RealmList sort async?

Question

I just wondered if there is a way to sort a RealmList asynchronously on Android.

Say I have a realm object called diaryEntry which contains a RealmList of Entry objects:

RealmList<Entry> entries;
public RealmList<Entry> getEntries() { return entries; }

If i want to sort the RealmList I simply call sort and thats it, it works fine.

RealmResults<Entry> sortedEntries = diaryEntry.getEntries().sort("time");
mvpView.bindAndShowEntryList(sortedEntries);

The above code however is executed in a Fragment´s onResumeFragment() method which gets called when the Fragment becomes visible (it´s a custom lifecycle method I introduced) in a ViewPager. So obviously it would be nice if I could sort the data in the background and when the fragment becomes visible simply bind the results to the view.

So I came up with a second solution below:

entries = realm.where(Entry.class)
                .equalTo("dateId", dateId)
                .findAllSortedAsync("time");

Note: dateId is an integer and is a unique ID for every Fragment in the ViewPager. This way I had to add a new indexed integer field dateId to the Entry.class.

public class Entry extends RealmObject {
    // Other fields ...
    @Index
    private int dateId;

My question: Is there a way to sort a RealmList asynchronously? If not, which approach may be better? The first one which sorts the entries on the UI thread but has instant access to a RealmList containing all the corresponding Entry objects (in average 10-15 Entry objects). Or the second approach, which has to find all corresponding Entry objects first by their dateId, but does all of that async without blocking the UI thread?

Note: In average there are about 10-15 Entry objects for every unique dateId, so if a normal user is using my app for 2 years and adds about 15 entries every day there will be about 11000 Entry objects in the database. This is obviously a pretty high assumption as no user will add entries every day and not even that much.

Answer 1

You can do:

RealmResults<Entry> sortedEntries = diaryEntry.getEntries()
            .where()
            .findAllSortedAsync("time");

This will create a query based on your entries list and the query will be executed in the background thread.