Android ListView重复图像

我正在android上实现一个包含imageview的listview，我遇到了一个问题： 当一行没有图像时，它会重复上一项的图像

这是我的适配器：

    public class NewsAdapter extends BaseAdapter {
        private final LayoutInflater inflater;
        private final Context context;
        private List<News> newsList;

        public NewsAdapter(List<News> newsList, Context context) {
            this.newsList = newsList;
            this.context = context;
            inflater = LayoutInflater.from(context);
        }

        ...         

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            final ViewHolder viewHolder;
            if (convertView == null) {
                LayoutInflater row = (LayoutInflater) this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = row.inflate(R.layout.image_new_row, null);

                viewHolder = new ViewHolder();
                viewHolder.mTitle = convertView.findViewById(R.id.txtNewsTitle);
                viewHolder.mImage = convertView.findViewById(R.id.imageNews);
                viewHolder.mDescription = convertView.findViewById(R.id.txtDescription);

                convertView.setTag(viewHolder);
            } else {
                viewHolder = (ViewHolder) convertView.getTag();
            }

            News news = newsList.get(position);
            viewHolder.mTitle.setText(news.getTitle());
            viewHolder.mDescription.setText(news.getDescription());
            if (news.getImageUrl() != null){
                ImageLoader.getInstance().displayImage(news.getImageUrl(), viewHolder.mImage);
            }
            else{
                viewHolder.mImage.setImageResource(R.drawable.loading);
            }

            return convertView;
        }

我的活动：

        public class NewsActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {

            private static final String ITEM = "item";
            private static final String TITLE = "title";
            private static final String LINK = "link";
            private static final String DESCRIPTION = "description";
            private static final String MEDIA = "media:content";
            private static final String IMAGE_URL = "url";

            private Feed feed;
            private ListView newsListView;
            private ArrayList<News> newsList;
            private NewsAdapter mAdapter;
            private ImageLoaderConfiguration imageLoaderConfiguration;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_news);

                newsListView = (ListView) findViewById(R.id.newsList);

                this.feed = (Feed) getIntent().getSerializableExtra(Constants.EXTRA_CLICKED_FEED);

                configListView();
            }

            private void configListView() {
                File cacheDir = StorageUtils.getCacheDirectory(this);

                DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
                        .showImageForEmptyUri(R.drawable.loading)
                        .showImageOnLoading(R.drawable.loading)
                        .showImageOnFail(R.drawable.loading).cacheInMemory(true).cacheOnDisk(true).build();
                imageLoaderConfiguration = new ImageLoaderConfiguration.Builder(this)
                        .defaultDisplayImageOptions(defaultOptions).build();
                ImageLoader.getInstance().init(imageLoaderConfiguration);

                newsList = new ArrayList<News>();
                mAdapter = new NewsAdapter(newsList, this);
                newsListView.setAdapter(mAdapter);

                newsListView.setOnItemClickListener(this);

                new RssAsyncTask().execute(
                        feed.getUrl());
            }

            private List<News> readXML(InputStream is) {
                List<News> newsList =
                        new ArrayList<News>();

                try {
                    DocumentBuilderFactory factory =
                            DocumentBuilderFactory.newInstance();

                    DocumentBuilder builder =
                            factory.newDocumentBuilder();
                    Document xmlDocument = builder.parse(is);

                    NodeList posts =
                            xmlDocument.getElementsByTagName(ITEM);

                    String title = null, description = null,
                            link = null, image = null;

                    for (int i = 0; i < posts.getLength(); i++) {
                        Node post = posts.item(i);

                        // Cada nó ITEM tem os filhos:
                        // TITLE, DESCRIPTION e LINK
                        NodeList postInfo = post.getChildNodes();

                        for (int j = 0; j < postInfo.getLength(); j++) {
                            Node info = postInfo.item(j);

                            if (TITLE.equals(info.getNodeName())) {
                                title = info.getTextContent();

                            } else if (LINK.equals(
                                    info.getNodeName())) {
                                link = info.getTextContent();

                            } else if (DESCRIPTION.equals(
                                    info.getNodeName())) {
                                description = extractText(info.getTextContent()).trim();
                            } else if (MEDIA.equals(
                                    info.getNodeName())) {
                                image = ((Element) info).getAttribute(IMAGE_URL);
                            }
                        }
                        newsList.add(
                                new News(title, description, link, image));
                    }
                } catch (Throwable e) {
                    e.printStackTrace();
                }
                return newsList;
            }


            class RssAsyncTask extends
                    AsyncTask<String, Void, List<News>> {

                ProgressDialog dialog;

                ...

