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How can I get the current timestamp - x number of weeks using java.sql.Timestamp;

This is my current timestamp Timestamp.from(Instant.now(clock));

x- could be any number from 0-5

LoukasPap
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Neethu Lalitha
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  • Maybe this will help: https://stackoverflow.com/questions/23068676/how-to-get-current-timestamp-in-string-format-in-java-yyyy-mm-dd-hh-mm-ss – LoukasPap Aug 20 '20 at 20:43
  • Doesn’t this answer your question? [How to subtract X day from a Date object in Java?](https://stackoverflow.com/questions/11882926/how-to-subtract-x-day-from-a-date-object-in-java) – Ole V.V. Aug 21 '20 at 18:18
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    I recommend you don’t use `Timestamp`. That class is poorly designed and long outdated. Instead use either `OffsetDateTime`, `Instant`or `LocalDateTime`; all are from [java.time, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). – Ole V.V. Aug 22 '20 at 05:35

3 Answers3

4

Seeing the code provided, I would suggest to subtract the weeks from the Instant via Instant::minus. Since ChronoUnit.WEEKS is not supported by Instant::minus, we can convert the weeks in days by multiplying them with 7.

If changing the Instant is not an option, we could convert the Timestamp into an Instant, subtract, and convert back:

Timestamp.from(timestamp.toInstant().minus(x * 7L, ChronoUnit.DAYS));

Ideone demo

Or, if you are a friend of Optionals:

Optional.of(timestamp)
    .map(Timestamp::toInstant)
    .map(t -> t.minus(x * 7L, ChronoUnit.DAYS))
    .map(Timestamp::from);

Ideone demo

Turing85
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  • Why does it giv me : java.time.temporal.UnsupportedTemporalTypeException: Unsupported unit: Weeks – Neethu Lalitha Aug 20 '20 at 20:59
  • Timestamp.from(timestamp.toInstant().minus((line.hashCode() % 4) * 7L, ChronoUnit.WEEKS)) I still see UnsupportedTemporalTypeException. Here s the code I use – Neethu Lalitha Aug 20 '20 at 21:12
  • This answer assumes that a week is always 7 times 24 hours (168 hours), which isn’t always the case in real life, or more precisely, in real time zones. – Ole V.V. Aug 21 '20 at 18:20
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Using Instant Directly example, using local time:

Instant.now(Clock.systemDefaultZone()).minus(numberOfWeeks * 7L, ChronoUnit.DAYS);

Used in context:

public static void main(String[] args) {
    Instant now = Instant.now(Clock.systemDefaultZone());
    System.out.println("The time right now (local time): " + Timestamp.from(now));

    long numberOfWeeks = 3L;
    Instant minusXweeks = now.minus(numberOfWeeks * 7L, ChronoUnit.DAYS);
    System.out.println("The time 3 weeks before now (local time): " + Timestamp.from(minusXweeks));
}

Output:

The time right now (local time): 2020-08-20 23:24:58.077223
The time 3 weeks before now (local time): 2020-07-30 23:24:58.077223

NOTE:

Why not use ChronoUnit.WEEKS directly? See below:

Instant.now(Clock.systemDefaultZone()).minus(numberOfWeeks, ChronoUnit.WEEKS)

Seems like ChronoUnit.WEEKS is not supported by method java.time.Instant.minus while enum ChronoUnit.DAYS is. When using ChronoUnit.WEEKS in method java.time.Instant.minus then following exception is thrown:

Exception in thread "main" java.time.temporal.UnsupportedTemporalTypeException: Unsupported unit: Weeks
at java.base/java.time.Instant.plus(Instant.java:861)
at java.base/java.time.Instant.minus(Instant.java:978)
at TestClass.main(TestClass.java:18)
DigitShifter
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1

To subtract x weeks from the current time of the calendar, you can also try:

Calendar calendar = Calendar.getInstance();

calendar.add(Calendar.DAY_OF_MONTH, - (7 * no_of_weeks))

RahulMujnani
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