Android: how to dynamically load resource images in a ListView?

I have a bunch of resource images, and I want to display a certain one for each element of a ListView. Currently I have a row.xml file that has each element displaying the "icon" image. I want to use the same format that I specified in row.xml, but change the image to whatever I want each time.

I have done some research on "lazy loading" but it seems like开发者_JAVA技巧 it is overly complicated and does not apply to this.

You should override the getView method of you listview's adapter so that it will return a component that will inflate your row.xml. This component can then be customized before being returned.

Here is an example :

@Override
public View getView(int position, View convertView, ViewGroup parent) 
{
    //where myview is your custom class loading your row.xml 
    if( !(convertView instanceof MyView) )
        convertView = new  MyView();

    MyView v = (MyView) convertView;
    v.setImage( <your image depending on position> );
    return convertView;
}//met

Regards, Stéphane

Ok, to expand on the answer above, you make an "adapter" like the one shown in the code below:

package com.example.consumer.adapter;

import java.util.ArrayList;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.example.consumer.R;
import com.example.consumer.model.AppModel;
import com.example.consumer.model.Deal;

public class DealListAdapter extends BaseAdapter {

    private static ArrayList<Deal> dealArrayList = new ArrayList<Deal>();

    private LayoutInflater inflator;
    private AppModel appModel;

    public DealListAdapter(Context context, ArrayList<Deal> results) {
        dealArrayList = results;
        inflator = LayoutInflater.from(context);
        appModel = (AppModel) context.getApplicationContext();
    }

    public int getCount() {
        if (dealArrayList == null)
            return 0;
        else
            return dealArrayList.size();
    }

    public Object getItem(int position) {
        try {
            return dealArrayList.get(position);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

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

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflator.inflate(R.layout.list_item_deal, null);
            holder = new ViewHolder();
            holder.name = (TextView) convertView.findViewById(R.id.deal_listview_item_one);
            holder.distance = (TextView) convertView.findViewById(R.id.deal_listview_item_two);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.name.setText(dealArrayList.get(position).getMerchantName() + ":  "+ dealArrayList.get(position).getTitle());
        holder.distance.setText(dealArrayList.get(position).getDistanceFormatted(appModel.getLocation()));

        return convertView;
    }

    static class ViewHolder {
        TextView name;
        TextView distance;
    }
}

Note the use of a ViewHolder - this will save a lot of "findViewById" Calls.

To use this adapter in your list, you use this code:

    dealList = (ListView) findViewById(R.id.browse_list_view);
    dealListAdapter = new DealListAdapter(this, dealList);
    dealList.setAdapter(dealListAdapter);

Where in this instance, the dealList is an arrayList of Deals (you would use some other custom object)

Hopefully this helps with your OO programming... :)

I found one useful example to display image in listview, gridview. Hope it will be very useful to you.

https://github.com/nostra13/Android-Universal-Image-Loader