我已经知道不同类型视图的RecyclerView是如何工作的，但这次我试图将本地高级Admob广告添加到我的RecyclerView中。我按照以下步骤进行Youtube教程 但在应用程序崩溃后，有一个错误打印到我的logcat。
日志猫
java.lang.ClassCastException: com.google.android.gms.internal.ads.zzaeh cannot be cast to mgb.com.sdalyricsplus.Database.Entities.SongsEntity
at mgb.com.sdalyricsplus.newAdapters.DisplayItemAdapter.onBindViewHolder(DisplayItemAdapter.java:98)
at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7065)
at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7107)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6012)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6279)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1627)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
我复习了很多次教程，希望我漏掉了一些导致错误的东西，但似乎我按照教程正确地进行了操作。
以下是我的代码
DisplayItemActivity
public class DisplayItemActivity extends AppCompatActivity{
public static final int NUMBER_OF_AD = 5;
AdLoader adLoader;
FastScrollRecyclerView recyclerView;
Global global;
RoomViewModel model;
List<Object> recyclerViewItems = new ArrayList<>();
List<UnifiedNativeAd> nativeAds = new ArrayList<>();
DisplayItemAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_songs);
MobileAds.initialize(this,"ca-app-pub-2493911630710964~1147957926");
recyclerView = findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setHasFixedSize(true);
global = (Global)getApplication();
model = ViewModelProviders.of(this).get(RoomViewModel.class);
adapter = new DisplayItemAdapter(getLayoutInflater());
recyclerView.setAdapter(adapter);
recyclerViewItems.addAll(model.selectAll());
loadNativeAds();
}
private void loadNativeAds() {
AdLoader.Builder builder = new AdLoader.Builder(this, getResources().getString(R.string.native_advance));
adLoader = builder.forUnifiedNativeAd(new UnifiedNativeAd.OnUnifiedNativeAdLoadedListener() {
@Override
public void onUnifiedNativeAdLoaded(UnifiedNativeAd unifiedNativeAd) {
nativeAds.add(unifiedNativeAd);
if (!adLoader.isLoading()) {
insertAdToList();
}
}
}).withAdListener(new AdListener() {
@Override
public void onAdFailedToLoad(int i) {
super.onAdFailedToLoad(i);
if (!adLoader.isLoading()) {
insertAdToList();
}
}
}).build();
adLoader.loadAds(new AdRequest.Builder().build(), NUMBER_OF_AD);
}
private void insertAdToList() {
int offset = recyclerViewItems.size() / (nativeAds.size() + 1);
int index = 0;
for (UnifiedNativeAd ad : nativeAds) {
recyclerViewItems.add(index,ad);
index = index + offset;
}
adapter.setList(recyclerViewItems);
}
}
而我的适配器
DisplayItemAdapter
public class DisplayItemAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final int MENU_ITEM_VIEW_TYPE = 0;
private final int UNIFIED_NATIVE_AD_VIEW_TYPE = 1;
private List<Object> recyclerViewItems = new ArrayList<>();
private Global global;
private String searchTxt = "";
private final String newline = System.getProperty("line.separator");
private ClickSongItemListener clickSongItemListener;
private ChangeFavoriteListener changeFavoriteListener;
private LayoutInflater layoutInflater;
public DisplayItemAdapter(LayoutInflater layoutInflater) {
this.layoutInflater = layoutInflater;
}
public void setList(List<Object> list) {
this.recyclerViewItems = list;
notifyDataSetChanged();
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
global = (Global) ((Activity)parent.getContext()).getApplication();
switch (viewType) {
case UNIFIED_NATIVE_AD_VIEW_TYPE:
View adView = LayoutInflater.from(parent.getContext()).inflate(R.layout.native_ad_view,parent,false);
return new UnifiedNativeAdViewHolder(adView);
case MENU_ITEM_VIEW_TYPE :
default:
View songitem = LayoutInflater.from(parent.getContext()).inflate(R.layout.gospel_song_item,parent,false);
return new SongItemViewHolder(songitem);
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
int viewType = getItemViewType(position);