                @Override
                protected void onPostExecute(List<News> result) {
                    super.onPostExecute(result);
                    dialog.dismiss();
                    newsList.addAll(result);
                    mAdapter.notifyDataSetChanged();
                }


            }
        }

公共类NewsActivity扩展AppCompativeActivity实现AdapterView.OnItemClickListener{
私有静态最终字符串ITEM=“ITEM”；
私有静态最终字符串TITLE=“TITLE”；
私有静态最终字符串LINK=“LINK”；
私有静态最终字符串DESCRIPTION=“DESCRIPTION”；
私有静态最终字符串MEDIA=“MEDIA:content”；
私有静态最终字符串IMAGE\u URL=“URL”；
私人饲料；
私有ListView新闻ListView；
私有ArrayList新闻列表；
私人新闻适配器；
私有ImageLoader配置ImageLoader配置；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_news）；
newsListView=（ListView）findViewById（R.id.newsList）；
this.feed=（feed）getIntent（）.getSerializableExtra（Constants.EXTRA_单击了_feed）；
configListView（）；
}
私有void configListView（）{
文件cacheDir=StorageUtils.getCacheDirectory（this）；
DisplayImageOptions defaultOptions=新建DisplayImageOptions.Builder（）
.showImageForEmptyUri（R.可牵引装载）
.showImageOnLoading（R.可绘制.加载）
.showImageOnFail（R.drawable.loading）.cacheInMemory（true）.cacheOnDisk（true）.build（）；
imageLoaderConfiguration=新建imageLoaderConfiguration.Builder（此）
.defaultDisplayImageOptions（defaultOptions）.build（）；
ImageLoader.getInstance（）.init（imageLoaderConfiguration）；
newsList=newarraylist（）；
mAdapter=新的新闻适配器（新闻列表，此）；
setAdapter（mAdapter）；
setOnItemClickListener（这个）；
新建RssAsyncTask（）。执行(
feed.getUrl（））；
}
私有列表readXML（InputStream为）{
列表新闻列表=
新的ArrayList（）；
试一试{
文档建设者工厂=
DocumentBuilderFactory.newInstance（）；
文档生成器=
factory.newDocumentBuilder（）；
Document xmlDocument=builder.parse（is）；
节点列表帖子=
xmlDocument.getElementsByTagName（项目）；
字符串title=null，description=null，
link=null，image=null；
对于（int i=0；i

obs：我正在使用通用映像加载api：

---

当然了。。。您正在重用上一个项目的布局。这就是下面这句话的意思

viewHolder = (ViewHolder) convertView.getTag();

---

如果您没有在

getView

方法中初始化它，它将显示与上一项相同的内容。

从您的代码中-当图像下载失败时，可能会发生这种情况。 您可以使用：

viewHolder.mImage.setImageResource(R.drawable.loading);        
if (news.getImageUrl() != null){
    ImageLoader.getInstance().displayImage(news.getImageUrl(), viewHolder.mImage);
}

或

您可以使用以下代码：

ImageLoader.getInstance().displayImage(imageUri, imageView, options, new ImageLoadingListener() {
    @Override
    public void onLoadingStarted(String imageUri, View view) {
    ...
    }
    @Override
    public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
        ...
    }
    @Override
    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
        ...
    }
    @Override
    public void onLoadingCancelled(String imageUri, View view) {
        ...
    }
}
});

---

将变量初始化放入for循环中，如下所示，这样每次它都会将变量重新初始化为null

                for (int i = 0; i < posts.getLength(); i++) {

                       String title = null, description = null,
                        link = null, image = null;

                    Node post = posts.item(i);

                    // Cada nó ITEM tem os filhos:
                    // TITLE, DESCRIPTION e LINK
                    NodeList postInfo = post.getChildNodes();

                    for (int j = 0; j < postInfo.getLength(); j++) {
                        Node info = postInfo.item(j);

                        if (TITLE.equals(info.getNodeName())) {
                            title = info.getTextContent();

                        } else if (LINK.equals(
                                info.getNodeName())) {
                            link = info.getTextContent();

                        } else if (DESCRIPTION.equals(
                                info.getNodeName())) {
                            description = extractText(info.getTextContent()).trim();
                        } else if (MEDIA.equals(
                                info.getNodeName())) {
                            image = ((Element) info).getAttribute(IMAGE_URL);
                        }
                    }
                    newsList.add(
                            new News(title, description, link, image));
                }

for（int i=0；i                for (int i = 0; i < posts.getLength(); i++) {

                       String title = null, description = null,
                        link = null, image = null;

                    Node post = posts.item(i);

                    // Cada nó ITEM tem os filhos:
                    // TITLE, DESCRIPTION e LINK
                    NodeList postInfo = post.getChildNodes();

                    for (int j = 0; j < postInfo.getLength(); j++) {
                        Node info = postInfo.item(j);

                        if (TITLE.equals(info.getNodeName())) {
                            title = info.getTextContent();

                        } else if (LINK.equals(
                                info.getNodeName())) {
                            link = info.getTextContent();

                        } else if (DESCRIPTION.equals(
                                info.getNodeName())) {
                            description = extractText(info.getTextContent()).trim();
                        } else if (MEDIA.equals(
                                info.getNodeName())) {
                            image = ((Element) info).getAttribute(IMAGE_URL);
                        }
                    }
                    newsList.add(
                            new News(title, description, link, image));
                }