[英]RxJava update data from Observable
我有2個listview。 它包含文本項。 我想將文本項從左側列表拖放到右側列表。 惠特這我沒問題。 另外,我還有一個Observable,它發出KalturaVideo對象。 這是我如何可觀察到的代碼:此函數獲取已經在正確的listview中添加的ID,並且如果對象ID等於targetList中的某個ID,則從結果中排除對象:
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.combineLatest(
targetIdList,
KalturaVideoRetriver.getVideoList(BuildPlaylistStep2Activity.this, kalturaPlaylistId),
(String[] idListOfTarget, KalturaVideo kalturaVideo) -> {
for (String item :idListOfTarget){
if(item.equals(kalturaVideo.getId())){
return null;
}
}
return kalturaVideo;
})
.doOnError(throwable -> {
int i =0;
i++;
throwable.printStackTrace();
})
.filter(kalturaVideo -> {
return kalturaVideo != null;
});
}
這是視頻檢索的代碼:
public class KalturaVideoRetriver {
public static final String KALTURA_NEW_PLAYLIST_ID = "NEW_PLAYLIST";
public static Observable<KalturaVideo> getVideoList(Context context, String kalturaPlaylistId){
return Observable.create(new Observable.OnSubscribe<KalturaVideo>() {
@Override
public void call(Subscriber<? super KalturaVideo> subscriber) {
getKalturaPlaylistContentObservable(kalturaPlaylistId, context)
.flatMap(new Func1<String[], Observable<?>>() {
@Override
public Observable<?> call(String[] videoIdList) {
return getKalturaVideoListObservable(context, videoIdList)
.doOnNext(kalturaVideo -> {
subscriber.onNext(kalturaVideo);
})
.doOnCompleted(() -> subscriber.onCompleted());
}
})
.subscribe();
}
});
}
private static Observable<KalturaVideo> getKalturaVideoListObservable(Context context, String[] kalturaVideoIdArray){
return Observable.create(new Observable.OnSubscribe<KalturaVideo>() {
@Override
public void call(Subscriber<? super KalturaVideo> subscriber) {
Cursor query;
List<KalturaVideo> result = new ArrayList<>();
if(kalturaVideoIdArray == null || kalturaVideoIdArray.length == 0) {
query = context.getContentResolver().query(KalturaVideoColumns.CONTENT_URI, null, null, null, null);
}else {
KalturaVideoSelection where = new KalturaVideoSelection();
where.kalturaIdLike(kalturaVideoIdArray);
query = context.getContentResolver().query(
KalturaVideoColumns.CONTENT_URI,
null,
where.sel(),
where.args(),
null);
}
if(!query.moveToFirst()){
query.close();
subscriber.onCompleted();
}
KalturaVideoCursor cursor = new KalturaVideoCursor(query);
do{
KalturaVideo video = new KalturaVideo();
video.setId(cursor.getKalturaId());
video.setName(cursor.getName());
video.setDescription(cursor.getDescription());
video.setCategories(cursor.getCategories());
video.setCategoriesIds(cursor.getCategoriesIds());
video.setDownloadUrl(cursor.getDownloadUrl());
video.setThumbnailUrl(cursor.getThumbnailUrl());
video.setDataUrl(cursor.getDataUrl());
video.setDuration(cursor.getDuration());
subscriber.onNext(video);
}while (cursor.moveToNext());
query.close();
subscriber.onCompleted();
}
});
}
private static Observable<String[]> getKalturaPlaylistContentObservable(String kalturaPlaylistId, Context context){
return Observable.create(new Observable.OnSubscribe<String[]>() {
@Override
public void call(Subscriber<? super String[]> subscriber) {
if(kalturaPlaylistId.equals(KALTURA_NEW_PLAYLIST_ID)){
subscriber.onNext(new String[]{});
subscriber.onCompleted();
return;
}
KalturaPlaylistContentSelection where = new KalturaPlaylistContentSelection();
where.playlistId(kalturaPlaylistId);
Cursor query = context.getContentResolver().query(
KalturaPlaylistContentColumns.CONTENT_URI,
null,
where.sel(),
where.args(),
null
);
if(!query.moveToFirst()){
subscriber.onNext(new String[]{});
query.close();
subscriber.onCompleted();
return;
}
KalturaPlaylistContentCursor cursor = new KalturaPlaylistContentCursor(query);
String[] result = new String[query.getCount()];
int index = 0;
do{
result[index] = cursor.getKalturaVideoId();
index++;
}while (query.moveToNext());
query.close();
subscriber.onNext(result);
subscriber.onCompleted();
}
});
}
}
首先,在檢索中,我通過播放列表ID來獲取視頻ID。 如果PlaylistId為空-我將獲取所有視頻ID,並將其存儲在數據庫中。 在此之后,我通過ID獲得了來自db的所有視頻,這是在上一步獲得的。
這是功能,可幫助我獲取所有視頻並顯示它:
private Observable<KalturaVideo> fillLists(){
return getSourceListObservalbe(KalturaVideoRetriver.KALTURA_NEW_PLAYLIST_ID)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnError(throwable -> {