switch (viewType) {
case UNIFIED_NATIVE_AD_VIEW_TYPE :
UnifiedNativeAdViewHolder nativeAdViewHolder = (UnifiedNativeAdViewHolder)holder;
UnifiedNativeAd unifiedNativeAd = (UnifiedNativeAd) recyclerViewItems.get(position);
// poulateNativeAdView(unifiedNativeAd,((UnifiedNativeAdViewHolder)holder).getAdView());
FrameLayout frameLayout =
nativeAdViewHolder.view.findViewById(R.id.ad_frame_placement);
UnifiedNativeAdView adView = (UnifiedNativeAdView) layoutInflater
.inflate(R.layout.ad_unified, null);
populateUnifiedNativeAdView(unifiedNativeAd, adView);
frameLayout.removeAllViews();
frameLayout.addView(adView);
break;
case MENU_ITEM_VIEW_TYPE :
default:
SongItemViewHolder songItemViewHolder = (SongItemViewHolder)holder;
setSongViews(songItemViewHolder, (SongsEntity)recyclerViewItems.get(position));
}
}
private void populateUnifiedNativeAdView(UnifiedNativeAd nativeAd, UnifiedNativeAdView adView) {
// Set the media view.
adView.setMediaView((MediaView) adView.findViewById(R.id.ad_media));
// Set other ad assets.
adView.setHeadlineView(adView.findViewById(R.id.ad_headline));
adView.setBodyView(adView.findViewById(R.id.ad_body));
adView.setCallToActionView(adView.findViewById(R.id.ad_call_to_action));
adView.setIconView(adView.findViewById(R.id.ad_app_icon));
adView.setPriceView(adView.findViewById(R.id.ad_price));
adView.setStarRatingView(adView.findViewById(R.id.ad_stars));
adView.setStoreView(adView.findViewById(R.id.ad_store));
adView.setAdvertiserView(adView.findViewById(R.id.ad_advertiser));
// The headline and mediaContent are guaranteed to be in every UnifiedNativeAd.
((TextView) adView.getHeadlineView()).setText(nativeAd.getHeadline());
adView.getMediaView().setMediaContent(nativeAd.getMediaContent());
// These assets aren't guaranteed to be in every UnifiedNativeAd, so it's important to
// check before trying to display them.
if (nativeAd.getBody() == null) {
adView.getBodyView().setVisibility(View.INVISIBLE);
} else {
adView.getBodyView().setVisibility(View.VISIBLE);
((TextView) adView.getBodyView()).setText(nativeAd.getBody());
}
if (nativeAd.getCallToAction() == null) {
adView.getCallToActionView().setVisibility(View.INVISIBLE);
} else {
adView.getCallToActionView().setVisibility(View.VISIBLE);
((Button) adView.getCallToActionView()).setText(nativeAd.getCallToAction());
}
if (nativeAd.getIcon() == null) {
adView.getIconView().setVisibility(View.GONE);
} else {
((ImageView) adView.getIconView()).setImageDrawable(
nativeAd.getIcon().getDrawable());
adView.getIconView().setVisibility(View.VISIBLE);
}
if (nativeAd.getPrice() == null) {
adView.getPriceView().setVisibility(View.INVISIBLE);
} else {
adView.getPriceView().setVisibility(View.VISIBLE);
((TextView) adView.getPriceView()).setText(nativeAd.getPrice());
}
if (nativeAd.getStore() == null) {
adView.getStoreView().setVisibility(View.INVISIBLE);
} else {
adView.getStoreView().setVisibility(View.VISIBLE);
((TextView) adView.getStoreView()).setText(nativeAd.getStore());
}
if (nativeAd.getStarRating() == null) {
adView.getStarRatingView().setVisibility(View.INVISIBLE);
} else {
((RatingBar) adView.getStarRatingView())
.setRating(nativeAd.getStarRating().floatValue());
adView.getStarRatingView().setVisibility(View.VISIBLE);
}
if (nativeAd.getAdvertiser() == null) {
adView.getAdvertiserView().setVisibility(View.INVISIBLE);
} else {
((TextView) adView.getAdvertiserView()).setText(nativeAd.getAdvertiser());
adView.getAdvertiserView().setVisibility(View.VISIBLE);
}
// This method tells the Google Mobile Ads SDK that you have finished populating your
// native ad view with this native ad.
adView.setNativeAd(nativeAd);
// Get the video controller for the ad. One will always be provided, even if the ad doesn't
// have a video asset.
