Supermarket operation support system - Software Development Case Studies in Java - page 378

return reply.substring(Const.ERROR.length());
}
}
// return the price of a product given the code
public double getPrice( long item) throws Exception{
String reply # sendMessage(Const.GET_PRICE ! " "
! item);
if (reply.startsWith(Const.OK)
return Double.parseDouble(reply.
substring(Const.OK.length()));
else
return Double.parseDouble(reply.
substring(Const.ERROR.length()));
}
// returns the name of the customer given the code
public String getCustomer( long code) throws Exception{
String reply # sendMessage(Const.GET_CUSTOMER ! " "
! code);
if (reply.startsWith(Const.OK))
return reply.substring(Const.OK.length());
else
return reply.substring(Const.ERROR.length());
}
// communicate a new purchase for the current customer
public void buy( long item, long quantity)
throws Exception {
String reply # sendMessage(Const.BUY ! " " ! item
! " " ! quantity);
if (reply.startsWith(Const.ERROR))
throw new Exception(reply
.substring(Const.ERROR.length()));
}
// terminates the transaction
public void endTransaction() throws Exception {
String reply # sendMessage(Const.END);
if (reply.startsWith(Const.ERROR))
throw new Exception(reply.
substring(Const.ERROR.length()));
}
// disconnect the terminal from the market server
public void disconnect() {
try {
out.write((Const.QUIT ! "\n").getBytes(
out.flush();
} catch (Exception e){ }
socket # null ;