structure
Class BTPreorderIterator

java.lang.Object
  |
  +--structure.AbstractIterator
        |
        +--structure.BTPreorderIterator

All Implemented Interfaces:

Enumeration, Iterator

class BTPreorderIterator

extends AbstractIterator

This class implements an iterator that traverses a tree in pre-order. Each node is considered before its descendants.

Example usage:

      BinaryTree t = new BinaryTree();
      // ...tree is grown
      Iterator ti = t.preorderIterator();
      while (ti.hasNext())
      {
          System.out.println(ti.next());
      }
      ti.reset();
      while (ti.hasNext())
      { .... }
 

Field Summary

protected BinaryTree	root The root of the subtree to be considered by traversal.
protected Stack	todo The stack that maintains the state of the iterator.

Constructor Summary

BTPreorderIterator(BinaryTree root)
Constructs a pre-order traversal of subtree rooted at root.

Method Summary

Object	get() Returns the value currently being referenced by iterator.
boolean	hasNext() Returns true if some nodes of subtree have yet to be considered.
Object	next() Returns the current value and increments the iterator.
void	reset() Resets the iterator to the first node of the traversal.

Methods inherited from class structure.AbstractIterator

hasMoreElements, nextElement, remove, value

Methods inherited from class java.lang.Object

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

Field Detail

root

protected BinaryTree root

The root of the subtree to be considered by traversal.

todo

protected Stack todo

The stack that maintains the state of the iterator.

Constructor Detail

BTPreorderIterator

public BTPreorderIterator(BinaryTree root)

Constructs a pre-order traversal of subtree rooted at root.

Parameters:

root - Root of subtree to be traversed.

Method Detail

reset

public void reset()

Resets the iterator to the first node of the traversal.

Overrides:

reset in class AbstractIterator

Postcondition:

resets the iterator to retraverse

hasNext

public boolean hasNext()

Returns true if some nodes of subtree have yet to be considered.

Overrides:

hasNext in class AbstractIterator

Postcondition:

returns true iff iterator is not finished

Returns:

True iff more nodes to be considered in traversal.

get

public Object get()

Returns the value currently being referenced by iterator.

Overrides:

get in class AbstractIterator

Precondition:

hasNext()

Postcondition:

returns reference to current value

Returns:

The current value.

next

public Object next()

Returns the current value and increments the iterator. Iterator is then incremented.

Overrides:

next in class AbstractIterator

Precondition:

hasNext();

Postcondition:

returns current value, increments iterator

Returns:

The value currently being considered.