Java/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();
            }
        }
    }
}