android中的自动完成功能无法使用动态数据

注意：在第一次按键时,结果将被填充.之后,如果我清除输入的文本并输入不同的字符,结果将不会显示在自动完成下拉框中.我在每次按键时从其他应用程序获取,但没有填充在自动完成下拉框中.

我尝试使用textView.showDropDown();和adapter.setNotifyOnChange(true);选项.但没用.

package com.util;

import java.io.bufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.httpentity;
import org.apache.http.httpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.httpClient;
import org.apache.http.client.methods.httpGet;
import org.apache.http.impl.client.DefaulthttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.app.Activity;
import android.os.bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;

public class HelloAutoCompleteActivity extends Activity {
List countries = new ArrayList();
    String url = ""; //some application url
AutoCompleteTextView textView;
ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceStatE) {
    super.onCreate(savedInstanceStatE);
    setContentView(R.layout.main);
    textView = (AutoCompleteTextView) findViewById(R.id.autocomplete_country);
    textView.addTextChangedListener(new CostomTextWatcher());
    textView.setThreshold(1);
    adapter = new ArrayAdapter<String>(this,R.layout.list_item,countries);
    textView.setAdapter(adapter);
}

private class CostomTextWatcher implements TextWatcher {

    @Override
    public void afterTextChanged(Editable s) {
    }

    @Override
    public void beforeTextChanged(CharSequence s,int start,int count,int after) {
    }

    @Override
    public void ontextChanged(CharSequence s,int before,int count) {
        if (s.length() > 0) {
            countries.clear();
            String readTwitterFeed = readFeed(s.toString());
            System.out.println(readTwitterFeed);
            try {
                JSONObject menuObject = new JSONObject(readTwitterFeed);
                JSONArray menuitemArray = menuObject
                        .getJSONArray("objectNameList");
                for (int i = 0; i < menuitemArray.length(); i++) {
                    System.out.println(menuitemArray.get(i));
                    countries.add(menuitemArray.get(i).toString());
                }
                // adapter.notifyDataSetChanged();
                // adapter.setNotifyOnChange(true);
                // textView.setAdapter(adapter);
                // textView.setThreshold(1);
                // textView.setAdapter(adapter);
                // textView.showDropDown();
                // adapter.setNotifyOnChange(true);
            } catch (Exception E) {
                e.printStackTrace();
            }
        }
    }
}

public String readFeed(String val) {

    StringBuilder builder = new StringBuilder();
    httpClient client = new DefaulthttpClient();
    httpGet httpGet = new httpGet(
            url);
    try {
        httpResponse response = client.execute(httpGet);
        StatusLine statusLine = response.getStatusLine();
        int statusCode = statusLine.getStatusCode();
        if (statusCode == 200) {
            System.out.println("200");
            httpentity entity = response.getEntity();
            InputStream content = entity.getContent();
            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(content));
            String line;
            while ((line = reader.readLine()) != null) {
                builder.append(linE);
            }
        } else {
            System.out.println("else block");
            Log.e(HelloAutoCompleteActivity.class.toString(),"Failed to download file");
        }
    } catch (ClientProtocolException E) {
        e.printStackTrace();
    } catch (IOException E) {
        e.printStackTrace();
    }
    return builder.toString();
}

}