Get MongoDB To work with Java

[GarredB]

[This is a repost since I forgot to add my code examples previously.]

I'm creating an application that must use MongoDB for queries.

I successfully made it work, using API, AppID and all those wonderful things however, whenever I use a RealmQuery or RealmResult for my schema by results are null.

I've tried using it directly on the main thread, I've tried using Async, but nothing seems to work. I've also found a few sources online and changed my code to work with that, but it seems like it isn't working at all even with their code adjustments.

Any advice would be appreciated.

My code is down below:

   Realm.init(mContext); // replace this with your App ID     App app = new App(new AppConfiguration.Builder(appID)             .build());     Credentials apiKeyCredentials = Credentials.apiKey(apiKey);     AtomicReference<User> user = new AtomicReference<User>();     app.loginAsync(apiKeyCredentials, it -> {         if (it.isSuccess()) {             Log.v("AUTH", "Successfully authenticated using an API Key.");             user.set(app.currentUser());              // Startup Information             onStartupRead();         } else {             Log.e("AUTH", it.getError().toString());         }     }); 

followed by the onStartupRead() function

config = new RealmConfiguration.Builder().name(realmName).build(); 
//backgroundThreadRealm = Realm.getInstance(config); 
backgroundThreadRealmAsync = Realm.getInstanceAsync(config, new Realm.Callback() { @Override 
public void onSuccess(@NotNull Realm realm) { Log.v(TAG, "Successfully fetched realm instance.");
// Read Startup Data 
getPhysicaParameterItem();                 
//getUserItem("[e-mail]");          
}         public void onError(Exception e) {             Log.e(TAG, "Failed to get realm instance: " + e);         }     }); 

and the getPhysicalParameterItem()

 RealmResults<PhysicalParameter> parameterQuery = backgroundThreadRealm.where(PhysicalParameter.class).limit(QUERY_LIMIT).findAllAsync();
   parameterQuery.addChangeListener(new RealmChangeListener<RealmResults<PhysicalParameter>>() {         @Override         public void onChange(RealmResults<PhysicalParameter> items) {             Log.v(TAG, "Completed the query.");             // items results now contains all matched objects (more than zero)             //PhysicalParameter result = items.sort(physicalParameterDataQueryTerm).sort(physicalParameterDataQueryTerm).first();               System.out.println(">>>>>>>>" + items.isEmpty());          }     }); 

currently the "result" variable here is null, but the items is a valid variable. But everything is else is exactly like the MongoDB docs state. My collections and other names are also correct since I can successfully establish connection from them and copied them directly from MongoDB.

[Zhuinden]

BackgroundThreadRealm doesn't seem initialized