Package it.unimi.dsi.fastutil.objects

Class ObjectArrayPriorityQueue<K>

java.lang.Object
it.unimi.dsi.fastutil.objects.ObjectArrayPriorityQueue<K>
All Implemented Interfaces:
PriorityQueue<K>, java.io.Serializable
public class ObjectArrayPriorityQueue<K>
extends java.lang.Object
implements PriorityQueue<K>, java.io.Serializable
A type-specific array-based priority queue.

Instances of this class represent a priority queue using a backing array—all operations are performed directly on the array. The array is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

See Also:
Serialized Form
Implementation Specification:
This implementation is extremely inefficient, but it is difficult to beat when the size of the queue is very small.

  • Constructor Summary

    Constructors
    Constructor Description
    ObjectArrayPriorityQueue()
    Creates a new empty queue using the natural order.
    ObjectArrayPriorityQueue​(int capacity)
    Creates a new empty queue with a given capacity and using the natural order.
    ObjectArrayPriorityQueue​(int capacity, java.util.Comparator<? super K> c)
    Creates a new empty queue with a given capacity and comparator.
    ObjectArrayPriorityQueue​(java.util.Comparator<? super K> c)
    Creates a new empty queue with a given comparator.
    ObjectArrayPriorityQueue​(K[] a)
    Wraps a given array in a queue using the natural order.
    ObjectArrayPriorityQueue​(K[] a, int size)
    Wraps a given array in a queue using the natural order.
    ObjectArrayPriorityQueue​(K[] a, int size, java.util.Comparator<? super K> c)
    Wraps a given array in a queue using a given comparator.
    ObjectArrayPriorityQueue​(K[] a, java.util.Comparator<? super K> c)
    Wraps a given array in a queue using a given comparator.

  • Method Summary

    Modifier and Type Method Description
    void changed()
    Notifies the queue that the first element has changed (optional operation).
    void clear()
    Removes all elements from this queue.
    java.util.Comparator<? super K> comparator()
    Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
    K dequeue()
    Dequeues the first element from the queue.
    void enqueue​(K x)
    Enqueues a new element.
    K first()
    Returns the first element of the queue.
    int size()
    Returns the number of elements in this queue.
    void trim()
    Trims the underlying array so that it has exactly size() elements.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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

    isEmpty, last

  • Constructor Details

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(int capacity, java.util.Comparator<? super K> c)
      Creates a new empty queue with a given capacity and comparator.
      Parameters:
      capacity - the initial capacity of this queue.
      c - the comparator used in this queue, or null for the natural order.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(int capacity)
      Creates a new empty queue with a given capacity and using the natural order.
      Parameters:
      capacity - the initial capacity of this queue.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(java.util.Comparator<? super K> c)
      Creates a new empty queue with a given comparator.
      Parameters:
      c - the comparator used in this queue, or null for the natural order.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue()
      Creates a new empty queue using the natural order.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(K[] a, int size, java.util.Comparator<? super K> c)
      Wraps a given array in a queue using a given comparator.

      The queue returned by this method will be backed by the given array.

      Parameters:
      a - an array.
      size - the number of elements to be included in the queue.
      c - the comparator used in this queue, or null for the natural order.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(K[] a, java.util.Comparator<? super K> c)
      Wraps a given array in a queue using a given comparator.

      The queue returned by this method will be backed by the given array.

      Parameters:
      a - an array.
      c - the comparator used in this queue, or null for the natural order.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(K[] a, int size)
      Wraps a given array in a queue using the natural order.

      The queue returned by this method will be backed by the given array.

      Parameters:
      a - an array.
      size - the number of elements to be included in the queue.

    • ObjectArrayPriorityQueue

      public ObjectArrayPriorityQueue​(K[] a)
      Wraps a given array in a queue using the natural order.

      The queue returned by this method will be backed by the given array.

      Parameters:
      a - an array.

  • Method Details

    • enqueue

      public void enqueue​(K x)
      Description copied from interface: PriorityQueue
      Enqueues a new element.
      Specified by:
      enqueue in interface PriorityQueue<K>
      Parameters:
      x - the element to enqueue.

    • dequeue

      public K dequeue()
      Description copied from interface: PriorityQueue
      Dequeues the first element from the queue.
      Specified by:
      dequeue in interface PriorityQueue<K>
      Returns:
      the dequeued element.

    • first

      public K first()
      Description copied from interface: PriorityQueue
      Returns the first element of the queue.
      Specified by:
      first in interface PriorityQueue<K>
      Returns:
      the first element.

    • changed

      public void changed()
      Description copied from interface: PriorityQueue
      Notifies the queue that the first element has changed (optional operation).

      This default implementation just throws an UnsupportedOperationException.

      Specified by:
      changed in interface PriorityQueue<K>

    • size

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

    • clear

      public void clear()
      Description copied from interface: PriorityQueue
      Removes all elements from this queue.
      Specified by:
      clear in interface PriorityQueue<K>

    • trim

      public void trim()
      Trims the underlying array so that it has exactly size() elements.

    • comparator

      public java.util.Comparator<? super K> comparator()
      Description copied from interface: PriorityQueue
      Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
      Specified by:
      comparator in interface PriorityQueue<K>
      Returns:
      the comparator associated with this sorted set, or null if it uses its elements' natural ordering.