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Climbing Mount Android (June 2011)
The document discusses the Android ecosystem, focusing on content providers, application structures, and development tools. It outlines the key components of Android development, including user interaction, application lifecycle, and activity management, along with tools like the Android SDK and Eclipse IDE. The presentation also highlights challenges in UI design and resource management across different devices and screen resolutions.
Climbing Mount Android (June 2011)
- 1. Climbing Mount Android Rajesh Vasa, 2011 Twitter: @rvasa http://www.rvasa.com 1
- 2. Mobile Eco-System Content Providers (Music/Video/Books) Ad Networks App. Distribution Platform Billing Telephone Handset Cloud Networks OEMs Infrastructure 2 R. Vasa, 2011
- 3. Android Eco-System Content Providers (Music/Video/Books) Google, Amazon App. Ad Networks ** Distribution Google, Double Click Platform Google Checkout Android Billing Google, Amazon Telephone Handset Cloud Networks (OEMs) Infrastructure Samsung, HTC, Motorola, Sony ... 3 R. Vasa, 2011
- 4. Focus of thistalk... Content Providers (Music/Video/Books) Google, Amazon App. Ad Networks ** Distribution Google, Double Click Android Google Checkout Platform Billing Google, Amazon Telephone Handset Cloud ThisNetworks talk will present a(OEMs) development perspective Infrastructure Samsung, HTC, Motorola, Sony ... 4 R. Vasa, 2011
- 5. Talk Overview •Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Activities • Activity Life Cycle (the odd thing) 5 R. Vasa, 2011
- 6. Roadmap - Whereare we? • Devices • What is Android? • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Activities • Activity Life Cycle (the odd thing) 6 R. Vasa, 2011
- 7. Android Device UserInteraction Android devices have three key buttons Menu Back Home 7 R. Vasa, 2011
- 8. Vendors can addadditional buttons 8 R. Vasa, 2011
- 9. There are variationsin physical form But all phones have Home, Menu, & Back Buttons 9 R. Vasa, 2011
- 10. Home Button... • Typically, this will take you back to the Home Screen of the phone • Default behaviour ~ iPhone / iPad button Home 10 R. Vasa, 2011
- 11. Back Button • This will take you back to the previous screen • If app. has only one screen, this will exit app. Personal Opinion: Back iPhone / iPad should borrow this button 11 R. Vasa, 2011
- 12. Menu Button • Shows a contextual menu (if one is available) • Developers can write their own menus • Quite handy (but, causes Usability issues) • Low Discoverability Menu (as open) 12 R. Vasa, 2011
- 13. Android for tabletsis slightly different... Action Bar Where is the menu button? Back, Home (Buttons need not be physical in Android) 13 R. Vasa, 2011
- 14. Tablet Menu IconVisibility is contextual Menu Sadly, menu position is not mandated (yuk?) 14 R. Vasa, 2011
- 15. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Activities • Activity Life Cycle (the odd thing) 15 R. Vasa, 2011
- 16. What is Android? • Android is a platform • Operating System (with primitive API) • Frameworks (incl. components and libraries) Applications Frameworks Android API Operating System (Customised Linux Kernel) 16 R. Vasa, 2011
- 17. Android Programminglanguages: Java, C/C++ Image Source: http://developer.android.com 17 R. Vasa, 2011
- 18. Android is abi-lingual platform C/C++ Java Image Source: http://www.tbray.org 18 R. Vasa, 2011
- 19. Most Android Codeis in Java (but...) ≠ Android Java is not 100% Sun Java 19 R. Vasa, 2011
- 20. Android Java isdifferent (in many ways) No RMI No Bytecode No AWT / Swing UI Different 2D/3D libs Different Class Load Mechanism 20 R. Vasa, 2011
- 21. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Activities • Activity Life Cycle (the odd thing) 21 R. Vasa, 2011
- 22. Development Tools • Android SDK (Compiler and Emulator) • Eclipse IDE + Android Plug-in • Powerful debugger • Visual UI Builder • Ant (Build System) Download from http://developer.android.com 22 R. Vasa, 2011
- 23. Eclipse IDE 23 R. Vasa, 2011
- 24. Eclipse IDE -Graphical UI Editor 24 R. Vasa, 2011
- 25. Android Emulator Permits checking Portrait and Landscape views 25 R. Vasa, 2011
- 26. Emulator is nice.. but phone is better • The emulator runs the Android O/S (you can run any version: 1.6 to 3.0) • Emulates the phone hardware (like VM Ware) • Emulator does not have sensors (e.g. GPS, Gyro, Accelerometer, Cell phone etc.) • It however offers ways to simulate these events • make a phone call to it So, I can send an SMS to the emulator or 26 R. Vasa, 2011
