Package org.apache.jorphan.collections

Class HashTree

java.lang.Object
org.apache.jorphan.collections.HashTree
All Implemented Interfaces:
Serializable, Cloneable, Map<Object,HashTree>
Direct Known Subclasses:
ListedHashTree
public class HashTree extends Object implements Serializable, Map<Object,HashTree>, 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:

  • Nested Class Summary

    Nested classes/interfaces inherited from interface java.util.Map

    Map.Entry<K extends Object,V extends Object>

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final IdentityHashMap<Object,HashTree>
    data
     

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
     
    HashTree()
    Creates an empty new HashTree.
     
    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.
     
    HashTree(Collection<?> keys)
    Creates a new HashTree and adds all the objects in the given collection as top-level nodes in the tree.
    protected
    HashTree(Map<Object,HashTree> _map)
    Allow subclasses to provide their own Map.

  • Method Summary

    Modifier and Type
    Method
    Description
    HashTree
    add(Object key)
    Adds an key into the HashTree at the current level.
    void
    add(Object[] keys)
    Adds all the given objects as nodes at the current level.
    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(Object[] treePath, Collection<?> values)
    Adds a series of nodes into the HashTree using the given path.
    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, 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.
    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(Collection<?> keys)
    Adds a bunch of keys into the HashTree at the current level.
    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.
    void
    add(Collection<?> treePath, Collection<?> 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(Object key)
    Creates a new tree.
    protected HashTree
    createNewTree(Collection<?> values)
    Creates a new tree.
    Set<Map.Entry<Object,HashTree>>
    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.
    HashTree
    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(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 structure 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.
    Object[]
    getArray(Collection<?> treePath)
    Recurses down into the HashTree structure using each subsequent key in the treePath argument, and returns an array of keys of the HashTree object at the end of the recursion.
    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.
    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.
    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<Object>
    keySet()
    Returns a Set of all the keys in the top-level of this HashTree.
    Collection<Object>
    list()
    Gets a Collection of all keys in the current HashTree node.
    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 structure 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.
    Collection<?>
    list(Collection<?> treePath)
    Recurses down into the HashTree structure 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.
    HashTree
    put(Object key, HashTree value)
    This is the same as calling HashTree.add(key,value).
    void
    putAll(Map<?,? extends HashTree> map)
    The Map given must also be a HashTree, otherwise an UnsupportedOperationException is thrown.
    HashTree
    remove(Object key)
    Removes the entire branch specified by the given key.
    void
    replaceKey(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(Object[] treePath, Object[] values)
    Sets a series of keys into the HashTree.
    void
    set(Object[] treePath, Collection<?> values)
    Sets a series of keys into 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, Collection<?> 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(Collection<?> values)
    Sets the nodes of the current tree to be the objects of the given collection.
    void
    set(Collection<?> treePath, Object[] values)
    Sets a series of keys into the HashTree.
    void
    set(Collection<?> treePath, Collection<?> 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<HashTree>
    values()
    Returns a collection of all the sub-trees of the current tree.

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.util.Map

    compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

  • Field Details

  • Constructor Details

    • HashTree

      public HashTree()
      Creates an empty new HashTree.

    • HashTree

      protected HashTree(Map<Object,HashTree> _map)
      Allow subclasses to provide their own Map.
      Parameters:
      _map - Map to use

    • HashTree

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

    • 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

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

  • Method Details

    • putAll

      public void putAll(Map<?,? extends HashTree> 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.
      Specified by:
      putAll in interface Map<Object,HashTree>
      See Also:

    • entrySet

      public Set<Map.Entry<Object,HashTree>> entrySet()
      Exists to satisfy the Map interface.
      Specified by:
      entrySet in interface Map<Object,HashTree>
      See Also:

    • 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.
      Specified by:
      containsValue in interface Map<Object,HashTree>
      Parameters:
      value - Object to be tested as a value.
      Returns:
      True if the HashTree contains the value, false otherwise.
      See Also:

