Java: How will I be able to create a Stop JButton which will stop the Runnable() thread?

Question

I have created a simple HTTP server in Java by using a ServerSocket that accepts browser requests. The server is working fine without any errors. I have created a JForm using Swing that contains buttons to start and stop the server. In the start button I have added an ActionListener that runs my ServerMain class.

btnStartServer.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
    try {
        new Thread(new Runnable() {
            public void run() { 
                ServerMain.main(new String[0]);
            }
         }).start();
        } catch (Exception e) {
        e.printStackTrace();
    }
}});

How will I be able to create a Stop JButton which will stop the Runnable() thread?

There's no guaranteed way of stopping a `Thread` other then to program the code in thread to support it. Your server should be monitoring the interrupted state of the current thread and you should have a flag (probably an `AtomicBoolean`) that you can change and check the state of to determine of the thread — MadProgrammer, Feb 07 '16 at 04:40

score 2 · Accepted Answer · edited May 23 '17 at 10:28

2

Run the server in the context of a class that implements the cancel() method of Future<V>. SwingWorker<T,V> is such a RunnableFuture<V>; a complete example is seen here.

edited May 23 '17 at 10:28

Community

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answered Feb 07 '16 at 13:36

trashgod

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Neuron · Answer 2 · 2016-02-07T19:24:38.067

You don't want to just kill a thread (by using Thread.stop()). The reasons why are listed in this article.

I assume the code in ServerMain.main(String... args) runs some kind of while(condition) loop, like this:

public class ServerMain{
    public static boolean condition = true;

    public static void main(String... args){
        while(condition){
            //do stuff
        }
        //close sockets and other streams.
        //Call Thread.interupt() on all sleeping threads
    }
}

Your button should set this condition to false somehow:

stopButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent ae) {
        try {
            new Thread() {
                public void run() {
                    // set condition to false;
                    ServerMain.condition = false;
                }
            }.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
});

Java: How will I be able to create a Stop JButton which will stop the Runnable() thread?

2 Answers2