reversing dataset order for chart

[jkemper]

I have a requirement to display a report with the data in DESC order with a bar chart that displays the data in ASC order.

 

I would like to do something like this but Im not sure where I would declare this expression.

 

JRDataSource newDataSource = java.util.Collections.reverse($P{REPORT_DATA_SOURCE})

 

Is this the right way to go, or is it possible to reverse the order of the dataset inside a JRChartCustomizer?

 

thx

[jkemper]

i figured out a way to do this.

 

1. split the chart out into a subreport that takes a datasource of new ...JRCollectionDataSource($V{reportData})

2. put dataset into map of params and declare the parameter $P{reportData}

3. create a variable $V{reportData} that has an expression of com.mycompany.ListUtil.reverseList($P{reportData})

4. create class ListUtil -- i couldn't find anything in the jdk or apache commons that took a list reversed it and returned a new list which is seems most jasper expressions require a return value. So i created this wrapper util.

Code:

public class ListUtil {
   public static List reverseList(List listToReverse) {
      Collections.reverse(listToReverse);
      return listToReverse;
   }
}