Hi, when trying to start a socket connection in an AsyncTask, my
application crashes for no reason (debugger says
"android.view.ViewRoot$CalledFromWrongThreadException: Only the
original thread that created a view hierarchy can touch its views.").
If I remove the Async and use the same code, my application works (of
course, if I make the socket connect to a not valid IP or port, the
application freezes for 5 seconds, because that's the socket's
timeout).
As I'd like to avoid that 5 seconds freeze with wrong configurations,
I have to implement the AsyncTask.
The application works just fine opening the socket and everything
related, but as I try and make it change some TextViews, it gives this
error. The AsyncTask doc says:
"AsyncTask enables proper and easy use of the UI thread. This class
allows to perform background operations and publish results on the UI
thread without having to manipulate threads and/or handlers."
So I'm doing something legit.
This is the code, it's quite simple:
private class ConnectTask extends AsyncTask<Void, Void, Void> {
protected Void doInBackground(Void... params) {
try {
InetAddress inetAddr = InetAddress.getByName(IP);
int PORT = Integer.parseInt(Port);
if (PORT < 0)
throw (new NumberFormatException());
if (IP.equals(""))
throw (new UnknownHostException());
SocketAddress sockaddr = new InetSocketAddress(inetAddr,
PORT);
socket = new Socket();
socket.connect(sockaddr, 5000);
if (socket.isConnected()) {
OutputStreamOut = new
ObjectOutputStream(socket.getOutputStream());
InputStreamIn = new
ObjectInputStream(socket.getInputStream());
// everything worked fine until here
statusTxt.setText("App is now connected to:\n"
+ IP + " : "
+ Port); // CRASHING !!!!
connectBt.setText("Disconnect");
connected = true;
continueBt.setVisibility(0);
} else {
throw new UnknownHostException();
}
} catch (SocketTimeoutException sockExc) {
statusTxt.setText("Connection timeout:\nplease, review
your IP/
Port settings.");
} catch (NumberFormatException numExc) {
statusTxt.setText("Number Format Error:\nplease, review
your
Port settings.");
} catch (UnknownHostException e1) {
statusTxt.setText("Unknown Host Error:\nplease,
review your IP/
Port settings.");
} catch (IOException e2) {
statusTxt.setText("Input/Output Error:\nplease,
review your
connection settings.");
} finally {
//dialog.dismiss();
}
return null;
}
protected void onProgressUpdate(Void... progress) {}
protected void onPostExecute(Void result) {}
}
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