I don't see any variable that are not already final unless the executor service, but putting volatile on it (even if I don't see why I would do that) doesn't change the output. I also don't understand why the validation tells me to be sure the urls are here because they are obviously here. Well, I'm a bit lost on this one...
package com.codegym.task.task26.task2606;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/*
Those who love work need no entertainment
*/
public class Solution {
private final URL codegymUrl;
private final URL codegymUrl1Child;
private final URL codegymFbGroupUrl;
private final URL codegymFbGroupUrl1Child;
private final URL codegymFbGroupUrl2Child;
private final URL codegymFbGroupUrl3Child;
private volatile ExecutorService executorService;
private final Set<URL> urlsForProcessing = Collections.synchronizedSet(new HashSet<>());
public static void main(String[] args) throws MalformedURLException, InterruptedException {
Solution solution = new Solution();
solution.start();
Thread.sleep(1000);
solution.stop();
}
public Solution() throws MalformedURLException {
codegymUrl = new URL("http://codegym.cc/");
codegymFbGroupUrl = new URL("https://www.facebook.com/codegym.cc/");
codegymUrl1Child = new URL("https://codegym.cc/about/faq");
codegymFbGroupUrl1Child = new URL("https://plus.google.com/u/0/112826988801758485947/about");
codegymFbGroupUrl2Child = new URL("https://www.facebook.com/pg/codegym.cc/notes");
codegymFbGroupUrl3Child = new URL("https://twitter.com/codegym_cc");
urlsForProcessing.add(codegymUrl);
urlsForProcessing.add(codegymFbGroupUrl);
}
public synchronized void start() {
executorService = Executors.newCachedThreadPool();
for (URL url : urlsForProcessing) {
submitUrlTask(url);
}
urlsForProcessing.clear();
}
public synchronized void stop() throws InterruptedException {
try {
saveUnprocessedUrls(executorService.shutdownNow());
if (executorService.awaitTermination(1_000, TimeUnit.MILLISECONDS)) {
saveUnprocessedUrls(getCancelledTasksFromExecutor());
}
} finally {
executorService = null;
}
}
private List<Runnable> getCancelledTasksFromExecutor() {
return Collections.EMPTY_LIST;
}
protected List<URL> processPage(URL url) {
System.out.println(url + " will be processed");
return getChildUrlByParent(url);
}
private List<URL> getChildUrlByParent(URL url) {
List<URL> result = new ArrayList<>();
if (codegymUrl.equals(url)) {
result.add(codegymUrl1Child);
} else if (codegymFbGroupUrl.equals(url)) {
result.add(codegymFbGroupUrl1Child);
result.add(codegymFbGroupUrl2Child);
result.add(codegymFbGroupUrl3Child);
}
return result;
}
private void saveUnprocessedUrls(List<Runnable> unprocessed) {
for (Runnable task : unprocessed) {
urlsForProcessing.add(((UrlTask) task).getPage());
}
}
private void submitUrlTask(URL url) {
executorService.execute(new UrlTask(url));
}
public class UrlTask implements Runnable {
private final URL url;
private UrlTask(URL url) {
this.url = url;
}
public void run() {
for (URL link : processPage(url)) {
if (Thread.currentThread().isInterrupted()) return;
submitUrlTask(link);
}
}
public URL getPage() {
return url;
}
}
}