Android: display image in image view using SimpleAdapter

Question

I am a new android, now I want to display an image from a URL. I am using viewview in listview. I want to add a list of images to each line of a list item. I used the SimpleAdapter, but the image is not displayed.

Here is the main activity:

package com.example.mysqltest;

    import java.util.ArrayList;
    import java.util.HashMap;
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;
    import android.app.ListActivity;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.AdapterView.OnItemClickListener;
    import android.widget.ListAdapter;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;

    public class ReadComments extends ListActivity {

        // Progress Dialog
        private ProgressDialog pDialog;

        // testing on Emulator:
        private static final String READ_COMMENTS_URL = "http://192.168.30.198/test/webservice/comments.php";


        // JSON IDS:
        private static final String TAG_SUCCESS = "success";
        private static final String TAG_TITLE = "title";
        private static final String TAG_POSTS = "posts";
        private static final String TAG_POST_ID = "post_id";
        private static final String TAG_USERNAME = "username";
        private static final String TAG_MESSAGE = "message";
        private static final String TAG_IMAGE = "image";


        // An array of all of our comments
        private JSONArray mComments = null;
        // manages all of our comments in a list.
        private ArrayList<HashMap<String, String>> mCommentList;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            // note that use read_comments.xml instead of our single_post.xml
            setContentView(R.layout.read_comments);
        }

        @Override
        protected void onResume() {
            // TODO Auto-generated method stub
            super.onResume();
            // loading the comments via AsyncTask
            new LoadComments().execute();
        }

        public void addComment(View v) {
            Intent i = new Intent(ReadComments.this, AddComment.class);
            startActivity(i);
        }

        /**
         * Retrieves recent post data from the server.
         */
        public void updateJSONdata() {
            mCommentList = new ArrayList<HashMap<String, String>>();

            JSONParser jParser = new JSONParser();      
            JSONObject json = jParser.getJSONFromUrl(READ_COMMENTS_URL);

            try {
                mComments = json.getJSONArray(TAG_POSTS);

                for (int i = 0; i < mComments.length(); i++) {
                    JSONObject c = mComments.getJSONObject(i);

                    // gets the content of each tag
                    String title = c.getString(TAG_TITLE);
                    String content = c.getString(TAG_MESSAGE);
                    String username = c.getString(TAG_USERNAME);
                    String image = c.getString(TAG_IMAGE);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    map.put(TAG_TITLE, title);
                    map.put(TAG_MESSAGE, content);
                    map.put(TAG_USERNAME, username);
                    map.put(TAG_IMAGE, image);

                    // adding HashList to ArrayList
                    mCommentList.add(map);
                }

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

        /**
         * Inserts the parsed data into the listview.
         */
        private void updateList() { 
            ListAdapter adapter = new SimpleAdapter(this, mCommentList,
                    R.layout.single_post, new String[] { TAG_TITLE, TAG_MESSAGE,
                            TAG_USERNAME,TAG_IMAGE }, new int[] { R.id.title, R.id.message,
                            R.id.username, R.id.imageView1 });

            // I shouldn't have to comment on this one:
            setListAdapter(adapter);    

            ListView lv = getListView();    
            lv.setOnItemClickListener(new OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view,
                        int position, long id) {}
            });
        }

        public class LoadComments extends AsyncTask<Void, Void, Boolean> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(ReadComments.this);
                pDialog.setMessage("Loading Comments...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            @Override
            protected Boolean doInBackground(Void... arg0) {
                updateJSONdata();
                return null;

            }

            @Override
            protected void onPostExecute(Boolean result) {
                super.onPostExecute(result);
                pDialog.dismiss();
                updateList();
            }
        }
    }

Answer 1

Good. Therefore, I assume that you insist on using SimpleAdapter. No problem, problem resolved, just follow these steps:

row.xml ListView, ImageView. ( , , , ImageView)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="5dp"
        android:layout_marginTop="5dp"
        android:src="@drawable/ic_launcher" />


</RelativeLayout>

SimpleAdapter

package com.example.helpstack;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.SimpleAdapter;

public class MySimpleAdapter extends SimpleAdapter {
    private Context mContext;
    public LayoutInflater inflater = null;

    public MySimpleAdapter(Context context,
            List<? extends Map<String, ?>> data, int resource, String[] from,
            int[] to) {
        super(context, data, resource, from, to);
        mContext = context;
        inflater = (LayoutInflater) mContext
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View vi = convertView;
        if (convertView == null)
            vi = inflater.inflate(R.layout.row, null);

        HashMap<String, Object> data = (HashMap<String, Object>) getItem(position);

        new DownloadTask((ImageView) vi.findViewById(R.id.imageView1))
                .execute((String) data.get("uri"));

        return vi;
    }

}

DownloadTask, :

package com.example.helpstack;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;

public class DownloadTask extends AsyncTask<String, Void, Boolean> {
    ImageView v;
    String url;
    Bitmap bm;

    public DownloadTask(ImageView v) {
        this.v = v;
    }

    @Override
    protected Boolean doInBackground(String... params) {
        url = params[0];
        bm = loadBitmap(url);
        return true;
    }

