Java 使用RecyclerAdapter的Facebook原生广告

我正试图通过在我的RecyclerAdapter中将Facebook原生广告作为替代视图来实现。有人有过这方面的经验吗？我把全班同学都包括进来了

public class FeedRecyclerAdapter extends LoadingRowRecyclerAdapter implements AdListener {

    private static final int VIEW_TYPE_FEED = 1;
    private static final int VIEW_TYPE_AD = 2;

    private final Context context;
    private final List<Feed> feedItems;
    private final ImageLoader feedItemImageLoader;
    private FeedItemClickListener feedItemClickListener;
    private boolean isLongPressed = false;

    private NativeAd nativeAd;
    private NativeAdsManager manager;
    View adView;

    public FeedRecyclerAdapter(Context context, List<Feed> feedItems, ImageLoader feedItemImageLoader, NativeAd nativeAd, NativeAdsManager manager) {
        this.context = context;
        this.feedItems = feedItems;
        this.feedItemImageLoader = feedItemImageLoader;
        this.nativeAd = nativeAd;
        this.manager = manager;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        switch (viewType) {
            case VIEW_TYPE_FEED:
                return new FeedViewHolder(new FeedItemView(context));
            case VIEW_TYPE_AD:
                return new AdditionalHolder(LayoutInflater.from(context).inflate(R.layout.ad_test3, parent, false));
        }

        return super.onCreateViewHolder(parent, viewType);
    }

    public class AdditionalHolder extends RecyclerView.ViewHolder {
        protected LinearLayout templateContainer;
        protected ImageView blank_holder;
        private LinearLayout nativeAdContainer;
        private LinearLayout adView;
        private AdChoicesView adChoicesView;
        ImageView nativeAdIcon;
        TextView nativeAdTitle;
        TextView nativeAdBody;
        MediaView nativeAdMedia;
        TextView nativeAdSocialContext;
        Button nativeAdCallToAction;

        public AdditionalHolder(View view) {
            super(view);

            //// Add ad into the ad container.
            nativeAdContainer = (LinearLayout) view.findViewById(R.id.ad_unit);
            LayoutInflater inflater = LayoutInflater.from(context);
            adView = (LinearLayout) inflater.inflate(R.layout.ad_test3, nativeAdContainer, false);
            nativeAdContainer.addView(adView);

            // Create native UI using the ad metadata.
            nativeAdIcon = (ImageView) view.findViewById(R.id.native_ad_icon);
            nativeAdTitle = (TextView) view.findViewById(R.id.native_ad_title);
            nativeAdBody = (TextView) view.findViewById(R.id.native_ad_body);
            nativeAdMedia = (MediaView) view.findViewById(R.id.native_ad_media);
            nativeAdSocialContext = (TextView) view.findViewById(R.id.native_ad_social_context);
            nativeAdCallToAction = (Button) view.findViewById(R.id.native_ad_call_to_action);

        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
        if (getItemViewType(position) == VIEW_TYPE_FEED) {
            bindFeedItemView((FeedViewHolder) viewHolder, position);
        } else if (getItemViewType(position) == VIEW_TYPE_AD) {

            AdditionalHolder new_holder = (AdditionalHolder) viewHolder;
            try {
                new_holder.templateContainer.removeViewInLayout(adView);
            } catch (Exception e) {
                e.printStackTrace();
            }
            nativeAd = manager.nextNativeAd();
            try {
                adView = NativeAdView.render(context, nativeAd, NativeAdView.Type.HEIGHT_300);
            } catch (NullPointerException e) {
                e.printStackTrace();
            }

            new_holder.templateContainer.addView(adView);
            new_holder.blank_holder.setVisibility(View.GONE);

            // Setting the Text.
            new_holder.nativeAdSocialContext.setText(nativeAd.getAdSocialContext());
            new_holder.nativeAdCallToAction.setText(nativeAd.getAdCallToAction());
            new_holder.nativeAdTitle.setText(nativeAd.getAdTitle());
            new_holder.nativeAdBody.setText(nativeAd.getAdBody());

