CS5103 Software Engineering Lecture 08 Android Development II

2 Last class  Projects  Process and Evaluation  Requirements  Calendar  SMS Messenger  Contact Manager  Book Shelf  Android Development I  Android system & Emulator  Environment Setup

3 Today’s class  Basic Android Development  Structure of an android project  Basic UI Components  Activities and Lifecycle  Action bars

4 Play with Emulator  Set environment variables  On the Emulator  Android Debug Bridge  Telnet Interface

5 Set environment variables  Set Android_SDK_Home:  %Android_SDK_Home%/.android will be the place all virtual devices stored  You may set your sdk directory as Android_SDK_Home  Add dirs to PATH env variable  Your sdk directory/tools  Your sdk directory/platform-tools

6 Structure of an Android Project  Source code  Generated code  Manifest file  Resource files

7 Source code & generated code  Source code  The code you will work on  Activities  Typically mainly implementing system call backs  Generated code  The code generated by the system according to your resource files  R.java  Including references to all fields in resource files  Do not edit it

8 Main components of android apps  Main Components  Activities  Services  Broadcast Receivers  They usually can be executed directly with intents  Intents  Messages sent and received between components  System intents

9 Activities  Most important component of an android app  An activity is basically everything showed at one time on the screen  Like window or frame in the desktop UI applications  Explore an app by trigger different activities  An activity has its own resource files

10 Manifest file  Package name  Versions targeted at  Activities  Intent filters  Permissions  Uses-permissions  Declare permissions

11 Permissions  System permissions  Network  Reading/Writing/Sending/Receiving sms  Making/Receiving calls  Reading/writing contacts  Reading/writing SD cards  …  nifest.permission.html nifest.permission.html  User defined permissions

12 Resource files  Source code  The code you will work on  Activities  Typically mainly implementing system call backs  Generated code  The code generated by the system according to your resource files  R.java  Including references to all fields in resource files  Do not edit it

13 Resource files  Drawable  Icons used in the app  Layout  An xml file describing the layout of an activity  Eclipse-ADT provides a graphics layout, and maintain the consistency  Menu  An xml file describing the menu of an activity

14 Resource files  Values  Dimensions  Strings  Styles (color, fonts, etc.)  A project usually has multiple value folders for different targeted devices  Dimensions for different device size  Strings for different languages

15 Today’s class  Basic Android Development  Play with Emulator  Structure of an android project  Basic UI Components  Activities and Lifecycle  Action bars

16 Basic UI Components  Views  Basic UI component  Button, Checkbox, MenuItem, etc.  ViewGroup  A invisible container that holds views  Determines how views are placed in the container  LinearLayout, GridLayout, AbsoluteLayout, etc.

17 Views and View Groups

18 Basic UI Components  Views  Basic UI component  Button, Checkbox, MenuItem, etc.  ViewGroup  A invisible container that holds views  Determines how views are placed in the container  LinearLayout, RelativeLayout, GridView, ListView

19 Add views/viewgroups to a project  All views and view groups can be added by  Editing layout resource file of an activity (recommended)  Edit the graphics layout  Set main attributes  Height  Width  Text / hint

20 Layouts  Linear layouts  Views are placed in a vertical or horizontal list  The default size of views are “wrap_content”  You may set weight for views to make them occupy more spaces

21 Layouts  Relative layouts  Views are placed relative to their neighbors  Views are places from top-left corner by default  Avoid too much hierarchies

22 Layouts  List Views  Bind to ListActivity  A vertical list of scrollable items  Use Adaptor to build and manage items

23 Layouts  Grid Views  Display items in a two-dimensional scrollable grid  Use adaptors to build view and manage items

24 An example of input and display messages

25 Respond to UI components  Add the onclick attribute  The content of the attribute is the name of method to be executed  Access data in the current activity  Find view by id  Do not forget to set an id for the views you want to get data from

26 Respond to UI components  Requirement to the responding method  Public  Return type is void  Has a single parameter: android.view.View  Otherwise the system will not be able to call the responding method

27 Start another activity  Create a new activity  Add it to multiple places (done automatically by eclipse)  Source code  Manifest file  Resource files for the new activity  Generate an intent to start the activity

28 Activity life cycles  Create  Start  The activity become fully visible to the user  Pause:  The activity is partially visible, e.g., pop-up window  Resume  The activity is fully visible again  Stop  The activity is hidden  Destroy

29 Activity life cycles

30 Menus  Menus are by default in the project  Each activity has a menu resource file  A empty action called settings is listed in the menu  Since phone screens are quite small, menu provide a place to put extra buttons that cannot be put onto the screen

31 Add items to menus  Add item to the resource file  Add ids to each item  Implement the method:  onOptionsItemSelected(MenuItem item)

32 Today’s class  Basic Android Development  Play with Emulator  Structure of an android project  Basic UI Components  Activities and Lifecycle  Action bars

33 Thanks!

34 Start an emulator  In eclipse  Go to device manager  Click Start  In command line  emulator –avd ‘virtual device name’

35 On the emulator  Use your keyboard to input text  Useful Shortcuts  Home -> Home  Esc -> back  F2 -> Menu  Ctrl + F12 -> change orientation  Manage Apps  Go to menu -> manage apps  Operating everything as on a phone

36 Adb interface  A very useful tool for controlling emulator  adb devices: show all running emulators  Install and uninstall apps  adb push & pull: transfer data between the host system and the emulator  adb logcat: print the system log of the emulator  adb shell: access the file system of the emulator  Manage files in the virtual device  adb shell pm: List all installed apps

37 Telnet interface  telnet localhost  Simulate a number of events  Phone calls  gsm call  SMS  sms send  Power level  power status charging / not-charging,  power capacity  Set GPS  geo fix

38 Today’s class  Basic Android Development  Play with Emulator  Structure of an android project  Basic UI Components  Activities and Lifecycle  Action bars