Android - 适配器的内容已更改？

时间：2015-05-11 21:24:43

标签： android listview android-asynctask

我正在努力让我的无尽列表工作但是我总是得到关于修改适配器内容的IllegalStateException。我完全不知道为什么会这样。

错误非常

IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread. [in ListView(2131493058, class android.widget.ListView) with Adapter(class ListNewsAdapter)]

这是我的AsyncTask：

public class ListDownloadNewAsyncTask extends AsyncTask<Void, Void, NewsArrayList> {
    private String mLastId = null;

    @Override
    protected void onPreExecute() {
        ListNewsAdapter adapter = (ListNewsAdapter) listView.getAdapter();
        if (adapter != null && adapter.getCount() > 0) {
            mLastId = adapter.getItem(adapter.getCount() - 1).getId();
        }
        super.onPreExecute();
    }

    @Override
    protected NewsArrayList doInBackground(Void... params) {
        NewsArrayList downloadedNews = null;
        try {
            downloadedNews = JSONLoader.loadNews(getActivity(), mLastId);
        } catch (Exception ex) { }
        return downloadedNews;
    }

    @Override
    protected void onPostExecute(NewsArrayList result) {
        mLeftToDownload = result.getLeft();
        ListNewsAdapter adapter = (ListNewsAdapter) listView.getAdapter();
        if (adapter == null) {
            adapter = new ListNewsAdapter(getActivity(), R.layout.news_list_row, result.getNewsArray(), NewsListFragment.this);
            listView.setAdapter(adapter);
        } else {
            adapter.addAll(result.getNewsArray());
            adapter.notifyDataSetChanged();
            isLoading = false;
        }
        super.onPostExecute(result);
    }
}

我正在搜索有关无限listView的任何代码段，但我发现的大部分内容都是静态或动态创建的 - 未下载。

所以我的问题是......我在这里错过了什么？或者我做错了什么？

编辑：这是我的适配器类

public class ListNewsAdapter extends ArrayAdapter<News> {
private final ArrayList<News> news;
private final int newsRowResourceId;
private View progressView;
NewsListFragment fragment;

public ListNewsAdapter(Context context, int newsRowResourceId, ArrayList<News> news, NewsListFragment fragment) {
    super(context, newsRowResourceId, news);
    this.news = news;
    this.newsRowResourceId = newsRowResourceId;
    this.fragment = fragment;
}

@Override
public int getCount() {
    return NewsListFragment.isLoading() ? news.size() + 1 : news.size();
}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    ViewHolder holder;

    try {
        if (convertView == null || convertView.findViewById(R.id.title) != null || convertView == progressView) {

            convertView = inflater.inflate(newsRowResourceId, null);
            holder = new ViewHolder();
            holder.title = (TextView) convertView.findViewById(R.id.title);
            holder.description = (TextView) convertView.findViewById(R.id.description);
            holder.image = (ImageView) convertView.findViewById(R.id.news_list_item_image);

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

        if (position < getCount()) {
            News newsRow = news.get(position);

            if (newsRow != null) {
                holder.title.setText(newsRow.getTitle().trim().replaceAll("[\n\r]", " "));
                holder.description.setText(newsRow.getDescription().trim().replaceAll("[\n\r]", " "));

                if (newsRow.getPhotoUrl() != null && !newsRow.getPhotoUrl().equalsIgnoreCase("null")) {
                    Ion.with(holder.image).placeholder( R.drawable.icon ).load(newsRow.getPhotoUrl());
                } else {
                    holder.image.setImageResource(R.drawable.icon);
                }
            }
        }
        convertView.setClickable(true);
        convertView.setFocusable(true);
        convertView.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Main.instance.changeNewsFragment(news.get(position).getNewsUrl());
            }
        });

        return convertView;

    } catch (IndexOutOfBoundsException e) {
        progressView = inflater.inflate(R.layout.progress_list_item, null);
        return progressView;
    }
}

static class ViewHolder {
    TextView title;
    TextView description;
    ImageView image;
}
}
编辑：我想了一件事。我从OnScrollListener启动asynctask：

public abstract class InfiniteScrollListener implements AbsListView.OnScrollListener {
    private int bufferItemCount = 10;

    public InfiniteScrollListener(int bufferItemCount) {
        this.bufferItemCount = bufferItemCount;
    }

    public abstract void loadMore();

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        if ((mLeftToDownload > 0) && !isLoading && ((firstVisibleItem + visibleItemCount) >= (totalItemCount - bufferItemCount))) {
            Log.d("test", "from onScroll: " + mLeftToDownload + ", " + isLoading + ", " + (firstVisibleItem + visibleItemCount) + ">=" + (totalItemCount - bufferItemCount));
            isLoading = true;
            loadMore();
        }
    }
}

