How to find if a restartable is started already?

[sreejithraman]

Is there a method that I can call to see if a certain restartable is started? I have a restartable that is paging, and normally I would just start it in the onCreate() of the presenter but since I need arguments passed to the activity, I have to call a method in the onCreate() of the activity. Now when I rotate the device, the activity is recreated and goes through the whole onCreate() and restarts the restartable. So, I put a boolean check to see if restartable has already started like so:

public void fetchItems(String parentItemId){
        if(!hasStartedPaging) {
            rxPager = new RxPager();
            registerFetchItemsFromServerRestartable(parentItemId); // I just register a restartableReplay 
            start(RESTARTABLE_ID);
            hasStartedPaging = true;
        }
}

Is that how you would recommend doing this or can I replace the hasStartedPaging variable with something that lets me check if a restartable is already started? Or am I completely doing this wrong?

[inorichi]

You can start it when the bundle is null in your activity:

if (savedInstanceState == null) {
    getPresenter().fetchItems(id);
}

If you still want to know if a restartable is running, you will have to copy this class to your project https://github.com/konmik/nucleus/blob/master/nucleus/src/main/java/nucleus/presenter/RxPresenter.java and add a method like this:

public boolean isSubscribed(int restartableId) {
    Subscription s = restartableSubscriptions.get(restartableId);
    return s != null && !s.isUnsubscribed();
}

Edit: Also, don't register the restartable (registerFetchItemsFromServerRestartable(parentItemId);) there. You should register them only in the onCreate method of the presenter. They will do nothing until you call start(x).

[konmik]

It looks like a good idea to include isSubscribed into the next version. Thanks, @inorichi !

[sreejithraman]

@inorichi Correct me if I am wrong, but I can't do

if (savedInstanceState == null) {
    getPresenter().fetchItems(id);
}

because after a crash the savedInstanceState will not be null and the presenter also would be recreated, right?

[inorichi]

After a process restart, the restartable will restart itself (as it's name says), that's why you should store that parentItemId in the presenter's bundle so that you don't get a NPE when accessing it.

The wiki recommends you to use Icepick for saving/restoring instances.

Then you declare a variable with saved state in your presenter like so: @State String parentItemId. In your fetchItems method you add this.parentItemId = parentItemId and everything will work fine.

This answer can help you understanding how restartables work too.