i want grid view with loading by scroll i have image fetch from sever but i want only 10 images view other can load when scrolling grid view

Question

public class NewMovie extends Activity {
GridView lv;
Vibrator vibrator;
SimpleAdapter adapter;
Button b;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    Log.i("Category", MainActivity.movie_Category);
    setContentView(R.layout.new_movie);

    vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
    lv = (GridView) findViewById(R.id.grid_view);

    // URL to the JSON data
    String strUrl = "http://vaibhavtech.com/work/android/movie_list.php?category="
            + MainActivity.movie_Category + "&sub_category=new";
    // Creating a new non-ui thread task to download json data
    DownloadTask downloadTask = new DownloadTask();
    // Starting the download processt
    downloadTask.execute(strUrl);

    // Getting a reference to ListView of activity_main
    lv.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // // TODO Auto-generated method stub
            vibrator.vibrate(40);
            LayoutInflater inflater = getLayoutInflater();
            View view = inflater.inflate(R.layout.customtoast,
                    (ViewGroup) findViewById(R.id.custom_toast_layout));
            Toast toast = new Toast(getApplicationContext());
            toast.setDuration(Toast.LENGTH_LONG);
            toast.setGravity(Gravity.CENTER_HORIZONTAL, 0, 0);
            toast.setView(view);
            toast.show();
            MainActivity.movie_Id = ((TextView) arg1
                    .findViewById(R.id.tv_girdview_content_id)).getText()
                    .toString();
            Log.i("Name is", MainActivity.movie_Id);

            startActivity(new Intent(NewMovie.this, MovieDescription.class));
        }

    });

}

/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException {
    String data = "";
    InputStream iStream = null;

    try {
        URL url = new URL(strUrl);

        // Creating an http connection to communicate with url
        HttpURLConnection urlConnection = (HttpURLConnection) url
                .openConnection();

        // Connecting to url
        urlConnection.connect();

        // Reading data from url
        iStream = urlConnection.getInputStream();

        BufferedReader br = new BufferedReader(new InputStreamReader(
                iStream));

        StringBuffer sb = new StringBuffer();

        String line = "";
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

        data = sb.toString();

        br.close();

    } catch (Exception e) {
        Log.d("Exception while downloading url", e.toString());
    } finally {
        iStream.close();
    }

    return data;
}

/** AsyncTask to download json data */
private class DownloadTask extends AsyncTask<String, Integer, String> {
    String data = null;

    @Override
    protected String doInBackground(String... url) {
        try {
            data = downloadUrl(url[0]);

        } catch (Exception e) {
            Log.d("Background Task", e.toString());
        }
        return data;
    }

    @Override
    protected void onPostExecute(String result) {

        // The parsing of the xml data is done in a non-ui thread
        ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();

        // Start parsing xml data
        listViewLoaderTask.execute(result);

    }
}

/** AsyncTask to parse json data and load ListView */
private class ListViewLoaderTask extends
        AsyncTask<String, Void, SimpleAdapter> {

    JSONObject jObject;

    // Doing the parsing of xml data in a non-ui thread
    @Override
    protected SimpleAdapter doInBackground(String... strJson) {
        try {
            jObject = new JSONObject(strJson[0]);
            MovieParser countryJsonParser = new MovieParser();
            countryJsonParser.parse(jObject);
        } catch (Exception e) {
            Log.d("JSON Exception1", e.toString());
        }

        // Instantiating json parser class
        MovieParser countryJsonParser = new MovieParser();

        // A list object to store the parsed countries list
        List<HashMap<String, Object>> countries = null;

        try {
            // Getting the parsed data as a List construct
            countries = countryJsonParser.parse(jObject);
        } catch (Exception e) {
            Log.d("Exception", e.toString());
        }

        // Keys used in Hashmap
        String[] from = { "image", "id", "year", "duration", "name" };

        // Ids of views in listview_layout
        // int[] to = {
        // R.id.iv_radio_data_image,R.id.tv_radio_data_id,R.id.tv_radio_data_like,R.id.tv_radio_data_rating,R.id.tv_radio_data_listner,R.id.tv_radio_data_radio_url,R.id.tv_radio_data_name};
        int[] to = { R.id.iv_girdview_content_image,
                R.id.tv_girdview_content_id, R.id.tv_girdview_content_like,
                R.id.tv_girdview_content_listner,
                R.id.tv_girdview_content_name };
        // Instantiating an adapter to store each items
        // R.layout.listview_layout defines the layout of each item
        adapter = new SimpleAdapter(getBaseContext(), countries,
                R.layout.grid_view_content, from, to);

        return adapter;
        // lv.setAdapter(new ListAdapter(getApplicationContext()));
    }

