Droidcon London 2010 - Day One

I’m heading home with my brain stuffed full of new knowledge from Droidcon London 2010. And this was just the first day, with unplanned, unprepared barcamp-style presentations!

Most of the presentations today were technical (tomorrow there’s a design and business thread as well) but they varied from doing continuous integration through discussing low-level TCP details to a Q&A session with some of Google’s Android team.

I’m seriously looking forward to the second day’s programme.

In the meantime, here’s my notes for the sessions I attended:

Android UI tricks from Sony Ericsson

• limit of 200ms to respond to user interactions — don’t do long running tasks in the UI thread
• so how do you deal with longer lasting processes? use the Handler & Service classes
• …and use Toasts to show quick popup status
• number of devices on 1.5 is below 10%
• all demos will be available on the Sony Ericsson developer blog

Handler

• don’t use inner class Runnables inside a Handler (save heap & garbage collector)
• within XML use onClick for buttons
• handler.sendEmptyMessageDelayed(message, delay);
• then have a message handler that deals with loop & sends next message
  • any UI activity should be in a Runnable called with runOnUiThread(runnable)
• don’t forget onDestroy

Service

• used for downloading
• pass a message from service to activity by implementing your own Application class
• Application defines callback interface and methods to fire & receive
• use IntentService for your service
  • deals with sequential handling automatically
• call to the application (need to cast getApplication())
• don’t use AIDL interfaces — unless you want to share service with other apps or between multiple processes in your app

Animation

• create an AnimationSet and add Animations within the getAnimation call
• second parameters for RotateAnimation are relative to view, not screen
• can also do animations in layout.xml
• Twitter app removed animations from their home screen…
  • the background was a live wallpaper — consumes a lot of battery
  • continuous animations can use up battery so be careful
  • shouldn’t be a problem with performance though
• see also Zooming demo and

BootListener

• when the phone is rebooted, the alarms are cleared
• don’t listen for boot completed unless you really have to
  • slows down startup if you have too many
• can have a broadcast receiver that is disabled
• in app xml set bootlistener disabled by default
• then in listener when intent comes through: {{{ context.getPackageManager().setComponentEnabledSetting( new(ComponentName(context, BootListener.class), PackageManger.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP) }}}

3D & OpenGL with Android views

• combine the strengths of Android views (text, layout, etc) with OpenGL (3D but not text)
• create a bitmap
• use MeasureSpec method
• draw the view onto the OpenGL texture bitmap
• GLUtils.texImage2D(...)
• if you do this today, suggest you use OpenGL ES 2.0

Location services

led by Nick Black, Founder & Head of Products at Cloudmade

cloudmade

• cloudmade will support Android later this year with a Maps SDK
  • based on OpenStreetMaps
  • worked out a way to squeeze vector data onto the device
  • map data comes as you need it and is stored locally on device
  • downloadable data includes searchable street names, etc
  • early access available end of this year, early next year
• cloudmade also has http://maps.cloudmade.com/editor to let you choose and configure your design —- your style will work on mobile too!

Impleo

• formed from ex-Motorola & Alcatel employees
• also adding tracking for insurance
  • includes accelerometer info so can tell how good a driver you are!

cloudmade location-based advertising

• created a network that finds highest value ads from other networks
• goes out to other ad networks, will also go out to more specialist networks
• trying to deal with the fill-rate problem…
• some android apps got backlash when adding advertising after the app release
  • put the ads in at the beginning!

map data

• most owned by Google, Nokia or Tomtom (Navteq)
• skobbler Android app - built on cloudmade’s navigation service
• cloudmade see navigation services not as an app but as a feature within apps
• Google don’t allow access to driving directions API on Android

google latitude and other services

• Is anyone using the latitude API?
• GPS in Android drains the battery quite heavily
• if things are further away then turn off GPS temporarily
• battery management isn’t good built-in
  • have to manage your own choice between coarse and fine location services
• Motorola went to use Skyhook instead of Google location API on Android
  • that way they would get data for their customers WiFi location
  • Google forced them to switch back to Google location
  • Skyhook now suing Google…

Always in sync client & local unit testing

Carl from Novoda (@charroch)[http://twitter.com/charroch]

