OCP Date, Time, and Localization 2

Question 1

Which Java class should you use to represent a single point in time as seconds since the Unix epoch?

Accepted Answer

Instant

Answer

Instant models a single instantaneous point on the timeline in epoch-seconds and nanosecond adjustment, independent of any time zone.

Question 2

What is the result of `LocalDate.of(2024, 1, 31).plusMonths(1)`?

Accepted Answer

2024-02-29

Answer

Java adjusts the day to the last valid day of the target month; February 2024 has 29 days (leap year), so the result is 2024-02-29.

Question 3

Which expression correctly calculates the total number of days between two LocalDate instances?

Accepted Answer

ChronoUnit.DAYS.between(date1, date2)

Answer

ChronoUnit.DAYS.between(date1, date2) returns the total elapsed days; Period.between().getDays() only returns the day component, not the total, and Duration.between() does not accept LocalDate.

Question 4

How do you convert a ZonedDateTime to the same instant in a different time zone?

Accepted Answer

zonedDateTime.withZoneSameInstant(ZoneId.of("Europe/London"))

Answer

withZoneSameInstant() converts the ZonedDateTime to a new zone while keeping the underlying instant the same, correctly shifting the wall-clock time.

Question 5

What is the output of `DateTimeFormatter.ofPattern("MM/dd/uuuu").format(LocalDate.of(2024, 6, 5))`?

Accepted Answer

"06/05/2024"

Answer

The pattern MM pads the month to 2 digits and dd pads the day to 2 digits, so month 6 becomes "06" and day 5 becomes "05", yielding "06/05/2024".

(OCP) Oracle Certified Professional Practice Test

(OCP) Oracle Certified Professional Practice Test

OCP Date, Time, and Localization 2