How can i customize date format in Java given inputs

Question

I want to write excel file date in format "dd/mm/yyyy hh:mm" an example of that is 12/03/2022 08:30

The problem is that i have all these values as parameters.. My fields stored in database are:

days : integer
month :  integer
year:integer
time :  float (example  08.00)

The goal is that i retrieve all of them and i want to combine and have a result of that "dd/mm/yyyy hh:mm".

Could i combine them to create that date format? I ask that because if i write that in excel as string maybe that type will causes problems with excel graphs etc..

It’s not clear what you’re asking. Are you asking how to concatenation strings, or parse a date in a given format, or both? — Dave Newton, Jun 04 '22 at 13:43
I will edit my question , but i think that i want both of them . — Tasos P, Jun 04 '22 at 13:44
Both of those questions should be answerable with a minimum of searching, on SO or the web in general. — Dave Newton, Jun 04 '22 at 13:45
@DaveNewton i posted because i cannot find solution till now.. — Tasos P, Jun 04 '22 at 13:49
`LocalDate.of(2022, 3, 12).atTime(LocalTime.ofSecondOfDay(Math.round(8.5 * Duration.ofHours(1).toSeconds()))).format(DateTimeFormatter.ofPattern("dd/MM/uuuu HH:mm"))` yields `12/03/2022 08:30`. Break up into more statements. And fill in the values from your database instead of 2022, 3, 12 and 8.5. — Ole V.V., Jun 04 '22 at 18:50

Cactusroot · Accepted Answer · 2022-06-05T07:22:06.107

Why don't you store a single long ("bigint") for the complete time? It is exact down to a millisecond and won't overflow in the next generations. You can get this time using System.currentTimeMillis() and use time classes like Date / LocalDateTime. They've got methods for everything.

With your approach:

hour:

Round your time towards 0.

minute:

Subtract hour from time.
- Now you've got your minute as a value from 0 (inclusive) to 1 (exclusive).
Multiply it by 60 to get it as a value from 0 (inclusive) to 60 (exclusive).

So the result looks like this:

int hour = (int) time;
int minute = (int) ((time - hour) * 60)
String timeString = days + "/" + month + "/" + year + " " + hour + ":" + minute;

How can i customize date format in Java given inputs

1 Answers1