    @Override
    protected void onPostExecute(Boolean result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        v.setImageBitmap(bm);
    }

    public static Bitmap loadBitmap(String url) {
        try {
            URL newurl = new URL(url);
            Bitmap b = BitmapFactory.decodeStream(newurl.openConnection()
                    .getInputStream());
            return b;
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
}

DownloadTask getView() SimpleAdapter

MainActivity.java

package com.example.helpstack;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

public class MainActivity extends Activity {
    ListView lv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = (ListView) findViewById(R.id.listView1);
        List<Map<String, Object>> data = new ArrayList<Map<String, Object>>();
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("uri",
                "http://upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Wiktionary_small.svg/350px-Wiktionary_small.svg.png");
        //here u can add as many uri as u want
        data.add(map);
        MySimpleAdapter adapter = new MySimpleAdapter(MainActivity.this, data,
                R.layout.row, new String[] {}, new int[] {});
        lv.setAdapter(adapter);
    }
}

Answer 2

. : Picasa, .

URL-, .

http://square.imtqy.com/picasso/ https://github.com/nostra13/Android-Universal-Image-Loader

Answer 3

bitmap.please, - , android Developer . http://developer.android.com/training/multiple-threads/create-threadpool.html

Answer 4

1) Uri ImageView, ViewBinder
setViewValue

2) Picasso . setViewValue :

boolean setViewValue (View view, Object data, String textRepresentation) {
  if(view.getId() == R.id.imageView1) {
    Picasso.with(view.getContext()).load(textRepresentation).into((ImageView) view);
    return true;
  }
  return false;
}

true, . false .

3) adapter ViewBinder, adapter.setViewBinder(ViewBinder);

Answer 5

, :
1. URL- 2.
3. src . ( , ...)

Answer 6

- json- : http://www.androidbegin.com/tutorial/android-json-parse-images-and-texts-tutorial/

:

http://imagelistviewdynamic.blogspot.in/2012/12/image-parsed-from-json-using-async-into.html

http://www.java2s.com/Open-Source/Android_Free_Code/JSON/Download_Free_code_Android_JSON_Parse_Images_and_Texts_Tutorial.htm

Answer 7

I suggest you use the Universal Image Loader , it uses asynchronous image loading, caching and display, there you can find examples of how to implement it. After that, you should not worry about the number of images or its size.

If you download the project, you will find this example that does all the work you want:

/**
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 */
public class ImageListActivity extends AbsListViewBaseActivity {

    DisplayImageOptions options;

    String[] imageUrls;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ac_image_list);

            // here you get a String array with images URL
        Bundle bundle = getIntent().getExtras();
        imageUrls = bundle.getStringArray(Extra.IMAGES);

        options = new DisplayImageOptions.Builder()
            .showImageOnLoading(R.drawable.ic_stub)
            .showImageForEmptyUri(R.drawable.ic_empty)
            .showImageOnFail(R.drawable.ic_error)
            .cacheInMemory(true)
            .cacheOnDisc(true)
            .considerExifParams(true)
            .displayer(new RoundedBitmapDisplayer(20))
            .build();

        listView = (ListView) findViewById(android.R.id.list);
        ((ListView) listView).setAdapter(new ItemAdapter());
        listView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                startImagePagerActivity(position);
            }
        });
    }

    @Override
    public void onBackPressed() {
        AnimateFirstDisplayListener.displayedImages.clear();
        super.onBackPressed();
    }
    // it gets the position of listView and opens that image in a new Activity
    private void startImagePagerActivity(int position) {
        Intent intent = new Intent(this, ImagePagerActivity.class);
        intent.putExtra(Extra.IMAGES, imageUrls);
        intent.putExtra(Extra.IMAGE_POSITION, position);
        startActivity(intent);
    }

    class ItemAdapter extends BaseAdapter {

        private ImageLoadingListener animateFirstListener = new AnimateFirstDisplayListener();

        private class ViewHolder {
            public TextView text;
            public ImageView image;
        }

        @Override
        public int getCount() {
            return imageUrls.length;
        }

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

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

        @Override
        public View getView(final int position, View convertView, ViewGroup parent) {
            View view = convertView;
            final ViewHolder holder;
            if (convertView == null) {
                view = getLayoutInflater().inflate(R.layout.item_list_image, parent, false);
                holder = new ViewHolder();
                holder.text = (TextView) view.findViewById(R.id.text);
                holder.image = (ImageView) view.findViewById(R.id.image);
                view.setTag(holder);
            } else {
                holder = (ViewHolder) view.getTag();
            }

            holder.text.setText("Item " + (position + 1));
                    // here is the place where is loaded the image using Universal ImageLoader , imageUrls[position] is a list of images URL
            imageLoader.displayImage(imageUrls[position], holder.image, options, animateFirstListener);

            return view;
        }
    }

    private static class AnimateFirstDisplayListener extends SimpleImageLoadingListener {

        static final List<String> displayedImages = Collections.synchronizedList(new LinkedList<String>());

        @Override
        public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
            if (loadedImage != null) {
                ImageView imageView = (ImageView) view;
                boolean firstDisplay = !displayedImages.contains(imageUri);
                if (firstDisplay) {
                    FadeInBitmapDisplayer.animate(imageView, 500);
                    displayedImages.add(imageUri);
                }
            }
        }
    }
}