Introduction to Android Application Development, Fourth Edition (2014)

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Exploring the Android SDK

The Android SDK ADT Bundle comes with several major components: the Android Application Framework, Platform Tools, SDK Tools, extras, and sample applications.

Understanding the Android SDK License Agreement

Before you can download the Android SDK ADT Bundle, you must review and agree to the Android SDK License Agreement. This agreement is a contract between you (the developer) and Google (copyright holder of the Android SDK).

Even if someone at your company has agreed to the licensing agreement on your behalf, it is important for you, the developer, to be aware of a few important points:

Rights granted: Google (as the copyright holder of Android) grants you a limited, worldwide, royalty-free, nonassignable, and nonexclusive license to use the SDK solely to develop applications for the Android platform. Google (and third-party contributors) are granting you license, but they still hold all copyrights and intellectual property rights to the material. Using the Android SDK does not grant you permission to use any Google brands, logos, or trade names. You may not remove any of the copyright notices therein. Third-party applications that your applications interact with (other Android apps) are subject to separate terms and fall outside this agreement.

SDK usage: You may only develop Android applications. You may not make derivative works from the SDK or distribute the SDK on any device or distribute part of the SDK with other software.

SDK changes and backward compatibility: Google may change the Android SDK at any time, without notice, without regard to backward compatibility. Although Android API changes were a major issue with prerelease versions of the SDK, recent releases have been reasonably stable. That said, each SDK update does tend to affect a small number of existing applications in the field, thus necessitating updates.

Android application developer rights: You retain all rights to any Android software you develop with the SDK, including intellectual property rights. You also retain all responsibility for your own work.

Android application privacy requirements: You agree that your application will protect the privacy and legal rights of its users. If your application uses or accesses personal and private information about the user (usernames, passwords, and so on), your application must provide an adequate privacy notice and keep that data stored securely. Note that privacy laws and regulations may vary by user location; you as a developer are solely responsible for managing this data appropriately.

Android application malware requirements: You are responsible for all applications you develop. You agree not to write disruptive applications or malware. You are solely responsible for all data transmitted through your application.

Additional terms for specific Google APIs: Use of the Google Maps Android API is subject to further Terms of Service. You must agree to these additional terms before using those specific APIs and always include the Google Maps copyright notice provided. Use of Google APIs (Google apps such as Gmail, Blogger, Google Calendar, YouTube, and so on) is limited to access what the user has explicitly granted permission for during installation time.

Develop at your own risk: Any harm that comes about from developing with the Android SDK is your own fault and not Google’s.

Reading the Android SDK Documentation

The Android documentation is provided in HTML format online at http://d.android.com/index.html. If you would like to have a local copy of the docs, you need to download them using the SDK Manager. Once you have downloaded them, a local copy of the Android documentation is provided in the docs subfolder of the Android installation directory (as shown in Figure 2.4).

Figure 2.4 The Android SDK documentation viewed offline.

Exploring the Core Android Application Framework

The Android application framework is provided in the android.jar file. The Android SDK is made up of several important packages, which are listed in Table 2.1.

Table 2.1 Important Packages in the Android SDK

Several optional third-party APIs are available outside the core Android SDK. These packages must be installed separately from their respective websites. Some packages are from Google, whereas others are from device manufacturers and other providers. Some of the most popular third-party APIs are described in Table 2.2.

Table 2.2 Popular Third-Party Android APIs

Exploring the Core Android Tools

The Android SDK provides many tools to design, develop, debug, and deploy your Android applications. For now, we want you to focus on familiarizing yourself with the core tools you need to know about to get up and running with Android applications. We discuss many Android tools in greater detail in Appendix A, “Mastering the Android Development Tools.”

The Android IDE and ADT

You’ll spend most of your development time in your IDE. This book assumes you are using the Android IDE that comes with the ADT Bundle, because this is the official development environment configuration.

ADT incorporates many of the most important Android SDK tools seamlessly into the Android IDE and provides various wizards for creating, debugging, and deploying Android applications. ADT adds a number of useful functions to the Android IDE. Several buttons are available on the toolbar, including buttons to perform the following actions:

Launch the Android SDK Manager

Launch the Android Virtual Device Manager

Run Android lint

Create a new Android XML resource file

The Android IDE organizes its workspace into perspectives (each a set of specific panes) for different tasks such as coding and debugging. You can switch between perspectives by choosing the appropriate tab in the top-right corner of the Android IDE environment. The Java perspective arranges the appropriate panes for coding and navigating around the project. The Debug perspective enables you to set breakpoints, view LogCat information, and debug. ADT adds several special perspectives for designing and debugging Android applications. The Hierarchy View perspective integrates the Hierarchy Viewer tool into the Android IDE so that you can design, inspect, and debug user interface controls within your applications. The DDMS perspective integrates the Dalvik Debug Monitor Server (DDMS) tool into the Android IDE so that you can attach to emulator and device instances and debug your applications. Figure 2.5 shows the Android IDE toolbar with the Android features (left) and the Android perspectives (right).

Figure 2.5 Android features and perspectives on the Android IDE toolbar.

You can switch perspectives within the Android IDE by choosing Window, Open Perspective or by clicking the appropriate perspective tab in the top-right corner of the Android IDE toolbar.

Android SDK and AVD Managers

The first Android toolbar icon with the little green Android and the down arrow will launch the Android SDK Manager (see Figure 2.6, top). The second Android toolbar icon, looking like a tiny phone, will launch the Android Virtual Device Manager (see Figure 2.6, bottom).

Figure 2.6 The Android SDK Manager (top) and Android Virtual Device Manager (bottom).

These tools perform two major functions: management of Android SDK components installed on the development machine and management of the developer’s AVD configurations.

Much like desktop computers, different Android devices run different versions of the Android operating system. Developers need to be able to target different Android SDK versions with their applications. Some applications target a specific Android SDK, whereas others try to provide simultaneous support for as many versions as possible.

The Android SDK Manager facilitates Android development across multiple platform versions simultaneously. When a new Android SDK is released, you can use this tool to download and update your tools while still maintaining backward compatibility and use older versions of the Android SDK.

The Android Virtual Device Manager organizes and provides tools to create and edit AVDs. To manage applications in the Android emulator, you must configure different AVD profiles. Each AVD profile describes what type of device you want the emulator to simulate, including which Android platform to support as well what the device specifications should be. You can specify different screen sizes and orientations, and you can specify whether the emulator has an SD card and, if so, what its capacity is, among many other device configuration settings.

Android Emulator

The Android emulator is one of the most important tools provided with the Android SDK. You will use this tool frequently when designing and developing Android applications. The emulator runs on your computer and behaves much as a mobile device would. You can load Android applications into the emulator, test, and debug them.

The emulator is a generic device and is not tied to any one specific phone configuration. You describe the hardware and software configuration details that the emulator is to simulate by providing an AVD configuration. Figure 2.7 shows what the emulator might look like with a typical Android 4.3 smartphone-style AVD configuration.

Figure 2.7 The Android emulator (smartphone-style, Jelly Bean AVD configuration).

Figure 2.8 shows what the emulator might look like with a typical Android 4.3 tablet-style AVD configuration. Both Figures 2.7 and 2.8 show how the popular Gallery application behaves differently on different devices.

Figure 2.8 The Android emulator (tablet-style, Nexus 7 Jelly Bean AVD configuration).