import java.util.List;

import java.util.concurrent.*;

public class Test {

private static String extractHostName(String url) {

String host = url.substring(7);

return host.indexOf("/") == -1 ? host : host.substring(0, host.indexOf("/"));

}

public static void main(String[] args) throws ExecutionException, InterruptedException {

System.out.println(extractHostName("http://news.yahoo.com/news/topics/"));

ExecutorService executorService = Executors.newFixedThreadPool(1);

Future<List<String>> listFuture = executorService.submit(new Callable<List<String>>() {

@Override

public List<String> call() throws Exception {

return null;

}

});

List<String> strings = listFuture.get();

}

}