Retro Gaming with Lambdas

2. Retro Gaming with Lambdas Alexander BelokrylovPrograms and Community manager @gigabel

3. http://www.behance.net/gallery/Barbie/2143713

4. Common case for(Orange o:orangebox){ if(o.getColor()==GREEN) o.setColor(ORANGE); } http://www.californiaoranges.com/40lb-box-bushel-organic-valencia-oranges.html

5. http://www.behance.net/gallery/Barbie/2143713

6. JDK 8 Lambdas? In my Java?

7. Common case with Lambdas orangebox.forEach(o → { if(o.getColor()==GREEN) o.setColor(ORANGE); }) http://www.californiaoranges.com/40lb-box-bushel-organic-valencia-oranges.html

8. Collection.forEach()

9. Default methods interface Collection<T>{ ... defaultvoidforEach(Block<T> action){ for(T t:this) action.apply(t); } }

10. Up to you

11. Small change – big impact

12. Mary had a little Lambda Mary had a little lambda Whose fleece was white and snow And everywhere that Mary went Lambda was sure to go! https://github.com/steveonjava/MaryHadALittleLambda

13. Iterating with Lambdas

14. Iterating with Lambdas Stream generation Group cells =newGroup(IntStream .range(0, HORIZONTAL_CELLS) .mapToObj(i-> IntStream .range(0, VERTICAL_CELLS) .mapToObj(j ->{ // Logic goes here returnrect;})) .flatMap(s -> s) .toArray(Rectangle[]::new));

15. Iterating with Lambdas

16. Iterating with Lambdas Stream iterate() s.getAnimals().addAll(Stream .iterate(tail, lamb ->newSpriteView.Lamb(lamb)) .substream(1,8) .collect(Collectors.toList()));

17. Iterating with Lambdas • Collection streaming • Collection.stream(); • Set of objects • Stream.of(bananas, oranges, apples); • Numeric range • IntStream.range(0, 100); • Itaratively • Stream.iterate(tail, lamb -> new Lamb(lamb));

18. Filtering Stream with Lambdas

19. Filtering Stream with Lambdas publicvoidvisit(Shepherd s){ s.getAnimals().stream().filter(a ->a.getNumber()%4==1) .forEach(a ->a.setColor(null)); s.getAnimals().stream().filter(a ->a.getNumber()%4==2) .forEach(a ->a.setColor(Color.YELLOW)); s.getAnimals().stream().filter(a ->a.getNumber()%4==3) .forEach(a ->a.setColor(Color.CYAN)); s.getAnimals().stream().filter(a ->a.getNumber()%4==0) .forEach(a ->a.setColor(Color.GREEN)); }

20. Filtering Stream with Lambdas Predicate publicstatic Predicate<SpriteView>checkIfLambIs(Integer number){ return lamb ->lamb.getNumber()%4== number;} @Override publicvoidvisit(Shepherd s){ s.getAnimals().stream().filter(checkIfLambIs(1)) .forEach(a ->a.setColor(null)); s.getAnimals().stream().filter(checkIfLambIs(2)) .forEach(a ->a.setColor(Color.YELLOW)); s.getAnimals().stream().filter(checkIfLambIs(3)) .forEach(a ->a.setColor(Color.CYAN)); s.getAnimals().stream().filter(checkIfLambIs(0)) .forEach(a ->a.setColor(Color.GREEN));}

21. Filtering Collections with Lambdas

22. Filtering Collection with Lambdas Function static Function<Color, Predicate<SpriteView>>checkIfLambColorIs = color ->{Predicate<SpriteView>checkIfColorIs = lamb ->lamb.getColor()== color; returncheckIfColorIs;}; @Override publicvoidvisit(Shepherd s){ mealsServed.set(mealsServed.get()+ s.getAnimals() .filtered(checkIfLambColorIs.apply(todayEatableColor)) .size()); s.getAnimals() .removeIf(checkIfLambColorIs.apply(todayEatableColor));}

23. Filtering Collectionswith Lambdas Function static Function<Color, Predicate<SpriteView>>checkIfLambColorIs = color ->{Predicate<SpriteView>checkIfColorIs = lamb ->lamb.getColor()== color; returncheckIfColorIs;}; @Override publicvoidvisit(Shepherd s){ mealsServed.set(mealsServed.get()+ s.getAnimals() .filtered(checkIfLambColorIs.apply(todayEatableColor)) .size()); s.getAnimals() .removeIf(checkIfLambColorIs.apply(todayEatableColor));}

24. Filtering Collectionswith Lambdas Function @Override publicvoidvisit(Shepherd s){ Function<Color, Predicate<SpriteView>>checkIfLambColorIs= color -> lamb ->lamb.getColor()== color; mealsServed.set(mealsServed.get()+ s.getAnimals() .filtered(checkIfLambColorIs.apply(todayEatableColor)) .size()); s.getAnimals() .removeIf(checkIfLambColorIs.apply(todayEatableColor))}

25. Filtering Collection with Lambdas • Removes all elements that match the predicate • Collection.removeIf(); • Filtering and replacement • Collection.replaceAll(); • Returns collection filtered by predicate • ObservableCollection.filtered();

26. Mapping Stream with Lambda

27. Mapping Stream with Lambda Single Map @Override publicvoidvisit(Shepherd s){ // single map: s.getAnimals() .setAll(s.getAnimals() .stream() .map(sv->new Eggs(sv.getFollowing())) .collect(Collectors.toList())); }

28. Mapping Stream with Lambda Double Map @Override publicvoidvisit(Shepherd s){ // double map: s.getAnimals() .setAll(s.getAnimals() .stream() .map(SpriteView::getFollowing) .map(Eggs::new) .collect(Collectors.toList())); }

29. Mary had a little Lambda • OpenSource project to demonstrate Lambda features • Visual representation of strams, filters, maps • Created by Stephen Chin, @steveonjava https://github.com/steveonjava/MaryHadALittleLambda

30. Reading

31. Reading

32. The preceding is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract.It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.