minus 1 hour to DateTime using Joda Time - java

I just want to subtract 1 hour from a DateTime I tried looking it up on Google and I found that there is a method called minus that takes a copy of the date and take a specific duration right here: http://www.joda.org/joda-time/apidocs/org/joda/time/DateTime.html#minus(long)
But I don't know how to use it and I can't an find a example on the internet.
Here's my code:
String string1 = (String) table_4.getValueAt(0, 1);
String string2= (String) table_4.getValueAt(0, 2);
DateTimeFormatter dtf = DateTimeFormat.forPattern("hh:mm a").withLocale(Locale.ENGLISH);
DateTime dateTime1 = dtf.parseDateTime(string1.toString());
DateTime dateTime2 = dtf.parseDateTime(string2.toString());
final String oldf = ("hh:mm a");
final String newf= ("hh.mm 0");
final String newf2= ("hh.mm a");
final String elapsedformat = ("hh.mm");
SimpleDateFormat format2 = new SimpleDateFormat(oldf);
SimpleDateFormat format2E = new SimpleDateFormat(newf);
Period timePeriod = new Period(dateTime1, dateTime2);
PeriodFormatter formatter = new PeriodFormatterBuilder()
.appendHours().appendSuffix(".")
.appendMinutes().appendSuffix("")
.toFormatter();
String elapsed = formatter.print(timePeriod);
table_4.setValueAt(elapsed,0,3);
DecimalFormat df = new DecimalFormat("00.00");
System.out.println(dateTime1);
table_4.setValueAt("", 0, 4);
table_4.setValueAt("", 0, 5);
Sample Data:
dateTime1: 08:00 AM
dateTime2: 05:00 PM
the period will be 9 hours. but i want it to be 8 hrs only because i want to subtract the lunch break in my program.
i tried it with this stupid code:
dateTime1.minus(-1)
I also tried parsing string1 to double so I can subtract it by one.
double strindtoD = Integer.parseInt(string1);
I also tried making another DateTime and use period to get the difference of the two time
String stringOneHour = ("01:00 AM");
DateTime dateTime3 = dtf.parseDateTime(stringOneHour.toString());
Period timePeriod = new Period(dateTime3, dateTime1);

Just use:
dateTime.minusHours(1)
This is documented in the API.
Note that DateTime objects are immutable, so the operation alone has no effect. You need to assign the result of this method to a new object (or replace itself):
dateTime = dateTime.minusHours(1);
As to how to obtain a Period out of the difference between two DateTimes, you must first go through an Interval:
Period period = new Interval(begin, end).toPeriod();
Link to a SO post explaining why there is both Period and Interval.
Side note: Joda Time uses a LOT of indirections in its API; as such reading the Javadoc not only requires one to read the methods for one class, but also look at the list of inherited methods from all the inherited abstract classes/interfaces; for instance, a DateTime is also a ReadableInstant. One you get used to it, though, it's a breeze.

If you are using an older version of org.joda.time.DateTime then you can use minus(ReadablePeriod period) method like this
Date date = LocalDate.now().minus(new Period(1, 0, 0, 0)).toDate();
where Period accepts int hours, int minutes, int seconds, int millis parameters

By using Calender class object you can use this method to subtract hours.
cal.add(Calendar.HOUR_OF_DAY, -numberOfHours);
and also here is complete example link

