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Check whether a given Instant fits a defined Period

What we get is an Instant and a "date-grid" defined by a period (which defines the interval of datapoints, e.g.: Every Month, Every 3 Months, etc.) and a start date where we started that grid.
private Instant getValidDate(Instant request, Instant start, Period period) {
if(isOnGrid(request, start, period)) {
return request;
}
else {
return getNextPriorDateOnGrid(request, start, period);
}
}
An example:
Given are the following parameters:
request = Instant("2000-05-02T07:42:00.000Z") //Second May of 2000 7:42 AM
start = Instant("2000-01-01T06:00:00.000Z") //First January of 2000 6:00 AM
period = Period("3M") //Every 3 Months
isOnGrid(request, start, period); //Should return false
getNextPriorDate(request, start, period) //Should return the First April of 2000 6:00 AM
I really have no idea how to get this with reasonable performance (its a critical place in code)
How do you check whether a distant future date (given by the Instant) is exactly on this grid, and if not, what is the next past date that was on the grid?
EDIT: I forgot to mention: All times and dates are assumed to be in UTC Timezone

Here is a simple test case that should match your requirements:
package test;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
public class Java8PeriodAndInstant2 {
public static void main(String[] args) {
// LocalDate request=LocalDate.of(2000, 5, 2);
// LocalDate start=LocalDate.of(2000, 1, 1);
LocalDateTime start = Instant.parse("2000-01-01T06:00:00.000Z").atZone(ZoneId.of("UTC")).toLocalDateTime();
LocalDateTime request = Instant.parse("2000-05-02T07:42:00.000Z").atZone(ZoneId.of("UTC")).toLocalDateTime();
Period period = Period.ofMonths(3);
System.out.println("is on grid " + isOnGrid(request, start, period));
System.out.println("is on grid " + isOnGrid(LocalDateTime.of(2000, 4, 2,0,0), start, period));
System.out.println("is on grid " + isOnGrid(LocalDateTime.of(2000, 4, 1,0,0), start, period));
System.out.println("getNextPriorDate " + getNextPriorDate(request, start, period));
System.out.println("isOnGrid " + isOnGrid(Instant.parse("2000-01-03T05:00:00.000Z").atZone(ZoneId.of("UTC")).toLocalDateTime(), start, Period.ofDays(1)));
System.out.println("isOnGrid " + isOnGrid(Instant.parse("2000-01-03T06:00:00.000Z").atZone(ZoneId.of("UTC")).toLocalDateTime(), start, Period.ofDays(1)));
System.out.println("getNextPriorDate " + getNextPriorDate(Instant.parse("2000-01-03T05:00:00.000Z").atZone(ZoneId.of("UTC")).toLocalDateTime(), start, Period.ofDays(1)));
}
private static boolean isOnGrid(LocalDateTime start, LocalDateTime request, Period period) {
if (period.getDays() != 0) {
return ((Duration.between(start, request).toHours()%period.getDays())==0);
}
Period diffPeriod = Period.between(start.toLocalDate(), request.toLocalDate());
if (diffPeriod.getDays()!=0) {
return false;
}
if (period.getMonths() != 0) {
return ((diffPeriod.toTotalMonths()) % (period.toTotalMonths()) == 0);
}
if (diffPeriod.getMonths()!=0) {
return false;
}
if (period.getYears() != 0) {
return ((diffPeriod.getYears()) % (period.getYears()) == 0);
}
return false;
}
private static LocalDateTime getNextPriorDate(LocalDateTime request, LocalDateTime start, Period period) {
if (period.getDays() != 0) {
long hoursDiff=Duration.between(start, request).toHours();
return start.plusDays(hoursDiff/24);
}
Period diffPeriod = Period.between(start.toLocalDate(), request.toLocalDate());
if (period.getMonths() != 0) {
diffPeriod = diffPeriod.withDays(0);
long monthDiff = diffPeriod.toTotalMonths() % period.toTotalMonths();
return start.plus(diffPeriod).minusMonths(monthDiff);
}
if (period.getYears() != 0) {
diffPeriod = diffPeriod.withDays(0);
diffPeriod.withMonths(0);
long yearsDiff = diffPeriod.getYears() % period.getYears();
return start.plus(diffPeriod).minusYears(yearsDiff);
}
return null;
}
}
it works with periods of days or months or years.

