Java Sockets #2 : Simplified Client/Server Application - Multiple connections

Client.java

package net.sockets.simplified;


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

public class Client {
    private Socket socket;
    private DataOutputStream out;
    private Scanner in;

    public Client(){
        try{
            socket = new Socket("127.0.0.1", Server.PORT);
            out = new DataOutputStream(socket.getOutputStream());
            in = new Scanner(System.in);
            writeMessages();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void writeMessages() throws IOException {
        String line = "";
        while(!line.equals(Server.STOP_STRING)){
            line = in.nextLine();
            out.writeUTF(line);
        }
        close();
    }

    private void close() throws IOException {
        socket.close();
        out.close();
        in.close();
    }

    public static void main(String[] args) {
        new Client();
    }
}

ConnectedClient.java

package net.sockets.simplified;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.net.Socket;

public class ConnectedClient {
    private Socket clientSocket;
    private DataInputStream in;
    private int id;

    public ConnectedClient(Socket clientSocket, int id) {
        this.clientSocket = clientSocket;
        this.id = id;
        try {
            System.out.println("Client "+id+ ": Client Connected");
            this.in = new DataInputStream(new BufferedInputStream(clientSocket.getInputStream()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void readMessages(){
        String line = "";
        while(!line.equals(Server.STOP_STRING)){
            try {
                line = in.readUTF();
            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println("Client "+id+ ": "+ line);
        }
        System.out.println("Client "+id+ ": Client Disconnected");
    }

    public void close(){
        try{
            clientSocket.close();
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Server.java

package net.sockets.simplified;


import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    private ServerSocket server;
    public static final int PORT = 3030;
    public static final String STOP_STRING = "##";
    private int index = 0;

    public Server(){
        try{
            server = new ServerSocket(PORT);
            while(true) iniConnections();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void iniConnections() throws IOException {
        Socket clientSocket = server.accept();

        if(clientSocket.isConnected())
        new Thread(()->{
            index++;
            ConnectedClient client = new ConnectedClient(clientSocket,index);
            client.readMessages();
            client.close();
        }).start();
    }


    public static void main(String[] args) {
        new Server();
    }
}

What if I want to Close the server manually
There STOP_STRING should be added to close ther server OR Stop the Running Server