Question

I’m working on a project which communicate with web server and download some photos. I want these photos to be shown on a listview after the download,but it’s throwing me a NullPointerException. Here is the code I’m using :

   private ArrayList <HashMap<String, Object>> items;
    private static final String NAMEKEY = "bookname";
    private static final String INFOKEY = "bookprice";

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

        ListView listView = (ListView)findViewById(R.id.mystampii_listview);
        items = new ArrayList<HashMap<String,Object>>();
        HashMap<String, Object> hm;


        final Bitmap b = BitmapFactory.decodeFile("/sdcard/MediaCard2a44bb1f782925923195ee546e7ef395.jpg", null);
        ImageView brum = (ImageView) findViewById(R.id.main_img);
        brum.setImageBitmap(b);


        hm = new HashMap<String, Object>();
        hm.put(NAMEKEY, "Moto GP 2010");
        hm.put(INFOKEY, "98 Stampii");
        items.add(hm);

          // Define SimpleAdapter and Map the values with Row view R.layout.listbox
           SimpleAdapter adapter = new SimpleAdapter(this, items, R.layout.main_listview,
                    new String[]{NAMEKEY,INFOKEY}, new int[]{R.id.main_img,R.id.main_name, R.id.main_info});

            listView.setAdapter(adapter);
            listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    }

I know, why I’m getting NullPointerException : because my ImageView brum is placed in R.layout.main_listview and I’m setting as Content on this activity R.layout.mystampii_layout. I really can get the idea how to set the Image from SDCard to a ImageView from another layout.

Any suggestions how can I do that, or how can I show the downloaded image from SDCard in listview.

Thanks really for any kind of help!!!

Answer 1

Create your custom Adapter like this :

import java.util.ArrayList;

import com.stampii.stampii.R;
import com.stampii.stampii.comm.rpc.CollectionRPCPacket;
import com.stampii.stampii.comm.rpc.UserDatabaseHelper;

import android.app.Activity;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MyArrayAdapter extends ArrayAdapter<String> {
    private final Activity context;
    private final String[] names;
    CollectionRPCPacket rpcPacket;
    Cursor cursor;
    String title;

    public MyArrayAdapter(Activity context, String[] names) {
        super(context, R.layout.main_listview, names);
        this.context = context;
        this.names = names;
    }

    // static to save the reference to the outer class and to avoid access to
    // any members of the containing class
    static class ViewHolder {
        public ImageView imageView;
        public TextView textView,textView2;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // ViewHolder will buffer the assess to the individual fields of the row
        // layout

        ViewHolder holder;
        // Recycle existing view if passed as parameter
        // This will save memory and time on Android
        // This only works if the base layout for all classes are the same
        View rowView = convertView;
        if (rowView == null) {
            LayoutInflater inflater = context.getLayoutInflater();
            rowView = inflater.inflate(R.layout.main_listview, null, true);
            holder = new ViewHolder();
            holder.textView = (TextView) rowView.findViewById(R.id.main_name);
            holder.textView2 = (TextView) rowView.findViewById(R.id.main_info);
            holder.imageView = (ImageView) rowView.findViewById(R.id.main_img);
            rowView.setTag(holder);
        } else {
            holder = (ViewHolder) rowView.getTag();
        }
        final Bitmap b = BitmapFactory.decodeFile("/sdcard/MediaCard2a44bb1f782925923195ee546e7ef395.jpg", null);


        holder.textView.setText();
        holder.textView2.setText("");
        holder.imageView.setImageBitmap(b);


        return rowView;
    }
}

And you can use it like this on your activity :

ListView lv1 = (ListView)findViewById(R.id.listViewOne);
String[] names = new String[] { "ONE", "TWO", "THREE"};
lv1.setAdapter(new MyArrayAdapter(this, names));

Hope it helps!