Suppose the following snippet:
LocalTime test = LocalTime.of(21, 14);
test.plusHours(5);
The result would be, normally, 02:14 but I want to sum beyond the 24 hour limit, so the result would be 26:14.
In this case I have a field that an user can input how much time it spent on a task. However I have to work with hours (eg 48 hours) instead of days (eg 2 days and 4 hours).
Is there a way that I can achieve that within the java.time API? If not, what can I do to achieve that? I am using Java 8, with Spring Boot and Hibernate to map the database.
java.time.Duration
You’re using the wront data type for the value. You need a Duration. Duration is the time-level counterpart of Period:
A time-based amount of time, such as '34.5 seconds'.
Duration durationTaken = Duration.of(5, ChronoUnit.HOURS);
If you want to relate that to a date concept, such as to compute the end time, you can plus durations to date/time types:
LocalTime endTime = test.plus(durationTaken); //02:14
And you can do that with LocalDateTime too:
LocalDateTime startTime = LocalDateTime.of(LocalDate.now(), test); //2019-02-07T21:14
//add the duration:
LocalDateTime endDate = startTime.plus(durationTaken); //2019-02-08T02:14
To specify how long a task takes, use Duration:
Duration initialDuration = Duration.ofHours(21).plusMinutes(34);
Duration afterFurtherWork = initialDuration.plusHours(5);
System.out.printf("Total duration was %2d hours and %02d minutes.%n",
afterFurtherWork.toHours(), afterFurtherWork.toMinutesPart());
Update: as Ole V.V. points out, toMinutesPart was added in Java 9. If still using Java 8, use toMinutes()%60.
LocalTime won't support this. It has a static initializer with some very baked in rules around 24 hours.
/**
* Constants for the local time of each hour.
*/
private static final LocalTime[] HOURS = new LocalTime[24];
static {
for (int i = 0; i < HOURS.length; i++) {
HOURS[i] = new LocalTime(i, 0, 0, 0);
}
MIDNIGHT = HOURS[0];
NOON = HOURS[12];
MIN = HOURS[0];
MAX = new LocalTime(23, 59, 59, 999_999_999);
}
Based on your updated comments, I might suggest converting hours to your lowest time value, i.e. with TimeUnit.HOURS.toMinutes(value).
Related
I have been trying to figured out an algorithm to return a list of time based on a start time and end time and how many loop. For example the start time at 6 am and the end time at 10 pm and the looping number is 5 so I need to return 22-6 = 16 and 16/5 = 3.2 so I need to return
6:00:00
9:20:00
12:40:00
15:60:00
18:20:00
21:40:00
I need to return such these values. (Note, the return value I wrote are not accurate but just for the purpose of demonstration)
The current code:
// List<Time> times(int looping){
long test(){
List<Time> result = new ArrayList<Time>();
String start = "06:00:00";
String finish = "22:00:00";
Time startTime = Time.valueOf(start);
Time endTime = Time.valueOf(finish);
long totalHours = endTime.getTime() - startTime.getTime();
return totalHours;
// return result;
}
Note: the long totalHours return a strange number not 16 and I'm not sure how to loop throw time and return the wanted values.
java.time
This is one of the places where java.time, the modern Java date and time API, excels. The method Duration::dividedBy does just want you want, dividing a span of time into a certain number of chunks.
List<LocalTime> result = new ArrayList<>();
String start = "06:00:00";
String finish = "22:00:00";
LocalTime startTime = LocalTime.parse(start);
LocalTime endTime = LocalTime.parse(finish);
Duration totalTime = Duration.between(startTime, endTime);
int subintervalCount = 5;
Duration subintervalLength = totalTime.dividedBy(subintervalCount);
LocalTime currentTime = startTime;
for (int i = 0; i < subintervalCount; i++) {
result.add(currentTime);
currentTime = currentTime.plus(subintervalLength);
}
System.out.println(result);
This outputs:
[06:00, 09:12, 12:24, 15:36, 18:48]
Where did the strange number of total hours come from?
the long totalHours return a strange number not 16 and I'm not sure
how to loop throw time and return the wanted values.