            // Downloading and setting the ad icon.
            NativeAd.Image adIcon = nativeAd.getAdIcon();
            NativeAd.downloadAndDisplayImage(adIcon, new_holder.nativeAdIcon);

            // Download and setting the cover image.
            NativeAd.Image adCoverImage = nativeAd.getAdCoverImage();
            new_holder.nativeAdMedia.setNativeAd(nativeAd);

            // Add adChoices icon
            if (new_holder.adChoicesView == null) {
                new_holder.adChoicesView = new AdChoicesView(context, nativeAd, true);
                new_holder.adView.addView(new_holder.adChoicesView, 0);
            }

            nativeAd.registerViewForInteraction(new_holder.adView);

        }
    }

    // Differentiate between feedItem views and nativeAds
    @Override
    public int getItemViewType(int position) {
        int viewType = 1;
        if ((position % 9 == 0) && position != 1) viewType = 2;
        return viewType;
    }

    // For feedItems
    private void bindFeedItemView(FeedViewHolder viewHolder, int position) {
        final FeedItemView feedItemView = viewHolder.feedItemView;
        final Feed feedDesign = feedItems.get(position);

        // TODO we can probably conditionally show or hide these based on the type of feed item, same as in FeedActivitySingle
        feedItemView.showOrHideEditButton(true);
        feedItemView.showOrHideBuyButton(false);
        feedItemView.showOrHideFlipButton(false);
        feedItemView.showOrHidePriceText(false);

        // Set the results into TextViews
        feedItemView.setProductPriceText(String.valueOf(feedDesign.getDesign().getPrice()));
        feedItemView.setDownloadsText(String.valueOf(feedDesign.getDesign().getDownloadCount()));
        feedItemView.setLikesText(String.valueOf(feedDesign.getDesign().getLikesCount()));
        feedItemView.setUsernameText(feedDesign.getDesign().getAuthor().getUsername());
        feedItemView.setTimestampText(feedDesign.getTimestampText());
        feedItemView.getSaveImage().setImageResource(feedDesign.isInPersonalGallery() ? R.drawable.ic_action_saved : R.drawable.ic_not_saved);
        feedItemView.getLikeImage().setImageResource(feedDesign.isLiked() ? R.drawable.ic_action_like_feed_full : R.drawable.ic_action_like_feed);

        feedItemView.getTrashImage().setVisibility(ParseHelper.isCurrentUser(feedDesign.getDesign().getAuthor().getObjectId()) ? View.VISIBLE : View.GONE);
        feedItemView.getFeedSocialShareImage().setVisibility(View.VISIBLE);

        feedItemImageLoader.DisplayImage(feedDesign.getDesign().getCompressedImage().getUrl(), feedItemView.getImage(), feedItemView.getProgressBar());

        if(feedDesign.getDesign().getAuthor().getProfilePicture() != null) {
            feedItemImageLoader.DisplayImage(feedDesign.getDesign().getAuthor().getProfilePicture().getUrl(), feedItemView.getProfilePicture(), null); // TODO should this use profilePictureFileCache?
        } else {
            viewHolder.feedItemView.getProfilePicture().setImageResource(R.drawable.ic_anonymous);
        }

        SetCommentViews(feedItemView, feedDesign.getComments());
        SetClickListeners(feedItemView, feedDesign);
    }

    @Override
    protected int getContentDataSize() {
        return feedItems.size();
    }

    @Override
    protected int getViewType(int position) {
        if (position == 1) {
            return VIEW_TYPE_FEED;
        } else {
            return VIEW_TYPE_AD;
        }
    }

    // Facebook Ad methods
    @Override
    public void onError(Ad ad, AdError adError) {

    }

    @Override
    public void onAdLoaded(Ad ad) {

    }

    @Override
    public void onAdClicked(Ad ad) {

    }

    public void setFeedItemClickListener(FeedItemClickListener feedItemClickListener) {
        this.feedItemClickListener = feedItemClickListener;
    }

    private void SetCommentViews(FeedItemView feedItemView, List<Comment> comments) {

        feedItemView.getViewAllComments().setVisibility(View.VISIBLE);
        feedItemView.setViewAllComments("View more comments");

