how to print leaf nodes in a binary search tree

The logic here is simple. Recursively go through left and then right elements, when the base condition is met (i.e, when r==null), add a check to see if the node’s left and right wings are null and if they are null print the value of the node.

Input binary search tree:

    // print leaf nodes
    public void leafNodes(BinaryNode r) {
    	if(r!= null) {
    		leafNodes(r.left);
    		leafNodes(r.right);

    		if(r.left == null && r.right == null) {
    			System.out.println(r.element);
    		}
    	}
    }

Note: This logic is same is recursive post order traversal, but instead of just printing the node value after left&right traversals we check to see if left&right children are null and then print the node value.