Object Oriented Design Heuristics

1
private double amountFor(Rental aRental) return
aRental.getCharge()

• initially replace the body with the call
• remove this method later on and call directly

while (rentals.hasMoreElements()) double
thisAmount 0 Rental each (Rental)
rentals.nextElement() thisAmount
each.getCharge() the rest continues as
before
2
frequent renter points

• Lets do the same thing with the logic to
  calculate frequent renter points
• extract method
• each can be parameter
• frequentRenterPoints has a value before the
  method is invoked, but the new method does not
  read it we simply need to use appending
  assignment outside the method.
• move method
• Again, we are only using information from Rental,
  not Customer, so lets move getFrequentRenterPoint
  s to the Rental class.
• Be sure to run your test cases after each step

3
// add frequent renter points frequentRenterPoint
s // add bonus for two day new release
rental if ((each.getMovie().getPriceCode()
Movie.NEW_RELEASE)
each.getDaysRented() gt 1) frequentRenterPoint
s // show figures for this rental result
\t each.getMovie().getTitle() \t
String.valueOf(thisAmount)
\n totalAmount thisAmount // end while