android-udp-send-receive-error

package fr.test.udp;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.os.AsyncTaskCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;

public class MainActivity extends AppCompatActivity {
    TextView debug1,debug2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new runUdpServer().start();

        debug1 = (TextView)findViewById(R.id.textView);
        debug2 = (TextView)findViewById(R.id.textView);

        debug1.setText("Start "+getIpAddress());
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        Button btn = (Button) findViewById(R.id.button);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                debug1.setText("Envoie");
                new runUdpClient("yooo").start();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    private static final int UDP_SERVER_PORT = 8051;

    private static final int MAX_UDP_DATAGRAM_LEN = 1500;
    DatagramSocket ds = null;
    public class runUdpServer extends Thread {
        public void run() {
            String lText;
            byte[] lMsg = new byte[MAX_UDP_DATAGRAM_LEN];
            DatagramPacket dp = new DatagramPacket(lMsg, lMsg.length);
            DatagramSocket ds = null;
            try {
                if (ds == null) {
                    try {
                        ds = new DatagramSocket(null);
                    } catch (SocketException e) {
                        e.printStackTrace();
                    }
                    try {
                        ds.setReuseAddress(true);
                    } catch (SocketException e) {
                        e.printStackTrace();
                    }
                    try {
                        ds.setBroadcast(true);
                    } catch (SocketException e) {
                        e.printStackTrace();
                    }
                    try {
                        ds.bind(new InetSocketAddress(UDP_SERVER_PORT));
                    } catch (SocketException e) {
                        e.printStackTrace();
                    }
                }
                //ds.setSoTimeout(100000);
                ds.receive(dp);
                lText = new String(lMsg, 0, dp.getLength());
                Log.i("UDP packet received", lText);
                debug2.setText(lText);
                ds.close();
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (ds != null) {
                    ds.close();
                }
            }
        }
    }


    public class runUdpClient extends Thread  {
        String Msg;
        public runUdpClient(String str)
        {
            super(str);
            Msg = str;
            debug1.setText("Start Client");
        }

        DatagramSocket ds = null;

        public void run() {
            if (ds == null) {
                try {
                    ds = new DatagramSocket(null);
                } catch (SocketException e) {
                    e.printStackTrace();
                }
                try {
                    ds.setReuseAddress(true);
                } catch (SocketException e) {
                    e.printStackTrace();
                }
                try {
                    ds.setBroadcast(true);
                } catch (SocketException e) {
                    e.printStackTrace();
                }
                try {
                    ds.bind(new InetSocketAddress(UDP_SERVER_PORT));
                } catch (SocketException e) {
                    e.printStackTrace();
                }
            }
            try {
                byte[] buf = new byte[30];
                buf = Msg.getBytes();
               InetAddress adrSrv = InetAddress.getByName("192.168.xxx.xxx");
                DatagramPacket packet = new DatagramPacket(buf, buf.length, adrSrv, UDP_SERVER_PORT);
                ds.send(packet);
                ds.close();
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (UnknownHostException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (ds != null) {
                    ds.close();
                }
            }
        }
    }

    private String getIpAddress() {
        String ip = "";
        try {
            Enumeration<NetworkInterface> enumNetworkInterfaces = NetworkInterface
                    .getNetworkInterfaces();
            while (enumNetworkInterfaces.hasMoreElements()) {
                NetworkInterface networkInterface = enumNetworkInterfaces
                        .nextElement();
                Enumeration<InetAddress> enumInetAddress = networkInterface
                        .getInetAddresses();
                while (enumInetAddress.hasMoreElements()) {
                    InetAddress inetAddress = enumInetAddress.nextElement();

                    if (inetAddress.isSiteLocalAddress()) {
                        ip += inetAddress.getHostAddress();
                    }

                }

            }

        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            ip += "Something Wrong! " + e.toString() + "\n";
        }

        return ip;
    }
}