org.apache.jorphan.collections

Class HashTree

Implemented Interfaces:
Cloneable, Map, Serializable
Known Direct Subclasses:
ListedHashTree, SortedHashTree

public class HashTree
extends Object
implements Serializable, Map, Cloneable

This class is used to create a tree structure of objects. Each element in the tree is also a key to the next node down in the tree. It provides many ways to add objects and branches, as well as many ways to retrieve.

HashTree implements the Map interface for convenience reasons. The main difference between a Map and a HashTree is that the HashTree organizes the data into a recursive tree structure, and provides the means to manipulate that structure.

Of special interest is the traverse(HashTreeTraverser) method, which provides an expedient way to traverse any HashTree by implementing the HashTreeTraverser interface in order to perform some operation on the tree, or to extract information from the tree.

See Also:
HashTreeTraverser, SearchByClass

Field Summary

protected Map
data

Constructor Summary

HashTree()
Creates an empty new HashTree.
HashTree(Collection keys)
Creates a new HashTree and adds all the objects in the given collection as top-level nodes in the tree.
HashTree(Map _map)
Allow subclasses to provide their own Map.
HashTree(Object key)
Creates a new HashTree and adds the given object as a top-level node.
HashTree(Object[] keys)
Creates a new HashTree and adds all the objects in the given array as top-level nodes in the tree.

Method Summary

void
add(Collection keys)
Adds a bunch of keys into the HashTree at the current level.
void
add(Collection treePath, Collection values)
Adds a series of nodes into the HashTree using the given path.
HashTree
add(Collection treePath, Object value)
Adds a series of nodes into the HashTree using the given path.
void
add(Collection treePath, Object[] values)
Adds a series of nodes into the HashTree using the given path.
HashTree
add(Object key)
Adds an key into the HashTree at the current level.
void
add(Object key, Collection values)
Adds a key as a node at the current level and then adds all the objects in the second argument as nodes of the new node.
HashTree
add(Object key, Object value)
Adds a key and it's value in the HashTree.
void
add(Object key, Object[] values)
Adds a key and it's values in the HashTree.
void
add(Object key, HashTree subTree)
Adds a key as a node at the current level and then adds the given HashTree to that new node.
void
add(Object[] keys)
Adds all the given objects as nodes at the current level.
void
add(Object[] treePath, Collection values)
Adds a series of nodes into the HashTree using the given path.
HashTree
add(Object[] treePath, Object value)
void
add(Object[] treePath, Object[] values)
Adds a series of nodes into the HashTree using the given path.
void
add(HashTree newTree)
Adds all the nodes and branches of the given tree to this tree.
protected HashTree
addTreePath(Collection treePath)
void
clear()
Clears the HashTree of all contents.
Object
clone()
Create a clone of this HashTree.
protected void
cloneTree(HashTree newTree)
boolean
containsKey(Object o)
If the HashTree contains the given object as a key at the top level, then a true result is returned, otherwise false.
boolean
containsValue(Object value)
Implemented as required by the Map interface, but is not very useful here.
protected HashTree
createNewTree()
Creates a new tree.
protected HashTree
createNewTree(Collection values)
Creates a new tree.
protected HashTree
createNewTree(Object key)
Creates a new tree.
Set
entrySet()
Exists to satisfy the Map interface.
boolean
equals(Object o)
Compares all objects in the tree and verifies that the two trees contain the same objects at the same tree levels.
Object
get(Object key)
Returns the HashTree object associated with the given key.
Object[]
getArray()
Gets an array of all keys in the current HashTree node.
Object[]
getArray(Collection treePath)
Recurses down into the HashTree stucture using each subsequent key in the treePath argument, and returns an array of keys of the HashTree object at the end of the recursion.
Object[]
getArray(Object key)
Gets an array of all keys in the HashTree mapped to the given key of the current HashTree object (in other words, one level down).
Object[]
getArray(Object[] treePath)
Recurses down into the HashTree stucture using each subsequent key in the array of keys, and returns an array of keys of the HashTree object at the end of the recursion.
HashTree
getTree(Collection treePath)
Gets the HashTree object mapped to the last key in the SortedSet by recursing through the HashTree structure one key at a time.
HashTree
getTree(Object key)
Gets the HashTree mapped to the given key.
HashTree
getTree(Object[] treePath)
Gets the HashTree object mapped to the last key in the array by recursing through the HashTree structure one key at a time.
protected HashTree
getTreePath(Collection treePath)
int
hashCode()
Returns a hashcode for this HashTree.
boolean
isEmpty()
If the HashTree is empty, true is returned, false otherwise.
Set
keySet()
Returns a Set of all the keys in the top-level of this HashTree.
Collection
list()
Gets a Collection of all keys in the current HashTree node.
Collection
list(Collection treePath)
Recurses down into the HashTree stucture using each subsequent key in the List of keys, and returns the Set of keys of the HashTree object at the end of the recursion.
Collection
list(Object key)
Gets a Set of all keys in the HashTree mapped to the given key of the current HashTree object (in other words, one level down.
Collection
list(Object[] treePath)
Recurses down into the HashTree stucture using each subsequent key in the array of keys, and returns the Set of keys of the HashTree object at the end of the recursion.
Object
put(Object key, Object value)
This is the same as calling HashTree.add(key,value).
void
putAll(Map map)
The Map given must also be a HashTree, otherwise an UnsupportedOperationException is thrown.
Object
remove(Object key)
Removes the entire branch specified by the given key.
void
replace(Object currentKey, Object newKey)
Finds the given current key, and replaces it with the given new key.
HashTree
search(Object key)
Searches the HashTree structure for the given key.
void
set(Collection values)
Sets the nodes of the current tree to be the objects of the given collection.
void
set(Collection treePath, Collection values)
Sets a series of keys into the HashTree.
void
set(Collection treePath, Object[] values)
Sets a series of keys into the HashTree.
void
set(Object key, Collection values)
Sets a key and its values in the HashTree.
void
set(Object key, Object value)
Sets a key and it's value in the HashTree.
void
set(Object key, Object[] values)
Sets a key and its values in the HashTree.
void
set(Object key, HashTree t)
Sets a key into the current tree and assigns it a HashTree as its subtree.
void
set(Object[] treePath, Collection values)
Sets a series of keys into the HashTree.
void
set(Object[] treePath, Object[] values)
Sets a series of keys into the HashTree.
int
size()
Returns the number of top-level entries in the HashTree.
String
toString()
Generate a printable representation of the tree.
void
traverse(HashTreeTraverser visitor)
Allows any implementation of the HashTreeTraverser interface to easily traverse (depth-first) all the nodes of the HashTree.
Collection
values()
Returns a collection of all the sub-trees of the current tree.

