is it bugged?

Question about the task

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public class ClientGuiModel extends Client{ private final Set<String> allUserNames = new LinkedHashSet<>(); private String newMessage; public Set<String> getAllUserNames() { return Collections.unmodifiableSet(new LinkedHashSet<>(allUserNames)); } public String getNewMessage() { return newMessage; } public void setNewMessage(String newMessage) { this.newMessage = newMessage; } public void addUser(String newUserName){ allUserNames.add(newUserName); } public void deleteUser(String userName){ allUserNames.remove(userName); } }

We've already implemented a console-based client and a chat bot. Why not a client with a GUI? It will also work with our server, but it will have a graphic window, buttons, etc. Well, let's get started. The Model-View-Controller (MVC) pattern is well suited for a GUI-based client. You should have become acquainted with this pattern already. If necessary, use the Internet to refresh your knowledge of MVC. In our task, the class responsible for the model will have the simplest implementation.

Let's write it:
1) Create a new ClientGuiModel class in the client package. All client-related classes should be created in this package.
2) Add a set of strings as a final allUserNames field. It will store a list of all the chat participants. Initialize it.
3) Add a String newMessage field, which will store the new message received by the client.
4) Add an allUserNames getter that prevents modification of the returned Set. Figure out how this can be done using a method of the Collections class.
5) Add a setter and a getter for the newMessage field.
6) Add a void addUser(String newUserName) method that adds the participant's name to a set containing all the participants.
7) Add a void deleteUser(String userName) method that removes the participant's name from the set.

Requirements:

The ClientGuiModel class must be created in the client package.
The allUserNames set of strings must be initialized and declared with the private final modifier.
The private newMessage field must be a String.
A proper getter for the allUserNames field must be created in the ClientGuiModel class.
The ClientGuiModel class must have a correct getter and setter for the newMessage field.
The addUser() method should add the new username to the allUserNames set.
The deleteUser method should remove the passed username from the allUserNames set.

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 java.util.jar.Attributes; import static com.codegym.task.task30.task3008.MessageType.*; //import static com.codegym.task.task30.task3008.ConsoleHelper.writeMessage; public class Server { private 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; } private String serverHandshake(Connection connection) throws IOException, ClassNotFoundException { Message m1; String x; do{ connection.send(new Message(MessageType.NAME_REQUEST)); m1 = connection.receive(); x = m1.getData(); } while(m1.getType() != MessageType.USER_NAME || x == "" || connectionMap.containsKey(x)); connectionMap.put(x, connection); connection.send(new Message(MessageType.NAME_ACCEPTED)); return x; } private void notifyUsers(Connection connection, String userName) throws IOException { for (String name : connectionMap.keySet()){ if(!(name.equals(userName))) { Message m = new Message(MessageType.USER_ADDED, name); connection.send(m); } } } private void serverMainLoop(Connection connection, String userName) throws IOException, ClassNotFoundException { while(true) { Message m = connection.receive(); if (m.getType() == MessageType.TEXT) { Message m1 = new Message(TEXT, userName + ": " + m.getData()); sendBroadcastMessage(m1); } else ConsoleHelper.writeMessage("Error"); } } public void run(){ String userName = null; Connection myConnect = null; for (int i = 0; i < 1; i++) { try { ConsoleHelper.writeMessage("New connection was established with a remote address " + socket.getRemoteSocketAddress().toString()); myConnect = new Connection(socket); } catch (Exception ig) { break; } try { userName = serverHandshake(myConnect); } catch (Exception ig) { try { myConnect.close(); } catch (IOException e) { e.printStackTrace(); } break; } try { sendBroadcastMessage(new Message(MessageType.USER_ADDED, userName)); notifyUsers(myConnect, userName); serverMainLoop(myConnect, userName); } catch (Exception e) { } finally { connectionMap.remove(userName); sendBroadcastMessage(new Message(MessageType.USER_REMOVED, userName)); try { myConnect.close(); } catch (IOException e1) { e1.printStackTrace(); } } } ConsoleHelper.writeMessage("Connection closed: "+socket.getRemoteSocketAddress().toString()); } } }

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Bill Wu

Level 29 , Wellington, New Zealand

1 May 2019, 02:46

solution

in public Set<String> getAllUserNames(), why would you write return Collections.unmodifiableSet(new LinkedHashSet<>(allUserNames)) instead of simple allUserNames? Change it and it will pass, although I don't know why.

Djole

Level 41 , Belgrade, Serbia

1 May 2019, 08:44

Thanks. I thought getter was okay. It was reporting that addUser method().was wrong