We'll demonstrate few techniques how to provide a better crash experience - advanced logging, detecting memory leaks and hiding crashes from our users.

1. Don’t go crashing my
heart
ŽELJKO PLESAC

2. ANDROID NOWADAYS
• more than 1.4 billions of users
• 23 different SDK versions
• 1,294 device vendors with more than 24,093 distinct
Android devices

3. YOUR USERS DESERVE
BEAUTIFUL APPLICATIONS,
WITH BEST POSSIBLE USER
EXPERIENCE.

4. CRASHES HAVE ENORMOUS
AFFECT ON USER
EXPERIENCE.

5. NOBODY LIKES CRASHES*.
* EXPECT TESTERS

6. PROVIDE BETTER CRASH EXPERIENCE
• you should care about your crashes and try to minimise
them
• optimise your applications in a way, that you can detect
crash even before it occurs

7. 01USE STATIC CODE CHECKERS &
WRITE TESTS

8. Strict rules
• use at least default set of rules
• enforce zero tolerance to all static
code checker warnings and
errors
• aim for high test code coverage
• don’t test only for positive
outcomes, test also for negative
• write stress tests
• always insert at least one test
which will throw an exception or
bug
• all tests have to pass before
merging into development

9. TESTS STABILITY?
Test frameworks have bugs. CI
servers also. Android platform also.

10. HANDLING FAILED TESTS
• all failed tests have to be carefully examined
• if they are not caused by your code, ignore them but test
them once again when new version of testing platform is
available
• this doesn’t mean that everything is not your fault

11. 03USE CONTINUOUS
INTEGRATION

12. CONTINOUS INTEGRATION
• static code checkers & tests automation
• a lot of available products - Jenkins, Travis, CircleCI…
• use protected branches for master and development branch
• use Git flow (or some other pattern)

13. 04HANDLE COMMON ANDROID
PROBLEMS - MEMORY LEAKS

14. MEMORY LEAKS
• they will cause problems and crash your applications
• a lot of great tools

15. A memory leak detection library for Android and Java,
developed by Square (Pierre-Yves Ricau).
De facto standard for detecting memory leaks, use it in your
debug builds.
LEAK CANARY

16. • detects memory leaks in your
application, external libraries,
event Android OS itself
• it will not give you an answer
what is the cause of a leak, just
an information that the leak has
occurred

17. WEAK REFERENCES ARE NOT
THE ANSWER TO
EVERYTHING.

18. 05CRASH FAST

19. CRASH YOU APPLICATIONS AS SOON
AS POSSIBLE
• Square’s approach to handling crashes (presentation and
video)
• organise your code in a way that it crashes as soon as
possible
• use exceptions
• null values are evil

20. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class Person {
private String name;
private String surname;
public Person(String name, String surname) {
this.name = name;
this.surname = surname;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
}

21. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class PersonUtils {
private PersonUtils() {
}
public static String getFullName(Person person) {
return person.getName() + person.getSurname();
}
}

22. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class PersonUtils {
private PersonUtils() {
}
public static String getFullName(Person person) {
if(person != null){
return person.getName() + person.getSurname();
}
else{
return null;
}
}
}

23. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class PersonUtils {
private PersonUtils() {
}
public static String getFullName(Person person) {
if (person == null) {
throw new IllegalStateException("Person cannot be null!”);
}
return person.getName() + person.getSurname();
}
}

24. 06LOG AND MEASURE

25. LOG AND MEASURE YOUR CRASHES
• lot of great tools (Crashlytics, AppsDynamics, Crittercism)
• analyse your crashes
• are crashes happening on custom ROMs?
• are crashes occurring only on cheap phones?
• are your crashes frequent?

27. I don’t care about
warnings, only errors.
- KING HENRIK VIII.

28. TRY-CATCH BLOCK AND EXCEPTIONS
• you should care about your handled exceptions
• they have to be logged and analysed
• should contain useful information

29. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class ProfilePresenterImpl implements ProfilePresenter{
private Person person;
private ProfileView view;
public ProfilePresenterImpl(Profile person){
this.person = person;
}
…
public void showPersonData() {
view.showFullName(PersonUtils.getFullName(person)));
view.showBirthday(PersonUtils.getFormattedBirthday(person)));
view.hideLoadingDialog();
}
}

30. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class ProfilePresenterImpl implements ProfilePresenter{
private Person person;
private ProfileView view;
public ProfilePresenterImpl(Profile person){
this.person = person;
}
…
public void showPersonData() {
String fullName = PersonUtils.getFullName(person));
if(fullName != null){
view.showFullName(PersonUtils.getFullName(person)));
}
view.showBirthday(PersonUtils.getFormattedBirthday(person)));
view.hideLoadingDialog();
}
}

31. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class ProfilePresenterImpl implements ProfilePresenter{
private Person person;
private ProfileView view;
public ProfilePresenterImpl(Profile person){
this.person = person;
}
…
public void showPersonData() {
try{
String fullName = PersonUtils.getFullName(person));
if(fullName != null){
view.showFullName(PersonUtils.getFullName(person)));
}
view.showBirthday(PersonUtils.getFormattedBirthday(person))));}
}
catch(Exception e){
e.prinStackTrace();
view.showErrorDialog();
}
}
}

32. TIMBER
• Utility on top of Android's normal Log class
• by Jake Wharton

33. Timber.plant(new Timber.DebugTree());
Timber.d(...)
Timber.i(...)
Timber.v(...)
Timber.e(...)
Timber.w(...)
Timber.wtf(...)