Field Details

data

protected final Map data

Constructor Details

HashTree

public HashTree()
Creates an empty new HashTree.

HashTree

public HashTree(Collection keys)
Creates a new HashTree and adds all the objects in the given collection as top-level nodes in the tree.
Parameters:
keys - a collection of objects to be added to the created HashTree.

HashTree

protected HashTree(Map _map)
Allow subclasses to provide their own Map.

HashTree

public HashTree(Object key)
Creates a new HashTree and adds the given object as a top-level node.
Parameters:
key -

HashTree

public HashTree(Object[] keys)
Creates a new HashTree and adds all the objects in the given array as top-level nodes in the tree.

Method Details

add

public void add(Collection keys)
Adds a bunch of keys into the HashTree at the current level.
Parameters:
keys - Collection of Keys to be added to HashTree.

add

public void add(Collection treePath,
                Collection values)
Adds a series of nodes into the HashTree using the given path. The first argument is a SortedSet that represents a path to a specific node in the tree. If the path doesn't already exist, it is created (the objects are added along the way). At the path, all the objects in the second argument are added as nodes.
Parameters:
treePath - a SortedSet of objects representing a path
values - Collection of values to be added as keys to bottom-most node

add

public HashTree add(Collection treePath,
                    Object value)
Adds a series of nodes into the HashTree using the given path. The first argument is a List that represents a path to a specific node in the tree. If the path doesn't already exist, it is created (the objects are added along the way). At the path, the object in the second argument is added as a node.
Parameters:
treePath - a list of objects representing a path
value - Object to add as a node to bottom-most node

