Devoxx 2013 - How to make your Android apps suck. A rant.

Litrik De Roy

Android problems to avoid

• crazy permissions. E.g.
  • directly call phone numbers
  • phone status & identity: tracking
  • retrieve other apps running
  • mock location for testing -> test-only settings...
• splash screens :-(
• "menu button of shame" lower right corner of app
• Skeumorphic design
  • try to use iOS design on Android
  • tabs at the bottom of the screen
• spammy notifications: games
• exit confirmation "are you sure you want to exit?" -> doesn't exist..
• portrait only mode
• tabs without swiping
• Jerky scrolling
• themed buttons without selectors -> pressed, selected, active , disabled
• app size (=feature creep)
• flooding logcat (too many debug messages)

Devoxx11: Android awesomeness

Chet Haase, Romain Guy and Philip Milne

Android 4.0: Tablet (3.0) & Phone (2.3) reunited

GridLayout: powerful & flexible lay-outing -- way too complex explanation.

Tools for profiling / debugging Android apps. "Experience matters"

• Memory
  • dumpsys: dump info of processes running on the device
    • adb shell dumpsys meminfocom.android.Launcher: dumps heap usage details
    • dumpsys gfxinfo: graphics chip
    • dumpsys window: decompose window objects used
  • DDMS: heap dump
  • jhat:
    • generate hprof
    • convert it with hprof-conv
    • in eclipse
    • check out "rootset references" for potentially memory leaks
  • MAT: Eclipse Allocation Tracker - http://eclipse.org/mat
• Performance
  • "use your eyes"
  • DDMS
  • track frames per second -> "trackFPS()" call in a PreDrawListener
• UI
  • 'crazy' stuff like high speed cams: Casio Ex-F1: replay the animation in slow motion
  • HierarchyViewer:
    • ViewTree
    • PixelPerfectTree
  • ViewServer

Devoxx11: Android Jumpstart

Lars Vogel

Excellent introduction to the Android development experience.

• tutorials on Android: www.vogella.de
• java --> class -- through dx-tool --> dex
• development environment: ADT for eclipse.
  • emulator: QEMU
  • DDMS: very powerful device debug mode
• API Components:
  • View for single views & ViewGroup for combining
  • Activity: app lifecycle - onPause() is the guaranteed last call to persist data
  • Intent: transitions to other apps
    • Implicit: Android decides
    • explicit: hard coded coupling to called app
  • Toast class: display quick temporary message
  • Preferences
  • DIY Views:
    • onDraw() method
    • Path class
    • selective invalidate() call to improve performance
  • ListActivity & ListAdapter
  • Threading & Async behaviour:
    • Threads: use runOnUiThread for async updates of the UI
    • Services
    • Broadcast & Receiver