Related

Subtract char of digits like normal integers

I have two strings which can be seen as time stamps:
String min="2017-04-15 13:27:31";
String max="2017-04-15 13:40:01";
Assume we want to find out the time passed from first time stamp to the second one. If there was only the time and no date included, I could get it using my following code:
String[] partsMin=min.split(":");
String[] partMax=max.split(":");
int diffZero=Integer.parseInt(partMax[0])-Integer.parseInt(partsMin[0]);
int diffOne=Integer.parseInt(partMax[1])-Integer.parseInt(partsMin[1]);
int diffOTwo=Integer.parseInt(partMax[2])-Integer.parseInt(partsMin[2]);
diffInSec=diffZero*3600+diffOne*60+diffOTwo;
So here is the question. How to get the job done while there is a date within the time stamp?
I would construct LocalDateTime instances from it.
Then i would get the milliseconds from it and substract startTime from EndTime.
What is remaining are the milliseconds passed between the two. A DateTimeFormatter is helpful as well for this purpose.
String strMin = "2017-04-15 13:27:31";
DateTimeFormatter formatterTime = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime dateTimeMin = LocalDateTime.parse(strMin, formatter);
String strMax = "2017-04-15 13:40:01";
LocalDateTime dateTimeMax = LocalDateTime.parse(strMax, formatter);
long minutes = ChronoUnit.MINUTES.between(dateMin, dateMaxto);
long hours = ChronoUnit.HOURS.between(dateMin, dateMax);
If you want to get the milliseconds:
long millisPassed = dateMax.toEpochMilli() - dateMax.toEpochMilli();
Use the java date time libraries (even the old Date class would be fine for this) to parse the string into a proper object.
Depending on the date time library you chose you can then look at the difference between them. The simplest would be something like:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
Date date1 = sdf.parse(str1);
Date date2 = sdf.parse(str2);
long differenceInSeconds = (date2.getTime()-date1.getTime())/1000;
The new Java 8 time classes would also allow you to do this and would be better to learn going forwards. I can't remember the syntax for that off the top of my head though.
Did you try with replace all the other part of your String like this :
String[] partsMin = min.replaceAll("\\d+-\\d+-\\d+", "").trim().split(":");
String[] partMax = max.replaceAll("\\d+-\\d+-\\d+", "").trim().split(":");
Doing this in your code:
int diffZero=Integer.parseInt(partMax[0])
is the same as doing:
int diffZero=Integer.parseInt("2017-04-15")
that is generating an Exception(NumberFormatException)
you should better try to PARSE those strings min and max into a date
Edit:
you can inspect your code/ variables: and see that splitting to ":" is not giving you back the correct array since the element at index 0 is holding more information than you need...
but as I said before, you are going on the wrong path, dont re invent the wheel and look how practical will get using the APIs that java has for us:
String min = "2017-04-15 13:27:31";
String max = "2017-04-15 13:40:01";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime dateTimeMin = LocalDateTime.parse(min, formatter);
LocalDateTime dateTimeMax = LocalDateTime.parse(max, formatter);
long days = ChronoUnit.DAYS.between(dateTimeMin, dateTimeMax);
long minutes = ChronoUnit.MINUTES.between(dateTimeMin, dateTimeMax);
System.out.println(days);
System.out.println(minutes);
use SimpleDateFormat to parse the date string, and do operation on Date result, you will get right value. This works well for date between '2017-02-28 23:59:59' and '2017-03-01 00:00:01'
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date1 = format.parse("2017-02-28 23:59:59");
Date date2 = format.parse("2017-03-01 00:00:01");
long time1 = date1.getTime();
long time2 = date2.getTime();
long diff = time2 - time2; // should be 2000

Display hours between 2 dates in java

i have this code, i need show only hours:min:sec, any help?
String var = "1429174464829"; (this is time in System.currentTimeMillis() )
String p = "HH:mm:ss";
SimpleDateFormat f = new SimpleDateFormat(p);
long t = var - System.currentTimeMillis();
String result = f.format(new Date(t));
in example String var, is 1 hours higher than System.currentTimeMillis()
result problem
EDIT: i obtain: result = 21:59:00
thanks
Java 8
Okay, this is a little unpleasant, but will get the job done, this is using Java 8's Time API
LocalDateTime dt1 = LocalDateTime.ofInstant(Instant.ofEpochMilli(1429174464829L), ZoneId.systemDefault());
LocalDateTime dt2 = LocalDateTime.now().plusDays(1);
System.out.println(dt1);
System.out.println(dt2);
StringJoiner sj = new StringJoiner(":");
long hours = ChronoUnit.HOURS.between(dt1, dt2);
sj.add(Long.toString(hours));
dt2 = dt2.minusHours(hours);
long mins = ChronoUnit.MINUTES.between(dt1, dt2);
sj.add(Long.toString(mins));
dt2 = dt2.minusMinutes(mins);
long secs = ChronoUnit.SECONDS.between(dt1, dt2);
sj.add(Long.toString(secs));
System.out.println(sj);
And will output something like...
2015-04-16T18:54:24.829
2015-04-17T14:10:54.281
19:16:29
Now, if I was to do something like...
LocalDateTime dt2 = LocalDateTime.now().plusDays(4);
I'd get 91:21:10 instead.
I'm hoping someone has a better solution, cause that's kind of a mess...
Joda-Time
If you can't use Java 8, then use Joda-Time
DateTime dt1 = new DateTime(1429174464829L);
DateTime dt2 = DateTime.now().plusDays(4);
System.out.println(dt1);
System.out.println(dt2);
Duration yourDuration = new Duration(dt1, dt2);
Period period = yourDuration.toPeriod();
PeriodFormatter hms = new PeriodFormatterBuilder()
.printZeroAlways()
.appendHours()
.appendSeparator(":")
.appendMinutes()
.appendSeparator(":")
.appendSeconds()
.toFormatter();
String result = hms.print(period);
System.out.println(result);
Which outputs 91:26:33
There is some time zone issue. we have to specify time zone with SimpleDateFormat. It gives result after adding time difference of your system time zone with standard UTC time zone. By default it takes your local system time zone.
String var = "1429174464829"; (this is time in System.currentTimeMillis() )
String p = "HH:mm:ss";
SimpleDateFormat f = new SimpleDateFormat(p);
f.setTimeZone(TimeZone.getTimeZone("UTC"));
long t = long.parseLong(var) - System.currentTimeMillis();
String result = f.format(new Date(t));
Well, in my experience this kind of thing is something you don't want to code yourself. Somewhere down the line you'll run into border cases like Daylight Saving Time, Leap years, etc, etc.
If you want to do this kind of thing reliably, use a time library like JodaTime (my preference)
For instance, the Period class can give you individual parts, and can be produced form a Duration by calling toPeriod().
I think you can use Jodatime for getting hours and its a good library. Hope it helps. Cheers!

