Thursday 28 October 2010

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


  • 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


  • 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


  • 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


  • 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 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 to let you choose and configure your design —- your style will work on mobile too!


  • 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)[]


  • 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


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

Qualcomm Alljoyn

  • 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)

Slides and Hudson installation script available from

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:
  • 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