find first and last date of the last month

Question

I have a simple but tricky code to write where I have given the date String of today in UTC time.

String s = Instant.now().toString().replaceAll("T.*", "");

I need to find the first and last days of the last month and store them in separate Strings. Any advice on how to achieve it best?

Please include sample data, and explain why you can't just use now() as suggested, and also expected output. — Joakim Danielson, Mar 04 '19 at 08:08
@JoakimDanielson I use the `import java.time.*` and don't want to mix up with many libraries. Besides, I need to be careful to know the current `UTC` date and find the first + last date of the last month. Ok, I just find they are indeed in the same library `java.time.LocalDate`. — Arefe, Mar 04 '19 at 08:19
Indeed, a duplicate... not sure why I don't get that in the Google search. — Arefe, Mar 05 '19 at 08:30

score 4 · Answer 1 · answered Mar 04 '19 at 08:12

You can make use of TemporalAdjusters.

If you don't have to start with a string, don't. Start with a LocalDate if possible.

If you have to start with a string, you can convert your string s to a LocalDate by parse:

LocalDate ld = LocalDate.parse(s);

Now we can get the start and end of the month like this:

LocalDate startOfMonth = ld.with(TemporalAdjusters.firstDayOfMonth());
LocalDate endOfMonth = ld.with(TemporalAdjusters.lastDayOfMonth());

I suggest you not to convert them to strings until the absolutely necessary (like you display it to the user).

score 4 · Answer 2 · answered Mar 04 '19 at 08:14

4

You can get using LocalDate

LocalDate startOfMonth = LocalDate.now().with(TemporalAdjusters.firstDayOfMonth());
LocalDate endOfMonth = LocalDate.now().with(TemporalAdjusters.lastDayOfMonth());

answered Mar 04 '19 at 08:14

Eklavya

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This code invokes the current date and gets the first day of the current month. The question is asking for the "LAST" month. – constantlyFlagged Aug 18 '22 at 09:11

score 3 · Answer 3 · answered Mar 04 '19 at 08:11

It's quite simple when using LocalDate and its date arithmetic functions:

LocalDate now = LocalDate.now();
LocalDate firstDayOfCurrentMonth = now.withDayOfMonth(1);

LocalDate firstDayOfLastMonth = firstDayOfCurrentMonth.minusMonths(1);
LocalDate lastDayOfLastMonth = firstDayOfCurrentMonth.minusDays(1);

Mark Melgo · Accepted Answer · 2019-03-04T08:29:37.967

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If you want to get the month before the current date then use the below code:

LocalDate today = LocalDate.now(ZoneOffset.UTC);  // Retrieve the date now
LocalDate lastMonth = today.minus(1, ChronoUnit.MONTHS); // Retrieve the date a month from now
System.out.println("First day: " + lastMonth.withDayOfMonth(1)); // retrieve the first date
System.out.println("Last day: " + lastMonth.withDayOfMonth(lastMonth.lengthOfMonth())); // retrieve the last date

edited Mar 04 '19 at 08:29

answered Mar 04 '19 at 08:13

Mark Melgo

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I would like to use `LocalDate now = LocalDate.now(ZoneOffset.UTC);` to set the `UTC` time. – Arefe Mar 04 '19 at 08:28
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@Arefe I have edited the answer – Mark Melgo Mar 04 '19 at 08:29

find first and last date of the last month

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