Exception "not implemented for class oracle.jdbc.driver.T4CNumberAccessor"

[jeata]

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"

Here are the classes
1.Mapper(method to get the arraylist)

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.Objects Classes
TaskAuction

public class TaskAuction {
	
	int winnerid;
	int taskid;
	int bidid;
	Date startdate;
	Date finishdate;
	int userid; 
	
	public TaskAuction(int wid, int tid, int bid, Date sd, Date fd, int toid)
	{
		winnerid = wid;
		taskid = tid;
		bidid = bid;
		startdate = sd;
		finishdate = fd;
		userid = toid;
	}
	
	//---AUTOGENERATED GETTERS AND SETTERS---//

	public int getWinnerid() {
		return winnerid;
	}

	public void setWinnerid(int winnerid) {
		this.winnerid = winnerid;
	}

	public int getTaskid() {
		return taskid;
	}

	public void setTaskid(int taskid) {
		this.taskid = taskid;
	}

	public int getBidid() {
		return bidid;
	}

	public void setBidid(int bidid) {
		this.bidid = bidid;
	}

	public Date getStartdate() {
		return startdate;
	}

	public void setStartdate(Date startdate) {
		this.startdate = startdate;
	}

	public Date getFinishdate() {
		return finishdate;
	}

	public void setFinishdate(Date finishdate) {
		this.finishdate = finishdate;
	}

	public int getUserid() {
		return userid;
	}

	public void setUserid(int userid) {
		this.userid = userid;
	}
	
	

}

Task

public class Task {
	
	int taskid;      
    int userid;      
    String title;       
    String description; 
    String progress; 
    String planprogress; 
    int price; 
    
     public Task(int tid, int uid, String tit, String desc, 
    		String prg, String plnprg, int pr)
    {
    	taskid=tid;
    	userid=uid;
    	title=tit;
    	description=desc;
    	progress=prg;
    	planprogress=plnprg;
    	price=pr;
    }
     
   //======AUTOGENERATED GETTERS AND SETTERS======//

	public int getTaskid() {
		return taskid;
	}

	public void setTaskid(int taskid) {
		this.taskid = taskid;
	}

	public int getUserid() {
		return userid;
	}

	public void setUserid(int userid) {
		this.userid = userid;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public String getDescription() {
		return description;
	}

	public void setDescription(String description) {
		this.description = description;
	}

	public String getProgress() {
		return progress;
	}

	public void setProgress(String progress) {
		this.progress = progress;
	}

	public String getPlanprogress() {
		return planprogress;
	}

	public void setPlanprogress(String planprogress) {
		this.planprogress = planprogress;
	}

	public int getPrice() {
		return price;
	}

	public void setPrice(int price) {
		this.price = price;
	}
     
     
     

}

3.ConsoleTest

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());
        }
        

	}