German engineering is world renowned for high quality and stability – how come its Android apps can’t be the same? I’m co-founder and CEO of Crittercism, a real-time crash reporting and error analysis platform for mobile apps. Our SDK has recorded hundreds of millions of app loads, and is used by both indie developers and large enterprises like Netflix and AT&T. I have deep insights into what issues are plaguing Android developers the most, which Android platforms are the most difficult to develop on, and finally, which devices cause the most crashes.

1. Developing Fault-Tolerant, !
“German Engineered” Android Apps
Andrew
Levy
andrew@cri/ercism.com
CEO,
co-­‐founder
Cri/ercism

2. [droidcon
~]$
whoami
• Andrew
Levy
– Co-­‐founder
&
CEO
@Cri/ercism
• Cri/ercism
– Real-­‐Cme
crash
reports
and
error
analysis
for
mobile
developers
– Analyzed
well
over
a
billion
applicaCon
loads
in
the
past
few
months
– Backed
by
Google
Ventures,
Kleiner-­‐Perkins,
and
others
www.cri&ercism.com
-­‐
@cri&ercism

3. What’s
Ahead
1. TesCng
DifficulCes
2. Top
5
Android
Crashes
3. iOS
vs
Android,
which
crashes
less???
4. Quick
peak
at
Cri/ercism’s
Error
Analysis
5. QuesCons
6. Free
SCckers
www.cri&ercism.com
-­‐
@cri&ercism

4. Android Device Diversity
Example
app
shortly
a_er
launch:
has
30k
DAU,
175k
unique
users,
50
different
devices
www.cri&ercism.com
-­‐
@cri&ercism

5. iOS Fragmentation
This
app
has
over
850,000
users,
26
diff
app
versions,
12
different
devices
www.cri&ercism.com
-­‐
@cri&ercism

6. iOS
5.0.1
iOS
5.1
How Many iOS Versions Released? November
10
March
7
2011
2012
4.2.5
February 7, 2011
4.2.6
February 10, 2011
4.3
March 9, 2011
4.3.1
March 25, 2011
4.2.7
April 14, 2011
4.3.2
April 14, 2011
1.0 2.0 3.2.1 4.2.8
June 29, 2007 July 11, 2008 July 15, 2010 May 4, 2011
1.1 1.1.5 4.0.1 4.2.9
September 14, 2007 July 15, 2008 July 15, 2010 July 15, 2011
1.1.1 2.0.2 3.0 3.2.2 4.3.4
September 27, 2007 August 18, 2008 June 17, 2009 August 11, 2010 July 15, 2011
1.1.2 2.1 3.0.1 3.1.3 4.0.2 4.2.10
November 12, 2007 September 9, 2008 July 31, 2009 February 2, 2010 August 11, 2010 July 25, 2011
1.0.2 1.1.4 2.2 3.1 4.0 4.2.1 4.3.5
August 21, 2007 February 26, 2008 November 21, 2008 September 9, 2009 June 21, 2010 November 22, 2010 July 25, 2011
1.0.1 1.1.3 2.0.1 2.2.1 3.1.2 3.2 4.1 4.3.3 5.0
July 31, 2007 January 15, 2008 August 4, 2008 January 27, 2009 October 8, 2009 April 3, 2010 September 8, 2010 May 4, 2011 October 12, 2011
iOS Versions
2008 2009 2010 2011 2012
www.cri&ercism.com
-­‐
@cri&ercism

7. Android Testing!
Build
&
Test
• Integrated
TesCng
Tools
in
your
IDE
• OEMs
(developer.samsung.com,
developer.motorola.com,
etc)
• 3rd
Party
SoluCons
• RoboCum,
MonkeyRunner,
Robolectric,
etc
• Remote
Device
TesCng
• Also
offered
by
OEMs
• Device
Anywhere,
uTest,
Mob4Hire,
Perfecto
Mobile,
etc.
• Crashes
sCll
make
it
out
into
the
wild
• QA
Matrix/PermutaCons
www.cri&ercism.com
-­‐
@cri&ercism

8. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

9. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

10. java.lang.NullPointerException
• “works
for
me”
is
not
a
good
test,
there
are
a
thousand
Android
devices
– Assume
the
worst,
common
places
of
NPE:
• #1
locaCon
in
code
for
NPEs
seems
to
be
onResume()
– Probably
due
to
devs
assuming
class
members
accessible
a_er
onPause()
• Data
from
intents
• Peripheral/Sensor
data
(Camera,
GPS,
etc)
– Some
of
these
errors
can
be
device/manufacturer
specific
• Broadcast
receivers
www.cri&ercism.com
-­‐
@cri&ercism

11. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

12. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

13. java.lang.OutOfMemoryError
Memory
Leak
in
Dalvik:
Keeping
a
reference
to
an
object
longer
than
needed
Not
the
best
idea:
try
{
//
allocate
lots
of
objects
}
catch(OutOfMemoryError
oom)
{
//
recycle
some
objects
}
www.cri&ercism.com
-­‐
@cri&ercism

