Java Programming

Hello I'm having some troubles dealing with 'java.sql.Date' I'm working with express edition database and I have three classes(different packages)

1.Mapper
2.Objects Class
3.ConsoleTest

I need to get an arraylist of objects, some of which contain dates, but when try to do it I get this exception
"java.sql.SQLException: Invalid column type: getDate not implemented for class oracle.jdbc.driver.T4CNumberAccessor"

Do you have any idea how I can implement the getDate method for this T4CNumberAccessor

Here are the methods that I'm using
1.Mapper

public ArrayList<Object> getAllTaskAuctions(Connection con)
{
ArrayList<Object> l1 = new ArrayList<Object>();
String SQLString1 = "select * from taskauction natural join tasks";
PreparedStatement statement=null;
try
{
//=== get taskauctions natural join tasks
statement = con.prepareStatement(SQLString1);
ResultSet rs = statement.executeQuery();
while(rs.next())
{
l1.add(new TaskAuction(rs.getInt(1), rs.getInt(2), rs.getInt(3),
rs.getDate(4), rs.getDate(5), rs.getInt(6)));
l1.add(new Task(rs.getInt(1), rs.getInt(2), rs.getString(3),
rs.getString(4), rs.getString(5), rs.getString(6), rs.getInt(7)));
}
}
catch (Exception exc)
{
System.out.println("Fail in TaskAuctionMapper - getAllTaskAuctions");
System.out.println(exc);
}

return l1;
}

2.ConsoleTest class

Connection con;
public Connection getConnection(){
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:XE", "Project", "123" );

//username/password@[/]host[:port][service_name]
}
catch (Exception e)
{ System.out.println("fail in getConnection()");
System.out.println(e); }
return con;
}

public static void main(String[] args) {



ConsoleTest ct = new ConsoleTest();
TaskAuctionMapper tam1 = new TaskAuctionMapper();
ArrayList<Object> alt1 = tam1.getAllTaskAuctions(ct.getConnection());
Iterator<Object> itr1 = alt1.iterator();
while (itr1.hasNext())
{
TaskAuction taskauct = (TaskAuction) itr1.next();
//Problem, exception traced to TaskAuctionMapper
System.out.println(
"Task ID: " + taskauct.getTaskid()+ ", "+
"StartDate: "+ taskauct.getStartdate()+", "+
"User ID: " + taskauct.getUserid());
}


}