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Android Development in a Nutshell
1. Android development
(in a nutshell)
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Guillem Mayol
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Aleix Solé
EETAC - DXAT
2. Overview
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What is Android
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Android Development
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App Fundamentals
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Framework API
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Framework API: Activities
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Framework API: Tasks
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Framework API: Services
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Framework API: Content Providers
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Framework API: Broadcast Receivers
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Framework API: AndroidManifest.xml
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A simple example
3. What is Android
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„Android is a software stack for mobile
devices that includes an operating
system, middleware and key
applications.“
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Based on the Linux Kernel, open source
libraries, an open source VM to abstract
the phone features (Dalvik) and the
programmable app framework
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All code is Apache v2 licensed
5. Android Development
App Fundamentals
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Apps are written in Java. → .apk files
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Each App has their Linux user ID. →
permissions
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Each process has its own VM → isolation
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An App has only access to necessary
components. → Security & Sharing
6. Android Development
Framework API
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An App can be composed by the next
components:
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Activities : Single screen with user interface.
Ex: Mail App → Its composed by several activities
(List of mails, new message, …)
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Services : A component that runs in the backgroud.
Ex: Listening music while the device is locked.
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Content Providers : Manages a shared set of App
data.
Ex: User's contact info. → ContactsContract.Data
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Broadcast Receivers : Allow to share
announcements
7. Android Development
Framework API : Activities
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Activity States
- Resumed (running)
- Paused (another activity is visible on
top of this one)
*can be killed by System in low mem. Situation.
- Stopped (in the backgroud)
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Activity Lifetime
-Entire Lifetime OnCreate() to OnDestroy()
-Visible Lifetime OnStart() to OnStop()
-Foregroud Lifetime OnResume() to OnPause()
8. Android Development
Framework API : Tasks
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When an activity is launched, the previous ones are
saved to BackStack.
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An activity can start activities that exist in other Apps.
→ A task is a collection of activities that users can
interact with.
9. Android Development
Framework API : Services
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A Service is an App component running in the background and
doesn't provide a user interface.
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A service can take two forms:
- Started [startService()]: Indepently of
father App (can run indefinitely).
Usually a single operation. (Upload file)
- Bound [bindService()]: Depends of
father App.
Usually offers Client-server interface.
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A service can work both ways with:
onStartComand() & onBind()
10. Android Development
Framework API: Contents Providers
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A Content Provider is an App component that
stores and retrieves data and makes it accessible
to all App.
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The data can be stored using Android's file
storage or SQLite databases.
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Each Content Provider exposes a public URI.
Ex: android.provider.Contacts.Phones.CONTENT_URI
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If you want to make own data public, you can:
1. Create your own content provider.
2. Add the data to an existing provider.
11. Android Development
Framework API: Broadcast Receivers
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Most common: Notifications to user. It can be:
1. Toast Notifications → SMS that pops up on screen.
Context context = getApplicationContext();
CharSequence text = "Hello toast!";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text,
duration);
toast.show();
2. Status Bar Notifications → Adds an icon to
the system's status bar with optional SMS.
3. Dialog Notification
12. Android Development
Framework API: AndroidManifest.xml File
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Every App must have this file in its root directory.
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The file contains components description of App.
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These declarations let the Android system know:
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Components that can be used (GPS,...)
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Under what conditions they can be launched
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Permissions of the App. (interact with others)
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Libraries of API (Google Maps)
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.snake">
<application android:label="Snake on a Phone">
<activity android:name="Snake"
android:screenOrientation="portrait"
android:configChanges="keyboardHidden|orientation">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
13. Android Development
Framework API
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SDK publicly available
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http://developer.android.com/sdk/
14. Android development
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After downloading the SDK tools, we also
need the toolchain for debugging and
loading code to targets, and the specific
API for each Android release
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On linux (after extracting the SDK)
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run tools/android
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Install Platform-tools, SDK platform for
the desired Android version, code
samples and documentation
15. Android development
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Eclipse has a plugin specifically designed
for Android development
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Eclipse-ADT
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http://developer.android.com
/sdk/eclipse-adt.html
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Repo a https://dl-ssl.google.com/android/eclipse/
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Since Android itself is open source, an
NDK also exists for native development
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Development at the VM-level, outside
the Java API, using C and C++
16. A simple example
1) Create a new virtual device target,
running some Android version
2) Create a new test project in Eclipse
from one of the SDK samples
3) Run it!
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It will automatically be loaded on the
Virtual Device or on the plugged in
physical device
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Device must run the Android version the
sample code is developed for!