14. java.lang.OutOfMemoryError
Memory
Leak
in
Dalvik:
Keeping
a
reference
to
an
object
longer
than
needed
Biggest
Culprit:
Bitmaps
– memory
usage
• width
px
*
height
px
*
4
bytes
(for
ARGB
images)
– So_References,
recycle
– Pre
Honeycomb
(<3.0)
naCve
heap,
now
in
the
normal
heap
• Use
hprof
-­‐-­‐
if
using
Eclipse,
Memory
Analyzer
(MAT)
ListViews
-­‐
Use
convertView
&
viewHolder
Pa/ern
www.cri&ercism.com
-­‐
@cri&ercism

15. java.lang.OutOfMemoryError
• What
about
the
NDK?
– In
the
past
some
devs
built
their
C++
code
on
other
plaxorms,
then
used
tools
on
that
plaxorm
to
analyze
– New
as
of
November
5,
2011:
• Valgrind
3.7.0
adds
preliminary
ARM
Android
support
(2.3.x)
– May
need
rooted
AOSP
build,
need
libc
with
debug
symbols
www.cri&ercism.com
-­‐
@cri&ercism

16. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

17. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

18. android.view.WindowManager
$BadTokenException
Biggest
Culprit:
Dialogs
• Common
error
for
beginners,
creaCng
a
dialog
via
getApplicaConContext()
– Android
docs
are
wrong,
need
to
create
dialog
in
context
of
an
AcCvity
www.cri&ercism.com
-­‐
@cri&ercism

19. android.view.WindowManager
$BadTokenException
Biggest
Culprit:
Dialogs
• Anything
that
changes
the
context
of
the
acCvity
will
cause
issues
– Showing
a
dialog
a_er
acCvity’s
onPause
is
called
(phone
call,
Back,
Home,
etc)
– Examples
• Screen
RotaCon
during
a
ProgressBar
– The
most
common
(and
not
recommended)
fix:
» Add
android:configChanges="orientaCon”
to
manifest,
just
onConfiguraConChanged
is
called
– Recommended:
» save
your
instance
state,
re-­‐set
any
acCvity
context
references
to
the
new
one
• Launch
dialog
with
an
old/null
context
– Be
sure
to
use
DialogFragment,
old
dialogs
are
deprecated
www.cri&ercism.com
-­‐
@cri&ercism

20. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

21. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

22. java.lang.IllegalArgumentException!
(extends java.lang.RuntimeException)
• Common
Examples:
– ContentProvider
does
not
exist
• i.e.
try
the
Network
LocaCon
Provider
in
the
emulator
• Don’t
use
undocumented
Content
Providers
– Using
unknown
or
invalid
View
IDs
• Confusing
a
string
idenCfier
and
integer
value
wrt
setValue()
– AcCvity
is
finished
already,
but
you
call
dismiss
on
a
dialog
www.cri&ercism.com
-­‐
@cri&ercism

23. java.lang.RuntimeException
• Common
Pixalls
– Forge{ng
to
add
an
AcCvity
to
the
Manifest
– Failing
to
close
a
camera
service
before
using
it
again
• Some
phones
have
a
race
condiCon
with
releasing
the
camera,
be
sure
to
make
these
calls
in
surfaceDestroyed
1. cameraObject.setPreviewCallback(null);
//
prevent
race
condiCon
2. cameraObject.stopPreview();
3. cameraObject.release();
– Loading
UI
elements
directly
from
a
background
thread
– Trying
to
use
a
recycled
bitmap
www.cri&ercism.com
-­‐
@cri&ercism

24. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

25. Top 5 Android Crashes!
+85% of crashes!
1. java.lang.NullPointerException!
!
2. java.lang.OutOfMemoryError"!
3. android.view.WindowManager$BadTokenException"!
4. java.lang.IllegalArgumentException &
java.lang.RuntimeException!
5. android.database.sqlite.SQLiteException!
www.cri&ercism.com
-­‐
@cri&ercism

26. android.database.sqlite.SQLiteException
• Use
the
database
helper,
accessing
DB
file
directly
prone
to
errors
– Read/write
permissions,
SD
card
issues,
etc.
• Use
only
one
SQLite
connecCon
– Even
if
you
use
threads,
share
one
connecCon
• Prepared
Queries
with
unknown
columns
is
a
common
mistake
• SQL
Syntax
Errors
www.cri&ercism.com
-­‐
@cri&ercism

27. Crashes
on
iOS
&
Android
www.cri&ercism.com
-­‐
@cri&ercism

28. Crashes
on
iOS
&
Android
Hard
to
read
pie
chart
www.cri&ercism.com
-­‐
@cri&ercism

29. www.cri&ercism.com
-­‐
@cri&ercism

30. www.cri&ercism.com
-­‐
@cri&ercism

31. Questions?!
Come find us at"
Andrew
Levy
andrew@cri/ercism.com
@cri/ercism
and
@andrewmlevy