Java创建dayOfWeek的日期和没有特定日期的时间，即对任何星期一有效

Question

How can I create a generic date (ie not attached to any actual yyMMdd but similar to:

val START = LocalTime.of(startHour, startMinute)
val END = LocalTime.of(endHour, endMinute)

However, I additionally want to include the dayOfWeek .

My intention is to calculate the overlap of time intervals, ie for two given (start, end) timestamps I want to calculate overlap with a specified weekday and time (ie like opening hours).

edit

I am not sure if a custom class is good enough. My intention is if I have a list of events like:

id,start,end
1,2018-01-01 08:00, 2018-01-01 08:00 || opening hours 8-10, duration: 1
2,2018-01-01 10:00, 2018-01-01 12:00 || opening hours 8-10, duration: 0
3,2018-01-02 10:00, 2018-01-02 12:00 || opening hours 10-15, duration 2

to validate if time interval of start-end intersects with another time interval (ie opening hours), but this other time interval depends on the day of week.

After constructing the object (where I currently have my probably as I can't combine dayOfWeek and Time in a generic way)

I would use isBefore/isAfter a couple of times and then calculate the duration of overlap.

Answer 1

Just use the DayOfWeek enum built into Java. It offers seven predefined objects, one for every day of the week, such as DayOfWeek.MONDAY .

I don't follow exactly your business problem, but it sounds like you need to define your own class.

public class Shift {
    DayOfWeek dayOfWeek ;
    LocalTime startTime , stopTime ;
}

Add a method that translates that into real moments.

public ZonedDateTime startAtDate( LocalDate ld , ZoneId z ) {
    LocalDate LocalDate = ld.with( TemporalAdjustors.previousOrSame( this.dayOfWeek ) ) ;
    ZonedDateTime zdt = ZonedDateTime.of( localDate , this.startTime , z ) ;
    return zdt ;
}

You'll likely want to add the ThreeTen-Extra library to your project. It offers classes such as Interval and LocalDateTime that you might find useful. These classes offer a bunch of comparison methods such as abuts , overlaps , etc.

Looks like that library lacks a LocalTimeRange , so might want to roll your own. Perhaps even donate such a class to that project.

---

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date , Calendar , & SimpleDateFormat .

The Joda-Time project, now in maintenance mode , advises migration to the java.time classes.

To learn more, see the Oracle Tutorial . And search Stack Overflow for many examples and explanations. Specification is JSR 310 .

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8 , Java SE 9 , Java SE 10 , Java SE 11 , and later - Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport .
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP… .

Answer 2

One simple approach is to use an enum map for those "standard" intervals.

Assuming the method below to calculate the overlap:

static int calculateOverlap(LocalTime expectedStartTime, LocalTime expectedEndTime, 
        LocalTime actualStartTime, LocalTime actualEndTime) {
    //calculate overlap...
}

You can look up the value in this way (using Pair for simplicity, you can use a custom class with two LocalTime fields):

Map<DayOfWeek, Pair<LocalTime, LocalTime>> openingHours = 
          new EnumMap<>(DayOfWeek.class);

openingHours.put(DayOfWeek.MONDAY, 
          Pair.of(LocalTime.of(8, 0), LocalTime.of(16, 0)));
openingHours.put(DayOfWeek.TUESDAY, 
          Pair.of(LocalTime.of(9, 0), LocalTime.of(17, 0)));
//...entries for other weekdays

And then look it up using:

MyEvent mondayEvent = ...

Pair<LocalTime, LocalTime> mondayHours = officialHours.get(DayOfWeek.MONDAY);
int overlap = calculateOverlap(mondayHours.getLeft(), mondayHours.getRight(),
        mondayEvent.getStart(), mondayEvent.getEnd());

Answer 3

My lib Time4J (v5.0) offers following out-of-box-solution for your whole business problem:

DayPartitionRule rule =
    new DayPartitionBuilder()
        .addWeekdayRule(
            Weekday.MONDAY,
            ClockInterval.between(PlainTime.of(8, 0), PlainTime.of(10, 0)))
        .addWeekdayRule(
            Weekday.TUESDAY,
            ClockInterval.between(PlainTime.of(10, 0), PlainTime.of(15, 0)))
        .build();
Map<Integer, TimestampInterval> events = new HashMap<>();
events.put(
    1,
    TimestampInterval.between(
        PlainTimestamp.of(2018, 1, 1, 8, 0),
        PlainTimestamp.of(2018, 1, 1, 9, 0)));
events.put(
    2,
    TimestampInterval.between(
        PlainTimestamp.of(2018, 1, 1, 10, 0),
        PlainTimestamp.of(2018, 1, 1, 12, 0)));
events.put(
    3,
    TimestampInterval.between(
        PlainTimestamp.of(2018, 1, 2, 10, 0),
        PlainTimestamp.of(2018, 1, 2, 12, 0)));
events.forEach(
    (id, interval) -> System.out.println(
        "Event: " + id + " => "
            + Duration.formatter(ClockUnit.class, "#h:mm").format(
                interval
                    .streamPartitioned(rule)
                    .map(i -> i.getDuration(ClockUnit.HOURS, ClockUnit.MINUTES))
                    .collect(Duration.summingUp())
                    .with(Duration.STD_CLOCK_PERIOD)
            )));

Output:

Event: 1 => 1:00

Event: 2 => 0:00

Event: 3 => 2:00

The algorithm uses the range-package of Time4J and still works properly if you have more than one clock interval per day-of-week or if the input interval stretches over more than one day (which requires summing up durations).

By the way, I assume that your first interval line "2018-01-01 08:00, 2018-01-01 08:00" contains a typo so I have adjusted the end time to 9AM (resulting in the expected duration of one hour).