Crittercism Droidcon Berlin 2012

Developing Fault-Tolerant,
“German Engineered” Android Apps

Andrew Levy
andrew@crittercism.com
CEO, co-founder Crittercism

[droidcon ~]$ whoami
• Andrew Levy
– Co-founder & CEO @Crittercism

• Crittercism
– Real-time crash reports and error analysis for mobile
developers
– Analyzed well over a billion application loads in the
past few months
– Backed by Google Ventures, Kleiner-Perkins, and
others

www.crittercism.com - @crittercism

What’s Ahead
1. Testing Difficulties
2. Top 5 Android Crashes
3. iOS vs Android, which crashes less???
4. Quick peak at Crittercism’s Error Analysis
5. Questions
6. Free Stickers


Android Device Diversity
Example app shortly after launch: has 30k DAU, 175k unique users, 50 different devices


iOS Fragmentation

This app has over 850,000
users, 26 diff app versions, 12
different devices


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 J 11, 2008
uly J 15, 2010
uly May 4, 2011

1.1 1.1.5 4.0.1 4.2.9
September 14, 2007 J 15, 2008
uly J 15, 2010
uly J 15, 2011
uly

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 J 15, 2011
uly

1.1.2 2.1 3.0.1 3.1.3 4.0.2 4.2.10
November 12, 2007 September 9, 2008 J 31, 2009
uly February 2, 2010 August 11, 2010 J 25, 2011
uly

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 J 25, 2011
uly

1.0.1 1.1.3 2.0.1 2.2.1 3.1.2 3.2 4.1 4.3.3 5.0
J 31, 2007
uly 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


Android Testing
Build & Test

• Integrated Testing Tools in your IDE
• OEMs (developer.samsung.com, developer.motorola.com, etc)
• 3rd Party Solutions
• Robotium, MonkeyRunner, Robolectric, etc

• Remote Device Testing
• Also offered by OEMs
• Device Anywhere, uTest, Mob4Hire, Perfecto Mobile, etc.

• Crashes still make it out into the wild
• QA Matrix/Permutations


Top 5 Android Crashes
+85% of crashes
1. java.lang.NullPointerException

1. java.lang.OutOfMemoryError

2. android.view.WindowManager$BadTokenException

3. java.lang.IllegalArgumentException &
java.lang.RuntimeException

4. android.database.sqlite.SQLiteException

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 location in code for NPEs seems to be onResume()
– Probably due to devs assuming class members accessible after
onPause()
• Data from intents
• Peripheral/Sensor data (Camera, GPS, etc)
– Some of these errors can be device/manufacturer specific
• Broadcast receivers


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
}


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)
– SoftReferences, recycle
– Pre Honeycomb (<3.0) native heap, now in the normal
heap
• Use hprof -- if using Eclipse, Memory Analyzer (MAT)

ListViews
- Use convertView & viewHolder Pattern

• What about the NDK?
– In the past some devs built their C++ code on
other platforms, then used tools on that platform
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


android.view.WindowManager$BadTok
enException
Biggest Culprit: Dialogs

• Common error for beginners, creating a dialog via
getApplicationContext()
– Android docs are wrong, need to create dialog in context of an Activity


android.view.WindowManager$BadTok
enException
Biggest Culprit: Dialogs

• Anything that changes the context of the activity will cause issues

– Showing a dialog after activity’s onPause is called (phone call, Back, Home, etc)

– Examples
• Screen Rotation during a ProgressBar
– The most common (and not recommended) fix:
» Add android:configChanges="orientation” to manifest, just
onConfigurationChanged is called
– Recommended:
» save your instance state, re-set any activity context references to the new
one
• Launch dialog with an old/null context

– Be sure to use DialogFragment, old dialogs are deprecated


java.lang.IllegalArgumentException
(extends java.lang.RuntimeException)

• Common Examples:

– ContentProvider does not exist
• i.e. try the Network Location Provider in the emulator
• Don’t use undocumented Content Providers

– Using unknown or invalid View IDs
• Confusing a string identifier and integer value wrt setValue()

– Activity is finished already, but you call dismiss on a dialog


java.lang.RuntimeException
• Common Pitfalls

– Forgetting to add an Activity to the Manifest

– Failing to close a camera service before using it again
• Some phones have a race condition with releasing the camera, be sure
to make these calls in surfaceDestroyed
1. cameraObject.setPreviewCallback(null); // prevent race condition
2. cameraObject.stopPreview();
3. cameraObject.release();

– Loading UI elements directly from a background thread

– Trying to use a recycled bitmap


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 connection
– Even if you use threads, share one connection

• Prepared Queries with unknown columns is a common
mistake

• SQL Syntax Errors


Crashes on iOS & Android


Crashes on iOS & Android

Hard to read pie chart

Questions?

Andrew Levy
andrew@crittercism.com
@crittercism and @andrewmlevy

Crittercism Droidcon Berlin 2012

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Editor's Notes