Datasheet

Part I: The Nuts and Bolts of Android

Accelerometer

Android comes packed with accelerometer support. An accelerometer is a

device that measures acceleration. That sounds cool and all, but what can

you do with it? If you want to know whether the phone is moving or being

shaken, or even the direction in which it’s being turned, the accelerometer

can tell you.

You may be thinking, “Okay, but why do I care whether the phone is being

shaken or turned?” Simple! You can use that input as a way to control your

application. You can do simple things like determine whether the phone has

been turned upside down and do something when it happens. Maybe you’re

making a dice game and want to immerse your users in the game play by

having them shake the phone to roll the dice. This is the kind of functionality

that is setting mobile devices apart from typical desktop personal computers.

SD Card

Android gives you the tools you need to access (save and load) files on the

device’s SD Card — a portable storage medium that you can insert into vari-

ous phones and computers. If a device is equipped with an SD Card, you

can use it to store and access files needed by your application. Android 2.2

allows you to install apps on the SD Card, but maybe your users have phones

that don’t get Android 2.2. Just because some users don’t have the option of

installing apps on the SD Card doesn’t mean that you have to bloat your app

with 20MB of resources and hog the phone’s limited built-in memory. You

can download some or all of your application’s resources from your Web

host and save them to the phone’s SD Card. This makes your users happy

and less likely to uninstall your app when space is needed.

Not all devices come with an SD Card installed, although most do. Always

make sure that the user has an SD Card installed and that adequate space is

available before trying to save files to it.

Software Tools

Various Android tools are at your disposal while writing Android applica-

tions. In the following sections, I outline some of the most popular tools that

you will use in your day-to-day Android development process.

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