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Question about the task

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public class Server { static Map<String, Connection> connectionMap; static { connectionMap = new ConcurrentHashMap(); } public static void main(String[] args) throws IOException { int port = ConsoleHelper.readInt(); ServerSocket ss = new ServerSocket(port); ConsoleHelper.writeMessage("Server is running"); try { while (true) { // socket object to receive incoming client requests Socket s = ss.accept(); // create a new thread object Handler handler = new Handler(s); handler.start(); } } catch(Exception e){ ConsoleHelper.writeMessage(e.getMessage()); ss.close(); } } public static void sendBroadcastMessage(Message message){ for(Connection c : connectionMap.values()){ try { c.send(message); } catch (IOException e) { ConsoleHelper.writeMessage("Message couldn't be sent."); } } } private static class Handler extends Thread{ Socket socket; public Handler(Socket socket){ this.socket = socket; } } }

Because the server can work with multiple clients simultaneously, we're going to need a method to send a message to everyone all at once.

Add the following to the Server class:
1) A static Map<String, Connection> connectionMap field, where the key is the client name,
and the value is the connection with the client.
2) Initialization of the field from step 7.1 using the appropriate Map from the java.util.concurrent library,
since this field will be accessed from different threads and we need to ensure thread safety.
3) A static void sendBroadcastMessage(Message message) method, which should send the message argument
to all connections in connectionMap. If an IOException occurs while the message is being sent,
you need to catch it and inform the user that the message couldn't be sent.

Requirements:

The Server class must have a static Map connectionMap field.
The connectionMap field must be initialized using a thread-safe implementation of the Map interface from the java.util.concurrent package.
The Server class must correctly implement the static sendBroadcastMessage(Message message) method, which sends a message to all connections in connectionMap.

package com.codegym.task.task30.task3008; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; //import static com.codegym.task.task30.task3008.ConsoleHelper.writeMessage; public class Server { static Map<String, Connection> connectionMap; static { connectionMap = new ConcurrentHashMap(); } public static void main(String[] args) throws IOException { int port = ConsoleHelper.readInt(); ServerSocket ss = new ServerSocket(port); ConsoleHelper.writeMessage("Server is running"); try { while (true) { // socket object to receive incoming client requests Socket s = ss.accept(); // create a new thread object Handler handler = new Handler(s); handler.start(); } } catch(Exception e){ ConsoleHelper.writeMessage(e.getMessage()); ss.close(); } } public static void sendBroadcastMessage(Message message){ for(Connection c : connectionMap.values()){ try { c.send(message); } catch (IOException e) { ConsoleHelper.writeMessage("Message couldn't be sent."); } } } private static class Handler extends Thread{ Socket socket; public Handler(Socket socket){ this.socket = socket; } } }

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Ewerton Backend Developer

13 July 2019, 22:38

"In this and later tasks, unless specified otherwise, all of a class's fields must be private and its methods must be public." For those out there trying to resolve this problem :)