Log.e("TAG", throwable.getCause().toString());
})
.doOnNext(kalturaVideo -> {
sourceList.add(kalturaVideo);
})
.doOnCompleted(() -> {
viewHolder.sourceListView.setAdapter(new BuildPlaylistContentAdapter(
BuildPlaylistStep2Activity.this,
-1,
sourceList));
viewHolder.sourceListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
KalturaVideo video = (KalturaVideo) view.getTag();
ClipData data = ClipData.newPlainText("kalturaVideoId", video.getId());
View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
view.startDrag(data, shadowBuilder, view, 0);
view.setVisibility(View.INVISIBLE);
return false;
}
});
viewHolder.targetListView.setAdapter(new BuildPlaylistContentAdapter(
BuildPlaylistStep2Activity.this,
-1,
targetList
));
});
}
這是我的預定方式:
subscription = fillLists().subscribe();
這是拖放后如何嘗試更新2個列表的方法:
targetList.add(video);
sourceList.clear();
fillLists().subscribe();
視頻-與觀看相關的視頻,已刪除到新列表中。
因此,當我第一次將視圖放到另一個列表時,它可以正常工作。 但是當我第二次掉線時,在我的doOnError方法中得到了這個堆棧跟蹤 :
04-20 18:46:02.072 8015-8083 / com.mediamanagment.app W / System.err:java.lang.NullPointerException 04-20 18:46:02.072
8015-8083 / com.mediamanagment.app W / System.err:位於com.mediamanagment.app.activity.BuildPlaylistStep2Activity.lambda $ getSourceListObservalbe $ 3(BuildPlaylistStep2Activity.java:106)04-20 18:46:02.072 8015-8083 / com帶有com.mediamanagment.app.activity.BuildPlaylistStep2Activity.access $ lambda $ 1(BuildPlaylistStep2Activity.java)的.mediamanagment.app W / System.err 04-20 18:46:02.072 8015-8083 / com.mediamanagment.app W / System com.mediamanagment.app.activity.BuildPlaylistStep2Activity $$ Lambda $ 2.call上的.err:(未知來源)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:在rx.functions .Functions $ 3.call(Functions.java:76)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:at rx.operators.OperatorCombineLatest $ Collector.next(OperatorCombineLatest.java: 157)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於rx.operators.OperatorCombineLatest $ SourceSubscriber.onNext(OperatorCombineLatest.java:218)04-20 18:46:02.080 8015-8083 / com.mediamanagm ent.app W / System.err:at com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 1 $ 1.lambda $ call $ 13(KalturaVideoRetriver.java:36)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 1 $ 1.access $ lambda $ 0(KalturaVideoRetriver.java)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err 1 com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 1 $ 1 $$ Lambda $ 1.call(未知來源)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:rx。可觀察$ 12.onNext(Observable.java:3682)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:在rx.operators.OperatorDoOnEach $ 1.onNext(OperatorDoOnEach.java:61)04 -20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 2.call(KalturaVideoRetriver.java:80)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於com.mediamanagment.app.retrivers.KalturaVideoRetrive r $ 2.call(KalturaVideoRetriver.java:47)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04- 20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04-20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable.unsafeSubscribe(Observable.java:6110)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err :at rx.operators.OperatorMerge $ 1.onNext(OperatorMerge.java:66)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:rx.operators.OperatorMerge $ 1.onNext( OperatorMerge.java:43)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:at rx.operators.OperatorMap $ 1.onNext(OperatorMap.java:54)04-20 18: 46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 3.call(KalturaVideoRetriver.java:93)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 3.call(KalturaVideoRetriver.java:89)04-20 18:46:02.080 8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04-20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.080
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04-20 18:46:02.088
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.088
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable.subscribe(Observable.java:6177)04-20 18:46:02.088
