/**
 Demonstrates where the clone method works,
 but copy constructors do not.
*/
public class CopyingDemo
{

    public static void main(String[] args)
    {
        Sale[] a = new Sale[2];
        a[0] = new Sale("atomic coffee mug", 130.00);
        a[1] = new DiscountSale("invisible paint", 5.00, 10);
        int i;

        Sale[] b = badCopy(a);

        System.out.println("With copy constructors:");
        for (i = 0; i < a.length; i++)
        {
            System.out.println("a[" + i + "] = " + a[i]);
            System.out.println("b[" + i + "] = " + b[i]);
            System.out.println();
        }
        System.out.println();

        b = goodCopy(a);

        System.out.println("With clone method:");
        for (i = 0; i < a.length; i++)
        {
            System.out.println("a[" + i + "] = " + a[i]);
            System.out.println("b[" + i + "] = " + b[i]);
            System.out.println();
        }

    }
    
    /**
     Supposedly returns a safe copy of a. That is, if b is the
     array returned, then b[i] is supposedly an independent copy of a[1].
    */
    public static Sale[] badCopy(Sale[] a)
    {
        Sale[] b = new Sale[a.length];
        for (int i = 0; i < a.length; i++)
              b[i] = new Sale(a[i]);//Problem here!
        return b;
    }

    /**
     Returns a safe copy of a.That is, if b is the
     array returned, then b[i] is an independent copy of a[1].
    */
    public static Sale[] goodCopy(Sale[] a)
    {
        Sale[] b = new Sale[a.length];
        for (int i = 0; i < a.length; i++)
              b[i] = (Sale)(a[i].clone( ));
        return b;
    }
}