How to create a single expression displaying time difference between two Date's as years, months, days, hours, minutes, seconds

Question

How can I create a single jasper report JRExpression that visualize the difference between two java.util.Date in format yy year(s) month(s) dd day(s), hh hour(s), mm minute(s), ss second(s)

java.util.Date startDate
java.util.Date endDate

A JRExpression is a single line where variable declaration is not allowed, however you may use conditional statements using syntax boolean ? yes:no, for you who are not familiar imagine one line of System.out.println();

Example of desired output (if you have a nice solution remove description of unit when not present and consider singular/plural but this is not necessary if it's a serie of if statements):

2 years, 8 months, 12 days, 2 hours, 53 minutes, 10 s

1 hour, 1 minute

both Feb 2- Mar 4 and Mar 4 - April 6 are "1 month, 2 days", daylight savings however can be ignored - thanks @Affe

Additional requirements:

Only jasper report dependencies may be used (joda is not included).
Preferable jdk 1.7 or less (1.8 is accepted if this is only solution)

There is no need to format the answer as jasper report expression it can be a simple System.out.println code (I'm happy to edit your answer later to also add the jasper report expression code). Example

((endDate.getTime()-startDate.getTime()) / (60 * 60 * 1000)) % 24 + " hour(s), " +  
((endDate.getTime()-startDate.getTime()) / (60 * 1000)) % 60 + " minute(s)"

What have I tried:

I answer multiple question in the jasper report section of SO, and this question is common in report generation. I would prefer a good answer from the java section that I can link rather then passing my code on this issue (that I would only know to solve partially as example)

This is an example on question in jasper-report: Calculating Time and Date difference

Some reference code:

Calculate date/time difference in java

How to find the duration of difference between two dates in java?

For you that are familiar to jasper report I don't want to use the variable declaration since this would invalidate the solution if user need to use it on parameters.

Tangentially how do you define a month there? Are both Feb 2- Mar 4 and Mar 4 - April 6 "One Month Two Days"? — Affe, Jan 07 '16 at 21:39
Nice comment, I would prefer a solution like that, seems correct, this is what a client/user would expect — Petter Friberg, Jan 07 '16 at 21:42
I don't see how you can achieve this in one line, simply because the JDK versions of the required APIs do not use a 'Fluent' style that allows them to be utilized in a one-line fashion. Can't you just put the code in a static method and drop the class file in the /lib folder on the jasper server? — Affe, Jan 07 '16 at 21:45
@Affe No if user (poster on so) need's to install additional libraries in ireport, jasper studio ecc this will start a never ending comment thread ... but I have feeling you can... note you can do new GregorianCalendar ecc how many time you like and I had a vague hope that someone knows about the commons library already include, no method inside of these?? — Petter Friberg, Jan 07 '16 at 21:51
Note, after @Affe comment I have lowered the requirements 1.8 is allowed, if this is only solution. — Petter Friberg, Jan 07 '16 at 22:32
The problem with the Calendar API is you can't even do simple naive things like `new GregorianCalendar(starDate).add(DAYS, (endDate-startDate/(TimeUnit.DAYS.toMillis(1)).get(MONTH)` (ignoring potential issues that has with daylight savings) because the return type of `add` is `void` not `Calendar` so you need a second "line" of code to do `get(MONTH)` on. — Affe, Jan 07 '16 at 23:02

score 2 · Accepted Answer · edited May 23 '17 at 12:00

The Calendar API cannot be directly be used for this problem: every operation would require multiple lines since the interesting methods are void returning and can't be chained.

This is a very big stretch, but, as listed in the dependencies of JasperReports, there is org.codehaus.castor:castor-xml:1.3.3 which depends itself on commons-lang:commons-lang:2.6. We therefore can make use of the DurationFormatUtils.formatPeriod(startMillis, endMillis, format) method, which is present in commons-lang. The format String to use here would be

"y' years 'M' months 'd' days 'H' hours 'm' minutes 's' seconds'"

which would print the wanted String. Care must still be taken: this will include 0s (like "0 months") and will also have incorrect pluralization (like "1 months").

