InorderTraversalUsingStack.java

    class Node<E> {
      E data;
      Node<E> left;
      Node<E> right;
      E getData() {return data;}
      Node<E> leftChild() {return this.left;}
      Node<E> rightChild() {return this.right;}
    }
    
    static <T> void iterateBSTInOrder(Node<T> node) {
      boolean done = false;
      Node<T> nodePtr = node;
      Stack<Node<T>> stack = new Stack<>();
      
      while (!done) {
        //until done, keep looking for left child
        if (nodePtr != null) {
          stack.push(nodePtr);
          nodePtr = nodePtr.leftChild();
        }
        else {
          //if no leftChild remains, go into right subtree and find left children
          if (!stack.isEmpty()) {
            nodePtr = stack.pop();
            System.out.println(nodePtr.getData());
            nodePtr = nodePtr.rightChild();
          }
          else {
            //if there's nothing left in the stack, we've already traversed the entire tree
            done = true;
          }
        }
      }
    }