10 ways to improve your Android app performance

1. 10 ways to improve your Android app
Boris Farber
@borisfarber

2. ● Long launch time
● Janky scrolling
● Unresponsive app
Data intensive apps

3. IF YOU HAVE A SMALL APP
FORGET THESE SLIDES

4. 1 - Activity leaks

5. Activity

6. ● Holding references to unused Activity
● Activity holds its layout ⇒ holds all views

7. public class LeakActivity extends Activity {
// ...
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
NastyManager.getInstance().addListener(this);
// ...
Listeners leak

8. @Override
public void onDestroy() {
super.onDestroy();
NastyManager.getInstance().removeListener(this);
}
Listeners leak + fix
remove listener

9. ● Activities/fragments etc - they have a life cycle
● Activity will not be GC-ed
● Static references
○ become dangling "pointers"
○ m_staticActivity = staticFragment.getActivity()
Static References

10. Activity

11. 2 - Activity leaks

12. Outer class (Activity)
Inner class (Handler)

13. public class MainActivity extends Activity {
// ...
Handler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// ...
handler = new Handler() {
@Override
public void handleMessage(Message msg) {
}
};
// ...
This is a leak

14. handler.postDelayed(...)
What happens if

15. private static class MyHandler extends Handler {
private final WeakReference<MainActivity> mActivity;
// ...
public MyHandler(MainActivity activity) {
mActivity = new WeakReference<MainActivity>(activity);
// ...
}
@Override
public void handleMessage(Message msg) {
}
// ...
}
This is a leak + fix

16. Outer class (Activity)
Inner class (Handler)

17. ● Non static Handler → Activity leak
● Both classes have a different a different lifetimes
Prefer static to non static inner classes

18. ● Remove away static references
● Use event bus
● Unregister listeners
● Prefer static inner classes to non static ones
Avoid Activity leaks

19. ● Do code reviews
● Understand your app structure
● Use tools (MAT ...)
● Print logs on callbacks
Avoid Activity leaks

20. 3 - Use UI thread only
for UI

21. ● Scrolling
Symptoms

22. ● Images
● Networking
● JSON
● Database access
Not on UI thread

23. ● Images
● Networking
● JSON
● Database access
Not on UI thread
Use
libraries
Use
Loaders

24. 4 - Use libraries

25. ● Already solve the problem
● Requires specialization (easy to make mistake)
○ Threading
○ Memory
○ Networking
○ Images
Use libraries

26. ● Don’t lose focus
● Developer your solution for a good reason
Use libraries

27. ● Volley
● OkHttp
● Retrofit
Common libraries - Async Http

28. ● Glide
● Picasso
● Fresco
● UIL
Common libraries - Image loading

29. ● Solves your problem
● Plays nicely with your current dependencies
● Dex method count
● Dependencies
● Maintenance
● Runtime permissions
Pick 3rd party lib checklist

30. 5 - Large JSONs

31. ● Parsing has a performance effect
● Converted to class with getters and setters
JSON

32. ● Small JSONs - GSON is the best
● Large JSONs
○ Jackson
○ ig-json-parser
○ GSON + immutables type adapters
JSON

33. ● Keep UI thread only for UI
● Understand concurrency APIs
● Use libraries (memory, caching, json ...)
● Use loaders
Scrolling

34. 6 - System abuse

35. ● Don't call private APIs by reflection
● Don't call private native methods (NDK/C level)
● Don't use Runtime.exec
● "adb shell am" to communicate with other process is not something
we want to support
System abuse

36. ● Don't abuse the system
● Know and use APIs
System abuse

37. 7 - Deprecation

38. ● API will be removed
● Your app will not work
● No way to update APIs and tools
Deprecation

39. ● There is a compelling reason to move
○ Security
○ Correctness
○ Performance
Deprecation

40. ● Removed at M (still available as dependency)
● Use HttpURLConnection
○ Simple API
○ Small size
○ Transparent compression
○ Response caching
Don’t use Apache Http Connection

41. ● Know and use APIs
● Refactor your dependencies
● Update your dependencies and tools
Deprecation

42. 8 - Bring your own
gloves

43. ● Various versions, devices, OEMs
● APIs and libraries shipped with platform might behave differently
● Async task ...
Bring your own gloves

44. ● Consider bundling your own version
● Check dex limit
● Check code bloat
Bring your own gloves

45. ● Own wrapped library (SSL/crypto etc')
● Rooted devices
● Your own sensitive data/protocols
Security

46. 9 - Architecture

47. ● Activities
● Fragments
● Tasks
● Flags
● Add logs on callbacks
Understand app components life cycle

48. ● Consistent
● Get people on board quickly
● Have someone experienced
● Pick your dependencies wisely
What can you do

49. ● Sleeping most of the time
● Responsive when “awaken”
Design your app

50. 10 - Know your APK

51. ● https://goo.gl/94woV7
● Executables browser
● Innovation comes from frustration
ClassyShark

52. tree
view
detail
view

53. ● Dex limit numbers
● Obfuscation
● Package counts
● Why I need the dependency
Know your executable

54. ● https://medium.com/@BorisFarber/
● https://medium.com/@_tiwiz/shrinking-your-build-with-no-rules-
8d9fb88281ac#.j0gb0lf8i
Learn more

55. #ClassyShark
Boris Farber
@borisfarber
Thank You!