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![Quick peek at RxJava
Observable<String> letters = Observable.from(new String[] { "a", "b", "c" });
letters.subscribe(letter -> System.out.println("Got letter: " + letter));](https://image.slidesharecdn.com/functionaluiswithjava8andvaadinjavaone2014-141001145029-phpapp01/85/Functional-UIs-with-Java-8-and-Vaadin-JavaOne2014-40-320.jpg)
![Power of Observables - composition
Observable<String> letters = Observable.from(new String[] { "a", “b", "c" });
Observable<Integer> numbers = Observable.from(new Integer[] { 1, 2, 3 });
Observable<String> pairs = Observable.combineLatest(letters, numbers, (l, n) -> {
return "" + l + " -> " + n;
});
!
pairs.subscribe(pair -> System.out.println("Got pair: " + pair));](https://image.slidesharecdn.com/functionaluiswithjava8andvaadinjavaone2014-141001145029-phpapp01/85/Functional-UIs-with-Java-8-and-Vaadin-JavaOne2014-41-320.jpg)
![Quick peek at RxJava
Observable<String> letters = Observable.from(new String[] { "a", "b", "c" });
letters.subscribe(letter -> System.out.println("Got letter: " + letter));](https://image.slidesharecdn.com/functionaluiswithjava8andvaadinjavaone2014-141001145029-phpapp01/75/Functional-UIs-with-Java-8-and-Vaadin-JavaOne2014-40-2048.jpg)
![Power of Observables - composition
Observable<String> letters = Observable.from(new String[] { "a", “b", "c" });
Observable<Integer> numbers = Observable.from(new Integer[] { 1, 2, 3 });
Observable<String> pairs = Observable.combineLatest(letters, numbers, (l, n) -> {
return "" + l + " -> " + n;
});
!
pairs.subscribe(pair -> System.out.println("Got pair: " + pair));](https://image.slidesharecdn.com/functionaluiswithjava8andvaadinjavaone2014-141001145029-phpapp01/75/Functional-UIs-with-Java-8-and-Vaadin-JavaOne2014-41-2048.jpg)
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Similar to Functional UIs with Java 8 and Vaadin JavaOne2014
Functional UIs with Java 8 and Vaadin JavaOne2014
- 1. Functional Vaadin 7 Henri Muurimaa, SVP of Engineering henri@vaadin.com @henrimuurimaa
- 3. Mission Why dowe exist Make building amazing web applications easy
- 4. Vaadin X BuildUIs with components
- 5.
- 6. Web application layers Backend Web server Communication JavaScript JS required required required required Vaadin required required optional optional
- 7. Web application layers Backend Web server Communication JavaScript JS required required required required Vaadin required required optional optional 1 layer vs 3 layers Less code Less bugs Faster time-to-market
- 8. But can it scale?
- 9. Test results 20,622AJAX requests / minute before exceeding 1% rejected connections MPAA reports 1,4 billion movie tickets sold in 2009. ! ~2,700 tickets / minute. 5,496 tickets / minute ~11,000 concurrent users On a single Amazon EC2 Large instance www.vaadin.com/blog/-/blogs/vaadin-scalability-study-quicktickets
- 10. very active there > 100.000 developers from > 10.000 cities > 450 add-ons in the marketplace Other Asia 4 % 20 % Americas 22 % Europe 54 % Open Source community Apache-licensed
- 11.
- 12.
- 13. What is Functional Programming?
- 14. A style ofprogramming that expresses computation as the evaluation of mathematical functions
- 15. Recursion Lazy evaluation Lambda expressions Pattern matching Type theory Monads Referential transparency Currying Entscheidungsproblem Tuples
- 16. Something practical? Sideeffects? State? Denied Denied
- 17.
- 19. What’s in itfor me? A new way of thinking A new way of programming Write tight, robust and scalable code
- 20. What’s hot inJava 8
- 21.
- 22. New Java 8Date API in action public int monthAge() { return (new Date().getYear() - date.getYear()) * 12 + (new Date().getMonth() - date.getMonth()); } // Java 8 version with the new Date API public int monthAge() { return (int) Period.between(date, LocalDate.now()).toTotalMonths(); }
- 23.
- 24. Anonymous functions Runnabler = () -> System.out.println("hello lambda!”); Comparator<Integer> cmp1 = (x, y) -> (x < y) ? -1 : ((x > y) ? 1 : 0); Comparator<Integer> cmp2 = (x, y) -> { return (x < y) ? -1 : ((x > y) ? 1 : 0); // Need return if not one liner }; // Anonymous onsite functions button.addClickListener(event -> System.out.println("Button clicked!"));
- 25. Workout Tracker example editor.clear.addClickListener(new Button.ClickListener() { @Override public void buttonClick(ClickEvent event) { editor.clearValues(); updateRating(); } }); // Java 8 version with a lambda editor.clear.addClickListener(event -> { editor.clearValues(); updateRating(); });
- 26. Method references withthe :: notation ! private void eventHandler(Button.ClickEvent event) { // do something about the button click } button.addClickListener(this::eventHandler); // If the handler method is static button.addClickListener(MyClass::eventHandler);
- 27. Workout Tracker example !editor.activity.addValueChangeListener(new Property.ValueChangeListener() { @Override public void valueChange(ValueChangeEvent event) { updateRating(); } }); editor.date.addValueChangeListener(this::updateRating);
- 28.