add

public void add(Collection treePath,
                Object[] values)
Adds a series of nodes into the HashTree using the given path. The first argument is a List that represents a path to a specific node in the tree. If the path doesn't already exist, it is created (the objects are added along the way). At the path, all the objects in the second argument are added as nodes.
Parameters:
treePath - a list of objects representing a path
values - array of values to be added as keys to bottom-most node

add

public HashTree add(Object key)
Adds an key into the HashTree at the current level.
Parameters:
key - key to be added to HashTree

add

public void add(Object key,
                Collection values)
Adds a key as a node at the current level and then adds all the objects in the second argument as nodes of the new node.
Parameters:
key - key to be added
values - Collection of objects to be added as keys in the secondary node

add

public HashTree add(Object key,
                    Object value)
Adds a key and it's value in the HashTree. The first argument becomes a node at the current level, and the second argument becomes a node of it.
Parameters:
key - key to be added
value - value to be added as a key in the secondary node

add

public void add(Object key,
                Object[] values)
Adds a key and it's values in the HashTree. The first argument becomes a node at the current level, and adds all the values in the array to the new node.
Parameters:
key - key to be added
values - array of objects to be added as keys in the secondary node

add

public void add(Object key,
                HashTree subTree)
Adds a key as a node at the current level and then adds the given HashTree to that new node.
Parameters:
key - key to create in this tree
subTree - sub tree to add to the node created for the first argument.

add

public void add(Object[] keys)
Adds all the given objects as nodes at the current level.
Parameters:
keys - Array of Keys to be added to HashTree.

add

public void add(Object[] treePath,
                Collection values)
Adds a series of nodes into the HashTree using the given path. The first argument is an array that represents a path to a specific node in the tree. If the path doesn't already exist, it is created (the objects are added along the way). At the path, all the objects in the second argument are added as nodes.
Parameters:
treePath - an array of objects representing a path
values - collection of values to be added as keys to bottom-most node

add

public HashTree add(Object[] treePath,
                    Object value)

add

public void add(Object[] treePath,
                Object[] values)
Adds a series of nodes into the HashTree using the given path. The first argument is an array that represents a path to a specific node in the tree. If the path doesn't already exist, it is created (the objects are added along the way). At the path, all the objects in the second argument are added as nodes.
Parameters:
treePath - an array of objects representing a path
values - array of values to be added as keys to bottom-most node

add

public void add(HashTree newTree)
Adds all the nodes and branches of the given tree to this tree. Is like merging two trees. Duplicates are ignored.
Parameters:
newTree -

addTreePath

protected HashTree addTreePath(Collection treePath)

clear

public void clear()
Clears the HashTree of all contents.

clone

public Object clone()
Create a clone of this HashTree. This is not a deep clone (ie, the contents of the tree are not cloned).

cloneTree

protected void cloneTree(HashTree newTree)

containsKey

public boolean containsKey(Object o)
If the HashTree contains the given object as a key at the top level, then a true result is returned, otherwise false.
Parameters:
o - Object to be tested as a key.
Returns:
True if the HashTree contains the key, false otherwise.

containsValue

public boolean containsValue(Object value)
Implemented as required by the Map interface, but is not very useful here. All 'values' in a HashTree are HashTree's themselves.
Parameters:
value - Object to be tested as a value.
Returns:
True if the HashTree contains the value, false otherwise.

createNewTree

protected HashTree createNewTree()
Creates a new tree. This method exists to allow inheriting classes to generate the appropriate types of nodes. For instance, when a node is added, it's value is a HashTree. Rather than directly calling the HashTree() constructor, the createNewTree() method is called. Inheriting classes should override these methods and create the appropriate subclass of HashTree.
Returns:
HashTree

createNewTree

protected HashTree createNewTree(Collection values)
Creates a new tree. This method exists to allow inheriting classes to generate the appropriate types of nodes. For instance, when a node is added, it's value is a HashTree. Rather than directly calling the HashTree() constructor, the createNewTree() method is called. Inheriting classes should override these methods and create the appropriate subclass of HashTree.
Returns:
HashTree

createNewTree

protected HashTree createNewTree(Object key)
Creates a new tree. This method exists to allow inheriting classes to generate the appropriate types of nodes. For instance, when a node is added, it's value is a HashTree. Rather than directly calling the HashTree() constructor, the createNewTree() method is called. Inheriting classes should override these methods and create the appropriate subclass of HashTree.
Returns:
HashTree

entrySet

public Set entrySet()
Exists to satisfy the Map interface.

