structure
Class BinarySearchTree

java.lang.Object
  |
  +--structure.AbstractStructure
        |
        +--structure.BinarySearchTree

All Implemented Interfaces:

OrderedStructure, Structure

Direct Known Subclasses:

SplayTree

public class BinarySearchTree

extends AbstractStructure

implements OrderedStructure

A binary search tree structure. This structure maintains data in an ordered tree. It does not keep the tree balanced, so performance may degrade if the tree height is not optimal.

Example usage:

To create a Binary search tree containing the months of the year and to print out this tree as it grows we could use the following.

 public static void main(String[] argv){
     BinarySearchTree test = new BinarySearchTree();
       
     //declare an array of months
     String[] months = new String[]{"March", "May", "November", "August", 
      			      "April", "January", "December", "July",
				      "February", "June", "October", "September"};
      
     //add the months to the tree and print out the tree as it grows
     for(int i=0; i < months.length; i++){
        test.add(months[i]);
        System.out.println("Adding: " + months[i] + "\n" +test.treeString());
      }
  }
 

See Also:

SplayTree, BinaryTree

Field Summary

protected int	count The number of nodes in the tree
protected Comparator	ordering The ordering used on this search tree.
protected BinaryTree	root A reference to the root of the tree

Constructor Summary

BinarySearchTree()
Constructs a binary search tree with no data

BinarySearchTree(Comparator alternateOrder)
Constructs a binary search tree with no data

Method Summary

void	add(Object value) Add a (possibly duplicate) value to binary search tree
void	clear() Removes all data from the binary search tree
boolean	contains(Object value) Determines if the binary search tree contains a value
Object	get(Object value) Returns reference to value found within three.
int	hashCode() Returns the hashCode of the value stored by this object.
boolean	isEmpty() Checks for an empty binary search tree
Iterator	iterator() Returns an iterator over the binary search tree.
protected BinaryTree	locate(BinaryTree root, Object value)
protected BinaryTree	predecessor(BinaryTree root)
Object	remove(Object value) Remove an value "equals to" the indicated value.
protected BinaryTree	removeTop(BinaryTree topNode) Removes the top node of the tree rooted, performs the necissary rotations to reconnect the tree.
int	size() Determines the number of data values within the tree
protected BinaryTree	successor(BinaryTree root)
String	toString() Returns a string representing tree
String	treeString() Returns a (possibly long) string representing tree.

Methods inherited from class structure.AbstractStructure

elements, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface structure.Structure

elements, values

Field Detail

root

protected BinaryTree root

A reference to the root of the tree

count

protected int count

The number of nodes in the tree

ordering

protected Comparator ordering

The ordering used on this search tree.

Constructor Detail

BinarySearchTree

public BinarySearchTree()

Constructs a binary search tree with no data

BinarySearchTree

public BinarySearchTree(Comparator alternateOrder)

Constructs a binary search tree with no data

Method Detail

isEmpty

public boolean isEmpty()

Checks for an empty binary search tree

Specified by:

isEmpty in interface Structure

Overrides:

isEmpty in class AbstractStructure

Postcondition:

Returns true iff the binary search tree is empty

Returns:

True iff the tree contains no data

clear

public void clear()

Removes all data from the binary search tree

Specified by:

clear in interface Structure

Postcondition:

Removes all elements from binary search tree

size

public int size()

Determines the number of data values within the tree

Specified by:

size in interface Structure

Postcondition:

Returns the number of elements in binary search tree

Returns:

The number of nodes in the binary search tree

locate

protected BinaryTree locate(BinaryTree root,
                            Object value)

Precondition:

root and value are non-null

Postcondition:

returned: 1 - existing tree node with the desired value, or 2 - the node to which value should be added

predecessor

protected BinaryTree predecessor(BinaryTree root)

successor

protected BinaryTree successor(BinaryTree root)

add

public void add(Object value)

Add a (possibly duplicate) value to binary search tree

Specified by:

add in interface Structure

Parameters:

val - A reference to non-null object

Postcondition:

Adds a value to binary search tree

contains

public boolean contains(Object value)

Determines if the binary search tree contains a value

Specified by:

contains in interface Structure

Overrides:

contains in class AbstractStructure

Parameters:

val - The value sought. Should be non-null

Postcondition:

Returns true iff val is a value found within the tree

Returns:

True iff the tree contains a value "equals to" sought value

get

public Object get(Object value)

Returns reference to value found within three. This method can be potentially dangerous if returned value is modified: if modification would change the relation of value to others within the tree, the consistency of the structure is lost Don't modify returned value

Parameters:

val - Value sought from within tree

Postcondition:

Returns object found in tree, or null

Returns:

A value "equals to" value sought; otherwise null

remove

public Object remove(Object value)

Remove an value "equals to" the indicated value. Only one value is removed, and no guarantee is made concerning which of duplicate values are removed. Value returned is no longer part of the structure

Specified by:

remove in interface Structure

Parameters:

val - Value sought to be removed from tree

Postcondition:

Removes one instance of val, if found

Returns:

Actual value removed from tree

removeTop

protected BinaryTree removeTop(BinaryTree topNode)

Removes the top node of the tree rooted, performs the necissary rotations to reconnect the tree.

Parameters:

topNode - Contains the value we want to remove

Precondition:

topNode contains the value we want to remove

Postcondition:

We return an binary tree rooted with the predecessor of topnode.

Returns:

The root of a new binary tree containing all of topNodes descendents and rooted at topNode's predecessor

iterator

public Iterator iterator()

Returns an iterator over the binary search tree. Iterator should not be used if tree is modified, as behavior may be unpredicatable Traverses elements using in-order traversal order

Specified by:

iterator in interface Structure

Postcondition:

Returns iterator to traverse BST

Returns:

An iterator over binary search tree

hashCode

public int hashCode()

Returns the hashCode of the value stored by this object.

Overrides:

hashCode in class AbstractStructure

Returns:

The hashCode of the value stored by this object.

treeString

public String treeString()

Returns a (possibly long) string representing tree. Differs from toString() in that toString() outputs a single line representation of the contents of the tree. treeString, however, prints out a graphical representations of the tree's structure.

Postcondition:

Generates a string representation of the AVLST

Returns:

String representation of tree

toString

public String toString()

Returns a string representing tree

Overrides:

toString in class Object

Postcondition:

Generates a string representation of the BST

Returns:

String representation of tree