2.7. Prototypes Are Worth a Thousand Words

It is often said that a picture is worth a thousand words. A prototype is like a picture. A user interface described in text is often harder for the customer to visualize than the same interface described with a diagram or picture. Use cases can provide excellent textual descriptions. A prototype (or screen mockup ) gives a more concrete perspective on a program's intended operation. The prototype can spark feedback from the client in both the program's operation and in missing requirements.

One of the dangers of making a perfect-looking GUI for a prototype is that the interface represents the program to the user. If the interface is complete, the user might expect that the system is almost complete. Some user interface experts suggest that interfaces be designed using whiteboards or Post-it notes. If you are programming in Java, you can use the Napkin Look and Feel (http://napkinlaf. sourceforge .net/). Tim and I created a rough-draft prototype of the screens for the uses cases we worked on with Sam (Figure 2-1). We went over it with Sam. The cases are simple, so he had no changes in its interface. He did note that the buttons should use a large font so that he could read them without his glasses .

Figure 2-1. Rental screens

could read them without his glasses.

PROTOTYPES ARE WORTH A THOUSAND WORDS

A picture of an interface, such as a screen, can be more powerful than just a description.