Binary Trees - Building Java Programs: A Back to Basics Approach - page 1014

A clever reader might notice that this method violates the principle of Boolean
Zen that we introduced in Chapter 5. This method can be written more concisely as a
boolean expression. For example, it can be written as a single expression as follows:
private boolean contains(IntTreeNode root, int value) {
return root != null && (root.data == value ||
(value < root.data && contains(root.left, value)) ||
contains(root.right, value));
}
In this case, it is debatable whether the single expression is more readable than the
if/else version of the code. This is somewhat a matter of personal taste, so different
programmers will prefer one version over the other, but our conclusion was that the
longer version is actually easier to read in this case.
Here is the complete implementation of the IntSearchTree class:
1 // This class stores int values in a binary search tree.
2 // Duplicates are allowed. Each node of the tree has the binary
3 // search tree property.
4
5 public class IntSearchTree {
6 private IntTreeNode overallRoot;
7
8 // post: constructs an empty tree
9 public IntSearchTree() {
10 overallRoot = null;
11 }
12
13 // post: value is added to overall tree so as to preserve the
14 // binary search tree property
15 public void add( int value) {
16 overallRoot = add(overallRoot, value);
17 }
18
19 // post: value is added to given tree so as to preserve the
20 // binary search tree property
21 private IntTreeNode add(IntTreeNode root, int value) {
22 if (root == null) {
23 root = new IntTreeNode(value);
24 } else if (value <= root.data) {
25 root.left = add(root.left, value);
26 } else {
27 root.right = add(root.right, value);
28 }