VideoController vc = nativeAd.getVideoController();
// Updates the UI to say whether or not this ad has a video asset.
if (vc.hasVideoContent()) {
// videoStatus.setText(String.format(Locale.getDefault(),
// "Video status: Ad contains a %.2f:1 video asset.",
// vc.getAspectRatio()));
// Create a new VideoLifecycleCallbacks object and pass it to the VideoController. The
// VideoController will call methods on this object when events occur in the video
// lifecycle.
vc.setVideoLifecycleCallbacks(new VideoController.VideoLifecycleCallbacks() {
@Override
public void onVideoEnd() {
// Publishers should allow native ads to complete video playback before
// refreshing or replacing them with another ad in the same UI location.
super.onVideoEnd();
}
});
} else {
}
}
private void setSongViews(SongItemViewHolder viewHolder, SongsEntity note) {
Context context = viewHolder.itemView.getContext();
if (note.getMedia_extension().equals("audio")) {
Glide.with(context)
.load(R.drawable.music_icon)
.thumbnail(00.1f)
.into(viewHolder.iv_thumbnail);
}else if (note.getGenre().toLowerCase().contains("karaoke")) {
File file = new File(context.getExternalFilesDir(null)+"/.file"+note.getId());
if (file.exists()) {
Glide.with(context)
.setDefaultRequestOptions(new RequestOptions().placeholder(R.drawable.karaoke_icon))
.load(file)
.thumbnail(00.1f)
.into(viewHolder.iv_thumbnail);
}else {
Glide.with(context)
.setDefaultRequestOptions(new RequestOptions().placeholder(R.drawable.karaoke_icon))
.load(note.getMedia_url())
.thumbnail(00.1f)
.into(viewHolder.iv_thumbnail);
}
}else {
Glide.with(context)
.load(R.drawable.lyrics_icon)
.thumbnail(00.1f)
.into(viewHolder.iv_thumbnail);
}
viewHolder.title.setText(global.capitalize(note.getTitle()));
viewHolder.artist.setText(global.capitalize(note.getArtist()));
viewHolder.category.setText(note.getGenre());
viewHolder.favorite.setOnCheckedChangeListener(null);
viewHolder.favorite.setChecked(note.getFavorites());
viewHolder.views.setText(note.getFavorite_counter() <2 ? note.getFavorite_counter()+" heart" : note.getFavorite_counter()+" hearts");
String MY_ID = "JUntYdabhUh5XtMhfCIXXwNbsdW2";
if (!note.getUploader_id().equals(MY_ID))
Glide.with(context)
.setDefaultRequestOptions(new RequestOptions().placeholder(R.mipmap.sda_logo).diskCacheStrategy(DiskCacheStrategy.ALL))
.load(note.getUploader_photo_url())
.into(viewHolder.user_logo);
else
Glide.with(context)
.load(R.mipmap.sda_logo)
.into(viewHolder.user_logo);
String lyrics = note.getLyrics().toLowerCase();
String searchFilter = searchTxt.toLowerCase();
if (searchTxt.isEmpty()) {
viewHolder.phrase_end.setText(note.getLyrics());
viewHolder.phrase.setText("");
} else
if (lyrics.contains(searchFilter) && (lyrics.indexOf(searchFilter)) + searchTxt.length() <= lyrics.length()) {
viewHolder.phrase.setText(searchTxt);
String filter = note.getLyrics().substring(lyrics.indexOf(searchFilter) + searchFilter.length());
assert newline != null;
viewHolder.phrase_end.setText(filter.replaceAll(newline, " "));
}else {
viewHolder.phrase_end.setText(note.getLyrics());
viewHolder.phrase.setText("");
}
