Apache Felix - Using a bundle service shows "java.lang.ClassCastException"

Question

I am embedding Apache Felix into an Android application. In that application, I am trying to use a service provided by a bundle. The bundle is successfully installed and started, but at the line that uses the service which is:

 System.out.println( ((AndroidService) services [0]).startActivity());

I get the following error:

 java.lang.ClassCastException: androidapi_bundle.AndroidServiceImpl cannot be cast to com.example.android_services.AndroidService

I have the following in my bundle:

1- Activator class

package androidapi_bundle;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import com.example.android_services.AndroidService;
import android.util.Log;


public class Activator implements BundleActivator {

    private static BundleContext context;

    static BundleContext getContext() {
        return context;
    }


    public void start(BundleContext bundleContext) throws Exception {
        Activator.context = bundleContext;

        System.out.println("This is a java message inside the start method of AndroidAPI_Bundle");
        Log.d("Zitona Log","This is android message inside the start method of AndroidAPI_Bundle");


        context.registerService(
                AndroidService.class.getName(), new AndroidServiceImpl(),null);
    }


    public void stop(BundleContext bundleContext) throws Exception {
        Activator.context = null;

        Log.d("Zitona Log","AndroidAPI_Bundle stopped!");
    }

}

2- com.example.android_services which has AndroidService.java interface:

package com.example.android_services;

public interface AndroidService {

    public String startActivity();


}

3- its implementation class AndroidServiceImpl.java :

package androidapi_bundle;

import com.example.android_services.*;

public class AndroidServiceImpl implements AndroidService {

    @Override
    public String startActivity()
    {
        return "Activity started";

    }


}

Now, in my android app I also have AndroidService.java interface, and the following is the code that uses the service:

@SuppressWarnings({ "rawtypes", "unchecked" })

ServiceTracker m_tracker = new ServiceTracker(
        m_activator.getContext(),AndroidService.class.getName(), null);

    m_tracker.open();

    System.out.println("8");

    Object[] services = m_tracker.getServices();

    System.out.println("9");
    System.out.println( ((AndroidService) services [0]).startActivity());


   System.out.println("10");

After "9" is displayed I get the error. Where did I go wrong?

Below is my bundle MANIFEST:

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: AndroidAPI_Bundle
Bundle-SymbolicName: AndroidAPI_Bundle
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: androidapi_bundle.Activator
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Import-Package: org.osgi.framework;version="1.3.0", android.util, com.example.android_services
Export-Package: com.example.android_services

Update:

I realized that I have this line of code:

   m_configMap.put(FelixConstants.FRAMEWORK_SYSTEMCAPABILITIES_EXTRA, "com.example.android_services");

so I changed it to:

    m_configMap.put(FelixConstants.FRAMEWORK_SYSTEMPACKAGES_EXTRA, "com.example.android_services");

Now I am getting this error:

 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.apache_felix_android/com.example.apache_felix_android.MainActivity}: java.lang.NullPointerException

Answer 1

The only way you can get this is if both the activator bundle and the app bundle have an internal copy of the service class and neither exports it. So you will need to show your manifests and bundle contents.

Update What on earth are you mucking with advanced options like system packages (and then using Felix classes instead of OSGi's constant class) when you seem to have very basic problems. Why not start with a clean simple bndtools, make your app work in there using an IDE, and then when it works port it to Android? This all looks awfully masochistic way to learn OSGi?