Core Date/Time Classes

Exam Objectives

Create and manage date-based and time-based events including a combination of date and time into a single object using LocalDate, LocalTime, LocalDateTime, Instant, Period, and Duration.
Define and create and manage date-based and time-based events using Instant, Period, Duration, and TemporalUnit.


1. The correct answer is D.
Option A is not valid. The method of() takes the year, month and day as arguments.
Option B is not valid. The method with() is not a static method.
Option C is not valid. Valid month values are from 1 to 12.
Option D is valid. The methods now() and plusDays() are valid and can be chained.

2. The correct answer is C.
The method atTime() of LocalDate returns a LocalDateTime object with the combined values of the LocalDate instance which calls the method and the time parameters passed.

3. The correct answers are B and D.
LocalTime doesn't store information about years and (complete) days.

4. The correct answers are B and C.
Option A is incorrect. Period implements TemporalAmount.
Option B is correct. java.time.Instant implements java.time.temporal.Temporal.
Option C is correct. LocalDate and LocalTime are immutable. Therefore, they are thread-safe.
Option D is incorrect. LocalDateTime doesn't store zone time information, it just returns the current date-time of the system.

5. The correct answer is A.
The valid ways to get the nanoseconds part of an Instant object are:

int nanos = i.getNano();


int nanos = now.get(ChronoField.NANO_OF_SECOND);

6. The correct answer is D.
Since the first argument is greater than the second, the result is a negative period. A Period counts complete months first, then days.

7. The correct answer is D.
If the parameters types are different, the second parameter is converted to the type of the first parameter. In this case, a LocalTime cannot be converted to a LocalDateTime (it misses the year, month, day part) and an exception is thrown.

8. The correct answers are A and C.
A LocalDate stores the year, month, days and related information. It doesn't store hours or milliseconds.