发表新帖
发表新帖

Fallback Observable for RxJava

前端 未结
关注
6 1428
-上瘾入骨i
-上瘾入骨i 2021-02-02 00:25

I\'m in search for a better way to achieve a simple Observable fallback system for empty results when using RxJava. The idea is that, if a local query for a set of data results

6条回答
  • 北海茫月
    北海茫月 (楼主)
    2021-02-02 01:13

    I'm sure there's more elegant solution to this problem but you could simply use flatMap in this case. Since you're already dealing the List which is returned from queryLocalDatabase() method you could do something like this.

    Observable.create(new Observable.OnSubscribe>() {
    @Override
    public void call(Subscriber> subscriber) {
        List results = queryLocalDatabase();
        subscriber.onNext(results);
        subscriber.onCompleted();
    }

    private List queryLocalDatabase() {
        return Arrays.asList();
    }

}).flatMap(new Func1, Observable>() {
    @Override
    public Observable call(List list) {
        if (list.isEmpty()) {
            return getFallbackObservable();
        } else {
            return Observable.from(list);
        }
    }

    private Observable getFallbackObservable() {
        return Observable.from("3", "4");
    }

}).subscribe(new Observer() {
    @Override
    public void onCompleted() {
        System.out.println("onCompleted");
    }

    @Override
    public void onError(Throwable e) {
        System.out.println("onError");
    }

    @Override
    public void onNext(String s) {
        System.out.println("onNext: " + s);
    }
});

    I've replace Object for String for the purpose of this code.

    0 讨论(0)
     看不清?
    提交回复
    热议问题