        // reset layouts to hidden
        feedItemView.getComment1Layout().setVisibility(View.GONE);
        feedItemView.getComment2Layout().setVisibility(View.GONE);
        feedItemView.getComment3Layout().setVisibility(View.GONE);

        if (comments == null || comments.size() == 0) {
            feedItemView.getViewAllComments().setVisibility(View.GONE);
            return;
        }

        // note these are meant to fall-through without break statements
        switch (comments.size()) {
            case 3:
                feedItemView.getComment3Layout().setVisibility(View.VISIBLE);
                feedItemView.setCommentUser3(comments.get(2).getAuthor().getUsername());
                feedItemView.setCommentText3(comments.get(2).getComment());
            case 2:
                feedItemView.getComment2Layout().setVisibility(View.VISIBLE);
                feedItemView.setCommentUser2(comments.get(1).getAuthor().getUsername());
                feedItemView.setCommentText2(comments.get(1).getComment());
            case 1:
                feedItemView.getComment1Layout().setVisibility(View.VISIBLE);
                feedItemView.setCommentUser1(comments.get(0).getAuthor().getUsername());
                feedItemView.setCommentText1(comments.get(0).getComment());
                break;
        }
    }

    private void SetClickListeners(final FeedItemView feedItemView, final Feed feedDesign) {

        // setup gesture detector with current view, view holder, and feed design
        final GestureDetector gestureDetector = new GestureDetector(context, new GestureListener(feedDesign, feedItemView));

        // set gesture detector on image view
        feedItemView.setImageTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                if (motionEvent.getAction() == ACTION_UP){
                    if (isLongPressed){
                        isLongPressed = false;
                        feedItemClickListener.onMarkteFeedImageLongPressed_Release();
                        Log.d("anyTAG","Up");
                        return true;
                    }
                }
                if (motionEvent.getAction() == ACTION_MOVE){
                    return true;
                }
                return gestureDetector.onTouchEvent(motionEvent);
            }
        });

        feedItemView.setTrashImageClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onTrashClicked(feedDesign);
            }
        });

        feedItemView.setFeedSocialShareClickListener(v -> {
            if (feedItemClickListener != null) {
                try {
                    feedItemClickListener.onSocialShareClicked(feedDesign);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

        feedItemView.setLikeImageClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onLikeClicked(feedDesign, feedItemView);
            }
        });

        feedItemView.setSaveImageClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onSaveClicked(feedDesign, feedItemView);
            }
        });

        feedItemView.setAuthorClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onAuthorClicked(feedDesign);
            }
        });

        feedItemView.setCommentTextClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onCreateCommentClicked(feedDesign);
            }
        });

        feedItemView.setViewAllCommentsClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onCreateCommentClicked(feedDesign);
            }
        });

        feedItemView.setEditImageClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onCreateEditImageClicked(feedDesign);
            }
        });

        feedItemView.setCommentImageClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onCreateCommentClicked(feedDesign);
            }
        });

        feedItemView.setCommentUser1ClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onAuthorClicked(feedDesign.getComments().get(0).getAuthor().getObjectId());
            }
        });

        feedItemView.setCommentUser2ClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onAuthorClicked(feedDesign.getComments().get(1).getAuthor().getObjectId());
            }
        });

        feedItemView.setCommentUser3ClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onAuthorClicked(feedDesign.getComments().get(2).getAuthor().getObjectId());
            }
        });

        feedItemView.setProfilePictureClickListener(v -> {
            if (feedItemClickListener != null) {
                feedItemClickListener.onProfilePictureClicked(feedDesign);
            }
        });

    }

    class FeedViewHolder extends RecyclerView.ViewHolder {

        FeedItemView feedItemView;

        public FeedViewHolder(FeedItemView view) {
            super(view);
            this.feedItemView = view;
        }

