我是 Android 新手，正在尝试使用 AutoCompleteTextView 和不同的适配器。使用 ArrayAdapter （在此处讨论）后，我现在正在尝试使用两个 AsyncTask 链进行相同的操作。我在其他地方看到过这种方法的几个例子，我认为它比尝试在线程之间同步数据更整洁。它还允许我保留每个项目的 K、V 哈希图，因此希望我可以在单击此应用程序下一阶段的建议时提取项目 ID。
在这种方法下，我再次努力让视图更新建议。除了我在“编辑”框中键入的内容之外，什么都没有出现。这是 UI 线程和 AsyncTask 链之间的时间问题吗？或者我在适配器/视图绑定中出错了？
注意：我已经尝试过使用 autoComplete.setAdapter(adapter); 在 ParserTask onPostExecute() 方法中应用。那也没有用。
public class MainActivity extends Activity {
public String TAG = new String("MAINACTIVITY");
public CustomAutoCompleteView autoComplete;
public InputStream inputStream;
private String serviceURL = new String("http://www.autocompare.co.uk/search.php?q=");
public QueryTask queryTask;
public ParserTask parserTask;
public SimpleAdapter adapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
autoComplete = (CustomAutoCompleteView) findViewById(R.id.autocomparesayt);
autoComplete.setHint(R.string.search_hint);
autoComplete.setThreshold(1);
autoComplete.setAdapter(adapter);
autoComplete.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(final CharSequence s, int start, int before, int count) {
int queryThreshold = 3;
if (s.length() != 2 && (s.length() - 1) % queryThreshold != 0) {
return;
}
queryTask = new QueryTask();
queryTask.execute(s.toString());
}
@Override
public void afterTextChanged(Editable s) { }
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
});
}
private class QueryTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... vehicle) {
// Go fetch data from webservice
// this bit works fine
return(data);
}
@Override
protected void onPostExecute(String result) {
Log.d(TAG, "now entered parser task");
super.onPostExecute(result);
parserTask = new ParserTask();
parserTask.execute(result);
}
}
private class ParserTask extends AsyncTask<String, Integer, List<HashMap<String, String>>> {
@Override
protected List<HashMap<String, String>> doInBackground(String... jsonData) {
List<HashMap<String, String>> vehicles = null;
VehicleJSONParser vehicleJsonParser = new VehicleJSONParser();
// parse JSON string and load data into vehicles
// this bit works fine too
return vehicles;
}
@Override
protected void onPostExecute(List<HashMap<String, String>> result) {
String[] from = {"name"};
int[] to = new int[] { android.R.id.text1 };
// Attempt to set up adapter with data bubbled up from parserTask execution
// THIS BIT LOGS NO ERRORS, BUT AUTOCOMPLETETEXTVIEW REMAINS UNCHANGED
adapter = new SimpleAdapter(getBaseContext(), result, android.R.layout.simple_list_item_1,
from, to);
adapter.notifyDataSetChanged();
}
}
}