Adobe AIR 3.1 Native Extension for Android - null extension context in actionscript

Question

I'm working on Native Extension for Android platform and i got stuck...

Targeting Android 2.1... testing on Google Nexus One (2.3.6)

this line returns NULL

this.context = ExtensionContext.createExtensionContext("com.company.ane.LocationManager", "");

this is extension descriptor file:

<extension xmlns="http://ns.adobe.com/air/extension/3.1">
<id>com.company.ane.LocationManager</id>
<versionNumber>0.0.1</versionNumber>
<platforms>
<platform name="iPhone-ARM">
  <applicationDeployment>
    <nativeLibrary>libANELocationManager.a</nativeLibrary>
    <initializer>ExtInitializer</initializer>
    <finalizer>ExtFinalizer</finalizer>
  </applicationDeployment>
</platform>
<platform name="Android-ARM">
<applicationDeployment>         
   <nativeLibrary>libANELocationManager.jar</nativeLibrary>
     <initializer>com.company.ane.android.ANELocationManager</initializer>
</applicationDeployment> 
       </platform></platforms></extension>

that is my package command:

adt -package -target ane ./../../app/libs/locationmanager.ane ./../extension.xml -swc ane_location_manager.swc -platform iPhone-ARM library.swf libANELocationManager.a -platform Android-ARM library.swf libANELocationManager.jar

At this stage extension is really simple... i'm just trying to return string value back to my app...

package com.company.ane.android;

import java.util.HashMap;
import java.util.Map;

import com.adobe.fre.FREContext;
import com.adobe.fre.FREFunction;

import android.location.LocationListener;
import android.location.LocationManager;

public class ANELocationManagerContext extends FREContext {

public LocationManager locationManager;
public LocationListener locationListener;

@Override
public void dispose() {
    // TODO Auto-generated method stub

}

@Override
public Map<String, FREFunction> getFunctions() {

    Map<String, FREFunction> functionMap = new HashMap<String, FREFunction>();

    functionMap.put("ExtensionTest", new ExtensionTest());

    return functionMap;
}

    }


 package com.company.ane.android;

import com.adobe.fre.FREContext;
import com.adobe.fre.FREFunction;
import com.adobe.fre.FREObject;
import com.adobe.fre.FREWrongThreadException;

public class ExtensionTest implements FREFunction {

@Override
public FREObject call(FREContext context, FREObject[] args) {

    FREObject result = null;
    //ANELocationManagerContext ctx = (ANELocationManagerContext) context;


    try 
    {
        result  = FREObject.newObject("It works!");  

    }
    catch (FREWrongThreadException fwte)
    {
        fwte.printStackTrace();
    }

    return result;
}

 }


package com.company.ane.android;

import com.adobe.fre.FREContext;
import com.adobe.fre.FREExtension;

public class ANELocationManager implements FREExtension {

@Override
public FREContext createContext(String contextType) {

    return new ANELocationManagerContext();
}

@Override
public void dispose() {
    // TODO Auto-generated method stub

}

@Override
public void initialize() {
    // TODO Auto-generated method stub

}

}

Answer 1

Where are you getting the NULL reference? Is this running on device or in the AIR simulator?

If ExtensionContext can not be found for the current platform you are running on (eg: windows simulator) NULL is returned, even though it might run fine on the device. You can setup a default context when compiling the ANE that would be used where ever specific match is not found. This default target can be written entirely in AS3, and is useful for faking or handling unsupported devices.

The Adobe AIR documentation has more details on including a default implementation. See here: http://help.adobe.com/en_US/air/extensions/WSf268776665d7970d-2482335412ffea65006-8000.html

EDIT: Whoops, I see you are running on device. I'd still try a default one and see if you can get that working, it might help narrow down the problem.

EDIT 2: Are you Implementing the FREExtension interface (in Java)? I don't see that in your posted code.

Answer 2

The most basic extension still includes 2 classes.

You need to implement the FREExtension interface:

package com.your.package;

import com.adobe.fre.FREContext;
import com.adobe.fre.FREExtension;

public class YourExtension implements FREExtension 
{
public static FREContext context;

@Override
public FREContext createContext(String contextType) 
{
    return context = new YourContext();
}

@Override
public void dispose() 
{
    context = null;
}

@Override
public void initialize() 
{
}
}

And then the context is the class you have above:

package com.your.package;

import java.util.HashMap;
import java.util.Map;

import com.adobe.fre.FREContext;
import com.adobe.fre.FREFunction;

public class YourContext extends FREContext 
{
@Override
public void dispose() 
{
}

@Override
public Map<String, FREFunction> getFunctions() 
{
    Map<String, FREFunction> functionMap = new HashMap<String, FREFunction>();
    // Create your map      
    return functionMap;
}
}

The class in the extension xml should be the first one here, i.e. the FREExtension implementation.

Also unless you are creating the iPhone version of this extension you should remove the iPhone node from your extension.xml.

Answer 3

I had exactly same issue. My ANE was working fine on iOS, on simulator, with default lib used, but wasn't working on actual Android device (Android-ARM platform).

And ExtensionContext.createExtensionContext() was returning null.

It turned out that this problem is tools version problem, Java compiler version. I was using latest AIR (3.8), JDK (1.7.25), Android SDK (22.0.5) etc. It didn't work.

But after adding -target 1.6 to javac call, it worked well.

Answer 4

I did get the same problem before and actually the problem was not the createExtensionContext() function itself but the class FREContext and most of the time it happend in the method public Map getFunctions()

Basically, for example I have declared 3 FREFunctions to use in my FREContext like :

functionMap.put("initMe", new initFunction() );
functionMap.put("getVersion", new getVersion() );
functionMap.put("showBrowser", new showBrowser() ); // For example, I got some exceptions in this function as I declare some Java variable that is not supported by the current Android SDK version like LocationManager (for example)

So when the FREContext is initialized, this class will goes through the constructor of each function inside and if I got some exceptions somewhere in the constructor of getVersion() function, the FREContext will crash and return null back to createExtensionContext(). The solution to this problem is if you are not sure where you get the exception, comment out all your FREFunction one by one to figure out which one cause the exception. In your case, I doubt the 2 variables

  public LocationManager locationManager;
  public LocationListener locationListener;

are the causes of the Exception. Please comment them out and try again. Another thing that can help you a lot when building the ANE is trying to debug the ANE from your ADT by attach the current AIR android app's port to ADT's debugger. You can learn more about how to debug ANE from this article http://www.adobe.com/devnet/air/articles/ane-android-devices.html

Hope it helps.

Answer 5

I ran into the same problem when trying to build ANE-Video:

_context = ExtensionContext.createExtensionContext(EXTENSION_ID, null);

// _context is set to null, with no other error info

I solved the problem by compiling with a 1.6 JDK instead of a 1.7 JDK (running on Mac OS X Mavericks).

This post helped temporarily roll the JDK back to 1.6.

The clue came from this Adobe article:

At this point Adobe tooling is not quite compatible with Java 7 and you may run into errors at linking and packaging time.