Re: Generics question

My HistoryTableModel starts off like this:

public abstract class HistoryTableModel
   extends AbstractTableModel {

  // I've tried various things here, this is just
  // the latest.
  protected ContinuousHistory<? extends History> history;

  public abstract Object getValueAt(int row, int col);

  // This is just an example method.
  public final int getRowCount() {
    return history.getHistoryData().size();
  }

  . . .
}

Now here's one of the concrete subclasses:

public class TitleTableModel extends HistoryTableModel {
  public TitleTableModel(
    ContinuousHistory<? extends History> history)
  {
    this.history = (ContinuousHistory<TermTypeHistory>)
                    history;
  }

  public Object getValueAt(int row, int col) {
    TitleHistory th = history.get(row); // COMPILE ERROR

    // etc.
  }

  . . .
}

This implementation won't compile, saying:
  Type mismatch: cannot convert from capture-of ? extends
  History to TitleHistory
at the spot I indicated above.

What's the right way to declare "history" in class
HistoryTableModel so that it will be a
ContinuousHistory<some class which extends History>,
and the right way to declare the subclass to use it as
a ContinuousHistory<TermTypeHistory> (or whatever other
concrete class)? I've tried a dozen or so different ways,
and I can't find one that works.