import Foundation
import Network

var sendAndReceive = SendAndReceive(host: "localhost", port: 7777, nWParameters: .tcp)

sendAndReceive.startConnection()

while sendAndReceive.running {
    sleep(1)
}

import Foundation
import Network

class SendAndReceive {
    public var running = true
    private var host:NWEndpoint.Host
    private var port:NWEndpoint.Port
    private var nWParameters: NWParameters

    init(host:NWEndpoint.Host, port:NWEndpoint.Port, nWParameters: NWParameters) {
        self.host = host
        self.port = port
        self.nWParameters = nWParameters
    }

    func startConnection() {
        let myQueue = DispatchQueue(label: "ExampleNetwork")
        let connection = NWConnection(host: host, port: port, using: nWParameters)
        connection.stateUpdateHandler = { (newState) in
            switch(newState) {
            case .ready:
                print("ready")
                self.sendMessage(connection)
            case .waiting(let error):
                print("waiting")
                print(error)
            case .failed(let error):
                print("failed")
                print(error)
            default:
                print("defaults")
                break
            }
        }
        connection.start(queue: myQueue)
        self.receive(nWConnection: connection)
    }

    func sendMessage(_ connection: NWConnection) {
        let data = "Example Send Data".data(using: .utf8)
        let completion = NWConnection.SendCompletion.contentProcessed { (error: NWError?) in
            print("送信完了")
        }
        connection.send(content: data, completion: completion)
    }

    func receive(nWConnection:NWConnection) {
        nWConnection.receive(minimumIncompleteLength: 1, maximumLength: 5, completion: { (data, context, flag, error) in
            print("receiveMessage")
            if let data = data {
                let receiveData = [UInt8](data)
                print(receiveData)
                print(flag)
                if(flag == false) {
                    self.receive(nWConnection: nWConnection)
                }
            }
            else {
                print("receiveMessage data nil")
            }
        })
    }

}

package example.java.network;

import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class ExampleReceiveAndSend {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(7777);
            System.out.println("socket create");
            Socket socket = serverSocket.accept();
            System.out.println("accept");
            byte[] data = new byte[1024];
            int dataSize = socket.getInputStream().read(data);
            System.out.println(data);
            PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true);
            printWriter.println("Example Return Data");

            System.out.println("end");            
        }
        catch(Exception e) {
            System.out.println(e);
        }
    }

}