Example usage for java.util Queue isEmpty

Introduction

In this page you can find the example usage for java.util Queue isEmpty.

Prototype

boolean isEmpty();

Source Link

Document

Returns true if this collection contains no elements.

Usage

From source file:com.ok2c.lightmtp.examples.MailUserAgentExample.java

public static void main(final String[] args) throws Exception {

    String text1 = "From: root\r\n" + "To: testuser1\r\n" + "Subject: test message 1\r\n" + "\r\n"
            + "This is a short test message 1\r\n";
    String text2 = "From: root\r\n" + "To: testuser1, testuser2\r\n" + "Subject: test message 2\r\n" + "\r\n"
            + "This is a short test message 2\r\n";
    String text3 = "From: root\r\n" + "To: testuser1, testuser2, testuser3\r\n" + "Subject: test message 3\r\n"
            + "\r\n" + "This is a short test message 3\r\n";

    List<DeliveryRequest> requests = new ArrayList<DeliveryRequest>();
    requests.add(new BasicDeliveryRequest("root", Arrays.asList("testuser1"),
            new ByteArraySource(text1.getBytes("US-ASCII"))));
    requests.add(new BasicDeliveryRequest("root", Arrays.asList("testuser1", "testuser2"),
            new ByteArraySource(text2.getBytes("US-ASCII"))));
    requests.add(new BasicDeliveryRequest("root", Arrays.asList("testuser1", "testuser2", "testuser3"),
            new ByteArraySource(text3.getBytes("US-ASCII"))));

    MailUserAgent mua = new DefaultMailUserAgent(TransportType.SMTP, IOReactorConfig.DEFAULT);
    mua.start();/*from  w  w w.  java2 s. c o  m*/

    try {

        InetSocketAddress address = new InetSocketAddress("localhost", 2525);

        Queue<Future<DeliveryResult>> queue = new LinkedList<Future<DeliveryResult>>();
        for (DeliveryRequest request : requests) {
            queue.add(mua.deliver(new SessionEndpoint(address), 0, request, null));
        }

        while (!queue.isEmpty()) {
            Future<DeliveryResult> future = queue.remove();
            DeliveryResult result = future.get();
            System.out.println("Delivery result: " + result);
        }

    } finally {
        mua.shutdown();
    }
}

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From source file:Main.java

public static void main(String[] args) {
    Queue<String> queue = new LinkedList<>();
    queue.add("Java");
    // offer() will work the same as add()
    queue.offer("SQL");
    queue.offer("CSS");
    queue.offer("XML");

    System.out.println("Queue: " + queue);

    // Let's remove elements until the queue is empty
    while (queue.peek() != null) {
        System.out.println("Head  Element: " + queue.peek());
        queue.remove();/*from   w w  w  .j a  v  a  2  s.co m*/
        System.out.println("Removed one  element from  Queue");
        System.out.println("Queue: " + queue);
    }
    System.out.println("queue.isEmpty(): " + queue.isEmpty());
    System.out.println("queue.peek(): " + queue.peek());
    System.out.println("queue.poll(): " + queue.poll());
    try {
        String str = queue.element();
        System.out.println("queue.element(): " + str);
        str = queue.remove();
        System.out.println("queue.remove(): " + str);
    } catch (NoSuchElementException e) {
        System.out.println("queue.remove(): Queue is  empty.");
    }
}

---

From source file:io.aos.protocol.http.httpcommon.FluentAsync.java

public static void main(String... args) throws Exception {
    // Use pool of two threads
    ExecutorService threadpool = Executors.newFixedThreadPool(2);
    Async async = Async.newInstance().use(threadpool);

    Request[] requests = new Request[] { Request.Get("http://www.google.com/"),
            Request.Get("http://www.yahoo.com/"), Request.Get("http://www.apache.com/"),
            Request.Get("http://www.apple.com/") };

    Queue<Future<Content>> queue = new LinkedList<Future<Content>>();
    // Execute requests asynchronously
    for (final Request request : requests) {
        Future<Content> future = async.execute(request, new FutureCallback<Content>() {

            public void failed(final Exception ex) {
                System.out.println(ex.getMessage() + ": " + request);
            }//from   w  w  w .  jav  a 2 s.  c om

            public void completed(final Content content) {
                System.out.println("Request completed: " + request);
            }

            public void cancelled() {
            }

        });
        queue.add(future);
    }

    while (!queue.isEmpty()) {
        Future<Content> future = queue.remove();
        try {
            future.get();
        } catch (ExecutionException ex) {
        }
    }
    System.out.println("Done");
    threadpool.shutdown();
}

