我是

Android开发的新手,我正在尝试编写一个小应用程序,它允许我获取外部JSON文件并解析它.我得到了它的工作,但如果我尝试在后台执行它作为AsyncTask它不会工作. Eclipse给了我错误

The method findViewById(int) is undefined for the type LongOperation

在这一行：

TextView txtView1 = (TextView)findViewById(R.id.TextView01);

这是我的代码：

public class Main extends Activity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

new LongOperation().execute();

}

}

class LongOperation extends AsyncTask {

private final Context LongOperation = null;

@Override

protected String doInBackground(String... params) {

try {

URL json = new URL("http://www.corps-marchia.de/jsontest.php");

URLConnection tc = json.openConnection();

BufferedReader in = new BufferedReader(new InputStreamReader(tc.getInputStream()));

String line;

while ((line = in.readLine()) != null) {

JSONArray ja = new JSONArray(line);

JSONObject jo = (JSONObject) ja.get(0);

TextView txtView1 = (TextView)findViewById(R.id.TextView01);

txtView1.setText(jo.getString("text") + " - " + jo.getString("secondtest"));

}

} catch (MalformedURLException e) {

Toast.makeText(this.LongOperation, "Malformed URL Exception: " + e, Toast.LENGTH_LONG).show();

} catch (IOException e) {

Toast.makeText(this.LongOperation, "IO Exception: " + e, Toast.LENGTH_LONG).show();

} catch (JSONException e) {

Toast.makeText(this.LongOperation, "JSON Exception: " + e, Toast.LENGTH_LONG).show();

}

return null;

}

@Override

protected void onPostExecute(String result) {

}

protected void onPreExecute() {

}

@Override

protected void onProgressUpdate(Void... values) {

ProgressDialog pd = new ProgressDialog(LongOperation);

pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

pd.setMessage("Working...");

pd.setIndeterminate(true);

pd.setCancelable(false);

}

}

有想法该怎么解决这个吗？