Question

I’m pretty new to writing Android apps, and I wanted to write a piece of code that broadcasts the sensor data at a regular interval, say 1 second. Searching open-source codes I managed to write a sender class as below:

public class Sender extends Thread {
    private static final String TAG = "Sending";
    private static final int PORT = 12346;
    private static final int TIMEOUT_MS = 500;
    private static final int BUF_SIZE = 1024;
    private WifiManager mWifi;

    Sender(WifiManager wifi) {
        mWifi = wifi;
    }

    public void run() {
        try {
            DatagramSocket socket = new DatagramSocket(PORT);
            socket.setBroadcast(true);
            socket.setSoTimeout(TIMEOUT_MS);
            sendData(socket);
            socket.close();
            Thread.sleep(1000);
        }
        catch (IOException ioe) {
            Log.e(TAG, "Couldn't send data", ioe);
        } 
        catch (InterruptedException ie) {
            Log.e(TAG,  "Can't sleep", ie);
        }
    }

    private void sendData(DatagramSocket socket) throws IOException {
        byte[] buf = new byte[BUF_SIZE];
        buf = object.toString().getBytes();
        InetAddress addr = InetAddress.getByName("192.168.0.255"); // TO FIX
        DatagramPacket packet = new DatagramPacket(buf, buf.length, addr, PORT);
        socket.send(packet);
    }

    public void main(String[] args) {
        new Sender(null).start();
        while (true) {
        }
    }
}

And here’s how I start it from within the onCreate method:

public void onCreate(Bundle savedInstanceState) {
...

    new Sender((WifiManager) getSystemService(Context.WIFI_SERVICE)).start();
...
}

Now, if I open Wireshark on my laptop, I only see one packet sent at the time the app is started instead of every one second.

Could someone please point out where I did wrong? Honestly I’m not that familiar with threads and stuff, so I may just be missing something obvious here…

EDIT

OK, so the run method must be looped. See corrected code in the answer below.

Answer 1

Here’s the corrected run method code:

public void run() {
            while (true) {
                try {
                    DatagramSocket socket = new DatagramSocket(PORT);
                    socket.setBroadcast(true);
                    socket.setSoTimeout(TIMEOUT_MS);
                    sendData(socket);
                    socket.close();
                    Thread.sleep(1000);
                }
                catch (IOException ioe) {
                    Log.e(TAG, "Couldn't send data", ioe);
                } 
                catch (InterruptedException ie) {
                    Log.e(TAG,  "Can't sleep", ie);
                }
            }
}