CODEWITHSUNDEEP
androidasynchronousandroid-asynctaskadapter
Fahid Nadeem
Fahid Nadeem

Reputation: 412

Getting image from asynctask to custom Gridview Adapter

i am making a gallery app and when i execute my asynctask in Getview of Adapter class then only onPreExecution part of Asynctask gets execute and others don't.

So, what i see is a progress bar But not the image after downloading...on my activity just a progress bar keeps on rolling

Here is my code of Getview method

enter public View getView(int position, View convertview, ViewGroup parent) {
    // TODO Auto-generated method stub
     img=new ImageView(mContext); 
     new DownloadImage().execute();
     return img;

}

and this is my Asynctaskclass

private class DownloadImage extends AsyncTask<String, Void, Bitmap>{
     @Override
        protected void onPreExecute() {
            super.onPreExecute();

            mProgressDialog = new ProgressDialog(mContext);
            // Set progressdialog title
            mProgressDialog.setTitle("Download Image");
            // Set progressdialog message
            mProgressDialog.setMessage("Loading...");
            mProgressDialog.setIndeterminate(false);
            // Show progressdialog
            mProgressDialog.show();
        }
@Override
protected Bitmap doInBackground(String... URL) {
    // TODO Auto-generated method stub
     String imageURL = URL[0];
      Bitmap bitmap = null;
      try {
          // Download Image from URL
          InputStream input = new java.net.URL(imageURL).openStream();
          // Decode Bitmap
          bitmap = BitmapFactory.decodeStream(input);
      } catch (Exception e) {
          e.printStackTrace();
      }
      return bitmap;

}

 @Override
 protected void onPostExecute(Bitmap result) {

     // Set the bitmap into ImageView

     img.setImageBitmap(result);
     // Close progressdialog
     mProgressDialog.dismiss();
 }
}

I think Just right after executing onPreExecution my GetView method return img variable to my MainActivity class..here it is

  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy); 

    setTitle("My Gallery");
    GridView g=(GridView)findViewById(R.id.gallery);
   // Gallery g=(Gallery)findViewById(R.id.gallery);
  //  ImageAdapter width=new ImageAdapter(context);


    g.setAdapter(new ImageAdapter(this));

    Resources r = getResources();
    float padding = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
            GRID_PADDING, r.getDisplayMetrics());





    g.setNumColumns(NUM_OF_COLUMN);
    g.setColumnWidth(columnWidth);
    g.setStretchMode(GridView.NO_STRETCH);
    g.setPadding((int) padding, (int) padding, (int) padding,
            (int) padding);
   // g.setHorizontalSpacing((int) padding);
  //  g.setVerticalSpacing((int) padding);
    g.setOnItemClickListener(new  AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView parent, View v, int position,
                long id) {
            // TODO Auto-generated method stub


            Intent i=new Intent(getApplicationContext(),ImageViewPager.class);
        i.putExtra("id", position);
        startActivity(i);

        }
    });

Can anybody tell me how to proceed?

Upvotes: 0

Views: 973

Answers (1)

codeMagic
codeMagic

Reputation: 44571

You shouldn't be running your AsyncTask in getView(). Since it is asynchronous, getView() won't wait for it to return. It will return a blank ImageView.

You should run the task before setting the adapter and get all of the images first.

You can also use some image loading library like Picaso. You can Google and find other libraries, as well, and how to use them. And you shouldn't be using StrictMode.

To get the images before running getView()

Run the task in onCreate(). Then simply set your Adapter in onPostExecute() of your task.

Related explanation

Upvotes: 2

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