }
}