public void addNode(String data) {
        if (data != null) {
            if (data.hashCode() < this.data.hashCode()) {
                if (getChildNodeLeft() == null) {
                    this.childNodeLeft = new BinaryTreeNode(data);
                    this.childNodeLeft.setParentsCount(this.parentsCount + 1);
                } else
                    this.childNodeLeft.addNode(data);
            } else {
                if (getChildNodeRight() == null) {
                    this.childNodeRight = new BinaryTreeNode(data);
                    this.childNodeRight.setParentsCount(this.parentsCount + 1);
                } else
                    this.childNodeRight.addNode(data);
            }
        }
    }