This document discusses an Android GUI project. It provides an overview of Android basics, development, and UI. Key points include: - Android uses Linux kernel, apps written in Java and run on Dalvik VM. - Standard development environment is Eclipse + Android SDK + emulator or device. - The project will develop an Android UI for an existing Goats and Tigers board game implementation, reusing backend code.

1. Android GUI Project
John Hurley
CS 454

2. Android
• 1. Android Basics
• 2. Android Development
• 3. Android UI
• 4. Hello, World
• 5. My Project

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 performance.

4. 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.

5. Android Development
• Well-defined 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
• I will give examples when I find out!

6. 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

7. 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

8. 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.
• Probably better performance; one layer less

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 sources”

10. 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?

11. Android Deployment
• Apps are packaged in .apk format, variant of .jar,
then downloaded to device and installed
• .apks contain .dex files (bytecode), manifest and
various other files
• Manifest contains security and link info,
hardware access info, minimum OS release info,
etc.

12. 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

13. Android UI
• Service: background operation
• play music in the background while the user is in
a different 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
• Battery low

14. 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
• GUI builder generates the XML

15. 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 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);
}
}

16. 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="fill_parent"
android:layout_height="fill_parent"
android:text="@string/hello"/>
strings.xml resource file:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello">Hello Again, CS454!</string>
<string name="app_name">CS454 AndroidDemo</string>
</resources>

17. Manual Declarative UI
Java class:
package cs454.demo;
import android.app.Activity;
import android.os.Bundle;
public class AndroidDemo extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}

18. 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;
}

19. UI With GUI Builder

20. Android Event Handlers
From the code file for the activity:
Button ok = (Button) findViewById(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)
Copyright ©2010 Lauren Darcey and Shane Conder
FIGURE 3.2 Important callback methods of the activity life cycle.

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 and Voice
Recognition, etc.

23. Demo

24. 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

25. 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 Application
Development in 24 Hours, Sams, 2010