图像缩略图未正确设置 [英] Image thumbnails not setting correctly

问题描述

我正在尝试创建一个文件浏览器。除了我的图像缩略图加载太慢外，我实现了所有目标。所以我读到我必须转到asynctask然后在post执行更新ui。在运行asynctask之前，我为所有文件提供了一个默认缩略图。在asynctask中我将position作为参数，因为我使用它们设置了标签。然后我使用该位置检查文件。如果那个图像或视频我为它创建了一个位图。在post post中，我创建了一个新的viewholder，并使用getTag（position）为它分配相同的标签。然后我使用setBitmapImage分配位图。问题：即使对于非图像/视频的文件，缩略图也在变化/闪烁。
到目前为止我尝试过的事情：
a）使用AsyncTask为Android ListView更新图像缩略图不正确

b） Android ListView使用AsyncTask更新图像缩略图导致视图回收

<这是我的getView代码：

  @Override 
 public View getView（final int position，View convertView， ViewGroup parent）{
 
 
文件file = new File（String.valueOf（filenames [position]））; 
 if（file.isDirectory（））{
 img = R.drawable.folder; 
} 
 
 else {
 img = getImage（filenames [position]）; 
} 
 
 ViewHolder viewHolder = null; 
 if（convertView == null）{
 LayoutInflater inflator = LayoutInflater.from（getContext（））; 
 convertView = inflator.inflate（R.layout.list_item，null）; 
 viewHolder = new ViewHolder（）; 
 viewHolder.tv =（TextView）convertView.findViewById（R.id.textView1）; 
 viewHolder.cb =（CheckBox）convertView.findViewById（R.id.checkBox1）; 
 viewHolder.iv =（ImageView）convertView.findViewById（R.id.imageView）; 
 viewHolder.cb.setOnCheckedChangeListener（new CompoundButton.OnCheckedChangeListener（）{
 
 @Override 
 public void onCheckedChanged（CompoundButton buttonView，boolean isChecked）{
 int getPosition =（整数）buttonView.getTag（）; //这里我们使用setTag得到我们为复选框设置的位置。
 myList.get（getPosition）.setSelected（buttonView.isChecked（））; //设置值复选框以保持其状态。
} 
}）; 
 convertView.setTag（viewHolder）; 
 convertView.setTag（R.id.textView1，viewHolder.tv）; 
 convertView.setTag（R.id.checkBox1，viewHolder.cb）; 
 convertView.setTag（R.id.checkBox1，viewHolder.iv）; 
} 
 else {
 viewHolder =（ViewHolder）convertView.getTag（）; 
} 
 viewHolder.iv.getLayoutParams（）。height = 80; 
 viewHolder.iv.getLayoutParams（）。width = 80; 
 viewHolder.cb.setTag（position）; 
 final ViewHolder ViewHolder = viewHolder; 
 ViewHolder.iv.setImageResource（img）; 
 ViewHolder.tv.setText（myList.get（position）.getName（））; 
 ViewHolder.cb.setChecked（myList.get（position）.isSelected（））; 
 
 
 final查看finalConvertView = convertView; 
 class myTask扩展AsyncTask< Integer，Void，Bitmap> {
 
 int pos; 
 public myTask（int pos）{
 this.pos = pos; 
} 
 
 @Override 
 protected Bitmap doInBackground（Integer ... params）{
 Bitmap thumb = null; 
 
 if（（String.valueOf（filenames [pos]））。contains（。jpeg）|| String.valueOf（filenames [pos]）。contains（。jpg）||将String.valueOf（文件名[POS]）。包含（ PNG ）||将String.valueOf（文件名[POS]）。包含（。BMP）||将String.valueOf（文件名[POS]）。包含（ .webp）|| String.valueOf（filenames [pos]）。contains（。gif））{
 thumb = ThumbnailUtils.extractThumbnail（BitmapFactory.decodeFile（String.valueOf（filenames [pos]）） ，64,64）; 
 
} 
 else if（（String.valueOf（filenames [pos]））。contains（。mp4）|| String.valueOf（filenames [pos]）。contains（ .MKV ）||将String.valueOf（文件名[POS]）。包含（。WEBM ）||将String.valueOf（文件名[POS]）。包含（。3GP）||将String.valueOf（文件名[ pos]）。contains（。3gpp））{
 thumb = ThumbnailUtils.createVideoThumbnail（filenames [pos] .getPath（），MediaStore.Video.Thumbnails.MINI_KIND）; 
 