和

public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.news_list_fragment, null);
    listView = (ListView) v.findViewById(R.id.list_news);

    mLeftToDownload = -1;

    listView.setOnScrollListener(new InfiniteScrollListener(5) {
        @Override
        public void loadMore() {
            new ListDownloadNewAsyncTask().execute();
        }
    });
    listView.setItemsCanFocus(true);

    new ListDownloadNewAsyncTask().execute();

    return v;
}

所以我认为它可能是两个任务在同一个适配器上运行的东西。所以我在if方法中修改了onscroll语句的最后一部分，这减少了崩溃的数量，但我仍然有一些。

编辑：Logget for @Elltz 

05-12 00:58:51.027    5108-5108/app.packg E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread. [in ListView(2131493058, class android.widget.ListView) with Adapter(class ListNewsAdapter)]
        at android.widget.ListView.layoutChildren(ListView.java:1538)
        at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:4385)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
        at android.view.Choreographer.doCallbacks(Choreographer.java:555)
        at android.view.Choreographer.doFrame(Choreographer.java:524)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
        at android.os.Handler.handleCallback(Handler.java:615)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4849)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
        at dalvik.system.NativeStart.main(Native Method)

1 个答案:

答案 0 :(得分：0)

好的，在分析了你的代码后，这似乎是一个有效的解决方案，试试这个：

1.将此方法添加到适配器

public void addNewData(ArrayList<News> newData) {
    if(news != null) {
        news.addAll(newData);
        notifyDataSetChanged();
    }
}

2.用此

替换onPostExecute 
@Override
protected void onPostExecute(NewsArrayList result) {
    mLeftToDownload = result.getLeft();
    ListNewsAdapter adapter = (ListNewsAdapter) listView.getAdapter();
    if (adapter == null) {
        adapter = new ListNewsAdapter(getActivity(), R.layout.news_list_row, result.getNewsArray(), NewsListFragment.this);
        listView.setAdapter(adapter);
    } else {
        adapter.addNewData(result.getNewsArray());
        isLoading = false;
    }
    super.onPostExecute(result);
}

希望这会有所帮助

编辑所以显然它不起作用，所以最后的办法是改变适配器

public class ListNewsAdapter extends BaseAdapter {
private final ArrayList<News> news;
private View progressView;
NewsListFragment fragment;

LayoutInflater inflater;

public ListNewsAdapter(Context context, NewsListFragment fragment) {
    this.fragment = fragment;
    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    if(news == null)
         return 0;
    return NewsListFragment.isLoading() ? news.size() + 1 : news.size();
}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    ViewHolder holder;

    try {
        if (convertView == null || convertView.findViewById(R.id.title) != null || convertView == progressView) {

            convertView = inflater.inflate(R.layout.news_list_row, null);
            holder = new ViewHolder();
            holder.title = (TextView) convertView.findViewById(R.id.title);
            holder.description = (TextView) convertView.findViewById(R.id.description);
            holder.image = (ImageView) convertView.findViewById(R.id.news_list_item_image);

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

        if (position < getCount()) {
            News newsRow = getItem(position);

            if (newsRow != null) {
                holder.title.setText(newsRow.getTitle().trim().replaceAll("[\n\r]", " "));
                holder.description.setText(newsRow.getDescription().trim().replaceAll("[\n\r]", " "));

                if (newsRow.getPhotoUrl() != null && !newsRow.getPhotoUrl().equalsIgnoreCase("null")) {
                    Ion.with(holder.image).placeholder( R.drawable.icon ).load(newsRow.getPhotoUrl());
                } else {
                    holder.image.setImageResource(R.drawable.icon);
                }
            }
        }
        convertView.setClickable(true);
        convertView.setFocusable(true);
        convertView.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Main.instance.changeNewsFragment(news.get(position).getNewsUrl());
            }
        });

        return convertView;

    } catch (IndexOutOfBoundsException e) {
        progressView = inflater.inflate(R.layout.progress_list_item, null);
        return progressView;
    }
}

@Override
public News getItem(int position) {
    return news.get(position);
}

@Override
public long getItemId(int position) {
    return 0;
}

static class ViewHolder {
    TextView title;
    TextView description;
    ImageView image;
}

public void addNewData(ArrayList<News> newData) {
    if(news == null) {
         news = new ArrayList<News>();
    }
    news.addAll(newData);
    notifyDataSetChanged();
}
}

并替换onPostExecute 

@Override
protected void onPostExecute(NewsArrayList result) {
    mLeftToDownload = result.getLeft();
    ListNewsAdapter adapter = (ListNewsAdapter) listView.getAdapter();
    if (adapter == null) {
        adapter = new ListNewsAdapter(getActivity(), NewsListFragment.this);
        listView.setAdapter(adapter);
    }

    adapter.addNewData(result.getNewsArray());
    isLoading = false;

    super.onPostExecute(result);
}

我希望我不会遗漏任何我刚刚写的东西，我手上没有Eclipse。

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