Dynamically increase the number of items in a list

Question

Dynamically increase the number of items in a list

I want to increase the number of elements that will be displayed in a dynamic form when the list of the list scrolls to the end. In my case, my list will display 10 items initially. then when we move on to the last element, it should start displaying 10 more items and so on. How can i do this?

Here is my custom array adapter

    package com.android.listview;

import java.util.ArrayList;

import com.android.listview.R;
import com.android.listview.Product;

import android.widget.ArrayAdapter;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.android.listview.ListViewActivity;

public class CustomArrayAdapter extends ArrayAdapter<Product> implements
        OnScrollListener {

    private final Context context;
    private final ArrayList<Product> values;

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

    public CustomArrayAdapter(Context arg0, int arg1, int arg2,
            ArrayList<Product> arg3) {
        super(arg0, arg1, arg2, arg3);
        this.context = arg0;
        this.values = arg3;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        int product_id = 0;
        View rowView = inflater.inflate(R.layout.feed_items, parent, false);
        try {

            ImageView wic_logo = (ImageView) rowView.findViewById(R.id.logo);
            TextView label = (TextView) rowView.findViewById(R.id.label);

            Product p = values.get(position);
            product_id = p.productId;
            String date = new java.text.SimpleDateFormat("dd/MM/yy")
                    .format(new java.util.Date(p.timeStamp));
            label.setText(p.productName + "\n" + p.reportedPrice + "   MRP: "
                    + p.mrp + "\n" + "Discount: " + p.discount + "%   "
                    + p.area + "  " + p.city + "\n" + "Shared by " + p.userName
                    + " " + "on" + " " + date);

            wic_logo.setImageResource(R.drawable.wic_logo_small);
            Log.d("date", "" + date);

            Log.d("Custom Array Adapter", "at" + position);
        } catch (Exception e) {
            Log.d("Custom Array Adapter", "catch");
        }

        return rowView;
    }

    public void onScroll(AbsListView arg0, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        Log.d("entered onScroll", " " + firstVisibleItem + visibleItemCount
                + totalItemCount);
        if (((firstVisibleItem + visibleItemCount) >= totalItemCount - 1)) {
            Log.d("entered if", " " + firstVisibleItem + visibleItemCount
                    + totalItemCount);
            // if we're at the bottom of the listview, load more data
            addData(totalItemCount, values.get(totalItemCount).productId);
        }
    }

    private void addData(int totalItemCount, int productId) {

        Toast.makeText(getContext(), "last item", Toast.LENGTH_SHORT).show();
    }

    public void onScrollStateChanged(AbsListView arg0, int arg1) {

    }
}

and here is my activity

package com.android.listview;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.android.listview.CustomArrayAdapter;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.Button;
import android.widget.ListView;

public class ListViewActivity extends Activity {

    static Product[] feed_products_list;
    private JSONArray JArray;
    private InputStream is;
    private StringBuilder sb;
    private String result;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button feed_button = (Button) findViewById(R.id.feedButton_feed);
        feed_button.setBackgroundResource(R.color.grey);
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://10.0.2.2/wic2/mobile/feed");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

            try {
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(is, "iso-8859-1"), 8);
                sb = new StringBuilder();
                sb.append(reader.readLine() + "\n");
                String line = "0";
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
                is.close();
                result = sb.toString();
                Log.d("result", result);
            } catch (Exception e) {
                Log.e("error", "Error in http connection" + e.toString());
            }

            Log.e("response", "response is:" + response.toString());
        } catch (Exception e) {
            Log.e("error", "Error in http connection" + e.toString());
        }

        ListView tv = (ListView) findViewById(R.id.feedListView);
        try {
            Log.d("JArray", "entered try");
            JArray = new JSONArray(result);
            int length = JArray.length();
            feed_products_list = new Product[length+1];
            Log.d("JArray", "try last line");
        } catch (JSONException e) {
            Log.d("JArray", "in catch");
            e.printStackTrace();
        }

