Timing is Everything

Transcript

1. Timing is Everything Katheryn Shi @Katfishi
3. 141 partners worldwide 1,825 courses 3 million downloads
4. Timer ScheduledThreadPoolExecutor Handler AlarmManager
5. Timer
6. Timer timer = new Timer(); TimerTask task = new TimerTask() { @Override public void run() { // task here } }
7. timer.schedule(task, new Date()); timer.schedule(task, TIME_DELAY);
8. timer.schedule( task, new Date(), PERIOD); timer.schedule( task, TIME_DELAY, PERIOD);
9. timer.scheduleAtFixedRate( task, new Date(), PERIOD); timer.scheduleAtFixedRate( task, TIME_DELAY, PERIOD);
10. Coffee Break
11. fixed-period fixed-rate 10 am 11 am 12 pm 1 pm 2 pm
12. task.cancel(); timer.cancel(); timer.purge();
13. Reusable?
14. Which Thread?
15. TimerTask lengthy = new TimerTask() { @Override public void run() { lengthyOperation(); } }
16. TimerTask task = new TimerTask() { @Override public void run() { flipBackgroundColor(); } }
17. timer.schedule(task, 1000); timer.schedule(lengthy, 0);
19. + Simple – Memory leaks – Single thread – Not reusable – Little control
22. ScheduledThreadPoolExecutor / ScheduledExecutorService
23. ScheduledExecutorService service = Executors .newSingleThreadScheduledExecutor();
24. ScheduledExecutorService service = Executors.newScheduledThreadPool(2);
25. Runnable r = new Runnable() { @Override public void run() { // task here } }
26. ScheduledFuture future = service.schedule(r, 10, TimeUnit.SECONDS); future.cancel(true);
27. TimeUnit.DAYS TimeUnit.HOURS TimeUnit.MINUTES TimeUnit.SECONDS TimeUnit.MILLISECONDS TimeUnit.MICROSECONDS TimeUnit.NANOSECONDS
28. scheduleAtFixedRate(Runnable, long, long, TimeUnit) scheduleWithFixedDelay(Runnable, long, long, TimeUnit)
29. scheduleAtFixedRate scheduleWithFixedDelay 10 am 11 am 12 pm 1 pm 2 pm
30. service.shutdown(); List<Runnable> unexecuted = service.shutdownNow();
31. Reusable?
32. Which Thread?
34. + Multiple threads + More control + Reusable – Complicated
36. Handler
37. Message Queue Handler Handler Looper M M M
38. Message Queue Handler Handler Looper M M M
39. Message Queue Handler Handler Looper M M M
40. Message Queue Handler Handler Looper M M M
41. Message Queue Handler Handler Looper M M M
42. Handler handler = new Handler(); Runnable r = new Runnable() { @Override public void run() { // task here } }
43. handler.postDelayed(r, TIME_DELAY); handler.postAtTime(r, UPTIME_MILLIS);
44. Runnable r = new Runnable() { @Override public void run() { // task here handler.postDelayed(this, TIME_DELAY); } }
45. handler.removeCallbacks(r);
46. Reusable?
47. Which Thread?
48. + Android + More control + Reusable – Long operations
49. AlarmManager
50. AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
51. public static class AlarmReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { // task here } }
52. Intent i = new Intent( MainActivity.this, AlarmReceiver.class); PendingIntent pi = PendingIntent .getBroadcast( MainActivity.this, REQUEST_CODE, i, FLAGS);
53. am.set(AlarmManager.RTC_WAKEUP, TRIGGER_TIME, pi); am.setRepeating( AlarmManager.RTC_WAKEUP, TRIGGER_TIME, INTERVAL, pi);
54. AlarmManager.RTC_WAKEUP AlarmManager.RTC AlarmManager.ELAPSED_REALTIME_WAKEUP AlarmManager.ELAPSED_REALTIME
55. am.cancel(pi);
56. + Sleep control – Complex
57. quick fix Timer more control ScheduledThreadPoolExecutor easy Android Handler wake up AlarmManager
58. @Katfishi github.com/katfishi kshi@ .org