structure
Class CircularList

java.lang.Object
  |
  +--structure.AbstractStructure
        |
        +--structure.AbstractList
              |
              +--structure.CircularList

All Implemented Interfaces:

List, Structure

Direct Known Subclasses:

AppendableList

public class CircularList

extends AbstractList

An implementation of lists using circularly linked elements, similar to that of java.util.LinkedList.

This class is an implementation of the List interface. Operations accessing or modifying either the head or the tail of the list execute in constant time. Circular lists are as space-efficient as singly linked lists, but tail-related operations are less costly.

Example usage: To place a copy of every unique parameter passed to a program into a CircularList, we would use the following:

 public static void main(String[] arguments)
 {
     CircularList argList = new CircularList();
     for (int i = 0; i < arguments.length; i++){
	   if (!argList.contains(arguments[i])){
	       argList.add(arguments[i]);
         }
    }
    System.out.println(argList);
 }
 

See Also:

SinglyLinkedList, DoublyLinkedList

Field Summary

protected int	count Number of elements within circular list.
protected SinglyLinkedListElement	tail A reference to tail of list.

Constructor Summary

CircularList()
Construct an empty circular list.

Method Summary

void	add(int i, java.lang.Object o) Insert value at location.
void	add(java.lang.Object value) Add an element to head of circular list.
void	addFirst(java.lang.Object value) Add an element to head of list.
void	addLast(java.lang.Object value) Add a value to tail of circular list.
void	clear() Remove elements of list.
boolean	contains(java.lang.Object value) Check if a list contains an element.
java.lang.Object	get(int i) Get value at location i.
java.lang.Object	getFirst() Determine if a list is empty.
java.lang.Object	getLast() Peek at last element of list.
protected SinglyLinkedListElement	getTail() Accessor method for tail field
int	indexOf(java.lang.Object value) Determine first location of a value in list.
boolean	isEmpty() Determine if a list is empty.
java.util.Iterator	iterator() Construct an iterator over elements of list.
int	lastIndexOf(java.lang.Object value) Determine last location of a value in list.
java.lang.Object	remove(int i) Remove and return value at location i.
java.lang.Object	remove(java.lang.Object value) Remove a value from a list.
java.lang.Object	removeFirst() Remove a value from head of list.
java.lang.Object	removeLast() Remove a value from tail of list.
java.lang.Object	set(int i, java.lang.Object o) Set value stored at location i to object o, returning old value.
int	size() Determine size of list.
java.lang.String	toString() Generate a string representation of list.

Methods inherited from class structure.AbstractList

get, remove

Methods inherited from class structure.AbstractStructure

elements, hashCode, values

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface structure.Structure

elements, values

Field Detail

tail

protected SinglyLinkedListElement tail

A reference to tail of list. tail points to head.

count

protected int count

Number of elements within circular list.

Constructor Detail

CircularList

public CircularList()

Construct an empty circular list.

Method Detail

add

public void add(java.lang.Object value)

Add an element to head of circular list.

Specified by:

add in interface List

Overrides:

add in class AbstractList

Parameters:

value - value to be added to list.

See Also:

AbstractList.addLast(java.lang.Object)

addFirst

public void addFirst(java.lang.Object value)

Add an element to head of list.

Specified by:

addFirst in interface List

Overrides:

addFirst in class AbstractList

Parameters:

value - value added to head of list.

addLast

public void addLast(java.lang.Object value)

Add a value to tail of circular list.

Specified by:

addLast in interface List

Overrides:

addLast in class AbstractList

Parameters:

value - value to be added.

getFirst

public java.lang.Object getFirst()

Determine if a list is empty.

Specified by:

getFirst in interface List

Overrides:

getFirst in class AbstractList

Returns:

True if there are no elements within list.

getLast

public java.lang.Object getLast()

Peek at last element of list.

Specified by:

getLast in interface List

Overrides:

getLast in class AbstractList

Returns:

value of last element of list.

removeFirst

public java.lang.Object removeFirst()

Remove a value from head of list.

Specified by:

removeFirst in interface List

Overrides:

removeFirst in class AbstractList

Returns:

value removed.

removeLast

public java.lang.Object removeLast()

Remove a value from tail of list.

Specified by:

removeLast in interface List

Overrides:

removeLast in class AbstractList

Returns:

value removed.

contains

public boolean contains(java.lang.Object value)

Check if a list contains an element.

Specified by:

contains in interface List

Overrides:

contains in class AbstractList

Parameters:

value - value sought.

Returns:

True iff value is within list.

remove

public java.lang.Object remove(java.lang.Object value)

Remove a value from a list.

Parameters:

value - value sought.

Returns:

value removed from list.

size

public int size()

Determine size of list.

Returns:

number of elements in list.

get

public java.lang.Object get(int i)

Get value at location i.

Parameters:

i - position of value to be retrieved.

Returns:

value retrieved from location i (returns null if i invalid)

getTail

protected SinglyLinkedListElement getTail()

Accessor method for tail field

set

public java.lang.Object set(int i,
                            java.lang.Object o)

Set value stored at location i to object o, returning old value.

Parameters:

i - location of entry to be changed.

o - new value

Returns:

former value of ith entry of list.

add

public void add(int i,
                java.lang.Object o)

Insert value at location.

Parameters:

i - index of this new value

o - value to be stored

remove

public java.lang.Object remove(int i)

Remove and return value at location i.

Parameters:

i - position of value to be retrieved.

Returns:

value retrieved from location i (returns null if i invalid)

indexOf

public int indexOf(java.lang.Object value)

Determine first location of a value in list.

Parameters:

value - value sought.

Returns:

index (0 is first element) of value, or -1

lastIndexOf

public int lastIndexOf(java.lang.Object value)

Determine last location of a value in list.

Parameters:

value - value sought.

Returns:

index (0 is first element) of value, or -1

iterator

public java.util.Iterator iterator()

Construct an iterator over elements of list. Elements are traversed from head to tail.

Returns:

iterator associated with list.

isEmpty

public boolean isEmpty()

Determine if a list is empty.

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class AbstractList

Returns:

True iff list is empty.

clear

public void clear()

Remove elements of list.

toString

public java.lang.String toString()

Generate a string representation of list.

Overrides:

toString in class java.lang.Object

Returns:

String representing list.