The following exercises is a method to be added to the IntTree class from this chapter. Yo...

The following exercises is a method to be added to the IntTree class from this chapter. You may define additional private methods to implement your public method if necessary. Several problem descriptions refer to the following reference binary trees:

Write a toString method for a binary tree of integers. The method should return "empty" for an empty tree. For a leaf node, it should return the data in the node as a string. For a branch node, it should return a parenthesized String that has three elements separated by commas: the data at the root, a string representation of the left subtree, and then a string representation of the right subtree. For example, if a variable t refers to reference tree #2, then the call t.toString( ) should return the following String (without the surrounding quotes):

"(2, (8, 0, empty), (1, (7, 4, empty), (6, empty, 9)))"

Reference Tree #2