        JSONObject jsonObj;

        for (int i = 0; i < JArray.length(); i++) {
            try {
                Log.d("jsonObj", "entered try");
                jsonObj = JArray.getJSONObject(i);
            } catch (Exception e) {
                Log.d("jsonObj", "in catch");
                continue;
            }

            try {
                Log.d("feed_products_list", "entered try");
                feed_products_list[i] = new Product(jsonObj.getInt("id"),
                        jsonObj.getString("image"),
                        jsonObj.getString("product_name"),
                        jsonObj.getString("reported_price_formated"),
                        jsonObj.getString("store_area"),
                        jsonObj.getString("store_city"),
                        jsonObj.getString("mrp"),
                        jsonObj.getString("user_name"),
                        jsonObj.getLong("reported_timestamp"),
                        jsonObj.getInt("discount"));
                Log.d("feed_products_list", feed_products_list[i].productName);
            } catch (JSONException e) {
                Log.d("feed_products_list in catch",
                        feed_products_list[i].productName);
                e.printStackTrace();
            }
        }

        tv.setAdapter(new CustomArrayAdapter(this, R.layout.feed_items,
                R.id.label, feed_products_list));


    }
}

and another problem is that I have to initialize my feed_products_list [length] array with the number of elements in the JArray. so I can’t resize the array every time I look at the last item and fill the entire list again.

+3

android android listview dynamic-data

Housefly Apr 14 '12 at 8:40

source share

6

ArrayList. @Mayank.

+2

UVM 14 . '12 8:51

scroll listener listview

ListView lv = (ListView)findViewById(R.id.list_view); 
lv.setOnScrollListener(new OnScrollListener() { 
    @Override 
    public void onScroll(AbsListView view, int firstVisibleItem,  
        int visibleItemCount, int totalItemCount) { 
        //Check if the last view is visible 
        if (view.getLastVisiblePosition()+1 == 10) { 
            //load more content 
        } 
    } 
});

feed_products_list 10 , , 10 reset CustomArrayAdapter listview. , .

+1

Mayank 14 . '12 8:45

. Android listviews - , . , getView() , , . (Andriod , , ) -

:

View rowView = convertView;
if(rowView == null) {
   // do what you are doing now to inflate view
}
// do what you are doing now to set up view

return rowView;

, , - , , , . . .

0

Konstantin Pribluda 14 . '12 8:50

ArrayList

public class CustomArrayAdapter extends ArrayAdapter<Object> {

    private final Context context;
    private final ArrayList<Product> values;

getView()

            Product p = values.get(position);

ArrayList notifyDataSetChange() :

public void addElement(Product p){
values.add(p);
notifiyDataSetChange();
}

OnScrollListener :

listView.setOnScrollListener(new OnScrollListener() { 
    @Override 
    public void onScroll(AbsListView view, int firstVisibleItem,  
        int visibleItemCount, int totalItemCount) { 

        if (totalItemCount - visibleItemCount <= firstVisibeItem + 5) { 
            //load more content 

            .....
            adpater.addElement(p);

        } 


     } 
    });

0

confucius 14 . '12 9:00

, - Lazy loading.

It is called lazy loading. I am sure that you have not tried to look for it. And I gave you an example of a GridView. This is another Listview link. Another link

0

Bhavin Apr 14 '12 at 9:09

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Reinier · Accepted Answer · 2012-04-14T09:11:51+0000

-, . Activity values ArrayList<Product>, . JArray jArray; - , , .

, ViewHolder, . vogella.com ListView; , 3.1 3.2.

CustomArrayAdapter OnScrollListener . onScroll(...) , (, ). , , values.add(product) values.addAll(products), List Product s, notifyDataSetChanged CustomArrayAdapter values.add(...) values.addAll(...).

, :

:

int length = JArray.length();
feed_products_list = new Product[length+1];

'static' feed_products_list ArrayList:

private ArrayList<Product> feed_products_list = new ArrayList<Product>();

feed_products_list[i] = new Product(jsonObj.getInt("id"), .... yadiya ... feed_products_list.add( (jsonObj.getInt( "id" ),... yadiya... `.

:

implement OnScrollListener onScroll() :

public void onScroll(AbsListView view, int firstVisibleItem,
                        int visibleItemCount, final int totalItemCount) {
    if(((firstVisibleItem + visibleItemCount) >= totalItemCount)) {

        // if we're at the bottom of the listview, load more data
        addData(totalItemCount);
    }
}

addData(long offset):

private void addData(long offset) {

    // download your data, pass the offset so you know where to start
    // and when you convert your json into `Product`s
    Product product = new Product(JSONObject.getInt("id"), ... yadiya ...);
    this.add(product);
    this.notifyDataSetChanged();

    // make sure to call notifyDataSetChanged() on your UI-Thread.
}

Dynamically increase the number of items in a list

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