Introdução ao desenvolvimento Android - Notas Soltas

Introdução ao
desenvolvimento em
Android
by Tiago Brito

Sunday, February 5, 12

Apps

VATChecker


Apps

Dicionário

VATChecker


Apps

Dicionário

VATChecker

Jogos de
Apostas


Apps

Dicionário

VATChecker

Jogos de
Movies Apostas


Apps

Dicionário

VATChecker

Jogos de
Movies Trânsito Apostas


Apps

Dicionário

VATChecker
Cultura
Jogos de


Apps

Dicionário

VATChecker
Cultura CCilhavo
Jogos de


Apps

Dicionário

VATChecker
Cultura CCilhavo
Jogos de
Horóscopo


Apps

Dicionário
Sinónimos
VATChecker
Cultura CCilhavo
Jogos de
Horóscopo


Apps

Portagens Dicionário
Sinónimos
VATChecker
Cultura CCilhavo
Jogos de
Horóscopo


Apps
From: xxxxx xxxx@priberam.pt
CC: DirecçãoJurídica <DireccaoJuridica@priberam.pt>

Bom dia,

Veriﬁcámos que têm no Android Market uma aplicação que utiliza o conteúdo do Dicionário
Priberam da Língua Portuguesa sem autorização da Priberam nem qualquer referência à
proveniência do conteúdo.

Por essa razão e porque a Priberam disponibilizou uma aplicação sua para o Android de acesso
ao Dicionário, vimos por este meio pedir-vos que retirem a aplicação do Android Market
imediatamente.

Muito obrigado,

xxx xxxxx
Priberam


Petiscos


Trânsito


Smart-lamp
git rep: https://github.com/casainho/smart-lamp


Design tips

• Always try to predict the user text.
• Use the default interface
• New input paradigm. Fingers ≠ mouse
• Size of text. Distance to computer screen ≠
distance to mobile device.
• Visual Information


Target Your App
Serious

content
Entertainment Tool

Fun
usage

Target Your App
Serious

content
Entertainment Tool

Fun
Serious Tool
•Productivity Type usage
•Minimal UI
•Create, modify, archieve


Target Your App
Serious

content
Entertainment Tool

Fun
Fun Tool
• Fun to use and useful usage
• Some graphically rich elements
• Small information hierarchy


Target Your App
Serious

content
Entertainment Tool

Serious Entertainment Fun
• No Productivity
• Educacional entertainment usage
• Data driven
• Potentially hierarchical


Target Your App
Serious

content
Entertainment Tool

Fun
Utilities
• Rich Graphics usage
• Single Screen
• Ag in app 30 to 60s


Dalvik.equals(Java) == false

• The VM runs on top of a Linux 2.6 kernel.

• A tool called dx is used to convert some (but not all) Java .class
files into the .dex format. Multiple classes are included in a
single .dex file. Duplicate strings and other constants used in
multiple class files are included only once in the .dex output to
conserve space. Java bytecode is also converted into an
alternative instruction set used by the Dalvik VM.
• JavaVM’s one can find on almost any desktop computer
nowadays are Stack-based Virtual Machines (VM).The DalvikVM
on the other hand is register based, because on mobile-
processors are optimized for register- based execution. Also of
register-based VMs allow faster execution times at the expense
of programs which are larger after compilation.


Dalvik.equals(Java) == false


Anatomy of an Android
Application

• Activity
• Intent Receiver
• Service
• Content Provider


Activity

• An activity is usually a single screen in your
application
• One activity is designated as the entry point
point for your application


Activity Lifecycle


Activity
public class NotasSoltasActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}

@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
}

@Override
protected void onPause() {
super.onPause();
}

@Override
protected void onRestart() {
super.onRestart();
}

@Override
protected void onResume() {
super.onResume();
}

@Override
protected void onStart() {
super.onStart();
}

Service

A Service is code that is long-lived and runs
without a UI. A good example of this is a media
player playing songs from a play list.


Intents

Intents are asynchronous messages which allow
Android components to request functionality
from other components of the Android
system. For example an Activity can send an
Intents to the Android system which starts
another Activity.


Content Provider
Applications can store their data in ﬁles, a
SQLite database, preferences or any other
mechanism that makes sense. A content
provider, however, is useful if you want your
application's data to be shared with other
applications. A content provider is a class that
implements a standard set of methods to let
other applications store and retrieve the type
of data that is handled by that content
provider.


AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.inovadoor.android.petiscos"
android:versionCode="9"
android:versionName="1.4.2">
<application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="false">
<activity android:name=".Main"
android:label="@string/app_name" android:launchMode="singleTop" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<intent-filter>
<action android:name="android.intent.action.SEARCH" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
<meta-data android:name="android.app.searchable" android:resource="@xml/searchable" />
</activity>
<activity android:name="CategoriasListActivity" android:configChanges="orientation|keyboardHidden"></activity>
<activity android:name="ReceitaDetailsActivity" android:configChanges="orientation|keyboardHidden" ></activity>
<activity android:name="ReceitasListActivity" android:configChanges="orientation|keyboardHidden"></activity>
<activity android:name="SimpleReceitasListActivity" android:configChanges="orientation|keyboardHidden" ></activity>
<activity
android:name=".PreferencesActivity"
android:label="@string/prefsTitle" android:configChanges="orientation|keyboardHidden">
</activity>
</application>
<uses-sdk android:minSdkVersion="3" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
<supports-screens
android:largeScreens="true"
android:normalScreens="true"
android:smallScreens="true"
android:anyDensity="true" />
</manifest>


MVC

Controler

Model View


Development Tools

• Eclipse plugin
• Android SDK


Development Tools
Emulator Simulator

The difference between emulators and simulators is that emulators mimic the software and
hardware environments found on actual devices. Simulators, on the other hand, only mimic the
software environment.