java.text.ParseException: Unparseable date when trying to convert "2013-07-01T04:37:14.771468Z" into Local time

I need to convert UTC time string I get into local time using following method,
String dateCreate = "2013-07-01T04:37:14.771468Z"
DateFormat dfParse = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss'Z'");
dfParse.setTimeZone(TimeZone.getTimeZone("UTC"));
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
df.setTimeZone(TimeZone.getTimeZone("Asia/Colombo"));
java.util.Date dateTime;
dateTime = dfParse.parse(dateCreate);
String dteCreate = df.format(dateTime);
Can someone plese give me a solution for this.? :)
EDIT: Now that I've checked it supports this easily, I'd strongly recommend that you use Joda Time. Its ISO-8601 parser works fine:
String dateCreate = "2013-07-01T04:37:14.771468Z";
DateTimeFormatter formatter = ISODateTimeFormat.dateTime();
DateTime parsed = formatter.parseDateTime(dateCreate);
By default that will convert to the system default time zone, but you can change that behaviour with calls on DateTimeFormatter.
Joda Time is also a much cleaner API than the built-in one - you'll find any date/time code is easier to write and easier to read.
Look at your input data and your pattern:
String dateCreate = "2013-07-01T04:37:14.771468Z";
DateFormat dfParse = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss'Z'");
They don't match at all. You need something like:
// Don't use this directly!
DateFormat dfParse = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'");
dfParse.setTimeZone(TimeZone.getTimeZone("UTC"));
Or:
// Don't use this directly!
DateFormat dfParse = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSSX");
The latter will cope with any ISO-8601 time zone; the former restricts to UTC.
Unfortunately, the above will end up with the wrong number of milliseconds as it will take all the microseconds to be milliseconds. I don't know of a way of avoiding this in Java... you may need to trim the string first. For example:
// Remove the sub-millisecond part, assuming it's three digits:
int firstPartLength = "yyyy-MM-ddTHH:mm:ss.SSS".length();
String noMicros = dateCreate.substring(0, firstPartLength) +
dateCreate.substring(firstPartLength + 3);
// Now we've got text without micros, so create an appropriate pattern
DateFormat dfParse = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSX");
Date date = dfParse.parse(noMicros);
Alternatively, if you know it's always going to end with "Z":
int firstPartLength = "yyyy-MM-ddTHH:mm:ss.SSS".length();
String noMicros = dateCreate.substring(0, firstPartLength);
DateFormat dfParse = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS");
dfParse.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = dfParse.parse(noMicros);
This is irritating, and it would be nice to be able to tell Java to treat any digits after the dot as "fractions of a second" but I don't know of any way of doing that using SimpleDateFormat. Note that you wouldn't be able to represent the sub-millisecond value using just Date anyway.
This is xsd dateTime format. You should use javax.xml.bind.DatatypeConverter for that
Calendar c = DatatypeConverter.parseDateTime(lexicalXSDDateTime);
Note that for SmipleDateFormat S means number of milliseconds so it will parse 771468 as 771468 ms not 0.771468 sec which adds extra 771 secs to the result date
Formatting part is OK

