Compiler warning with Collections.sort() method

Question

Hi,
I am sorting a Vector that contains CardTiles objects. CardTiles is a class that extends JButton and implements Comparable. The code works fine but i get the following warning after compilation.
Note: DeckOfCards.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
After compiling with -Xlint, i get the following warning;
DeckOfCards.java:173: warning: [unchecked] unchecked method invocation: <T>sort(java.util.List<T>) in java.util.Collections is applied to (java.util.Vector<CardTiles>)
Collections.sort(handTwo);
^
What could be the problem? Is Collections.sort() only intended for Collections of type List?
Many thanks!

Answer 1

Hi Jverd, my handTwo Vector was declared as follows;
Vector<CardTiles> handTwo = new Vector<CardTiles>();
The CardTiles Source code is as follows;
import javax.swing.*;
import java.util.*;
public class CardTiles extends JButton implements Comparable{
     static String typeOfSort = "face";
     public static final long serialVersionUID = 24362462L;
     int i=1;
     public ImageIcon myIcon;
     public Card myCard;
     public CardTiles(ImageIcon i, Card c){
          super(i);
          myIcon = i;
          myCard = c;
     public int compareTo(Object o){
          CardTiles compare = (CardTiles)o;
          if(typeOfSort.equals("face")){
               Integer ref1 = new Integer(this.myCard.getFaceValue());
               Integer ref2 = new Integer(compare.myCard.getFaceValue());
               return ref1.compareTo(ref2);
          }else{
               if(this.myCard.getFaceValue() > 9 || compare.myCard.getFaceValue() >9){
                    if(this.myCard.getFaceValue() > 9 && compare.myCard.getFaceValue() >9){
                         String ref1 = this.myCard.getSuit().substring(0,(this.myCard.getSuit().length()-1));
                         String ref2 = compare.myCard.getSuit().substring(0,(compare.myCard.getSuit().length()-1));
                         return ref1.compareTo(ref2);
                    }else{
                         if(this.myCard.getFaceValue() > 9 || compare.myCard.getFaceValue() >9){
                              String ref1 = this.myCard.getSuit().substring(0,(this.myCard.getSuit().length()-1));
                              String ref2 = compare.myCard.getSuit() + Integer.toString(compare.myCard.getFaceValue());
                              return ref1.compareTo(ref2);
                         }else{
                              String ref1 = this.myCard.getSuit() + Integer.toString(this.myCard.getFaceValue());
                              String ref2 = compare.myCard.getSuit().substring(0,(compare.myCard.getSuit().length()-1));
                              return ref1.compareTo(ref2);
               }else{
                    String ref1 = this.myCard.getSuit() + Integer.toString(this.myCard.getFaceValue());
                    String ref2 = compare.myCard.getSuit() + Integer.toString(compare.myCard.getFaceValue());
                    return ref1.compareTo(ref2);
     public String toString(){
          return ( myCard.toString() + " with fileName " + myIcon.toString());
}What could be wrong?
Many thanks!