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Thread: Problem controlling a ctrl + c signal by console

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    Unhappy Problem controlling a ctrl + c signal by console

    hi! first of all tell me if you doesn't understand something of my post.

    I'm programming a Java chat with a server and several clients (all of them in separate consoles). Everething is alright when I run the server, then a client, the other client...

    My problem is that I have to control the "ctrl + c" signal (in the client). In the source code I've implemented this function:

    Runtime.getRuntime().addShutdownHook(new Thread(new Runnable(){
    public void run (){
    try {
    System.out.println("Ctrl + c pressed");
    Client.disconnect(s, c);
    finalize();
    } catch (Throwable ex) {
    Logger.getLogger(Client.class.getName()).log(Level .SEVERE, null, ex);
    }
    }
    }));

    My program lets me pressed ctrl + c but it doesn't enter in this funcion because, this "Ctrl + c pressed" is never printed. That is why my server doesn't remove the client of the list...

    Does anyone know why that happend??

    Best.


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    Default Re: Problem controlling a ctrl + c signal by console

    Client.disconnect(s, c);
    What are s and c?
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    Default Re: Problem controlling a ctrl + c signal by console

    Ups sorry,

    ServerInterface s;
    Client c;

    They are only my instances of the server and the client. With that sentence I pretend to remove the client of the list which is managed by the server.

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    Default Re: Problem controlling a ctrl + c signal by console

    Quote Originally Posted by Thabby View Post
    Ups sorry,

    ServerInterface s;
    Client c;

    They are only my instances of the server and the client. With that sentence I pretend to remove the client of the list which is managed by the server.
    Alright and where do you get the keyboard strokes against Ctrl+C?
    Anyone who stops learning is old, whether at twenty or eighty. Anyone who keeps learning stays young. The greatest thing in life is to keep your mind young.

    - Henry Ford

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    Default Re: Problem controlling a ctrl + c signal by console

    What do you mean? :S

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    Default Re: Problem controlling a ctrl + c signal by console

    By "Control C", do you mean sending a SIGINT to the program via the command line? I'd recommend posting an SSCCE that demonstrates the problem. For instance, from what is posted it is unclear whether the shutdown hook is ever added during the runtime of the application.

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    Default Re: Problem controlling a ctrl + c signal by console

    I agree with copeg - a cut down example that illustrates the problem will clear things up. (and answer questions like whether the hook ever gets added.)

    As an aside I wonder about whether a shutdown hook on the client will be enough. The slings and arrows of the web are such that the client/server link might get severed without the clean disconnect() method ever getting called. So the server might need to take some action to make sure its list of clients is valid.

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    Default Re: Problem controlling a ctrl + c signal by console

    I found the problem, I used a "while(true)" loop for reading (with Scanner class) the messages that the client could send to another, and the RunTime function which cautch the signal "SIGINT". When I pressed ctrl + C (as I was a client) RunTime caught the signal but didn't give me the control line again. Now I substitute with a "do while" loop and it works. But I don't understand why. Someone can explain me why it works with the do while loop and not the other way around?

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    Default Re: Problem controlling a ctrl + c signal by console

    Quote Originally Posted by Thabby View Post
    Someone can explain me why it works with the do while loop and not the other way around?
    You have yet to give us any context to try and address your question. I presume you don't want us to guess, so please post an SSCCE

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