Help(polymorphic variables in java)

[java.cream]

Hi all,

I need help in polymorphic variables concept ,Are
there any polymorphic variables in the code belowand Explain why?

thnks..

class Square {
protected int side;
public Square (int s) {
side = s;
}
public int getSide() { return side; }
}

class Container {
protected static int num = 0 ;                  //1
protected Square aSquare;
public Container (Square s) {                 //2
           num++;
           aSquare = s;
}
public int getNum ( ) { return num; }
public void setNum ( int n ) { num = n; }
public void changeSquare ( Square s ) { aSquare = s; }
public Square getSquare ( ) { return aSquare; }
}

class TestContainer {
static public void main (String [ ] args) {
     Square s1 = new Square (4);
     Square s2 = new Square (8);
     Container con1 = new Container (s1);
     Container con2 = new Container (s2);                                      // 3

     con1.changeSquare (con2.getSquare ());                                // 4
     System.out.print("Container number " + con1.num );
     System.out.println (" Side = " + con1.getSquare ().getSide());
     System.out.print("Container number " + con2.num );
     System.out.println (" Side = " + con2.getSquare ().getSide());
}
}