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androidandroid-asynctaskandroid-imageviewpicassouribuilder

How to update my ImageAdapter in post execute method


I have an ImageAdapter class for GridView which is filled by local images.I want to update it by the movie databse api. here is my ImageAdapter class -

package jindal5.mayank.popular_movies_14ce10032_gsc;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {
    private Context mContext;

    public ImageAdapter(Context c) {
        mContext = c;
    }

    public int getCount() {
        return mThumbIds.length;
    }

    public Object getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) {
            // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }

        imageView.setImageResource(mThumbIds[position]);
        return imageView;
    }

    // references to our images
    private Integer[] mThumbIds = {
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7,
            R.drawable.sample_0, R.drawable.sample_1,
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7,
            R.drawable.sample_0, R.drawable.sample_1,
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7
    };
}

This is my MainActivityFragment which contains AscyncTask -

package jindal5.mayank.popular_movies_14ce10032_gsc;

import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridView;
import android.widget.ImageView;

import com.squareup.picasso.Picasso;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment {
    private ImageAdapter imag_adap;

    public MainActivityFragment() {
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Add this line in order for this fragment to handle menu events.
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.menu_fragment, menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_refresh) {
            getimage imageTask = new getimage();
            imageTask.execute("popularity.desc");
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootview = inflater.inflate(R.layout.fragment_main, container, false);
        GridView grid = (GridView) rootview.findViewById(R.id.gridView);
        imag_adap = new ImageAdapter(getActivity());
        grid.setAdapter(imag_adap);
        return rootview;
    }

    public class getimage extends AsyncTask<String, Void, String[]> {
        private final String LOG_TAG = getimage.class.getSimpleName();
        public int count;
        String[] pos_path;


        @Override
        protected String[] doInBackground(String... params) {
            HttpURLConnection urlConnection = null;
            BufferedReader reader = null;
            String movieJsonStr = null;
            try {
                final String movie_url_str = "http://api.themoviedb.org/3/discover/movie?sort_by="+ params[0] +"&api_key=8d7a48043ba1d3348181e2b6615cedc7";
                URL movie_url = new URL(movie_url_str);
                urlConnection = (HttpURLConnection) movie_url.openConnection();
                urlConnection.setRequestMethod("GET");
                urlConnection.connect();
                InputStream inputStream = urlConnection.getInputStream();
                StringBuffer buffer = new StringBuffer();
                if (inputStream == null) {
                    return null;
                }
                reader = new BufferedReader(new InputStreamReader(inputStream));
                String line;
                while ((line = reader.readLine()) != null) {
                    buffer.append(line + "\n");
                }
                if (buffer.length() == 0) {
                    return null;
                }
                movieJsonStr = buffer.toString();
                Log.v(LOG_TAG, "Forecast string: " + movieJsonStr);
                JSONObject movieJson = new JSONObject(movieJsonStr);
                JSONArray movieJsonarray = movieJson.getJSONArray("results");
                 count = movieJsonarray.length();
                pos_path = new String[count];
                for(int i=0;i<count;i++){
                    JSONObject sin_movie = movieJsonarray.getJSONObject(i);
                    pos_path[i] = sin_movie.getString("poster_path");
                }
            } catch (IOException | JSONException e) {
                Log.e(LOG_TAG, "Error ", e);
                return null;
            }
            finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException e) {
                        Log.e(LOG_TAG, "Error closing stream", e);
                    }
                }
            }
            return pos_path;
            }
        @Override
        protected void onPostExecute(String[] result) {
            Uri.Builder url_for_poster = new Uri.Builder();
            ImageView[] im_vi = new ImageView[count];
            for(int j=0;j<count;j++) {
                String pos_sin_path = pos_path[j];
               Uri.Builder url_build =  url_for_poster.scheme("http").authority("image.tmdb.org/t/p").appendPath("w92").appendPath("pos_sin_path");
                String url = url_build.toString();
                Picasso.with(getActivity()).load("http://image.tmdb.org/t/p/w185//nBNZadXqJSdt05SHLqgT0HuC5Gm.jpg").into(im_vi[j]);  **probably this shows target must be null**
                //imag_adap.getItem(j) = im_vi[j];  **after uncommenting it shows variable expexted**
            }
        }
    }
}

Solution

  • Change adapter like as follows,

    public class ImageAdapter extends BaseAdapter {
        private String drawablePrefix;
        private Context mContext;
        private ArrayList<String> mThumbUris;
    
        public ImageAdapter(Context c) {
            mContext = c;
            String packName=mContext.getPackageName();
            drawablePrefix="android.resource://" +packName+ "/";
    
            ArrayList<String> uriPaths=new ArrayList<>();// place your drawables.
    
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            uriPaths.add(drawablePrefix+ R.drawable.wall_bird);
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            uriPaths.add(drawablePrefix+ R.drawable.weather);
            mThumbUris=uriPaths;
        }
    
        public int getCount() {
            return mThumbUris.size();
        }
    
        public String getItem(int position) {
            return mThumbUris.get(position);
        }
    
        public long getItemId(int position) {
            return 0;
        }
    
        // create a new ImageView for each item referenced by the Adapter
        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView imageView;
            if (convertView == null) {
                // if it's not recycled, initialize some attributes
                imageView = new ImageView(mContext);
                imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
                imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
                imageView.setPadding(8, 8, 8, 8);
            } else {
                imageView = (ImageView) convertView;
            }
    
            Uri imgUri=Uri.parse(mThumbUris.get(position));
    
            Picasso.with(mContext)
                    .load(imgUri)
                    .placeholder(R.drawable.weather)
                    .centerCrop()
                    .resize(400, 400)
                    .into(imageView);
    
            return imageView;
        }
    
        public ArrayList<String> getUriList(){
            return mThumbUris;
        }
    }
    

    change onPostExecute logic as follows.

     protected void onPostExecute(String[] result) {
                Uri.Builder url_for_poster = new Uri.Builder();
                ArrayList<String> uriPaths = imag_adap.getUriList();
                uriPaths.clear();
                for (int j = 0; j < count; j++) {
                    String pos_sin_path = pos_path[j];
                    Uri.Builder url_build = url_for_poster.scheme("http").authority("image.tmdb.org/t/p").appendPath("w92").appendPath("pos_sin_path");
                    String url = url_build.toString();
                    uriPaths.add(url);
                }
                imag_adap.notifyDataSetChanged();
            }
    

    then it works fine.