Clever Geek Handbook

Ping the server without freezing the stream

I tried to use multiple threads, unfortunately no luck:

public synchronized boolean pingServer(final String ip, final short port) {
    final boolean[] returnbol = new boolean[1];
    Thread tt = new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                Socket s = new Socket(ip, port);
                s.close();
                returnbol[0] = true;
            } catch (IOException e) {
                returnbol[0] = false;
            }
        }
    });
    tt.start();
    try {
        tt.join();
    } catch (InterruptedException e) {
        tt.stop();
    }
    tt.stop();
    return returnbol[0];
}

The main thread still hangs for some reason.

Is there a "bleak" way to ping a server?

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2 answers


What exactly did you want to get in

try {
        tt.join();
    } catch (InterruptedException e) {
        tt.stop();
    }

block? Here you are connected to a parallel thread and you are waiting for that thread to end (receiving a ping result).



You have the following options:

  • Wait for the ping to finish.
  • Don't wait ... and didn't get the result.
  • Use some concurrency classes like Future <> to get the result (but you will block the thread the moment you ask for the result if you haven't got it already)
  • Or you can use the "callback" function / interface to output the result from the internal "ping" stream.
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You will need to remove the following lines from your code. Tt.join () will make the main thread wait for tt to complete.

try {
    tt.join();
} catch (InterruptedException e) {
    tt.stop();
}
tt.stop();


Use the future to get results for later use

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