Java Sockets #3 : Simplified Client/Server Application - Sending files from server to client

Client.java

package myjava.sockets.filetransfert;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class Client {

    private Socket socket;
    private DataInputStream in;
    private DataOutputStream out;
    private Scanner scanner;

    public Client() {
        try{
            socket = new Socket("127.0.0.1",Server.PORT);
            in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
            out = new DataOutputStream(socket.getOutputStream());
            scanner = new Scanner(System.in);

            getFile();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void getFile() throws IOException {
        String filesLen = in.readUTF();
        int maxFiles = Integer.parseInt(filesLen);
        String menu = in.readUTF();
        System.out.println(menu);

        int userSelection = 1;
        boolean isSelectionCorrect = false;
        while (!isSelectionCorrect){
            System.out.print("Select a file number: ");
            userSelection = scanner.nextInt();
            isSelectionCorrect = userSelection>0 && userSelection<= maxFiles;
        }
        out.writeUTF(""+userSelection);
        String fileContent = in.readUTF();

        System.out.println(" -- FILE START --");
        System.out.println(fileContent);
        System.out.println(" -- FILE END --");
    }

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

ClientConnection.java

package myjava.sockets.filetransfert;

import java.io.*;
import java.net.Socket;
import java.nio.file.Files;
import java.util.List;

public class ClientConnection {

    private Socket socket;
    private DataInputStream in;
    private DataOutputStream out;

    public ClientConnection(Socket socket) {
        this.socket = socket;
        try{
            in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
            out = new DataOutputStream(socket.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public void sendFile() {
        try{
            sendMenu();
            int index = getSelectedFileIndex();
            sendSelectedFile(index);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void sendSelectedFile(int index) throws IOException {
        File[] fileList = new File(Server.FILES_PATH).listFiles();
        File selectedFile = fileList[index];
        List<String> fileLines = Files.readAllLines(selectedFile.toPath());
        String fileContent = String.join("\n",fileLines);
        out.writeUTF(fileContent);
    }

    private int getSelectedFileIndex() throws IOException {
        String input = in.readUTF();
        return Integer.parseInt(input)-1;
    }

    private void sendMenu() throws IOException {
        String menu = "** Files **\n";
        File[] fileList = new File(Server.FILES_PATH).listFiles();
        out.writeUTF(""+fileList.length);

        for (int i = 0; i < fileList.length; i++) {
            menu += String.format("* %d - %s\n",i+1, fileList[i].getName());
        }
        out.writeUTF(menu);
    }

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

Server.java

package myjava.sockets.filetransfert;

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

public class Server {
    public static final String FILES_PATH = "./files/server";
    private ServerSocket serverSocket;
    public static final int PORT = 3030;

    public Server() {
        try{
            serverSocket = new ServerSocket(PORT);
            acceptConnections();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void acceptConnections() throws IOException {
        while (true){
            Socket clientSocket = serverSocket.accept();
            if(clientSocket.isConnected())
                new Thread( ()->{

                    ClientConnection client = new ClientConnection(clientSocket);
                    client.sendFile();
                    client.close();

                } ).start();
        }
    }

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