我正在研究 TCP 套接字。我每 1 秒从服务器接收一次数据，我需要在 ListView 的屏幕上显示它。为此，我使用了 AsyncTask。
但我经常收到 IllegalStateException 错误
我的代码：
Handler handler = new Handler();
Timer timer = new Timer();
TimerTask doAsynchronousTask = new TimerTask() {
@Override
public void run() {
finalizer = new Runnable() {
public void run() {
try {
if (navBool) {
runOnUiThread(new Runnable() {
public void run() {
new RetriveStock().execute(); // AsyncTask.
}
});
}
} catch (Exception e) {
}
}
};
handler.post(finalizer);
}
};
timer.schedule(doAsynchronousTask, 0, 1000);
// 异步任务类
public class RetriveStock extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... params) {
message = client.clientReceive(1); // Here I receive data from server and stores it in "message" string variable.
printJson(); // FUNCTION WHICH UPDATE VALUES IN 'obj' OBJECT
runOnUiThread(new Runnable() {
@Override
public void run() {
updateList();// FUNCTION WHICH UPDATE THE LISTVIEW UI.
adb.notifyDataSetChanged();
}
});
return null;
}
@Override
protected void onCancelled() {
super.onCancelled();
}
@Override
protected void onPostExecute(Void result) {
if (adb != null) {
lv.invalidateViews();
lv.setAdapter(adb);
adb.notifyDataSetChanged();
lv.requestLayout();
}
super.onPostExecute(result);
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}
// 更新 JSON 值的函数。
public void printJson() {
try {
JSONArray jsonArray = new JSONArray(message);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject json = jsonArray.getJSONObject(i);
String symbol = json.getString("Symbol_En");
User obj = new User();
boolean checkSymbol = false;
for (int j = 0; j < list.size(); j++) {
obj = list.get(j);
if (obj.getSymbol().equalsIgnoreCase(symbol)) {
checkSymbol = true;
break;
}
}
if (!checkSymbol) {
obj = new User();
obj.Symbol_En = json.getString("Symbol_En");
obj.Symbol_Ar = json.getString("Symbol_Ar");
obj.AskPrice = json.getString("Ask");
obj.BidPrice = json.getString("Bid");
obj.AskQuantity = json.getString("AskQuantity");
obj.High = json.getString("High");
obj.Low = json.getString("Low");
obj.Open = json.getString("Open");
obj.Close = json.getString("Close");
obj.PerChange = json.getString("PerChange");
obj.NetChange = json.getString("NetChange");
obj.Volume = json.getString("Volume");
obj.Ltp = json.getString("LTP");
obj.TimeStamp = json.getString("TimeStamp");
obj.symbolId = json.getString("Id");
list.add(obj);
} else {
obj.Symbol_En = json.getString("Symbol_En");
obj.AskPrice = json.getString("Ask");
obj.BidPrice = json.getString("Bid");
obj.High = high + "";
obj.Low = low + "";
obj.Open = json.getString("Open");
obj.Close = json.getString("Close");
obj.PerChange = json.getString("PerChange");
obj.NetChange = json.getString("NetChange");
obj.Volume = json.getString("Volume");
obj.Ltp = json.getString("LTP");
obj.TimeStamp = json.getString("TimeStamp");
obj.symbolId = json.getString("Id");
}
}
} catch (JSONException e1) {
e1.printStackTrace();
}
}
// 更新 LISTVIEW UI 的函数。
public void updateList() {
adb = new ArrayAdapter<User>(DefaultMarketWatch.this,
R.layout.rssitemview, list) {
@Override
public View getView(final int position, View convertView,
ViewGroup parent) {
View view = convertView;
try {
if (null == view) {
LayoutInflater vi = (LayoutInflater) DefaultMarketWatch.this
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = vi.inflate(R.layout.rssitemview, null);
}
final User u = list.get(position);
if (null != u) {
final TextView title = (TextView) view
.findViewById(R.id.symbol);
final TextView persend = (TextView) view
.findViewById(R.id.persent);
final TextView ltp = (TextView) view
.findViewById(R.id.ltp);
final TextView high = (TextView) view
.findViewById(R.id.high);
final TextView low = (TextView) view
.findViewById(R.id.low);
final TextView persendBold = (TextView) view
.findViewById(R.id.persent_bold);
final TextView persendSup = (TextView) view
.findViewById(R.id.persent_sup);
ltp.setText(u.getLtp());
title.setText(u.getSymbol());
high.setText(u.getHigh());
low.setText(u.getLow());
persend.setText(u.getPerChange());
}
} catch (Exception e) {
e.printStackTrace();
}
return view;
}
};
}