    /** Invoked by the Android on "doInBackground" is executed */
    @Override
    protected void onPostExecute(SimpleAdapter adapter) {

        // Setting adapter for the listview
        lv.setAdapter(adapter);

        for (int i = 0; i < adapter.getCount(); i++) {
            HashMap<String, Object> hm = (HashMap<String, Object>) adapter
                    .getItem(i);
            String imgUrl = (String) hm.get("flag_path");
            ImageLoaderTask imageLoaderTask = new ImageLoaderTask();

            HashMap<String, Object> hmDownload = new HashMap<String, Object>();
            hm.put("flag_path", imgUrl);
            hm.put("position", i);

            // Starting ImageLoaderTask to download and populate image in
            // the listview
            imageLoaderTask.execute(hm);

        }

        // }

    }

    /** AsyncTask to download and load an image in ListView */
    private class ImageLoaderTask
            extends
            AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>> {

        @Override
        protected HashMap<String, Object> doInBackground(
                HashMap<String, Object>... hm) {

            InputStream iStream = null;
            String imgUrl = (String) hm[0].get("flag_path");
            int position = (Integer) hm[0].get("position");

            URL url;
            try {
                url = new URL(imgUrl);

                // Creating an http connection to communicate with url
                HttpURLConnection urlConnection = (HttpURLConnection) url
                        .openConnection();

                // Connecting to url
                urlConnection.connect();

                // Reading data from url
                iStream = urlConnection.getInputStream();

                // Getting Caching directory
                File cacheDirectory = getBaseContext().getCacheDir();

                // Temporary file to store the downloaded image
                File tmpFile = new File(cacheDirectory.getPath() + "/wpta_"
                        + position + ".png");

                // The FileOutputStream to the temporary file
                FileOutputStream fOutStream = new FileOutputStream(tmpFile);

                // Creating a bitmap from the downloaded inputstream
                Bitmap b = BitmapFactory.decodeStream(iStream);

                // Writing the bitmap to the temporary file as png file
                b.compress(Bitmap.CompressFormat.PNG, 100, fOutStream);

                // Flush the FileOutputStream
                fOutStream.flush();

                // Close the FileOutputStream
                fOutStream.close();

                // Create a hashmap object to store image path and its
                // position in the listview
                HashMap<String, Object> hmBitmap = new HashMap<String, Object>();

                // Storing the path to the temporary image file
                hmBitmap.put("image", tmpFile.getPath());

                // Storing the position of the image in the listview
                hmBitmap.put("position", position);

                // Returning the HashMap object containing the image path
                // and position
                return hmBitmap;

            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(HashMap<String, Object> result) {
            // Getting the path to the downloaded image
            String path = (String) result.get("image");

            // Getting the position of the downloaded image
            int position = (Integer) result.get("position");

            // Getting adapter of the listview
            adapter = (SimpleAdapter) lv.getAdapter();

            // Getting the hashmap object at the specified position of the
            // listview
            HashMap<String, Object> hm = (HashMap<String, Object>) adapter
                    .getItem(position);

            // Overwriting the existing path in the adapter
            hm.put("image", path);

            // lv.invalidateViews();
            adapter.notifyDataSetChanged();

        }
    }

}

---------*********************-------------------------------------------

PLZ help i found this ans from loag time i want loading more image from server when scrolling like facebook app style. above my code plz help me.

Answer 1

Benji helped me here.

public class EndlessScrollListener implements OnScrollListener {

    private int visibleThreshold = 5;
    private int currentPage = 0;
    private int previousTotal = 0;
    private boolean loading = true;

    public EndlessScrollListener() {
    }
    public EndlessScrollListener(int visibleThreshold) {
        this.visibleThreshold = visibleThreshold;
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
                currentPage++;
            }
        }
        if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
            // I load the next page of gigs using a background task,
            // but you can call any function here.
            new LoadGigsTask().execute(currentPage + 1);
            loading = true;
        }
    }

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

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