How can I connect two Android device by socket without server

Question

I am trying to develop an android application that can exchange data on peer to peer connection with other devices without server. So please suggest how can I do this. Thank you

Answer 1

This is a complete code for chat by SocketProgramming without server.

In my Application, first you are a client and you search for a server. When you do not find any server, you become a server and wait for a client.

public class MainActivity extends ActionBarActivity {

private Handler handler = new Handler();
private TextView text;
private EditText input;
private Button send;
private Socket socket;
private DataOutputStream outputStream;
private BufferedReader inputStream;
private String DeviceName = "Device";

private boolean searchNetwork() {
    log("Connecting");
    String range = "192.168.56.";
    for (int i = 1; i <= 255; i++) {
        String ip = range + i;
        try {
            socket = new Socket();
            socket.connect(new InetSocketAddress(ip, 9000), 50);
            outputStream = new DataOutputStream(socket.getOutputStream());
            inputStream = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            DeviceName += "1";
            Log.i("Server", DeviceName);
            log("Connected");
            return true;
        } catch (Exception e) {
        }
    }
    return false;

}

private void runNewChatServer() {
    ServerSocket serverSocket;
    try {
        serverSocket = new ServerSocket(9000);
        log("Waiting for client...");
        socket = serverSocket.accept();
        DeviceName += "2";
        log("a new client Connected");
    } catch (IOException e) {
    }

}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    text = (TextView) findViewById(R.id.text);
    input = (EditText) findViewById(R.id.input);
    send = (Button) findViewById(R.id.send);
    Thread thread = new Thread(new Runnable() {

        @Override
        public void run() {
            try {
                if (!searchNetwork()) {
                    runNewChatServer();

                }

                outputStream = new DataOutputStream(
                        socket.getOutputStream());
                inputStream = new BufferedReader(new InputStreamReader(
                        socket.getInputStream()));
                while (true) {

                    String Message = inputStream.readLine();
                    if (Message != null) {
                        log(Message);
                    }
                }
            } catch (IOException e) {
                log("Error: IO Exception");
                e.printStackTrace();
            }
        }
    });
    send.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            if (outputStream == null) {
                return;
            }
            try {
                String Message = input.getText().toString() + "\n";
                outputStream.write(Message.getBytes());
                log2(input.getText().toString());
            } catch (IOException e) {
                e.printStackTrace();
            }
            input.setText("");
        }
    });
    thread.start();

}

private void log(final String message) {
    handler.post(new Runnable() {
        String DeviceName2="";
        @Override
        public void run() {
            if (DeviceName.equals("Device1")) {
                DeviceName2 = "Device2";
            }else if(DeviceName.equals("Device2")) {
                DeviceName2 = "Device1";
            }else{
                DeviceName2 = "UnknowDevice";
            }

            text.setText(text.getText() + "\n" + DeviceName2 + " :"
                    + message);

        }
    });
}
private void log2(final String message) {
    handler.post(new Runnable() {

        @Override
        public void run() {


            text.setText(text.getText() + "\n" + "you" + " :"
                    + message);

        }
    });
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        if (socket != null) {
            try {
                socket.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.exit(0);
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

}