public static void printTree(ClassificationTree tree,int level)
    {
        if(tree!=null)
        {
            printTree((ClassificationTree) tree.getRight(),level+1);

            if(level!=0)
            {
                for (int i=0;i<6*(level-1);i++)
                    System.out.print(" ");
                System.out.print("----");
            }
            System.out.println(tree.toString());

            printTree((ClassificationTree) tree.getLeft(),level+1);
        }
    }