34. CRASH REPORTING TREE
private static class CrashReportingTree extends Timber.Tree {
@Override
protected void log(int priority, String tag, String message, Throwable t) {
if (priority == Log.VERBOSE || priority == Log.DEBUG) {
return;
}
// will write to the crash report but NOT to logcat
Crashlytics.log(message);
if (t != null) {
Crashlytics.logException(t);
}
}
}

35. CRASH REPORTING TREE
@Override
public void onCreate() {
super.onCreate();
CrashlyticsCore crashlyticsCore = new CrashlyticsCore.Builder()
.disabled(BuildConfig.DEBUG).build();
Fabric.with(this, new Crashlytics.Builder().core(crashlyticsCore).build());
if (BuildConfig.DEBUG) {
Timber.plant(new Timber.DebugTree());
} else {
Timber.plant(new CrashReportingTree());
}
}

36. package co.infinum.crashhandler.sampleapp;
/**
* Created by Željko Plesac on 13/03/16.
*/
public class ProfilePresenterImpl implements ProfilePresenter{
private Person person;
private ProfileView view;
public ProfilePresenterImpl(Profile person){
this.person = person;
}
…
public void showPersonData() {
try{
String fullName = PersonUtils.getFullName(person));
if(fullName != null){
view.showFullName(PersonUtils.getFullName(person)));
}
view.showBirthday(PersonUtils.getFormattedBirthday(person))));}
}
catch(Exception e){
Timber.e(e, “Failure in “ + getClass().getSimpleName());
view.showErrorDialog();
}
}
}

37. /**
* Logs everything to crashlytics, then we just need to log an exception and we
should see all prior logs online!
*/
private static class RemoteDebuggingTree extends Timber.Tree {
@Override
protected void log(int priority, String tag, String message, Throwable t) {
// will write to the crash report as well to logcat
Crashlytics.log(priority, tag, message);
if (t != null) {
Crashlytics.logException(t);
}
}
}

38. 08HIDE CRASHES FROM YOUR
USERS

39. Crashes are just
exceptions,
which are not
handled by your
application*.
* IN MOST CASES

40. APP CRASH HANDLERS
• define custom app crash handler in all of your production
builds
• avoid ugly system dialogs
• simple configuration
• apps are restarted, so they go into stable state
• watch for cyclic bugs!

41. public class AppCrashHandler implements Thread.UncaughtExceptionHandler {
private Activity liveActivity;
public AppCrashHandler(Application application) {
application.registerActivityLifecycleCallbacks(new
Application.ActivityLifecycleCallbacks() {
@Override
public void onActivityResumed(Activity activity) {
liveActivity = activity;
}
@Override
public void onActivityPaused(Activity activity) {
liveActivity = null;
}
});
}
@Override
public void uncaughtException(Thread thread, Throwable ex) {
if(liveActivity != null){
Intent intent = new Intent(getApplicationContext(), MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
liveActivity.finish();
liveActivity.startActivity(intent);
}
System.exit(0);
}
}
CUSTOM CRASH HANDLER

42. APPLICATION CLASS
@Override
public void onCreate() {
super.onCreate();
Thread.setDefaultUncaughtExceptionHandler(new AppCrashHandler(this));
}

43. →
EXAMPLE

44. 08USE STAGED ROLLOUTS

45. STAGED ROLLOUT
• can only be used for app updates, not when publishing an
app for the first time
• your update reaches only a percentage of your users, which
you can increase over time

46. STAGED ROLLOUT PROCESS ①
• at first, define that your update is only available to small
percentage of your users (I.E. 5%)
• closely monitor crash reports and user feedback
• users receiving the staged rollout can leave public
reviews on Google Play
• if everything goes OK, increase the percentage
• if you get negative feedback or encounter some bugs, halt
the process and fix all of reported problems

47. 10HARSH TRUTH

48. YOUR APPS WILL CRASH IN
PRODUCTION, AND THERE IS
NOTHING YOU CAN DO TO
PREVENT IT.

49. THERE IS NO SUCH THING AS 100%
CRASH FREE ANDROID APPLICATION
• large number of different devices
• large number of OS versions
• in most cases, proposed minimum API value is 15 and
the current stable version is 23, which means that your
app has to work on 8 different API versions
• device vendors alter Android OS - they add custom
solutions and bloatware
• rooted Android devices - core functionalities can be altered

50. THINGS ARE GOING TO
BECOME EVEN MORE
COMPLICATED.

51. Phones, tablets, phablets, freezers, smartwatches, cars, bikes,
boards….
ANDROID IS EXPANDING.

52. MultiWindow support, Jack compiler, new APIs, deprecated
APIs, new programming languages…
ANDROID IS GETTING NEW
FEATURES.

53. THAT’S THE BEAUTY OF
ANDROID.

54. DEVELOPERS WILL ALWAYS FIND A WAY.

55. Thank you!
Visit www.infinum.co or find us on social networks:
infinum.co infinumco infinumco infinum
TWITTER: @ZELJKOPLESAC
EMAIL: ZELJKO.PLESAC@INFINUM.CO