---

From source file:interoperabilite.webservice.fluent.FluentAsync.java

public static void main(String[] args) throws Exception {
    // Use pool of two threads
    ExecutorService threadpool = Executors.newFixedThreadPool(2);
    Async async = Async.newInstance().use(threadpool);

    Request[] requests = new Request[] { Request.Get("http://www.google.com/"),
            Request.Get("http://www.yahoo.com/"), Request.Get("http://www.apache.com/"),
            Request.Get("http://www.apple.com/") };

    Queue<Future<Content>> queue = new LinkedList<Future<Content>>();
    // Execute requests asynchronously
    for (final Request request : requests) {
        Future<Content> future = async.execute(request, new FutureCallback<Content>() {

            @Override//from  w  w w. j a  va  2 s. co m
            public void failed(final Exception ex) {
                System.out.println(ex.getMessage() + ": " + request);
            }

            @Override
            public void completed(final Content content) {
                System.out.println("Request completed: " + request);
            }

            @Override
            public void cancelled() {
            }

        });
        queue.add(future);
    }

    while (!queue.isEmpty()) {
        Future<Content> future = queue.remove();
        try {
            future.get();
        } catch (ExecutionException ex) {
        }
    }
    System.out.println("Done");
    threadpool.shutdown();
}

---

From source file:amie.keys.CSAKey.java

public static void main(String[] args) throws IOException, InterruptedException {
    final Triple<MiningAssistant, Float, String> parsedArgs = parseArguments(args);
    final Set<Rule> output = new LinkedHashSet<>();

    // Helper object that contains the implementation for the calculation
    // of confidence and support
    // The file with the non-keys, one per line
    long timea = System.currentTimeMillis();
    List<List<String>> inputNonKeys = Utilities.parseNonKeysFile(parsedArgs.third);
    System.out.println(inputNonKeys.size() + " input non-keys");
    final List<List<String>> nonKeys = pruneBySupport(inputNonKeys, parsedArgs.second,
            parsedArgs.first.getKb());//from  w  w w .ja va  2 s  . c  o  m
    Collections.sort(nonKeys, new Comparator<List<String>>() {

        @Override
        public int compare(List<String> o1, List<String> o2) {
            int r = Integer.compare(o2.size(), o1.size());
            if (r == 0) {
                return Integer.compare(o2.hashCode(), o1.hashCode());
            }

            return r;
        }

    });
    System.out.println(nonKeys.size() + " non-keys after pruning");
    int totalLoad = computeLoad(nonKeys);
    System.out.println(totalLoad + " is the total load");
    int nThreads = Runtime.getRuntime().availableProcessors();
    //int batchSize = Math.max(Math.min(maxBatchSize, totalLoad / nThreads), minBatchSize);
    int batchSize = Math.max(Math.min(maxLoad, totalLoad / nThreads), minLoad);

    final Queue<int[]> chunks = new PriorityQueue(50, new Comparator<int[]>() {
        @Override
        public int compare(int[] o1, int[] o2) {
            return Integer.compare(o2[2], o1[2]);
        }

    });

    final HashSet<HashSet<Integer>> nonKeysInt = new HashSet<>();
    final HashMap<String, Integer> property2Id = new HashMap<>();
    final HashMap<Integer, String> id2Property = new HashMap<>();
    final List<Integer> propertiesList = new ArrayList<>();
    int support = (int) parsedArgs.second.floatValue();
    KB kb = parsedArgs.first.getKb();
    buildDictionaries(nonKeys, nonKeysInt, property2Id, id2Property, propertiesList, support, kb);
    final List<HashSet<Integer>> nonKeysIntList = new ArrayList<>(nonKeysInt);
    int start = 0;
    int[] nextIdx = nextIndex(nonKeysIntList, 0, batchSize);
    int end = nextIdx[0];
    int load = nextIdx[1];
    while (start < nonKeysIntList.size()) {
        int[] chunk = new int[] { start, end, load };
        chunks.add(chunk);
        start = end;
        nextIdx = nextIndex(nonKeysIntList, end, batchSize);
        end = nextIdx[0];
        load = nextIdx[1];
    }

    Thread[] threads = new Thread[Math.min(Runtime.getRuntime().availableProcessors(), chunks.size())];
    for (int i = 0; i < threads.length; ++i) {
        threads[i] = new Thread(new Runnable() {

            @Override
            public void run() {
                while (true) {
                    int[] chunk = null;
                    synchronized (chunks) {
                        if (!chunks.isEmpty()) {
                            chunk = chunks.poll();
                        } else {
                            break;
                        }
                    }
                    System.out.println("Processing chunk " + Arrays.toString(chunk));
                    mine(parsedArgs, nonKeysIntList, property2Id, id2Property, propertiesList, chunk[0],
                            chunk[1], output);
                }

