Question

I’m trying to create a b-tree class that implements the collection interface shown below. The Issue here is that the add method takes in an object and my node classes setleftNode takes in a Node of a generic type “T”. Thus I’m getting method cant be applied to given type error when compiling. :

B-Tree Class:

public class BST<T> implements Collection<T>{
    private Node<T> _root;
    private Node<T> _current;
    private Random _rnd = new Random();

    public BST(Node<T> root) {
    _root = root;
    }
    public  Node<T> getRoot(){
    return _root;
    }
@Override
public Iterator iterator() {
    throw new UnsupportedOperationException("Not supported yet.");
}


@Override
public boolean add(Object e) {
    if (this._root != null){
            if(this._root.getLeftNode() == null){
            this._root.setLeftNode(e);
            return true;
            }
        }
        return false;
}

Node Class:

    public class Node<T>{
    private T _value;
    private Node<T> _left;
    private Node<T> _right;
    public Node (T value){
    _value = value;
    }
    public T getValue(){
    return _value;
    }
    public void setLeftNode(Node<T> node){
    _left= node;
    }
    public void setRightNode(Node<T> rNode){
    _right = rNode;
    }
    public Node getRightNode(){
    return _right;
    }
    public Node getLeftNode(){
    return _left;
    }
}

Answer 1

If BST<T> implements Collection<T> it should have add(T e). And inside setLeftNode(new Node<T>(e))):

@Override
public boolean add(T e) {
    if (this._root != null){
        if(this._root.getLeftNode() == null) {
            this._root.setLeftNode(new Node<T>(e));
            return true;
        }
    }

    return false;
}