Palestra apresentada por Ivan de Aguirre no AndroidDay 2013.

1. Começando com Android
Ivan de Aguirre
@IvAguirre
ivan.aguirre@dextra-sw.com

2. Agenda
• Parte1:
o
•
Fragmentação.
o Aplicações Nativas ou Híbridas?
o Interface
o Android 4.3
Parte2:
o Como o Android gerencia recursos
o Threading
o Memory leaks

3. Fragmentação

4. Fragmentação - níveis de API
4.0.3 - 4.0.4
API 15
Ice Cream
Sandwich

5. Fragmentação - níveis de API
4.1 - API 16
4.2 - API 17
4.3 - API 18
Jelly Bean

6. Fragmentação - níveis de API
android:minSDKVersion

7. Fragmentação - níveis de API
http://developer.android.com/about/
dashboards/index.html#Platform

8. Fragmentação - níveis de API
Google Play Developer Console

9. Fragmentação - níveis de API
android:minSDKVersion=”10”

10. Fragmentação - níveis de API
android:minSDKVersion=”10”
Android Support
Library

11. Fragmentação - tela
OpenSignal
http://opensignal.com/reports/
fragmentation-2013/

12. http://opensignal.com/reports/fragmentation-2013/

13. Fragmentação - tela - Screen Size
small, normal, large, xlarge,
sw600dp, w1024dp, h720dp, ...

14. Fragmentação - tela - Density
dpi = dots per inch (ldpi, mdpi, hdpi,
xhdpi)
dp = density-independent pixel
sp = scale-independent pixel
wrap_content
match_parent

15. <Button
android:id="@+id/btn_ok"
android:layout_width="match_parent"
android:layout_height="100dp"
android:text="@android:string/ok" />

16. Aplicações Nativas X Híbridas
Android, iOS, Windows Phone...

17. Aplicações Nativas X Híbridas
Android, iOS, Windows Phone...
Custo-benefício de três aplicações > Custo
de uma aplicação híbrida ?

18. Aplicações Nativas X Híbridas
Aplicações Nativas
X
Aplicações Híbridas:
código nativo +
+ JavaScript

19. Aplicações Nativas X Híbridas
“You can write amazing Web 2.0 and Ajax apps that look
exactly and behave exactly like apps on the iPhone. (...)
And guess what? There’s no SDK that you need! You’ve
got everything you need if you know how to write apps
using the most modern web standards to write amazing
apps for the iPhone today. So developers, we think we’ve
got a very sweet story for you. You can begin building
your iPhone apps today.”
Steve Jobs, 2007

20. Aplicações Nativas X Híbridas
“You can write amazing Web 2.0 and Ajax apps that look
exactly and behave exactly like apps on the iPhone. (...)
And guess what? There’s no SDK that you need! You’ve
Só que não…
got everything you need if you know how to write apps
using the most modern web standards to write amazing
apps for the iPhone today. So developers, we think we’ve
got a very sweet story for you. You can begin building
your iPhone apps today.”
Steve Jobs, 2007

21. Aplicações Nativas X Híbridas
Martin Fowler, Developing Software for Multiple Mobile
Devices.
http://martinfowler.com/articles/multiMobile/

22. Aplicações Nativas X Híbridas
Martin Fowler, Developing Software for Multiple Mobile
Devices.
http://martinfowler.com/articles/multiMobile/
“but cross-platform
failed for desktop,
so why should we
expect it to succeed
for mobile?”

23. Aplicações Nativas X Híbridas
Martin Fowler, Developing Software for Multiple Mobile
Devices.
http://martinfowler.com/articles/multiMobile/
“but cross-platform
failed for desktop,
so why should we
expect it to succeed
for mobile?”
“To translate to all platforms,
you can only use what all
platforms support - which
means you can only use a
subset of each platform's
behavior.”

