Compare between two dates with time and timezone-CodePudding

I am developing a login functionality, where user is not allowed to login between some duration of time, and this is configurable. For example user is not allowed to login between

 {
  "fromDate": "2022-03-08",
  "toDate": 2022-03-15,
  "fromTime": "09:00",
  "toTime": "16:00",
  "timezone": "Canada/Toronto", 
  "days": [
    "Monday",
    "Tuesday",
    "Wednesday",
    "Saturday",
    "Sunday",
    "Thursday",
    "Friday"
  ]
}

Can anyone help in comparing fromDate and toDate with current User login time. I am tryin to convert all dates in UTC and then compare. As user can login anywhere so as per login time date may change in other country. Any suggestions/reference would be helpful.

CodePudding user response：

This appears to be a schoolwork assignment. So I’ll give a brief outline of the needed code, and let you fill in the details.

Parse your JSON into Java objects.

In the Java ecosystem, you have a choice of frameworks to assist in parsing JSON.

You need to end up with objects of the java.time classes as shown in code here.

LocalDate startDate = LocalDate.parse( "2022-03-08" ) ;
…
LocalTime startTime = LocalTime.parse( "09:00" ) ;
…
ZoneId z = ZoneId.of( "Canada/Toronto" ) ;
Set< DayOfWeek > dows = EnumSet.noneOf( DayOfWeek.class ) ;
dows.add( DayOfWeek.valueOf( "Monday".toUppercase() ) ;
…

Capture the current moment as seen with an offset from UTC of zero hours-minutes-days.

Instant instant = Instant.now() ;

Adjust into target time zone.

ZonedDateTime zdt = instant.atZone( z ) ;

Interrogate for the parts of that moment.

LocalDate ld = zdt.toLocalDate() ;
LocalTime lt = zdt.toLocalTime() ;
DayOfWeek dow = zdt.getDayOfWeek() ;

Compare to your limits.

if( ( ! ld.isBefore( startDate ) ) && ld.isBefore( endDate )  ) { … }
…
if( dows.contains( dow ) { … }

Regarding comparisons, I suggest you learn about Half-Closed versus Fully-Closed. I recommend consistent use of Half-Closed.

All these topics have been addressed many times already on Stack Overflow. So search to learn more.

CodePudding user response：

One practice is to use ZonedDateTime and put the zone at UTC or compare the offsetDateTime

    LocalDateTime ldtLowerBound = LocalDateTime.parse("2022-03-08T9:00:00");
    LocalDateTime ldtUpperBound = LocalDateTime.parse("2022-03-15T6:00:00");

    //For zonedDateTime
    ZonedDateTime zdt = ldtLowerBound.atZone(ZoneOffset.UTC);

    //For OffsetDateTime
    OffsetDateTime odt = ldtLowerBound.atOffset(ZoneOffset.UTC);

Then compare them with user localDateTime with your desired logic.