Android TCP client

Question

I'm currently working on a tcp client in Android. I want to connect my android device to a tcp server on my computer and receive the data once every 2 seconds. The problem is that I'm getting force close on my application because of the while loop that I've implemented in the tcp client. I've tried writing in different ways the loop that will make the tcp client checking the server socket, but with no success. How can make a loop that will check the server socket without getting the force close?

Here's my code that I'm currently using:

    public class Connection implements Runnable {
    @Override
    public void run() {         
        try {                    
            sk=new Socket(server,port);
            viewsurface.setText("connected");       
            flag = true;
        } catch (UnknownHostException e) {      
            viewsurface.setText("failed 1 socket");
            flag = false;
        } catch (IOException e) {                   
            viewsurface.setText("failed 2 socket");
            flag = false;
        }

        while (flag == true){               
            try {
                checkin = sk.getInputStream();
                checkint = checkin.available();

                if (checkint > 0){
                    try {
                        BufferedReader in = new BufferedReader(new InputStreamReader(sk.getInputStream()));
                        received = in.readLine();
                        viewsurface.setText(received);

                    } catch (IOException e) {
                        viewsurface.setText("failed to receive");
                    }
                }

            Thread.sleep(2000);
            } catch (IOException e) {
                viewsurface.setText("checkin failed");

            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        }
}

}

Answer 1

You need to paste the exception that you are getting to cause the force close, before anyone can provide decent help.

But some suggestions that might solve the problem.

• Most likely to be the problem, viewText.setText can only be called from the UI thread. There's quite a few ways to handle this. You can use AsyncTask or if you have an Activity reference you can use runOnUIThread and pass in a runnable that calls setText.
• Move checkin = sk.getInputStream(); to before the loop. There's no reason to get the strem every cycle through the loop.
• Do not create the BufferedReader every cycle through the loop. Move it before the loop
• .sleep(2000) does not guarantee exactly 2 seconds.

I'm having some code formatting issues so I apologize.

 private class DownloadFilesTask extends AsyncTask<Void, String, Void> {
     protected Long doInBackground(Void... nothing) {
         try {                    
            sk=new Socket(server,port);
        publishProgress("connected");       
            flag = true;
    } catch (UnknownHostException e) {      
        publishProgress("failed 1 socket");
        flag = false;
    } catch (IOException e) {                   
        publishProgress("failed 2 socket");
        flag = false;
    }

    while (flag == true){               
        try {
            checkin = sk.getInputStream();
            checkint = checkin.available();

            if (checkint > 0){
                try {
                    BufferedReader in = new BufferedReader(new InputStreamReader(sk.getInputStream()));
                    received = in.readLine();
                    publishProgress(received);

                } catch (IOException e) {
                    publishProgress("failed to receive");
                }
            }

        Thread.sleep(2000);
        } catch (IOException e) {
            updateProgress(

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    return;
 }

 protected void onProgressUpdate(String... progress) {
    viewsurface.setText(progress[0]);
 }

 protected void onPostExecute(Void result) {
     //nothing
 }

 }