Tech Talk Project Work

1
Tech Talk
AndroidWrapper for JamaicaVM
Antonio Cesarano,
aicas GmbH
9 September 2013

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Agenda
– Goal
– Issues
– Structure of Android applications
– Incompatibilities with JamaicaVM
– Proposed solution
– AndroidWrapper

3
Goal
Execute the source code of Android applications on the
JamaicaVM.
Goal

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Main question
– Why is not already possible?
Android applications are based on Java but they use own
APIs, that are not compilable by JamaicaVM.
javax.swing.JCompone
nt android.view.View
?
Issues

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Java code execution
– Windows, Linux and other OS
HARDWARE
(Intel, AMD, ARM)
Operating System
(Windows, Linux, QNX)
Jamaica Runtime Environment
Java API
Class
Jamaica
Virtual
Machine
public class Hello
{
   public static void main(String
args[])
   {
      System.out.println(“Hello World”);
   }
}
Issues

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Java code execution
– Android
HARDWARE
(Intel, ARM)
Linux Kernel
Android API
Class
Dalvik
Virtual
Machine
public class MainActivity extends Activity
{
    @Override
    protected void onCreate(Bundle bundle)
    {
        super.onCreate(savedInstanceState);
        TextView textView = (TextView)
findViewById(R.id.textView1);
        textView.setText("Hello World");
    }
}
Android Runtime Environment
Issues

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Android applications
Main components
– activity_main.xml
– R.java
– MainActivity.java
Structure of Android Application

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activity_main.xml
<LinearLayout

xmlns:tools="http://schemas.android.com/tools
"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
>
     <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/hello_world"
      />
</LinearLayout>
Simple example

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activity_main.xml
<LinearLayout

xmlns:tools="http://schemas.android.com/tools
"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
>
     <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/hello_world"
      />
</LinearLayout>
Simple example

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R.java
public final class R {
public static final class id {
        public static final int textView1=0x7f080000;
    }
    public static final class layout {
        public static final int activity_main=0x7f030000;
    }
}
The R.java file is auto-generated by the Android Resource Manager and
contains references to all resources of the app.

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MainActivity.java
{
    protected void onCreate(Bundle bundle) {
        super.onCreate(bundle);
        TextView
textView=(TextView)findViewById(R.id.textView1);
        textView.setText("Hello, World!");
    }
}
Hello World example:

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Some incompatibilities to solve
Incompatibilities with JamaicaVM

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Incompatibilities - 1
javax.swing
java.awt
java.tools
java.rmi
...
java.io
java.tools
java.util
java.lang
android.app
android.graphics
android.os
android.content
Android API
Jamaica API

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public static void main(String args[])

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Graphics components are not created in the source code but are
declared in the activity_main.xml file.

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Proposed Solution
Adapter Design Pattern
– Adapter pattern (also known as Wrapper) allows classes that normally
could not work together, because of incompatible interfaces, to work
together.
Proposed Solution

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Different APIs
android.app
android.graphics
android.os
android.content
Android API
...
Adaptee classes
android.app
android.graphics
...
Proposed Solution
Android classes for JamaicaRE

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main() method non-existent
Wrapper
onCreate()
{
  doSomething();
}
Android code
public static void main()
     {
        onCreate();
     }
Adaptee classes
android.app
android.view
...
Proposed Solution

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Get graphic components from XML file
1 - Parse the xml file
2 – Map objects into graphic components
3 – Draw graphic components
1
3
1
2
Proposed Solution

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Android Wrapper
XML Parser
●TreeGraphicNode
●GraphicNodeParser
Graphic manager
●GraphicDrawer
Wrapper
●Activity
●AndroidWrapper
Adaptee classes
AndroidWrapper Solution

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TreeGraphicNode
String androidID
String graphicElement
String marginLeft
...
...
List<TreeGraphicNode>
TreeGraphicNode
Attributes
Children
Parent
AndroidWrapper Solution – XML Parser

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GraphicNodeParser
Linear
Layout
Edit
Text
Button Radio
Group
Radio
Button
Radio
Button
DOM parent = null;
AndroidID = layout1;
GraphicElement = LinearLayout;
Children = 0x7fff9465a02f;
Parent = 0x7fff9575c05f;
AndroidID = text1;
GraphicElement = TextView;
Children = null;
AndroidID = button1;
GraphicElement = Button;
Children = null;
AndroidID = group1;
GraphicElement = RadioGroup;
Children = 0x7fff4711b09f;
Parent = 0x7fff2311d01f,
AndroidID = radio1;
GraphicElement = RadioButton;
Children = null;
Parent = 0x7fff2311d01f;
AndroidID = radio2;
Children = null;
AndroidWrapper Solution – XML Parser
What it does?
● Create an instance of TreeGraphicnode from the DOM