} 
返回拇指; 
} 
 @Override 
 protected void onPostExecute（Bitmap thumb）{
 if（isCancelled（））{
 return; 
} 
 ViewHolder v =（ViewHolder）finalConvertView.getTag（pos）; 
 
 if（（String.valueOf（filenames [pos]））。contains（。jpeg）|| String.valueOf（filenames [pos]）。contains（。jpg）||将String.valueOf（文件名[POS]）。包含（ PNG ）||将String.valueOf（文件名[POS]）。包含（。BMP）||将String.valueOf（文件名[POS]）。包含（ .webp）|| String.valueOf（filenames [pos]）。contains（。gif））{
 
 v.iv.setImageBitmap（thumb）; 
} 
 else if（（String.valueOf（filenames [pos]））。contains（。mp4）|| String.valueOf（filenames [pos]）。contains（。mkv） ||将String.valueOf（文件名[POS]）。包含（ WEBM ）||将String.valueOf（文件名[POS]）。包含（。3GP）||将String.valueOf（文件名[POS]）。 contains（。3gpp））{
 
 v.iv.setImageBitmap（thumb）; 
} 
 
 
} 
} 
 
 myTask m = new myTask（position）; 
 m.execute（）; 
 
 return convertView; 
 
 
 
} 
  

解决方案

我终于找到了答案。

这是ListAdapter类：

  class ListAdapter extends ArrayAdapter<模态> {
 
私人最终上下文背景; 
 private int img; 
 
 private List< Modal>我的列表; 
 private文件名[]; 
 private List< Integer> selectedItems = new ArrayList< Integer>（）; 
 private CheckBox cb; 
 public ListAdapter（Context context，List< Modal> list，File filenames []）{
 super（context，R.layout.list_item，list）; 
 this.context = context; 
 this.myList = list; 
 this.filenames = filenames; 
} 
 
 
 @Override 
 public int getViewTypeCount（）{
 
 if（getCount（）> 0）{
 return getCount（）; 
} 
返回1; 
} 
 
 @Override 
 public int getItemViewType（int position）{
 
返回位置; 
} 
 
 @Override 
 public long getItemId（int position）{
 return position; 
} 
 
 
静态类ViewHolder {
 TextView tv; 
 CheckBox cb; 
静态ImageView iv; 
} 
 
 public int getImage（File filename）{
 if（String.valueOf（filename）.contains（。rar）|| String.valueOf（filename）。 contains（。zip））{
 return R.drawable.archive; 
} 
 else if（String.valueOf（filename）.contains（。doc）|| String.valueOf（filename）.contains（。docx））{
 return R .drawable.doc; 
} 
 else if（String.valueOf（filename）.contains（。pdf））{
 return R.drawable.pdf; 
} 
 else if（String.valueOf（filename）.contains（。txt））{
 return R.drawable.txt; 
} 
 else if（String.valueOf（filename）.contains（。ppt）|| String.valueOf（filename）.contains（。pptx））{
 return R .drawable.ppt; 
} 
 else if（String.valueOf（filename）.contains（。xls）|| String.valueOf（filename）.contains（。xlsx））{
 return R .drawable.xls; 
} 
 else if（（String.valueOf（filename）.contains（。jpeg）|| String.valueOf（filename）.contains（。jpg）|| String.valueOf（filename ）。载（ PNG ）||将String.valueOf（文件名）。载（。BMP ）||将String.valueOf（文件名）。载（。WEBP）||将String.valueOf（文件名）。 contains（。gif）））{
 return R.drawable.image; 
} 
 else if（（String.valueOf（filename）.contains（。mp4）|| String.valueOf（filename）.contains（。mkv）|| String.valueOf（filename ）。载（ WEBM ）||将String.valueOf（文件名）。载（。3GP ）||将String.valueOf（文件名）。载（。3GPP））||将String.valueOf（文件名） .contains（。MOV））{
 return R.drawable.video; 
} 
 else if（（String.valueOf（filename）.contains（。mp3）|| String.valueOf（filename）.contains（。wav）|| String.valueOf（filename ）。载（ WMA ）||将String.valueOf（文件名）。载（。MP2 ）||将String.valueOf（文件名）。载（。AAC）||将String.valueOf（文件名）。包含（ AC3 ）||将String.valueOf（文件名）。载有（ AU ）||将String.valueOf（文件名）。载有（ OGG）||将String.valueOf（文件名）。载有（ 。FLAC）））{
返回R.drawable.music; 
} 
 
 else {
返回R.drawable.unknown; 
} 
 
} 
 
 
 @Override 
 public View getView（final int position，View convertView，ViewGroup parent）{
 
