UDP Client on android in LAN

Question

I have a client class which contains the edit text and the text entered will be sent to the specific host over the LAN, whose IP is defined as the button is pressed. But it is not working and it stops. Please help me. My client class is :

   public class MainActivity extends Activity {
 EditText et1;
  Button bt1;
   InetAddress IPAddress;
   DatagramPacket  dp;
   String message;
   int SERVERPORT = 11111;
      String SERVER_IP = "192.168.1.101";
   DatagramSocket clientSocket;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    et1=(EditText)findViewById(R.id.EditText01);
    bt1=(Button)findViewById(R.id.myButton);
    message=et1.getText().toString();
      try {


        clientSocket = new DatagramSocket();


    } catch (SocketException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }      
      try {


         IPAddress = InetAddress.getByName(SERVER_IP);


    } catch (UnknownHostException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }   


      byte[] sendData =  message.getBytes();

     dp = new DatagramPacket(sendData, sendData.length, IPAddress, SERVERPORT);


    bt1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub



              try {



                clientSocket.send(dp);



            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    });


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

       }

log cat is:

  08-27 07:04:52.967: D/gralloc_goldfish(531): Emulator without GPU emulation detected.
  08-27 07:05:03.018: D/AndroidRuntime(531): Shutting down VM
08-27 07:05:03.018: W/dalvikvm(531): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
   08-27 07:05:03.048: E/AndroidRuntime(531): FATAL EXCEPTION: main
  08-27 07:05:03.048: E/AndroidRuntime(531): android.os.NetworkOnMainThreadException
  08-27 07:05:03.048: E/AndroidRuntime(531):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)
     08-27 07:05:03.048: E/AndroidRuntime(531):     at libcore.io.BlockGuardOs.sendto(BlockGuardOs.java:163)
      08-27 07:05:03.048: E/AndroidRuntime(531):    at libcore.io.IoBridge.sendto(IoBridge.java:463)
 08-27 07:05:03.048: E/AndroidRuntime(531):     at java.net.PlainDatagramSocketImpl.send(PlainDatagramSocketImpl.java:182)
   08-27 07:05:03.048: E/AndroidRuntime(531):   at java.net.DatagramSocket.send(DatagramSocket.java:287)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at com.example.alastclient.MainActivity$1.onClick(MainActivity.java:73)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at android.view.View.performClick(View.java:3480)
   08-27 07:05:03.048: E/AndroidRuntime(531):   at android.view.View$PerformClick.run(View.java:13983)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at android.os.Handler.handleCallback(Handler.java:605)
     08-27 07:05:03.048: E/AndroidRuntime(531):     at android.os.Handler.dispatchMessage(Handler.java:92)
    08-27 07:05:03.048: E/AndroidRuntime(531):  at android.os.Looper.loop(Looper.java:137)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at android.app.ActivityThread.main(ActivityThread.java:4340)
 08-27 07:05:03.048: E/AndroidRuntime(531):     at java.lang.reflect.Method.invokeNative(Native Method)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at java.lang.reflect.Method.invoke(Method.java:511)
  08-27 07:05:03.048: E/AndroidRuntime(531):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
   08-27 07:05:03.048: E/AndroidRuntime(531):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-27 07:05:03.048: E/AndroidRuntime(531):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

Your client should contain the new thread for the sending the data packet on the network, In existing class you are using the main thread in order to send the udp packet over network which i guess is not a viable, you must create a new thread when button is pressed, see the android documentation for runnable and thread.