NotSerializableException while saving fragment state

Question

I'm occasionally seeing exceptions that I do not really understand. Here's what I do: I have an interface

public interface IResultProcessor<T> extends Serializable {

    void processResult(T result);

}

, instances of which I use in this class:

public class ConfirmationDialogFragment extends DialogFragment {

    public static void executeAfterConfirmation(FragmentActivity activity, IResultProcessor<Void> runnable,
        String title, String message, int icon, String positiveButtonText, String negativeButtonText) {

        ConfirmationDialogFragment fragment = new ConfirmationDialogFragment();
        Bundle args = new Bundle();
        args.putSerializable(ARG_RUNNABLE, runnable);
        fragment.setArguments(args);
        fragment.show(activity.getSupportFragmentManager(), "dialog");
    }

}

In the onCreateDialog() method, I receive the IProcessResult instance and execute it if the user has confirmed.

I then use all this in an activity as follows:

@SuppressWarnings("serial") 
IResultProcessor<Void> processor = new IResultProcessor<Void>() {

    @Override
    public void processResult(Void result) {
        new AsyncTask<Void, Void, String>() {

            @Override
            protected String doInBackground(Void... params) {
                DBFacade.INSTANCE.saveSession(session);
                return "My msg...";
            }

            @Override
            protected void onPostExecute(String result) {
                Toast.makeText(MyActivity.this, result, Toast.LENGTH_LONG).show();
            }

        }.execute((Void) null);
    }
};
ConfirmationDialogFragment.executeAfterConfirmation(this, processor, "Save session?", "dialog text", R.drawable.ic_dialog_info, "Save", "Don't save");

The session object saved in the AsyncTask does not implement Serializable (but Parcelable because of other reasons) and is a field of MyActivity.

And here's the exception I'm seeing:

java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = MyActivity$3)
    at android.os.Parcel.writeSerializable(Parcel.java:1279)
    at android.os.Parcel.writeValue(Parcel.java:1233)
    at android.os.Parcel.writeMapInternal(Parcel.java:591)
    at android.os.Bundle.writeToParcel(Bundle.java:1619)
    at android.os.Parcel.writeBundle(Parcel.java:605)
    at android.support.v4.app.FragmentState.writeToParcel(Fragment.java:132)
    at android.os.Parcel.writeTypedArray(Parcel.java:1102)
    at android.support.v4.app.FragmentManagerState.writeToParcel(FragmentManager.java:357)
    at android.os.Parcel.writeParcelable(Parcel.java:1254)
    at android.os.Parcel.writeValue(Parcel.java:1173)
    at android.os.Parcel.writeMapInternal(Parcel.java:591)
    at android.os.Bundle.writeToParcel(Bundle.java:1619)
    at android.os.Parcel.writeBundle(Parcel.java:605)
    at android.app.ActivityManagerProxy.activityStopped(ActivityManagerNative.java:2078)
    at android.app.ActivityThread$StopInfo.run(ActivityThread.java:2874)
    at android.os.Handler.handleCallback(Handler.java:615)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4745)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.io.NotSerializableException: MyActivity
    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1364)
    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
    at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:979)
    at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:368)
    at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1074)
    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1404)
    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
    at android.os.Parcel.writeSerializable(Parcel.java:1274)
    ... 23 more
java.io.NotSerializableException: MyActivity
    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1364)
    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
    at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:979)
    at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:368)
    at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1074)
    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1404)
    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
    at android.os.Parcel.writeSerializable(Parcel.java:1274)
    at android.os.Parcel.writeValue(Parcel.java:1233)
    at android.os.Parcel.writeMapInternal(Parcel.java:591)
    at android.os.Bundle.writeToParcel(Bundle.java:1619)
    at android.os.Parcel.writeBundle(Parcel.java:605)
    at android.support.v4.app.FragmentState.writeToParcel(Fragment.java:132)
    at android.os.Parcel.writeTypedArray(Parcel.java:1102)
    at android.support.v4.app.FragmentManagerState.writeToParcel(FragmentManager.java:357)
    at android.os.Parcel.writeParcelable(Parcel.java:1254)
    at android.os.Parcel.writeValue(Parcel.java:1173)
    at android.os.Parcel.writeMapInternal(Parcel.java:591)
    at android.os.Bundle.writeToParcel(Bundle.java:1619)
    at android.os.Parcel.writeBundle(Parcel.java:605)
    at android.app.ActivityManagerProxy.activityStopped(ActivityManagerNative.java:2078)
    at android.app.ActivityThread$StopInfo.run(ActivityThread.java:2874)
    at android.os.Handler.handleCallback(Handler.java:615)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4745)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
    at dalvik.system.NativeStart.main(Native Method)

Any idea what's going on here?

Answer 1

I haven't totally understood, but apparently solved the issue. The exceptions were thrown when the activity was destroyed because another one came into the foreground. I solved it by converting the anonymous IResultProcessor class into a static inner class of my activity.