我正在尝试按照Admob车库教程在RecyclerView中实施原生广告。但我收到错误说＆＃34;错误：不兼容的类型：命中无法转换为NativeExpressAdView＆＃34;
在setUpAndLoadNativeExpressAds中说＆＃34; Casting＆＃39; hit.get（i）＆＃39;到＃NativeDpressAdView＆＃39;是多余的。此检查报告不必要的演员表达。＆＃34;
（错误在onBindViewHolder上，注释// ERROR Lines //为了更好地理解。）
这是我的班级
package com.example.wallpaper.app.ui.adapter;
import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import com.example.wallpaper.app.model.Hit;
import com.example.wallpaper.app.model.Pic;
import com.example.wallpaper.app.ui.DiscoverFragment;
import com.example.wallpaper.app.ui.PicDetail;
import com.example.wallpaper.app.R;
import com.example.wallpaper.app.ui.util.WallpaperViewHolder;
import com.google.android.gms.ads.NativeExpressAdView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import java.util.List;
public class WallpaperAdapter extends RecyclerView.Adapter<WallpaperViewHolder> {
private List<Hit> hit;
private Context context;
public int width;
public int height;
public static final int IMAGE__LIST_ITEMS = 0;
public static final int NATIVE_EXPRESS_AD_VIEW_TYPE = 1;
public WallpaperAdapter (Context context){
this.context=context;
this.hit=new ArrayList<>();
}
public class NativeExpressAdViewHolder extends WallpaparViewHolder {
NativeExpressAdViewHolder(View view) {
super(view);
}
}
@Override
public int getItemViewType(int position)
{
return (position % DiscoverFragment.ITEMS_PER_AD == 0)? NATIVE_EXPRESS_AD_VIEW_TYPE : IMAGE__LIST_ITEMS;
}
@Override
public int getItemCount()
{
return (hit == null) ? 0 : hit.size();
}
@Override
public WallpaperViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
switch (viewType){
case IMAGE__LIST_ITEMS:
View itemView = LayoutInflater.from(context).inflate(R.layout.wallp_item, null);
final WallpaperViewHolder rcv=new WallpaperViewHolder(itemView);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
int position = rcv.getAdapterPosition();
Intent intent = new Intent(context, PicDetail.class);
intent.putExtra(PicDetail.EXTRA_PIC, hit.get(position));
context.startActivity(intent);
}
});
return rcv;
case NATIVE_EXPRESS_AD_VIEW_TYPE:
default:
View nativeExpressLayoutView = LayoutInflater.from(
viewGroup.getContext()).inflate(R.layout.native_express_ad_container,
viewGroup, false);
return new WallpaperViewHolder(nativeExpressLayoutView);
}
}
@Override
public void onBindViewHolder(WallpaperViewHolder holder, int position) {
int viewType = getItemViewType(position);
switch (viewType){
case IMAGE__LIST_ITEMS:
Hit photo = this.hit.get(position);
RelativeLayout.LayoutParams rlp = (RelativeLayout.LayoutParams) holder.discWallp.getLayoutParams();
float height =photo.getPreviewHeight();
float width = photo.getPreviewWidth();
float ratio = height/width ;
rlp.height = (int) (rlp.width * ratio);
holder.discWallp.setLayoutParams(rlp);
holder.discWallp.setRatio(ratio);
Picasso.with(context)
.load(photo.getWebformatURL())
.placeholder(R.drawable.plh)
.into(holder.discWallp);
break;
case NATIVE_EXPRESS_AD_VIEW_TYPE:
default:
**// ERROR Lines// // ERROR Lines// // ERROR Lines// // ERROR Lines//**
NativeExpressAdViewHolder nativeExpressHolder;
nativeExpressHolder = (NativeExpressAdViewHolder) holder;
NativeExpressAdView adView;
adView = (NativeExpressAdView) hit.get(position);
**// ERROR Lines// // ERROR Lines// // ERROR Lines// // ERROR Lines//**
ViewGroup adCardView = (ViewGroup) nativeExpressHolder.itemView;
if (adCardView.getChildCount() > 0) {
adCardView.removeAllViews();
}
if (adView.getParent() != null) {
((ViewGroup) adView.getParent()).removeView(adView);
}
adCardView.addView(adView);
}
}
public void setPicList(Pic picList)
{
if(picList.getHits()!=null)
this.hit.addAll(picList.getHits());
notifyDataSetChanged();
}
}
片段在这里
public class DiscoverFragment extends Fragment implements AsyncResponse {
public WallpaperAdapter WallpaperAdapter ;
public RecyclerView recyclerView;
public NetworkUtilities networkUtilities;
public EndlessRecyclerViewScrollListener scrollListener;
public WallpService wallpService;
public int column_no;
public static final int ITEMS_PER_AD = 4;
// List of Native Express ads and MenuItems that populate the RecyclerView.
private ArrayList<Object> hit = new ArrayList<>();
private static final int NATIVE_EXPRESS_AD_HEIGHT = 150;
// The Native Express ad unit ID.
private static final String AD_UNIT_ID = "ca-app-pub-xxxxxxxxxx543";
public static DiscoverFragment newInstance() {
DiscoverFragment fragment = new DiscoverFragment();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
networkUtilities = new NetworkUtilities(getActivity());
recyclerView = (RecyclerView) getActivity().findViewById(R.id.discRecView);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
loadNextDataFromApi(1);
addNativeExpressAds();
setUpAndLoadNativeExpressAds();
}
private void addNativeExpressAds() {
// Loop through the items array and place a new Native Express ad in every ith position in
// the items List.