24. Aplicações Nativas X Híbridas
Martin Fowler, Developing Software for Multiple Mobile
Devices.
http://martinfowler.com/articles/multiMobile/
“but cross-platform
failed for desktop,
so why should we
expect it to succeed
for mobile?”
“To translate to all platforms,
you can only use what all
platforms support - which
means you can only use a
subset of each platform's
behavior.”
“...UI translation leads you to... The Uncanny
Valley”

25. Aplicações Nativas X Híbridas
“Javascript is too slow for mobile app
use in 2013 (e.g., for photo editing
etc.). It’s slower than native code by
about 5...“
http://sealedabstract.com/rants/whymobile-web-apps-are-slow/

26. Aplicações Nativas X Híbridas
Se sua aplicação mobile for
um diferencial para o seu
negócio considere fazer
nativa.

27. Aplicações Nativas X Híbridas
Que tal site web otimizado para mobile,
que execute no Browser?

28. Interfaces
http://developer.android.com/design

35. Android 4.3
• Bluetooth Low Energy (Smart
Ready).
• Media DRM.
• Interfaces Java para OpenGL ES
3.0.
• Android key store.
• Hardware credential storage.

37. Parte 2
Algumas boas práticas.
Sim... vamos ver um pouco
de código agora :)

38. Gerência de Recursos
0
100%
A
B
C

39. Gerência de Recursos
0
100%
B
C

40. Gerência de Recursos
0
100%
B
C
D

41. Gerência de Recursos
0
100%
C
D

42. Gerência de Recursos
0
100%
C
D
A

43. Gerência de Recursos
Activity:
onSaveInstanceState(Bundle state)
onRestoreInstanceState(Bundle
state)
onCreate(Bundle state)

44. Gerência de Recursos
Fragment:
onSaveInstanceState(Bundle state)
setRetainInstance(boolean retain)
onCreate(Bundle state)
onCreateView(LayoutInflater inflater
,ViewGroup group, Bundle state)
onActivityCreated(Bundle state)

45. Gerência de Recursos
onCreate
onStart
onResume

46. Gerência de Recursos
onCreate
onStart
onResume

47. Gerência de Recursos
onCreate
onStart
onResume
onSaveInstanceState
onPause
onStop
onDestroy

48. Gerência de Recursos
onCreate
onStart
onResume
onSaveInstanceState
onPause
onStop
onDestroy
onCreate
onStart
onResume

49. Gerência de Recursos
onCreate
onStart
onResume
onSaveInstanceState
onPause
onStop
State
onDestroy
onCreate
onStart
onResume

50. Thread de UI
paint
onClick
paint
paint
onReceive
onItemSelected
paint
onPause
onStop
paint
onDestroy

51. Thread de UI
paint
onClick
paint
paint
onReceive
onItemSelected
paint
onPause
onStop
paint
onDestroy
ANR

52. Thread de UI
paint
onClick
paint
paint
onReceive
onItemSelected
paint
onPause
onStop
paint
onDestroy

53. Thread de UI
paint
onClick
paint
paint
onReceive
onItemSelected
paint
onPause
onStop
paint
onDestroy
Worker Thread

54. Thread de UI
paint
onClick
paint
paint
onReceive
onItemSelected
paint
onPause
onStop
paint
onDestroy
Worker Thread

55. Threading
AsyncTask

56. Threading
public class Activity {
public void onCreate(Bundle
savedInstance) {
...
DownloadTask task = new
DownloadTask();
task.execute();
...
}
}

57. Threading
Loader

58. Threading
AsyncQueryHandler
IntentService
Handler
java.lang.Thread #sqn

59. Sincronização
SyncAdapter
GCM
Polling

60. Memory Leaks
http://www.curious-creature.org/
2008/12/18/avoid-memory-leaks-onandroid/
Romain Guy, 2008

61. Memory Leak - Problema
public class Util {
private Context context;
private static Util singleton;
public static Util get(Context context) {
if (singleton == null) {
this.singleton = new Util(context);
}
return singleton;
}
public String getHello() {
return context.getString(R.string.hello);
}
}

62. Memory Leak - Problema
public class MyActivity extends
Activity {
public void onCreate(Bundle
savedInstance) {
...
Util util = Util.get(this);
String hello =
util.getHello();
...
}

63. Memory Leak - Solução 1
public static Util get(Context
context) {
if (singleton == null) {
Context ctx = context
.getApplicationContext();
this.singleton = new
Util(ctx);
}
return singleton;
}

64. Memory Leak - Solução 2
public class Util {
public static String
getHello(Context ctx) {
return ctx.getString(
R.string.hello);
}
}

65. Memory Leak - Solução 2
public class MyActivity {
public void onCreate(Bundle
savedInstance) {
...
String hello =
Util.getHello(this);
...
}
}

66. Perguntas?

67. Muito Obrigado!
Ivan de Aguirre
@IvAguirre
ivan.aguirre@dextra-sw.com