Generics I cant get this thing going?

Question

I have a Class declaration:
public class DataContainer<T extends Row>{
public doSomething(T t){
Row has four subclasses - DirtyRow, PostDirtyRow, PreDirtyRow, FilterDirtyRow
How can I now invoke the doSomething method of the DataContainer with the subtype.
Something like
DataContainer dc = new DataContainer();
DirtyRow dr = new DirtyRow();
dc.doSomething(dr);
The freaking compiler does not let me do this ... crying out loud how can we solve this generics with subtype problem.
Regards and thanx in advance.

Answer 1

DataContainer contain specific types of Rows which
gets saved in a collection. As such, we want to
ensure that a specific instance of DataContainer will
only contain that type (DC has an add(T t) method).
The question basically is, how can I call the add
method passing the super class Row as an argument to
a DataContainer whose type is not known. Consider
the following :
public void addRow(DataContainer<? extends Row> dc,
Row row){
dc.add(row);
This does not work, of course, because of the
wildcard.Is this what you want?
   public <T extends Row> void addRow(DataContainer<T> dc, T row){
      dc.add(row);
   }