Riddle you this: Given a table of records with different
date and time. You have a requirement to retrieve the earliest record that
meets a specific date and time. The given time may be attached with a timezone. How would you implement this in Java?
Java does provide a package in java.util.date. Unfortunately, the package is timezone independent. In additions, adding or
subtracting a date by an amount of a month/day/year may not be an easy task too.
Here comes the Joda-Time library that can resolve your
problem. There are several advantages using Joda-Time:
- Joda-Time supports the ISO 8601 standard. A datetime specified in the ISO 8601 standard is represented as this: YYYY-MM-DDThh:mm:ss±hh:mm. This gives a universal representation of date-time.
- Better Parsing Rules - Joda-Time parses a date-time better than a SimpleDateFormatter. A date like "2014-02-31" is considered an error in Joda-Time, while a SimpleDateFormatter conversion may return a date as "2014-03-03".
Following is an example. The input parameter of a constructor is an ISO 8601 standardized date string.
import
org.joda.time.DateTime;
public class DateRequest {
private final DateTime asofdate;
public DateRequest(String dateInput)
{
this.date = new
DateTime(dateInput);
}
public boolean meet(Date date) {
return date.isAfter(new DateTime(date));
}
}
Remember, the constructor of a Joda-Time date-time class
accepts a NULL value, which returns an object with the current date-time of a timezone that specified from a machine. As your request may have come
from different parts of the world, the use of a NULL value constructor may lead
to some unwanted results.
For more details, you may go to Joda-Time website.