    • put

      public HashTree put(Object key, HashTree value)
      This is the same as calling HashTree.add(key,value).
      Specified by:
      put in interface Map<Object,HashTree>
      Parameters:
      key - to use
      value - to store against key
      See Also:

    • clear

      public void clear()
      Clears the HashTree of all contents.
      Specified by:
      clear in interface Map<Object,HashTree>
      See Also:

    • values

      public Collection<HashTree> values()
      Returns a collection of all the sub-trees of the current tree.
      Specified by:
      values in interface Map<Object,HashTree>
      See Also:

    • 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(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 - the tree to be added

    • 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.
      Specified by:
      containsKey in interface Map<Object,HashTree>
      Parameters:
      o - Object to be tested as a key.
      Returns:
      True if the HashTree contains the key, false otherwise.
      See Also:

    • isEmpty

      public boolean isEmpty()
      If the HashTree is empty, true is returned, false otherwise.
      Specified by:
      isEmpty in interface Map<Object,HashTree>
      Returns:
      True if HashTree is empty, false otherwise.

    • 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, 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 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, 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[] 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

    • 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(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(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

    • add

      public HashTree add(Object key)
      Adds an key into the HashTree at the current level. If a HashTree exists for the key already, no new tree will be added
      Parameters:
      key - key to be added to HashTree
      Returns:
      newly generated tree, if no tree was found for the given key; existing key otherwise

    • 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(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 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
      Returns:
      HashTree for which value is the key

    • 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, 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 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(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(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(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
      Returns:
      HashTree for which value is the key

    • 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

    • addTreePath

      protected HashTree addTreePath(Collection<?> treePath)

    • getTree

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

    • get

      public HashTree get(Object key)
      Returns the HashTree object associated with the given key. Same as calling getTree(Object).
      Specified by:
      get in interface Map<Object,HashTree>
      See Also:

    • 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.

    • clone

      public Object clone()
      Create a clone of this HashTree. This is not a deep clone (i.e., the contents of the tree are not cloned).
      Overrides:
      clone in class Object

    • cloneTree

      protected void cloneTree(HashTree newTree)

    • 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(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.
      Parameters:
      key - object to use as the key for the top level
      Returns:
      newly created 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.
      Parameters:
      values - objects to be added to the new HashTree
      Returns:
      newly created 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

    • list

      public Collection<Object> 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(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.

    • remove

      public HashTree remove(Object key)
      Removes the entire branch specified by the given key.
      Specified by:
      remove in interface Map<Object,HashTree>
      See Also:

    • list

      public Collection<?> list(Object[] treePath)
      Recurses down into the HashTree structure 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

    • list

      public Collection<?> list(Collection<?> treePath)
      Recurses down into the HashTree structure 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

    • replaceKey

      public void replaceKey(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.
      Parameters:
      currentKey - name of the key to be replaced
      newKey - name of the new 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(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 structure 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

    • getArray

      public Object[] getArray(Collection<?> treePath)
      Recurses down into the HashTree structure 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

    • getTreePath

      protected HashTree getTreePath(Collection<?> treePath)

    • hashCode

      public int hashCode()
      Returns a hashcode for this HashTree.
      Specified by:
      hashCode in interface Map<Object,HashTree>
      Overrides:
      hashCode in class Object
      See Also:

    • 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.
      Specified by:
      equals in interface Map<Object,HashTree>
      Overrides:
      equals in class Object
      Parameters:
      o - Object to be compared against
      See Also:

    • keySet

      public Set<Object> keySet()
      Returns a Set of all the keys in the top-level of this HashTree.
      Specified by:
      keySet in interface Map<Object,HashTree>
      See Also:

    • 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

    • size

      public int size()
      Returns the number of top-level entries in the HashTree.
      Specified by:
      size in interface Map<Object,HashTree>
      See Also:

    • 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.
      Parameters:
      visitor - the visitor that wants to traverse the tree
      See Also:

    • toString

      public String toString()
      Generate a printable representation of the tree.
      Overrides:
      toString in class Object
      Returns:
      a representation of the tree