Tree.java

public class Node {
  
	private Node left;
	private Node right;
	private int value;
	
	public Node(int value) {
		this.left = null;
		this.right = null;
		this.value = value;
	}
	
	public Node(Node left, Node right, int value) {
		this.left = left;
		this.right = right;
		this.value = value;
	}
	
	public Node getLeft() { return left; }
	public Node getRight() { return right; }
	public int getValue() { return value; }
	
	public static void preOrder(Node root) {
		if(root == null) return;
		
		System.out.print(root.getValue() + " ");
		
		preOrder(root.getLeft());
		
		preOrder(root.getRight());
	}
	
	public static void inOrder(Node root) {
		if(root == null) return;
		
		inOrder(root.getLeft());
		
		System.out.print(root.getValue() + " ");
		
		inOrder(root.getRight());
	}
	
	public static void postOrder(Node root) {
		if(root == null) return;
		
		postOrder(root.getLeft());
		
		postOrder(root.getRight());
		
		System.out.print(root.getValue() + " ");
	}
	
	public static void main(String[] args) {
		Node node2 = new Node(new Node(10), new Node(3), 2);
		Node node5 = new Node(null, node2, 5);
		
		Node node7 = new Node(new Node(14), null, 7);
		Node node1 = new Node(new Node(6), new Node(4), 1);
		Node node9 = new Node(node7, node1, 9);
		
		Node root = new Node(node5, node9, 2);
		
		System.out.print("Pre-order: ");
		preOrder(root);
		System.out.println();
		
		System.out.print("In-order: ");
		inOrder(root);
		System.out.println();
		
		System.out.print("Post-order: ");
		postOrder(root);
		System.out.println();
	}

}