viewHolder.favorite.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (changeFavoriteListener != null) {
changeFavoriteListener.onChange(buttonView.getContext(),note,isChecked);
}
}
});
}
private void poulateNativeAdView(UnifiedNativeAd unifiedNativeAd, UnifiedNativeAdView adView) {
((TextView)adView.getHeadlineView()).setText(unifiedNativeAd.getHeadline());
((TextView)adView.getBodyView()).setText(unifiedNativeAd.getBody());
((TextView)adView.getCallToActionView()).setText(unifiedNativeAd.getCallToAction());
NativeAd.Image icon = unifiedNativeAd.getIcon();
if (icon == null) {
adView.getIconView().setVisibility(View.INVISIBLE);
}else {
((ImageView)adView.getIconView()).setImageDrawable(icon.getDrawable());
adView.getIconView().setVisibility(View.VISIBLE);
}
if (unifiedNativeAd.getPrice() == null) {
adView.getPriceView().setVisibility(View.INVISIBLE);
}else {
adView.getPriceView().setVisibility(View.VISIBLE);
((TextView)adView.getPriceView()).setText(unifiedNativeAd.getPrice());
}
if (unifiedNativeAd.getStore() == null) {
adView.getStoreView().setVisibility(View.INVISIBLE);
}else {
adView.getStoreView().setVisibility(View.VISIBLE);
((TextView)adView.getStoreView()).setText(unifiedNativeAd.getStore());
}
if (unifiedNativeAd.getStarRating() == null) {
adView.getStarRatingView().setVisibility(View.INVISIBLE);
}else {
adView.getStarRatingView().setVisibility(View.VISIBLE);
((RatingBar)adView.getStarRatingView()).setRating(unifiedNativeAd.getStarRating().floatValue());
}
if (unifiedNativeAd.getAdvertiser() == null) {
adView.getAdvertiserView().setVisibility(View.INVISIBLE);
}else {
adView.getAdvertiserView().setVisibility(View.VISIBLE);
((TextView)adView.getAdvertiserView()).setText(unifiedNativeAd.getAdvertiser());
}
adView.setNativeAd(unifiedNativeAd);
}
@Override
public int getItemCount() {
return recyclerViewItems.size();
}
public class SongItemViewHolder extends RecyclerView.ViewHolder {
TextView title, phrase,phrase_end;
TextView artist;
TextView category;
ToggleButton favorite;
LinearLayout layoutWrapper;
LinearLayout phrase_layout;
TextView views;
CircleImageView user_logo;
ImageView iv_thumbnail;
public SongItemViewHolder(@NonNull View itemView) {
super(itemView);
title = itemView.findViewById(R.id.text_view_title);
iv_thumbnail = itemView.findViewById(R.id.iv_thumbnail);
artist = itemView.findViewById(R.id.text_view_artist);
phrase = itemView.findViewById(R.id.phrase);
phrase_end = itemView.findViewById(R.id.phrase_end);
category = itemView.findViewById(R.id.text_view_category);
favorite = itemView.findViewById(R.id.toggleButton_favorite);
layoutWrapper = itemView.findViewById(R.id.layout_wrapper);
phrase_layout = itemView.findViewById(R.id.phrase_layout);
views = itemView.findViewById(R.id.tv_view_status);
user_logo = itemView.findViewById(R.id.user_logo);
}
}
private class UnifiedNativeAdViewHolder extends RecyclerView.ViewHolder {
private View view;
public UnifiedNativeAdViewHolder(View view) {
super(view);
this.view = view;
}
}
}
日志上说 com.google.android.gms.internal.ads.zzaeh cannot be cast to mgb.com.sdalyricsplus.Database.Entities.SongsEntity 并将错误指向了viewbindholder。
case MENU_ITEM_VIEW_TYPE :