 
 
 
文件file = new File（String.valueOf（filenames [position]））; 
 if（file.isDirectory（））{
 img = R.drawable.folder; 
} 
 
 else {
 img = getImage（filenames [position]）; 
} 
 
 
 ViewHolder viewHolder = null; 
 
 if（convertView == null）{
 LayoutInflater inflator = LayoutInflater.from（getContext（））; 
 convertView = inflator.inflate（R.layout.list_item，null）; 
 viewHolder = new ViewHolder（）; 
 viewHolder.tv =（TextView）convertView.findViewById（R.id.textView1）; 
 viewHolder.cb =（CheckBox）convertView.findViewById（R.id.checkBox1）; 
 viewHolder.iv =（ImageView）convertView.findViewById（imageView）; 
 viewHolder.cb.setOnCheckedChangeListener（new CompoundButton.OnCheckedChangeListener（）{
 
 @Override 
 public void onCheckedChanged（CompoundButton buttonView，boolean isChecked）{
 int getPosition =（整数）buttonView.getTag（）; //这里我们使用setTag得到我们为复选框设置的位置。
 myList.get（getPosition）.setSelected（buttonView.isChecked（））; //设置值复选框以保持其状态。
} 
}）; 
 convertView.setTag（viewHolder）; 
 convertView.setTag（R.id.textView1，viewHolder.tv）; 
 convertView.setTag（R.id.checkBox1，viewHolder.cb）; 
 convertView.setTag（R.id.checkBox1，viewHolder.iv）; 
} 
 else {
 viewHolder =（ViewHolder）convertView.getTag（）; 
} 
 
 viewHolder.iv.getLayoutParams（）。height = 150; 
 viewHolder.iv.getLayoutParams（）。width = 150; 
 viewHolder.cb.setTag（position）; 
 final ViewHolder ViewHolder = viewHolder; 
 
 ViewHolder.tv.setText（myList.get（position）.getName（））; 
 ViewHolder.cb.setChecked（myList.get（position）.isSelected（））; 
 viewHolder.iv.setImageResource（img）; 
 
 
 Log.v（this，viewHolderMT：+ String.valueOf（viewHolder）+position：+ position）; 
 myTask m = new myTask（position，viewHolder.iv）; 
 m.execute（）; 
 
 return convertView; 
 
 
 
} 
 class myTask扩展AsyncTask<整数，位图，位图> {
 
 
 
 int POS机; 
 ImageView iv; 
 public myTask（int pos，ImageView iv）{
 this.pos = pos; 
 this.iv = iv; 
 iv.setTag（pos）; 
 
 
} 
 
 @Override 
 protected Bitmap doInBackground（Integer ... params）{
 Bitmap thumb = null; 
 
 
 if（（String.valueOf（filenames [pos]））。contains（。jpeg）|| String.valueOf（filenames [pos]）。contains（。jpg ）||将String.valueOf（文件名[POS]）。包含（。PNG ）||将String.valueOf（文件名[POS]）。包含（。BMP）||将String.valueOf（文件名[POS] ）.contains（。webp）|| String.valueOf（filenames [pos]）。contains（。gif））{
 
 thumb = ThumbnailUtils.extractThumbnail（BitmapFactory.decodeFile（String。 valueOf（filenames [pos]）），150,150）; 
 
} 
 else if（（String.valueOf（filenames [pos]））。contains（。mp4）|| String.valueOf（filenames [pos]）。contains（ .MKV ）||将String.valueOf（文件名[POS]）。包含（。WEBM ）||将String.valueOf（文件名[POS]）。包含（。3GP）||将String.valueOf（文件名[ pos]）。contains（。3gpp）|| String.valueOf（filenames [pos]）。contains（。MOV））{
 thumb = ThumbnailUtils.createVideoThumbnail（filenames [pos] .getPath（） ，MediaStore.Video.Thumbnails.MINI_KIND）; 
 
