Class DoubleArrayFIFOQueue

  • All Implemented Interfaces:
    DoublePriorityQueue, PriorityQueue<java.lang.Double>, java.io.Serializable

    public class DoubleArrayFIFOQueue
    extends java.lang.Object
    implements DoublePriorityQueue, java.io.Serializable
    A type-specific array-based FIFO queue, supporting also deque operations.

    Instances of this class represent a FIFO queue using a backing array in a circular way. The array is enlarged and shrunk as needed. You can use the trim() method to reduce its memory usage, if necessary.

    This class provides additional methods that implement a deque (double-ended queue).

    See Also:
    Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int INITIAL_CAPACITY
      The standard initial capacity of a queue.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Removes all elements from this queue.
      DoubleComparator comparator()
      Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
      double dequeueDouble()
      Dequeues the first element from the queue.
      double dequeueLastDouble()
      Dequeues the last element from the queue.
      void enqueue​(double x)
      Enqueues a new element.
      void enqueueFirst​(double x)
      Enqueues a new element as the first element (in dequeuing order) of the queue.
      double firstDouble()
      Returns the first element of the queue.
      double lastDouble()
      Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
      int size()
      Returns the number of elements in this queue.
      void trim()
      Trims the queue to the smallest possible size.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • INITIAL_CAPACITY

        public static final int INITIAL_CAPACITY
        The standard initial capacity of a queue.
        See Also:
        Constant Field Values
    • Constructor Detail

      • DoubleArrayFIFOQueue

        public DoubleArrayFIFOQueue​(int capacity)
        Creates a new empty queue with given capacity.
        Parameters:
        capacity - the initial capacity of this queue.
      • DoubleArrayFIFOQueue

        public DoubleArrayFIFOQueue()
        Creates a new empty queue with standard initial capacity.
    • Method Detail

      • comparator

        public DoubleComparator comparator()
        Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
        Specified by:
        comparator in interface DoublePriorityQueue
        Specified by:
        comparator in interface PriorityQueue<java.lang.Double>
        Returns:
        the comparator associated with this priority queue.
        See Also:
        PriorityQueue.comparator()
        Implementation Specification:
        This implementation returns null (FIFO queues have no comparator).
      • dequeueLastDouble

        public double dequeueLastDouble()
        Dequeues the last element from the queue.
        Returns:
        the dequeued element.
        Throws:
        java.util.NoSuchElementException - if the queue is empty.
      • enqueueFirst

        public void enqueueFirst​(double x)
        Enqueues a new element as the first element (in dequeuing order) of the queue.
        Parameters:
        x - the element to enqueue.
      • lastDouble

        public double lastDouble()
        Description copied from interface: DoublePriorityQueue
        Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).

        This default implementation just throws an UnsupportedOperationException.

        Specified by:
        lastDouble in interface DoublePriorityQueue
        Returns:
        the last element.
        See Also:
        DoublePriorityQueue.last()
      • clear

        public void clear()
        Description copied from interface: PriorityQueue
        Removes all elements from this queue.
        Specified by:
        clear in interface PriorityQueue<java.lang.Double>
      • trim

        public void trim()
        Trims the queue to the smallest possible size.
      • size

        public int size()
        Description copied from interface: PriorityQueue
        Returns the number of elements in this queue.
        Specified by:
        size in interface PriorityQueue<java.lang.Double>
        Returns:
        the number of elements in this queue.