How to Implement Crosstab Column Group Custom Sorting

Issue Description

I created a JRXML report with Crosstab. One of group column based on a String field which returns

period values like 'Aug 2017', 'Jan 2017' etc.

By default, the column sorted alphabetically.

How can I change it to sort the values as Date type, Jan-2017, Feb-2017 an so on?

Resolution

Solution requires creating a custom Java class that implements Comparator interface.

That class converts strings with values like 'Apr 2017' into a Date value and then compare them.

In order to use custom comparator in Crosstab, report hidden parameter required to call the custom class:

    <parameter name="myOrder" class="com.sample.DateComparator" isForPrompting="false">

        <defaultValueExpression><![CDATA[new DateComparator()]]></defaultValueExpression>

    </parameter>

Then, the parameter is used in crosstab column group comparator expression:

                <columnGroup name="period" height="20">

                    <bucket class="java.lang.String">

                        <bucketExpression><![CDATA[$F{period}]]></bucketExpression>

                        <comparatorExpression><![CDATA[$P{myOrder}]]></comparatorExpression>

                   </bucket>

        ............

        </columnGroup>

The custom class should be specified in Import property of the report:

    <import value="com.sample.*"/>

Attached are:

 - custom comparator Java code

 - compiled package

 - JRXML report

Ref. Case 01466303

datecomparator_0.java

datecomparator.jar

support_period_sortorder.jrxml