You cannot add Periods to Instants. They have a different "scope".
An Instant i simply represents a point in the timeline, counting the amount of millis/nanos from a specific point in time called "Epoch".
At this instant i, the time at the clock at the wall (even the date in a calendar) differs around the world. It depends on the timezone you are in.
A Period respects different lengths of its representation among different timezones starting at differnt dates. For example: A month lasts 30 days in June but 31 days in August. And it is even more complex if daylight saving shifts occur.
An Instant has no idea, what a "month" actually is. You can parse it from a String and output it to it, but internally it does not represent a human understandable form of a month like 'Jan', 'Feb', ... .
This is, why you have to align an Instant to a LocalDateTime or ZonedDateTime using a ZoneId or an ZoneOffset. Theses classes understand and can work with Periods.
The following code converts your Instants to LocalDateTimes to take into account the above comments:
private static Instant getValidDate2(Instant request, Instant start, Period period)
{
assert(!request.isBefore(start));
// multiplication of period only works with days exclusive or
// zero daypart of period
assert(period.getDays() == 0 || (period.getMonths() == 0 && period.getYears() == 0));
ZoneId utcZone = ZoneOffset.UTC;
LocalDateTime ldstart = LocalDateTime.ofInstant(start, utcZone);
LocalDateTime ldreq = LocalDateTime.ofInstant(request, utcZone);
// calculate an approximation of how many periods have to be applied to get near request
Duration simpleDuration = Duration.between(ldstart, ldstart.plus(period));
Duration durationToReq = Duration.between(ldstart, ldreq);
int factor = (int) (durationToReq.toDays() / simpleDuration.toDays()); // rough approximation
// go near to request by a multiple of period
Period jump = Period.of(period.getYears() * factor, period.getMonths() * factor, period.getDays() * factor);
LocalDateTime ldRunning = ldstart.plus(jump);
// make sure ldRunning < request
while (ldRunning.isAfter(ldreq)) {
ldRunning = ldRunning.minus(period);
}
// make sure we pass request and
// save the the last date before or equal to request on the grid
LocalDateTime ldLastbefore = ldRunning;
while (!ldRunning.isAfter(ldreq)) {
ldLastbefore = ldRunning;
ldRunning = ldRunning.plus(period);
}
return ldLastbefore.equals(ldreq) ? request : ldLastbefore.atZone(utcZone).toInstant();
}
Explanation:
To avoid a loop adding period until it gets to request, a rough approximation is done on how often period must be added to start to come to request. A new period being a multiple of the request period is then added and aligned to get the last value of the grid which is less or equal to request. Depending on a comparation between the last value and request, the according instant is returned. In fact, the check is useless besides the fact, that request == request when it was on the grid and not only equal.
Here you can find further informations about java time: https://docs.oracle.com/javase/tutorial/datetime/overview/index.html

How do I figure out whether the current time is in between two times? [duplicate]

This question already has answers here:
How can I determine if a date is between two dates in Java? [duplicate]
(11 answers)
Closed 9 years ago.
I'm trying to write a schedule program in Java and I need to figure out what time it is, and whether the current time is in between two set times. Figuring out the current time is pretty simple, but do you have any suggestions for figuring out whether it is between two times of day. For example, it is 9:33 AM on a Thursday. So I would need to figure out which scheduled section of the week that time corresponds to. How would I go about comparing the time to set periods during the week, for example an Array of sectioned times during a week such as {Monday from 9-10 AM, Tuesday from 3-4 PM, Thursday from 8-11 AM}, and seeing which section of time the current time falls between?

An efficient way to find which period any date lies within would be to have a class;
public class TimePeriod implements Comparable<TimePeriod>{
Date start;
Date end;
//Constructor, getters, setters
boolean isIn(Date date) {
return date.after(start) && date.before(end);
}
public int compareTo(TimePeriod other) {
return start.compareTo(other.start);
}
}
..and then create a sorted list of TimePeriod where you can perform a binary search.
edit:
This might make the binary search easier;
int check(Date date) {
if (isIn(date)) {
return 0;
} else if (start.after(date)) {
return -1;
} else if (end.before(date)) {
return 1;
} else {
throw new IllegalStateException("Time has gone badly wrong");
}
}

