Please help

Question about the task

Chat (part 6)

Java Multithreading, Level 6, Lesson 15

Resolved

Other options I've tried for the loop: 1)

catch (Exception e){
    ConsoleHelper.writeMessage("error");
    socket.close();
    serverSocket.close();
    break;
}

catch (Exception e){
    System.out.println("error");
    socket.close();
    serverSocket.close();
    break;
}

catch (Exception e){
    System.out.println("error");
    socket.close();
    break;
}

catch (Exception e){
    System.out.println(e.getMessage());
    socket.close();
    break;
}

catch (Exception e){
    System.out.println(e.getMessage());
    serverSocket.close();
    break;
}

catch (Exception e){
    ConsoleHelper.writeMessage(e.getMessage());
    serverSocket.close();
    break;
}

Edit: I added

handler.start();

between lines 19 and 20 (with all 7 options in the catch block). Still failing

Let's move on to the most important part: writing the Server class.
The server must support multiple simultaneous connections with different clients.
This can be done using the following algorithm:
- The server creates a server socket connection.
- In a loop, the server waits for some client to connect to the socket.
- It creates a new Handler thread on which messages will be exchanged with the client.
- It waits for another connection.

Add the following:
1) To the Server class, a nested private static Handler class that inherits Thread.
2) To the Handler class, a Socket socket field.
3) To the Handler class, a constructor that has a Socket parameter and uses it to initialize the appropriate field.
4) The Server's main method should:
a) Request a server port using ConsoleHelper.
b) Create a java.net.ServerSocket object using the port from the previous step.
c) Display a message indicating that the server is running.
d) In an infinite loop, listen for and accept incoming socket connections with the newly created server socket.
e) Create and start a new Handler thread, passing the socket from the previous step to the constructor.
e) Once the Handler thread is created, proceed to the next iteration of the loop.
g) Be sure that the server socket is closed if there is an exception.
h) If an Exception occurs, catch it and display an error message.

Requirements:

A private static Handler class that inherits Thread should be created in the Server class.
The Handler class must have a Socket socket field.
The Handler class constructor must have one Socket parameter and initialize the socket field.
The main() method should read the server port from the keyboard using the ConsoleHelper class's readInt() method.
The main() method should correctly implement the infinite loop described in the task conditions.

package com.codegym.task.task30.task3008; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; public class Server { public static void main(String[] args) throws IOException { ConsoleHelper.writeMessage("please enter port number"); ServerSocket serverSocket = new ServerSocket(ConsoleHelper.readInt()); System.out.println("server is running"); while (true){ Socket socket = serverSocket.accept(); try { Handler handler = new Handler(socket); } catch (Exception e){ ConsoleHelper.writeMessage(e.getMessage()); socket.close(); serverSocket.close(); break; } } } private static class Handler extends Thread{ Socket socket; Handler(Socket socket){ this.socket = socket; } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

9 March 2021, 20:50

solution

Try putting line 16 inside the try block.

Anthony Chalk

Level 30 , London, United Kingdom

9 March 2021, 20:56

Thank you. Is this necessary or is it CodeGym being pedantic? p.s. 17 attempts, think that's my new record

Guadalupe Gagnon

Level 37 , Tampa, United States

9 March 2021, 21:03

useful

That line could throw an exception. Because it is outside the try/catch structure the program would end on that uncaught exception, but the task says if any exception occurs do the stuff in your catch block. As far as real life, because this code is run with multiple threads, one thread can error out and not cause the whole application to fail. In this case you would want to ensure that the thread closes out any open streams, such as sockets, to free up the resources. Not doing so (in a very large program) could cause additional problems for the threads still running.

Anthony Chalk

Level 30 , London, United Kingdom

9 March 2021, 21:04

Thank you