Figure 10-18: This program s pull-down menu lets you view a bunch of submenus that you can t access in Java

Paint QR Code in Java Figure 10-18: This program s pull-down menu lets you view a bunch of submenus that you can t access

However, every option on the Attribute submenu appears dimmed, which makes the Attribute submenu useless Why bother showing the users commands that they can t use Not only does this frustrate the user, but the user never knows when any of the Attribute commands might appear undimmed and available for use

A well-designed user interface should always show all possible choices and not overwhelm the users with choices they can t pick anyway

User interfaces are meant for people to use, and it s no surprise that people make mistakes Sometimes they type in the wrong data and sometimes they give a command that they didn t really want to give If you make a mistake, you should be able to Undo or take back that mistake Give the right command or data Unfortunately, too many user interfaces don t let users undo their mistakes, which can make the user anxious and timid because he s afraid that if he does something wrong, he can t ever reverse his mistake As a result, anxious and timid users tend not to trust a program or use it to its maximum capabilities Even worse is when user interfaces provide cryptic feedback if the user does something wrong Examining the error message in Figure 10-19, can you tell what you might have done wrong and what you can do in the future to make sure this error message doesn t appear again

Figure 10-19: A cryptic error message is meaningless and frustrating because the user never knows how to avoid this problem in the future

Cryptic messages can make users feel as if the program is scolding them As a result, users are less likely to enjoy using the program and probably won t take full advantage of all its features either, if they even bother using the program at all

User interfaces should tolerate and expect that the user will make a mistake and then find a way to recover from these mistakes gracefully This can be as simple as having the program beep if the user tries to type his name instead of his Social Security number, or having the program display a descriptive error message that not only tells users what they did wrong but also tells them what to do right By doing this, a user interface can give the user confidence to experiment with a program and learn its features without reading a 300-page manual Instead, the user can gradually figure out how to use a program with the program guiding him every step of the way

One reason why franchise restaurants are so popular is because people know what to expect when they eat there User interfaces also need to make a great first impression on users and then remain consistent so users generally know what to expect from a program at any given time For example, suppose a program displays a toolbox of icons on the left side of the screen Now what happens if the user chooses a command and suddenly the toolbox of icons either disappears or appears in another part of the screen for no apparent reason at all Having the user interface suddenly change its appearance or behavior while the program is running is certain to confuse and annoy users By staying consistent in appearance and behavior, a user interface can be predictable so the user feels more comfortable using it (just as long as the user interface was designed properly in the first place)

Ultimately, the user interface must make it easy for the user to achieve a specific result from the program, whether it involves creating greeting cards, editing digital photos, or typing messages into a blog If the user interface doesn t make the main purpose of the program clear and easy, users don t know or understand what to do The program in Figure 10-20 is designed to help people create stories, but rather than display its various tools for story writing, this program forces users to choose a file to open first At this point, most users will wonder which file to choose, where to find a file, and why they need to open a file if they re using the program for the first time