Request and response through socket in Dart and Java

client.dart

import 'dart:convert';
import 'dart:core';
import 'dart:io';

class MySocket {
  final int port = 5000;
  final String host = "10.0.2.2";
  final String data;

  MySocket(this.data);

  Future<String> sendAndReceive() async {
    var socket = await Socket.connect(host, port);
    socket.writeln(data);
    String response = await utf8.decoder.bind(socket).join();
    socket.close();
    return response;
  }
}

server.java

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.io.DataOutputStream;
import java.util.Scanner;

public class Server {
    public static void main(String[] args) {    
        try (ServerSocket serverSocket = new ServerSocket(5000)) {
            while (true) {
                Socket socket = serverSocket.accept();
                Scanner in = new Scanner(socket.getInputStream(), "UTF-8");
                DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());
                String input = in.nextLine();
                byte[] response = null;
                outputStream.write(response);
                outputStream.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}