Project
MyProject/
src/
MyActivity.java
res/
drawable/
icon.png
layout/
main.xml
info.xml
values/
strings.xml
values-pt/
strings.xml


Common Problems


Common Problems

• ANR (App Not Responding)
block main thread for more than 5 seconds

• Manifest missing conﬁgurations


Common Problems
Don’t block the main thread


Common Problems
public void onClick(View v) {
new Thread(new Runnable() {
public void run() {
Bitmap b = loadImageFromNetwork();
mImageView.setImageBitmap(b);
}
}).start();
}


Common Problems
public void run() {
Bitmap b = loadImageFromNetwork();
}
}).start();
} public void onClick(View v) {
public void run() {
final Bitmap b = loadImageFromNetwork();
mImageView.post(new Runnable() {
public void run() {
}
});
}
}).start();
}


Common Problems
new DownloadImageTask().execute("http://example.com/image.png");
}

private class DownloadImageTask extends AsyncTask<String, Void,
Bitmap> {
protected Bitmap doInBackground(String... urls) {
return loadImageFromNetwork(urls[0]);
}

protected void onPostExecute(Bitmap result) {
mImageView.setImageBitmap(result);
}
}


Performance
• Avoid Creating Unnecessary Objects
• Avoid Internal Getters/Setters
In native languages like C++ it's common practice to use getters (e.g. i =
getCount()) instead of accessing the field directly (i = mCount). This is an
excellent habit for C++, because the compiler can usually inline the access,
and if you need to restrict or debug field access you can add the code at any
time.
On Android, this is a bad idea.Virtual method calls are expensive, much
more so than instance field lookups. It's reasonable to follow common
object-oriented programming practices and have getters and setters in the
public interface, but within a class you should always access fields directly.

• Prefer Static Over Virtual
If you don't need to access an object's fields, make your method static.
Invocations will be about 15%-20% faster.


Performance
• Use Enhanced For Loop Syntax
static class Foo {
int mSplat;
}
Foo[] mArray = ... public void one() {
int sum = 0;
public void zero() { Foo[] localArray = mArray;
int sum = 0; int len = localArray.length;
for (int i = 0; i < mArray.length; ++i) {
sum += mArray[i].mSplat;    for (int i = 0; i < len; ++i) {
}    sum += localArray[i].mSplat;
}    }
}

public void two() {
int sum = 0;
for (Foo a : mArray) {
sum += a.mSplat;
}
}


Performance

Recycler

Web app VS Native

• If you are building a native app, make sure,
that it will be amazing.
• PhoneGap - http://phonegap.com/
PhoneGap is an HTML5 app platform that allows you to author native
applications with web technologies and get access to APIs and app
stores. PhoneGap leverages web technologies developers already know
best... HTML and JavaScript.


Demo

This slide has been deliberately left blank


Android Market
• 25$ registation fee for developers
• 30 / 70


Android Market


Inspiration

• What app should i make?
• Identify a necessity
• Forget Apps, build a service!
• Use the out-of-the-box phone features: GPS,
Contact List, Google Account, Internet,
Accelerometer, Maps


Market


Market

• Right now, Portuguese market is too
small for mobile ads revenue.
• Take advantage of Portuguese
language
• Think Global.


Market
“The latest Distimo report found that just two paid
Android apps have ever eclipsed the half-million
milestone, while six iPhone apps did that in two months
in April and May.”

“Overall, 79.3 percent of all paid Android apps have
been downloaded less than 100 times, and only 4.6
percent of paid apps were downloaded more than
1,000 times.”
http://gigaom.com/2011/05/27/android-still-trails-ios-as-a-money-maker-for-devs/


Fragmentation
Trânsito Versão Utilizadores
Android 2.3.3+ 1024
Android 1.6 3.1 4.0
Android 4.0.3
Android Android 2.2 763
Android 1.5 Android 2.3
Android 3.2
Android
4% 2%0%
1%
1%
0%
5% Android 2.1 500

Android 2.1
Android 1.5 123
19% Android 1.6 115
Android 2.3.3+ Android 3.1 41
39%
Android 4.0.3 27
Android 2.3 14
Android 4.0 8
Android 2.2
29% Android 3.2 8

Android 2.3.3+ Android 2.2 Android 2.1
Android 1.5 Android 1.6 Android 3.1
Android 4.0.3 Android 2.3 Android 4.0
Android 3.2


Links

• http://developer.android.com
• https://market.android.com/publish

• Dianne Hackborn
• Andrew Munn
• http://blog.crazybob.org/2011/12/truth-about-
android-ios-ui-performance.html


The end

Tiago Brito
tlfbrito@gmail.com
@tlfbrito


Introdução ao desenvolvimento Android - Notas Soltas

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Introdução ao desenvolvimento Android - Notas Soltas