If you're using Date Class, you could do it like this
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm");
Date before = sdf.parse("07/05/2012 08:00");
Date after = sdf.parse("07/05/2012 08:30");
Date toCheck = sdf.parse("07/05/2012 08:15");
//is toCheck between the two?
boolean isAvailable = (before.getTime() < toCheck.getTime()) && after.getTime() > toCheck.getTime();
EDITED
As suggested by Jonathan Drapeau you could also use compareTo.
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm");
Date before = sdf.parse("07/05/2012 08:00");
Date after = sdf.parse("07/05/2012 08:30");
Date toCheck = sdf.parse("07/05/2012 08:15");
//is toCheck between the two?
if you want to include the "initial" and "final" date range
boolean isAvailable = before.compareTo(toCheck) >= 0 && after.compareTo(toCheck) <= 0
if you want to exclude the "initial" and "final" date range
boolean isAvailable = before.compareTo(toCheck) > 0 && after.compareTo(toCheck) < 0
You could use it too on Calendar class.
Anyway, i highly recommend you to use Calendar. It's a way precise class
you could check it like this:
Calendar cal1 = Calendar.getInstance(); // for example 12:00:00
Calendar cal2 = Calendar.getInstance(); // for exmaple 12:30:00
Calendar userTime = Calendar.getInstance(); // time to test: 12:15:00
if(user.after(cal1)&& user.before(cal2)){
//...
}
And to initialize and set times to Calendar, check this:
http://www.tutorialspoint.com/java/util/calendar_settime.htm

I would suggest using the Epoch time.
For a definition of Epoch time: http://en.wikipedia.org/wiki/Epoch_time
Basically, its a number of seconds after a specific date, i believe in 1989. If you translate the 3 times (the current time and the 2 times to compare to) in epoch time you can just use > < = etc.
For information on getting epoch time, Try here (has many languages): http://shafiqissani.wordpress.com/2010/09/30/how-to-get-the-current-epoch-time-unix-timestamp/
Unfortunately, my java is lacking or I'd give you some code :)
Edit:
Java epoch time code:
long epoch = System.currentTimeMillis()/1000;
Because my Java is bad and I don't have an interpreter where I am, I can only suggest using this site to help convert the other dates to epoch time: http://www.epochconverter.com/

There is before(Date) and after(Date) method in Date Class.
secondDate.before(firstDate)

If you use Calendar class, it has explicit before() and after() methods:
Calendar startDate = ...
Calendar endData = ...
isBetween = currentDate.after(startDate) && currentDate.before(endDate);

how to check : dateOne < dateTwo

I need help to check following conditions related to date and time...
Calendar cal = Calendar.getInstance();
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
String CurrentDate= dateFormat.format(cal.getTime());
String ModifiedDate = dateTime taken from date n time picker widget ;
i have to check :
current ModifiedDate is not less than 5 minutes of current time
How to check this conditon in Android / Java..........?

Why are you formatting the date?
It's much easier to work with data in a "natural" representation rather than in a string representation. It's not clear whether your modified date has to be taken as a string, but if it does, the first thing you should do is parse it. You can then compare that with the current date and time using:
// Check if the value is later than "now"
if (date.getTime() > System.currentTimeMillis())
or
// Check if the value is later than "now + 5 minutes"
if (date.getTime() > System.currentTimeMillis() + TimeUnit.MINUTES.toMillis(5))
It's not really clear what you mean by "current ModifiedDate is not less than 5 minutes of current time" - whether you mean that it's not less than 5 minutes after, or not less than 5 minutes earlier, or something like that - but you should be able to change the code above to handle your requirements.
If you do a lot of date/time manipulation, I'd strongly recommend the use of Joda Time, which is a much better date/time API than java.util.Date/Calendar.

