The document provides lessons learned from developing the PlurQ Android application. It discusses challenges with naive assumptions around taking pictures, memory usage, networking, and layouts working across devices. Key lessons include testing on different devices, using the latest APIs, adding permissions only when needed, handling proxies, timeouts and secure connections for networking, and using density-independent units for robust layouts.

1. Naive application development - Learning Android from failure 2010/03/17 shakalaca

2. About shakalaca (shaka) Engineer @ Qisda Android UI development & system integration Where to find me ? @plurk, @facebook, @twitter Contact @gmail.com Published Android App PlurQ / Beauty Clock Widget

3. Outline A short introduction Go ahead and DIY ? Taking picture should be easy ? Lots of memory out there ? Networking is simple as doc told you so ? Upload and your app should be published ? My 2 cents Q & A

4. A short introduction

5. About PlurQ “ Missing the timeline view of Plurk? Enjoying surfing between Plurk mesages? PlurQ provides almost the same look-n-feel as Plurk on your web browser. Feature: -Similar look-n-feel as Plurk on web browser, including the timeline view” - http://www.cyrket.com/p/android/mobi.qiss.plurq/

6. Story of PlurQ API first developed @ 2009/Mar As a practice of getting started with Android River view first developed @ 2009/Sep Inspired by HTC sense™ UI Creating custom view PlurkClient as a Demo Spare time project

7. PlurkClient (former PlurQ)

8. Birth of PlurQ Published @ 2009/12/15 via Qiss A Group of people interested in Android Market “ Shrek” as mascot Cute version of Android Robot Not spare time project anymore Statistics (2010/03/15) 4710 download, 2833 active installs (60%)

9. Screenshot

10. Screenshot

11. Download and play !

12. Go ahead and DIY ?

13. DIY is good, but.. Don’t reinvent wheel Official API Unofficial API Do a search on http://code.google.com/ or http://github.com/ first Bad for PlurQ Not noticing this open source project : http://code.google.com/p/jplurkapi/

14. Analyzing first.. No official API Unofficial Plurk API : http://plurkapi.com (down) Problems Not all methods are listed Input/Output are not match to current state Plurk said there will be official API .. soon ?

15. Go go go ! Fire in the hole ! Shim code Wrapper for underlying API Easy to change difference implementation 2 days after official API released Digg plurk.com Firefox + Live HTTP header add-on ( https://addons.mozilla.org/en-US/firefox/addon/3829 ) Get methods from .js Faster than reading document .

16. Dealing with strange output Format of “date” in return JSON object is wrong ("Mon, 12 Jan 1976 00:01:00 GMT") Solution Copy from android and hack Not used after official API released

17. Taking picture should be easy ?

18. Get picture from camera Use intent Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); startActivityForResult(intent, Common.PLURKPOST_REQ_IMAGE); Get result (thumbnail) protected void onActivityResult(int req, int result, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (result == RESULT_CANCELED) return; switch (req) { case Common.PLURKPOST_REQ_IMAGE: { mBitmapOfSmallerUploadImage = (Bitmap) data.getExtras().getParcelable("data"); doUploadImage(); } break; } }

19. Only thumbnail ? For HTC devices protected void onActivityResult(int req, int result, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (result == RESULT_CANCELED) return; switch (req) { case Common.PLURKPOST_REQ_IMAGE: { mUriImage = data.getData(); mBitmapImage = (Bitmap) data.getExtras().getParcelable("data"); doUploadImage(); } break; } } But for other devices ?

20. Get larger picture Set temp URI at first Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); File tmpFile = File.createTempFile("plurq-camera", ".jpg"); mUriOfPicFromCamera = Uri.fromFile(tmpFile); intent.putExtra(MediaStore.EXTRA_OUTPUT, mUriOfPicFromCamera); startActivityForResult(intent, Common.PLURKPOST_REQ_IMAGE);

21. Get larger picture (cont.) Get result protected void onActivityResult(int req, int result, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (result == RESULT_CANCELED) { if (mUriOfPicFromCamera != null) { File tmpFile = new File(mUriOfPicFromCamera.getPath()); tmpFile.delete(); mUriOfPicFromCamera = null; } return; } switch (req) { case Common.PLURKPOST_REQ_IMAGE: { if (data != null) { mUriImage = data.getData(); mBitmapImage = (Bitmap) data.getExtras().getParcelable("data"); } doUploadImage(); } break; } }

22. Side Story Activity closed after launching camera Sometimes FC after taking picture Analysis Due to memory issue Solution Do no assumptions Do login check when activity starts

23. Lots of memory out there ?

24. Memory is big enough, right ? "640K ought to be enough for anybody" Specs of phones G1 : 192MB HTC Magic : 288MB (or 192MB) HTC Hero : 288MB Nexus One : 512MB

25. Truth is .. http://developer.android.com/intl/zh-TW/reference/android/app/ActivityManager.html getMemoryClass() Return the approximate per-application memory class of the current device. This gives you an idea of how hard a memory limit you should impose on your application to let the overall system work best . The returned value is in megabytes; the baseline Android memory class is 16 (which happens to be the Java heap limit of those devices); some device with more memory may return 24 or even higher numbers. On G1 or most device : 16MB Droid & Nexus One : 24MB

26. BitmapCache Scale down if image is too big BitmapFactory.Options options = new BitmapFactory.Options(); options.inSampleSize = 2; bitmap = BitmapFactory.decodeStream(in,null,options); Remember to clear Catch OutOfMemoryError is not enough HashMap + SoftReference For PlurQ : policy is changing all the time What to cache ? (avatar -> thumbnail -> all ?! When to clear ? (600K -> LRU -> each page)

27. Problem with SKIA What happened in this code ? in = new BufferedInputStream(url.openStream(), 4096); bitmap = BitmapFactory.decodeStream(in); decoder->decode returned false error