 
} 
返回拇指; 
} 
 @Override 
 protected void onProgressUpdate（Bitmap ... thumb）{
 
 
} 
 @Override 
 protected void onPostExecute（Bitmap thumb）{
 
 
 if（thumb！= null&&（Integer）iv.getTag（）== this.pos）{
 if（
 if） （String.valueOf（filenames [pos]））。contains（。jpeg）|| String.valueOf（filenames [pos]）。contains（。jpg）|| String.valueOf（filenames [pos]）。 contains（。png）|| String.valueOf（filenames [pos]）。contains（。bmp）|| String.valueOf（filenames [pos]）。contains（。webp）|| String.valueOf （filenames [pos]）。contains（。gif））{
 
 iv.setImageBitmap（thumb）; 
 
} 
 else if（（String.valueOf（filenames [pos]））。contains（。mp4）|| String.valueOf（filenames [pos]）。contains（ .MOV）|| String.valueOf（filenames [pos]）。contains（。mkv）|| String.valueOf（filenames [pos]）。contains（。webm）|| String.valueOf（filenames [ pos]）。contains（。3gp）|| String.valueOf（filenames [pos]）。contains（。3gpp））{
 
 iv.setImageBitmap（thumb）; 
} 
 
 
} 
 
 
 
 
 
} 
} 
} 
  

我犯的错误：

• 在getview（）之外移动AsyncTask


• 在异步构造函数中提供对imageView的引用


• 同时实现getItemViewType（）和getItemId（）函数


• 没有检查onPostExecute中的位置标记，因此图像在洗牌。

这需要一段时间让我弄明白。希望它能帮助别人！

I am trying to make a file explorer. I achieved it all except that my image thumbnails were loading too slow. So I read that I must move to asynctask and then in post execute update the ui. Before running asynctask I provide a default thumbnail to all my files. In asynctask I take position as parameter because I set tags using them. Then I check the file using that position. If thats image or video I create a bitmap for it. In post execute I create a new viewholder and assign it the same tag using getTag(position). Then I assign the bitmap using setBitmapImage. Problem: Thumbnails are changing/blinking even for the files that are not images/videos. Things I have tried so far: a)updating of Image Thumbnails using AsyncTask for Android ListView not coming proper
b)Android ListView updating of Image Thumbnails using AsyncTask Causes View recycling

here is my code for getView:

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


    File file=new File(String.valueOf(filenames[position]));
    if(file.isDirectory()){
        img=R.drawable.folder;
    }

    else{
        img=getImage(filenames[position]);
    }

    ViewHolder viewHolder = null;
    if (convertView == null) {
        LayoutInflater inflator = LayoutInflater.from(getContext());
        convertView = inflator.inflate(R.layout.list_item, null);
        viewHolder = new ViewHolder();
        viewHolder.tv = (TextView) convertView.findViewById(R.id.textView1);
        viewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox1);
        viewHolder.iv= (ImageView)convertView.findViewById(R.id.imageView);
        viewHolder.cb.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                int getPosition = (Integer) buttonView.getTag();  // Here we get the position that we have set for the checkbox using setTag.
                myList.get(getPosition).setSelected(buttonView.isChecked()); // Set the value of checkbox to maintain its state.
            }
        });
        convertView.setTag(viewHolder);
        convertView.setTag(R.id.textView1, viewHolder.tv);
        convertView.setTag(R.id.checkBox1, viewHolder.cb);
        convertView.setTag(R.id.checkBox1, viewHolder.iv);
    }
    else {
        viewHolder = (ViewHolder) convertView.getTag();
    }
    viewHolder.iv.getLayoutParams().height = 80;
    viewHolder.iv.getLayoutParams().width = 80;
    viewHolder.cb.setTag(position);
    final ViewHolder ViewHolder= viewHolder;
    ViewHolder.iv.setImageResource(img);
    ViewHolder.tv.setText(myList.get(position).getName());
    ViewHolder.cb.setChecked(myList.get(position).isSelected());


    final View finalConvertView = convertView;
    class myTask extends AsyncTask<Integer,Void,Bitmap>{

        int pos;
        public myTask(int pos){
            this.pos=pos;
        }

        @Override
        protected Bitmap doInBackground(Integer... params) {
            Bitmap thumb=null;

            if((String.valueOf(filenames[pos])).contains(".jpeg")||String.valueOf(filenames[pos]).contains(".jpg")||String.valueOf(filenames[pos]).contains(".png")||String.valueOf(filenames[pos]).contains(".bmp")||String.valueOf(filenames[pos]).contains(".webp")||String.valueOf(filenames[pos]).contains(".gif")){
                thumb = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(String.valueOf(filenames[pos])), 64, 64);

