DP5 7.0 - Does adding extras to a pending intent fail?

Question

Adding the linked issue on tracker: https://code.google.com/p/android/issues/detail?id=216581&thanks=216581&ts=1468962325

So I installed the DP5 Android 7.0 release onto my Nexus 5X today. I've been working on an app that schedules local notifications at specific times using Android's AlarmManager class. Up until this release, the code has been working great on devices running KitKat, Lollipop, and Marshmallow.

Below is how I'm scheduling the alarms:

Intent intent = new Intent(context, AlarmManagerUtil.class);
            intent.setAction(AlarmManagerUtil.SET_NOTIFICATION_INTENT);
            intent.putExtra(AlarmManagerUtil.REMINDER_EXTRA, Parcels.wrap(reminders));
            intent.putExtra("time", when.getMillis());
            PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
            if (alarmManager != null) {
                if (Build.VERSION.SDK_INT >= 23) {
                  alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, when.getMillis(), pendingIntent);
                } else if (Build.VERSION.SDK_INT >= 19) {
                    alarmManager.setExact(AlarmManager.RTC_WAKEUP, when.getMillis(), pendingIntent);
                } else {
                    alarmManager.set(AlarmManager.RTC_WAKEUP, when.getMillis(), pendingIntent);
                }

My AlarmManagerUtil @onReceive of the "SET_NOTIFICATION_INTENT" looks like this:

public void fireNotification(Context context, Intent intent) {
    List<Reminder> reminderToFire = Parcels.unwrap(intent.getParcelableExtra(REMINDER_EXTRA));
    long timeToFire = intent.getLongExtra("time", 0L); //.... }

What's strange is the "reminderToFire" is null here only on Android N devices but the timeToFire is correct.

I'm thinking its something to do with the Parceler Library? I'm compiling using Java 1.8 and targeting Android API 24.

I've definitely looked around the net for an answer to this, but my case is a bit unique since the code 100% works on all prior versions of Android (everything below N preview)...so I am following the below answers as much as I can:

How can I correctly pass unique extras to a pending intent?

Anybody else have this issue?

Caine

Have you looked to see if Parcels.wrap(reminders) is returning null? Have you looked to see if intent.getParcelableExtra(REMINDER_EXTRA) is returning null, before you pass that value to Parcels.unwrap()? Have you tried stuffing some other Parcelable into the Intent to see if it survives the trip (e.g., a Point)? – Hypno

@Hypno the Intent being passed into the PendingIntent argument above is being loaded with the mExtras object with mMap containing two objects, the Long timeToFire and the Parceled reminder object. Upon unwrap in the AlarmManager onReceive, the Long is valid but the reminder object is null. I'll try to Parcel some other object like a Point and see how it goes. Reminder is correctly configured with @Parcel – Caine

"Upon unwrap in the AlarmManager onReceive, the Long is valid but the reminder object is null" -- but, is intent.getParcelableExtra(REMINDER_EXTRA) null? That would indicate the value is getting lost. If intent.getParcelableExtra(REMINDER_EXTRA) is not null, but Parcels.unwrap(intent.getParcelableExtra(REMINDER_EXTRA)) is null, that suggests that Parcels is having difficulty restoring the objects. – Hypno

@Hypno ah, no intent.getParcelableExtra(REMINDER_EXTRA) correctly has the data; however, the mExtras object within the intent is missing the mMap object until it attempts to get the extras. Debugging now, it actually looks like unwrap is getting called with a Parcelable input = null and therefore returns null. This is not the case with devices running prior versions of Android...I'll open an issue with the Parceler library on Github. Thank you sir. – Caine

"it actually looks like unwrap is getting called with a Parcelable input = null and therefore returns null" -- I am confused as to how this meshes with "intent.getParcelableExtra(REMINDER_EXTRA) correctly has the data". – Hypno

@Hypno Ah, I mean intent.getParcelableExtra(REMINDER_EXTRA) is null and thus Parcels.unwrap(null) returns null, but the intent.getAction() correctly displays and the intent.getLong() is correct as well. Sorry. You're correct. The issue seems to lie between the Intent getting set and the BroadcastReceiver onReceive, even though Parcels.wrap(reminder) successfully Parcels the object for the Intent. – Caine

I'm having the same issue but I get nulls returned from both getString and getParcelableArrayList. I didn't see your posting before I posted mine. - see #38775785 – Bouquet

Answer 1

For anyone ending up here pulling your hair out over AlarmManager (and haven't given up and gone to JobScheduler yet), Google in the production API 24 build does not support passing a Parcelable object into the AlarmManager.

The way I got around this: If you need to send a List (or single object) into the AlarmManager, store the item into SharedPreferences as a String. (Gson.toJson(object, type)) If the object is an interface, there are a number of interface adapter solutions out there. One I found floating around S/O:

public final class InterfaceAdapter<T> implements JsonSerializer<T>, JsonDeserializer<T> {

public JsonElement serialize(T object, Type interfaceType, JsonSerializationContext context) {
    final JsonObject wrapper = new JsonObject();
    wrapper.addProperty("type", object.getClass().getName());
    wrapper.add("data", context.serialize(object));
    return wrapper;
}

public T deserialize(JsonElement elem, Type interfaceType, JsonDeserializationContext context) throws JsonParseException {
    final JsonObject wrapper = (JsonObject) elem;
    final JsonElement typeName = get(wrapper, "type");
    final JsonElement data = get(wrapper, "data");
    final Type actualType = typeForName(typeName);
    return context.deserialize(data, actualType);
}

private Type typeForName(final JsonElement typeElem) {
    try {
        return Class.forName(typeElem.getAsString());
    } catch (ClassNotFoundException e) {
        throw new JsonParseException(e);
    }
}

private JsonElement get(final JsonObject wrapper, String memberName) {
    final JsonElement elem = wrapper.get(memberName);
    if (elem == null)
        throw new JsonParseException("no '" + memberName + "' member found in what was expected to be an interface wrapper");
    return elem;
}
}

Once you have the adapter set up, you won't need to set up GS0N each time with the TypeAdapter if you're using some sort of DI framework (i.e. Dagger2) like so...

@Singleton
@Provides
public Gson providesGson() {
    return new GsonBuilder()
            .registerTypeAdapter(YourInterfaceClass.class, new InterfaceAdapter<YourInterfaceClass>())
            .create();

So all you'll have to do is run....

/**
 * stores yourInterfaceClass in shared prefs
 */
public void setNextReminder(List<YourInterfaceClass> yourInterfaceClass) {
    Type type = new TypeToken<List<YourInterfaceClass>>() {}.getType();
    sharedPrefs.edit().putString(YOUR_KEY, gson.toJson(yourInterfaceClass, type)).apply();
}

Hope this helps. Of course, when you need to get this object out of shared prefs....

String json = sharedPrefs.getString(YOUR_KEY, "No object found");

Doing the typical List object = gson.fromJson(json, type) should work.

Cheers.

Caine

A probably-faster approach would be to convert the Parcelable to a byte[], which somebody pointed out to me when I blogged about this issue. See https://mcmap.net/q/275421/-how-to-marshall-and-unmarshall-a-parcelable-to-a-byte-array-with-help-of-parcel for a sample implementation. – Hypno

@CommonsWare, nice. That is certainly a way to go about it. The risk is still there when working with Parcelable, although my solution depends on GSON (or some other serializer) to implement. In any case either solution certainly works. – Caine

I don't think you need to pass via shared preferences. Actually base types are still working, you could pass the json string via the intent and parse it with Gson when receiving it. Also I noticed no troubles with passing a Bitmap... (which implements Parcelable) – Mediatorial

Yep, as ilansas mentioned, it is enough to send it as a String. – Grisly

Fortunately, I am always in a good practice of making JSON out of my POJOs – Adventurism

Answer 2

I have seen this sort of behavior reported before, with custom Parcelable objects and system services (e.g., NotificationManager). What seems to happen is that the system tries using the PendingIntent, and as part of that for some reason it tries to un-Parcel the Parcelable. This fails, because the system doesn't have your classes. I haven't heard of somebody running into this in a while, but it's entirely possible that there is a regression in Android N that re-introduced it.

