import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.GenericFutureListener;

public class NettyChannelFutureDemo {
    public static void main(String[] args) {
        EmbeddedChannel channel = new EmbeddedChannel();
        for (int i = 0; i < 100; i++) {
            GenericFutureListener<Future<Object>> listener = future -> {
                System.out.println("channel closed");
            };
            channel.closeFuture().addListener(listener);
            channel.closeFuture().removeListener(listener); // not removed if netty instrumentation is on
        }
        try {
            channel.close().await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}