Question

I am developing an app where I need to show some list view control. I am just implementing the OnScrollListener in my activity in order to monitor my listview content but it’s not invoking the onScroll event when I set the layout for my activity. If i comment that block then it invokes it just fine. How do I solve this issue?

package com.Threadtest;

import com.Threadtest.main.myRunnable;

import android.app.Activity;
import android.app.ListActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AbsListView.OnScrollListener;

public class TestList extends ListActivity implements OnScrollListener {

    Aleph0 adapter = new Aleph0();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test);
        ListView listview=(ListView)findViewById(android.R.id.list);
        listview.setAdapter(adapter);
        /*setListAdapter(adapter); 
        getListView().setOnScrollListener(this);*/
    }

    public void onScroll(AbsListView view,
        int firstVisible, final int visibleCount, int totalCount) {

        Log.i("TestList", "firstVisible="+firstVisible+" visibleCount="+visibleCount+" totalCount="+totalCount);
        boolean loadMore = /* maybe add a padding */
            firstVisible + visibleCount >= totalCount;

        if(loadMore) {
            Log.i("TestList", "In Notify");
            Thread thread = new Thread()
            {
                  @Override
                  public void run() {
                      try {
                        this.sleep(10000);
                        runOnUiThread(new myRunnable(adapter,visibleCount));
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }


                  }
              };

            thread.start();

        }
    }

    public void onScrollStateChanged(AbsListView v, int s) { } 

    class myRunnable implements Runnable
    {
        Aleph0 adapter;

        public myRunnable(Aleph0 adapter,int visibleCount)
        {

            this.adapter=adapter;
            this.adapter.count += visibleCount;
        }
        public void run() {
            // TODO Auto-generated method stub
             Log.i("TestList", "List Count="+adapter.count);
                adapter.notifyDataSetChanged();
        }

    }

    class Aleph0 extends BaseAdapter {
        int count = 40; /* starting amount */

        public int getCount() { return count; }
        public Object getItem(int pos) { return pos; }
        public long getItemId(int pos) { return pos; }

        public View getView(int pos, View v, ViewGroup p) {
            if(pos!=count-1)
            {
                TextView view = new TextView(TestList.this);
                view.setText("entry " + pos);
                return view;
            }
            TextView view = new TextView(TestList.this);
            view.setText("Loading.. " + pos);
            return view;

        }
    }
}

Answer 1

getListView().setOnScrollListener(this) is necessary to bind the listener to the ListView. The ListActivity class does not provide an “automatic” way of binding most of the listeners, It only provides an automatic way of binding the OnItemClickListener. Check out the ListActivity code.