You might rummage through LogCat to see if there are any messages — or, better yet, stack traces — from the system (not your app) that seem to pertain to your alarm event.

If you can create a reproducible test case, file an issue on the Android issue tracker. If you think of it, post a link to it here, as I'd like to take a peek at it.

In terms of workarounds, I can think of two:

1. Don't put the Parcelable in there. Instead, put an ID that you can use to look up the information as needed, whether from an in-memory cache (if your process happens to still be around) or from whatever your persistent data store is.

2. Switch from Parcelable to what I and others have termed "bundle-able", where you convert your object to and from a Bundle. Basically, stick solely to OS-defined classes, with no custom classes. Then, the system can safely de-Parcel the Bundle (for whatever reason it does so). This, of course, is much more painful than simply using an annotation processor to create the Parcelable implementation.

Hypno

You're definitely correct, I will certainly post an issue up on the tracker. It has to be something with the N sources (which we cannot see yet since it is not officially released) – Caine

@Aceofspadez44: NDP5 sources are not available yet, but NDP4 is. – Hypno

nice! I did compile this project against NDP4 as well and got the same results. Thanks again for the help. I'll have to bundle it OR stick the object in shared prefs with a key and handle it later. – Caine

code.google.com/p/android/issues/… – Caine

@Aceofspadez44: Without a reproducible test case, I do not hold a lot of hope for your issue. – Hypno

good point, I'll set something up using the AlarmManager sample from the googlesamples repo and fix the issue with something to reproduce. – Caine

github.com/CCorrado/android-RepeatingAlarm if you're interested in reproducing this issue yourself, I spun something up quickly that reproduces the issue. – Caine

@Aceofspadez44: I see that you asked about this on the Reddit AMA, and Dianne echoed the concern in my answer. I'm a bit surprised that there's a change in behavior, though -- I would have expected it to either always have been failing or to still work. I'll take a peek at your sample sometime soonish. Thanks! – Hypno

Right! I did indeed. I agree with you, why would this suddenly be a problem on N but not other OSes. Sounds good, let me know if you find a solution using Parcelable, I'll probably just cache the object in/out using SharedPreferences as a fix for this project. – Caine

@Aceofspadez44: Turns out this was reported as an issue nearly two months ago. The Google engineers had the same reaction that Dianne did, and were as surprised as I was that this is a change in behavior. However, they deem this as working as intended. – Hypno

I got the notification today, took a look....looks like I can serialize a String into SharedPrefs with the parcelable, then parse the string out and create a Parcelable from that String. Might need some trickery with GSON but I think i can get it to work.. – Caine

Answer 3

I've found that wrapping the Parcelable in a Bundle works.

// When setting up the PendingIntent for the AlarmManager:
Intent intent = new Intent(context, MyService.class);
MyParcelable myParcelable = new MyParcelable();
Bundle b = new Bundle();
b.putParcelable(EXTRA_MY_PARCELABLE, myParcelable);
intent.putExtra(EXTRA_BUNDLE, b);
PendingIntent.getService(0, intent, 0);

// From the Service (or Activity, BroadcastReceiver, etc.):
Bundle b = intent.getExtra(EXTRA_BUNDLE);
MyParcelable myParcelable = b.getParcelableExtra(EXTRA_MY_PARCELABLE);

However, I'm not sure how future-proof this approach is. I've commented on the issue on the android bug tracker: https://code.google.com/p/android/issues/detail?id=209422#c11 but I doubt it's going to receive a response since the issue has already been marked closed.

Ellingston