LinkedQueue

java.lang.Object
- AQueue<E>
- - LinkedQueue<E>

Type Parameters:

E - the type of elements held in this collection

All Implemented Interfaces:

IQueue<E>
```
public class LinkedQueue<E>
extends AQueue<E>
implements IQueue<E>
```
LinkedQueue is a FIFO (First In First Out) data structure that stores its elements in non-contiguous chunks of memory that reference one another, forming a linked list.
The individual links in a doubly linked list have references to both the preceding and succeeding links in the list. A link in a singly linked list only has a reference to the next link in the list.
A singly linked list is fine for our purposes here. It supports efficient removal of the head, and (if you keep a reference to the tail) it supports efficient adding of new elements to the tail.
created by cspfrederick and garethhalladay Fall17
inspired by Chris Wilcox

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

(package private) class LinkedQueue.Link
Underlying data structure to create a singly linked list.

Nested Classes
Modifier and Type	Class and Description
`(package private) class`	`LinkedQueue.Link` Underlying data structure to create a singly linked list.

Constructor Summary

Constructors
Constructor and Description

LinkedQueue(int maxSize)
Creates a queue that will allow up to maxSize elements.

Constructors
Constructor and Description
`LinkedQueue(int maxSize)` Creates a queue that will allow up to `maxSize` elements.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears the queue.
`boolean`	`contains(java.lang.Object o)` Returns true if this queue contains the specified element.
`static void`	`main(java.lang.String[] args)`
`boolean`	`offer(E e)` Adds an element to the queue.
`E`	`peek()` Returns (but does not remove) the head element in the queue.
`E`	`poll()` Removes and returns the oldest element from the queue.
`int`	`size()` Returns the number of elements in this queue.

Methods inherited from class AQueue
add, element, isEmpty, remove

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface IQueue
add, element, isEmpty, remove, toString

- Constructor Detail
  - LinkedQueue
```
LinkedQueue(int maxSize)
```
    Creates a queue that will allow up to maxSize elements.
    
    Parameters:
    
    maxSize - The maximum size of the queue
    
    See Also:
    
    maxCount
- Method Detail
  - offer
```
public boolean offer(E e)
```
    Adds an element to the queue. If the queue is full, do not modify it, and return false.
    If the queue was empty, you will need to assign head and tail to a new Link instance and set count to one.
    Otherwise, create a new Link, and link it in to the end of the queue. Make sure to set tail to reference the new Link, and increment count.
    
    Specified by:
    
    offer in interface IQueue<E>
    
    Parameters:
    
    e - the element to be added to the queue
    
    Returns:
    
    true if the element was added successfully, false otherwise.
  - poll
```
public E poll()
```
    Removes and returns the oldest element from the queue. Returns null if empty.
    1. Decrement count
    2. Store the value that is currently in the head node in a local variable
    3. Assign head to the second Link in the queue, effectively removing the head
    4. If head is now null, then set head and tail to null, because that was the last item in the queue, and it is now empty
    5. Return the original head value
    Specified by:
    
    poll in interface IQueue<E>
    
    Returns:
    
    the oldest element from the queue or null if empty
  - peek
```
public E peek()
```
    Returns (but does not remove) the head element in the queue. Returns null if the queue is empty.
    
    Specified by:
    
    peek in interface IQueue<E>
    
    Returns:
    
    the oldest element from the queue or null if empty
  - size
```
public int size()
```
    Description copied from interface: IQueue
    
    Returns the number of elements in this queue.
    
    Specified by:
    
    size in interface IQueue<E>
    
    Returns:
    
    the number of elements in the queue
  - clear
```
public void clear()
```
    Clears the queue. This should set the head and tail back to null and the count back to 0.
    
    Specified by:
    
    clear in interface IQueue<E>
  - contains
```
public boolean contains(java.lang.Object o)
```
    Description copied from interface: IQueue
    
    Returns true if this queue contains the specified element. More formally, returns true if and only if this queue contains at least one element e such that o.equals(e).
    
    Specified by:
    
    contains in interface IQueue<E>
    
    Parameters:
    
    o - object to be checked for containment in this queue
    
    Returns:
    
    true if this queue contains the specified element, false otherwise
  - main
```
public static void main(java.lang.String[] args)
```

CSU CS165

Class LinkedQueue<E>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class AQueue

Methods inherited from class java.lang.Object

Methods inherited from interface IQueue

Constructor Detail

LinkedQueue

Method Detail

offer

poll

peek

size

clear

contains

main

CSU CS165