Validation in TableViewEditor

[Vicente de Rivera III]

I'm using TableViewEditor a lot and I noticed in my code that for all
TableViewEditor, I have
   tableViewRowEditor.getRowEditorListeners().add(new
TableView.RowEditorListener.Adapter() {
            private boolean shown = false;
            private boolean invalid = false;
            @Override
            public Vote previewSaveChanges(RowEditor rowEditor, TableView
tableView, int rowIndex, int columnIndex, Dictionary<String, Object>
changes) {
                invalid = usernameTI.getText().isEmpty() ||
passwordTI.getText().isEmpty();
                String errorMsg = (usernameTI.getText().isEmpty() ?
"Username" : "") +
                                  (passwordTI.getText().isEmpty() ?
"Password" : "") +
                                  " cannot be empty";
                if (invalid) {
                    if (!shown) {
                        Prompt.prompt(MessageType.ERROR, errorMsg, null,
main.getWindow(),
                                new SheetCloseListener() {

                                    public void sheetClosed(Sheet sheet) {
                                        shown = false;
                                    }
                                });
                        shown = true;
                    }
                    return Vote.DENY;
                }
                return Vote.APPROVE;
            }});

I'm thinking maybe I could just add validation to TableViewEditor. Something
like
      tableViewRowEditor.getValidators().add(
org.apache.pivot.wtk.text.validation.Validator )