for (int i = 0; i <= hit.size(); i += ITEMS_PER_AD) {
final NativeExpressAdView adView = new NativeExpressAdView(getActivity()
.getApplicationContext());
hit.add(i, adView);
}
}
private void setUpAndLoadNativeExpressAds() {
// Use a Runnable to ensure that the RecyclerView has been laid out before setting the
// ad size for the Native Express ad. This allows us to set the Native Express ad's
// width to match the full width of the RecyclerView.
recyclerView.post(new Runnable() {
@Override
public void run() {
final float scale = getActivity().getApplicationContext()
.getResources().getDisplayMetrics().density;
// Set the ad size and ad unit ID for each Native Express ad in the items list.
for (int i = 0; i <= hit.size(); i += ITEMS_PER_AD) {
final NativeExpressAdView adView =
(NativeExpressAdView) hit.get(i);
final CardView cardView = (CardView) getActivity().findViewById(R.id.ad_card_view);
final int adWidth = cardView.getWidth() - cardView.getPaddingLeft()
- cardView.getPaddingRight();
AdSize adSize = new AdSize((int) (adWidth / scale), NATIVE_EXPRESS_AD_HEIGHT);
adView.setAdSize(adSize);
adView.setAdUnitId(AD_UNIT_ID);
}
// Load the first Native Express ad in the items list.
loadNativeExpressAd(0);
}
});
}
private void loadNativeExpressAd(final int index) {
if (index >= hit.size()) {
return;
}
Object item = hit.get(index);
if (!(item instanceof NativeExpressAdView)) {
throw new ClassCastException("Expected item at index " + index + " to be a Native"
+ " Express ad.");
}
final NativeExpressAdView adView = (NativeExpressAdView) item;
// Set an AdListener on the NativeExpressAdView to wait for the previous Native Express ad
// to finish loading before loading the next ad in the items list.
adView.setAdListener(new AdListener() {
@Override
public void onAdLoaded() {
super.onAdLoaded();
// The previous Native Express ad loaded successfully, call this method again to
// load the next ad in the items list.
loadNativeExpressAd(index + ITEMS_PER_AD);
}
@Override
public void onAdFailedToLoad(int errorCode) {
// The previous Native Express ad failed to load. Call this method again to load
// the next ad in the items list.
Log.e("MainActivity", "The previous Native Express ad failed to load. Attempting to"
+ " load the next Native Express ad in the items list.");
loadNativeExpressAd(index + ITEMS_PER_AD);
}
});
// Load the Native Express ad.
adView.loadAd(new AdRequest.Builder().build());
}
@Override
public void onResume() {
super.onResume();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(!networkUtilities.isInternetConnectionPresent()){
return inflater.inflate(R.layout.fragment_no_internet, container, false);
}
else{
View view = inflater.inflate(R.layout.fragment_discover, container, false);
recyclerView=(RecyclerView) view.findViewById(R.id.discRecView);
recyclerView.setHasFixedSize(true);
checkScreenSize();
StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(column_no,StaggeredGridLayoutManager.VERTICAL);
recyclerView.setLayoutManager(staggeredGridLayoutManager);
scrollListener = new EndlessRecyclerViewScrollListener(staggeredGridLayoutManager) {
@Override
public void onLoadMore(int page, int totalItemsCount, RecyclerView view) {
loadNextDataFromApi(page);
}
};
scrollListener.resetState();
recyclerView.addOnScrollListener(scrollListener);
WallpaperAdapter = new WallpaperAdapter (getActivity());
recyclerView.setAdapter(WallpaperAdapter );
return view;
}
}
@Override
public void processFinish(Pic output) {
if (output.getHits() != null) {
WallpaperAdapter .setPicList(output);
}
}
public void loadNextDataFromApi(int offset) {
String type=getResources().getString(R.string.popular);
wallpService = new WallpService(networkUtilities, getActivity(), this,offset,type);
wallpService.loadWallp();
}
public void checkScreenSize() {
int screenSize = getResources().getConfiguration().screenLayout &
Configuration.SCREENLAYOUT_SIZE_MASK;
switch (screenSize) {
case Configuration.SCREENLAYOUT_SIZE_XLARGE:
column_no = 3;
break;
case Configuration.SCREENLAYOUT_SIZE_UNDEFINED:
column_no = 2;
break;
case Configuration.SCREENLAYOUT_SIZE_LARGE:
column_no = 2;
break;
case Configuration.SCREENLAYOUT_SIZE_NORMAL:
column_no = 1;
break;
case Configuration.SCREENLAYOUT_SIZE_SMALL:
column_no = 1;
break;
default:
column_no = 1;
}
}
}
答案 0 :(得分：0)
您的hit变量属于List<Hit>类型。所以它显然只有Hit个对象。
此代码：
adView = (NativeExpressAdView) hit.get(position);
会失败，因为该对象不可能是NativeExpressAdView。
要实现这一目标，您需要将列表设为Object类型，并在NativeExpressAdView对象中实际广告，类似于其完成方式here。我建议下载并播放这个示例，并将其中的部分移动到您的代码中以使其正常工作。