Package it.unimi.dsi.fastutil.doubles

Class DoubleArrayFIFOQueue

java.lang.Object
it.unimi.dsi.fastutil.doubles.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.

  • Constructor Summary

    Constructors
    Constructor Description
    DoubleArrayFIFOQueue()
    Creates a new empty queue with standard initial capacity.
    DoubleArrayFIFOQueue​(int capacity)
    Creates a new empty queue with given capacity.

  • Method Summary

    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

    Methods inherited from interface it.unimi.dsi.fastutil.doubles.DoublePriorityQueue

    dequeue, enqueue, first, last

    Methods inherited from interface it.unimi.dsi.fastutil.PriorityQueue

    changed, isEmpty

  • Field Details

    • INITIAL_CAPACITY

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

  • Constructor Details

    • 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 Details

    • 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).

    • dequeueDouble

      public double dequeueDouble()
      Description copied from interface: DoublePriorityQueue
      Dequeues the first element from the queue.
      Specified by:
      dequeueDouble in interface DoublePriorityQueue
      Returns:
      the dequeued element.
      See Also:
      DoublePriorityQueue.dequeue()

    • dequeueLastDouble

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

    • enqueue

      public void enqueue​(double x)
      Description copied from interface: DoublePriorityQueue
      Enqueues a new element.
      Specified by:
      enqueue in interface DoublePriorityQueue
      Parameters:
      x - the element to enqueue.
      See Also:
      PriorityQueue.enqueue(Object)

    • 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.

    • firstDouble

      public double firstDouble()
      Description copied from interface: DoublePriorityQueue
      Returns the first element of the queue.
      Specified by:
      firstDouble in interface DoublePriorityQueue
      Returns:
      the first element.
      See Also:
      DoublePriorityQueue.first()

    • 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.