The Time class doesn’t define a getTime method. Instead you are calling the getTime method of the superclass java.util.Date, another poorly designed and long outdated class that we should no longer use. This getTime retunrs the count of milliseconds since the epoch of 1970-01-01T00:00:00 UTC, something that does not make sense for a time of day. I consider it likely that your subtraction yielded the number of milliseconds rather than the number of hours between your two times.
Edit: In case you’re curious and want to check: 16 hours equals 57 600 000 milliseconds. I obtained the number from TimeUnit.HOURS.toMillis(16).
Link
Oracle tutorial: Date Time explaining how to use java.time.
I have a program that is intaking an "AM" "PM" time and calculating out the hours in the day equivalent (in 24 hour format). For some reason it parses and calculates the time I input to the incorrect 24 hour equivalent (ie 5:00 pm comes to equal 22)
System.out.print("Enter the end time (HH:MM am): ");
endTime = input.nextLine();
Date ETime = time_to_date.parse(endTime);
Class method
public int get_Family_A_Calulation(Date STime, Date ETime) {
Date startTimeCalc = STime, endTimeCalc = ETime;
int pay = 0, hoursWorked, StartHour, EndHour;
StartHour = ((((int) startTimeCalc.getTime()) / 1000) / 60) / 60;
EndHour = ((((int) endTimeCalc.getTime()) / 1000) / 60) / 60;
pay = hoursWorked * 15;
return pay;
}
I am not sure where my error is can anyone give me advice on how to correct this error?
Use the latest classes available fron java8
LocalDateTime now = LocalDateTime.now();
System.out.println(now.getHour());
The actual data behind Date is milliseconds since the epoch. Any hour or time representation is based on the calendar date portion and takes into account timezone and daylight savings.
Regardless of what you do, there will be calculation issues across days, etc.
As suggested by Scary Wombat, use the new classes in java.time package. For your specific case, you need a LocalTime as the code is trying to represent a time element (hours, minutes, seconds, etc) without consideration for Date, TimeZone, etc.
https://docs.oracle.com/javase/8/docs/api/java/time/LocalTime.html
I have variables which store the values
int day = Calender.SATURDAY;
int hour = 18;
int minutes = 33;
How can I convert this to Date? so
How I can find the time difference in milliseconds from Current date time?
Cases :
If the current date, time pass already passed,
for example: If the current day is Saturday, and now time is 19: 00, than get the next week date time interval.
If the current day is Saturday, and now time is 18: 30,
(the time interval should be 180000 milliseconds = 3 minutes).
How can I do this in android?
Please help me with finding the proper solution for this problem.
Create a Calendar (Calendar.getInstance()), set your fields (cal.set(Calendar.DAY, day), etc.) and then call getTime() on it - that will return a Date.
For a proper solution I strongly advise to use the modern functions provided by java.time instead of the deprecated java.util. Read this post and Convert java.util.Date to what “java.time” type? to understand the package. How to get java.time on android pre API 26 is described here: How to use ThreeTenABP in Android Project
If you have read those you can solve your problem along the lines of this example:
public void dateStuff() {
int day = DayOfWeek.SATURDAY.getValue();
int hour = 18;
int minutes = 33;
LocalDateTime now = LocalDateTime.now();
int dayDifference = now.getDayOfWeek().getValue() - day;
LocalDateTime date = LocalDateTime.of(now.getYear(), now.getMonth(), now.getDayOfMonth() - dayDifference, hour, minutes);
long timeDifferenceNano = Duration.between(now, date).getNano();
long timeDifference = TimeUnit.NANOSECONDS.toMillis(timeDifferenceNano);
if (timeDifference > TimeUnit.MINUTES.toMillis(3)) {
//do stuff
}
}
Unfortunately I did not really understand when the two cases come into play, but I'm sure you can take it from here.
I have a map of string values which represent down times for different components.
dependencyMap.put ("sut", "14:26:12,14:27:19,00:01:07;15:01:54,15:02:54,00:01:00;15:44:30,15:46:30,00:02:00;16:10:30,16:11:30,00:01:00");
dependencyMap.put ("jms", "14:26:12,14:28:12,00:02:00;15:10:50,15:12:55,00:02:05;15:42:30,15:43:30,00:01:00;16:25:30,16:27:30,00:02:00");
The strings represent the start, end and duration of down times.
