Java 8 Parallel Stream Basic Usage & Perf. Test

	public class Main {
	public static void main (String[] args) {
	Stomach stomach = new Stomach ();
	long startTime = System.currentTimeMillis ();
	for (int i = 0; i < 10000; i++) {
	stomach.accept (new Salad ());
	stomach.accept (new Burger ());
	}
	long normalDigestionDuration = System.currentTimeMillis () - startTime;
	//------------------------------------------------------------------------------------------
	Consumer<Food> c = (Food food)-> {
	System.out.println ("Eating the " +food);
	};
	List<Food> foods = new ArrayList<> ();
	for (int i = 0; i < 10000; i++) {
	stomach.accept (new Salad ());
	stomach.accept (new Burger ());
	}
	startTime = System.currentTimeMillis ();
	foods.parallelStream ().map (food->{consumeFood (food,c);return food;}).count ();
	long paralelStreamDigestDuration = System.currentTimeMillis () - startTime;
	//------------------------------------------------------------------------------------------
	System.out.println ("Digestion duration is :" + normalDigestionDuration);// ~120 ms
	System.out.println ("Digestion with parallel stream = " + paralelStreamDigestDuration);// ~7 ms...so fast huh ?
	}
	public static void consumeFood (Food food, Consumer<Food> consumer){
	consumer.accept (food);
	}
	}
	Outputs::
	Digestion duration is :120
	Digestion with parallel stream = 7

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Java 8 Consumer SAM sample

	public abstract class Food {
	public abstract void giveEnergy () ;
	}
	public class Burger extends Food {
	@Override
	public void giveEnergy () {
	System.out.println ("Burger gives high energy");
	}
	}
	public class Salad extends Food {
	@Override
	public void giveEnergy () {
	System.out.println ("Salad does not give energy");
	}
	}
	package com.company.samples.way6;
	import java.util.function.Consumer;
	public class Stomach<T extends Food> implements Consumer<T> {
	@Override
	public void accept (T t) {
	t.giveEnergy ();
	}
	}
	package com.company.samples.way6;
	public class Main {
	public static void main (String[] args) {
	Stomach stomach = new Stomach ();
	stomach.accept (new Salad ());
	stomach.accept (new Burger ());
	}
	}
	Outputs:::
	Salad does not give energy
	Burger gives high energy

view raw ConsumerSample.java hosted with ❤ by GitHub

Java 8 stream samples not much but easily reachable

	package com.company.samples.way4;
	import java.util.*;
	import java.util.stream.Collectors;
	/**
	* Created by serkan on 28.11.2016.
	*/
	public class Main {
	public static void main (String[] args) {
	List<Person> roster = new ArrayList<Person> ();
	roster.add (new Person ("John", 23, Gender.Male));
	roster.add (new Person ("wayne", 37, Gender.Male));
	roster.add (new Person ("Angelina", 23, Gender.Femal));
	roster.add (new Person ("Jolie", 12, Gender.Femal));
	roster.add (new Person ("Wolverine", 500, Gender.Male));
	roster.add (new Person ("Xavier", 70, Gender.Male));
	roster.add (new Person ("Aişe", 6, Gender.Femal));
	roster.add (new Person ("Aişe", 6, Gender.Femal));
	Map<Gender, List<Person>> byGender = roster.parallelStream ().collect (Collectors.groupingByConcurrent (Person::getGender));
	System.out.println ("byGender = " + byGender);//this is so cool huh ?
	Double averageAge = roster.parallelStream ().collect (Collectors.averagingInt (Person::getAge));
	System.out.println ("averageAge = " + averageAge);
	OptionalDouble anotherAverageAge = roster.parallelStream ().mapToInt (p -> p.getAge ()).average ();
	System.out.println ("anotherAverageAge = " + anotherAverageAge);
	List<Person> femalesOnly = roster.parallelStream ().filter (p -> p.getGender () == Gender.Femal).collect (Collectors.toList ());
	System.out.println ("femalesOnly = " + femalesOnly);
	List<Person> distinct = roster.parallelStream ().distinct ().collect (Collectors.toList ());
	System.out.println ("distinct = " + distinct);
	Set<Person> anotherDistinct = roster.parallelStream ().collect (Collectors.toSet ());
	System.out.println ("anotherDistinct = " + anotherDistinct);
	int sumOfAges = roster.parallelStream ().mapToInt (Person::getAge).sum ();
	System.out.println ("sumOfAges = " + sumOfAges);
	int anotherSumOfAges = roster.parallelStream ().mapToInt (p-> p.getAge ()).sum ();
	System.out.println ("anotherSumOfAges = " + anotherSumOfAges);
	long justAnotherSumOfAges = roster.parallelStream ().collect (Collectors.summarizingInt (Person::getAge)).getSum ();
	System.out.println ("justAnotherSumOfAges = " + justAnotherSumOfAges);
	final Comparator<Person> comp = (p1, p2) -> Integer.compare( p1.getAge(), p2.getAge());
	Person oldest = roster.stream().max(comp).get();
	System.out.println ("oldest = " + oldest);
	Person youngest = roster.stream().min((p1, p2) -> Integer.compare(p1.getAge(), p2.getAge())).get();
	System.out.println ("youngest = " + youngest);
	String lexicalLatests = roster.parallelStream ().max ((p1, p2) -> p1.getName ().compareTo (p2.getName ())).get ().getName ();
	System.out.println ("lexicalLatests = " + lexicalLatests);
	}
	}
	byGender = {Male=[Person{name='Xavier', age=70, gender=Male}, Person{name='Wolverine', age=500, gender=Male}, Person{name='wayne', age=37, gender=Male}, Person{name='John', age=23, gender=Male}], Femal=[Person{name='Aişe', age=6, gender=Femal}, Person{name='Aişe', age=6, gender=Femal}, Person{name='Angelina', age=23, gender=Femal}, Person{name='Jolie', age=12, gender=Femal}]}
	averageAge = 84.625
	anotherAverageAge = OptionalDouble[84.625]
	femalesOnly = [Person{name='Angelina', age=23, gender=Femal}, Person{name='Jolie', age=12, gender=Femal}, Person{name='Aişe', age=6, gender=Femal}, Person{name='Aişe', age=6, gender=Femal}]
	distinct = [Person{name='John', age=23, gender=Male}, Person{name='wayne', age=37, gender=Male}, Person{name='Angelina', age=23, gender=Femal}, Person{name='Jolie', age=12, gender=Femal}, Person{name='Wolverine', age=500, gender=Male}, Person{name='Xavier', age=70, gender=Male}, Person{name='Aişe', age=6, gender=Femal}]
	anotherDistinct = [Person{name='John', age=23, gender=Male}, Person{name='wayne', age=37, gender=Male}, Person{name='Wolverine', age=500, gender=Male}, Person{name='Xavier', age=70, gender=Male}, Person{name='Angelina', age=23, gender=Femal}, Person{name='Jolie', age=12, gender=Femal}, Person{name='Aişe', age=6, gender=Femal}]
	sumOfAges = 677
	anotherSumOfAges = 677
	justAnotherSumOfAges = 677
	oldest = Person{name='Wolverine', age=500, gender=Male}
	youngest = Person{name='Aişe', age=6, gender=Femal}
	lexicalLatests = wayne

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