Display data in TableView from ArrayList of Object

I would to display data from an arrayList into a TableView but I have some problem with the mechanism of ''setCellValueFactory''. The code is this:

public class Example implements Comparable<Example>{
private List<Object> example=new ArrayList<Object>();

public void add(Object o){
    example.add(o);
}

public Object get(int i){
    return example.get(i);
}
public int compareTo(Example ex) {

    int i=0;
    for(Object o:ex.example){
        if(!o.equals(this.example.get(i)))
            return ((Comparable)o).compareTo(example.get(i));
        i++;
    }
    return 0;
}
public String toString(){
    String str="";
    for(Object o:example)
        str+=o.toString()+ " ";
    return str;
}   

}

public void start(Stage stage) throws SQLException, DatabaseConnectionException { 
  ....
  ....
  ....
  ....
  ....
  ....
   tab.setMinWidth(700);
   tables.getSelectionModel().selectedItemProperty().addListener(
       (ov,old_val,new_val)->{
           tab.getColumns().clear();
           try {
               List<Example> data = new ArrayList<Example>();
               TableData tableData = new TableData(new DbAccess((String)dataBases.getValue()));
               data = tableData.getDistinctTransazioni(new_val);
               TableSchema tableSchema = new TableSchema(new DbAccess((String)dataBases.getValue()),new_val);
               for (int i=0;i<tableSchema.getNumberOfAttributes();i++) {
                    TableColumn column = new TableColumn(tableSchema.getColumn(i).getColumnName());
                    tab.getColumns().add(column);   
               }

               ObservableList<Example> values = FXCollections.
                        observableArrayList(data);
               tab.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY); 
               tab.setItems(values);

           } catch (SQLException e1) {
               e1.printStackTrace();
           } catch (DatabaseConnectionException e1) {
               e1.printStackTrace();
           } catch (EmptySetException e1) {
               e1.printStackTrace();
           }
       }
   );

In the method : column.setCellValueFactory(new PropertyValueFactory<>("Here what I put?")).- I don't have a property but I have an arrayList of Object in class Example.