Is there a bug or something with the validation tool?

Question about the task

Chat (part 16)

Java Multithreading, Level 6, Lesson 15

Under discussion

I don't understand what is wrong with the code...

Now everything is ready for us to add the necessary methods to the SocketThread class.

1) Add a protected clientHandshake() throws IOException, ClassNotFoundException method. This method will represent the client to the server.
It must:
a) In a loop, use the connection field to receive messages.
b) If a received message is a NAME_REQUEST (the server has requested a name), use the getUserName method to ask the user to enter a username, create a new message that is a MessageType.USER_NAME and contains the entered name, and send the message to the server.
c) If a received message is a MessageType.NAME_ACCEPTED (the server has accepted the name), it means the server has accepted the client name, and you need to inform the main thread, which is eagerly waiting for this news. Do this by passing true to the notifyConnectionStatusChanged() method. Then exit the method.
d) If there is a message of any other type, throw an IOException("Unexpected MessageType").

2) Add a protected void clientMainLoop() throws IOException, ClassNotFoundException method. This method will implement the server's main message-processing loop. Inside the method:
a) Use the connection field to receive a message from the server.
b) If it is a text message (MessageType.TEXT), process it using the processIncomingMessage() method.
c) If the message is a MessageType.USER_ADDED, process it using the informAboutAddingNewUser() method.
d) If the message is a MessageType.USER_REMOVED, process it using the informAboutDeletingNewUser() method.
e) If the client receives a message of some other type, throw an IOException("Unexpected MessageType").
f) Put the code from the previous steps in an infinite loop. The loop will terminate automatically if an error (exception) occurs or the thread on which the loop is running is interrupted.

Requirements:

The clientHandshake() method should use the connection field to send a new message (MessageType.USER_NAME, getUserName()) if the received message is a MessageType.NAME_REQUEST.
The clientHandshake() method should call notifyConnectionStatusChanged(true) and terminate if the received message is a MessageType.NAME_ACCEPTED.
The clientHandshake() method should throw an IOException if the received message is not a MessageType.NAME_ACCEPTED or a MessageType.NAME_REQUEST.
The clientHandshake() method should receive messages from the server as long as the message type is MessageType.NAME_REQUEST.
The clientMainLoop() method should receive messages from the server as long as the message type is MessageType.TEXT, MessageType.USER_REMOVED, or MessageType.USER_ADDED.
The clientMainLoop() method must process the received message using the processIncomingMessage() method if the received message is a MessageType.TEXT.
The clientMainLoop() method must process the received messages using the informAboutAddingNewUser() method if the received message is a MessageType.USER_ADDED.
The clientMainLoop() method must process the received messages using the informAboutDeletingNewUser() method if the received message is a MessageType.USER_REMOVED.
The clientMainLoop() method should throw an IOException if the received message is not a MessageType.TEXT, MessageType.USER_REMOVED, or MessageType.USER_ADDED.

