当我在FlowableOnSubscribe类中调用onNext时，我的订阅者的onNext和onComplete函数不会运行

问题描述

在使用RxJava 2的Android项目中，我在初始化的 onCreate 中创建了一个 Flowable 活动：

In an Android project that uses RxJava 2, I create a Flowable like this in the onCreate of my initial activity:

Flowable.create(new MyFlowableOnSubscribe1(), BackpressureStrategy.BUFFER)
        .doOnComplete(new MyAction())
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new MySubscriber());

FlowableOnSubscribe的实施是：

The implementation of the FlowableOnSubscribe is:

public class MyFlowableOnSubscribe1 implements FlowableOnSubscribe<String> {
    public static final String TAG = "XX MyFlOnSub1";

    @Override
    public void subscribe(FlowableEmitter<String> emitter) {
        Log.i(TAG, "subscribe");

        emitter.onNext("hello");
        emitter.onComplete();
    }
}

这是订户实施：

public class MySubscriber implements Subscriber<String> {
    public static final String TAG = "XX MySubscriber";

    @Override
    public void onSubscribe(Subscription s) {
        Log.i(TAG, "onSubscribe");
    }

    @Override
    public void onComplete() {
        Log.i(TAG, "onComplete");
    }

    @Override
    public void onError(Throwable e) {
        Log.i(TAG, "onError");
    }

    @Override
    public void onNext(String s) {
        Log.i(TAG, "onNext: " + s);
    }
}

行动实施是：

public class MyAction implements Action {
    public static final String TAG = "XX MyAction";

    @Override
    public void run() {
        Log.i(TAG, "run");
    }
}

在我的输出中，我期待一个日志来自 onNext 的声明，但我没有看到。相反，这是我的整个输出：

In my output, I'm expecting to a log statement from onNext, but I don't see one. Instead, this is my entire output:

02-23 17:56:31.334 24176-24176/com.ebelinski.rxjavaexperimentproject I/XX MySubscriber: onSubscribe
02-23 17:56:31.334 24176-24219/com.ebelinski.rxjavaexperimentproject I/XX MyFlOnSub1: subscribe
02-23 17:56:31.334 24176-24219/com.ebelinski.rxjavaexperimentproject I/XX MyAction: run

这表示 onNext 从不运行， onComplete 甚至都没有运行。但是 MyAction 成功运行。

This indicates that onNext never runs, and onComplete doesn't even run either. But MyAction runs successfully.

以下是当我注释掉 onNext的调用时会发生什么：

02-23 17:58:31.572 24176-24176/com.ebelinski.rxjavaexperimentproject I/XX MySubscriber: onSubscribe
02-23 17:58:31.572 24176-26715/com.ebelinski.rxjavaexperimentproject I/XX MyFlOnSub1: subscribe
02-23 17:58:31.572 24176-26715/com.ebelinski.rxjavaexperimentproject I/XX MyAction: run
02-23 17:58:31.652 24176-24176/com.ebelinski.rxjavaexperimentproject I/XX MySubscriber: onComplete

在这种情况下， onNext 当然不会运行，但至少 onComplete 运行。

In this case onNext of course doesn't run, but at least onComplete runs.

我预计在两种情况下都会看到 onComplete ，而 onNext 当我打电话给 emitter.onNext 时运行。我在这里做错了什么？

I expected that I would see onComplete run in both cases, and onNext run when I call emitter.onNext. What am I doing wrong here?

推荐答案

您需要手动发出请求，否则在扩展<$ c时不会发出任何数据$ c> Subscriber 直接：

You need to manually issue a request otherwise no data will be emitted when extending Subscriber directly:

@Override
public void onSubscribe(Subscription s) {
    Log.i(TAG, "onSubscribe");
    s.request(Long.MAX_VALUE);
}

或者，你可以扩展 DisposableSubscriber 或 ResourceSubscriber 。

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