            }
            else if((String.valueOf(filenames[pos])).contains(".mp4")||String.valueOf(filenames[pos]).contains(".mkv")||String.valueOf(filenames[pos]).contains(".webm")||String.valueOf(filenames[pos]).contains(".3gp")||String.valueOf(filenames[pos]).contains(".3gpp")){
                thumb=ThumbnailUtils.createVideoThumbnail(filenames[pos].getPath(), MediaStore.Video.Thumbnails.MINI_KIND);

            }
            return thumb;
        }
        @Override
        protected void onPostExecute(Bitmap thumb){
            if(isCancelled()){
                return;
            }
            ViewHolder v= (ViewHolder) finalConvertView.getTag(pos);

            if((String.valueOf(filenames[pos])).contains(".jpeg")||String.valueOf(filenames[pos]).contains(".jpg")||String.valueOf(filenames[pos]).contains(".png")||String.valueOf(filenames[pos]).contains(".bmp")||String.valueOf(filenames[pos]).contains(".webp")||String.valueOf(filenames[pos]).contains(".gif")){

                v.iv.setImageBitmap(thumb);
            }
            else if((String.valueOf(filenames[pos])).contains(".mp4")||String.valueOf(filenames[pos]).contains(".mkv")||String.valueOf(filenames[pos]).contains(".webm")||String.valueOf(filenames[pos]).contains(".3gp")||String.valueOf(filenames[pos]).contains(".3gpp")){

                v.iv.setImageBitmap(thumb);
            }


        }
    }

    myTask m=new myTask(position);
    m.execute();

   return convertView;



}

解决方案

I have finally found answer to this.

Here is the ListAdapter Class:

class ListAdapter extends ArrayAdapter<Modal> {

    private final Context context;
    private int img;

    private List<Modal> myList;
    private File filenames[];
    private List<Integer> selectedItems=new ArrayList<Integer>();
    private CheckBox cb;
    public ListAdapter(Context context, List<Modal> list, File filenames[]) {
        super(context, R.layout.list_item, list);
        this.context = context;
        this.myList = list;
        this.filenames=filenames;
    }


    @Override
    public int getViewTypeCount() {

        if(getCount()>0){
            return getCount();
        }
        return 1;
    }

    @Override
    public int getItemViewType(int position) {

        return position;
    }

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


    static class ViewHolder {
        TextView tv;
        CheckBox cb;
        static ImageView iv;
    }

    public int getImage(File filename){
        if(String.valueOf(filename).contains(".rar")||String.valueOf(filename).contains(".zip")){
            return R.drawable.archive;
        }
        else if(String.valueOf(filename).contains(".doc")||String.valueOf(filename).contains(".docx")){
            return  R.drawable.doc;
        }
        else if(String.valueOf(filename).contains(".pdf")){
            return R.drawable.pdf;
        }
        else if(String.valueOf(filename).contains(".txt")){
            return R.drawable.txt;
        }
        else if(String.valueOf(filename).contains(".ppt")||String.valueOf(filename).contains(".pptx")){
            return R.drawable.ppt;
        }
        else if(String.valueOf(filename).contains(".xls")||String.valueOf(filename).contains(".xlsx")){
            return R.drawable.xls;
        }
        else if((String.valueOf(filename).contains(".jpeg")||String.valueOf(filename).contains(".jpg")||String.valueOf(filename).contains(".png")||String.valueOf(filename).contains(".bmp")||String.valueOf(filename).contains(".webp")||String.valueOf(filename).contains(".gif"))){
            return R.drawable.image;
        }
        else if((String.valueOf(filename).contains(".mp4")||String.valueOf(filename).contains(".mkv")||String.valueOf(filename).contains(".webm")||String.valueOf(filename).contains(".3gp")||String.valueOf(filename).contains(".3gpp"))||String.valueOf(filename).contains(".MOV")){
            return R.drawable.video;
        }
        else if((String.valueOf(filename).contains(".mp3")||String.valueOf(filename).contains(".wav")||String.valueOf(filename).contains(".wma")||String.valueOf(filename).contains(".MP2")||String.valueOf(filename).contains(".AAC")||String.valueOf(filename).contains(".AC3")||String.valueOf(filename).contains(".AU")||String.valueOf(filename).contains(".OGG")||String.valueOf(filename).contains(".FLAC"))){
            return R.drawable.music;
        }

        else {
            return R.drawable.unknown;
        }

    }


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




        File file=new File(String.valueOf(filenames[position]));
        if(file.isDirectory()){
            img=R.drawable.folder;
        }

