onScroll事件未针对listview触发

Question

我正在开发一个应用程序，我需要显示一些列表视图控件。我只是在我的活动中实现OnScrollListener以监控我的listview内容，但是当我为我的活动设置布局时它没有调用onScroll事件。如果我评论该块然后它调用它就好了。我该如何解决这个问题？

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)是将侦听器绑定到ListView的必要条件。 ListActivity类不提供绑定大多数侦听器的“自动”方式，它只提供绑定OnItemClickListener的自动方式。查看ListActivity code。

Answer 2

如果您将onScroll签名更改为public void onScroll(AbsListView view, int firstVisible, int visibleCount, int totalCount)，它是否会被调用？通过添加final限定符，您已经更改了方法签名，这将导致无法看到重写的方法。将visibleCount int复制到一个新的（最终）int，以便您可以在线程中访问它。

Answer 3

import android.widget.AbsListView.OnScrollListener;

@Override 
protected void onCreate(Bundle savedInstanceState) 
{ 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.test); 

        ListView listview=(ListView)findViewById(android.R.id.list); 
        listview.setAdapter(adapter); 
        listview.setOnScrollListener(onLstScroll);    
} 


OnScrollListener onLstScroll= new OnScrollListener()
{
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
   {
       //Do something
   }

   @Override
   public void onScrollStateChanged(AbsListView view, int scrollState)
   {
      //Do something
   }
};

Answer 4

您错过了@Override和onScroll()方法上的onScrollStateChanged()表示法。