Question

I’ve got an UDP server class which implements Runnable interface. I start it in the thread.
The problem is that I can’t stop it. Even in Debug it stops on pt.join() method.

Here is my server class

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;


public class Network implements Runnable {
final int port = 6789;

DatagramSocket socket;

byte[] input = new byte[1024];
byte[] output = new byte[1024];

public Network() throws SocketException{
    socket = new DatagramSocket(6789);
}

@Override
public void run() {
    while(true){
        DatagramPacket pack = new DatagramPacket(input,input.length);
        try {
            socket.receive(pack);
        } catch (IOException e) {
            e.printStackTrace();
        }
        input = pack.getData();
        System.out.println(new String(input));
        output = "Server answer".getBytes();
        DatagramPacket sendpack = new DatagramPacket(output,output.length,pack.getAddress(),pack.getPort());
        try {
            socket.send(sendpack);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
}

This is the main class

public class Main {

static Network network = null;

public static void main(String[] args) throws IOException{
    network = new Network();
    System.out.println("Try to start server");
    Thread pt = new Thread(network);
    pt.start();

    pt.interrupt();
    try {
        pt.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }

    System.out.println("Stop server");
}
}

How to stop server?

Answer 1

java.net reads are non-interruptible. You would have to either close the DatagramSocket or have it read with a timeout (setSoTimeout()), and when you get the resulting SocketTimeoutException check the interrupt status: if set, exit the thread.