structure
Interface Queue<ELTTYPE>

All Superinterfaces:

java.lang.Iterable<ELTTYPE>, Linear<ELTTYPE>, Structure<ELTTYPE>

All Known Implementing Classes:

AbstractQueue, QueueArray, QueueList, QueueVector

public interface Queue<ELTTYPE>
extends Linear<ELTTYPE>

Interface describing a first-in, first-out structure. Values are added at the tail, and removed from the head. Queues are typically used to process values in the order that they appear and to store the state of a buffered object. The structure package provides several implementations of the Queue interface, each of which has its particular strengths and weaknesses.

Example usage:

To compute the sum of the unicode value of every character in the standard input we could use the following:

 public static void main(String[] arguments)
 {
     Queue q = new QueueList();
     int unicodeSum = 0;

     if(arguments.length > 0){
         for(int i=0; i < arguments.length; i++){
               for(int j=0; j < arguments[i].length(); j++){
                   q.enqueue(new Character(arguments[i].charAt(j)));
               }
           }
     }

     while(!q.empty()){
          char c = ((Character)q.dequeue()).charValue();
          unicodeSum+=Character.getNumericValue(c);
     }

     System.out.println("Total Value: " + unicodeSum);
 }
 

See Also:

Stack, AbstractQueue, QueueArray, QueueVector, QueueList

Method Summary

void	add(ELTTYPE value) Add a value to the tail of the queue.
ELTTYPE	dequeue() Remove a value from the head of the queue.
boolean	empty() Returns true iff the queue is empty.
void	enqueue(ELTTYPE value) Add a value to the tail of the queue.
ELTTYPE	get() Fetch the value at the head of the queue.
ELTTYPE	getFirst() Fetch the value at the head of the queue.
ELTTYPE	peek() Fetch the value at the head of the queue.
ELTTYPE	remove() Remove a value form the head of the queue.
int	size() Returns the number of elements in the queue.

Methods inherited from interface structure.Structure

clear, contains, elements, isEmpty, iterator, remove, values

Method Detail

add

void add(ELTTYPE value)

Add a value to the tail of the queue.

Specified by:

add in interface Linear<ELTTYPE>

Specified by:

add in interface Structure<ELTTYPE>

Parameters:

value - The value added.

See Also:

enqueue(ELTTYPE)

Post:

the value is added to the tail of the structure

enqueue

void enqueue(ELTTYPE value)

Add a value to the tail of the queue.

Parameters:

value - The value to be added.

Post:

the value is added to the tail of the structure

remove

ELTTYPE remove()

Remove a value form the head of the queue.

Specified by:

remove in interface Linear<ELTTYPE>

Returns:

The value actually removed.

See Also:

dequeue()

Pre:

the queue is not empty

Post:

the head of the queue is removed and returned

dequeue

ELTTYPE dequeue()

Remove a value from the head of the queue.

Returns:

The value removed from the queue.

Pre:

the queue is not empty

Post:

the head of the queue is removed and returned

getFirst

ELTTYPE getFirst()

Fetch the value at the head of the queue.

Returns:

Reference to the first value of the queue.

Pre:

the queue is not empty

Post:

the element at the head of the queue is returned

get

ELTTYPE get()

Fetch the value at the head of the queue.

Specified by:

get in interface Linear<ELTTYPE>

Returns:

Reference to the first value of the queue.

Pre:

the queue is not empty

Post:

the element at the head of the queue is returned

peek

ELTTYPE peek()

Fetch the value at the head of the queue.

Returns:

Reference to the first value of the queue.

Pre:

the queue is not empty

Post:

the element at the head of the queue is returned

empty

boolean empty()

Returns true iff the queue is empty. Provided for compatibility with java.util.Vector.empty.

Specified by:

empty in interface Linear<ELTTYPE>

Returns:

True iff the queue is empty.

Post:

returns true if and only if the queue is empty

size

int size()

Returns the number of elements in the queue.

Specified by:

size in interface Linear<ELTTYPE>

Specified by:

size in interface Structure<ELTTYPE>

Returns:

number of elements in queue.

Post:

returns the number of elements in the queue