Resolve the error android.os.NetworkOnMainThreadException in an android application that works as client to receive images of a server [duplicated]

I'm trying to make an Android application that fetches an image from the computer. The server-side code (computer) is already implemented and operational. Using UDP, I ask the server to send me an image and it responds with that same image. But I can not do this. I still do not understand much from Android could someone help me to solve this problem? The error is related to threads, since I get this:

  

android.os.NetworkOnMainThreadException.

The code that I implemented on the client side, ie Android, is the following:

public class MainActivity extends ActionBarActivity {

  private final static int PACKETSIZE = 9000 ;
  public static final int SERVERPORT = 8777;
  public static final int CLIENTPORT = 8667;

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

    Button botao1;
    botao1 = (Button)findViewById(R.id.button1);

    botao1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            DatagramSocket socket = null ;

            try
            {
                InetAddress IPAddress = InetAddress.getByName("193.x.x.x");

                // Construção do socket
                socket = new DatagramSocket(CLIENTPORT) ;

                // Construção do pacote datagrama
                String msg = "imagem.jpg";
                byte [] data = msg.getBytes() ;
                DatagramPacket packet = new DatagramPacket(data, data.length, IPAddress, SERVERPORT) ;

                // Envio do pacote
                socket.send(packet) ;
                Log.d("UDP", "A enviar o pedido da imagem...");

                //Preparação da Data para recepção
                packet.setData(new byte[PACKETSIZE]);

                // Espera por uma resposta do Servidor
                socket.receive(packet) ;
                Log.d("UDP", "Imagem recebida...");

                byte[] bytearray = packet.getData();
                Log.d("UDP", " Data armazenada num bytearray");
                final Bitmap new_img = BitmapFactory.decodeByteArray(bytearray, 0,bytearray.length);
                ImageView image = (ImageView) findViewById(R.id.imageView1);
                image.setImageBitmap(new_img);

            }
            catch(Exception e)
            {
                System.out.println(e) ;
            }
            finally
            {
                if(socket != null)
                    socket.close() ;
            }   


        }
    });
  }
}