We can use the regular expression "(?<!\\d)0 (\\w+) ?" to remove all the 0s for the String. This regex matches any 0, not preceded by a digit (we don't want to match 10 for example), followed by one or more word characters and optionally followed by a space.
Then, we can use the regular expression "(?<!\\d)1 (\\w+)s" to match every occurence of "1 ...s" and replace it with "1 ..." to have proper pluralization. This regular expression matches any 1, not preceded by a digit, followed by one or more word characters (captured in a group) ending with an s; it would be replaced with "1 $1", i.e. 1 followed by the value captured.

Example:

System.out.println(
    org.apache.commons.lang.time.DurationFormatUtils.formatPeriod(
            startDate.getTime(), 
            endDate.getTime(), 
            "y' years 'M' months 'd' days 'H' hours 'm' minutes 's' seconds'"
    )
    .replaceAll("(?<!\\d)0 (\\w+) ?", "")
    .replaceAll("(?<!\\d)1 (\\w+)s", "1 $1")
);

All this can be done with Java 7 or lower.

In a JasperReports, this would be an example:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.2.1.final using JasperReports Library version 6.2.1 -->
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports jasperreports.sourceforge.net/…" name="Blank_A4" pageWidth="595" pageHeight="842" whenNoDataType="AllSectionsNoDetail" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="f067f2c4-395f-4669-9fda-4fe81cc59227">
  <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
  <parameter name="dateStart" class="java.util.Date" isForPrompting="false">
    <defaultValueExpression><![CDATA[new java.util.Date(1)]]></defaultValueExpression>
  </parameter>
  <parameter name="dateEnd" class="java.util.Date" isForPrompting="false">
    <defaultValueExpression><![CDATA[new java.util.Date()]]></defaultValueExpression>
  </parameter>
  <queryString><![CDATA[]]></queryString>
  <title>
    <band height="43" splitType="Stretch">
      <textField>
        <reportElement x="0" y="0" width="560" height="30" uuid="cc03531c-2983-4f9a-9619-2826ed92760e"/>
        <textFieldExpression><![CDATA[org.apache.commons.lang.time.DurationFormatUtils.formatPeriod($P{dateStart}.getTime(),$P{dateEnd}.getTime(),"y' years 'M' months 'd' days 'H' hours 'm' minutes 's' seconds'").replaceAll("(?<!\\d)0 (\\w+) ?", "").replaceAll("(?<!\\d)1 (\\w+)s", "1 $1")]]></textFieldExpression>
      </textField>
    </band>
  </title>
</jasperReport>

With the output being:

If the above looks too fragile (because of the explicit dependency towards commons-lang that could not be there for all JasperReports version), there is another possible solution using the Java Time API introduced in Java 8.

This is horrible (I don't think there is a simpler way), but the output is exactly the same as above, where start and end are both LocalDateTime objects:

System.out.println((
    ChronoUnit.YEARS.between(start, end) + " years " +
    ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end) + " months " +
    ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end) + " days " +
    ChronoUnit.HOURS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)), end) + " hours " +
    ChronoUnit.MINUTES.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)).plusHours(ChronoUnit.HOURS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)), end)), end) + " minutes " +
    ChronoUnit.SECONDS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)).plusHours(ChronoUnit.HOURS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)), end)).plusMinutes(ChronoUnit.MINUTES.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)).plusHours(ChronoUnit.HOURS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)).plusDays(ChronoUnit.DAYS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)).plusMonths(ChronoUnit.MONTHS.between(start.plusYears(ChronoUnit.YEARS.between(start, end)), end)), end)), end)), end)), end) + " seconds"
    )
    .replaceAll("(?<!\\d)0 (\\w+) ?", "")
    .replaceAll("(?<!\\d)1 (\\w+)s", "1 $1")
);

How to create a single expression displaying time difference between two Date's as years, months, days, hours, minutes, seconds

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