没有得到 BehaviorSubject

Question

我已经完成了 android 很多，但对 java 8 还是陌生的。我制作了一个 BehaviourSubject< Map< String,String>>.

我在上面放了一个 observable。来自演示者 class 我将 BehaviourSbuject 设置为可观察的，一旦 onClick 被调用，onNext 就会调用它。但它正在抛出 rx.exceptions.OnErrorNotImplementedException.

我不明白为什么它会抛出这个错误，因为我已经提到了这个 http://reactivex.io/RxJava/javadoc/index.html?rx/exceptions/OnErrorNotImplementedException.html 但是根据这个我只是在 onNext 调用 observable 时仍然得到这个错误。

MainScreenView是MainScreenFragment实现的接口。

主持人class

public class MainScreenPresenter {
public MainScreenPresenter(MainScreenView view, MainScreenModel model) {
    Log.i("MainScreenPresenter", "default constructor");
    view.addPlace().subscribe(place -> model.place(place));
    }
}

MainScreenFragmentclass

public class MainScreenFragment extends Fragment implements MainScreenView, View.OnClickListener {

ArrayList<Place> places;
View mainScreenRootFragment;
Button addPlace;
TextView venueDate;
Place newPlace;
BehaviorSubject<Map<String, String>> placeAdded = BehaviorSubject.create();


@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    mainScreenRootFragment = inflater.inflate(R.layout.main_screen_fragment, container);
    Log.i("MainScreenFragment", "onCreateView");
    setRetainInstance(true);
    return mainScreenRootFragment;
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    Log.i("MainScreenFragment", "onViewCreated");
    initializeViews(view);
    setEventsForViews();
}

private void setEventsForViews() {
    addPlace.setOnClickListener(this);
}

private void initializeViews(View view) {
    addPlace = (Button) view.findViewById(R.id.add_place);
    venueDate = (TextView) view.findViewById(R.id.venue_date);
    places = new ArrayList<>();
}

@Override
public Observable<Map<String, String>> addPlace() {
    Log.i("MainScreenFragment", "addPlace");
    return placeAdded.asObservable();
}

@Override
public void onClick(View v) {
    if (v.getId() == R.id.add_place) {
        Log.i("MainScreenFragment", "add_place button clicked");
        placeData();
        Log.i("MainScreenFragment", "after onNext()");
    } else if (v.getId() == R.id.rv) {

    }
}

private void placeData() {
    Log.i("MainScreenFragment", "data is mapping in placeData()");
    Map<String, String> map = new HashMap<>();

    map.put("placeName", "Lonavala");
    map.put("placeDate", "20/5/2015");
    placeAdded.onNext(map);
    }
}

错误

07-10 10:14:25.414    2754-2754/com.example.vikky.hisab W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41703d58)
07-10 10:14:25.424    2754-2754/com.example.vikky.hisab E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.vikky.hisab, PID: 2754
rx.exceptions.OnErrorNotImplementedException
        at rx.Observable.onError(Observable.java:7204)
        at rx.observers.SafeSubscriber._onError(SafeSubscriber.java:127)
        at rx.observers.SafeSubscriber.onError(SafeSubscriber.java:96)
        at rx.observers.SafeSubscriber.onNext(SafeSubscriber.java:111)
        at rx.internal.operators.NotificationLite.accept(NotificationLite.java:150)
        at rx.subjects.SubjectSubscriptionManager$SubjectObserver.emitNext(SubjectSubscriptionManager.java:254)
        at rx.subjects.BehaviorSubject.onNext(BehaviorSubject.java:166)
        at com.example.vikky.hisab.MainScreenFragment.placeData(MainScreenFragment.java:115)
        at com.example.vikky.hisab.MainScreenFragment.onClick(MainScreenFragment.java:100)
        at android.view.View.performClick(View.java:4444)
        at android.view.View$PerformClick.run(View.java:18440)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5050)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:806)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.example.vikky.hisab.MainScreenPresenter.lambda$new(MainScreenPresenter.java:11)
        at com.example.vikky.hisab.MainScreenPresenter.access$lambda[=12=](MainScreenPresenter.java)
        at com.example.vikky.hisab.MainScreenPresenter$$Lambda.call(Unknown Source)
        at rx.Observable.onNext(Observable.java:7209)
        at rx.observers.SafeSubscriber.onNext(SafeSubscriber.java:104)

提前致谢

Answer 1

在我看来，在您的 OnNext 处理程序中，您正在抛出一个 NullPointerException。我的猜测是 RxJava 然后试图捕获这个并将异常发布到您没有提供的 OnError 处理程序。然后升级为 OnErrorNotImplementedException.

这里有两件事要做：

总是有一个 OnError 处理程序的好习惯。如果你不这样做，就没有办法在异步世界中捕获异常。
我猜 model 是空的，所以调用 model.place(place) 是抛出 NPE 的东西。也许这是你的地方方法，但堆栈跟踪似乎指向 model 为空。

没有得到 BehaviorSubject

Not getting BehaviourSubject

java

android

system.reactive

observable

retrolambda