equals

public boolean equals(Object o)
Compares all objects in the tree and verifies that the two trees contain the same objects at the same tree levels. Returns true if they do, false otherwise.
Parameters:
o - Object to be compared against

get

public Object get(Object key)

getArray

public Object[] getArray()
Gets an array of all keys in the current HashTree node. If the HashTree represented a file system, this would be like getting an array of all the files in the current folder.
Returns:
array of all keys in this HashTree.

getArray

public Object[] getArray(Collection treePath)
Recurses down into the HashTree stucture using each subsequent key in the treePath argument, and returns an array of keys of the HashTree object at the end of the recursion. If the HashTree represented a file system, this would be like getting a list of all the files in a directory specified by the treePath, relative from the current directory.
Parameters:
treePath - list of keys used to recurse into HashTree structure
Returns:
array of all keys found in end HashTree

getArray

public Object[] getArray(Object key)
Gets an array of all keys in the HashTree mapped to the given key of the current HashTree object (in other words, one level down). If the HashTree represented a file system, this would like getting a list of all files in a sub-directory (of the current directory) specified by the key argument.
Parameters:
key - key used to find HashTree to get list of
Returns:
array of all keys in found HashTree

getArray

public Object[] getArray(Object[] treePath)
Recurses down into the HashTree stucture using each subsequent key in the array of keys, and returns an array of keys of the HashTree object at the end of the recursion. If the HashTree represented a file system, this would be like getting a list of all the files in a directory specified by the treePath, relative from the current directory.
Parameters:
treePath - array of keys used to recurse into HashTree structure
Returns:
array of all keys found in end HashTree

getTree

public HashTree getTree(Collection treePath)
Gets the HashTree object mapped to the last key in the SortedSet by recursing through the HashTree structure one key at a time.
Parameters:
treePath - Collection of keys
Returns:
HashTree at the end of the recursion

getTree

public HashTree getTree(Object key)
Gets the HashTree mapped to the given key.
Parameters:
key - Key used to find appropriate HashTree()

getTree

public HashTree getTree(Object[] treePath)
Gets the HashTree object mapped to the last key in the array by recursing through the HashTree structure one key at a time.
Parameters:
treePath - array of keys.
Returns:
HashTree at the end of the recursion.

getTreePath

protected HashTree getTreePath(Collection treePath)

hashCode

public int hashCode()
Returns a hashcode for this HashTree.

isEmpty

public boolean isEmpty()
If the HashTree is empty, true is returned, false otherwise.
Returns:
True if HashTree is empty, false otherwise.

keySet

public Set keySet()
Returns a Set of all the keys in the top-level of this HashTree.

list

public Collection list()
Gets a Collection of all keys in the current HashTree node. If the HashTree represented a file system, this would be like getting a collection of all the files in the current folder.
Returns:
Set of all keys in this HashTree

list

public Collection list(Collection treePath)
Recurses down into the HashTree stucture using each subsequent key in the List of keys, and returns the Set of keys of the HashTree object at the end of the recursion. If the HashTree represented a file system, this would be like getting a list of all the files in a directory specified by the treePath, relative from the current directory.
Parameters:
treePath - List of keys used to recurse into HashTree structure
Returns:
Set of all keys found in end HashTree

list

public Collection list(Object key)
Gets a Set of all keys in the HashTree mapped to the given key of the current HashTree object (in other words, one level down. If the HashTree represented a file system, this would like getting a list of all files in a sub-directory (of the current directory) specified by the key argument.
Parameters:
key - key used to find HashTree to get list of
Returns:
Set of all keys in found HashTree.

list

public Collection list(Object[] treePath)
Recurses down into the HashTree stucture using each subsequent key in the array of keys, and returns the Set of keys of the HashTree object at the end of the recursion. If the HashTree represented a file system, this would be like getting a list of all the files in a directory specified by the treePath, relative from the current directory.
Parameters:
treePath - Array of keys used to recurse into HashTree structure
Returns:
Set of all keys found in end HashTree

put

public Object put(Object key,
                  Object value)
This is the same as calling HashTree.add(key,value).
Parameters:
key - to use
value - to store against key

putAll

public void putAll(Map map)
The Map given must also be a HashTree, otherwise an UnsupportedOperationException is thrown. If it is a HashTree, this is like calling the add(HashTree) method.

