INTRODUCTION TO ANDROID

Slide 2 Application Components An Android application is made of up one or more of the following components Activities We will only discuss activities in this chapter Services Broadcast Receivers Content Providers

Slide 3 Application Components (Activities) (1) An Activity has a single screen with a UI Program logic is wired to a screen in a structured way (MVC) A program is initiated by running the default activity An activity is executed via predefined callbacks These are just procedures called by the Android infrastructure Most programs will have several activities

Slide 4 Application Components (Activities) (2) An activity is a class that drives from Activity Then we must override a couple of base class methods onCreate() And several others

Slide 5 Application Components (Activities) ( onCreate indicates that we are overriding a base class method It’s an informative annotation Annotations are used to control compiler behavior Similar to.NET attributes

Slide 6 Application Components (Activities) ( onCreate ) super.onCreate calls the base class method Super is roughly equivalent MyBase in VB It typically appears as the first statement in the method

Slide 7 Application Components (Activities) ( onCreate ) setContentView takes one argument – the resource id corresponding to the activity It associates a particular view with the activity The resource is always named R Layout is the layout that you want to use Followed by the resource id of the layout

Slide 8 Application Components (Layout) (1) A layout describes the visual structure for a UI, such as the UI for an activity It’s an XML document, so you need some familiarity with XML Android provides an XML vocabulary that corresponds to the View classes and subclasses, such as those for widgets and layouts

Slide 9 Application Components (Layout) There are different types of layouts for a screen LinearLayout RelativeLayout Lists and Grids Web

Slide 10 Application Components ( LinearLayout ) LinearLayout aligns child objects vertically or horizontally Use the android:orientation attribute to specify the layout direction (vertical / horizontal) Scrollbars appear if the window length exceeds the screen length

Slide 11 Application Components ( RelativeLayout ) RelativeLayout aligns objects relative to an each other (siblings) Such as: Child A to the left of child B Or align to the parent

Slide 12 Application Components (Buttons and Events) Like a VB button Text or an icon can appear in the visible region They respond to click events (although the syntax differs) on.html

Slide 13 Application Components (Declaring a Button) A button has a width and height The button’s text appears in strings.xml

Slide 14 Application Components (Handling a Click – Method 1) When the user clicks a button, the object receives an onClick event which you can handle

Slide 15 Application Components (Handling a Click – Method 2) The event handler can also be declared programmatically using an anonymous class The book uses this technique

Slide 16 Application Components (Toast) A toast is a form of Android popup The size of the popup is just large enough to render the message If you want the user to respond, use a Notification instead of a toast To create, use the makeText method of the Toast class ics/ui/notifiers/toasts.html

Slide 17 Application Components (Toast Example)

Slide 18 Introduction to Input Controls Button operates like a VB button TextView operates like a VB TextBox CheckBox operates like a VB check box Etc.. All are configured as XML

Slide 19 Strings.xml Strings literals are stored in the file strings.xml

Slide 20 Strings.xml And we reference those strings from the layout.xml

Slide 21 Resource Files Android R.java is an auto-generated file by AAPT (Android Asset Packaging Tool) that contains resource IDs for all the resources of res/ directory If you create any component in the activity_main.xml file, the id for the corresponding component is automatically created in this file The id can be used in the activity source file to perform any action on the component

Slide 22 Resource File (Example)

Slide 23 Creating a First Project Click File, New, Project. Select Android Application Project

Slide 24 Define Application Parameters (1) Don’t use an old Minimum Required SDK

Slide 25 Define Application Parameters (1) The Application Name appears in the store when deployed The Project Name is only relevant to Eclipse The Package Name contains a reverse domain name It must be unique and must not be changed – this is how versioning is performed

Slide 26 Define Application Parameters (2) Minimum Required SDK contains the minimum SDK version on which the application will run Target SDK contains the desired SDK version on which the application will run Compile with contains the SDK version that will be used to compile the application Theme defines basic UI characteristics

Slide 27 Configure Project Create activity

Slide 28 Configure Icons Configuring the icons Just use the defaults

Slide 29 Create Blank Activity Create the default activity This gives you a blank screen (form) (Blank Activity)

Slide 30 Name the Activity and Layout Choose the default values

Slide 31 Application Anatomy (1) The file MainActivity.java contains the java code for the application’s activity (screen) Default methods are created too (onCreate, …)

Slide 32 Application Anatomy (2) The purpose of AndroidManifest.xml is similar to web.config or app.config Simply put, it describes the application

Slide 33 Application Anatomy (3) The folder values\strings.xml contains the application’s textual content

Slide 34 Application Anatomy (4) The file activity_main.xml contains the XML code that describes the user interface layout

Slide 35 Setting up the Emulator (1) We can run programs via an emulator or directly attached to a physical device Using windows, you might need the driver from the device manufacturer

Slide 36 Setting up the Emulator (2) Click Window, Android Device Manager Click Create to create the new device I suggest the following settings

Slide 37 Setting up the Emulator (3) Under Windows set the memory to no more than 512MB

Slide 38 Setting up the Emulator (3)

Slide 39 Starting the Emulator Set the display characteristics Note that it takes a while to start the emulator

Slide 40 Running Hello World The emulator should start and be rendered Again, it takes a while to start

Slide 41 Running Hello World (5) Now run the application

Slide 42 Guidelines for Running on a Native Host (1) First, plug the device in If running Windows, you will likely need a device driver

Slide 43 References m-usb.html m-usb.html