org.apache.commons.collections.list
Class TreeList

java.lang.Object
  |
  +--java.util.AbstractCollection
        |
        +--java.util.AbstractList
              |
              +--org.apache.commons.collections.list.TreeList

All Implemented Interfaces:

Collection, List

public class TreeList

extends AbstractList

A List implementation that is optimised for fast insertions and removals at any index in the list.

This list implementation utilises a tree structure internally to ensure that all insertions and removals are O(log n). This provides much faster performance than both an ArrayList and a LinkedList where elements are inserted and removed repeatedly from anywhere in the list.

The following relative performance statistics are indicative of this class:

              get  add  insert  iterate  remove
 TreeList       3    5       1       2       1
 ArrayList      1    1      40       1      40
 LinkedList  5800    1     350       2     325
 

ArrayList is a good general purpose list implementation. It is faster than TreeList for most operations except inserting and removing in the middle of the list. ArrayList also uses less memory as TreeList uses one object per entry.

LinkedList is rarely a good choice of implementation. TreeList is almost always a good replacement for it, although it does use sligtly more memory.

Since:

Commons Collections 3.1

Version:

$Revision: 1.3 $ $Date: 2004/05/26 21:56:05 $

Author:

Joerg Schmuecker, Stephen Colebourne

Field Summary

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

TreeList()
Constructs a new empty list.

TreeList(Collection coll)
Constructs a new empty list that copies the specified list.

Method Summary

void	add(int index, Object obj) Adds a new element to the list.
void	clear() Clears the list, removing all entries.
boolean	contains(Object object) Searches for the presence of an object in the list.
Object	get(int index) Gets the element at the specified index.
int	indexOf(Object object) Searches for the index of an object in the list.
Iterator	iterator() Gets an iterator over the list.
ListIterator	listIterator() Gets a ListIterator over the list.
ListIterator	listIterator(int fromIndex) Gets a ListIterator over the list.
Object	remove(int index) Removes the element at the specified index.
Object	set(int index, Object obj) Sets the element at the specified index.
int	size() Gets the current size of the list.
Object[]	toArray() Converts the list into an array.

Methods inherited from class java.util.AbstractList

add, addAll, equals, hashCode, lastIndexOf, removeRange, subList

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List

addAll, containsAll, isEmpty, remove, removeAll, retainAll, toArray

Constructor Detail

TreeList

public TreeList()

Constructs a new empty list.

TreeList

public TreeList(Collection coll)

Constructs a new empty list that copies the specified list.

Parameters:

coll - the collection to copy

Throws:

NullPointerException - if the collection is null

Method Detail

get

public Object get(int index)

Gets the element at the specified index.

Specified by:

get in interface List

Specified by:

get in class AbstractList

Parameters:

index - the index to retrieve

Returns:

the element at the specified index

size

public int size()

Gets the current size of the list.

Specified by:

size in interface List

Specified by:

size in class AbstractCollection

Returns:

the current size

iterator

public Iterator iterator()

Gets an iterator over the list.

Specified by:

iterator in interface List

Overrides:

iterator in class AbstractList

Returns:

an iterator over the list

listIterator

public ListIterator listIterator()

Gets a ListIterator over the list.

Specified by:

listIterator in interface List

Overrides:

listIterator in class AbstractList

Returns:

the new iterator

listIterator

public ListIterator listIterator(int fromIndex)

Gets a ListIterator over the list.

Specified by:

listIterator in interface List

Overrides:

listIterator in class AbstractList

Parameters:

fromIndex - the index to start from

Returns:

the new iterator

indexOf

public int indexOf(Object object)

Searches for the index of an object in the list.

Specified by:

indexOf in interface List

Overrides:

indexOf in class AbstractList

Returns:

the index of the object, -1 if not found

contains

public boolean contains(Object object)

Searches for the presence of an object in the list.

Specified by:

contains in interface List

Overrides:

contains in class AbstractCollection

Returns:

true if the object is found

toArray

public Object[] toArray()

Converts the list into an array.

Specified by:

toArray in interface List

Overrides:

toArray in class AbstractCollection

Returns:

the list as an array

add

public void add(int index,
                Object obj)

Adds a new element to the list.

Specified by:

add in interface List

Overrides:

add in class AbstractList

Parameters:

index - the index to add before

obj - the element to add

set

public Object set(int index,
                  Object obj)

Sets the element at the specified index.

Specified by:

set in interface List

Overrides:

set in class AbstractList

Parameters:

index - the index to set

obj - the object to store at the specified index

Returns:

the previous object at that index

Throws:

IndexOutOfBoundsException - if the index is invalid

remove

public Object remove(int index)

Removes the element at the specified index.

Specified by:

remove in interface List

Overrides:

remove in class AbstractList

Parameters:

index - the index to remove

Returns:

the previous object at that index

clear

public void clear()

Clears the list, removing all entries.

Specified by:

clear in interface List

Overrides:

clear in class AbstractList