remove

public Object remove(Object key)
Removes the entire branch specified by the given key.

replace

public void replace(Object currentKey,
                    Object newKey)
Finds the given current key, and replaces it with the given new key. Any tree structure found under the original key is moved to the new key.

search

public HashTree search(Object key)
Searches the HashTree structure for the given key. If it finds the key, it returns the HashTree mapped to the key. If it finds nothing, it returns null.
Parameters:
key - Key to search for
Returns:
HashTree mapped to key, if found, otherwise null

set

public void set(Collection values)
Sets the nodes of the current tree to be the objects of the given collection. Any nodes previously in the tree are removed.
Parameters:
values - Collection of objects to set as nodes.

set

public void set(Collection treePath,
                Collection values)
Sets a series of keys into the HashTree. It sets up the first object in the key list as a key in the current node, recurses into the next HashTree node through that key and adds the second object in the list. Continues recursing in this manner until the end of the first list is reached, at which point all the values of the Collection of values are set as keys to the bottom-most node. Any previously existing keys of that bottom node are lost.
Parameters:
treePath - list of keys to put into HashTree
values - collection of values to be added as keys to bottom-most node

set

public void set(Collection treePath,
                Object[] values)
Sets a series of keys into the HashTree. It sets up the first object in the key list as a key in the current node, recurses into the next HashTree node through that key and adds the second object in the list. Continues recursing in this manner until the end of the first list is reached, at which point all the values of the array of values are set as keys to the bottom-most node. Any previously existing keys of that bottom node are removed.
Parameters:
treePath - collection of keys to put into HashTree
values - array of values to be added as keys to bottom-most node

set

public void set(Object key,
                Collection values)
Sets a key and its values in the HashTree. It sets up a key in the current node, and then creates a node for that key, and set all the values in the array as keys in the new node. Any keys previously held under the given key are removed.
Parameters:
key - key to be set up
values - Collection of objects to be added as keys in the secondary node

set

public void set(Object key,
                Object value)
Sets a key and it's value in the HashTree. It actually sets up a key, and then creates a node for the key and sets the value to the new node, as a key. Any previous nodes that existed under the given key are lost.
Parameters:
key - key to be set up
value - value to be set up as a key in the secondary node

set

public void set(Object key,
                Object[] values)
Sets a key and its values in the HashTree. It sets up a key in the current node, and then creates a node for that key, and sets all the values in the array as keys in the new node. Any keys previously held under the given key are lost.
Parameters:
key - Key to be set up
values - Array of objects to be added as keys in the secondary node

set

public void set(Object key,
                HashTree t)
Sets a key into the current tree and assigns it a HashTree as its subtree. Any previous entries under the given key are removed.
Parameters:
key - key to be set up
t - HashTree that the key maps to

set

public void set(Object[] treePath,
                Collection values)
Sets a series of keys into the HashTree. It sets up the first object in the key array as a key in the current node, recurses into the next HashTree node through that key and adds the second object in the array. Continues recursing in this manner until the end of the first array is reached, at which point all the values of the Collection of values are set as keys to the bottom-most node. Any keys previously held by the bottom-most node are lost.
Parameters:
treePath - array of keys to put into HashTree
values - Collection of values to be added as keys to bottom-most node

set

public void set(Object[] treePath,
                Object[] values)
Sets a series of keys into the HashTree. It sets up the first object in the key array as a key in the current node, recurses into the next HashTree node through that key and adds the second object in the array. Continues recursing in this manner until the end of the first array is reached, at which point all the values of the second array are set as keys to the bottom-most node. All previous keys of that bottom-most node are removed.
Parameters:
treePath - array of keys to put into HashTree
values - array of values to be added as keys to bottom-most node

size

public int size()
Returns the number of top-level entries in the HashTree.

toString

public String toString()
Generate a printable representation of the tree.
Returns:
a representation of the tree

traverse

public void traverse(HashTreeTraverser visitor)
Allows any implementation of the HashTreeTraverser interface to easily traverse (depth-first) all the nodes of the HashTree. The Traverser implementation will be given notification of each node visited.

values

public Collection values()
Returns a collection of all the sub-trees of the current tree.

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