ClientHandler.java

import java.util.*;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.*;
import java.io.*;

public class ClientHandler implements Runnable {

    public static ArrayList<ClientHandler> clientHandlers = new ArrayList<>();
    private Socket socket;
    private BufferedReader bufferedReader;
    private BufferedWriter bufferedWriter;
    private String clientUsername;

    public ClientHandler(Socket socket) {
        try {
            this.socket = socket;
            this.bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            this.bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            this.clientUsername = bufferedReader.readLine();
            clientHandlers.add(this);
            broadcastMessage("Server : " + clientUsername + " has connected !");

        } catch (IOException e) {
            closeEverything(socket, bufferedReader, bufferedWriter);
        }
    }

    @Override
    public void run() {
        String messageFromClient;

        while (socket.isConnected()) {
            try {
                messageFromClient = bufferedReader.readLine();

                // parse GPX and create a partition

                broadcastMessage(messageFromClient);

            } catch (IOException e) {
                closeEverything(socket, bufferedReader, bufferedWriter);
                break;
            }
        }
    }

    public void broadcastMessage(String messageToSend) {

        // steilto se olous tous clients
        for (ClientHandler clientHandler : clientHandlers) {
            try {
                if (!clientHandler.clientUsername.equals(clientUsername)) {
                    clientHandler.bufferedWriter.write(messageToSend);
                    clientHandler.bufferedWriter.newLine();
                    clientHandler.bufferedWriter.flush();
                }
            } catch (IOException e) {
                closeEverything(socket, bufferedReader, bufferedWriter);
                break;
            }
        }

        // steilto se olous tous workers
        for (WorkerHandler workerHandler : WorkerHandler.workerHandlers) {
            try {
                if (!workerHandler.workerUsername.equals(clientUsername)) {

                    // anathesh

                    workerHandler.bufferedWriter.write(messageToSend);
                    workerHandler.bufferedWriter.newLine();
                    workerHandler.bufferedWriter.flush();
                }
            } catch (IOException e) {
                closeEverything(socket, bufferedReader, bufferedWriter);
                break;
            }
        }
    }

    public void removeClientHandler() {
        clientHandlers.remove(this);
        broadcastMessage(clientUsername + " Has left the chat");
    }

    public void closeEverything(Socket socket, BufferedReader bufferedReader, BufferedWriter bufferedWriter) {
        removeClientHandler();
        try {
            if (bufferedReader != null) {
                bufferedReader.close();
            }
            if (bufferedWriter != null) {
                bufferedWriter.close();

            }
            if (socket != null) {
                socket.close();
            }

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