Dates and Times—New API - Java - page 228

Seven hundred days from 2013-11-09 is 2015-10-10

Interfacing with Legacy Date and Calendar Classes

Problem

You need to deal with the old Date and Calendar classes.

Solution

Assuming you have code using the original java.util.Date and java.util.Calendar ,
you can convert values as needed using conversion methods.

Discussion

All the classes and interfaces in the new API were chosen to avoid conflicting with the tradi-
tional API. It is thus possible, and will be common for a while, to have imports from both
packages into the same code.

To keep the new API clean, most of the necessary conversion routines were added to the old
API . Table 6-7 summarizes these conversion routines; note that the methods are static if they
are shown being invoked with a capitalized class name, else they are instance methods.

Table 6-7. Legacy Date/Time interchange

Legacy Class Convert to legacy Convert to modern

java.util.Date date.from(Instant) Date.toInstant()

- java.util.Calendar calendar.toInstant()

java.util.GregorianCalendar GregorianCalendar.from(ZonedDateTime) calendar.toZonedDateTime()

-

java.util.TimeZone timeZone.toZoneId()

java.time.DateTimeFormatter - dateTimeFormatter.toFormat()

The following code shows some of these APIs in action: