Package it.unimi.dsi.fastutil

Class PriorityQueues.EmptyPriorityQueue

java.lang.Object
it.unimi.dsi.fastutil.PriorityQueues.EmptyPriorityQueue
All Implemented Interfaces:
PriorityQueue, java.io.Serializable
Enclosing class:
PriorityQueues
public static class PriorityQueues.EmptyPriorityQueue
extends java.lang.Object
implements PriorityQueue, java.io.Serializable
An immutable class representing the empty priority queue.

This class may be useful to implement your own in case you subclass PriorityQueue.

See Also:
Serialized Form

  • 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.lang.Object clone()  
    java.util.Comparator<?> comparator()
    Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
    java.lang.Object dequeue()
    Dequeues the first element from the queue.
    void enqueue​(java.lang.Object o)
    Enqueues a new element.
    boolean equals​(java.lang.Object o)  
    java.lang.Object first()
    Returns the first element of the queue.
    int hashCode()  
    boolean isEmpty()
    Checks whether this queue is empty.
    java.lang.Object last()
    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.

    Methods inherited from class java.lang.Object

    getClass, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • enqueue

      public void enqueue​(java.lang.Object o)
      Description copied from interface: PriorityQueue
      Enqueues a new element.
      Specified by:
      enqueue in interface PriorityQueue
      Parameters:
      o - the element to enqueue.

    • dequeue

      public java.lang.Object dequeue()
      Description copied from interface: PriorityQueue
      Dequeues the first element from the queue.
      Specified by:
      dequeue in interface PriorityQueue
      Returns:
      the dequeued element.

    • isEmpty

      public boolean isEmpty()
      Description copied from interface: PriorityQueue
      Checks whether this queue is empty.

      This default implementation checks whether PriorityQueue.size() is zero.

      Specified by:
      isEmpty in interface PriorityQueue
      Returns:
      true if this queue is empty.

    • size

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

    • first

      public java.lang.Object first()
      Description copied from interface: PriorityQueue
      Returns the first element of the queue.
      Specified by:
      first in interface PriorityQueue
      Returns:
      the first element.

    • last

      public java.lang.Object last()
      Description copied from interface: PriorityQueue
      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:
      last in interface PriorityQueue
      Returns:
      the last 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

    • comparator

      public java.util.Comparator<?> 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
      Returns:
      the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

    • clone

      public java.lang.Object clone()

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class java.lang.Object

    • equals

      public boolean equals​(java.lang.Object o)
      Overrides:
      equals in class java.lang.Object