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable.subscribe(Observable.java:5842)04-20 18:46:02.088
8015-8083 / com.mediamanagment.app W / System.errag位於com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 1.call(KalturaVideoRetriver.java:41)04-20 18:46:02.088 8015-8083 / com.mediamanag .com W / System.err:com.mediamanagment.app.retrivers.KalturaVideoRetriver $ 1.call(KalturaVideoRetriver.java:27)04-20 18:46:02.088 8015-8083 / com.mediamanagment.app W / System.err :在rx.Observable.unsafeSubscribe(Observable.java:6110)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err:在rx.operators.OperatorCombineLatest.call(OperatorCombineLatest.java: 87)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err:at rx.operators.OperatorCombineLatest.call(OperatorCombineLatest.java:40)04-20 18:46:02.095 8015- 8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04-20 18:46:02.095
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.095
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:153)04-20 18:46:02.095
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable $ 2.call(Observable.java:149)04-20 18:46:02.095
8015-8083 / com.mediamanagment.app W / System.err:位於rx.Observable.unsafeSubscribe(Observable.java:6110)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err :在rx.operators.OperatorSubscribeOn $ 1 $ 1.call(OperatorSubscribeOn.java:60)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err在rx.schedulers.NewThreadScheduler $ NewThreadWorker $ ScheduledAction.run(NewThreadScheduler.java:141)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err:at java.util.concurrent.Executors $ RunnableAdapter.call(Executors.java: 390)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app W / System.err:at java.util.concurrent.FutureTask.run(FutureTask.java:234)04-20 18:46:02.095 8015-8083 / com.mediamanagment.app,位於java.util.concurrent.ScheduledThreadPoolExecutor $ ScheduledFutureTask.access $ 201(ScheduledThreadPoolExecutor.java:153)的W / System.err:04-20 18:46:02.103 8015-8083 / com.mediamanagment .app W / System.err:位於java.util.concurrent.ScheduledThreadPoolExecutor $ Sched uledFutureTask.run(ScheduledThreadPoolExecutor.java:267)04-20 18:46:02.103 8015-8083 / com.mediamanagment.app W / System.err:at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 04-20 18:46:02.103 8015-8083 / com.mediamanagment.app W / System.err:at java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:573)04-20 18:46:02.103 8015-8083 / com.mediamanagment.app W / System.err:位於java.lang.Thread.run(Thread.java:856)
沒有任何視頻返回
您在此代碼中有一個NullPointerException
Log.e("TAG", throwable.getCause().toString());
我認為您的異常沒有原因,因此toString
調用會引發NPE(NullPointerException)
將您的代碼替換為
Log.e("TAG", throwable.getCause());
它應該解決這個問題
但是您的代碼非常復雜,並且某些部分可以用不同的方式編寫。 其他一些越野車。
例如 :
竊聽器
.doOnError(throwable -> {
int i =0;
i++;
throwable.printStackTrace();
})
i
將始終等於0(或i++
之后為1)。 是自願的嗎?
錯誤的代碼
public static Observable<KalturaVideo> getVideoList(Context context, String kalturaPlaylistId){
return Observable.create(new Observable.OnSubscribe<KalturaVideo>() {
@Override
public void call(Subscriber<? super KalturaVideo> subscriber) {
getKalturaPlaylistContentObservable(kalturaPlaylistId, context)
.flatMap(new Func1<String[], Observable<?>>() {
@Override
public Observable<?> call(String[] videoIdList) {
return getKalturaVideoListObservable(context, videoIdList)
.doOnNext(kalturaVideo -> {
subscriber.onNext(kalturaVideo);
})
.doOnCompleted(() -> subscriber.onCompleted());
}
})
.subscribe();
}
});
}
不要在Observable 中使用Observable。 只需轉換第一個
public static Observable<KalturaVideo> getVideoList(Context context, String kalturaPlaylistId){
return getKalturaPlaylistContentObservable(kalturaPlaylistId, context).flatMap((String[] videoIdList) -> getKalturaVideoListObservable(context, videoIdList));
}
復雜代碼
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;
});
您嘗試重寫Rx本身已經可以執行的代碼。
Observable<String[]> targetIdList = Observable.just(targetList)
.flatMapIterable(videos -> videos)
.map(video -> video.getId())
.toList()
.map(l -> l.toArray(new String[]));
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