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.MessageType.*; public class Server { private static Map<String, Connection> connectionMap = new ConcurrentHashMap<>(); public static void sendBroadcastMessage(Message message) { for (Map.Entry<String, Connection> entry : connectionMap.entrySet()){ try{ entry.getValue().send(message); } catch (IOException e){ try{ entry.getValue().send(new Message(TEXT, "The message couldn't be sent")); } catch (IOException e2){} } } } private static class Handler extends Thread{ private Socket socket; private Handler(Socket socket) { this.socket = socket; } private String serverHandshake(Connection connection) throws IOException, ClassNotFoundException{ connection.send(new Message(NAME_REQUEST)); Message name = null; while (true){ name = connection.receive(); if (!name.getType().equals(MessageType.USER_NAME) || name.getData() == null || name.getData().isEmpty() || connectionMap.containsKey(name.getData())){ connection.send(new Message(NAME_REQUEST)); } else { break; } } connectionMap.put(name.getData(), connection); connection.send(new Message(NAME_ACCEPTED)); return name.getData(); } private void notifyUsers(Connection connection, String userName) throws IOException{ for (Map.Entry<String, Connection> entry : connectionMap.entrySet()){ if (!entry.getKey().equals(userName)){ connection.send(new Message(USER_ADDED, entry.getKey())); } } } private void serverMainLoop(Connection connection, String userName) throws IOException, ClassNotFoundException { while (true){ Message message = connection.receive(); if (message.getType().equals(TEXT)){ String text = String.format("%s: %s", userName, message.getData()); sendBroadcastMessage(new Message(TEXT, text)); } else { ConsoleHelper.writeMessage("Error!"); } } } public void run(){ ConsoleHelper.writeMessage(String.format("New connection established with remote address %s", socket.getRemoteSocketAddress())); Connection newConnection = null; String clientName = ""; do{ try { newConnection = new Connection(socket); } catch (Exception ig){ ConsoleHelper.writeMessage("An error occurred while communicating with the remote address"); break; } try { clientName = serverHandshake(newConnection); } catch (Exception ig2){ try{ newConnection.close(); ConsoleHelper.writeMessage("An error occurred while communicating with the remote address"); } catch (IOException e2){} break; } try{ sendBroadcastMessage(new Message(USER_ADDED, clientName)); notifyUsers(newConnection, clientName); serverMainLoop(newConnection, clientName); } catch (Exception e){ ConsoleHelper.writeMessage("An error occurred while communicating with the remote address"); break; } finally{ if (!clientName.equals("")){ connectionMap.remove(clientName); sendBroadcastMessage(new Message(USER_REMOVED, clientName)); } try{ newConnection.close(); } catch (IOException e){} ConsoleHelper.writeMessage("The connection with the remote address is closed."); } } while(false); } } public static void main(String[] args) throws IOException{ int serverPort = ConsoleHelper.readInt(); ServerSocket server = new ServerSocket(serverPort); System.out.println("Server is running!"); try{ while (true){ Socket socket = server.accept(); Thread handler = new Handler(socket); handler.start(); } } catch (IOException e){ System.out.println(e.getMessage()); server.close(); } } }

Comments (7)

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BlueJavaBanana

Level 37

30 September 2020, 17:02

The validator is REALLY fussy with these IF statements. What a bitch!

Anonymous #10436715

Level 38

1 May 2020, 12:56

Here is "switch" version:

protected void clientHandshake() throws IOException, ClassNotFoundException {
    while (true) {
        MessageType messageType = connection.receive().getType();
        if (messageType == null)
            throw new IOException("Unexpected MessageType");
        switch (messageType) {
            case NAME_REQUEST:
                connection.send(new Message(MessageType.USER_NAME, getUserName()));
                break;
            case NAME_ACCEPTED:
                notifyConnectionStatusChanged(true);
                return;
            default:
                throw new IOException("Unexpected MessageType");
        }
    }
}

Aleksander

Level 41 , England

28 March 2020, 14:36

protected void clientHandshake() throws IOException, ClassNotFoundException {

            while(true) {

                Message message = connection.receive();

                if(message.getType() == MessageType.NAME_REQUEST) {

                    connection.send(new Message(MessageType.USER_NAME, getUserName()));
                    continue;

                }

                if(message.getType() == MessageType.NAME_ACCEPTED) {

                    notifyConnectionStatusChanged(true);

                }

                if(message.getType() != MessageType.NAME_REQUEST && message.getType() != MessageType.NAME_ACCEPTED)
                    throw new IOException("Unexpected MessageType");

                }

        }

Roman

Level 41

22 January 2020, 12:39

Rewrite clientHandshake method via "if - else if - else"

Alexandre Lalancette

Level 41 , Quebec, Canada

22 January 2020, 16:47

I still get an error that the clientHandShake doesn't throw the Exception

Roman

Level 41

27 January 2020, 07:44

Show me your new code please.

Mateusz

Level 36 , Wroclaw, Poland

17 February 2020, 12:49

check my solution, maybe it will help you: https://codegym.cc/help/5731