在AlertDialog中使用AutoCompleteTextView不成功，

在AlertDialog中使用AutoCompleteTextView不成功，求助!!
我想实现一个单击ListActivity中的Item弹出一个AlertDialog，Dialog的View中是一个AutoCompleteTextView，绑定了一个

ArrayAdapter，但是加上这一句就报错 actvTest.addTextChangedListener(this);，大家帮我看看是啥原因?

Main.java

Java code

package net.blogjava.mobile;import java.util.HashMap;import java.util.List;import java.util.Map;import android.app.AlertDialog;import android.app.ListActivity;import android.content.DialogInterface;import android.content.DialogInterface.OnClickListener;import android.os.Bundle;import android.text.Editable;import android.text.TextWatcher;import android.view.View;import android.widget.ArrayAdapter;import android.widget.AutoCompleteTextView;import android.widget.ListView;import android.widget.SimpleAdapter;public class Main extends ListActivity implements TextWatcher{    private ArrayAdapter<String> adapter;    private AutoCompleteTextView actvTest;    private static String[] MainItems = new String[]                                               {"线路查询","站点查询","站站查询"};        private String[] items = new String[]                                        {"1","12","123","1234","12345"};        @Override    public void onCreate(Bundle savedInstanceState)     {        super.onCreate(savedInstanceState);        actvTest = (AutoCompleteTextView)findViewById(R.id.actvQuery);        actvTest.addTextChangedListener(this);  [color=#FF0000]//加上这一句就错,WHY?[/color]                List<Map<String,String>> appItems = new ArrayList<Map<String,String>>();                for(int i=0;i<MainItems.length;i++)        {            Map<String,String> item = new HashMap<String,String>();            item.put("itemname", MainItems[i]);            appItems.add(item);        }                SimpleAdapter simpleAdapter = new SimpleAdapter(this,appItems,R.layout.main,                new String[]{"itemname"},new int[]{R.id.tvMainItem});        setListAdapter(simpleAdapter);    }        @Override    protected void onListItemClick(ListView l, View v, int position, long id)     {        View testView = getLayoutInflater().inflate(R.layout.autocomplete, null);                new AlertDialog.Builder(this).setTitle("查询").setMessage("自动完成提示")            .setView(testView).setPositiveButton("确定",                     new OnClickListener()            {                @Override                public void onClick(DialogInterface dialog, int which)                 {                                                        }                            })            .setNegativeButton("取消", null).show();    }        @Override    public void afterTextChanged(Editable s)     {        /*String sql = "select BUSNUM as _id from businfo where BUSNUM like ?";        Cursor cursor = database.rawQuery(sql, new String[]                                                 {s.toString()+"%"});        TestAdapter testAdapter = new TestAdapter(this,cursor,true);        actvTest.setAdapter(testAdapter);*/        adapter = new ArrayAdapter<String>(this,                 android.R.layout.simple_dropdown_item_1line, items);         actvTest.setAdapter(adapter);    }    @Override    public void beforeTextChanged(CharSequence s, int start, int count,            int after) {        // TODO Auto-generated method stub            }    @Override    public void onTextChanged(CharSequence s, int start, int before, int count)    {        // TODO Auto-generated method stub            }        }

[解决办法]
很明显，你的两个布局文件不一样，不在一起，在findbyid前又没指定是哪个layout文件的context，默认就是this，this就是当前的上下文而在之前你有没有setContentView指定布局文件。所以空指针，是找不到AutoCompleteTextView的id。。不过貌似你的思路也有问题。。据说listview里是不能嵌套listview的。。你这里情况和这好像类似。具体我也没试过。等你效果了。。