        else{
            img=getImage(filenames[position]);
        }


        ViewHolder viewHolder = null;

        if (convertView == null) {
            LayoutInflater inflator = LayoutInflater.from(getContext());
            convertView = inflator.inflate(R.layout.list_item, null);
            viewHolder = new ViewHolder();
            viewHolder.tv = (TextView) convertView.findViewById(R.id.textView1);
            viewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox1);
            viewHolder.iv= (ImageView)convertView.findViewById(imageView);
            viewHolder.cb.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    int getPosition = (Integer) buttonView.getTag();  // Here we get the position that we have set for the checkbox using setTag.
                    myList.get(getPosition).setSelected(buttonView.isChecked()); // Set the value of checkbox to maintain its state.
                }
            });
            convertView.setTag(viewHolder);
            convertView.setTag(R.id.textView1, viewHolder.tv);
            convertView.setTag(R.id.checkBox1, viewHolder.cb);
            convertView.setTag(R.id.checkBox1, viewHolder.iv);
        }
        else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.iv.getLayoutParams().height = 150;
        viewHolder.iv.getLayoutParams().width = 150;
        viewHolder.cb.setTag(position);
        final ViewHolder ViewHolder= viewHolder;

        ViewHolder.tv.setText(myList.get(position).getName());
        ViewHolder.cb.setChecked(myList.get(position).isSelected());
        viewHolder.iv.setImageResource(img);


        Log.v("this","viewHolderMT: "+String.valueOf(viewHolder)+" position: "+position);
        myTask m=new myTask(position,viewHolder.iv);
        m.execute();

       return convertView;



    }
    class myTask extends AsyncTask<Integer,Bitmap,Bitmap>{



        int pos;
        ImageView iv;
        public myTask(int pos,ImageView iv){
            this.pos=pos;
            this.iv=iv;
            iv.setTag(pos);


        }

        @Override
        protected Bitmap doInBackground(Integer... params) {
            Bitmap thumb=null;


            if((String.valueOf(filenames[pos])).contains(".jpeg")||String.valueOf(filenames[pos]).contains(".jpg")||String.valueOf(filenames[pos]).contains(".png")||String.valueOf(filenames[pos]).contains(".bmp")||String.valueOf(filenames[pos]).contains(".webp")||String.valueOf(filenames[pos]).contains(".gif")){

                thumb = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(String.valueOf(filenames[pos])), 150, 150);

            }
            else if((String.valueOf(filenames[pos])).contains(".mp4")||String.valueOf(filenames[pos]).contains(".mkv")||String.valueOf(filenames[pos]).contains(".webm")||String.valueOf(filenames[pos]).contains(".3gp")||String.valueOf(filenames[pos]).contains(".3gpp")||String.valueOf(filenames[pos]).contains(".MOV")){
                thumb=ThumbnailUtils.createVideoThumbnail(filenames[pos].getPath(), MediaStore.Video.Thumbnails.MINI_KIND);


            }
            return thumb;
        }
        @Override
        protected void onProgressUpdate(Bitmap... thumb){


        }
        @Override
        protected void onPostExecute(Bitmap thumb){


            if(thumb!=null && (Integer)iv.getTag()==this.pos) {
                if ((String.valueOf(filenames[pos])).contains(".jpeg") || String.valueOf(filenames[pos]).contains(".jpg") || String.valueOf(filenames[pos]).contains(".png") || String.valueOf(filenames[pos]).contains(".bmp") || String.valueOf(filenames[pos]).contains(".webp") || String.valueOf(filenames[pos]).contains(".gif")) {

                    iv.setImageBitmap(thumb);

                }
                 else if ((String.valueOf(filenames[pos])).contains(".mp4") ||String.valueOf(filenames[pos]).contains(".MOV")|| String.valueOf(filenames[pos]).contains(".mkv") || String.valueOf(filenames[pos]).contains(".webm") || String.valueOf(filenames[pos]).contains(".3gp") || String.valueOf(filenames[pos]).contains(".3gpp")) {

                    iv.setImageBitmap(thumb);
                }


            }





        }
    }
}

Mistakes I was making:

• Move AsyncTask outside getview()
• Give a reference to the imageView inside the async constructor
• Also Implement the getItemViewType() and getItemId() functions
• Was not checking the position tag in onPostExecute so the images were shuffling.

This took a while for me to figure out. Hope it helps others!

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