(start)14:26:12,(end)14:27:19,(duration)00:01:07
I read the values in, then add them to a list of DependencyDownTime objects which hold the Long values startTime, endTime and duration.
jArray.forEach (dependency ->{
String downTimeValues = knownDowntimesMap.get(dependency);
final String[] downtime = downTimeValues.split (";");
for (final String str : downtime) {
final DependencyDownTime depDownTime = new DependencyDownTime ();
final String[] strings = str.split (",");
if (strings.length == 3) {
final DateFormat dateFormat = new SimpleDateFormat ("HH:mm:ss");
try {
depDownTime.setStartTime(dateFormat.parse (strings[0]).getTime ());
depDownTime.setEndTime (dateFormat.parse (strings[1]).getTime ());
depDownTime.setDuration (dateFormat.parse (strings[2]).getTime ());
downTimes.add (depDownTime);
} catch (final ParseException e) {
//logger.warn (e.getMessage (), e);
}
} else {
//logger.warn ("");
}
}
I then perform simple arithmetic on the values, which calculates the total down time for each component.
// sort the list by start time
Collections.sort(downTimes, Comparator.comparing (DependencyDownTime::getStartTime));
int i = 1;
Long duration = 0L;
for(DependencyDownTime dts: downTimes){
Long curStart = dts.getStartTime ();
Long curEnd = dts.getEndTime();
Long nextStart = downTimes.get(i).getStartTime ();
Long nextEnd = downTimes.get(i).getEndTime ();
if(duration == 0){
duration = dts.getDuration();
}
if(curStart.equals(nextStart) && curEnd < nextEnd){
duration += (nextEnd - curEnd);
}
else if(nextStart > curEnd){
duration += downTimes.get(i).getDuration();
}
else if( curStart < nextStart && curEnd > nextStart){
duration += (nextEnd - curEnd);
}
else if(curEnd == nextStart){
duration += downTimes.get(i).getDuration();
}
i++;
if(i == downTimes.size ()){
componentDTimeMap.put (application, duration);
return;
}
The expected values should be something like 1970-01-01T 00:14:35 .000+0100, a matter of minutes. The actual result is usually extremely high off by a matter of hours in the difference 1969-12-31T 15:13:35 .000+0100
I have 2 questions.
Am I parsing the values correctly?
If my calculations are a little off when adding and subtracting the long values. When I convert the values back to Date format will there be a drastic difference in the expected value?
As explained in your other question, don't mistake those 2 different concepts:
a time of the day: it represents a specific point of a day, such as 10 AM or 14:45:50
a duration: it represents an amount of time, such as "1 hour and 10 minutes" or "2 years, 3 months and 4 days". The duration doesn't tell you when it starts or ends ("1 hour and 10 minutes" relative to what?), it's not attached to a chronology, it doesn't correspond to a specific point in the timeline. It's just the amount of time, by itself.
In your input, you have:
(start)14:26:12,(end)14:27:19,(duration)00:01:07
The start and end represents times of the day, and the duration represents the amount of time. SimpleDateFormat is designed to work with dates and times of the day, but not with durations. Treating the duration as a time of the day might work, but it's a hack as explained in this answer.
Another problem is that when SimpleDateFormat parses only a time, it defaults the day to January 1st 1970 at the JVM default timezone, leading to all the strange results you see. Unfortunately there's no way to avoid that, as java.util.Date works with full timestamps. A better alternative is to use the new date/time API.
As in your other question you're using Java 8, I'm assuming you can also use it here (but if you're using Java <= 7, you can use the ThreeTen Backport, a great backport for Java 8's new date/time classes. The only difference is the package names (in Java 8 is java.time and in ThreeTen Backport (or Android's ThreeTenABP) is org.threeten.bp), but the classes and methods names are the same).
