Android dev
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The document provides an overview of the Android platform, development environment, application fundamentals, and performance tips. It discusses that Android is based on the Linux kernel and uses Dalvik as its virtual machine. It also summarizes that the application framework includes activities, services, content providers, and broadcast receivers that communicate via intents. Developers use Java and Android SDK tools to build apps in Eclipse or other IDEs that follow common patterns for layouts, views, resources and user experience.
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Android dev
- 3. Android Platform(2) Linux for device drivers, memory management, process management, networking Next level up is the android native libs, written in c/c++ internally. Call from java interfaces. Dalvik VM. Dalvik runs dex files, converted from standard class file at compile time. Application Framework, for developers
- 4. More about Dalvik It is optimized for low memory requirements, and is designed to allow multiple VM instances to run at once, relying on the underlying OS for process isolation, MM and thread support. one app 16m memory
- 5. Dev environment Java Android SDKs + source code libs, dev tools: dx, aapt, adb, ddms, ant scripts Simulators, docs, sample codes Eclipse + ADT (optional)
- 7. Application Fundamentals Activities/Services/Content Providers/Broadcast receivers Intent(async messaging bundle) Manifest File layouts resources
- 8. Activity Associate with layout-view In stack(could be multiple instances) Lifecycle UI(Main) thread/Other threads: Don’t block the UI thread Do not access the android ui toolkit from outside the UI thread AsyncTask
- 9. intent-example-oauth 1. < activity android:name = ".ArticleActivity" > < intent-filter > < action android:name = "android.intent.action.VIEW" ></ action > < category android:name = "android.intent.category.DEFAULT" ></ category > < category android:name = "android.intent.category.BROWSABLE" ></ category > < data android:scheme = "mashableoauth" android:host = "twitt" ></ data > </ intent-filter > </ activity > 2. ArticleActivity. startActivity( new Intent(Intent. ACTION_VIEW , Uri.parse( requestToken .getAuthenticationURL()))); 3. protected void onNewIntent(Intent intent) { Uri uri = intent.getData(); if (uri != null && uri.toString().startsWith( CALLBACK_URL )) { .... }
- 10. Layout/View Two kinds of UI elements, one is layout(manager), the other is View SDK provides lots of layouts SDK provides lots of views, like list-view, button, text-view, image-view, progress dialog.... custom-view steps(measure then layout) direct use the canvas to draw the view
- 11. Resources drawable assets, (png, xml) strings styles UI patterns ( http://www.google.com/events/io/2010/sessions/android-ui-design-patterns.html )
- 12. Performance Tips Caching (weak reference) Improve ListView ( http://www.google.com/events/io/2010/sessions/world-of-listview-android.html ) Other tips http://www.google.com/events/io/2010/sessions/beginners-guide-android.html devguide( http://developer.android.com/guide/practices/design/performance.html )
- 13. your own app/game? Publishing, no app review on android-market User experience is the most important thing UI/Navigation You have 5 seconds for user operations to finish, but 100-200ms, user feels the lag widgets, notifications, services