Class Queues

    • Method Detail

      • newArrayDeque

        public static <E> ArrayDeque<E> newArrayDeque​(Iterable<? extends E> elements)
        Creates an ArrayDeque containing the elements of the specified iterable, in the order they are returned by the iterable's iterator.
        Since:
        12.0
      • newLinkedBlockingQueue

        @GwtIncompatible
        public static <E> LinkedBlockingQueue<E> newLinkedBlockingQueue​(Iterable<? extends E> elements)
        Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE, containing the elements of the specified iterable, in the order they are returned by the iterable's iterator.
        Parameters:
        elements - the elements that the queue should contain, in order
        Returns:
        a new LinkedBlockingQueue containing those elements
      • newPriorityBlockingQueue

        @GwtIncompatible
        public static <E extends ComparablePriorityBlockingQueue<E> newPriorityBlockingQueue​(Iterable<? extends E> elements)
        Creates a PriorityBlockingQueue containing the given elements.

        Note: If the specified iterable is a SortedSet or a PriorityQueue, this priority queue will be ordered according to the same ordering.

        Since:
        11.0 (but the bound of E was changed from Object to Comparable in 15.0)
      • newPriorityQueue

        public static <E extends ComparablePriorityQueue<E> newPriorityQueue()
        Creates an empty PriorityQueue with the ordering given by its elements' natural ordering.
        Since:
        11.0 (but the bound of E was changed from Object to Comparable in 15.0)
      • newPriorityQueue

        public static <E extends ComparablePriorityQueue<E> newPriorityQueue​(Iterable<? extends E> elements)
        Creates a PriorityQueue containing the given elements.

        Note: If the specified iterable is a SortedSet or a PriorityQueue, this priority queue will be ordered according to the same ordering.

        Since:
        11.0 (but the bound of E was changed from Object to Comparable in 15.0)
      • drainUninterruptibly

        @Beta
        @CanIgnoreReturnValue
        @GwtIncompatible
        public static <E> int drainUninterruptibly​(BlockingQueue<E> q,
                                                   Collection<? super E> buffer,
                                                   int numElements,
                                                   Duration timeout)
        Drains the queue as drain(BlockingQueue, Collection, int, Duration), but with a different behavior in case it is interrupted while waiting. In that case, the operation will continue as usual, and in the end the thread's interruption status will be set (no InterruptedException is thrown).
        Parameters:
        q - the blocking queue to be drained
        buffer - where to add the transferred elements
        numElements - the number of elements to be waited for
        timeout - how long to wait before giving up
        Returns:
        the number of elements transferred
        Since:
        28.0
      • drainUninterruptibly

        @Beta
        @CanIgnoreReturnValue
        @GwtIncompatible
        public static <E> int drainUninterruptibly​(BlockingQueue<E> q,
                                                   Collection<? super E> buffer,
                                                   int numElements,
                                                   long timeout,
                                                   TimeUnit unit)
        Drains the queue as drain(BlockingQueue, Collection, int, long, TimeUnit), but with a different behavior in case it is interrupted while waiting. In that case, the operation will continue as usual, and in the end the thread's interruption status will be set (no InterruptedException is thrown).
        Parameters:
        q - the blocking queue to be drained
        buffer - where to add the transferred elements
        numElements - the number of elements to be waited for
        timeout - how long to wait before giving up, in units of unit
        unit - a TimeUnit determining how to interpret the timeout parameter
        Returns:
        the number of elements transferred
      • synchronizedQueue

        public static <E> Queue<E> synchronizedQueue​(Queue<E> queue)
        Returns a synchronized (thread-safe) queue backed by the specified queue. In order to guarantee serial access, it is critical that all access to the backing queue is accomplished through the returned queue.

        It is imperative that the user manually synchronize on the returned queue when accessing the queue's iterator:

        
         Queue<E> queue = Queues.synchronizedQueue(MinMaxPriorityQueue.<E>create());
         ...
         queue.add(element);  // Needn't be in synchronized block
         ...
         synchronized (queue) {  // Must synchronize on queue!
           Iterator<E> i = queue.iterator(); // Must be in synchronized block
           while (i.hasNext()) {
             foo(i.next());
           }
         }
         

        Failure to follow this advice may result in non-deterministic behavior.

        The returned queue will be serializable if the specified queue is serializable.

        Parameters:
        queue - the queue to be wrapped in a synchronized view
        Returns:
        a synchronized view of the specified queue
        Since:
        14.0
      • synchronizedDeque

        public static <E> Deque<E> synchronizedDeque​(Deque<E> deque)
        Returns a synchronized (thread-safe) deque backed by the specified deque. In order to guarantee serial access, it is critical that all access to the backing deque is accomplished through the returned deque.

        It is imperative that the user manually synchronize on the returned deque when accessing any of the deque's iterators:

        
         Deque<E> deque = Queues.synchronizedDeque(Queues.<E>newArrayDeque());
         ...
         deque.add(element);  // Needn't be in synchronized block
         ...
         synchronized (deque) {  // Must synchronize on deque!
           Iterator<E> i = deque.iterator(); // Must be in synchronized block
           while (i.hasNext()) {
             foo(i.next());
           }
         }
         

        Failure to follow this advice may result in non-deterministic behavior.

        The returned deque will be serializable if the specified deque is serializable.

        Parameters:
        deque - the deque to be wrapped in a synchronized view
        Returns:
        a synchronized view of the specified deque
        Since:
        15.0