2. ANDROID L. Grewe

3. Components  Java Standard Development Kit (JDK) (download) http://www.oracle.com... (latest version) http://www.oracle.com...  AndroidStudio  Android SDK

4. What is Android  Android is not an operating system  Android is build on top of Linux Kernel  Android is not equivalent to Linux Kernel  Android is an open source  Android devices sales largest worldwide

5. Android and Java Android does not use the standard JVM Android own its own JVM (Dalvik) Android Dalvik vs standard JVM o register-based vs stack-based o more efficient and compact implementation o different set of java libraries than standard java libraries

6. Android and Java o cannot run standard Java bytecode on Android. o Android provides a tool "dx" which allows to convert Java Class files into "dex" (Dalvik Executable) files. o Android applications are packed into an.apk (Android Package) file by the program "aapt" (Android Asset Packaging Tool) o To simplify development Google provides the Android Development Tools (ADT) with AndroidStudio. The ADT performs automatically the conversion from class to dex files and creates the apk during deployment.

7. Android FrameWork Stack

8. Android Linux Kernel Hardware abstraction layer Memory Management Process Management Networking...

9. Android Native Libraries Bionic Surface Manager 2D and 3D grahics (OpenGL) Media codecs SQLite WebKit...

10. Android Framework ActivityManager Content providers Resource manager Location Manager Notification Manager...

11. Android Application Android applications o google maps o facebook o twitter o...

12. AndroidSDK Tools Docs Platforms o Android XX  Data  Skins  Images  Samples Add-ons o Google API

13. Android Process and Thread Linux process per application Runs under its own userid which is generated automatically by Android system during deployment Hence application isolated from other applications One thread per process o UI Thread o manage Looper message

14. Android Application Components: Android application =collection of loosly coupled components Activity (and fragments) Views Service Intents and Broadcast receiver (Intents reciever) Content provider

15. Activity  presentation layer of an Android application, e.g. a screen which the user sees.  An Android application can have several activities and it can be switched between them during runtime of the application.  Newer introduction of fragments –like mini-activies grouped together to create an activity

16. Activity a single, focused thing that the user can do takes care of creating a window for user presentation to the user o full-screen windows o floating windows o embedding inside of another activity Lifecycle events will invoke the methods of Activity: o void onCreate(Bundle savedInstanceState) o void onStart() o void onRestart() o void onResume() o void onPause() o void onStop() o void onDestroy() The building block of the user interface. The Android analogue for the window or dialog in a desktop application.

17. Android Activity LifeCycle

18. Views  The User interface of an Activities is build with widgets classes which inherent from "android.view.View".  The layout of the views is managed by "android.view.ViewGroups".

19. Services  perform background tasks without providing an UI. Usefull when your app must communicate with backend systems and not make your user wait for it to finish Useful when you app has to do a lot of long calculations and don’t want your user to wail  They can notify the user via the notification framework in Android.  An example --- Pandora App –a music app that can run in background and still play music

20. Service to perform a longer-running operation while not interacting with the user can be started and stopped doesn't have UI run by activities implicit Service (binding service) explicit Service (start service) lifecycle o void onCreate() o void onStart(Intent intent) o void onDestroy()  Examples:  checking for updates to an RSS feed  playing back music even if the controlling activity is no longer operating.

21. Content Provider store and retrieve data and make it accessible to all applications to share data across applications Android contains a SQLite DB which can serve as data provider You can use pre-existing content-providers or you could create an app that itself is a content provider for other applications to use. Think about how some apps use your contact list ---this contact list is a content provider that is built-in/existing already for you to use in your application.

22. Intents an abstract description of an operation to be performed o action o data Explicit Intents (specified a component) Implicit Intents This may be a new idea for you --- it is a asynchronous way of telling the Android System you want to do something We will learn more later about what this means

23. Intents  Intents are system (asynchronous) messages, running around the inside of the device, notifying applications of various events,  hardware state changes (e.g., an SD card was inserted),  incoming data (e.g., an SMS message arrived),  application events (e.g., your activity was launched from the device's main menu).  are asynchronous messages which allow the application to request functionality from other services or activities. An application can call directly a service or activity (explicit intent) or ask the Android system for registered services and applications for an intent (implicit intents). For example the application could ask via an intent for a contact application. Application register themself to an intent via an IntentFilter. Intents are a powerful concept as they allow to create loosely coupled applications.

24. Intents – Explicit, Implicit  An application can call directly a service or activity (explicit intent)  An application can ask the Android system for registered services and applications for an intent (implicit intents).

25. Intents - Example  the application could ask via an intent for a contact application.  Application register themself to an intent via an IntentFilter.  Intents are a powerful concept as they allow to create loosely coupled applications.

26. How to create Intents  You can receive and respond to intents by  intent filters specification  intent/broadcast receivers  You can create your own intents to  launch other activities,  let you know when specific situations arise (e.g., raise an intent when the user gets within 100 meters of a specified location)

27. Android Broadcast Receiver (Intents receiver) receive intents sent by sendBroadcast() two type of broadcasts o Normal broadcast o Ordered broadcast o An application can register as a broadcast receiver for certain events and can be started if such an event occurs.

28. future  We will learn more about what all of these main components of an Android Application are slowly -- -so you will understand through the creation of apps themselves.