Question

我正在开展一个项目。在我的项目中，当用户单击列表项时，它会从某个源下载文件并将其保存到内部存储中。

如果文件已经下载，我想在listview的列表项中显示图像。

下面的代码工作正常，但它也显示了尚未下载文件的列表项的图像。

这是我的adapter class代码。

package life.quran.com.quranlife;

public class SurahBaseSearchAdapter extends BaseAdapter {

    Context mContext;
    LayoutInflater mInflator;
    private List<Surah> surahList = null;
    private ArrayList<Surah> arrayList;
    Surah surah;
    ArrayList<String> imgfileLocation = null;

    String searchhighlightString = "";

    public SurahBaseSearchAdapter(Context context, List<Surah> list) {

        mContext = context;
        surahList = list;
        mInflator = LayoutInflater.from(context);
        arrayList = new ArrayList<Surah>();
        arrayList.addAll(surahList);

    }

    public class ViewHolder {
        TextView sname;
        TextView sno;
        ImageView dlimg;
    }

    @Override
    public int getCount() {
        return surahList.size();
    }

    @Override
    public Object getItem(int position) {
        return surahList.get(position);
    }

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

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

        imgfileLocation = new ArrayList<>();
        surah = surahList.get(position);
        File f = mContext.getFilesDir();
        String filepath =  f.getAbsolutePath();
        File _file = new File(filepath+"/surah_"+surah.getSurah_id()+".json");



        final ViewHolder holder;
        if (convertView == null) {
            holder = new ViewHolder();
            convertView = mInflator.inflate(R.layout.item_template,null);
            holder.sname = (TextView) convertView.findViewById(R.id.txt_surahName);
            holder.sno = (TextView) convertView.findViewById(R.id.txtsuraNo);
            holder.dlimg = convertView.findViewById(R.id.dlimg);


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

        holder.sname.setText(surah.getSurah_name());
        holder.sno.setText(surah.getSurah_no());

        if (_file.exists()) {

            holder.dlimg.setImageResource(R.drawable.newdlimg);
        }


        String hSurahName = surah.getSurah_name().toLowerCase(Locale.getDefault());
        if(hSurahName.contains(searchhighlightString)) {
            int startpos = hSurahName.indexOf(searchhighlightString);
            int endpos = startpos + searchhighlightString.length();

            Spannable spanText = Spannable.Factory.getInstance().newSpannable(holder.sname.getText());
            spanText.setSpan(new ForegroundColorSpan(Color.BLUE),startpos,endpos,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

            holder.sname.setText(spanText,TextView.BufferType.SPANNABLE);
        }



        return convertView;
    }

    public void filter(String charText) {

        searchhighlightString = charText;


        charText = charText.toLowerCase(Locale.getDefault());
        surahList.clear();
        if(charText.length() == 0) {
            surahList.addAll(arrayList);
        } else {
            for(Surah surah : arrayList) {
                if(surah.getSurah_name().toLowerCase(Locale.getDefault()).contains(charText)) {
                    surahList.add(surah);
                }
            }
        }
        notifyDataSetChanged();
    }
}

如果有什么不清楚，请告诉我

Answer 1

如果文件不存在，则需要设置默认drawable。如果条件如

，则将其他部分添加到此处

if (_file.exists()) {
    holder.dlimg.setImageResource(R.drawable.newdlimg);
}else{
    holder.dlimg.setImageResource(R.drawable.<default_image>);
}

Answer 2

您应该在上次使用后清除ViewHolder中的图像。只需将您的代码更改为以下内容：

if (_file.exists()) {

    holder.dlimg.setImageResource(R.drawable.newdlimg);
} else {
    //clear image from previous usage
    //do not sure is it legal to set null. You need to check it.
    holder.dlimg.setImageResource(null)
}

如果文件特定文件已下载内部存储

2 个答案: