Action Point Of Sale Code

package cell;
public abstract class CellBase
{
 public Object clone()
 {
  return null;
  }
 public abstract Object go(byte x, short y);
 public abstract void so(byte x, short y, Object o);
 public abstract short max();
 abstract void ramDelete(short y);
 public float af(byte col, short row)
 {
  try
  {
   return ((Float)go(col, row)).floatValue();
   }
  catch (Exception e)
  {
   return 0;
   }
  }
 String mh(byte col, short row)
 {
  for (short i = row; i >= 0; i--)
  {
   String s = go(col, i) + "";
   if (!s.trim().equals("")) return s;
   }
  return null;
  }
 }