org.apache.commons.math3.geometry.partitioning.utilities
Class AVLTree<T extends Comparable<T>>

java.lang.Object
  extended by org.apache.commons.math3.geometry.partitioning.utilities.AVLTree<T>
Type Parameters:
T - the type of the elements

public class AVLTree<T extends Comparable<T>>
extends Object

This class implements AVL trees.

The purpose of this class is to sort elements while allowing duplicate elements (i.e. such that a.equals(b) is true). The SortedSet interface does not allow this, so a specific class is needed. Null elements are not allowed.

Since the equals method is not sufficient to differentiate elements, the delete method is implemented using the equality operator.

In order to clearly mark the methods provided here do not have the same semantics as the ones specified in the SortedSet interface, different names are used (add has been replaced by insert and remove has been replaced by delete).

This class is based on the C implementation Georg Kraml has put in the public domain. Unfortunately, his page seems not to exist any more.

Since:
3.0
Version:
$Id: AVLTree.java 1416643 2012-12-03 19:37:14Z tn $

Nested Class Summary
 class AVLTree.Node
          This class implements AVL trees nodes.
 
Constructor Summary
AVLTree()
          Build an empty tree.
 
Method Summary
 boolean delete(T element)
          Delete an element from the tree.
 AVLTree.Node getLargest()
          Get the node whose element is the largest one in the tree.
 AVLTree.Node getNotLarger(T reference)
          Get the node whose element is not larger than the reference object.
 AVLTree.Node getNotSmaller(T reference)
          Get the node whose element is not smaller than the reference object.
 AVLTree.Node getSmallest()
          Get the node whose element is the smallest one in the tree.
 void insert(T element)
          Insert an element in the tree.
 boolean isEmpty()
          Check if the tree is empty.
 int size()
          Get the number of elements of the tree.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AVLTree

public AVLTree()
Build an empty tree.

Method Detail

insert

public void insert(T element)
Insert an element in the tree.

Parameters:
element - element to insert (silently ignored if null)

delete

public boolean delete(T element)
Delete an element from the tree.

The element is deleted only if there is a node n containing exactly the element instance specified, i.e. for which n.getElement() == element. This is purposely different from the specification of the java.util.Set remove method (in fact, this is the reason why a specific class has been developed).

Parameters:
element - element to delete (silently ignored if null)
Returns:
true if the element was deleted from the tree

isEmpty

public boolean isEmpty()
Check if the tree is empty.

Returns:
true if the tree is empty

size

public int size()
Get the number of elements of the tree.

Returns:
number of elements contained in the tree

getSmallest

public AVLTree.Node getSmallest()
Get the node whose element is the smallest one in the tree.

Returns:
the tree node containing the smallest element in the tree or null if the tree is empty
See Also:
getLargest(), getNotSmaller(T), getNotLarger(T), AVLTree.Node.getPrevious(), AVLTree.Node.getNext()

getLargest

public AVLTree.Node getLargest()
Get the node whose element is the largest one in the tree.

Returns:
the tree node containing the largest element in the tree or null if the tree is empty
See Also:
getSmallest(), getNotSmaller(T), getNotLarger(T), AVLTree.Node.getPrevious(), AVLTree.Node.getNext()

getNotSmaller

public AVLTree.Node getNotSmaller(T reference)
Get the node whose element is not smaller than the reference object.

Parameters:
reference - reference object (may not be in the tree)
Returns:
the tree node containing the smallest element not smaller than the reference object or null if either the tree is empty or all its elements are smaller than the reference object
See Also:
getSmallest(), getLargest(), getNotLarger(T), AVLTree.Node.getPrevious(), AVLTree.Node.getNext()

getNotLarger

public AVLTree.Node getNotLarger(T reference)
Get the node whose element is not larger than the reference object.

Parameters:
reference - reference object (may not be in the tree)
Returns:
the tree node containing the largest element not larger than the reference object (in which case the node is guaranteed not to be empty) or null if either the tree is empty or all its elements are larger than the reference object
See Also:
getSmallest(), getLargest(), getNotSmaller(T), AVLTree.Node.getPrevious(), AVLTree.Node.getNext()


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