java - ireport iterating through data Collection and accesing fields -

i want create simple report jasper ireport. don't know how iterate thought object c fields. purpose created sub report. example of classes:

public class d {     private a;     private b b;     private arraylist<c> c;     //getters setters }  public class c {    int id;        string name;    // getters setters } 

in main report declared :

<subreport> ..... <datasourceexpression><![cdata[new net.sf.jasperreports.engine.data.jrbeancollectiondatasource($f{c})]]></datasourceexpression> <subreportexpression><![cdata["c:\\path\\report1_subreport2.jasper"]]></subreportexpression> </subreport> 

in sub report :

<field name="c" class="java.util.collections"/> 

my question: how access fields of class c?

i tried change class java.util.collections c, create fields names of c nothing helps.

when define fields, follows

<field name="c.id" class="java.lang.string"/>

<field name="c.name" class="java.lang.string"/>

where c object and, id , name fields of class c. make changes in class in code.