How to format time including milliseconds

I'm trying to get a time string in the format of YYYYMMDD-HHMMSSMilliseconds in Android
Ex: 20130312-1723437520 (2013 March 12th, 17 Hour 23 Minutes 43 Seconds 7520 Milliseconds)
Time now = new Time();
now.setToNow();
String snapshotTime = now.format("yyyyMMdd-HHmmss");
First of all, above code doesn't even work properly. snapshotTime is always set to the format string itself.
Second of all, according to the Android documentation, there's no way to record milliseconds.
How can I accomplish this?
See the SimpleDateFormat class, you can format a Date object into the required format (upper-case S will give millis)
SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
Date now = new Date();
String str = fmt.format(now);
That said, using Joda Time is usually a good idea (Proguard will strip code you don't use).
You'll have to use the strftime formatting, as noted in the Android docs.
Time now = new Time();
now.setToNow();
String snapshotTime = now.format("%Y%m%d-%H%M%S");
If you really want to use milliseconds than I would recommend SimpleDateFormat.
Try getting the time as unix timestamp with milliseconds from
long currentTime = System.currentTimeMillis();
or convert your time to milliseconds:
long currentTime = now.toMillis(true);
Then you can convert this to your desired date:
Time now = new Time();
now.set(currentTime);
String snapshotTime = now.format("%Y%m%d-%H%M%S")+""+(currentTime%1000);
Didn't test it but hope it works :)
I would recommend to use this little library, it's very helpful when working with dates. Have a look at the DateTimeFormatter class.
As an alternative use Calendar and SimpleDateFormater (you'll have to adjust the format string of course, see this for explanation of the symbols)
Calendar c = new GregorianCalendar();
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy-SSSS");
String date = sdf.format(c.getTime());
You can try this:
public static String format() {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd-HHmmssSSS");
Date now = new Date();
return simpleDateFormat.format(now);
}

How to add 10 minutes to my (String) time?

I have this time:
String myTime = "14:10";
Now I want to add 10 minutes to this time, so that it would be 14:20
How can I achieve this?
Something like this
String myTime = "14:10";
SimpleDateFormat df = new SimpleDateFormat("HH:mm");
Date d = df.parse(myTime);
Calendar cal = Calendar.getInstance();
cal.setTime(d);
cal.add(Calendar.MINUTE, 10);
String newTime = df.format(cal.getTime());
As a fair warning there might be some problems if daylight savings time is involved in this 10 minute period.
I would use Joda Time, parse the time as a LocalTime, and then use
time = time.plusMinutes(10);
Short but complete program to demonstrate this:
import org.joda.time.*;
import org.joda.time.format.*;
public class Test {
public static void main(String[] args) {
DateTimeFormatter formatter = DateTimeFormat.forPattern("HH:mm");
LocalTime time = formatter.parseLocalTime("14:10");
time = time.plusMinutes(10);
System.out.println(formatter.print(time));
}
}
Note that I would definitely use Joda Time instead of java.util.Date/Calendar if you possibly can - it's a much nicer API.
Use Calendar.add(int field,int amount) method.
Java 7 Time API
DateTimeFormatter df = DateTimeFormatter.ofPattern("HH:mm");
LocalTime lt = LocalTime.parse("14:10");
System.out.println(df.format(lt.plusMinutes(10)));
You need to have it converted to a Date, where you can then add a number of seconds, and convert it back to a string.
I used the code below to add a certain time interval to the current time.
int interval = 30;
SimpleDateFormat df = new SimpleDateFormat("HH:mm");
Calendar time = Calendar.getInstance();
Log.i("Time ", String.valueOf(df.format(time.getTime())));
time.add(Calendar.MINUTE, interval);
Log.i("New Time ", String.valueOf(df.format(time.getTime())));
You have a plenty of easy approaches within above answers.
This is just another idea. You can convert it to millisecond and add the TimeZoneOffset and add / deduct the mins/hours/days etc by milliseconds.
String myTime = "14:10";
int minsToAdd = 10;
Date date = new Date();
date.setTime((((Integer.parseInt(myTime.split(":")[0]))*60 + (Integer.parseInt(myTime.split(":")[1])))+ date1.getTimezoneOffset())*60000);
System.out.println(date.getHours() + ":"+date.getMinutes());
date.setTime(date.getTime()+ minsToAdd *60000);
System.out.println(date.getHours() + ":"+date.getMinutes());
Output :
14:10
14:20
I would recommend storing the time as integers and regulate it through the division and modulo operators, once that is done convert the integers into the string format you require.

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