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Introduction to Android Programming Contents • Basic Concepts • Environment Setup • Creating and Building Android App Android • Android apps are written in Java • The Android OS is a multi-user Linux system • Android app lives in its own security sandbox • System assigns each app a unique Linux user ID • Each process has its own virtual machine • Every application runs in its own Linux process Application Components • Android Application • .apk : Android package • Four Application Components • Activity • Service • Content Provider • Broadcast Receiver • Communication among components except Content Provider • Intent Activity • Activity Lifecycle • Implement Lifecycle Callbacks Activity • Start an Activity • Start an Activity for a Result • Caller Activity • Callee Activity Activities and Stack Services • A service is a component that runs in the background to perform long-running operations • A service does not provide a user interface • Activity can start the service and let it run or bind to it in order to interact with it e.g., a service might play music in the background while the user is in a different app Broadcast Receivers • A broadcast receiver is a component that responds to system-wide broadcast announcements • Apps can also initiate broadcasts • Although broadcast receivers don't display a UI, they may create a status bar notification to alert the user when a broadcast event occurs Content Providers • A content provider manages a shared set of app data • Through the content provider, other apps can query or even modify the data • Any app with the proper permissions can query part of the content provider Intent • An intent is an abstract description of an operation to be performed • • • • startActivity sendBroadcast startService (bindService) … Environment Setup Step 1: Install JDK JDK Installation • Can download the JDK for your OS at http://java.oracle.com • Alternatively, OS X: • Open "Terminal” • Type javac at command line • Install Java when prompt appears Linux: • Type sudo apt–get install default–jdk at command line (Debian, Ubuntu) • Other distributions: consult the documentation Environment Setup Step 2: Configure the Android SDK SDK Configuration • Download Android SDK from http://developer.android.com Or • Simplest: Download and install Android Studio bundle (including Android SDK) • Eclipse IDE- Official IDE for Android development • Apache Ant for building projects Android Studio • Android Development Environment based on IntelliJ IDEA Android Studio • Android uses Gradle • Gradle is an open source build system that combines the power of Ant and Maven Android Studio Run Android SDK Manager • Recommended: Install Android 2.2, 2.3.3 APIs and 4.x API • Do not worry about Intel x86 Atom, MIPS system images Settings Now you are ready for Android development! Create New Android Project Create Activity The Manifest File • Identify any user permissions the application requires • Declare the minimum API level required by the application • Declare hardware and software features used or required by the application • API libraries the application needs to be linked The Manifest File The Manifest File • Do not forget to declare Components in the Manifest Permission • Add following permissions to the Manifest file Sample Code UI – Declaring Layout • Initiated when called setContentView() on onCreate() • Use Visual Layout Editor for initial layout design • Edit XML file extensively Editing Sample Code Add id to main.xml “@+id/helloId” Edit HelloWorldActivity.java A Sample Code Important points 1 2 3 Hello world! 1. UI Element has an Id 2. Variables in our code link to UI elements 3. Update UI element content from the program UI – Handling UI Events • onClick, onLongClick, onKey, onTouch, … Sample Implementation Option menu MainActivity Context menu Play click Capture CaptureActivity Upload Service Capture Button Click Background Upload PlayerActivity Building Process Running Running Sample App App Failure Debugging, look at DDMS !!! “Dalvik Debug Monitor Service” Enabling USB Debugging Thank You! Any questions *These slides are based on the slides from http://www.comp.nus.edu.sg/~cs5248/l03/L3-ProgrammingInAndroid.pdf
