Again a noob question about parameterizing

Question

Im setting up an insert() for a binary tree. when i try to actually preform the setLeft or setRight command i get an error. My code is posted below.
my node class
public class BTreeNode<T extends Comparable<T>> implements Position<T> {
     public BTreeNode<T> _left;
     public BTreeNode<T> _right;
     public BTreeNode<T> _parent;
     public T            _data;
     public T element() {
          return _data;
     public BTreeNode(T c) {
          _data = c;
          _parent = null;
          _left = _right = null;
     public void setLeft(BTreeNode<T> n) {
          _left = n;
          if (n!=null) n.setParent(this);
     public void setRight(BTreeNode<T> n) {
          _right = n;
          if (n!=null) n.setParent(this);
     }my binary tree class
public class BasicBTree<T extends Comparable<T>> implements BinaryTree<T> {
     public void insert(T obj) {
     if (_root != null) {
          BTreeNode<T> runner;
          runner = _root;          
         if
                  (obj.compareTo (runner.element()) == 0){
                     System.out.println ("Object was found in tree and will not be inserted");
          else if     
             ( obj.compareTo(runner.element()) < 0 ) {
                        if (runner.hasLeft() == true){
                             runner = runner._left;
                             return;}
                        else {
                             runner.setLeft(obj); // ERROR IS HERE
          else if
               ( obj.compareTo(runner.element()) > 0 )
                         if (runner.hasRight() == true){                   
                                  runner._right = runner;
                                  return;}
                        else {
                             runner.setRight(obj); // ERROR IS HERE
     else{
          _root = new BTreeNode<T>(obj);
     return;}   
     the error i am getting says that
"The method setRight(BTreeNode<T>) in the type BTreeNode<T> is not applicable for the
arguments (T)"
or "The method setLeft(BTreeNode<T>) in the type BTreeNode<T> is not applicable for the
arguments (T)"
I had a similar question before and someone showed me where i had forgotten to parameterize my runner variable. I am thinking that this will be along the same lines although i cant imagine what it could be. The runner is already said to be part of BTreeNode<T> and setLeft and setRight are defined in the BTreeNode class so i wouldnt think that would be the problem. Anyway thanks for the time hopefully someone can help me with this.
-peter

Answer 1

Im setting up an insert() for a binary tree. Ceci already posted a solution to your problem, but may I suggest a different approach to your insert method? Trees are made for recursion!
public class BasicBTree< T extends Comparable <T> > implements BinaryTree<T> {
    private BTreeNode<T> root;
    public BasicBTree() {
        this.root = null;
    public void insert(T item) {
        BTreeNode<T> newNode = new BTreeNode<T>(item);
        if(root == null) {
            root = newNode;
        else {
            insert(root, item);
    // private "helper" method
    private void insert(BTreeNode<T> currentNode, T item) {
        int difference = currentNode._data.compareTo(item);
        if(difference < 0) {
            // IF 'currentNode' has a left node
            //    Recursively call this method using the
            //    left node of 'currentNode' and 'item'
            //    as parameters.
            // ELSE
            //    Set the left node of 'currentNode' here.
        else if(difference > 0) {
        else {
            System.out.println ("Object was found in tree and will not be inserted");
}