util
Class StringTreeTable

java.lang.Object
  |
  +--util.StringTreeTable

public class StringTreeTable

extends Object

implements Serializable

A hash table which allows prefix lookup. The table is indexed by strings, and divider substring ("." by default) are used to create a tree structure. Performing a lookup then gives the matching entry and/or any parents in the tree. The empty string "" is always the root key. For example, a StringTreeTable with `apple', `apple.pie' and `apple.juice' as keys has the following internal structure:

 [empty string] ---> apple +--> apple.juice
                           |
                           +--> apple.pie
 

Performing a lookup on "apple.pie" will yield the objects for "apple.pie", "apple", and the empty string "". A get("anteater") will yield a match for just the empty string key. StringTreeTable allows there to be more than one value for a given key; it will return all such values with the get() method.

See Also:

Serializable, Serialized Form

Field Summary

static String

DEFAULT_WHITE

Constructor Summary

StringTreeTable()
Creates a StringTreeTable using the default (".") divider string.

StringTreeTable(String divider)
Creates a StringTreeTable with the given String as the divider.

Method Summary

void	add(String nm, Object o) Adds a new key,object pair into the tree.
HashSet	get(String nm) Gets the set of matching objects in the tree structure.
HashSet	getChildren(String nm)
static void	main(String[] args)
Iterator	nodes() Returns all the keys in the tree.
int	nuke(Object o) Removes an object from all keys in the tree.
boolean	remove(String nm, Object o) Removes a given key,value pair.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_WHITE

public static final String DEFAULT_WHITE

Constructor Detail

StringTreeTable

public StringTreeTable()

Creates a StringTreeTable using the default (".") divider string.

StringTreeTable

public StringTreeTable(String divider)

Creates a StringTreeTable with the given String as the divider.

Parameters:

divider - The divider string.

Method Detail

get

public HashSet get(String nm)

Gets the set of matching objects in the tree structure. This will give you all the values for the tree's keys, leading from the root to the given key. This will never return null; if there are no matches, this will return a HashSet with no objects in it.

Parameters:

nm - The value to search for.

Returns:

a HashSet including all matches.

add

public void add(String nm,
                Object o)

Adds a new key,object pair into the tree. If the key already exists, the object is added to the table anyway and both it and the pre-existing objects will be returned when requested.

Parameters:

nm - The key value to be inserted into the table.

o - The object value for the given key.

remove

public boolean remove(String nm,
                      Object o)

Removes a given key,value pair. The pair is only removed if the key is in the tree table and the object is a match for that key.

Parameters:

nm - The key to be removed, if present.

o - The object to be removed, if present.

Returns:

true if the object and key were in the table.

nuke

public int nuke(Object o)

Removes an object from all keys in the tree.

Parameters:

o - The object to be removed, if present.

Returns:

The number of keys for which the object was present.

nodes

public Iterator nodes()

Returns all the keys in the tree. The sequence in which keys are returned is not defined.

Returns:

An iterator over the tree's keys in some sequence.

getChildren

public HashSet getChildren(String nm)

Returns:

list of all folks which are in nodes in the given node or its children.

main

public static void main(String[] args)

toString

public String toString()

Overrides:

toString in class Object