1. Java Micro Edition Platform
&
Android
Seminar on Small and Mobile Devices
May 13th, 2008
Dejan Juric (djuric@student.ethz.ch)
May 13th, 2008 Seminar on Small and Mobile Devices
Dejan Juric (djuric@student.ethz.ch) 1

2. Outline
● Motivation & Goal
● Java Micro Edition Platform
● Android
● Java ME vs Android
● Conclusion & Discussion
May 13th, 2008 Seminar on Small and Mobile Devices
Dejan Juric (djuric@student.ethz.ch) 2

3. Motivation
● Number of mobile phone subscribers by
November 2007: 3.3 billion. (personal
computers: 1 billion)
● Problems with mobile devices:
– Heterogeneous: different form factors, features,
functions
– Resource­constrained
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4. Goal
● Allow customization of devices
– Download new services and applications from the
Internet
● Development of applications and services
– Device­independent
– Cost efficient
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5. Java Micro Edition Platform
● Available on most current mobile phones
● Subset of the Java Platform
– for resource­constrained devices
Java ME
Java SE
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6. Java Platforms
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7. Java Micro Edition ­ Overview
Profiles
Configurations
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8. Java ME ­ Configurations
● Configuration:
complete Java
runtime environment
– Defines the minimum
set of Java virtual
machine features &
class libraries
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9. Java ME – Configurations ­ CDC
● Connected Device
Configuration
– 32bit CPU, 2MB of
RAM, 2 MB of ROM
– Modified Java SE core
class libraries
– CDC 1.1 matches JDK
1.4 APIs
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10. Java ME – Configurations ­ CLDC
● Connected Limited
Device Configuration
– At least 160 kB of
non­volatile memory
– At least 32 kB of
volatile memory
– Minimal host CLDC 1.1
java.lang
operating system or +java.lang.ref
kernel available java.io
java.util
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11. Java ME – CLDC
● Eliminated features
– User­defined class loaders
– Thread groups and daemon threads
– Finalization of class instances
– Asynchronous exceptions
– Floating point types (since CLDC 1.1)
● Class file verification
– Off­device preverification and runtime verification
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12. Java ME ­ Profiles
● Define a minimum set
of APIs available on a
“family” of devices
● Applications are
written for a particular
profile
– Portable across
devices that support
that profile
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13. Java ME ­ MIDP
● Mobile Information Device Profile
– Screen of at least 96x54 pixels
– Keypad, keyboard or touchscreen input
– 256 KB of nonvolatile memory
– 128 KB of RAM
– 8 KB of nonvolatile writable memory for persistent
data
– Two­way network connection
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14. Java ME ­ MIDP
● Mobile Information Device Profile – Building
Blocks
CLDC 1.1 MIDP 2.0
java.lang javax.microedition.lcdui
+java.lang.ref +javax.microedition.lcdui.game
java.io +javax.microedition.media
java.util +javax.microedition.media.control
javax.microedition.io javax.microedition.midlet
+javax.microedition.pki
javax.microedition.rms
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15. Java ME – Development Process
Java Source
Compile
Java Class Files Application on Device
Preverification Deployment
Preverified Class Files JAR Package
Packaging
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16. Java ME – Development Tools
● Wireless toolkits:
– Sun Wireless Toolkits
– Motorola SDK for J2ME™
– Sony Ericsson J2ME SDK
● Development Environments
– EclipseME
– Netbeans Mobility
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17. Java ME – MIDlet Demo
// Exceptions omitted for clarity
public class TestMIDlet extends MIDlet implements CommandListener {
private Form mMainForm;
public TestMIDlet() {
mMainForm = new Form("TestMIDlet");
mMainForm.append(new StringItem(null, "Hello, MIDP!"));
mMainForm.addCommand(new Command("Exit", Command.EXIT, 0));
mMainForm.setCommandListener(this);
}
protected void destroyApp(boolean arg0) {
}
protected void pauseApp() {
}
protected void startApp() {
Display.getDisplay(this).setCurrent(mMainForm);
}
public void commandAction(Command arg0, Displayable arg1) {
notifyDestroyed();
}
}
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18. Java Micro Edition
● Questions?
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19. Android
● Software platform and
operating system for
mobile devices based
on the Linux
operating system
● Developed by Google
and the Open
Handset Alliance
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20. Android ­ Open Handset Alliance
● Vision: “... accelerate innovation in mobile and
offer consumers a richer, less expensive, and
better mobile experience.”
● Members (more than 30):
– Google, HTC, NTT DoCoMo, China Mobile, T­
Mobile, Motorola, Samsung, Intel ...
– Swiss members: Esmertec, Noser
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21. Android ­ Architecture
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22. Android ­ Runtime
● Dalvik: It's not a Java virtual machine
● Every Android application runs in its own
process within its own instance of the Dalvik
VM.
javac
Java Source Java Class Files
dx
Dalvik Executable
Files (.dex)
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23. Android – Application Framework
● Views: User Interface
● Content Providers: Access & share data
● Resource Manager: non­code resources
(graphics, external strings ...)
● Notification Manager: custom alerts in status
bar
● Activity Manager: Manages life cycle of
applications
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24. Android – Activity & Intent
● Activity: single, focused thing that the user can
do
● Intent: abstract description of an operation to be
performed
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25. Android – Life cycle ­ Activity
● Activity can be killed!
● We have to store the
state
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26. Android ­ Development
● Software Development Kit:
– Eclipse Plugin
– Command line tools
● Dalvik Debug Monitor Service (ddms)
● Android Debug Bridge (adb)
● Android Asset Packaging Tool (aapt)
● Android Interface Description Language (aidl)
– Emulator
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27. Android ­ Demo
● Demonstration with SDK and emulator
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28. JavaME vs Android – Developer's
Perspective
● Java ME ● Android
+ Security model + Security model
+ Works on many + Optimized for
devices smartphones
­ On mobile phones: + Seamless integration
Integration into into system
system not seamless ­ API: more complicated
­ Too many APIs than Java ME
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29. Java ME vs. Android ­ General
● Java ME ● Android
+ Lots of devices + Opensource
already available + Defines unique
­ Fully controlled by Sun software stack for
(Licensing!) mobile devices
­ Formal specification ­ No devices available
process (slow) ­ No standards are used
(e.g. VM, IDL ...)
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30. Conclusions
● Rapid growth in the mobile market expected
● Wireless devices getting more powerful
– More features
– Better connectivity
● Both technologies could play a big role in the
future
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31. Discussion
● Questions?
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