As you're working only with times, there's no need to consider date fields (day/month/year), we can use a LocalTime instead. You can parse the strings directly, because they are in ISO861 compliant format:
LocalTime start = LocalTime.parse("14:26:12");
LocalTime end = LocalTime.parse("14:27:19");
Unfortunately there are no built-in parsers for a duration, so you'll have to parse it manually:
// parse the duration manually
String[] parts = "00:01:07".split(":");
Duration d = Duration
// get hours
.ofHours(Long.parseLong(parts[0]))
// plus minutes
.plusMinutes(Long.parseLong(parts[1]))
// plus seconds
.plusSeconds(Long.parseLong(parts[2]));
Another alternative is to remove the durations from your input (or ignore them) and calculate it using the start and end:
Duration d = Duration.between(start, end);
Both will give you a duration of 1 minute and 7 seconds.
My suggestion is to change the DependencyDownTime to store start and end as LocalTime objects, and the duration as a Duration object. With this, your algorithm would be like this:
Duration total = Duration.ZERO;
for (...) {
LocalTime curStart = ...
LocalTime curEnd = ...
LocalTime nextStart = ...
LocalTime nextEnd = ...
if (total.toMillis() == 0) {
duration = dts.getDuration();
}
if (curStart.equals(nextStart) && curEnd.isBefore(nextEnd)) {
total = total.plus(Duration.between(curEnd, nextEnd));
} else if (nextStart.isAfter(curEnd)) {
total = total.plus(downTimes.get(i).getDuration());
} else if (curStart.isBefore(nextStart) && curEnd.isAfter(nextStart)) {
total = total.plus(Duration.between(curEnd, nextEnd));
} else if (curEnd.equals(nextStart)) {
total = total.plus(downTimes.get(i).getDuration());
}
i++;
if (i == downTimes.size()) {
// assuming you want the duration as a total of milliseconds
componentDTimeMap.put(application, total.toMillis());
return;
}
}
You can either store the Duration object, or the respective value of milliseconds. Don't try to transform it to a Date, because a date is not designed nor supposed to work with durations. You can adapt this code to format a duration if you want (unfortunately there are no native formatters for durations).
Limitations
The code above assumes that all start and end times are in the same day. But if you have start at 23:50 and end at 00:10, should the duration be 20 minutes?
If that's the case, it's a little bit trickier, because LocalTime is not aware of the date (so it considers 23:50 > 00:10 and the duration between them is "minus 23 hours and 40 minutes").
In this case, you could do a trick and assume the dates are all at the current date, but when start is greater than end, it means that end time is in the next day:
LocalTime start = LocalTime.parse("23:50");
LocalTime end = LocalTime.parse("00:10");
// calculate duration
Duration d;
if (start.isAfter(end)) {
// start is after end, it means end is in the next day
// current date
LocalDate now = LocalDate.now();
// start is at the current day
LocalDateTime startDt = now.atTime(start);
// end is at the next day
LocalDateTime endDt = now.plusDays(1).atTime(end);
d = Duration.between(startDt, endDt);
} else {
// both start and end are in the same day
// just calculate the duration in the usual way
d = Duration.between(start, end);
}
In the code above, the result will be a Duration of 20 minutes.
Don't format dates as durations
Here are some examples of why SimpleDateFormat and Date aren't good to handle durations of time.
Suppose I have a duration of 10 seconds. If I try to transform it to a java.util.Date using the value 10 to a date (AKA treating a duration as a date):
// a 10 second duration (10000 milliseconds), treated as a date
Date date = new Date(10 * 1000);
System.out.println(date);
This will get a date that corresponds to "10000 milliseconds after unix epoch (1970-01-01T00:00Z)", which is 1970-01-01T00:00:10Z. But when I print the date object, the toString() method is implicity called (as explained here). And this method converts this millis value to the JVM default timezone.
In the JVM I'm using, the default timezone is America/Sao_Paulo, so the code above outputs:
Wed Dec 31 21:00:10 BRT 1969
Which is not what is expected: the UTC instant 1970-01-01T00:00:10Z corresponds to December 31st 1969 at 9 PM in São Paulo timezone.
This happens because I'm erroneously treating the duration as a date (and the output will be different, depending on the default timezone configured in the JVM).