    }

    // Gesture detector for double tap
    private class GestureListener extends GestureDetector.SimpleOnGestureListener {

        private Feed feedDesign;
        private FeedItemView feedItemView;

        public GestureListener(Feed feedDesign, FeedItemView feedItemView) {
            this.feedDesign = feedDesign;
            this.feedItemView = feedItemView;
        }

        @Override
        public boolean onDown(MotionEvent e) {
            return true;
        }

        @Override
        public boolean onDoubleTap(MotionEvent event) {
            Log.d("FeedRecyclerAdapter", feedDesign.getDesign().getCompressedImage().getUrl());

            if (feedItemClickListener != null) {
                feedItemClickListener.onImageDoubleTapped(feedDesign, feedItemView);
            }

            return true;
        }

        @Override
        public void onLongPress(MotionEvent event) {

            if (event.getAction() == ACTION_DOWN)
            {
                if (!isLongPressed){
                    isLongPressed = true;
                    feedItemClickListener.onMarketFeedImageLongPressed(feedDesign, feedDesign.getDisplayedSide());
                }
            }
        }
    }
}

首先，它似乎在抱怨这句话：

nativeAd = manager.nextNativeAd();

以下是我的FeedActivity课程的要点：

nativeAd = manager.nextNativeAd();

---

当您试图调用对象引用的方法或访问该引用的字段，但该引用不包含有效对象时，会发生

NullPointerException

。一个简单的例子是：

String someString;
char firstChar = someString.charAt(0); // ERROR!

此代码引发错误，因为调用

charAt

时，

someString

变量未引用有效的

String

实例。请注意，第一行没有创建

字符串
实例，它只声明一个可能指向
字符串的变量。事实上，该代码相当于：

有关
NullPointerException
s的详细信息，请了解它们发生的原因以及如何修复它们：

在您的情况下，错误是由以下原因引起的：

这里，
manager
是
FeedActivity
类的一个实例字段，定义在：

问题是，此字段从未分配值：此字段没有分配值（例如
manager=…
）。因此，当执行第176行时，
FeedRecyclerAdapter
将
null
作为其
manager
参数接收，并在稍后尝试使用该
manager
时在
onBindViewHolder
中抛出
NullPointerException

解决方案是在
FeedActivity
中创建一个有效的
nativeadmanager
，并将其分配给
manager
，然后将其传递给
FeedRecyclerAdapter
，此类代码应如下所示：

public class YourActivity extends Activity implements NativeAdsManager.Listener {

    private NativeAdsManager manager; 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_layout);

        manager = new NativeAdsManager(this, "YOUR_PLACEMENT_ID", 5);
        manager.setListener(this);
        manager.loadAds();

    }
}

当您试图调用
nextnativeead
时，该错误表示
manager
为
null
。您应该仔细检查是否确实向构造函数传递了有效的管理器。我如何确定？您可以先查看调用新FeedRecyclerAdapter（…）
的位置，然后检查是否无意中将文本
null
值作为
管理器
参数传递给构造函数。如果您没有立即看到为什么会出现
null
，请连接调试器以更好地了解程序运行时的情况。这里有很多好的建议。如果您仍然无法理解，请更新您的代码以添加更多代码，以便其他人可以尝试帮助您。我在FeedActivity的onCreate方法中调用此构造函数，该方法与我的FeedRecyclerAdapter分开：
FeedRecyclerAdapter=new FeedRecyclerAdapter（this，feedItems，new ImageLoader（new FeedItemFileCache，this）），本地人，经理）。如果您想查看，我在编辑中添加了该活动。谢谢，在主提要活动中初始化是有意义的。至少解决了这个异常！
feedRecyclerAdapter = new FeedRecyclerAdapter(this, feedItems, new ImageLoader(new FeedItemFileCache(this)), nativeAd, manager);

public NativeAdsManager manager;

public class YourActivity extends Activity implements NativeAdsManager.Listener {

    private NativeAdsManager manager; 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_layout);

        manager = new NativeAdsManager(this, "YOUR_PLACEMENT_ID", 5);
        manager.setListener(this);
        manager.loadAds();

    }
}