inf.util
Class ArrayOfHashedListsIntPriorityQueue<E>

java.lang.Object
  inf.util.ArrayOfHashedListsIntPriorityQueue<E>

Type Parameters:

E - the element type for elements queued

All Implemented Interfaces:

IntPriorityQueue<E>, PriorityQueue<E,java.lang.Integer>, java.lang.Iterable<E>

public class ArrayOfHashedListsIntPriorityQueue<E>
extends java.lang.Object
implements IntPriorityQueue<E>

This class represents a priority queue, that is a queue in which elements can be held and from which they can be retrieved by priority. For this purpose, each object has a priority associated with it that determines when in relation to the other elements in the queue this element should be retrieved. Priorities are ints here. Note, however, that priority values must not be negative.

The implementation of this priority queue is achieved by maintaining the elements in an array for low priorities and a sorted tree for higher values. The order is determined by the priority and each array entry or tree node contains a HashedList of all the nodes with the same priority. In this way a reasonably efficient execution of all the operations provided can be guaranteed even for very long queues. The removal of elements from this queue and the contains-test with a given priority are supported. However, it also means that queued elements must not be null and no two equal elements can be stored at the same priority.

Author:

Gerhard Wickler

Nested Class Summary

(package private) class

ArrayOfHashedListsIntPriorityQueue.ArrayOfHashedListsIntPriorityQueueIterator<T> This class represents an iterator for the elements in an ArrayOfListsIntPriorityQueue.

Field Summary

protected HashedList<E>[]	pArray the data structure that contains an array of lists of nodes
protected IntKeyTreeMap<HashedList<E>>	pTree the data structure that contains a tree of lists of nodes

Constructor Summary

ArrayOfHashedListsIntPriorityQueue()
This constructor creates an empty PriorityQueue.

ArrayOfHashedListsIntPriorityQueue(int maxArrayPriority)
This constructor creates an empty PriorityQueue where elements up to the given priority are stored in an array for quicker access.

Method Summary

void	addElementFirst(E element, int priority) This function adds the given element at the given priority to this priority queue.
void	addElementFirst(E element, java.lang.Integer priority) This function adds the given element at the given priority to this priority queue.
void	addElementLast(E element, int priority) This function adds the given element at the given priority to this priority queue.
void	addElementLast(E element, java.lang.Integer priority) This function adds the given element at the given priority to this priority queue.
protected ArrayOfHashedListsIntPriorityQueue<E>	clone() This class does not support cloning and an Exception will be thrown if this method is called.
boolean	containsElementAt(E element, int priority) This function tests whether the given element is currently in this queue at the given priority.
boolean	containsElementAt(E element, java.lang.Integer priority) This function tests whether the given element is currently in this queue at the given priority.
boolean	equals(java.lang.Object obj) This class does not support equality testing and an exception will be thrown if this method is called.
E	getHighestFirst() This function returns the element in this priority queue that has the highest priority.
E	getHighestLast() This function returns the element in this priority queue that has the highest priority.
E	getLowestFirst() This function returns the element in this priority queue that has the lowest priority.
E	getLowestLast() This function returns the element in this priority queue that has the lowest priority.
int	hashCode() This class does not support hashing and an exception will be thrown if this method is called.
boolean	isEmpty() This function tests whether this PriorityQueue is empty.
java.util.Iterator<E>	iterator() This function returns an Iterator for this priority queue.
int	length() This function returns the size of this priority queue.
boolean	removeElementAt(E element, int priority) This function attempts to remove the given element at the given priority from this priority queue.
boolean	removeElementAt(E element, java.lang.Integer priority) This function attempts to remove the given element at the given priority from this priority queue.
E	removeHighestFirst() This function removes and returns the element in this priority queue that has the highest priority.
E	removeHighestLast() This function removes and returns the element in this priority queue that has the highest priority.
E	removeLowestFirst() This function removes and returns the element in this priority queue that has the lowest priority.
E	removeLowestLast() This function removes and returns the element in this priority queue that has the lowest priority.
java.lang.String	toString() This function creates the printable string representation of this priority queue.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

pArray

protected HashedList<E>[] pArray

the data structure that contains an array of lists of nodes

pTree

protected IntKeyTreeMap<HashedList<E>> pTree

the data structure that contains a tree of lists of nodes

Constructor Detail

ArrayOfHashedListsIntPriorityQueue

public ArrayOfHashedListsIntPriorityQueue()

This constructor creates an empty PriorityQueue.

