How to format java.time.LocalDateTime and java.time.LocalDate with pattern?

Question

In the following snipped the property $F is of class java.time.LocalDateTime or java.time.LocalDate.

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[$F{theLocalDateTime}]]></textFieldExpression>
</textField>

How can I format this property with textField pattern in jasper reports?

Answer 1

To use the pattern attribute in current version of jasper-report for Date/Time object you need a java.util.Date class or one of it's subclasses.

The solution is to convert java.time.LocalDate and java.time.LocalDateTime

Converting to java.util.Date

from java.time.LocalDate

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.util.Date.from($F{theLocalDate}.atStartOfDay(java.time.ZoneId.systemDefault()).toInstant())]]></textFieldExpression>
</textField>

from java.time.LocalDateTime

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.util.Date.from($F{theLocalDateTime}.atZone(java.time.ZoneId.systemDefault()).toInstant())]]></textFieldExpression>
</textField>

Converting to java.sql.Timestamp

from java.time.LocalDate

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.sql.Timestamp.valueOf($F{theLocalDate}.atStartOfDay())]]></textFieldExpression>
</textField>

from java.time.LocalDateTime

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.sql.Timestamp.valueOf($F{theLocalDateTime})]]></textFieldExpression>
</textField>

Note: Applying pattern is always preferable solution, specially when exporting to excel since correct class will be passed to poi (hence excel will recognize column as a date and apply same formatting as in pattern)

Answer 2

As java.time module is kind of complex and verbose, I usually create some variables which holds the compiled DateTimeFormatter for further use.

I want my reports to adapt to any Locale, so I don't use string literals for formatting.

I am using the report Locale, but you can choose your Locale with java.util.Locale.forLanguageTag("en-US"), for example.

You can also change the java.time.format.FormatStyle if needed

LocalDate formatter:

    <variable name="dateFormatter" class="java.time.format.DateTimeFormatter">
        <variableExpression><![CDATA[java.time.format.DateTimeFormatter
  .ofLocalizedDate(java.time.format.FormatStyle.SHORT)
  .withLocale($P{REPORT_LOCALE})
  .withChronology(java.time.chrono.Chronology.ofLocale($P{REPORT_LOCALE}))]]></variableExpression>
    </variable>

LocalDateTime formatter:

    <variable name="dateTimeFormatter" class="java.time.format.DateTimeFormatter">
        <variableExpression><![CDATA[java.time.format.DateTimeFormatter
  .ofLocalizedDateTime(java.time.format.FormatStyle.SHORT)
  .withLocale($P{REPORT_LOCALE})
  .withChronology(java.time.chrono.Chronology.ofLocale($P{REPORT_LOCALE}))]]></variableExpression>
    </variable>

Now I can format a LocalDate field this way:

$F{localDateField}.format($V{dateFormatter})

And a LocalDateTime field this way:

$F{localDateTimeField}.format($V{dateTimeFormatter})