A java.util.Date can't (must not) be used to work with durations. Actually, now that we have better API's, it should be avoided whenever possible. There are too many problems and design issues with this, just don't use it if you can.
SimpleDateFormat also won't work properly if you handle the durations as dates. In this code:
SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
Date d = dateFormat.parse("10:00:00");
The input has only time fields (hour, minute and second), so SimpleDateFormat sets the date to January 1st 1970 at the JVM default timezone. If I System.out.println this date, the result will be:
Thu Jan 01 10:00:00 BRT 1970
That's January 1st 1970 at 10 AM in São Paulo timezone, which in UTC is equivalent to 1970-01-01T13:00:00Z - so d.getTime() returns 46800000.
If I change the JVM default timezone to Europe/London, it will create a date that corresponds to January 1st 1970 at 10 AM in London (or UTC 1970-01-01T09:00:00Z) - and d.getTime() now returns 32400000 (because 10 AM in London and 10 AM in São Paulo happened at different instants).
SimpleDateFormat isn't the right tool to work with durations - it isn't even the best tool to work with dates, actually.
Example:
LocalTime time1 = LocalTime.of(12, 30);
LocalTime time2 = LocalTime.of(8, 30);
time1 + time2 // Doesn't work.
time1.plus(time2) // Doesn't work.
I want to get the sum of the two times (12:30 + 8:30 = 21:00) in the format of (hours:minutes).
Any other suggestions?
You are trying to add two LocalTime variables. This is wrong as a concept. Your time2 should not be a LocalTime, it should be a Duration. A duration added to a time gives you another time. A time subtracted from a time gives you a duration. It is all nice and logical. Adding two times together is not.
It is possible with some hacking to convert your time to a duration, but I would strongly advise against that. Instead, restructure your code so that time2 is a Duration in the first place.
You can do the following...
LocalTime t1 = LocalTime.of(9, 0); // 09:00
LocalTime t2 = LocalTime.of(2, 30); // 02:30
LocalTime total = t1.plusHours(t2.getHour())
.plusMinutes(t2.getMinute()); // 11:30
The answer of Mike Nakis does not true.
The above sentence of mine doesn't true. I have checked and only Java 8 has LocalTime.of so Mike Nakis's answer is perfectly true. Please see his answer.
[This section still keep. in case LocalTime in joda library ]
I will explain:
A duration in Joda-Time represents a duration of time measured in milliseconds. The duration is often obtained from an interval. i.e. we
can subtract start from end of an interval to derive a duration.
A period in Joda-Time represents a period of time defined in terms of fields, for example, 3 years 5 months 2 days and 7 hours. This
differs from a duration in that it is inexact in terms of
milliseconds. A period can only be resolved to an exact number of
milliseconds by specifying the instant (including chronology and time
zone) it is relative to. e.g. consider the period of 1 year, if we add
this to January 1st we will always arrive at the next January 1st but
the duration will depend on whether the intervening year is a leap
year or not.
LocalTime is an immutable time class representing a time without a time zone. So, base on above definition, period is suitable for you adding time to LocalTime. In fact, API has proved this:
LocalTime localTime = new LocalTime(10, 30);
Duration d = new Duration(1, 0);
Period p = new Period(1, 0);
LocalTime newLocalTime = localTime.plus(d); // COMPILE ERROR
LocalTime newLocalTime = localTime.plus(p); // SUCCESS
you can use the method sum()
LocalTime time1 = LocalTime.of(12, 30);
LocalTime time2 = LocalTime.of(8, 30);
Integer hour1 = time1.getHour();
Integer hour2 = time2.getHour();
Integer minute1 = time1.getMinute();
Integer minute2 = time2.getMinute();
Integer first = Integer.sum(hour1,hour2);
Integer second = Integer.sum(minute1,minute2);
System.out.println("The time is "+ first + " : " + second);
It must work
LocalTime t1 = LocalTime.parse('03:33:24')
LocalTime t2 = LocalTime.parse('03:13:41')
t1.plusHours(t2.hour)
.plusMinutes(t2.minute)
.plusSeconds(t2.second)
.plusNanos(t2.nano)