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Android Wrapper
XML Parser
●TreeGraphicNode
Graphic manager
●GraphicDrawer
Wrapper
●Activity
●AndroidWrapper
Adaptee classes

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GraphicDrawer
Twomain tasks:
1. Createthescreen surface
2. Draw graphic componentsinto thescreen
AndroidWrapper solution - Graphic manager

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Create the screen surface
➢ Createthemain frame
➢ Createthecommand panel
➢ Createtheactivity panel
MainFrame
CommandPanel
ActivityPanel

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Draw graphic components into the screen
Two phases:
➢Draw graphic components written in the xml
➢Add components to the screen

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Draw components
parent = null;
AndroidID = text1;
GraphicElement = TextView;
Children = null;
AndroidID = button1;
GraphicElement = Button;
Children = null;
AndroidID = group1;
GraphicElement = RadioGroup;
Children = 0x7fff4711b09f;
Parent = 0x7fff2311d01f,
AndroidID = radio1;
Children = null;
Parent = 0x7fff2311d01f;
AndroidID = radio2;
Children = null;
button1button1
radio1
radio2
group1
text1
layout1
drawComponent(nod
e)
Graphic manager – Draw components into the screen
Key
layout1
text1
button1
group1
radio1
radio2
Value
componentsMap

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Add components to the screen
parent = null;
Key
layout1
text1
button1
group1
radio1
radio2
Value
componentsMap
layout1
layout1
Graphic manager – Draw components into the screen

29
Android Wrapper
XML Parser
●TreeGraphicNode
Graphic manager
●GraphicDrawer
Wrapper
●Activity
●AndroidWrapperer
Adaptee classes
AndroidWrapper solution

30
MainActivity.java
{
    protected void onCreate(Bundle bundle) {
        super.onCreate(bundle);
        TextView
textView=(TextView)findViewById(R.id.textView1);
        textView.setText("Hello World");
    }
}
Hello World example:
AndroidWrapper solution - Wrapper

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Activity
The Activity adaptee class is responsible to instantiate a
GraphicDrawer and get the graphic from it.
{
graphicDrawer = new GraphicDrawer(bundle);
graphicDrawer.generateGraphic();
}
layout1
button1button1
radio1
radio2
text1
group1

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AndroidWrapper
Two simple tasks:
1. Class R =
Class mainActivity =
File xmlFile  =
R.java
activity_main.xml
MainActivity.java
2. public static void main(String arg[])
   {
     mainActivity.onCreate(new
Bundle(R,xmlFile))
   }

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Android Wrapper
XML Parser
●TreeGraphicNode
Graphic manager
●GraphicDrawer
Wrapper
●Activity
●AndroidWrapper
Adaptee classes

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Adaptee classes
To work correctly, the Adapter must find the JamaicaVM version of the
classes requested by the MainActivity.
JamaicaRE
android.app.Activity
android.widget.TextView
...
MainActivity.java
import android.app.Activity;
import android.widget.TextView;
....
public void onCreate()
{
......
.....
}
.....

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Adaptee classes
Solution:
– Write all Android classes ad-hoc for JamaicaVM
Positive aspect Negative aspect

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Positive aspect
Maximum compatibility with JamaicaVM
– Classes written ad-hoc for JamaivcaVM

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Negative aspect
Reproduce the whole Android Runtime Environment:
● The number of the classes is very enormous
● The complexity is not always low
AndroidWrapper solution – Adaptee classes

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– not always:
Three scenarios:
1) Need to write the class from zero
2) Wrap the class with an equivalent one
3) Use the original class
Adaptee classes - complexity

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Mercury
Adaptee classes
1) Write a class from zero
Example: android.widget.ListView
Venus
Earth
Mars
....
JPanel JScrollBar
JLabel

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Adaptee classes
2) Wrap the class with an equivalent one
Example: android.widget.Button
public Class Button extends
JButton
{
   public Button(String text)
   {
      super(text);
   }
   ....
}

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Adaptee classes
3) Use the original class
- When Android classes use only objects of Java
e.g android.util.TextUtils
javax.swing
java.awt
java.tools
java.rmi
...
java.io
java.tools
java.util
java.lang
android.app
android.graphics
android.os
android.content
Android API
Java API

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Summary: full route

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Adaptee classes
Complexity for reproduce the whole Android Runtime Environment
Complexity
Activity
Classes
Textutils Button TextView
low
medium
high
Parcelable Resources
Use original class
Wrap with equivalent class
Write from zero
average
complexity
...

48
Sequence diagram

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