Professional Android 4 Application Development Notes

Professional Android 4 Application Development

Chapter 1

Introducting the development framework

• Android applications normally are written using Java, and executed by Dalvik VM.
• Each Android application runs in a separate process within its own Dalvik instance.
• SDK
• NDK

Android Application Architecture

• Activity Manager and Fragment Manager
  
  • to control the lifecycle of your Activities and Fragments
• Views
  
  • to construct the UI
• Notification Manager
  
  • to provide a consistent and nonintrusive mechanism for signaling your uses
• Content Providers
  
  • let your applications share data
• Resource Manager
  
  • enables non-code resources,such as strings and graphics
• Intents
  
  • provide a mechanism for transferring data between applications and their components

Chapter 2

Android Development Tools

• Android Virtual Device and SDK Managers
  
  • to create and manage AVDs
  • to download SDK packages
• Android Emulator
• DDMS (Dalvik Debug Monitoring Service)
  
  • to interrogate active processes
  • to view the stack and heap
  • to watch and pause active threads
  • to explore the filesystem
• ADB (Android Debug Bridge)
  
  • a client-server application
  • a daemon running on the device
  • a server runs on PC
• logcat
  
  • to view and filter the output of the Android logging system
• AAPT (Android Asset Packaging Tool)

additional tools

• ADT plug-in
• SQLite3
• Traceview and dmtracedump
• Hprof-conv
• Dx
  
  • to convert Java .class bytecode into Android .dex bytecode
• Hierarchy Viewer
  
  • to debug and optimize UI
  • to analyze, debug, and optimize the XML layout defi nitions
• Lint
  
  • to optimize your layouts
  • to analyze and optimize your application and resources
• Draw9patch
  
  • to simplify the creation of NinePatch graphics
• Monkey and Monkey Runner
  
  • Monkey runs within the VM, generating pseudo-random user and system events.
  • Monkey Runner provides an API for writing programs to control the VM from outside your application.
  • to test your applications stability from a UI perspective
• ProGuard
  
  • to shrink and obfuscate your code
  • to make your code more difficult to reverse engineer

Chapter 3

What makes an Android Application ?

• Activities
  
  • The UI of your application is built around one or more extensions of the Activity class.
  • Activities use Fragments and Views to layout and display information, and to respond to user actions.
• Services
  
  • Service components run without a UI,updating your data sources and Activities, triggering Notifi cations, and broadcasting Intents.
  • to perform long running tasks, or those that require no user interaction
• Content Providers
  
  • to manage application data and interact with SQL databases
  • to share data across application boundaries
• Intents
  
  • interapplication message-passing framework
  • explicit, implicit and broadcast Intents
• Broadcast Receivers
  
  • Intent listener
  • to listen for Intents that match the criteria you specify
• Widgets
  
  • visual application components that are added to the home screen
• Notifications
  
  • to alert users to application events without stealing focus or interrupting their current Activity

Introducing the Application Manifest file

A Closer Look at the AndroidManifest.xml

<manifest xmlns:android=”http://schemas.android.com/apk/res/android”    package=“com.paad.myapp“    android:versionCode=“1“    android:versionName=“0.9 Beta“    android:installLocation=“preferExternal“>    [ ... manifest nodes ... ]</manifest>

• The manifest tag can include nodes that define the application components, security settings, test classes, and requirements that make up your application.

available manifest sub-nodes

• uses-sdk
  
  • to define a minimum and maximum SDK version
  • to define the target SDK version

<uses-sdk android:minSdkVersion=”6”        android:targetSdkVersion=”15”/>

• uses-configuration
  
  • to specify input mechanisms that are support by your application
  • be useful for games that require particular input controls
  • any combination of reqFiveWayNav, reqHardKeyboard, reqKeyboardType, reqNavigation, reqTouchScreen
  • for example, a device with a finger touchscreen, a trackball, and either a QUERTY or a twelve-key hardware keyboard, as shown here:

<uses-configuration android:reqTouchScreen=”finger”        android:reqNavigation=”trackball”        android:reqHardKeyboard=”true”        android:reqKeyboardType=”qwerty”/>

<uses-configuration android:reqTouchScreen=”finger”        android:reqNavigation=”trackball”        android:reqHardKeyboard=”true”        android:reqKeyboardType=”twelvekey”/>

• uses-feature
  
  • to specify which hardware features your application requires
  • this prevents your application from being installed on a device that doesn’t include a required piece of hardware, such as NFC, as follows:

<uses-feature android:name=”android.hardware.nfc” />

• optional hardware features: audio, bluetooth, camera, location, microphone, nfc, sensors, telephony, touchscreen, usb, wifi

  • supports-screens
• to specify the screen size
• On devices with supported screens, your application is laid out normally using the scaling properties associated with the layout files you supply.
• On unsupported devices the system may apply a “compatibility mode,” such as pixel scaling to display your application.

<supports-screens android:smallScreens=”false”        android:normalScreens=”true”        android:largeScreens=”true”        android:xlargeScreens=”true”        android:requiresSmallestWidthDp=”480”        android:compatibleWidthLimitDp=”600”        android:largestWidthLimitDp=”720”/>

• supports-gl-texture
• uses-permission
  
  • to declare the user permissions your application requires

<uses-permission    android:name=”android.permission.ACCESS_FINE_LOCATION”/>

• permission

  • to create permissions to restrict access to shared application components

• instrumentation

  • to provide a test framework for your application components at run time
  • to monitor your application and its interaction with the system resources

• application

  • to specify the metadata for your application
  • A manifest can contain only one application node
  • The application node also acts as a container for the Activity, Service, Content Provider, and Broadcast Receiver nodes that specify the application components

    <application android:icon=”@drawable/icon”        android:logo=”@drawable/logo”        android:theme=”@android:style/Theme.Light”        android:name=”.MyApplicationClass”        android:debuggable=”true”>        [ ... application nodes ... ]    </application>

application sub-nodes

• activity
  
  • An activity tag is required for every Activity within your application. Trying to start an Activity that’s not defi ned in the manifest will throw a runtime exception.
  • Each Activity node supports intent-filter child tags that define the Intents that can be used to start the Activity

<activity android:name=”.MyActivity” android:label=”@string/app_name”>        <intent-filter>            <action android:name=”android.intent.action.MAIN” />            <category android:name="android.intent.category.LAUNCHER" />        </intent-filter></activity>

• service
  
  • a service tag for each Service class used in your application.
  • Service tags also support intent-filter child tags to allow late runtime binding.

<service android:name=”.MyService”></service>

• provider
  
  • Provider tags specify each of your application’s Content Providers.
  • Content Providers are used to manage database access and sharing.

<provider android:name=”.MyContentProvider”android:authorities=”com.paad.myapp.MyContentProvider”/>

• receiver
  
  • Each receiver node supports intent-filter child tags that define the Intents that can be used to trigger the receiver

<receiver android:name=”.MyIntentReceiver”>    <intent-filter>        <action android:name=”com.paad.mybroadcastaction” />    </intent-filter></receiver>

• uses-library
  
  • to specify a shared library that this application requires
  • You can specify that a particular package is required — which prevents the application from being installed on devices without the specifi ed library — or optional, in which case your application must use refl ection to check for the library before attempting to make use of it

<uses-library android:name=”com.google.android.maps”android:required=”false”/>