Featured White Papers

• Measuring Risk to Improve Java Software Quality
• Do You Really Get Classloaders?
• Pragmatic Continuous Delivery with Jenkins, Nexus, and LiveRebel
• Your Next Java Web App: Less XML, No Long Restarts, Fewer Hassles
• Coding with JRebel, Java Forever Changed
• 2012 Developer Productivity Report: Java Tools, Tech, Devs, and Data

Sponsored Links

• Graph databases are 1000x faster than relational.

  Learn More!

• Career opportunities at Harman- Careers That'll Rock Your Socks Off.

  Learn More!

• Developer-friendly Java PDF libraries by Qoppa Software

  Live Demos

• Stop blaming your app! Diagnose Java performance issues.

  Free tool >

• UrbanCode: Go From Continuous Integration to
  Continuous Delivery

  Learn More!

Sponsored Links

Optimize with a SATA RAID Storage Solution
Range of capacities as low as $1250 per TB. Ideal if you currently rely on servers/disks/JBODs

Java 101: The next generation: It's time for a change

Catching up with the Java Date and Time API

By Jeff Friesen, JavaWorld.com, 04/08/13

Page 5 of 7

LocalDate, LocalTime, and LocalDateTime

The java.time package provides LocalDate and LocalTime classes that model date and time values in an ISO calendar system and local time-zone context. They represent dates and times without taking time zones into consideration.

The java.time, LocalDateTime class combines LocalDate with LocalTime, for greater precision (date plus time) than you could achieve with LocalDate or LocalTime alone.

Instantiating LocalDate, LocalTime, and LocalDateTime

There are several categories of fluent factory methods for instantiating LocalDate, LocalTime, and LocalDateTime. These categories include the following:

• now() methods return instances created from clocks.
• of-prefixed methods return instances created from specific values.
• from-prefixed methods return instances created from other types (for example, obtaining a LocalDate instance from a LocalDateTime instance).

Local date and time classes: A demo

The application code in Listing 4 instantiates LocalDate, LocalTime, and LocalDateTime via some of the above fluent factory methods.

Listing 4. HumanTimeDemo.java (version 1)

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class HumanTimeDemo
{
   public static void main(String[] args)
   {
      // create from current date
      LocalDate localDate = LocalDate.now();
      System.out.printf("Local date = %s%n", localDate);

      // create from specific values
      localDate = LocalDate.of(2012, 12, 21);
      System.out.printf("Local date = %s%n", localDate);

      // create from 100 days into 1970
      localDate = LocalDate.ofEpochDay(100);
      System.out.printf("Local date = %s%n", localDate);
      
      // create from another local date
      localDate = LocalDate.from(localDate);
      System.out.printf("Local date = %s%n%n", localDate);


      // create from current time
      LocalTime localTime = LocalTime.now();
      System.out.printf("Local time = %s%n", localTime);

      // create from specific values
      localTime = LocalTime.of(9, 15);
      System.out.printf("Local time = %s%n", localTime);

      // create from 120 seconds past midnight
      localTime = LocalTime.ofSecondOfDay(120);
      System.out.printf("Local time = %s%n", localTime);

      // create from another local time
      localTime = LocalTime.from(localTime);
      System.out.printf("Local time = %s%n%n", localTime);


      // create from current date and time
      LocalDateTime localDateTime = LocalDateTime.now();
      System.out.printf("Local date and time = %s%n", localDateTime);
   }
}

Listing 4 reveals several ways to obtain local dates, times, and date-times. now() returns an instance based on the system clock in the default time zone; of returns an instance based on passed arguments; and from() returns an instance based on the same or another type.

Compile Listing 4 and run this application. Your output should be similar to the following:

Local date = 2013-03-23
Local date = 2012-12-21
Local date = 1970-04-11
Local date = 1970-04-11

Local time = 19:35:19.021
Local time = 09:15
Local time = 00:02
Local time = 00:02

Local date and time = 2013-03-23T19:35:19.021