program menara hanoi

I'm having a little trouble with a reference to a variable created from a static method.

public class Main {

static ArrayList rings = new ArrayList();

/** Creates a new instance of Main */
public Main() {

}

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
initTowers();
initRings(Integer.parseInt(JOptionPane.showInputDialog("Number of rings:")));
solve();
}

public static void initTowers(){
Tower src = new Tower(1);
Tower aux = new Tower(2);
Tower des = new Tower(3);
}

public static void initRings(int numRings){
for(int i=1; i<= numRings; i++){
rings.add(new Ring(i));
}

for(int i=numRings; i>= 1; i--){
((Ring)(rings.get(i))).moveTo(src);
}
}

public static void solve(){

}
}

The error is on this line:

((Ring)(rings.get(i))).moveTo(src);