Multimedia Mobile Programming Pertemuan 9

(1)

Android GUI

Project

(2)

Android

• _{1. Android Basics}

• _{2. Android Development}

• _{3. Android UI}

• _{4. Hello, World}

(3)

Android Basics

• _{Open source OS}

• _{Uses Linux kernel}

• _{Optimized for limited-resource environment}

• _{Apps typically written in Java}

• _{Apps run on the Dalvik Virtual Machine}

• _{Not a JVM, but works similarly from}

developer’s point of view

• _{Usually one app per DVM}

• _{Each DVM runs under Linux as a separate}

user

• _{App permissions set at install time}

• _{Possible to use C or C++ compiled to machine}

code, but still runs on VM. It’s not clear to me how this works.

• _{Docs say it does not necessarily improve}

(4)

Sams Teach Yourself Android™Application Development in 24 Hours (0321673352)

(5)

Android Development

• _{Well-defned framework for app}

development

• _{Apps are typically coded using Java}

syntax, but other parts of the Java

platform are missing

• _{Some standard Java SE or ME APIs and}

class libraries are not included

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Android Development

• _{Standard development environment is Eclipse}

+ Android Development Tools plugin + Android SDK

• _{Development requires either an Android OS}

device or an emulator

• _{Emulator has limitations:}

• Performance is poor

• Camera, etc., simulated using your computer’s hardware

• No real phone calls or texts

• GPS data, battery readings, etc. must be simulated

• _{Real device is afected by specifc hardware}

(7)

Android vs. Other

Mobile OS

I was able to choose what kind of smart phone to get according to which platform I wanted to use to try mobile development

Android:

•_{I had Java backend code ready to go for a frst}

project

•_{Interesting platform:}

• _{Familiar programming environment} • _{Currently the market leader}

• _{Broad market, unlike more focused iOS,}

Blackberry, and (Palm) webOS

• _{Development tools are open source and are}

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Android App vs. Mobile- Optimized

RIA

• _{Android Flash plugins available; Silverlight}

coming soon

• _{Could develop in JavaScript and/or HTML5}

• _{WWW App}

• _{Easier for users to run; no need to install} • _{For a paid app, avoid the 30% App Store}

commission

• _{Easier to write cross-platform apps}

• _{Android Apps}

• _{Fewer security hurdles}

• _{Use APIs for access to built in GPS, camera,}

etc.

(9)

Android Apps: Marketing

• _{Usually market apps through Android App Market}

• _{There are other markets, also}

• _{App store will dominate the market due to}

access through built in app

• _{Can set up for download directly on a website}

• _{User must agree to “install apps from unknown}

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Android Apps: Marketing

• _{Revenue from app sales prices and/or advertising}

• _{Conventional wisdom is that iOS users will pay}

for apps, but Android users won’t

• _{57% of Android App Store apps are free, vs.}

28% for Apple App Store

• _{Android Market takes 30% commission}

• _{Any purchase model other than one-time}

purchase must be homegrown, using Paypal or similar service

• _{PPC ads}

• _{My guess is that response to these is}

extremely low

• _{Probably need to be very aggressive with}

banner ads

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Android Deployment

• _{Apps are packaged in .apk format,}

variant of .jar, then downloaded to

device and installed

• _{.apks contain .dex fles (bytecode),}

manifest and various other fles

• _{Manifest contains security and link}

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Android UI

• _{Activity: single screen with a UI, somewhat}

analogous to XAML / code behind pattern in .NET

• _{Email app might have one activity that}

shows a list of new emails, another activity to compose an email, and another activity for reading emails

• _{Implement by subclassing Activity class}

• _{View: drawable object}

• _{Android UI View}

≠

_{MVC View}

• _{UI contains a hierarchy of Views}

• _{View is a class, subclassed by the drawable}

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Android UI

• _{Service: background operation}

• _{play music in the background while the}

user is in a diferent application

• _{fetch data over the network without}

blocking user interaction with an

activity

• _{Content Provider: DB or other data access}

• _{Broadcast Receiver: responds to system}

messages

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Android UI

• _{UI construction can be done in three}

ways:

• _{Programmatic, like hand-coded Java}

desktop GUI construction

• _{Declarative hand-written, like Java web}

UI construction

• _XML

• _{Declarative with a GUI builder, like .NET}

UI construction

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Programmatic UI

package cs454.demo;

import android.app.Activity;

import android.widget.TextView; import android.os.Bundle;

public class AndroidDemo extends Activity {

/** Called when the activity is frst created. */ @Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

// Activity is a subclass of context, so the TextView takes this as a parameter TextView tv = new TextView(this);

tv.setText("Hello, CS454"); setContentView(tv);

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Manual Declarative

UI

main.xml Layout File:

<?xml version="1.0" encoding="utf-8"?>

<TextView

xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/textview"

android:layout_width="fll_parent"

android:layout_height="fll_parent"

android:text="@string/hello"/>

strings.xml resource fle:

<?xml version="1.0" encoding="utf-8"?>

<string name="hello">Hello Again, CS454!</string>

<string name="app_name">CS454 AndroidDemo</string>

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Manual Declarative

public class AndroidDemo extends Activity {

/** Called when the activity is frst created. */ @Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

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What’s R?

/* AUTO-GENERATED FILE. DO NOT MODIFY. This class was automatically generated by the

* aapt tool from the resource data it found. It should not be modifed by hand. */

package cs454.demo; public fnal class R {

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Android Event

Handlers

From the code fle for the activity:

Button ok = (Button) fndViewById(R.id.button1);

ok.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {

CharSequence s = et.getText(); tv.setText("Welcome, " + s);

(21)

Sams Teach Yourself Android™Application Development in 24 Hours (0321673352)

(22)

APIs for Android built-ins

• _{Android OS ships with many built in apps}

• _{Web Browser}

• _{Google Maps}

• _Navigation

• _{Camera apps}

• _{Built in access for these as well as TTS}

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My Project

• _{Goats and Tigers is a board game, which we}

implemented in Java in CS 460 last term.

• _{The objective in CS460 was to implement the}

minmax / alpha beta pruning algorithm for the automatic player, not to create a good UI

• _{My existing interface shows an ASCII art picture}

of the board and provides a JOptionPane menu of available moves

• _{I will develop an Android UI and use my existing}

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References

•

http://www.ibm.com/developerworks/opensource/library/os-android-devel/

• _{http://developer.android.com/resources/browser.html?}

tag=tutorial

• _{Conder and Darcey, Android Wireless Application}

Development, Addison-Wesley, 2010

• _{Conder and Darcey, Sams Teach Yourself Android}