começando com android

Começando com Android

Ivan de Aguirre@IvAguirre

[email protected]

mailto:[email protected]


Agenda• Parte1:

o Fragmentação.o Aplicações Nativas ou Híbridas?o Interfaceo Android 4.3

• Parte2:o Como o Android gerencia recursoso Threadingo Memory leaks

Fragmentação

Fragmentação - níveis de API

4.0.3 - 4.0.4 API 15

Ice Cream Sandwich


4.1 - API 164.2 - API 174.3 - API 18

Jelly Bean


android:minSDKVersion


http://developer.android.com/about/dashboards/index.html#Platform

http://developer.android.com/about/dashboards/index.html%23Platform





Google Play Developer Console


android:minSDKVersion=”10”


android:minSDKVersion=”10”

Android Support Library

Fragmentação - tela

OpenSignalhttp://opensignal.com/reports/

fragmentation-2013/

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




Fragmentação - tela - Screen Size

small, normal, large, xlarge, sw600dp, w1024dp, h720dp, ...

Fragmentação - tela - Density

dpi = dots per inch (ldpi, mdpi, hdpi, xhdpi)

dp = density-independent pixelsp = scale-independent pixel

wrap_contentmatch_parent

Aplicações Nativas X Híbridas

Android, iOS, Windows Phone...


Android, iOS, Windows Phone...

Custo-benefício de três aplicações > Custo de uma aplicação híbrida ?


Aplicações Nativas

X

Aplicações Híbridas:

+ JavaScriptcódigo nativo +


“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


“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

Só que não…

Aplicações Nativas X HíbridasMartin Fowler, Developing Software for Multiple Mobile

Devices.http://martinfowler.com/articles/multiMobile/

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.”







“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”




“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/why-mobile-web-apps-are-slow/






Se sua aplicação mobile for um diferencial para o seu negócio considere fazer

nativa.


Que tal site web otimizado para mobile, que execute no Browser?

http://developer.android.com/design

Interfaces

http://developer.android.com/design/index.html

http://developer.android.com/design/index.html

• Bluetooth Low Energy (Smart Ready).

• Media DRM.

• Interfaces Java para OpenGL ES

3.0.

• Android key store.

• Hardware credential storage.

Android 4.3

Parte 2

Algumas boas práticas.Sim... vamos ver um pouco

de código agora :)

Gerência de Recursos

0 100%

A B C


0 100%

B C


0 100%

B C D


0 100%

C D


0 100%

C D A


Activity:

onSaveInstanceState(Bundle state)

onRestoreInstanceState(Bundle

state)

onCreate(Bundle state)

http://developer.android.com/reference/android/os/Bundle.html


http://developer.android.com/reference/android/app/Activity.html%23onRestoreInstanceState(android.os.Bundle)







Fragment:

onSaveInstanceState(Bundle state)

setRetainInstance(boolean retain)

onCreate(Bundle state)

onCreateView(LayoutInflater inflater

,ViewGroup group, Bundle state)

onActivityCreated(Bundle state)



http://developer.android.com/reference/android/app/Fragment.html%23onCreate(android.os.Bundle)




mailto:(null)

mailto:(null)

mailto:(null)

mailto:(null)

mailto:(null)

mailto:(null)

http://developer.android.com/reference/android/app/Fragment.html%23onActivityCreated(android.os.Bundle)









onCreateonStartonResume



onSaveInstanceStateonPauseonStoponDestroy




onSaveInstanceStateonPauseonStoponDestroy State

Thread de UIpaint

onClickpaintpaint

onReceiveonItemSelected

paintonPauseonStoppaint

onDestroy

Thread de UIpaint

onClickpaintpaint



onDestroy

ANR

Thread de UIpaint

onClickpaintpaint



onDestroy

Thread de UIpaint

onClickpaintpaint



onDestroy

Worker Thread

Threading

AsyncTask

Threadingpublic class Activity { public void onCreate(Bundle

savedInstance) { ... DownloadTask task = new

DownloadTask(); task.execute(); ... }}

Threading

Loader

ThreadingAsyncQueryHandler

IntentService

Handler

java.lang.Thread #sqn

Sincronização

SyncAdapter

GCM

Polling

Memory Leaks

http://www.curious-creature.org/2008/12/18/avoid-memory-leaks-on-

android/

Romain Guy, 2008

http://www.curious-creature.org/2008/12/18/avoid-memory-leaks-on-android/






https://profiles.google.com/111962077049890418486

https://profiles.google.com/111962077049890418486

Memory Leak - Problemapublic 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);

}}

Memory Leak - Problema

public class MyActivity extends Activity { public void onCreate(Bundle

savedInstance) { ... Util util = Util.get(this); String hello =

util.getHello(); ...}

Memory Leak - Solução 1

public static Util get(Context context) { if (singleton == null) { Context ctx = context .getApplicationContext(); this.singleton = new Util(ctx);}return singleton;

}

Memory Leak - Solução 2

public class Util {

public static String getHello(Context ctx) { return ctx.getString( R.string.hello);}

}

Memory Leak - Solução 2public class MyActivity { public void onCreate(Bundle

savedInstance) { ... String hello = Util.getHello(this); ...}

}

Perguntas?

Muito Obrigado!

Ivan de Aguirre@IvAguirre

[email protected]



começando com android

Technology