title: How to make a UDP connection in android
body: <p>I'm trying to make a connection between my <code>galaxy tab</code> and my <code>laptop</code>. So I'm trying to run server activity on my laptop and client activity on my tab, but it doesn't work. Here is the server and client code. Where is the mistake?</p>
  
  <p><strong>SERVER:</strong></p>
  
  <pre><code>public class MainActivity extends Activity {
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      TextView txt = (TextView)findViewById(R.id.textView1);
  
      int port = 12345;
      byte [] message = new byte [1500];
      DatagramPacket p = new DatagramPacket (message,message.length);
      try {
          InetAddress serveraddr = InetAddress.getByName("192.168.1.116");
          DatagramSocket s = new DatagramSocket (port,serveraddr);
          while (true){
              s.receive(p);
              String text = new String (message,0,p.getLength());
              txt.setText(text);
          }
      } catch (SocketException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
      } catch (IOException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
      }
  }
  </code></pre>
  
  <p><strong>CLIENT:</strong></p>
  
  <pre><code>public class MainActivity extends Activity {
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      final EditText edt = (EditText)findViewById(R.id.editText1);
      Button btn = (Button)findViewById(R.id.button1);
      btn.setOnClickListener(new View.OnClickListener() {
  
          public void onClick(View arg0) {
              String msg = edt.getText().toString();
              int port = 12345;
              try {
                  DatagramSocket s = new DatagramSocket();
                  InetAddress local  = InetAddress.getByName("192.168.1.116");
                  int msg_lenght = msg.length();
                  byte []message = msg.getBytes();
                  DatagramPacket p = new DatagramPacket(message,msg_lenght,local,port);
                  s.send(p);
              } catch (SocketException e) {                   
                  e.printStackTrace();
              } catch (UnknownHostException e) {                  
                  e.printStackTrace();
              } catch (IOException e) {               
                  e.printStackTrace();
              }               
          }
      });
  }
  </code></pre>
  
  <p>Here is the <strong>log</strong>: </p>
  
  <blockquote>
    <p>09-17 23:49:55.190: D/dalvikvm(5892): Late-enabling CheckJNI 09-17
    23:49:55.690: D/CLIPBOARD(5892): Hide Clipboard dialog at Starting
    input: finished by someone else... ! 09-17 23:49:59.590:
    D/AndroidRuntime(5892): Shutting down VM 09-17 23:49:59.590:
    W/dalvikvm(5892): threadid=1: thread exiting with uncaught exception
    (group=0x40c4f1f8) 09-17 23:49:59.590: E/AndroidRuntime(5892): FATAL
    EXCEPTION: main 09-17 23:49:59.590: E/AndroidRuntime(5892):
    android.os.NetworkOnMainThreadException 09-17 23:49:59.590:
    E/AndroidRuntime(5892):   at
    android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
    09-17 23:49:59.590: E/AndroidRuntime(5892):   at
    libcore.io.BlockGuardOs.sendto(BlockGuardOs.java:175) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    libcore.io.IoBridge.sendto(IoBridge.java:463) 09-17 23:49:59.590:
    E/AndroidRuntime(5892):   at
    java.net.PlainDatagramSocketImpl.send(PlainDatagramSocketImpl.java:182)
    09-17 23:49:59.590: E/AndroidRuntime(5892):   at
    java.net.DatagramSocket.send(DatagramSocket.java:307) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    com.example.udpclient.MainActivity$1.onClick(MainActivity.java:36)
    09-17 23:49:59.590: E/AndroidRuntime(5892):   at
    android.view.View.performClick(View.java:3620) 09-17 23:49:59.590:
    E/AndroidRuntime(5892):   at
    android.view.View$PerformClick.run(View.java:14322) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    android.os.Handler.handleCallback(Handler.java:605) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    android.os.Handler.dispatchMessage(Handler.java:92) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    android.os.Looper.loop(Looper.java:137) 09-17 23:49:59.590:
    E/AndroidRuntime(5892):   at
    android.app.ActivityThread.main(ActivityThread.java:4507) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    java.lang.reflect.Method.invokeNative(Native Method) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    java.lang.reflect.Method.invoke(Method.java:511) 09-17 23:49:59.590:
    E/AndroidRuntime(5892):   at
    com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:978)
    09-17 23:49:59.590: E/AndroidRuntime(5892):   at
    com.android.internal.os.ZygoteInit.main(ZygoteInit.java:745) 09-17
    23:49:59.590: E/AndroidRuntime(5892):     at
    dalvik.system.NativeStart.main(Native Method) 09-17 23:50:34.320:
    I/Process(5892): Sending signal. PID: 5892 SIG: 9</p>
  </blockquote>