Why can LocalDateTime return the instance?

Question

LocalDateTime is abstract class. So I cannot write:

LocalDateTime value = new LocalDateTime(); //error

If I want to get its instance, I have to write:

LocalDateTime value = LocalDateTime.now(); //not error

I have a question, Why can LocalDateTime return the instance? It's an abstract class.

I saw the overview, but I could not find it...

Answer 1

LocalDateTime is not an abstract class.

public final class LocalDateTime
    implements Temporal, TemporalAdjuster, ChronoLocalDateTime<LocalDate>, Serializable {

It has private constructors, so direct instantiation is not possible. Factory method such now(), now(ZoneId) etc are used to create instances.

Answer 2

LocalDateTime is an immutable date-time object that represents a date-time.

This class does not store or represent a time-zone. Instead, it is a description of the date. It cannot represent an instant on the time-line without additional information such as an offset or time-zone.

Hence it has static methods e.g.

LocalDateTime desc = LocalDateTime.now();