- 27. Emulators Vs Simulator • iOS offers a simulator • Android has gone down the emulator path • Trade-offs (pros and cons), • Simulators start-up faster, good enough • Emulators allow closer to phone hardwareof the O/S easily + checking against rel. 1.6 • Emulators and Simulators cannot mimic real CPU speed, disk speed, network speed etc. (yet!) 27 R. Vasa, 2011
- 28. If your Javais rusty Free e-Book: http://www.mindview.net/Books/TIJ/ 28 R. Vasa, 2011
- 29. Roadmap - Whereare we? • Devices • What is Android? • Development Tools •The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Activities • Activity Life Cycle (the odd thing) 29 R. Vasa, 2011
- 30. The Android Way Convention Configuration Development is organised around a few conventions 30 R. Vasa, 2011
- 31. Android Project Structure(convention) •Source code (src) •Generated code (gen) •Resources (res) •Images (drawable) •Layout of app (layout) •Constants/Strings (values) 31 R. Vasa, 2011
- 32. Needs Resources @MultipleResolutions Convention High Low Medium 32 R. Vasa, 2011
- 33. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Screens (Activities) • Activity Life Cycle (interesting design choice) 33 R. Vasa, 2011
- 34. A Simple AndroidApp. 34 R. Vasa, 2011
- 35. What is involved? • Place UI controls (Text and Image) • Layout the controls • Centre text • Make text large font • Display Image to take up all space 35 R. Vasa, 2011
- 36. Each Screen isan Activity • Android app. is made up of Activities Activity 36 R. Vasa, 2011
- 37. Views are Android’sKey UI Building Block • We need two views on the Activity TextView ImageView 37 R. Vasa, 2011
- 38. Views are Placedinside a View Group • Different types of pre-defined layouts • Linear, Relative, Table, Frame etc.. View Group a.k.a Layout 38 R. Vasa, 2011
- 39. Android App. -Building Blocks Activity Layout Views (View Group) 39 R. Vasa, 2011
- 40. Separation of Concernsin Android Presentation Functionality Layout Definition Activity Class (main.xml) Event Handling, I/O ... 40 R. Vasa, 2011
- 41. UI (Layout) Definition • Layout definition is generally in an XML file • Hand coded or Visual Editor • Can be also be done in Java Code (yuk!) Layout Definition XML File 41 R. Vasa, 2011
- 42. Android Offers anumber of UI Controls • Offers all standard controls and lot more... Progress These are a small subset of available controls 42 R. Vasa, 2011
- 43. View Groups andLayouts • Android offers the following View Groups, • Linear Layout (Horizontal or Vertical) • Absolute Layout (You set X, Y for each View) • Table Layout (Rows and Columns) • Relative Layout ( ) Position relative to other Views • Frame Layout (Show only one view at a time) • Scroll View (Permits scrolling of the screen) •View Groups can be nested 43 R. Vasa, 2011
- 44. Generated Code, Layout& Resources • How did Australia image get into the App.? • How did we set the text to “Australia”? • Conventions • Layout Defined in /layout/main.xml • Resources Placed in /res/drawable-* • String values defined in/values/strings.xml 44 R. Vasa, 2011
- 45. Resources Resources in “res” Convention 45 R. Vasa, 2011
- 46. Resources are givena unique ID A unique reference id to resources is generated by the Android SDK tools Convention 46 R. Vasa, 2011
- 47. Resources and GeneratedIDs Generated Code static final int australia=0x7f020000; 47 R. Vasa, 2011
- 48. A Reference toLayout also Generated All References are Integers 48 R. Vasa, 2011
- 49. Identifiers are usedto access resources This is the Activity Class Reference to the layout (Android Runtime will Render this Layout) 49 R. Vasa, 2011
- 50. Layout is Referredto from Java Code Activity Activity Class (Java) View Group (Layout) Layout Definition (main.xml) 50 R. Vasa, 2011
- 51. Who writes theActivity code? This block of code is created by IDE/SDK when we create new Android project You can also write you own 51 R. Vasa, 2011
- 52. Activity Creation Method called (by Application Launcher) when App is first launched 52 R. Vasa, 2011
- 53. Activity Creation -Layout Rendering Method call will pass the reference to the layout that needs to be rendered on the screen (“Rendering” is a two-pass process: measure and draw) 53 R. Vasa, 2011
- 54. What is the“root” Activity? • How does Android know which Activity to create first? Answer: Application Manifest File 54 R. Vasa, 2011
- 55. Application Manifest File Application Icon Reference Activity Name Category 55 R. Vasa, 2011
- 56. Application Manifest File Category indicates that it can be launched 56 R. Vasa, 2011
