com.icl.saxon.sort

Class BinaryTree


public class BinaryTree
extends Object

A Binary Tree used for sorting. Similar to the java.util.Dictionary interface except (a) that the keys must be Strings rather than general Objects (b) the results are returned as a Vector, not an Enumeration.

The methods getKeys() and getValues() return values in ascending order of key. The keys are compared using a default Collator which sorts in alphabetical order with intelligent handling of case and accents.

Note that duplicate keys are not allowed: a new entry silently overwrites any previous entry with the same key. If you want to use dulicate keys, append a unique value (for example, a random number) to each one.

Version:
9 July 1999: now returns a Vector rather than an Enumeration
Author:
Michael H. Kay

Constructor Summary

BinaryTree()

Method Summary

Object
get(Object key)
get(String) returns the value corresponding to a given key, if any
Vector
getKeys()
getKeys() returns the keys in the tree in sorted order.
Vector
getValues()
getValues() returns the values in the tree in sorted order.
boolean
isEmpty()
isEmpty() Tests if this binary tree contains no keys.
static void
main(args[] )
Object
put(Object key, Object value)
put(Object, Object) puts a new entry in the tree, overwriting any previous entry with the same key.
Object
remove(Object key)
remove(Object) removes the key (and its corresponding value) from this Binary Tree.
void
setAscending(boolean ascending)
Set order.
void
setComparer(Comparer c)
Set the Comparer to be used for the keys in this tree.
void
setDuplicatesAllowed(boolean allow)
Define whether duplicate keys are allowed or not.
int
size()
size()

Constructor Details

BinaryTree

public BinaryTree()

Method Details

get

public Object get(Object key)
get(String) returns the value corresponding to a given key, if any
Parameters:
key - The key value being sought
Returns:
the value to which the key is mapped in this binary tree, or null if there is no entry with this key

getKeys

public Vector getKeys()
getKeys() returns the keys in the tree in sorted order.
Returns:
an Vector containing the keys in this BinaryTree (in key order).

getValues

public Vector getValues()
getValues() returns the values in the tree in sorted order.
Returns:
an Vector containing the values in this BinaryTree (in key order).

isEmpty

public boolean isEmpty()
isEmpty() Tests if this binary tree contains no keys.
Returns:
true if there are no entries in the tree

main

public static void main(args[] )
            throws Exception

put

public Object put(Object key,
                  Object value)
put(Object, Object) puts a new entry in the tree, overwriting any previous entry with the same key.
Parameters:
key - The value of the key. Note this must be a String, and must not be null.
value - The value to be associated with this key. Must not be null.
Returns:
the value previously associated with this key, if there was one. Otherwise null.

remove

public Object remove(Object key)
remove(Object) removes the key (and its corresponding value) from this Binary Tree. If duplicates are allowed it removes at most one entry with this key
Parameters:
key - identifies the entry to be removed
Returns:
the value that was associated with this key, if there was one. Otherwise null.

setAscending

public void setAscending(boolean ascending)
Set order. This must be called before any nodes are added to the tree. Default is ascending order
Parameters:
ascending - true indicates ascending order; false indicates descending

setComparer

public void setComparer(Comparer c)
Set the Comparer to be used for the keys in this tree. At the time this is called, the tree must be empty

setDuplicatesAllowed

public void setDuplicatesAllowed(boolean allow)
Define whether duplicate keys are allowed or not. If duplicates are allowed, objects with the same key value will be sequenced in order of arrival. If duplicates are not allowed, a new value will overwrite an existing value with the same key.

size

public int size()
size()
Returns:
the number of entries in this binary tree.