please help!

Question about the task

Chat (part 16)

Java Multithreading, Level 6, Lesson 15

Under discussion

not been able to validate with the tow throw IOException conditions for both the methods.

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.net.Socket; import java.net.ServerSocket; import java.io.*; import java.util.Map; import java.util.concurrent.ConcurrentHashMap;; import java.net.SocketAddress; 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); if(ss != null) { System.out.println("Server is running"); } Socket s = null; try { while(true){ // socket object to receive incoming client requests s = ss.accept(); // create a new thread object Thread t = new Handler(s); t.start(); } } catch (Exception e){ System.out.println(e.getMessage()); ss.close(); s.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 { //String str; //boolean nameAlreadyExist = false; Message response; while(true){ connection.send(new Message(MessageType.NAME_REQUEST)); response = connection.receive(); if (response.getType().equals(MessageType.USER_NAME)) { String data = response.getData(); if (data != null && !(data.isEmpty())) { if(!(connectionMap.containsKey(data))) { connectionMap.put(data, connection); connection.send(new Message(MessageType.NAME_ACCEPTED)); return data; } } } } } 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(MessageType.USER_ADDED,entry.getKey())); } } } private void serverMainLoop(Connection connection, String userName) throws IOException, ClassNotFoundException { while(true){ try{ Message response = connection.receive(); if(response.getType().equals(MessageType.TEXT)){ String data = userName + ": " + response.getData(); sendBroadcastMessage(new Message(MessageType.TEXT,data)); }else{ ConsoleHelper.writeMessage("Error in receiving message"); } }catch(Exception e){ System.out.println(e.getMessage()); } } } public void run(){ Connection connection = null; String userName = null; do { try { ConsoleHelper.writeMessage("New connection was established with a remote address " + socket.getRemoteSocketAddress()); connection = new Connection(socket); } catch (Exception ig) { break; } try { userName = serverHandshake(connection); } catch (Exception ig) { try { connection.close(); } catch (IOException e) { e.printStackTrace(); } break; } try { sendBroadcastMessage(new Message(MessageType.USER_ADDED, userName)); notifyUsers(connection, userName); serverMainLoop(connection, userName); } catch (Exception e) { } finally { connectionMap.remove(userName); sendBroadcastMessage(new Message(MessageType.USER_REMOVED, userName)); try { connection.close(); } catch (IOException e1) { e1.printStackTrace(); } } } while (false); ConsoleHelper.writeMessage("Connection closed: " + socket.getRemoteSocketAddress()); /*Connection connection = null; String userName = null; try{ //get remote address ConsoleHelper.writeMessage("A connection has been established with the remote adddress " + socket.getRemoteSocketAddress()); //Make the connection connection = new Connection(socket); //establishes connection with new user userName = serverHandshake(connection); sendBroadcastMessage(new Message(MessageType.USER_ADDED,userName)); notifyUsers(connection,userName); serverMainLoop(connection,userName); }catch(IOException e){ //System.out.println(e.getMessage()); try{ /*if(userName != null ){ connectionMap.remove(userName); connection.send(new Message(MessageType.USER_REMOVED)); } if(connection != null){ connection.close(); ConsoleHelper.writeMessage("The connection with the remote address is closed"); } }catch(Exception except){ except.printStackTrace(); } }catch(ClassNotFoundException e1) { System.out.println("An error occured while communication with the remote address"); try{ /*if(userName != null){ connectionMap.remove(userName); connection.send(new Message(MessageType.USER_REMOVED)); } if(connection != null){ try{ connection.close(); ConsoleHelper.writeMessage("The connection with the remote address is closed"); }catch(Exception ex1){ ex1.printStackTrace(); } } }catch(Exception en){ en.printStackTrace(); } }finally{ try{ if(userName != null){ connectionMap.remove(userName); connection.send(new Message(MessageType.USER_REMOVED)); } }catch(Exception x){ } } ConsoleHelper.writeMessage("Connection closed: " + socket.getRemoteSocketAddress());*/ } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

15 November 2019, 14:29

Instead of an infinite loop, try a loop that will run as long as the thread is not interrupted.