HashMaps versus reactive programming

Question

I am starting to take reactive programming a little more, and I'm trying to apply it to typical business tasks. One template that I often develop is database-based classes. I have a specific specific class of units, for example ActionProfile, whose instances are controlled by using ActionProfileManagerwhich creates instances from the database table and stores them in Map<Integer,ActionProfile>, where Integeris the key actionProfileId. ActionProfileManagercan periodically clean and re-import data and notify all dependencies in order to re-extract it from its card.

public final class ActionProfileManager {
    private volatile ImmutableMap<Integer,ActionProfile> actionProfiles;

    private ActionProfileManager() { 
        this.actionProfiles = importFromDb();
    }

    public void refresh() { 
        this.actionProfiles = importFromDb();
        notifyEventBus();
    }

    //called by clients on their construction or when notifyEventBus is called
    public ActionProfile forKey(int actionProfileId) { 
        return actionProfiles.get(actionProfiles);
    }

    private ImmutableMap<Integer,ActionProfile> importFromDb() { 
        return ImmutableMap.of(); //import data here
    }
    private void notifyEventBus() { 
        //notify event through EventBus here
    }
}

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public final class ActionProfileManager {
    private final BehaviorSubject<ImmutableMap<Integer,ActionProfile>> actionProfiles;

    private ActionProfileManager() { 
        this.actionProfiles = BehaviorSubject.create(importFromDb());
    }

    public void refresh() { 
        actionProfiles.onNext(importFromDb());
    }

    public Observable<ActionProfile> forKey(int actionProfileId) { 
        return actionProfiles.map(m -> m.get(actionProfileId));
    } 
    private ImmutableMap<Integer,ActionProfile> importFromDb() { 
        return ImmutableMap.of(); //import data here
    }
}

, , Observable<ActionProfile> .

public final class ActionProfileManager {
    private final ReplaySubject<ActionProfile> actionProfiles;

    private ActionProfileManager() { 
        this.actionProfiles = ReplaySubject.create();
        importFromDb();
    }

    public void refresh() { 
        importFromDb();
    }

    public Observable<ActionProfile> forKey(int actionProfileId) { 
        return actionProfiles.filter(m -> m.getActionProfileID() == actionProfileId).last();
    } 
    private void importFromDb() { 
        // call onNext() on actionProfiles and pass each new ActionProfile coming from database
    }
}

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Answer 1

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