ArrayOfHashedListsIntPriorityQueue

public ArrayOfHashedListsIntPriorityQueue(int maxArrayPriority)

This constructor creates an empty PriorityQueue where elements up to the given priority are stored in an array for quicker access. Elements with higher priority are stored in a tree.

Parameters:

maxArrayPriority - the highest priority value stored in the array

Method Detail

clone

protected ArrayOfHashedListsIntPriorityQueue<E> clone()
                                               throws java.lang.CloneNotSupportedException

This class does not support cloning and an Exception will be thrown if this method is called.

Overrides:

clone in class java.lang.Object

Returns:

nothing

Throws:

java.lang.CloneNotSupportedException - will be thrown

addElementFirst

public void addElementFirst(E element,
                            java.lang.Integer priority)

This function adds the given element at the given priority to this priority queue. Note that the priority must not be negative, the queued element must not be null and no two equal elements can be stored at the same priority. If there are already elements queued at this priority, the new element will be queued at the front.

Specified by:

addElementFirst in interface PriorityQueue<E,java.lang.Integer>

Parameters:

element - the element to be added to this IntPriorityQueue

priority - the priority with which the element is to be queued

addElementLast

public void addElementLast(E element,
                           java.lang.Integer priority)

This function adds the given element at the given priority to this priority queue. Note that the priority must not be negative, the queued element must not be null and no two equal elements can be stored at the same priority. If there are already elements queued at this priority, the new element will be queued at the end.

Specified by:

addElementLast in interface PriorityQueue<E,java.lang.Integer>

Parameters:

element - the element to be added to this IntPriorityQueue

priority - the priority with which the element is to be queued

isEmpty

public boolean isEmpty()

This function tests whether this PriorityQueue is empty.

Specified by:

isEmpty in interface PriorityQueue<E,java.lang.Integer>

Returns:

true if and only if this PriorityQueue contains no elements

length

public int length()

This function returns the size of this priority queue.

Specified by:

length in interface PriorityQueue<E,java.lang.Integer>

Returns:

the number of elements contained in this PriorityQueue

getLowestFirst

public E getLowestFirst()
                 throws java.util.NoSuchElementException

This function returns the element in this priority queue that has the lowest priority. If there are several elements queued at that priority, the element at the front of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

getLowestFirst in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the lowest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

getLowestLast

public E getLowestLast()
                throws java.util.NoSuchElementException

This function returns the element in this priority queue that has the lowest priority. If there are several elements queued at that priority, the element at the end of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

getLowestLast in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the lowest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

getHighestFirst

public E getHighestFirst()
                  throws java.util.NoSuchElementException

This function returns the element in this priority queue that has the highest priority. If there are several elements queued at that priority, the element at the front of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

getHighestFirst in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

getHighestLast

public E getHighestLast()
                 throws java.util.NoSuchElementException

This function returns the element in this priority queue that has the highest priority. If there are several elements queued at that priority, the element at the end of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

getHighestLast in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

containsElementAt

public boolean containsElementAt(E element,
                                 java.lang.Integer priority)

This function tests whether the given element is currently in this queue at the given priority.

