正如我在前面提过的，临时变量可能是个问题。它们只在自己所属的函数中有效，所以它们会助长[冗长而复杂]的函数。这里我们有两个临时变量，两者都是用来
从Customer对象相关的Rental对象中获得某个总量。不论ASCII版或HTML版都需要这些总量。我打算运用Replace Temp with Query(120),并利用所谓的query method来取代totalAmount或frequentRentalPoints这两个临时变量。由于class内的任何函数都可以取用（调用）上述所谓query methods，所以它可能够促进较干净的设计，而非冗长复杂的函数：
class Customer...
public String statement() {
double totalAmount = 0;
int frequentRenterPoints = 0;
Enumeration rentals = _rentals.elements();
String result = "Rental Record for * " + getName() + "\n";
while(rentals.hasMoreElements()) {
Rental each = (Rental)rentals.nextElement(); //取得一笔租借记录
frequentRenterPointers += each.getFrequentRenterPoints();
result += "\t" + each.getMovie().getTitle() + "\t" +
String.valueOf(each.getCharge()) + "\n";
totalAmount += each.getCharge();
}
// add footer lines(结尾打印)
result += "Amount owed is " + String.valueOf(totalAmount) + " \n";
result += "You earned " + String.valueOf(frequentRenterPoints) +
"frequent renter points";
return result;
}
首先我以Customer class的getTotalCharge()取代totalAmount:
class Customer...
public String statement() {
int frequentRenterPoints = 0;
Enumeration rentals = _rentals.elements();
String result = "Rental Record for * " + getName() + "\n";
while(rentals.hasMoreElements()) {
Rental each = (Rental)rentals.nextElement(); //取得一笔租借记录
frequentRenterPointers += each.getFrequentRenterPoints();
result += "\t" + each.getMovie().getTitle() + "\t" +
String.valueOf(each.getCharge()) + "\n";
}
// add footer lines(结尾打印)
result += "Amount owed is " + String.valueOf(getTotalCharge()) + " \n";
result += "You earned " + String.valueOf(frequentRenterPoints) +
"frequent renter points";
return result;
}
// 译注：次即query method
private double getTotalCharge() {
double result = 0;
Enumeration rentals = _rentals.elements();
while(rentals.hasMoreElements()) {
Rental each = (Rental)rentals.nextElement();
result += each.getCharge();
}
return result;
}
这并不是Replace Temp with Query(120)的最简单情况。由于totalAmount在循环内部被赋值，我不得不把循环复制到query method中。