Add sub report to main report in JasperReport - jasper-reports

Question

I have a Report that shows its items as it should.
Now i need to add 3 sub reports to the main one.
For this i used iReports.
My question is, how do i pass the list of items to the sub reports ???
I found some tutorials but in those cases the sub reports's data is inside of the first reports.
In my case, i have a report with 4 detail band, 3 of this with a sub report.
My code:
JRBeanCollectionDataSource beanCollection = new JRBeanCollectionDataSource(report.getList());
jasperPrint = JasperFillManager.fillReport("C:\\Users\\Desktop\\Report.jasper", new HashMap(), beanCollection) ;
HttpServletResponse http = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse();
http.addHeader("Content-disposition", "attachment; filename=report.pdf");
ServletOutputStream stream = http.getOutputStream();
JasperExportManager.exportReportToPdfStream(jasperPrint, stream);
I am using jsf 2.0.
ps: i saw i can create 4 jasperPrint, and add each page to the main report but i would like to know if its possible what i looking for.
Regards.

Answer 1

Suppose your datasource has the following structure
public class MyPOJO{
private List<POJOSubData1> sub1;
private List<POJOSubData2> sub2;
private List<POJOSubData3> sub3;
//getters & setters
...
}
You can pass the desired datasource to your subreports by specifying the following to the subreport's properties
Connection type : Use a datasource expression
Data Source Expression : $F{sub1} //or sub2 or sub3
The Field Class of sub1 should be List.
Also, you dont need to put isolate 1 subreport to 1 detail band, you can put all the subreports in one detail band.

Answer 2

If you are using Ireport to create reports then open main report in Ireport and selelect Subreport and go to property section of the report, click on "Parameters" property and click on "Copy from master" tab, from there you can select the parameters which you want to pass to the sun report.

Answer 3

what i finally did :
for(JRPrintPage p : jasperPrint1.getPages()){
jasperPrint.addPage(p);
}
where jasperPrint is the main report and jasperPrint1 is the subreport(that is a report it self). On this way, i can pass the list of items to all the reports normally.
JRBeanCollectionDataSource beanCollection1 = new JRBeanCollectionDataSource(report.getSections().get(1).getRowsReports());
JasperPrint jasperPrint1 = JasperFillManager.fillReport("C:\\Users\\Desktop\\Meeting.jasper", new HashMap(), beanCollection1) ;