android – onScroll事件没有为listview触发

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;

        }
    }
}