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Java Dating - JSR 310 Lightning Talk
- 1. LJC/JCP Committee Java Dating By James Gough Thursday, 14 July 2011
- 2. LJC/JCP ? Who am I? ? What is the LJC/JCP? ? Why get involved? Thursday, 14 July 2011
- 3. Who am I? ? James Gough ? jpgough@gmail.com ? Twitter: goughjam ? Java developer for 8 years, 4 years industry experience ? Work at a large investment bank developing Flex and Java ? Run my own company in spare time developing iOS applications 3 Thursday, 14 July 2011
- 4. LJC/JCP ? LJC recently elected onto the JCP committee ? JCP (Java Community Process) ? The JCP is the mechanism for developing standard technical speci?cations for the Java technology ? Interested? Ben Evans @kittylst on twitter, or ?nd me at the bar on Tuesday 4 Thursday, 14 July 2011
- 5. Why get involved? ? Chance to have a say ? Discover more about Java and the inner workings ? Get involved on projects and contribute to Java directly ? Offered to do a lightning talk ? Coming soon: Java memory pub 5 Thursday, 14 July 2011
- 6. Dates? ? The thing that's bothering me at the moment is dating, there¡¯s several things to be aware of: ? Choosing a good restaurant ? What to wear ? .... 6 Thursday, 14 July 2011
- 7. Java Dates ? Java Date and Calendar ? Joda Time ? JSR-310 7 Thursday, 14 July 2011
- 8. Java Date ? Java Date has been in the language since January 23, 1996 ? Many good discussions about what¡¯s wrong with dates ? Mutability ? Date is a DateTime, but there are other classes for SQL ? No Timezones ? Not easy to use 8 Thursday, 14 July 2011
- 9. Calendar ? Still mutable ? Can¡¯t format a date directly 9 Thursday, 14 July 2011
- 10. Example From It¡¯s High Time @JavaOne 2008 ? How many bugs in this code? Date date = new Date(2007, 12, 13, 16, 40); TimeZone zone = TimeZone.getInstance ("Asia/HongKong"); Calendar cal = new GregorianCalendar (date, zone); DateFormat fm = new SimpleDateFormat ("HH:mm Z"); String str = fm.format(cal); 10 Thursday, 14 July 2011
- 11. Example From It¡¯s High Time @JavaOne 2008 ? 6 bugs in the code! Date date = new Date(2007, 12, 13, 16, 40); TimeZone zone = TimeZone.getInstance ("Asia/Hong_Kong"); Calendar cal = new GregorianCalendar (date, zone); DateFormat fm = new SimpleDateFormat ("HH:mm Z"); String str = fm.format(cal); 11 Thursday, 14 July 2011
- 12. Joda Time ? Instant ? Moment in time, represented by DateTime. DateTime is immutable ? Interval ? An interval of time from one instant to another. Both end points have same Chronology and TimeZone ? Duration ? Duration of time measured in milliseconds. No timezone of chronology applies 12 Thursday, 14 July 2011
- 13. Joda Time ? Period ? A period of time de?ned in terms of ?elds (e.g. +1 month) ? Chronology ? A calculation engine supporting complex calendar rules ? In most this can be ignored, important to the internal design, but not to the standard user using ISOChronology ? Timezones ? DateTimeZone zone = DateTimeZone.forID ("Europe/London"); 13 Thursday, 14 July 2011
- 14. JSR-310 ? Human/Machine Timelines ? Requirement to have a separation of concerns between human and machine timelines ? DateTime is better thought of as a LocalDateTime and a timezone ? Pluggable Chronology ? Restrict DateTime classes to a single calendar system ? Nulls ? Null means 0 in most cases, ouch! 14 Thursday, 14 July 2011
- 15. Getting Involved ? ThreeTen is now on GitHub ? Open project that can be contributed to ? A few pull requests have been made since moving to GitHub ? Accept the legal agreement ? Mailing List: threeten- develop@lists.sourceforge.net 15 Thursday, 14 July 2011
- 16. Contact ? James Gough ? jpgough@gmail.com ? Twitter: goughjam 3 16 Thursday, 14 July 2011