[英]Convert/ wrap async listener to Observable (RxJava2)
我想将一个真正的侦听器包装到Observable对象中。 对于初学者来说,这是一个测试案例,一切都很好。
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
getObservablePhoneState()
// Run on a background thread
.subscribeOn(Schedulers.io())
// Be notified on the main thread
.observeOn(AndroidSchedulers.mainThread())
.subscribe(integer -> Log.i(TAG, "----- subscribe onNext = " + integer));
}
private Flowable<Integer> getObservablePhoneState() {
return Flowable.create(emitter -> {
Log.i(TAG, "Emitting 1");
emitter.onNext(1);
Log.i(TAG, "Emitting 2");
emitter.onNext(2);
}, BackpressureStrategy.BUFFER);
}
*** logcat ***
Emitting 1
Emitting 2
----- subscribe onNext = 1
----- subscribe onNext = 2
此代码生成错误:
private Flowable<Integer> getObservablePhoneState() {
return Flowable.create(emitter -> {
PhoneStateListener phoneStateListener = new PhoneStateListener() {
@Override
public void onCallStateChanged(int state, String incomingNumber) {
Log.i(TAG, "onCallStateChanged = " + state);
emitter.onNext(state);
}
};
TelephonyManager telephonyManager = (TelephonyManager) getActivity().getSystemService(Context.TELEPHONY_SERVICE);
telephonyManager.listen(phoneStateListener, PhoneStateListener.LISTEN_CALL_STATE);
}, BackpressureStrategy.BUFFER);
}
*** logcat ***
io.reactivex.exceptions.OnErrorNotImplementedException:
Attempt to read from field 'android.os.MessageQueue
android.os.Looper.mQueue' on a null object reference
与Observable.create()相同的错误。 也许这是因为RxJava2不支持发出空值 。
怎么做对了?
您应该删除subscribeOn(Schedulers.io())
以避免在另一个线程中创建PhoneStateListener
,因为在PhoneStateListener
尝试使用mQueue为null的Handler发送消息。 打电话吧
getObservablePhoneState()
.subscribe { integer -> Log.i("", "----- subscribe onNext = " + integer) }
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.