- 29. Stream != Collection Create from a Collection or an Iterable Composable to new Streams with higher order functions As lazy as possible
- 30. Input validation privateboolean areInputsValid() { Component component = null; for (Iterator<Component> iter = editor.iterator(); iter.hasNext(); iter.next()) { if (fieldNotValidating(component)) return false; } return true; } // Java 8 version with anyMatch and a method reference private boolean areInputsValid() { return !StreamSupport.stream(editor.spliterator(), true) .anyMatch(this::fieldNotValidating); }
- 31. From rating tostars StringBuilder stars = new StringBuilder("New Workout: "); for (int i = 0; i < rating; ++i) { stars.append(FontAwesome.STAR.getHtml()); } editor.title.setValue("New Workout: “ + stars); String stars = IntStream.range(0, rating) .mapToObj(r -> FontAwesome.STAR.getHtml()) .collect(Collectors.joining("")); editor.title.setValue("New Workout: " + stars);
- 32.
- 33. A function that takes one or more functions as input
- 34. Map Returns anew stream by applying the given function to all elements of this stream. ! Filter Returns a new stream consisting of the elements of this stream that match the given predicate. SQL analogue: SELECT SQL analogue: WHERE
- 35. Workout Tracker Example private List<Workout> findByAge(int maxMonths) { List<Workout> result = new ArrayList<>(); for (Workout w : workouts) { ! ! ! if (w.monthAge() < maxMonths) { result.add(w); } } Collections.sort(result, new Comparator<Workout>() { @Override public int compare(Workout o1, Workout o2) { return o2.monthAge() - o1.monthAge(); } }); ! return result; } private Stream<Workout> findByAge(int maxMonths) { return workouts.stream() ! ! ! .filter(w -> w.monthAge() < maxMonths) .sorted(Comparator.comparing(Workout::monthAge) .reversed()); }
- 36. What is Functional Reactive Programming?
- 37.
- 38.
- 39.
- 40. Quick peek atRxJava Observable<String> letters = Observable.from(new String[] { "a", "b", "c" }); letters.subscribe(letter -> System.out.println("Got letter: " + letter));
- 41. Power of Observables- composition Observable<String> letters = Observable.from(new String[] { "a", “b", "c" }); Observable<Integer> numbers = Observable.from(new Integer[] { 1, 2, 3 }); Observable<String> pairs = Observable.combineLatest(letters, numbers, (l, n) -> { return "" + l + " -> " + n; }); ! pairs.subscribe(pair -> System.out.println("Got pair: " + pair));
- 42.
- 43. Rating to stars,reactive style! Observable<String> activities = RxVaadin.valuesWithDefault(editor.activity, null); Observable<String> durations = RxVaadin.valuesWithDefault(editor.duration, ""); Observable<Date> dates = RxVaadin.valuesWithDefault(editor.date, editor.date.getValue()); Observable<String> calories = RxVaadin.valuesWithDefault(editor.calories, ""); Observable<String> avgHRs = RxVaadin.valuesWithDefault(editor.avgHR, ""); Observable<String> maxHRs = RxVaadin.valuesWithDefault(editor.maxHR, ""); Observable<String> comments = RxVaadin.valuesWithDefault(editor.comment, "");
- 44. Composing the ratingObservable Observable<Integer> ratings = WorkoutRatingLogic.ratings(activities, durations, dates, calories, avgHRs, maxHRs, comments); Observable<String> ratingStrings = ratings.map(rating -> { if (rating == null) { return "New Workout”; // No stars if required fields not ok } else { return IntStream.range(0, rating) .mapToObj(i -> FontAwesome.STAR.getHtml()) .collect(Collectors.joining("", "New Workout: ", "")); } });
- 45. Last step: updatethe UI // Have the label update its value whenever the Observable // emits a value RxVaadin.follow(editor.title, ratingStrings); // Disable or enable the add button based on if the rating // calculation was successful or not ratings.subscribe(rating -> editor.add.setEnabled(rating != null));
- 46.
- 47. The functional additionsin Java 8 rock Observables allow us avoid the “callback hell” with events Vaadin works brilliantly with both
- 48. Thank You! ! github.com/hezamu @henrimuurimaa henri@vaadin.com
- 49. ! Join usfor a chat and drinks at the Vaadin Meetup ! Hotel Serrano Right now!