java binary tree

tree.java

package tree; // and change class name at line 237!

class Tree {

    class Node { // inner class!

        private int value;
        private Node parent;
        private Node right;
        private Node left;

        public int getValue() {
            return value;
        }
    }

    private Node root;

    public boolean isEmpty() {
        return root == null;
    }

    public void showTree() {
        System.out.print("\n");
        showTree(root);
        System.out.print("\n\n");
    }

    private void showTree(Node elem) {
        if (elem != null) {
            showTree(elem.left);
            System.out.print(elem.getValue() + ", ");
            showTree(elem.right);
        }
    }

    public Node getRoot() {
        return root;
    }

    public int getCount() {
        int count = 0;
        count = getCount(root, count);
        return count;
    }

    private int getCount(Node elem, int count) {
        if (elem != null) {
            count = getCount(elem.left, count);
            count++;
            count = getCount(elem.right, count);
        }
        return count;
    }

    public Node findNode(int value) {
        if (isEmpty()) {
            return null;
        } else {
            Node f = root;
            while (true) {
                if (value < f.value) {
                    if (f.left != null) {
                        f = f.left;
                    } else {
                        break;
                    }
                } else if (value > f.value) {
                    if (f.right != null) {
                        f = f.right;
                    } else {
                        break;
                    }
                } else {
                    return f;
                }
            }
            return null;
        }
    }

    public void addNode(int value) {
        if (findNode(value) != null) {
            return;
        }

        Node n = new Node();
        n.right = n.left = null;
        n.value = value;
        Node parent = null;
        if (isEmpty()) {
            root = n;
            root.parent = parent;
        } else {
            Node p = root;
            while (p != null) {
                parent = p;
                if (n.value > p.value) {
                    p = p.right;
                } else {
                    p = p.left;
                }
            }
            if (n.value < parent.value) {
                parent.left = n;
            } else {
                parent.right = n;
            }
            n.parent = parent;
        }
    }

    public void clear() {
        if (!isEmpty()) {
            clear(root);
        }
    }

    private void clear(Node elem) {
        if (elem != null) {
            clear(elem.left);
            clear(elem.right);
            elem = null;
        }
    }

    public Tree() {
        // nothing to do
    }

    public Tree(Tree bt) {
        root = null;
        addNode(bt.root.value);
        clone(bt.root);
    }

    private void clone(Node elem) {
        if (elem.left != null) {
            addNode(elem.left.value);
        }
        if (elem.right != null) {
            addNode(elem.right.value);
        }

        if (elem.left != null) {
            clone(elem.left);
        }
        if (elem.right != null) {
            clone(elem.right);
        }
    }

    public boolean deleteNode(int value) {
        Node d = findNode(value);
        if (d == null) {
            return false;
        }

        if (d == root && getCount() == 1) {
            clear();
            return false;
        }

        Node parent = d.parent;

        // нет потомков
        if (d.left == null && d.right == null) {
            if (parent.left == d) {
                parent.left = null;
            } else {
                parent.right = null;
            }
            return true;
        }

        // есть правый потомок, но нет левого
        if (d.left == null && d.right != null) {
            if (d == root) {
                root = d.right;
                d.right.parent = null;
            } else {
                if (parent.left == d) {
                    parent.left = d.right;
                } else {
                    parent.right = d.right;
                }
                d.right.parent = parent;
            }
            return true;
        }

        // есть левый, но нет правого потомка
        if (d.left != null && d.right == null) {
            if (d == root) {
                root = d.left;
                d.left.parent = null;
            } else {
                if (parent.left == d) {
                    parent.left = d.left;
                } else {
                    parent.right = d.left;
                }
                d.left.parent = parent;
            }
            return true;
        }

        // есть оба потомка
        if (d.left != null && d.right != null) {
            Node r = d.right;
            if (r.right == null && r.left == null) {
                d.value = r.value;
                d.right = null;
            } else if (r.left != null) {
                Node p = r.left;

                while (p.left != null) {
                    p = p.left;
                }

                d.value = p.value;

                if (p.right == null) {
                    p.parent.left = null;
                } else {
                    p.parent.left = p.right;
                }
            } else {
                d.value = r.value;
                d.right = r.right;
            }
        }
        return true;
    }
}

class Program {

    public static void main(String[] args) {

        int size = 20;
        int mass[] = new int[size];

        System.out.println("Elements of array:");
        for (int i = 0; i < size; i++) {
            mass[i] = (int) (Math.random() * 200);
            System.out.print(mass[i] + ", ");
        }

        Tree bt = new Tree();

        for (int i = 0; i < size; i++) {
            bt.addNode(mass[i]);
        }

        System.out.print("\n\nElements of tree: ");
        bt.showTree();

        Tree.Node f = bt.findNode(127);
        if (f != null) {
            System.out.println("BINGO! " + f.getValue() + "\n\n");
        } else {
            System.out.println("В дереве нет значения 127...");
        }

        for (int i = 0; i < 150; i++) {
            bt.deleteNode(i);
        }
        bt.showTree();

        System.out.print("Осталось элементов: " + bt.getCount() + "\n\n");

    }
}