how to print binary tree in java code example

Example: print all nodes in binary tree java

public class Node<E>{
	private Node left;
  	private Node right;
  	private E elem;
  	public void printNodes(){
    	if(left!=null){
        	left.printNodes();
        }
      	System.out.println(elem);
      	if(right!=null){
        	right.printNodes();
        }
    }
}