Question

如下面的代码所示，由于强制转换不正确，我在以下一行中收到一条错误消息

I am using the folloing rx versions
compile 'io.reactivex.rxjava2:rxandroid:2.0.2'
compile 'io.reactivex.rxjava2:rxjava:2.0.5'

请让我知道如何解决此问题。

注释：

import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;
import io.reactivex.Observer;
import io.reactivex.Scheduler;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.Disposable;
import io.reactivex.functions.Consumer;
import io.reactivex.schedulers.Schedulers;

代码：

getAnimalsObservable()
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe((Consumer<? super List<String>>)getAnimalsObserver());



 private Observer<String> getAnimalsObserver() {
    return new Observer<String>() {

        @Override
        public void onSubscribe(Disposable d) {
            Log.i(TAG, "onSubscribe->d: " + d);
        }

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

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

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

公共类MainActivity扩展了AppCompatActivity {

Caused by: java.lang.ClassCastException: 
com.example.pc_a.myapplication.MainActivity$1 cannot be cast to 
io.reactivex.functions.Consumer
at com.example.pc_a.myapplication.MainActivity.onCreate(MainActivity.java:38)
at android.app.Activity.performCreate(Activity.java:6288)
at 
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
t android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2642)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2754)

logcat ：

SELECT
  date,
  COUNT(DISTINCT(fullVisitorId)) as daily_active_user,
  SUM(count(Distinct(fullVisitorId))) OVER (ORDER BY date ROWS BETWEEN 29 PRECEDING AND CURRENT ROW) AS monthly_active_user
FROM
  `bigquery-public-data.google_analytics_sample.ga_sessions_2017*`,
  unnest(hits) as h
WHERE
  _table_suffix BETWEEN "0101" AND "0715"
GROUP BY
  date

Answer 1

首先，您无需强制转换为Consumer。其次，您应该按如下方式修改Observer使其起作用（Observer已经可以在subscribe中使用）。我对其进行了简化以使其更加整洁：

private Observable<List<String>> getAnimalsObservable() {
    return Observable.fromArray(Arrays.asList(
        new String[]{
            "Ant", "Ape",
            "Bat", "Bee", "Bear", "Butterfly",
            "Cat", "Crab", "Cod",
            "Dog", "Dove",
            "Fox", "Frog"
        }
    ));
}

private Observer<List<String>> getObserver() {
    return new Observer<List<String>>() {
        @Override
        public void onSubscribe(Disposable d) {
            //your logic here
        }

        @Override
        public void onNext(List<String> values) {
            //your logic here
            for (String value : values) {
                System.out.print(value + " ");
            }
        }

        @Override
        public void onError(Throwable e) {
            //your logic here
        }

        @Override
        public void onComplete() {
            //your logic here
        }
    };
}

@Test
public void test() {
    // here you can add your observeOn and subscribeOn but they're not important for the test
    getAnimalsObservable()
        .subscribe(getObserver());
}

输出：

蚂蚁猿蝙蝠蜜蜂熊蝴蝶猫蟹鳕鱼狗鸽子狐狸青蛙

错误转换为observable.subscribe

1 个答案: