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CHAPTER 1 HELLO, ANDROID
Notifications are the standard means by which a mobile device traditionally alerts users. Using the API
you can trigger audible alerts, cause vibration, and flash the device’s LED, as well as control status bar
notification icons, as shown in Chapter 9.
Intents provide a mechanism for message-passing within and between applications. Using Intents you
can broadcast a desired action (such as dialing the phone or editing a contact) system-wide for other
applications to handle. Intents are an important core component of Android and are covered in depth
in Chapter 5.
Finally, you can use Content Providers to give managed access to your application’s private databases.
The data stores for native applications, such as the contact manager, are exposed as Content Providers
so you can create your own applications that read or modify this data. Chapter 7 covers Content
Providers in detail, including the native providers, and demonstrates how to create and use providers
of your own.
Using Widgets, Live Folders, and Live Wallpaper to Enhance the
Home Screen
Widgets, Live Folders, and Live Wallpaper let you create dynamic application components that provide
a window into your applications or offer useful and timely information directly on the home screen.
If you offer a way for users to interact with your application directly from the home screen, they get
instant access to interesting information without needing to open an application, and you get a dynamic
shortcut into your application.
You’ll learn how to create application components for the home screen in Chapter 10.
Extensive Media Support and 2D/3D Graphics
Bigger screens and brighter, higher-resolution displays have helped make mobiles multimedia devices.
To help you make the most of the hardware available, Android provides graphics libraries for 2D
canvas drawing and 3D graphics with OpenGL.
Android also offers comprehensive libraries for handling still images, video, and audio files, including
the MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, and GIF formats.
2D and 3D graphics are covered in depth in Chapter 15, while Android media management libraries
are covered in Chapter 11.
Optimized Memory and Process Management
Android’s process and memory management is a little unusual. Like Java and .NET, Android uses its
own run time and virtual machine to manage application memory. Unlike with either of these other
frameworks, the Android run time also manages the process lifetimes. Android ensures application
responsiveness by stopping and killing processes as necessary to free resources for higher-priority
applications.
In this context, the highest priority is given to the application with which the user is interacting. Ensur-
ing that your applications are prepared for a swift death but are still able to remain responsive, and to