Introduction to Android Programming
- 1. Agenda ● Introduction ● Android Components overview ● Sample Application ● Android Software Stack ● Android Components detailed – Activity, Service, Provider, Receiver
- 2. History of Android • Android, Inc. – 2003 • Operating system for digital cameras • Google Acquisition – 2005 • Open Handset Alliance – Nov 2007 – Google, HTC, Sony and Samsung – Qualcomm and Texas Instruments • HTC Dream - October 22, 2008
- 4. Application Components • Application components are the essential building blocks of an Android application.
- 5. Application components ● Activity ● Service ● Broadcast Receiver ● Content Provider
- 7. Activities • An activity represents a single screen with a user interface • Example of Activities in Email app – Email List – Compose – Read
- 8. Activities
- 9. Services • A service is a component that runs in the background • A service does not provide a user interface. • Example : Music Player, Downloader
- 10. Services
- 11. Content Provider • Content provider – Allows to share data with other apps •
- 12. Content Provider
- 13. Content Provider
- 14. Broadcast Receiver ● Listener of System wide events. ● Examples – SMS received , Wifi / Bluetooth connected – Battery Low, Device Rebooted ● No UI ● Lightweight ( < 10 seconds )
- 15. Intents IntentsIntents Intents are messages across components. Like Hyperlinks on the web
- 16. Intents ● Support interaction between components – e.g. Start a new Activity – Broadcast messages ● Intents : request for action to be performed
- 17. 17 Types of Intents MyApp Activity1 Service1Intent ( myService.class ) OtherAppMyApp Activity1 Activity2 Explicit Intent Implicit IntentIntent ( “ACTION” ) Intents
- 18. Intents start new Activity ● Dial a number Intent intent = new Intent(Intent.ACTION_DIAL, Uri.parse(“tel:97412345”)); ● Launch a website Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(“http://www.google.com”));
- 19. Intents start new Activity ● Launch another activity Intent i = new Intent(this, SecondActivity.class) startActivity(i)
- 20. Intent Filter ● Registers components as capable of receiving Intents ● Matches intents to the component (Activity , Service, Receivers) ● Declared mostly in AndroidManifest.xml
- 22. <?xml version="1.0" encoding="utf-8"?> <manifest> <uses-permission /> <uses-sdk /> <application> <activity> </activity> </application> </manifest> Application Manifest File
- 23. <?xml version="1.0" encoding="utf-8"?> <LinearLayout> <TextView android:text="I am a TextView" /> <Button android:text="I am a Button" /> </LinearLayout> XML Snippet
- 24. Preview
- 25. Layouts • Linear Layout • Relative Layout • List View • Grid View
- 26. Linear Layout <?xml version="1.0" encoding="utf-8"?> <LinearLayout android:orientation="vertical" > <TextView android:text="I am a TextView" /> <Button android:text="I am a Button" /> </LinearLayout>
- 27. Linear Layout <?xml version="1.0" encoding="utf-8"?> <LinearLayout android:orientation=“horizontal" > <TextView android:text="I am a TextView" /> <Button android:text="I am a Button" /> </LinearLayout>
- 29. UI Widgets
- 30. Sample App <Button android:id="@+id/my_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=“I am a Button"/> Button myButton =(Button)findViewById(R.id.my_button);
- 31. Sample App public void (View v) { // action } Add this in XML file android:onClick="myMethod"
- 32. Sample App ● Extend this to create SecondActivity ● invoked on clicking the button
- 33. Inside the APK ● Compiled Java source ● Libraries ● XML files for UI, strings ● Resources – Images etc ● Android Manifest
- 34. Android Software Stack ● Kernel ● Libraries / Runtime ● Application Framework ● Applications
- 36. Linux kernel • Android built on Linux 2.6 kernel • Provides security, memory management, process management, network stack, and driver model • Abstraction layer between hardware and the software stack
- 37. Libraries • A set of C/C++ libraries exposed to developers through the application framework
- 40. Applications
- 41. Summary ● Android Components ● Android Sample Program ● Activity, Services, Broadcast Receiver ● Intents ● Android Stack