java - RxJava : how to use Observable instead nested loops?

Question

现在我使用带有 ReplaySubject 的嵌套循环获得多个可观察对象，这需要在不使用任何循环的情况下进行转换，只需要可观察对象。

private Observable<BaseUnit> getUnitObservables(ArrayList<Map<Integer, Integer>> list, ReplaySubject<BaseUnit> subject) {

    ArrayList<Observable<BaseUnit>> observables = new ArrayList<>();
    
    for (Map<Integer, Integer> elem : list) {
        for (MapOperationName operationName : MapOperationName.values()) { // MapOperationName type is enum

            Observable<BaseUnit> observable = Observable.fromCallable(() -> {
                // some operations here

                subject.onNext(unit);
                observables.add(observable);
            });
        }
    }
    return Observable.merge(observables);
}

“ Map<Integer, Integer> elem : list”有 3 个元素。
“ MapOperationName.values()”返回 7 个元素。
所以我在上面的例子中完全应该是 21 岁。
试图重构这样的东西，但只得到 3 个元素:

private Observable<BaseUnit> getUnitObservables(ArrayList<Map<Integer, Integer>> list, ReplaySubject<BaseUnit> subject) {

    Observable<ListOperationName> observableOperation = 
    Observable.fromArray(MapOperationName.values());
    Observable<List<Integer>> observableList = Observable.fromIterable(list);
    return Observable.zip(observableList, observableOperation, (listElem, operationElem) -> {

        subject.onNext(unit);
        //some operations here
    });

}

如何正确组合这个 ArrayList和 Enum获得全套配对组合？

Answer 1

您可以将需要执行的操作嵌套在 flatMap 中。为达到这个:

private Observable<BaseUnit> getUnitObservables(ArrayList<Map<Integer, Integer>> list, ReplaySubject<BaseUnit> subject) {

    Observable<ListOperationName> observableOperation = 
        Observable.fromArray(MapOperationName.values());
    Observable<List<Integer>> observableList = Observable.fromIterable(list);
    return observableList
        .flatMap(listElem -> observableOperation
            .map(operationElem -> {
                // some operations here
                subject.onNext(unit);
                return unit;  // Assuming unit is a BaseUnit
            })
        );
}