To check whether the given time is before/after the current time ,
There is a Calendar instance in Android...to compare date time values.
Calendar current_time = Calendar.getInstance ();
current_time.add(Calendar.DAY_OF_YEAR, 0);
current_time.set(Calendar.HOUR_OF_DAY, hrs);
current_time.set(Calendar.MINUTE, mins );
current_time.set(Calendar.SECOND, 0);
Calendar given_time = Calendar.getInstance ();
given_time.add(Calendar.DAY_OF_YEAR, 0);
given_time.set(Calendar.HOUR_OF_DAY, hrs);
given_time.set(Calendar.MINUTE, mins );
given_time.set(Calendar.SECOND, 0);
current_time.getTime();
given_time.getTime();
boolean v = current_calendar.after(given_calendar);
// it will return true if current time is after given time
if(v){
return true;
}

public static boolean getTimeDiff(Date dateOne, Date dateTwo) {
long timeDiff = Math.abs(dateOne.getTime() - dateTwo.getTime());
int day = (int) TimeUnit.MILLISECONDS.toHours(timeDiff);
int min= (int) ( TimeUnit.MILLISECONDS.toMinutes(timeDiff) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(timeDiff)));
if(day>1)
{
return false;
}
else if(min>5)
{
return false;
}
else
{
return true;
}
}
usage:
System.out.println(getTimeDiff(new Date("01/13/2012 12:05:00"),new Date("01/12/2012 13:00:00")));

get count back of DateTime that where within the correct range - Joda Time

I want to get the count back of DateTime that where within the correct range with Joda Time.
I have this version at the moment which is only good to check for a specific day:
public int getIntFatalitiesAtDay(DateTime AtDay) {
int resultCount = 0;
for( Fatality f : fatalities) {
if(Days.daysBetween(f.date, AtDay).getDays() == 0) {
resultCount++;
}
}
return resultCount;
}
This was usefull when i looped threw every day. However now i go by months with:
for (DateTime iDate = fa.firstDate; iDate.isBefore(fa.lastDate); iDate = iDate.plusMonths(1)) { ... }
And now i would like to get the count of fatalities that month.
Could someone help?
(Also from that year, althought i would like to see a option aswell where it doesn't look at the year but that's less important.)

Java's java.util.Date class has methods for determining if one date is before or after another. If you convert the DateTime objects to Date objects, you can do:
if (f.date.after(beginngingDate) && f.date.before(endingDate)).

How to compare two Joda time Periods

It does not seem straighforward.
I am trying this:
#Override
public int compare(Period o1, Period o2) {
return o1.toStandardDays().getDays() > o2.toStandardDays().getDays() ? -1 : (o1.toStandardDays().getDays() == o2.toStandardDays().getDays() ? 0 : 1);
}
But I get this exception:
java.lang.UnsupportedOperationException: Cannot convert to Days as this period contains months and months vary in length
at org.joda.time.Period.checkYearsAndMonths(Period.java:1455)
at org.joda.time.Period.toStandardDays(Period.java:1314)
I hoped Peroid would have an isLongerThan(Period p) method.

From the Joda Documentation:
To compare the actual duration of two periods, convert both to durations using toDuration, an operation that emphasises that the result may differ according to the date you choose.
The two toDuration methods are BasePeriod#toDurationTo(ReadableInstant) and BasePeriod#toDurationFrom(ReadableInstant). This means that you must choose either a start or end instant of this period in order to be able to compute its duration.
If that is a problem for you, then you might want to directly use Duration instead of Period.

As Matt Ball also explained in his answer, to compare 2 periods you need to convert them to a duration first. Durations are relative to a certain point in time, so you need to do something like this:
public static boolean isLonger(Period p1, Period p2) {
Instant now = Instant.now();
Duration d1 = p1.toDurationTo(now);
Duration d2 = p2.toDurationTo(now);
return d1.isLongerThan(d2);
}
public static boolean isShorter(Period p1, Period p2) {
Instant now = Instant.now();
Duration d1 = p1.toDurationTo(now);
Duration d2 = p2.toDurationTo(now);
return d1.isShorterThan(d2);
}

I wrote a method that should be able to compare two Periods to the nearest day (I didn't care about hours and minutes):
private int comparePeriods(Period period1, Period period2)
{
if (period1.getYears() != period2.getYears())
{
return Integer.compare(period1.getYears(), period2.getYears());
}
if (period1.getMonths() != period2.getMonths())
{
return Integer.compare(period1.getMonths(), period2.getMonths());
}
if (period1.getWeeks() != period2.getWeeks())
{
return Integer.compare(period1.getWeeks(), period2.getWeeks());
}
if (period1.getDays() != period2.getDays())
{
return Integer.compare(period1.getDays(), period2.getDays());
}
return 0;
}
Note that this method expects both periods to be normalised or it will not give accurate results.