Tree.java

// Java Binary Search Tree

public class Tree {
	Node root;
	
	// some basic test code
	public static void main(String[] args) {
		Tree tree = new Tree();
		int[] items = {5, 8, 7, 1, 9, 3, 0, 4, 6, 2};
		for (int i : items)
			tree.insert(i);
		
		System.out.println("Tree Height: " + tree.getHeight());
		System.out.println("Tree Size: " + tree.getSize());
		System.out.println("Find 3: " + tree.find(3));
		tree.inorder();
	}

	public boolean insert(int val) {
		if (root == null) {
			root = new Node(val);
			return true;
		}
		else 
			return root.insert(val);
	}
	
	public boolean find(int val) {
		if (root == null) 
			return false;
		else 
			return root.find(val);
	}
  
	public int getHeight() {
		if (root != null)
			return root.getHeight();
		else
			return 0;
	}
	
	public int getSize() {
		if (root != null)
			return root.getSize();
		else
			return 0;
	}
	
	public void preorder() {
		if (root != null) {
			System.out.println("Preorder:");
			root.preorder();
		}
	}
	
	public void postorder() {
		if (root != null) {
			System.out.println("Postorder:");
			root.postorder();
		}
	}
	
	public void inorder() {
		if (root != null) {
			System.out.println("Inorder:");
			root.inorder();
		}
	}

	private class Node {
		private Node leftChild;
		private Node rightChild;
		private int data;

		private Node(int val) {
			data = val;
			leftChild = null;
			rightChild = null;
		}

		private boolean insert(int val) {
			boolean added = false;
			if (this == null) {
				this.data = val;
				return true;
			}
			else {
				if (val < this.data) {
					if (this.leftChild == null) {
						this.leftChild = new Node(val);
						return true;
					}
					else 
						added = this.leftChild.insert(val);
				}
				else if (val > this.data) {
					if (this.rightChild == null) {
						this.rightChild = new Node(val);
						return true;
					}
					else
						added = this.rightChild.insert(val);
				}
			}
			return added;
		}
		
		private boolean find(int val) {
			boolean found = false;
			if (this == null) 
				return false;
			else {
				if (val == this.data)
					return true;                        
				else if (val < this.data && this.leftChild != null)
					found = this.leftChild.find(val);
				else if (val > this.data && this.rightChild != null)
					found = this.rightChild.find(val);
			}
			return found;
		}
		
		private int getHeight() {
			int leftHeight = 0, rightHeight = 0;
			
			if (this.leftChild != null)
				leftHeight = this.leftChild.getHeight();
						
			if (this.rightChild != null)
				rightHeight = this.rightChild.getHeight();
			
			return 1 + Math.max(leftHeight, rightHeight);
		}
		
		private int getSize() {
			int leftSize = 0, rightSize = 0;
			
			if (this.leftChild != null)
				leftSize = this.leftChild.getSize();
						
			if (this.rightChild != null)
				rightSize = this.rightChild.getSize();
			
			return 1 + leftSize + rightSize;			
		}
		
		private void preorder() {
			if (this != null) {
				System.out.println(this.data);
				if (this.leftChild != null)
					this.leftChild.preorder();
				if (this.rightChild != null)
					this.rightChild.preorder();
			}
		}
		
		private void postorder() {
			if (this != null) {
				if (this.leftChild != null)
					this.leftChild.postorder();
				if (this.rightChild != null)
					this.rightChild.postorder();
				System.out.println(this.data);
			}
		}
		
		private void inorder() {
			if (this != null) {
				if (this.leftChild != null)
					this.leftChild.inorder();
				System.out.println(this.data);
				if (this.rightChild != null)
					this.rightChild.inorder();
			}
		}
	}
}