Binary Search Tree

/**
 * Binary Search Tree
 */
public class BST {
    //attributes
    private Object item; //data container
    private BST left,right,parent;

    //constructor
    public BST(Object item) { this.item = item; }
    public BST()            {}

    //setters
    public void setItem(Object item)    { this.item = item; }
    public void setLeft(BST left)       { this.left = left; }
    public void setRight(BST right)     { this.right = right; }
    public void setParent(BST parent)   { this.parent = parent; }

    //setters
    public Object getItem()     { return item; }
    public BST getLeft()        { return left; }
    public BST getRight()       { return right; }
    public BST getParent()      { return parent; }

    public BST addNode(Object item, BST root) {
        //create a new node(tree)
        BST node = new BST(item);
            if(root == null) root = node;
            else {
                Comparable c =  (Comparable)root.getItem();
                if(c.compareTo(item) > 0) {
                    root.left = addNode(item, root.getLeft()); //recursive call
                }
                if(c.compareTo(item) <= 0) {
                    root.right = addNode(item, root.getRight());
                }
            }
        return root; //return the updated root
    }

    public void preOder(BST root) {
        if(root != null) {
            System.out.print(root.getItem()); //Logical marker
            preOder(root.getLeft());
            preOder(root.getRight());
        }
    }

    public void inOder(BST root) {
        if(root != null) {
            inOder(root.getLeft());
            System.out.print(root.getItem()); //Logical marker
            inOder(root.getRight());
        }
    }

    public void postOder(BST root) {
        if(root != null) {
            postOder(root.getLeft());
            postOder(root.getRight());
            System.out.print(root.getItem()); //Logical marker
        }
    }

    public void levelOder(BST root) {
        java.util.Queue<BST> q = new java.util.LinkedList<BST>();
            q.add(root);
            while(!q.isEmpty()) {
                BST temp = q.poll();
                System.out.print(temp.getItem());
                if(temp.getLeft() != null) {
                    q.add(temp.getLeft());
                }
                if(temp.getRight() != null) {
                    q.add(temp.getRight());
                }
            }
    }

    static public void main(String... args) {
        BST bst = null;

        bst = new BST().addNode(new String("6"), bst);
        bst = new BST().addNode(new String("4"), bst);
        bst = new BST().addNode(new String("9"), bst);
        bst = new BST().addNode(new String("7"), bst);
        bst = new BST().addNode(new String("2"), bst);
        bst = new BST().addNode(new String("8"), bst);
        bst = new BST().addNode(new String("5"), bst);
        bst = new BST().addNode(new String("0"), bst);
        bst = new BST().addNode(new String("3"), bst);
        bst = new BST().addNode(new String("1"), bst);
        bst = new BST().addNode(new String("6"), bst);

        System.out.print("Pre-Order: ");
        new BST().preOder(bst);
        System.out.print("\nIn-Order: ");
        new BST().inOder(bst);
        System.out.print("\nPost-Order: ");
        new BST().postOder(bst);
        System.out.print("\nLevel-Order: ");
        new BST().levelOder(bst);

    }

}//End of the class