default:
SongItemViewHolder songItemViewHolder = (SongItemViewHolder)holder;
setSongViews(songItemViewHolder, (SongsEntity)recyclerViewItems.get(position)); // this line
我怀疑是视图类型。也许是视图类型没有正确分配。
我也试过这个代码，但错误仍然存在。
@Override
public int getItemViewType(int position) {
if (position % DisplayItemActivity.NUMBER_OF_AD == 0) {
return UNIFIED_NATIVE_AD_VIEW_TYPE;
}else {
return MENU_ITEM_VIEW_TYPE;
}
}
谁能帮我找到错误的原因？
你需要合并你的 SongItem 和 UnifiedNativeAd 成为1个单一的数据源。
制作一个新的对象类名 SongAdsData 合并你的 Song 对象和 Ads 从Admob变成1个单一的对象，如下图。
public class SongAdsData {
public int getType() {
return type;
}
public UnifiedNativeAd getAds() {
return ads;
}
public Post getSong() {
return Song;
}
public int type; // 1 is ads and 2 is songs
public UnifiedNativeAd ads;
public Song song; // here is ur Song object as usual
}
在你的适配器中，修改如下。
public class SongAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int UNIFIED_ADS_VIEW = 1;
private static final int SONG_ITEM_VIEW = 2;
private List<SongAdsData> songAdsDataList;
//here your onBindViewHolder,here your refer to item of `songAdsDataList`
// here your onCreateViewHolder
public void setSongAdsDataList(List<SongAdsData> songAdsDataForRecyclerView) {
this.songAdsDataList = songAdsDataForRecyclerView;
notifyDataSetChanged();
}
// Here is the function that insert the ads to RecyclerView
public void insertAdToRecyclerView(List<UnifiedNativeAds> nativeAds) {
int offset = songAdsDataList.size() / (nativeAds.size() + 1);
int index = 0;
for (UnifiedNativeAd ad : nativeAds) {
SongAdsData adsData = new SongAdsData();
adsData.song = null;
adsData.ads = ad;
adsData.type = 1; //1 for ads,2 for song
songAdsDataList.add(index,adsData);
index = index + offset;
}
notifyDataSetChanged();
}
@Override
public int getItemViewType (int position) {
if(songAdsDataList.get(position).getType() == 1){ // So here you compare the type of the object it the position
return UNIFIED_ADS;
}else{
return SONG_ITEM_VIEW;
}
}
@Override
public int getItemCount() {
if(songAdsDataList != null){
return songAdsDataList.size();
}else{
return 0;
}
}
}
最后在你的 DisplayItemActivity
我不知道你是如何获得SongItem的（你的数据从服务器或其他地方），但这个想法是转换你的 SongItem 变成 SongAdsData 我们在步骤一中创建的。
像这样的例子。
private void displaySongFromYourServer(List<Songs> songs) {
List<SongAdsData> songAdsDataList = new ArrayList<>();
for(Songs song : songs){
SongAdsData data = new SongAdsData();
data.ads = null;
data.song = song;
data.type = 2;
songAdsDataList.add(data);
}
songAdapter.setSongAdsDataList(songAdsDataList);
}
那么现在，你的 Song 项目将成为 SongAdsData. 同时，你的 UnifiedNativeAd 对象也需要改造成为 SongAdsData所以我们要把里面的东西都搬走 insertAdToList 变成 SongAdapter(见 insertAdToRecyclerView 在上面的歌曲适配器中），所以它可以引用相同的。List 的回收者视图。
因此，在你的 insertAdToList 的 DisplayItemActivity 应该变成这样。
private void insertAdToList() {
songAdapter.insertAdsToRecyclerView(nativeAds); //called to the function inside songAdapter.
}
希望你能明白我的意思
你需要覆盖 getItemViewType(int position) 来检查你的对象的实例，以便返回正确的视图类型。
@Override
public int getItemViewType(int position) {
if (this.recyclerViewItems.get(position) instanceof UnifiedNativeAd) {
return UNIFIED_NATIVE_AD_VIEW_TYPE;
}else {
return MENU_ITEM_VIEW_TYPE;
}
}