Apache Commons Collections 4.4 · org.apache.commons.collections4.list.TreeList

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 slightly more memory.

Modifier and Type	Class and Description
pack-priv static class	TreeList.AVLNode<E> Implements an AVLNode which keeps the offset updated.
pack-priv static class	TreeList.TreeListIterator<E> A list iterator over the linked list.

Modifier and Type	Field and Description
private TreeList.AVLNode<E>	root The root node in the AVL tree
private int	size The current size of the list

Access	Constructor and Description
public	TreeList() Constructs a new empty list.
public	TreeList(final Collection<? extends E> the collection to copy coll) Constructs a new empty list that copies the specified collection.

Method Summary

Modifier and Type	Method and Description
public void	add(final int the index to add before index, final E the element to add obj) Overrides java.util.AbstractList.add. Implements java.util.List.add. Adds a new element to the list.
public boolean	Returns: `true` if this list changed as a result of the call addAll(final Collection<? extends E> the collection to be added to this list c) Overrides java.util.AbstractCollection.addAll. Implements java.util.List.addAll, java.util.Collection.addAll. Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's Iterator.
private void	checkInterval(final int the index to check index, final int the first allowed index startIndex, final int the last allowed index endIndex) Checks whether the index is valid.
public void	clear() Overrides java.util.AbstractList.clear. Implements java.util.List.clear, java.util.Collection.clear. Clears the list, removing all entries.
public boolean	Returns: true if the object is found contains(final Object the object to check object) Overrides java.util.AbstractCollection.contains. Implements java.util.List.contains, java.util.Collection.contains. Searches for the presence of an object in the list.
public E	Returns: the element at the specified index get(final int the index to retrieve index) Implements abstract java.util.AbstractList.get. Implements java.util.List.get. Gets the element at the specified index.
public int	Returns: the index of the object, -1 if not found indexOf(final Object the object to search object) Overrides java.util.AbstractList.indexOf. Implements java.util.List.indexOf. Searches for the index of an object in the list.
public Iterator<E>	Returns: an iterator over the list iterator() Overrides java.util.AbstractList.iterator. Implements java.util.List.iterator, java.util.Collection.iterator. Gets an iterator over the list.
public ListIterator<E>	Returns: the new iterator listIterator() Overrides java.util.AbstractList.listIterator. Implements java.util.List.listIterator. Gets a ListIterator over the list.
public ListIterator<E>	Returns: the new iterator listIterator(final int the index to start from fromIndex) Overrides java.util.AbstractList.listIterator. Implements java.util.List.listIterator. Gets a ListIterator over the list.
public E	Returns: the previous object at that index remove(final int the index to remove index) Overrides java.util.AbstractList.remove. Implements java.util.List.remove. Removes the element at the specified index.
public E	Returns: the previous object at that index set(final int the index to set index, final E the object to store at the specified index obj) Overrides java.util.AbstractList.set. Implements java.util.List.set. Sets the element at the specified index.
public int	Returns: the current size size() Implements abstract java.util.AbstractCollection.size. Implements java.util.List.size, java.util.Collection.size. Gets the current size of the list.
public Object[]	Returns: the list as an array toArray() Overrides java.util.AbstractCollection.toArray. Implements java.util.List.toArray, java.util.Collection.toArray. Converts the list into an array.

Inherited from java.util.AbstractList:: add addAll equals hashCode lastIndexOf removeRange subList

public Class TreeList<E>

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary