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Hãy xem xét một chương trình sổ séc quản lý cá nhân như Quicken. Nó quản lý một số tài khoản ngân hàng và đầu tư và có thể xử lý hóa đơn thanh toán. Bạn có thể sử dụng một mô hình Nhà máy thiết kế một chương trình như thế? 2. | However there are a number of times during each pass through the data where the angle y is zero. In this case your complex math evaluation reduces to Equations 5-8. Ri Ri R2 5 R2 Ri - R2 6 Ii Ii I2 7 2 Ii - I2 8 Then we can make a Simple Factory class that decides which class instance to return. Since we are making Butterflies we ll call this Factory a Cocoon. class Cocoon public Butterfly getButterfly float y if y 0 return new trigButterfly y else return new addButterfly y get multiply class get add sub class lightbulb Thought Questions 1. Consider a personal checkbook management program such as Quicken. It manages several bank accounts and investments and can handle your bill paying. Where could you use a Factory pattern in designing a program like that 2. Suppose that you are writing a program to assist homeowners in designing additions to their houses. What objects might a Factory pattern be used to produce Programs on the CD-ROM Program Description Base Factory Illustrates the Namer factory. Factory Illustration A simple prototype showing a Simple Factory pattern. FFT Illustrates the use of the Simple Factory in FFT. 29 Chapter 4. The Factory Method We have just seen a couple of examples of the simplest of factories. The factory concept recurs throughout OO programming and we find examples embedded in Java itself such as the SocketFactory class and in other design patterns such as the Builder pattern discussed in Chapter 7 . In these cases a single class acts as a traffic cop and decides which subclass of a single hierarchy will be instantiated. The Factory Method pattern is a clever but subtle extension of this idea where no single class makes the decision as to which subclass to instantiate. Instead the superclass defers the decision to each subclass. This pattern does not actually have a decision point where one subclass is directly selected over another subclass. Instead a program written using this pattern defines an abstract class that creates objects .
