将List<Observable<String>>合并到Observable<List<String>>中

import io.reactivex.Observable;
import io.reactivex.functions.Function;

public class Main {
    public static void main(String[] args) {
        List<Observable<String>> observables = new ArrayList<>();
        observables.add(Observable.just("Hello"));
        observables.add(Observable.just("World"));

        Observable<List<String>> mergedObservable = Observable.fromIterable(observables)
                .flatMap(new Function<Observable<String>, Observable<String>>() {
                    @Override
                    public Observable<String> apply(Observable<String> observable) throws Exception {
                        return observable;
                    }
                })
                .toList()
                .toObservable();

        mergedObservable.subscribe(strings -> {
            for (String s : strings) {
                System.out.println(s);
            }
        });
    }
}