Check binary tree's values are where they should be in the tree.

gistfile1.java

	/**
	 * Return true if keys in this subtree are never null and are correctly sorted
	 * and are all in the range between the lower and upper (both exclusive).
	 * If either bound is null, then that means that there is no limit at this side.
	 * @param node root of subtree to examine
	 * @param lower value that all nodes must be greater than.  If null, then
	 * there is no lower bound.
	 * @param upper value that all nodes must be less than. If null,
	 * then there is no upper bound.
	 * @return true if the subtree is fine.  If false is returned, a problem
	 * should be reported.
	 */
	private boolean checkInRange(Node<K,V> node, K lower, K upper) {
		if (node != null){
			if (node.value == null) return report("null data in tree");
			if (lower != null)
				if (comparator.compare(node.key, lower) < 0) return report("under the bounds");
			if (upper != null)
				if (comparator.compare(node.key, upper) > 0) return report("above the bounds");

			checkInRange(node.right, node.key, upper);
			checkInRange(node.left, lower, node.key);
		}
		return true;
	}