Datasheet

30
Part I: Getting Started on BlackBerry Apps
As you can see, letting users enter arbitrary text data forces you to implement
the appropriate conversion method for turning their entries into a form more
suitable for your app to make comparisons and calculations with. However,
a basic text-entry field also allows your users to enter text such as Karl’s
Birthday just as easily.
This text will pretty much crash your application if it tries to add or subtract
days, months, or years to or from it. A better way to ensure that only valid
date values, easily converted to a usable form, are entered is to use UI
components that limit what a user is permitted to enter. In this case, using a
component such as a DateField would be much more appropriate. Unless
you want to give your users more flexibility — which forces you to convert
every possible input to an appropriate, usable form within your app.
Another potential cause of problems is users who download a version of your
app that is not valid for their smartphone OS. Luckily, the BlackBerry App
World gives you the ability to provide multiple versions of your application
customized to the different smartphones that RIM supports. You discover all
this in Chapter 12.
Entering a Brave, New
BlackBerry App World
With the success of the Apple App Store for delivering software to iPhone
devices, major smartphone manufacturers and even some wireless service
providers are designing and deploying their own storefronts to sell applications
designed for their platforms. As mentioned earlier, RIM hosts the BlackBerry
App World, which is an online marketplace for all kinds of BlackBerry
applications. The App World provides many categories of applications for
BlackBerry users to download, such as Business, Education, Games, News,
Shopping, and Utilities. (For the complete list, see Chapter 12).
Each category is further subdivided, allowing prospective buyers to drill
down through the store and find the app that’s right for them. You, as a
developer, should become familiar with the user’s experience of searching
and finding apps in the BlackBerry App World, to place your app in the right
category and to make sure your app shows off its best face. You find out
about all the App World categories and their subcategories in Chapter 12.
Deciding what kind of app to create
If you already have an idea for an app, great! You’ve passed one of the most
difficult steps on your way to BlackBerry App World riches! Figuring out what
05_467114-ch01.indd 3005_467114-ch01.indd 30 8/30/10 1:05 PM8/30/10 1:05 PM