java binary tree program for inorder, preorder, postorder

import java.util.Queue;
import java.util.LinkedList;
public class TreeTraverse
{
private static class Node<T>
{
public Node<T> left;
public Node<T>right;
public T data;
public Node (T data)
{
this.data=data;
}
public Node <T>getleft()
{
return this.left;
}
public void setleft(Node <T>left)
{
this.left=left;
}
public Node<T>getright()
{
return this.right;
}
public void setright(Node<T>right)
{
this.right=right;
}
}
public static void preorder(Node<?>n)
{
if(n!=null)
{
System.out.println(n.data+"  ");
preorder(n.getleft());
preorder(n.getright());
}
}
public static void inorder(Node<?>n)
{
if(n!=null)
{
System.out.println(n.data+" ");
preorder(n.getleft());
preorder(n.getright());
}
}
public static void postorder(Node<?>n)
{
if(n!=null)
{
postorder(n.getleft());
postorder(n.getright());
System.out.println(n.data+" ");
}
}
public static void main(final String[]args)
{
Node<Integer>one=new Node<Integer>(1);
Node<Integer>two=new Node<Integer>(2);
Node<Integer>three=new Node<Integer>(3);
Node<Integer>four=new Node<Integer>(4);
Node<Integer>five=new Node<Integer>(5);
Node<Integer>six=new Node<Integer>(6);
Node<Integer>seven=new Node<Integer>(7);
Node<Integer>eight=new Node<Integer>(8);
Node<Integer>nine=new Node<Integer>(9);
one.setleft(two);
one.setright(three);
two.setleft(four);
two.setright(five);
three.setleft(six);
four.setleft(seven);
six.setleft(eight);
six.setright(nine);
System.out.println("PREORDER IS:");
preorder(one);
System.out.println();
System.out.println("INORDER IS:");
inorder(one);
System.out.println();
System.out.println("POSTORDER IS:");
postorder(one);
System.out.println();
}
}