Don't forget that Date constructor happily accepts negative values.

Date date = new Date(Long.MIN_VALUE); 

returns

Sun Dec 02 22:47:04 BDT 292269055

I guess that's about the time of Big Bang dinosaurs :)

EDIT

As martin clayton answered, you can use the Calendar class to check the era. This will output 0 which stands for BCE:

Calendar calendar = Calendar.getInstance(); calendar.setTime(new Date(Long.MIN_VALUE)); System.out.println(calendar.get(Calendar.ERA)); 

If you are talking about java.util.Date as a timestamp you can do this

Date d = new Date(0L) and you will see this represents Thu Jan 01 01:00:00 GMT 1970

As tulskiy has pointed out it is possible to pass a negative value to the Date constructor. If we do this and use a date format that includes the era we can see:

Date d = new Date(Long.MIN_VALUE); DateFormat df = new SimpleDateFormat("EEE, d MMM yyyy G HH:mm:ss Z"); System.out.println(df.format(d)); 

displays: Sun, 2 Dec 292269055 BC 16:47:04 +0000

The other Answers may be correct but use outmoded classes.

java.time

The old date-time classes (java.util.Date/.Calendar etc.) have been supplanted by the java.time framework built into Java 8 and later.

The java.time classes are inspired by Joda-Time, defined by JSR 310, extended by the ThreeTen-Extra project, back-ported to Java 6 & 7 by the ThreeTen-Backport project, and adapted to Android in the ThreeTenABP project. See Tutorial.

For a moment on the timeline in UTC with a resolution of nanoseconds, use Instant. Given an offset-from-UTC, use OffsetDateTime. For a time zone (offset + rules for anomalies), use ZonedDateTime, but by its nature has no defined minimum, nor does ZoneId. For a date-only value without time-of-day and without time zone, use LocalDate. For a time-of-day only value without date and without time zone, use LocalTime. For date-time without time zone, use LocalDateTime.

• Instant.MIN = -1000000000-01-01T00:00Z
• OffsetDateTime.MIN = -999999999-01-01T00:00:00+18:00
• LocalDate.MIN = -999999999-01-01
• LocalTime.MIN = 00:00
• LocalDateTime.MIN = -999999999-01-01T00:00:00
• Year.MIN_VALUE = -999,999,999
• ZoneOffset.MIN = -18:00 (but -12:00 in practice)

Caution: Be wary of using these values as some kind of flag or special meaning. Many other software libraries and databases may not support these extreme values.

For a flag or special meaning such as a non-null "no value available", I suggest picking an arbitrary moment but avoid going to such extreme reaches either backward or forward in time. Perhaps the Unix epoch reference date, the first moment of 1970 in UTC, 1970-01-01T00:00:00Z. Defined as a constant in Java: Instant.EPOCH

It's the same as for the Calendar classes.

Try this:

Date d = new Date( Long.MIN_VALUE ); System.out.println( d ); 

You'll see:

Sun Dec 02 16:47:04 GMT 292269055 

But the default date format doesn't include the era - which is BCE for this date.

LocalDateTime MIN defines the minimum supported LocalDateTime, '-999999999-01-01T00:00:00'. This is the local date-time of midnight at the start of the minimum date.

public static final LocalDateTime MIN; this is the MIN syntax;

import java.time.LocalDateTime; public class Main { public static void main(String[] args) { LocalDateTime a = LocalDateTime.MIN; System.out.println(a); } }