RESTProvider

• available on github
  • depends on JacksonJSON etc
• makes a RESTful API available as a Content Provider
• couple of branches — caching_carl one stores locally in SQLite
• can start service with loads of requests — it will handle them in a queue
• can add params: putExtra("params", new List(...))
• Tip: adb shell setprop log.tag.Database VERBOSE
  • slows it down a lot
  • can add your own tags too
• ResultReceiver: a way of passing back status to app UI
• if connectivity is lost, it stops the queue
• need to watch out for the user setting to disable background downloading
• extend HttpQueuedService
  • override getMarshaller
  • create a LoggableJsonRequest with a marshall method to store data using a ContentProviderOperation
• library supports ETags too — saves a download as server data is just a HEAD response
• also created novoda.mixml (minimal XML) which works in same way as Jackson JSON
  • integrated into RestProvider to cope with XML content as well as JSON
• hopefully have time to build a more stable version over the new year
• end goal: to have declarations in application XML and service definition

Unit testing of android classes without emulator

• see also the RestProvider code on github
• android.jar only contains stubs, so can’t even instantiate
  • major problem for your subclasses even when you only want to test your additional methods
• PowerMock works somewhat
• need to find a different way of doing the tests
• Carl has copied the source of the Android classes into his test source and modified them to ensure no call to the system…
  • not too hard — just need to ensure that the constructor can work
• have to keep your code copy up to date with the base Android source
  • but it doesn’t matter that much as you won’t be testing Android code
• possible next step: Android will run on Intel — could run locally with unit tests
• currently have three projects:
  1. main classes
  2. local tests using this mechanism
  3. instrumentation tests
• changing to have a single folder with tests marked with annotations
  • want to have some tests marked as local if possible
  • android instrumentation tests should run all of tests (including local tests)
• maven could be overkill for Android development
  • build process is quite well-defined, not that many other libs
• SBT could be interesting (simple build tool, written in Scala)

App Analytics from Capptain

• combining in-app analytics with CRM
• collect/measure -> analysis -> engage
• send messages to users and get feedback
• SDK available in Android and iOS
• similar services: motally (acquired by Nokia) & xtify
• released beta two days ago
• have REST/JSON API for data
  • not publicly available right now, but available on a case-by-case basis

• also have a real-time API

• pricing:

  • free during beta period
  • haven’t decided pricing structure
  • probably freemium — pay for additional functions/users

new analytics capabilities

• how long users are spending in each screen of your app
• really nice user path — based on screens, not events
• real-time analytics — can monitor where people are in your app right now
• crash logs with device, firmware, etc details
• as per other analytics, store data locally and send later if not connected
• Android SDK automatically picks up activities

CRM

• announcements and polls
• target by carrier, country
• test before publish by sending to a single device
• schedule for particular times

Qualcomm Alljoyn

http://developer.qualcomm.com/dev/alljoyn-p2p

• exposes a shared communication bus based on DBus
• automatically uses Wi-Fi and Bluetooth as device allows
• Java and C interfaces
• Java interface lets you just send/receive/call POJOs
• Wi-Fi uses mDNS to find services by well known name (a URI)

Continuous Integration with Maven & Hudson

Hugo Josefson from Jayway (founded Maven Android plugin)

http://code.google.com/p/maven-android-plugin/

Slides and Hudson installation script available from http://code.google.com/p/maven-android-plugin/wiki/Presentations

Android and Maven

• there’s also a proguard plugin — can use to trim unused classes
• maven can handle inter-project dependencies
  • keep pure Java code in a Library (so can have local unit tests)
  • then can have app depend on library and on-device tests depend on app
  • see Samples project for MorseFlash example
• there’s also an Eclipse plugin that helps ADT & Eclipse understand that they’re dealing with Maven
• the process that takes the longest time is the DEXing

Android, Maven and Hudson

• don’t see any reason to run Hudson in Tomcat — it comes with its own webserver
  • though it should work fine within Tomcat too
• Android emulator plugin for Hudson: http://wiki.hudson-ci.org/display/HUDSON/Android+Emulator+Plugin
• emulator settings: 2.2, mdpi, hvga, en_US, 64M
• can loop through different settings for emulator
• Hudson server needs some X libraries but will still run headless
• currently don’t find out which tests fail when Android tests fail — have to look at logs

Google Q & A

I only noted down one question from the second Google Bootcamp Q & A session:

• can you target apps at Android tablets?
  • can target large screen devices (currently Galaxy Tab + Dell Streak)
  • will also hit Evo 4G as that has hi resolution too, but smaller screen