VECTOR: Can't Locate Where to Specify Content Type

Question

Hi all. I'm confused with warning from compiler. I'm specifying methods for swing TableModel using vector data and it always shows me unchecked call to set as a member of raw type (method setValueAt). I just have no idea how to cast type there. The code is below:
import java.util.Vector;
public class SSCCE {
public static void main(String[] args){
    new dk_MF();
class dk_MF{
dk_MF(){ constructTable();  }
public void constructTable(){
  Vector<Vector> bigvec = getTabData();
  Vector smallvec = (Vector) bigvec.elementAt(0).clone();
  bigvec.remove(0);
  Model MM = new Model(bigvec,smallvec);
  System.out.println(MM.getValueAt(0,0)); }
public Vector<Vector> getTabData(){
  Vector<Vector> bv = new Vector<Vector>();
  Vector<String> sv = new Vector<String>();
  sv.add("one"); sv.add("two");
  bv.add((Vector)sv.clone());
  bv.add((Vector)sv.clone());
  sv.clear();
  return bv; }
class Model {
  private Vector columnNames = null;
  private Vector data = null;
  public Object getValueAt(int row, int col){
   return ((Vector) data.elementAt(row)).elementAt(col); }
  public void setValueAt(Object value, int row, int col) {
   ((Vector) data.elementAt(row)).set(col, value);  }
  public void createNewTable(Vector b, Vector s) {
   data = (Vector) b.clone();
   columnNames = (Vector) s.clone();  }
  Model(Vector big, Vector small) {
   createNewTable(big,small);
}

Answer 1

Thanks for the tip on casting problem! But now I'm back to the starting point. OK, I have a Vector of Vectors of Arbitrary Data: Vector<Vector<?>>. I've done all this description in the code (below). But this cursed "unchecked call to set" remains.
What, actually, this "unchecked call" means? Why casting ((Vector) data.elementAt(row)) at getValueAt does not get a warning?
P.S. I've tryed to put Vector<?> (caused error) and Vector<Object> (warning) in setValueAt, but this did not help!
import java.util.Vector;
public class SSCCE {
public static void main(String[] args){
    new dk_MF();
class dk_MF{
dk_MF(){ constructTable();  }
public void constructTable(){
  Vector<Vector<?>> bigvec = getTabData();
  Vector smallvec = (Vector) bigvec.elementAt(0).clone();
  bigvec.remove(0);
  Model MM = new Model(bigvec,smallvec);
  System.out.println(MM.getValueAt(0,0)); }
public Vector<Vector<?>> getTabData(){
  Vector<Vector<?>> bv = new Vector<Vector<?>>();
  Vector<String> sv = new Vector<String>();
  sv.add("one"); sv.add("two");
  bv.add(new Vector<String>(sv));
  bv.add(new Vector<String>(sv));
  sv.clear();
  return bv; }
class Model {
  private Vector columnNames = null;
  private Vector data = null;
  public Object getValueAt(int row, int col){
   return ((Vector) data.elementAt(row)).elementAt(col); }
  public void setValueAt(Object value, int row, int col) {
   ((Vector) data.elementAt(row)).set(col, value);  }
  public void createNewTable(Vector b, Vector s) {
   data = (Vector) b.clone();
   columnNames = (Vector) s.clone();  }
  Model(Vector big, Vector small) {
   createNewTable(big,small);
}