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# Class DataStructures.TreeIterator

    java.lang.Object
        |
        +----DataStructures.TreeIterator

public abstract class TreeIterator
extends Object

Tree iterator class.

##

current
  Current position.
t
  The tree.

##

TreeIterator(BinarySearchTree)
  Construct the iterator.

##

advance()
  Advance the current position to the next node in the tree, according to the traversal scheme.
first()
  Set the current position to the first item, according to the traversal scheme.
isValid()
  Test if current position references a valid tree item.
main(String[])
retrieve()
  Return the item stored in the current position.
testItr(String, TreeIterator)

##

t

    protected BinarySearchTree t

  The tree.

current

    protected BinaryNode current

  Current position.

##

TreeIterator

    public TreeIterator(BinarySearchTree theTree)

  Construct the iterator. The current position is set to null.

  Parameters:
    theTree - the tree to which the iterator is permanently bound.

##

first

    public abstract void first()

  Set the current position to the first item, according to the traversal scheme.

isValid

    public final boolean isValid()

  Test if current position references a valid tree item.

  Returns:
    true if the current position is not null; false otherwise.

retrieve

    public final Object retrieve() throws ItemNotFound

  Return the item stored in the current position.

  Returns:
    the stored item.
  Throws: ItemNotFound
    if the current position is invalid.

advance

    public abstract void advance() throws ItemNotFound

  Advance the current position to the next node in the tree, according to the traversal scheme. If the current position is null, then throw an exception. This is the alternate strategy, that we did not use for lists.

  Throws: ItemNotFound
    if the current position is null.

main

    public static void main(String[] args)

testItr

    public static void testItr(String type,
                               TreeIterator itr)

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