如何在RxJava中压缩2个不同长度的observable

Question

我有两个可观察量:

Observable<String[]>

和

Observable<KalturaVideo>

我想检查每个KalturaVideo.getId(),它是否包含在String []中,它返回第一个observable,如果它包含,则不要在sourceList中发出它.

所以,第一个可观察到的emmits String []只有一次,但是第二个可观察的emmits项目是17次.如何恰当地组合这两个可观测量？这是我的解决方案:

private Observable<KalturaVideo> getSourceListObservalbe(String kalturaPlaylistId){
        Observable<String[]> targetIdList = Observable.just(targetList)
                .map((List<KalturaVideo> kalturaVideos) -> {
                    if(kalturaVideos == null || kalturaVideos.isEmpty()){
                        return new String[]{""};
                    }
                    String[] result = new String[kalturaVideos.size()];
                    int index = 0;
                    for (KalturaVideo item : kalturaVideos) {
                        result[index] = item.getId();
                    }
                    return result;
                });
        return Observable.zip(
                targetIdList,
                KalturaVideoRetriver.getVideoList(BuildPlaylistStep2Activity.this, kalturaPlaylistId),
                (String[] idListOfTarget, KalturaVideo kalturaVideo) -> {
                    for (String item :idListOfTarget){
                        if(item.equals(kalturaVideo.getId())){
                            return null;
                        }
                    }
                    return kalturaVideo;
                })
                .filter(kalturaVideo -> {
                    return kalturaVideo != null;
                });
    }

targetList - 我想从sourceList中排除的KalturaVideo列表,KalturaVideoRetriver.getVideoList - 返回sourceList

这个解决方案只给我一个KalturaVideo,但我需要17个

Answer 1

你可以使用combineLatest而不是zip:

return Observable.combineLatest(
    targetIdList,
    KalturaVideoRetriver.getVideoList(BuildPlaylistStep2Activity.this, kalturaPlaylistId),
    (String[] idListOfTarget, KalturaVideo kalturaVideo) -> {
        ...
        return kalturaVideo;
    })

combineLatest有点像zip,但它结合了每个最近的排放.

所以在你的情况下,你的targetIdListobservable发出一个单一的String[].combineLatest将用你的其他可观察物的每一次发射拉上那个.