Specified by:

containsElementAt in interface PriorityQueue<E,java.lang.Integer>

Parameters:

element - element to be tested for

priority - the priority at which it should be queued

Returns:

boolean whether it is indeed in the queue

removeLowestFirst

public E removeLowestFirst()
                    throws java.util.NoSuchElementException

This function removes and returns the element in this priority queue that has the lowest priority. If there are several elements queued at that priority, the element at the front of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

removeLowestFirst in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

removeLowestLast

public E removeLowestLast()
                   throws java.util.NoSuchElementException

This function removes and returns the element in this priority queue that has the lowest priority. If there are several elements queued at that priority, the element at the end of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

removeLowestLast in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

removeHighestFirst

public E removeHighestFirst()
                     throws java.util.NoSuchElementException

This function removes and returns the element in this priority queue that has the highest priority. If there are several elements queued at that priority, the element at the front of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

removeHighestFirst in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

removeHighestLast

public E removeHighestLast()
                    throws java.util.NoSuchElementException

This function removes and returns the element in this priority queue that has the highest priority. If there are several elements queued at that priority, the element at the end of the list is retrieved. An exception is thrown if there is no such element, i.e. if this priority queue is empty.

Specified by:

removeHighestLast in interface PriorityQueue<E,java.lang.Integer>

Returns:

the element that has the highest priority in this PriorityQueue

Throws:

java.util.NoSuchElementException - if this PriorityQueue is empty

removeElementAt

public boolean removeElementAt(E element,
                               java.lang.Integer priority)

This function attempts to remove the given element at the given priority from this priority queue. Whether the removal was successful is returned.

Specified by:

removeElementAt in interface PriorityQueue<E,java.lang.Integer>

Parameters:

element - the element to be removed from this PriorityQueue

priority - the priority at which the element is queued

Returns:

true if and only if the object was indeed removed from the queue

addElementFirst

public void addElementFirst(E element,
                            int priority)

This function adds the given element at the given priority to this priority queue. Note that the priority must not be negative, the queued element must not be null and no two equal elements can be stored at the same priority. If there are already elements queued at this priority, the new element will be queued at the front.

Specified by:

addElementFirst in interface IntPriorityQueue<E>

Parameters:

element - the element to be added to this IntPriorityQueue

priority - the priority with which the element is to be queued

addElementLast

public void addElementLast(E element,
                           int priority)

This function adds the given element at the given priority to this priority queue. Note that the priority must not be negative, the queued element must not be null and no two equal elements can be stored at the same priority. If there are already elements queued at this priority, the new element will be queued at the end.

Specified by:

addElementLast in interface IntPriorityQueue<E>

Parameters:

element - the element to be added to this IntPriorityQueue

priority - the priority with which the element is to be queued

containsElementAt

public boolean containsElementAt(E element,
                                 int priority)

This function tests whether the given element is currently in this queue at the given priority.

Specified by:

containsElementAt in interface IntPriorityQueue<E>

Parameters:

element - element to be tested for

priority - the priority at which it should be queued

Returns:

boolean whether it is indeed in the queue

removeElementAt

public boolean removeElementAt(E element,
                               int priority)

This function attempts to remove the given element at the given priority from this priority queue. Whether the removal was successful is returned.

Specified by:

removeElementAt in interface IntPriorityQueue<E>

Parameters:

element - the element to be removed from this PriorityQueue

priority - the priority at which the element is queued

Returns:

true if and only if the object was indeed removed from the queue

iterator

public java.util.Iterator<E> iterator()

This function returns an Iterator for this priority queue.

Specified by:

iterator in interface java.lang.Iterable<E>

Returns:

an Iterator for this PriorityQueue

equals

public boolean equals(java.lang.Object obj)
               throws java.lang.UnsupportedOperationException

This class does not support equality testing and an exception will be thrown if this method is called.

Overrides:

equals in class java.lang.Object

Parameters:

obj - the Object this should be compared to

Returns:

nothing

Throws:

java.lang.UnsupportedOperationException - will be thrown

hashCode

public int hashCode()
             throws java.lang.UnsupportedOperationException

This class does not support hashing and an exception will be thrown if this method is called.

Overrides:

hashCode in class java.lang.Object

Returns:

nothing

Throws:

java.lang.UnsupportedOperationException - will be thrown

toString

public java.lang.String toString()

This function creates the printable string representation of this priority queue.

Overrides:

toString in class java.lang.Object

Returns:

the String representing this PriorityQueue