Здравейте

Нещо не ми се получава примера от книгата, не мога да разбера защо, всичко е както е написано там.

public class BinaryTree {
    public static class BinaryTreeNode<T> {
        private T value;
        private boolean hasParent;
        private BinaryTreeNode<T> leftChild;
        private BinaryTreeNode<T> rightChild;

        /**
         * Constructs a binary tree node.
         *
         * @param value      - the value of the node.
         * @param leftChild  - the left child of the node.
         * @param rightChild - the right child of the node.
         */
        public BinaryTreeNode(T value,
                              BinaryTreeNode<T> leftChild,
                              BinaryTreeNode<T> rightChild) {
            if (value == null) {
                throw new IllegalArgumentException(
                        "Cannot insert null value!");
            }

            this.value = value;
            this.leftChild = leftChild;
            this.rightChild = rightChild;
        }

        /**
         * Constructs a binary tree node with no children.
         *
         * @param value - the value of the node.
         */
        public BinaryTreeNode(T value) {
            this(value, null, null);
        }

        public T getValue() {
            return this.value;
        }

        public void setValue(T value) {
            this.value = value;
        }

        public BinaryTreeNode<T> getLeftChild() {
            return this.leftChild;
        }

        public void setLeftChild(BinaryTreeNode<T> value) {
            if (value == null || value.hasParent) {
                throw new IllegalArgumentException();
            }

            value.hasParent = true;
            this.leftChild = value;
        }

        public BinaryTreeNode<T> getRightChild() {
            return this.rightChild;
        }

        public void setRightChild(BinaryTreeNode<T> value) {
            if (value == null || value.hasParent) {
                throw new IllegalArgumentException();
            }

            value.hasParent = true;
            this.rightChild = value;
        }
    }

    // The root of the tree
    private BinaryTreeNode<T> root;

    /**
     * Constructs the tree.
     * @param value - the value of the node.
     * @param children - the children of the node.
     */
    public BinaryTree(T value, BinaryTree<T> leftChild,
                      BinaryTree<T> rightChild) {

        if (value == null) {
            throw new IllegalArgumentException();
        }

        BinaryTreeNode<T> leftChildNode =
                leftChild != null ? leftChild.root : null;
        BinaryTreeNode<T> rightChildNode =
                rightChild != null ? rightChild.root : null;
        this.root = new BinaryTreeNode<T>(
                value, leftChildNode, rightChildNode);
    }

    /**
     * Constructs the tree.
     * @param value - the value of the node.
     */
    public BinaryTreeNode<T> getRoot() {
        return this.root;
    }

    /**
     * @return the left child of the root.
     */
    public BinaryTreeNode<T> getLeftChildNode() {
        if (this.root != null) {
            return this.root.getLeftChild();
        }

        return null;
    }

    /**
     * Traverses binary tree in pre-order manner.
     * @param root - the binary tree to be traversed.
     */
    private void printPreOrder(BinaryTreeNode<T> root) {
        if (root == null) {
            return;
        }

        printPreOrder(root.getLeftChild());

        System.out.print(root.getValue() + " ");

        printPreOrder(root.getRightChild());
    }

    /**
     * Traverses and prints the binary
     * tree in pre-order manner.
     */
    public void printPreOrder() {
        printPreOrder(this.root);
        System.out.println();
    }
}

public class BinaryTreeExample {
    public static void main(String[] args) {
// Create the binary tree from the sample.
        BinaryTree<Integer> binaryTree =
                new BinaryTree<Integer>(14,
                        new BinaryTree<Integer>(19,
                                new BinaryTree<Integer>(23),
                                new BinaryTree<Integer>(6,
                                        new BinaryTree<Integer>(10),
                                        new BinaryTree<Integer>(21))),
                        new BinaryTree<Integer>(15,
                                new BinaryTree<Integer>(3),
                                null));
// Traverse and print the tree in pre-order manner.
        binaryTree.printPreOrder();
    }
}

За "BinaryTree" IntelliJ ми дава след "//The root of the tree" - "Cannot resolve symbol "T" и ми дава "Т" в червено. Не мога да разбера защо тази част е извън класа, където е дефинирано "Т". Ако го вкарам вътре се омазва още повече.

За "BinaryTreeExample" ми изкарва на "Integer" че няма такъв тип параметър и дава и грешки при компилиране и опит за изпълнение. Къде е проблема, или примера си е грешно  даден?