- 57. Application Manifest File Mainaction indicates that it is the starting point 57 R. Vasa, 2011
- 58. Layouts and StringInformation • How did we set the text to “Australia” String constant 58 R. Vasa, 2011
- 59. Using Graphical Resources • How did the Australia image get into layout? Layout can refer to resources @drawable is a special tag 59 R. Vasa, 2011
- 60. What is itwith the @ tag? • Constant Resources in Android can be referred using the “@” tag in XML layout • Example: @drawable, @string ... @drawable/australia @drawable/bots 60 R. Vasa, 2011
- 61. @ Tag andMultiple Screen Resolutions • Dealing with multiple screen resolutions @drawable/icon Android Runtime decides best resource to use based on hardware capabilities R. Vasa, 2011
- 62. Significance of hdpi/ldpi/mdpi Different resolution images High-Res, 240 dpi screen Low-Res, 120 dpi screen Med-Res, 160 dpi screen 62 R. Vasa, 2011
- 63. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Screens (Activities) • Life Cycle & interesting design choices 63 R. Vasa, 2011
- 64. Building an Appwith Simple Interaction • Temperature Conversion (C -> F) 64 R. Vasa, 2011
- 65. Views TextView EditText Button TextView 4 Views (UI components) using a Linear Layout 65 R. Vasa, 2011
- 66. Linear Layout (ViewGroup) main.xml (Layout) 66 R. Vasa, 2011
- 67. View Identifiers • We need a way to identify components that we created in the layout • E.g. To read input data from the field @+id TAG creates new identifiers 67 R. Vasa, 2011
- 68. UI Interaction HandlingPattern • Component.setOn......Listener ( handler ) • E.g. button.setOnClickListener • Handler is an anonymous inner class • On...Listener handler = new On....Listener() {} 68 R. Vasa, 2011
- 69. UI Interaction HandlingPattern The View identifiers are defined in XML 69 R. Vasa, 2011
- 70. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Screens (Activities) • Life Cycle & interesting design choices 70 R. Vasa, 2011
- 71. Wiring up MultipleActivities Contact List Activity Contact Details Select Back 71 R. Vasa, 2011
- 72. Activities are Stackedin Android • All current activities are placed on a Stack • Newly started activities come into foreground Foreground/Active Contact Details Back button will Background/ pop top most starts Paused activity from stack Contact List 72 R. Vasa, 2011
- 73. Activities are likemini-processes • Android activities have their own life cycle • Asynchronous Messaging Communication between Activities is done by message Contact List Contact Details 73 R. Vasa, 2011
- 74. Async. messaging called“Intents” intent Contact List Contact Details Activities communicate with each other via Intents 74 R. Vasa, 2011
- 75. Async. messaging called“Intents” Activity-X Photo Viewer view photo intent You can send a general purpose message (intent), all applications capable of handling that Intent will respond Framework prescribes conventions for common intents 75 R. Vasa, 2011
- 76. Roadmap - Whereare we? • Devices • What is Android? • Development Tools • The Android Way • Anatomy of a Simple Android Application • An Interactive Android Application • Dealing with Multiple Screens (Activities) •Life Cycle (& interesting design choices) 76 R. Vasa, 2011
- 77. Android Activities areManaged by O/S Application Activities have a parent application Activity-A Activity-B Activity-C Activity has Life Cycle Application is NOT managed directly by the O/S Life Cycle is Managed by Android Framework 77 R. Vasa, 2011
- 78. Android Activity LifeCycle Activity is re-started when orientation changes Developers have to save and retrieve state if orientation changes 78 R. Vasa, 2011
- 79. Security -- AndroidDevices has User UID (User ID) also has determines Android File System Access Application Permissions The UID is generated at install time based on the signature and package name 79 R. Vasa, 2011
- 80. A Short Plug!!! 80 R. Vasa, 2011
- 81. Mobile Development @Swinburne • HIT8328 - Software Development for Mobile Devices • Android focused • HIT8329 - Creating Data Driven Mobile Applications We Offer • iOS focused Options to Study • Portfolio Based Assessments Just One Subject • We do not just cover API -- thereyoua to learn) conceptual foundation (prepare is strong Teaching material will be available openly shortly 81 R. Vasa, 2011
- 82. Mobile Development @Swinburne • HIT8328 - Software Development for Mobile Devices •Applications HIT8329 - Creating Data Driven Mobile Teaching material will be available under an open license shortly Follow @rvasa or @swinfict for update 82 R. Vasa, 2011