Android：在listview中设置progressbar

我正在尝试在listview中放置一个进度条，以便在从facebook好友列表中获取图片后可以加载它们。我在XML布局中声明进度条。我实现了异步方法。我将图像设置为不可见，并在post-execute方法中将其设置为可见，将进度条设置为消失。但是，进度条仍在视图上旋转，并且不会消失

我的问题与这个问题非常相似，但没有提供解决方案

在自定义阵列适配器中，我的代码如下所示：

更新：

static class ViewHolder {
    public TextView textview;
    public CircularImageView image;
}



@Override
public View getView(int position, View convertView, ViewGroup parent) {


    //REUSES THE VIEW

    if(convertView==null){

        // inflate the layout

        LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();

        convertView = inflater.inflate(layoutResourceId, parent, false);


        // configure view holder
        ViewHolder viewHolder = new ViewHolder();
        viewHolder.textview = (TextView) convertView.findViewById(R.id.textViewItem);
        viewHolder.image = (CircularImageView) convertView.findViewById(R.id.fb_friendpics);
        convertView.setTag(viewHolder);

    }

    // fill data
    ViewHolder holder = (ViewHolder) convertView.getTag();

     ObjectItem objectItem = data[position];

    holder.textview.setText(objectItem.itemName);
    holder.textview.setVisibility(View.INVISIBLE);

    //call the execute cmd
    ProgressBar progressBar = (ProgressBar)convertView.findViewById(R.id.progressbar_fbpics);


    holder.image.setVisibility(View.INVISIBLE);


    new DownloadImageTask(holder, progressBar)
            .execute("https://graph.facebook.com/" + objectItem.itemId + "/picture?type=large");

    return convertView;

}


private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {

    ProgressBar progressBar;
    ViewHolder holder;

    public DownloadImageTask(ViewHolder holder, ProgressBar progressBar) {

        this.holder = holder;
        this.progressBar = progressBar;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        Bitmap mIcon11 = null;
        try {
            InputStream in = new java.net.URL(urldisplay).openStream();
            mIcon11 = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return mIcon11;
    }

    protected void onPostExecute(Bitmap result) {

        if(result!=null ) {
            Log.d("IMAGE: " , "SET");
            progressBar.setVisibility(View.GONE);

            holder.image.setImageBitmap(result);
            holder.image.setVisibility(View.VISIBLE);
            holder.textview.setVisibility(View.VISIBLE);

        }

    }
}

---

根据您的代码，您正在引用一个

progressbar

，它在DownloadTask的外部类中声明为一个字段。您无法直接访问Adapter.getView（）中的

progressbar

除此之外，我还要提出两项建议：

我强烈建议您为此选择第三方映像加载库。例如，看看，和

在适配器中使用视图循环。我可以看出你没有使用任何形式的回收。看看这个

---

谢谢你的帮助。您认为我需要使用NotifyDataSetChanged（）吗？实现视图回收是提高性能的一个好主意。没有提供执行此操作的代码。我是否应该为此使用视图持有者？当您更改基础数据时，应该调用NotifyDataSetChanged。例如，如果添加或删除适配器中的项。但是，当您使用ArrayAdapter.add、ArrayAdapter.remove等时，默认的ArrayAdapter实现将自动为您调用NotifyDataSetChanged，因此无需显式调用它。我只在列表视图上显示Facebook好友列表。因此，数据中的任何内容都不会被删除或添加。因此，我认为我不需要使用NotifyDataSetChanged（）。对于视图回收，您有相关文档吗？只要看看我在回答中发送的2个链接，就可以开始了。@WindsuferOak我更新了上面的代码。我能够使用视图保持器，这提高了列表视图的性能。我将调查毕加索。我想知道你是否能在另一个问题上帮助我

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