            }
        });
        threads[i].start();
    }

    for (int i = 0; i < threads.length; ++i) {
        threads[i].join();
    }
    long timeb = System.currentTimeMillis();
    System.out.println("==== Unique C-keys =====");
    for (Rule r : output) {
        System.out.println(Utilities.formatKey(r));
    }
    System.out.println(
            "VICKEY found " + output.size() + " unique conditional keys in " + (timeb - timea) + " ms");
}

---

From source file:Main.java

public static <T extends Annotation> T getAnnotation(Class<?> clazz, Class<T> aClazz) {
    //Check class hierarchy
    for (Class<?> c = clazz; c != null; c = c.getSuperclass()) {
        T anno = c.getAnnotation(aClazz);
        if (anno != null) {
            return anno;
        }/*w w w  . ja  v  a2 s  . co m*/
    }

    //Check interfaces (breadth first)
    Queue<Class<?>> q = new LinkedList<Class<?>>();
    q.add(clazz);
    while (!q.isEmpty()) {
        Class<?> c = q.remove();
        if (c != null) {
            if (c.isInterface()) {
                T anno = c.getAnnotation(aClazz);
                if (anno != null) {
                    return anno;
                }
            } else {
                q.add(c.getSuperclass());
            }
            q.addAll(Arrays.asList(c.getInterfaces()));
        }
    }

    return null;
}

---

From source file:org.apache.streams.util.ComponentUtils.java

/**
 * Certain types of queues will return null when calling {@link java.util.Queue#poll()} due to many factors depending
 * on the type of queue.  <code>pollWhileNotEmpty</code> will poll the queue until an item from the queue is returned
 * or the queue is empty.  If the queue is empty it will return NULL.
 * @param queue// ww  w.j a v a2  s.co  m
 * @param <T>
 * @return
 */
public static <T> T pollWhileNotEmpty(Queue<T> queue) {
    T item = queue.poll();
    while (!queue.isEmpty() && item == null) {
        Thread.yield();
        item = queue.poll();
    }
    return item;
}

---

From source file:Main.java

/**
 * Creates a list by pulling off the head of a queue one item at a time and
 * adding it to an output list. The input queue is emptied by this method.
 * //from w  w  w . ja  v  a2 s .  com
 * @param <T>
 * @param queue
 * @param outputList
 * @param reverse
 *            whether or not to reverse the resulting list
 * @return
 */
public static <T> List<T> createList(Queue<T> queue, List<T> outputList, boolean reverse) {
    if (outputList == null) {
        outputList = new ArrayList<T>(queue.size());
    }
    while (!queue.isEmpty()) {
        outputList.add(queue.poll());
    }
    if (reverse) {
        Collections.reverse(outputList);
    }
    return outputList;
}

---

From source file:graphs.Graphs.java

public static <V, E> String BreadthSearch(Graph<V, E> g) {
    StringBuilder b = new StringBuilder();

    Queue<V> Qu = new LinkedList<V>();
    Set<V> visited = new HashSet();
    Set<V> found = new HashSet();

    V start = (V) g.getVertices().toArray()[0];
    Qu.add(start);/*from w ww  . j a v a2  s .c  om*/
    found.add(start);

    while (!Qu.isEmpty()) {
        V vertex = Qu.remove();
        for (V neighbor : g.getNeighbors(vertex)) {
            if (!found.contains(neighbor) && !visited.contains(neighbor)) {
                found.add(neighbor);
                Qu.add(neighbor);
            }
        }
        b.append(vertex.toString() + " ");
        visited.add(vertex);
    }

    return b.toString();
}

---

From source file:fr.inria.atlanmod.emf.graphs.Connectedness.java

/**
 * Returns the {@link Set} of {@link EObject}s that can be reached by
 * navigating {@link EReference}s, starting from <code>initialEObject</code>
 * /*from www .  ja v a 2s.c om*/
 * @param initialEObject
 *            The initial {@link EObject}
 * @return The {@link Set} of reachable {@link EObject}s
 */
private static Set<EObject> getReachableEObjects(EObject initialEObject) {
    Set<EObject> visited = new HashSet<>();
    Queue<EObject> next = new LinkedList<EObject>();
    next.add(initialEObject);

    while (!next.isEmpty()) {
        EObject activeEObject = next.poll();
        if (visited.add(activeEObject)) {
            next.addAll(activeEObject.eContents());
            next.addAll(activeEObject.eCrossReferences());
        }
    }

    return visited;
}

---

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