The document discusses the new features of Java 8's date and time API (JSR-310), highlighting improvements over the previous java.util.Date and Calendar classes. It emphasizes the introduction of immutable classes like LocalDate, LocalTime, and ZonedDateTime, as well as new methods for parsing and formatting dates. The author also encourages community involvement in the Java Community Process (JCP) through initiatives like Adopt a JSR.

1. Java 8 Date Time
By Jim Gough
@JavaJimLondon

2. Agenda
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•
•
•
•
•
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Adopt a JSR
What exists in Java 7
New Things - The Basics
Working with Date and Time
Parsing and Formatting
Interoperability with java.util.Date
Advanced Queries
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3. Accompanying Materials
• Code along with github project:
• https:/
/github.com/jpgough/JavaTimeLab
!
• More information on my blog:
• http:/
/javajimlondon.blogspot.com/2014/01/
live-coding-on-java-8-date-time-api.html
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4. LJC/JCP
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LJC elected onto the JCP committee
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JCP (Java Community Process)
• The JCP is the mechanism for developing standard
technical specifications for the Java technology
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5. Adopt a JSR
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This is it! JSR-310 is the pilot
•
This program is intended to:
– Encourage members of the Java Community to get
involved in a JSR.
– Evangelise that JSR to the wider Java Community
community in order to increase grass roots
participation
– https:/
/java.net/projects/adoptajsr/pages/Home

6. Java Date
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Java Date has been in the language since January 23,
1996
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Many good discussions about what’s wrong with dates
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Mutability
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Date is a DateTime, but there are other classes for SQL
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No Timezones
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Not easy to use
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7. Calendar
• Still mutable
• Can’t format a date directly
• Performing arithmetic operations on
dates not clearly supported. For
example time between two points
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8. 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.getTimeZone("Asia/HongKong");
Calendar cal = new
GregorianCalendar(date, zone);
DateFormat fm = new
SimpleDateFormat("HH:mm Z");
String str = fm.format(cal);
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9. 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.getTimeZone("Asia/Hong_Kong");
Calendar cal = new
GregorianCalendar(date, zone);
DateFormat fm = new
SimpleDateFormat("HH:mm Z");
String str = fm.format(cal);
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10. New Things - The Basics
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New package java.time
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New objects for representing Dates and Time
– LocalDate
– LocalTime
– LocalDateTime
– ZonedDateTime
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11. Working with Date and Time
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Instant - Closest thing to java.util.Date
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Duration
– Measure of time. Eg 34.5 seconds
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Period
– A date based amount of time. Eg 5 days
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Difference important when working with
ZonedDateTime operations.
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12. Java.util.Date
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java.util.Date is actually closest to Instant
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Now has to toInstant method on
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Examples
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13. Parsing and Formatting
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DateTimeFormatter
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Nice predefined formatters:
– DateTimeFormatter.ISO_DATE
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Can build a custom pattern
– Some slight modification to patterns
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.format and .parse conveniently on objects.
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