Binary Tree

public class BinaryTree
{

    Node root;

    public void addNode(int key, String name)
    {

        // Create a new Node and initialize it

        Node newNode = new Node(key, name);

        // If there is no root this becomes root

        if (root == null)
        {

            root = newNode;

        }
        else
        {

            // Set root as the Node we will start
            // with as we traverse the tree

            Node focusNode = root;

            // Future parent for our new Node

            Node parent;

            while (true)
            {

                // root is the top parent so we start
                // there

                parent = focusNode;

                // Check if the new node should go on
                // the left side of the parent node

                if (key < focusNode.key)
                {

                    // Switch focus to the left child

                    focusNode = focusNode.leftChild;

                    // If the left child has no children

                    if (focusNode == null)
                    {

                        // then place the new node on the left of it

                        parent.leftChild = newNode;
                        return; // All Done

                    }

                }
                else
                { // If we get here put the node on the right

                    focusNode = focusNode.rightChild;

                    // If the right child has no children

                    if (focusNode == null)
                    {

                        // then place the new node on the right of it

                        parent.rightChild = newNode;
                        return; // All Done

                    }

                }

            }
        }

    }

    // All nodes are visited in ascending order
    // Recursion is used to go to one node and
    // then go to its child nodes and so forth

    public void inOrderTraverseTree(Node focusNode)
    {

        if (focusNode != null)
        {

            // Traverse the left node

            inOrderTraverseTree(focusNode.leftChild);

            // Visit the currently focused on node

            System.out.println(focusNode);

            // Traverse the right node

            inOrderTraverseTree(focusNode.rightChild);

        }

    }

    public void preorderTraverseTree(Node focusNode)
    {

        if (focusNode != null)
        {

            System.out.println(focusNode);

            preorderTraverseTree(focusNode.leftChild);
            preorderTraverseTree(focusNode.rightChild);

        }

    }

    public void postOrderTraverseTree(Node focusNode)
    {

        if (focusNode != null)
        {

            postOrderTraverseTree(focusNode.leftChild);
            postOrderTraverseTree(focusNode.rightChild);

            System.out.println(focusNode);

        }

    }

    public Node findNode(int key)
    {

        // Start at the top of the tree

        Node focusNode = root;

        // While we haven't found the Node
        // keep looking

        while (focusNode.key != key)
        {

            // If we should search to the left

            if (key < focusNode.key)
            {

                // Shift the focus Node to the left child

                focusNode = focusNode.leftChild;

            }
            else
            {

                // Shift the focus Node to the right child

                focusNode = focusNode.rightChild;

            }

            // The node wasn't found

            if (focusNode == null)
                return null;

        }

        return focusNode;

    }

    public static void main(String[] args)
    {

        BinaryTree theTree = new BinaryTree();

        theTree.addNode(50, "Boss");

        theTree.addNode(25, "Vice President");

        theTree.addNode(15, "Office Manager");

        theTree.addNode(30, "Secretary");

        theTree.addNode(75, "Sales Manager");

        theTree.addNode(85, "Salesman 1");

        // Different ways to traverse binary trees

        theTree.inOrderTraverseTree(theTree.root);

        System.out.println();
        theTree.preorderTraverseTree(theTree.root);
        System.out.println();
        theTree.postOrderTraverseTree(theTree.root);

        // Find the node with key 75

        System.out.println("\nNode with the key 75");

        System.out.println(theTree.findNode(75));

    }
}

class Node
{

    int key;
    String name;

    Node leftChild;
    Node rightChild;

    Node(int key, String name)
    {

        this.key = key;
        this.name = name;

    }

    @Override
    public String toString()
    {

        return name + " has the key " + key;

        /*
         * return name + " has the key " + key + "\nLeft Child: " + leftChild + "\nRight Child: " +
         * rightChild + "\n";
         */

    }

}