28. Solution Use BitmapFactory.decodeByteArray instead Bitmap bitmap = null; InputStream in = null; BufferedOutputStream out = null; try { in = new BufferedInputStream(url.openStream(), 4096); final ByteArrayOutputStream ds = new ByteArrayOutputStream(); out = new BufferedOutputStream(ds, 4096); copy(in, out); out.flush(); final byte[] data = ds.toByteArray(); bitmap = BitmapFactory.decodeByteArray(data, 0, data.length); } catch (...) { } private void copy(InputStream in, OutputStream out) throws IOException { byte[] b = new byte[4096]; int read; while ((read = in.read(b)) != -1) { out.write(b, 0, read); } }

29. Memory optimization tools ddms process heap monitor Memory Analyzer for Eclipse Finding memory leaks

30. Networking is simple as doc told you so ?

31. Problems Users complain Can’t login (a few users) Can’t see picture (some users) Sometimes it takes a long time loading something Analyze Proxy Timeout Secure connection

32. Dealing with proxy Java.net.Proxy private void configureHttpProxy() { this.httpProxyHost = android.net.Proxy.getDefaultHost(); this.httpProxyPort = android.net.Proxy.getDefaultPort(); if (this.httpProxyHost != null && this.httpProxyPort != null) { SocketAddress proxyAddress = new InetSocketAddress( this.httpProxyHost, this.httpProxyPort); this.httpProxy = new Proxy(Proxy.Type.HTTP, proxyAddress); } else { this.httpProxy = Proxy.NO_PROXY; } } urlc = url.openConnection(this.httpProxy); Tips Useful in simulator Some operators use proxy (?)

33. Set timeout Connection timeout & socket timeout HttpParams HttpParams params = new BasicHttpParams(); params.setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 20000); params.setParameter(CoreConnectionPNames.SO_TIMEOUT, 10000); DefaultHttpClient client = new DefaultHttpClient(params); Tips Adjust timeout value with care Weak connection with TWM + Galaxy Auto timeout adjustment

34. Secure connection SchemeRegistry SchemeRegistry schemeRegistry = new SchemeRegistry(); schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80)); schemeRegistry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443)); DefaultHttpClient client = new DefaultHttpClient(new ThreadSafeClientConnManager(params, schemeRegistry), params); Tips Option to toggle Not supported by all phones or operators Exception happened in Galaxy

35. Pretending a browser Change the way fetching images in BitmapCache urlc = url.openConnection(); urlc.setRequestProperty("User-Agent", "Mozilla/5.0"); urlc.setReadTimeout(DEFAULT_READ_TIMEOUT); urlc.setConnectTimeout(DEFAULT_CONN_TIMEOUT); in = new BufferedInputStream(urlc.getInputStream(), 4096);

36. Upload and your app should be published ?

37. Problems Can’t be found in Android Market Tattoo A688 Analysis SDK Layout (screen) Layout (screen) Permission

38. SDK issues Always use the latest Android SDK release 1.6+ Use emulator provided by vendors SE : http://developer.sonyericsson.com/wportal/devworld/home?cc=gb&lc=en Motorola : http://developer.motorola.com/ Put in your AndroidManifest.xml <uses-sdk android:minSdkVersion= &quot;3”/> Not sure: android:targetSdkVersion= &quot;4“

39. Layout (screen) issues res/layout, res/layout-*dpi At least ldpi AndroidManifest.xml <supports-screens android:largeScreens=&quot;true“ android:normalScreens=&quot;true“ android:smallScreens=&quot;true“ android:anyDensity=&quot;true&quot; /> Yeah ! Can be found on Tattoo & A688, but..

40. Ugly layout Because of android:anyDensity=&quot;true&quot; Android won’t auto adjust UI elements UI hell if you’re coding in the wrong way Tips Prefer wrap_content, fill_parent and the dip unit to px in XML layout files ( sp for text) Avoid AbsoluteLayout Do not use hard coded pixel values in your code Use density and/or resolution specific resources http://developer.android.com/intl/zh-TW/guide/practices/screens_support.html#dips-pels

41. Add permission only when needed Story PlurQ is not found on Tattoo market -> Problem solved PlurQ uses camera, should add “ android.permission.CAMERA ” to AndroidManifest.xml PlurQ is not found on Tattoo market, again. Only AndroidManifest.xml differs After hours of testing, remove this stupid change and Booom ! Tips Add permission only when exception occurs.

42. My 2 cents

43. Experience sharing.. Field try is important Buy one ! Borrow one ! Go local store and try it ! Win one ! ADC or ADL ? Record exception log You don’t know WTF is going on with users’ phone Log should be easily turn on/off and get

44. Experience sharing.. (cont.) Don’t be sad when you only have an old G1 If your program can run flawlessly on G1, robustness++ for your application! Don’t be frustrated by your defective Nexus One If your program can survive under the horrible networking environment on NO, robustness++ for your application!

45. Performance tuning Tools Log.* traceview Tips Some UI components can be created later Use AsyncTask if you want to something in background and return result to UI

46. Q & A

47. Any re Q uests or A dvises ?

48. On-going features Social Activity View profile / View plurks / Add friend,fan.. Share via … Widget Notification

49. Wish list Friend Browser / Editor Send private plurk / clique Theme Short url Video upload Search plurker Music listening GPS support

50. Reference Plurk API http://code.google.com/p/jplurk/ http://code.google.com/p/anplurkapi/ http://code.google.com/p/jplurkapi/ Mobile development LG : http://developer.lgmobile.com/lge.mdn.mai.RetrieveMainPage.dev Samsung : http://innovator.samsungmobile.com/ Acer : http://mobile.acer.com/en/developers/