iReport : How to process a parameter whose expression class = List and inside that list is another list?

Question

I have a parameter whose expression class is a List. Inside that List is another list so the data looks something like this.

Class Bean{

String property1
St         


        

Answer 1

There are multiple solutions to achieve what you need.

1. Create flat structure of your datasource, as example a List of Map<String,Object>, looping your Bean, BeanDetails example

   List<Map<String,Object>> mapList = new ArrayList<Map<String,Object>>();
   for(Bean bean : yourBeans){
     Map<String,Object> map = new HashMap<String,Object>();
     map.put("col1", bean.getProperty1());
     map.put("col2", bean.getProperty2());
     map.put("col3", bean.getProperty3());
     boolean first = true;
     if (bean.getBeanDetails()==null|| bean.getBeanDetails().size()==0){
       mapList.add(map);
     }else{
      for (BeanDetails bd:bean.getBeanDetails()){
        if (!first){
            map = new HashMap<String,Object>();
            map."col1", "");//or use printWhenExpression != null in jrxml
            ....
        }else{
           first = false;
        }
        map.put("col4",bd.getDet1());
        ....
        mapList.add(map);
     }
    }
   }
   //This now becomes your datasource
   JRMapArrayDataSource datasource = new JRMapArrayDataSource(mapList);
   

2. Use subreport include a subreport spanning col4 to col6, setup field Bean in main report

   <field name="_THIS" class="com.your.package.Bean"/>
   

   and pass as datasource to the subreport

   <dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource($F{_THIS}.getBeanDetails())]]></dataSourceExpression>
   

3. Create you own JRDataSource (I will not submit the whole class, but only some hints on how this can be done, creating a new class implementing JRDataSource)

   JRDataSource myDatasource = new JRDataSource() {
       //TODO: keep controll of you list of Beans, current Bean and current BeanDetails, using pointers.
       @Override
       public boolean next() throws JRException {
        //TODO: Implement if there are still records, move to next Bean or BeanDetails
        boolean existsRecords = false;
        return existsRecords;
       }
   
       @Override
       public Object getFieldValue(JRField field) throws JRException {
          String name = field.getName();
          //TODO: On the basis of your pointer, current Bean and current BeanDetails, return the value requested.
          return null;
       }
   };
   

Make your choice and have fun!