Check binary tree is binary search tree (iteratively & recursively)

/**
 * CheckBinaryTreeisBinarySearchTree.java
 * 
 * Description: Implement a function to check if a binary tree is a
binary
 * search tree. (Iteratively & Recursively)
 * 
 * @author John Qiao <qiaoshun8888@gmail.com> Date: Jan 26, 2014
 */