Joda Time

A time manipulation library for Java SDK's Calendar replacement

Transcript

1. Joda Time
9. 9 Content  Joda-Time - introduction  Joda-Time concepts  JDK Calendar. Why we should use Joda-Time?  Specifics and advantages  Integration  Demo
10. 10 Joda-Time Intorduction {0}  Joda-Time provides a Java library for date and time handling  It is an open-source software under ASF2* license  It totally replaces the JDK Date and Calendar classes * http://www.apache.org/licenses/LICENSE-2.0)
11. 11 Joda-Time Introduction {1}  Joda is 100 percent interoperable with the JDK, so you don't need to replace all of your Java code, only the parts that do date/time calculations.  Joda-Time makes time and date values easy to manage, manipulate, and understand. Ease of use, in fact, is Joda's primary design goal
12. 12 Joda concepts ◦Instant ◦Partial ◦Chronology ◦Time zone ◦Immutability
13. 13 Instant Demo
14. 14 Partial LocalDate -> DateTime formula: Partial + Missing fields (Time zone) = Instant DEMO
15. 15 Chronology  Examples of chronologies supported by Joda are: ISO8601 (default) Gregorian/Julian Gregorian Julian Buddhist (Thai) Coptic Ethiopic Islamic  And by JDK Calendar: Buddhist Japanese Gregorian
16. 16 Chronology coptic = CopticChronology.getInstance(); How to get a Chronology object for the Coptic calendar?
17. 17 Time zones DateTimeZone zone = DateTimeZone.forID("Asia/Tokyo"); Chronology gregorianJuian = GJChronology.getInstance(zone);
18. 18 Interval Interval -> ReadablePeriod (fields)
19. 19 Duration
20. 20 Period
21. 21 Interval, Duration and Period Demo
22. 22 Immutability  Like the java.lang.String. Most (but not all) of the Joda objects are immutable.  So when changing an object new object is returned (it is often forgotten)!  Thread-safety
23. 23 Constructors  Date - a JDK instant  Calendar - a JDK calendar  String - in ISO8601 format  Long - in milliseconds  any Joda-Time datetime class This list is extensible. A little type-safety for extensibility. Takes Object!
24. 24 Integration {0} Hibernate Grails JSP JAXB And more...
25. 25 Integration Grails
26. 26 Integration Hibernate @Column @Type(type="org.joda.time.contrib.hibernate.PersistentLocalDate") private LocalDate myDate;
27. 27 Why should we use Joda-Time instead of JDK Calendar and Date?  January 1, 2000 (00:00h).  No java.util.Date - java.util.Calendar should be used.
28. 28 Let's use java.util.Calendar then... // Remember the date from the previous slide? // 2000.01.01, 00:00 (a.k.a “The Millennium bug”) Calendar calendar = Calendar.getInstance(); calendar.set(2000, Calendar.JANUARY, 1, 0, 0, 0); Using Joda-Time it would look pretty much like this: DateTime dateTime = new DateTime(2000, 1, 1, 0, 0, 0, 0);
29. 29 Adding 90 days to an instant and printing the result, the JDK way Calendar calendar = Calendar.getInstance(); calendar.set(2000, Calendar.JANUARY, 1, 0, 0, 0); SimpleDateFormat sdf = new SimpleDateFormat("E MM/dd/yyyy HH:mm:ss.SSS"); calendar.add(Calendar.DAY_OF_MONTH, 90); System.out.println(sdf.format(calendar.getTime()));
30. 30 Adding 90 days to an instant and printing the result, using Joda DateTime dateTime = new DateTime(2000, 1, 1, 0, 0, 0, 0); System.out.println( dateTime.plusDays(90) .toString("E MM/dd/yyyy HH:mm:ss.SSS");
31. 31 A bit more complexity? Pseudo code: get_date( last_day_of_week( month_of(January 1, 2000 + 45 days + 1 month))) WHAT?
32. 32 Joda to the rescue DateTime dateTime = new DateTime(2000,1,1,0,0,0,0); System.out.println( dateTime.plusDays(45) .plusMonths(1) .dayOfWeek() .withMaximumValue() .toString("E MM/dd/yyyy HH:mm:ss.SSS"));
33. 33 Formatting and Parsing  Slow in the JDK's SimpleDateFormat  40ms per format/parse  Not thread-safe  Using DateTimeFormatter – 4ms (10 times faster)  Joda-Time .toString() uses DateTimeFormatter Speed Test Demo
34. 34 Daylight saving time The sad story...
41. 41 Encripted message: 27.10.2012, 19:30 plus 24 hours and we attack!
42. 42 I calculated it, we don't have much time
44. 44 Sad but true!
45. 45 Done what I have!?! Never use java.util.Calendar again I will!
46. 46 Joda Time
47. 2012, 10, 27, 19, 30
48. 48 Why did it happen this way? DEMO
49. 49 Conclusions
50. 50 Conclusion on java.util.Calendar Roughly useful and a bit stiff it is. No hydraulics?!?!
51. 51 Conclusion on Joda-Time That more like it is
52. 52 Wake up, we'll finish in a moment!  Joda-Time – very effective tool for manipulating date and time  Date calculation, formatting, parsing and printing  Replaces JDK Calendar and Date
54. 54 Use Joda-Time – save a Jedi !
56. For wathcing I thank you!