Write a method toString2 for a binary tree of integers. (On your section handout

Question

Write a method toString2 for a binary tree of integers. (On your section handout the method is called toString, but Practice-It needs you to call your method toString2 because toString is already used for another purpose.) 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. A String representation of the right subtree. For example, if a variable tree stores a reference to the following tree: +---+ | 2 | +---+ / +---+ +---+ | 8 | | 1 | +---+ +---+ / / +---+ +---+ +---+ | 0 | | 7 | | 6 | +---+ +---+ +---+ / +---+ +---+ | 4 | | 9 | +---+ +---+ Then the call tree.toString2(); should return the following String: "(2, (8, 0, empty), (1, (7, 4, empty), (6, empty, 9)))" The quotes above are used to indicate that this is a String but should not be included in the String you return. (Note: On the original section handout, this method is called toString, but Practice-It already defines a toString method for IntTree for use in other problems, so this method must be called toString2 to avoid a conflict.) Assume that you are adding this method to the IntTree class as defined below: public class IntTree { private IntTreeNode overallRoot; ... }

Explanation / Answer

ublic String toString() { StringBuilder string = new StringBuilder("["); helpToString(root, string); string.append("]"); return string.toString(); } /** * Recursive help method for toString. * * @param node * @param string */ private void helpToString(Node node, StringBuilder string) { if (node == null) return; // Tree is empty, so leave. if (node.left != null) { helpToString(node.left, string); string.append(", "); } string.append(node.data); if (node.right != null) { string.append(", "); helpToString(node.right, string); } }

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