Android GUI project slide

Sams Teach Yourself Android™Application Development in 24 Hours 0321673352Copyright ©2010 Lauren Darcey and Shane Conder FIGURE 5.6 Simplified Android platform architecture from a securi

Android GUI Project

John Hurley

CS 454

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 performance

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

Copyright ©2010 Lauren Darcey and Shane Conder

FIGURE 5.6 Simplified Android platform architecture from a security perspective.

Android Development

other parts of the Java platform are missing

libraries are not included

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 affected by specific hardware and software

configuration

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 first 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 free even for

commercial use, unlike Visual Studio

Android App vs Mobile- Optimized RIA

• Android Flash plugins available; Silverlight coming soon

• Could develop in JavaScript and/or HTML5

• 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

• Probably better performance; one layer less

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 sources”

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

• Sell to companies?

Android Deployment

then downloaded to device and installed

various other files

hardware access info, minimum OS release info, etc

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 objects in

the UI

Android UI

a different application

user interaction with an activity

Android UI

public class AndroidDemo extends Activity {

/** Called when the activity is first 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);

}

}

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"

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

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

</resources>

public class AndroidDemo extends Activity {

/** Called when the activity is first created */

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 modified by hand */

package cs454.demo;

public final class R {

public static final class attr {

}

public static final class drawable {

public static final int icon=0x7f020000;

}

public static final class id {

public static final int textview=0x7f050000;

}

public static final class layout {

public static final int main=0x7f030000;

}

public static final class string {

public static final int app_name=0x7f040001;

public static final int hello=0x7f040000;

}

}

UI With GUI Builder

Android Event Handlers

From the code file for the activity:

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

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

Copyright ©2010 Lauren Darcey and Shane Conder

FIGURE 3.2 Important callback methods of the activity life cycle.

APIs for Android built-ins

Demo

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 backend

code as much as possible

• Conder and Darcey, Sams Teach Yourself Android Application

Development in 24 Hours, Sams, 2010