Android RxJava2 应用程序在从创建的 observable 中调用emitter.onError() 时崩溃

问题描述

我正在create() 的帮助下手动创建Observable.现在在里面，我检查一些条件 &基于此，我想通知订阅者有关错误.这是我创建可观察对象的方式:

I am creating Observable manually with the help of create(). now inside, I check some conditions & based on that, I would like to notify the subscriber about error. Here's how I am creating observable:

public Observable<User> loginUser(String email, String password) {
    return Observable.create(
        emitter -> {
            myAsynchronousWork.onCompleteListener(
               result -> {
                   if(!result.isSuccess()) {
                      // This causes the crash.
                      emitter.onError(new Throwable(result.getError()));
                   } else {
                      // Process result & create User object & return it. This works as expected.
                      emitter.onNext(user);
                      emitter.onComplete();
                   }
               }
            );

        }
    );

}

&然后我订阅 loginUser() 就像:

& then I subscribe to loginUser() like:

loginUser("", "")
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(user -> {
                    Log.d("TAG", "logged in user => " + user.getUuid());
                    Log.d("TAG", "user name => " + user.getUserName());
                    Log.d("TAG", "user email => " + user.getEmailId());
                }, throwable -> {
                    Log.e("TAG", "error in login => " + throwable.getMessage());
                }, () -> {

                });

我希望调用 emitter.onError() 应该在 loginUser() 的 subscribe() 的 onError 里面，我已经记录了异常，但应用程序因 emitter.onError() 在 logcat 中返回的异常而崩溃，就像没有人来处理它一样！

I expect that calling emitter.onError() should go inside onError of subscribe() of loginUser() where I have Logged the exception, but instead the app gets crashes with the Exception returned by emitter.onError() in logcat like there's no one to handle it!

我通过调试检查过 &发现当它在线 emitter.onError() 时，emitter 是 "null".然而 onNext &onComplete 不会造成任何问题.请让我知道我哪里做错了?

I checked by debugging & found that while it's on line emitter.onError(), emitter was "null". however onNext & onComplete doesn't cause any problem.Please let me know where I am doing wrong?

推荐答案

我的应用程序崩溃的原因是，我实际上有这样的事情:

The reason why my app was getting crashed was, I had actually something like this:

myAsynchronousWork.onCompleteListener(
               result -> {
                   if(!result.isSuccess()) {
                      // This causes the crash.
                      emitter.onError(new Throwable(result.getError()));
                   } else {
                      // Process result & create User object & return it. This works as expected.
                      emitter.onNext(user);
                      emitter.onComplete();
                   }
               },
               exception -> {
                   emitter.onError(exception); // This was the reason of problem!
               }
            );

我没有发布完整的部分，因为我没有意识到它导致了异常.

I didn't posted the full part because I didn't get that it was causing the exception.

这里发生的事情是，我的代码首先进入了 exception-> 部分，它通知观察者关于错误 &那个观察员被终止了.现在我的 result-> 部分正在执行 &在这里，当我再次尝试调用 emitter.onError() 时，它崩溃了，因为没有 emitter 来处理这个 &RxJava2 正在全局抛出它.

What happening here was, my code first was going inside the exception-> part which was notifying the observer about the error & that observer was getting terminated. now my result-> part was getting executed & here when I tried to call again emitter.onError(), it was crashing as there was no emitter to handle this & RxJava2 was throwing it globally.

所以对我来说，我删除了 exception -> 部分，因为它可以在 result -> 上检查结果 &我还用

So for me, I removed the exception -> part as it was any how going to be on result -> where I could check the result & I have also wrapped the emitter.onError with

if(!emitter.isDisposed()) emitter.onError();

因为在我的情况下，如果处理了发射器，可以忽略错误.

because in my case, it was fine to ignore the error if emitter was disposed.

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